The NPOESS Preparatory Project, or NPP, satellite was originally developed as a pathfinder for the NPOESS programme. Following the cancellation of NPOESS, it will instead be used operationally. It was constructed by Ball Aerospace, and is based around the BCP-2000 satellite bus. NPP is a 1,976-kilogram satellite, with a planned mission duration of five years; however the spacecraft has a design life of seven years, and could remain operational for longer.

NPOESS was intended to combine the roles currently performed by the military Defense Meteorological Support Program (DMSP), mad the civilian Earth Observing System (EOS) and Polar Orbiting Environmental Satellites (POES), and which are used for military and civilian weather observation respectively. The programme was abandoned last year as it was over budget and behind schedule.

Instead, DMSP will be replaced by the Defense Weather Satellite System (DWSS), which is expected to enter service at the end of the decade, whilst the Joint Polar Satellite System (JPSS) will replace POES. NPP is intended to bridge the gap between EOS and JPSS, and will also serve as the first JPSS satellite to be launched. A second satellite, JPSS-1, scheduled for launch in 2014. JPSS-1 will be based on the NPP spacecraft.

Five instruments aboard NPP will be used to return data about Earth’s environment and atmosphere. The Visible Infrared Imaging Radiometer Suite, VIIRS, will be used to produce visible-light and infrared imagery of the Earth’s surface, at 22 different wavelengths. The images will be used to monitor a wide range of phenomena on the Earth’s surface.

The second instrument, Clouds and the Earth’s Radiant Energy System (CERES), is identical to four existing instruments currently in orbit; two aboard Terra and two aboard Aqua. It will be used to study the Earth’s radiation budget; monitoring the amount of energy emitted and reflected by the planet.

The Cross-track Infrared Microwave Sounding Suite, CrIMSS, is comprised of two instruments; the Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS). CrIMSS will be used to profile the temperature and humidity of the atmosphere.

CrIS will operate at infrared wavelengths, whilst ATMS will operate at much shorter, microwave, wavelengths. The data returned by the two instruments will be used to help meteorologists better understand individual storms, and to provide data for weather forecasts.

The Ozone Mapping and Profiler Suite, or OPMS, is the final instrument aboard NPP. It will be used to measure ozone levels and distribution in the troposphere, and in the upper atmosphere. That data it is expected to return will allow scientists to study the ozone distribution at a higher resolution than previous instruments. Data will also be used to forecast the ultraviolet exposure of humans in particular areas, and to monitor air quality.

ELaNa III, which will be launched along with NPP, is part of NASA’s Educational Launch of Nanosatellites, or ELaNa, programme. ElaNa is intended to provide US educational institutions with the opportunity to develop and operate spacecraft. It consists of six CubeSats, which will conduct a variety of missions.

The CubeSats, loaded into three CalPoly PPODs attached to the second stage of the Delta II, will separate from the carrier rocket during a coast phase between the second stage’s two propellant depletion burns following the separation of NPP. This is the first time a Delta II has deployed CubeSats, despite the fact that the PPOD deployment mechanism was originally designed for use on the Delta II’s second stage.

E1P-U2, or Explorer-1 [PRIME] Unit 2, was originally built as a flight spare for the Explorer-1 [PRIME] (E1P) satellite, which was lost in the failure of a Taurus-XL rocket earlier this year. E1P was itself a replacement for MEROPE, which was lost in a Dnepr launch failure in 2006. The objective of the spacecraft’s mission is to refly the radiation experiment carried by America’s first satellite, Explorer 1, using modern technology.

The original experiment led to the discovery of the Van Allen belts, and E1P was intended to be launched in 2008 to mark the fiftieth anniversary of the discovery. Funded by the Montana Space Grant Consortium, the spacecraft will be operated by the University of Montana. It is a single-unit CubeSat which will be deployed from PPOD-1, and is expected to operate for four months.

Auburn University’s AubieSat-1 is also flying in PPOD-1. Like E1P-U2, it is a single-unit CubeSat. The Alabama Space Grant Consortium has provided funding for the mission, which will study the use of two different types of film to protect the spacecraft’s solar cells.

It will also investigate the propagation of radio waves within the Earth’s ionosphere.

The final spacecraft in PPOD-1, M-Cubed, will be operated by the University of Michigan. It carries an earth imagery payload, consisting of a 2 megapixel camera with a fifty degree field-of-view and a 2.8 millimetre focal length. A secondary payload, the CubeSat On-Board Processing Validation Experiment, was developed by NASA’s Jet Propulsion Laboratory, and will process the images produced by the satellite’s camera.

The University of Michigan will also operate the Radio Auroral Explorer 2 (RAX-2) satellite; a three-unit CubeSat which fully occupies PPod-3.

It will study the effects of the Earth’s magnetic field on the spacecraft’s orbit by using high-resolution narrow beam radar to study small changes in the spacecraft’s altitude, in order to map the relationship between such changes and the magnetic field lines.

PPOD-2 contains the Dynamic Ionosphere CubeSat Experiment, or DICE, which will use two satellites to observe periodic storms in the ionosphere occurring primarily over the United States. Such storms can disrupt radio signals travelling through the ionosphere, disrupting satellite communication and navigation services. The satellites are both 1.5 unit CubeSats, measuring 15x10x10 centimetres. They will be operated by Utah State University.

The next ELaNa mission is scheduled for next July, when three PPODs will be launched aboard an Atlas V 411 rocket along with NROL-36; a classified payload for the US National Reconnaissance Office, which is likely to be a pair of Naval Ocean Surveillance System satellites. Following this, the second and third SpaceX Dragon launches under the CRS programme will carry four and five PPODs respectively.

NPP was launched by a Delta II rocket, flying from Space Launch Complex 2W at the Vandenberg Air Force Base in California. The rocket, Delta 357, was the 151st Delta II to be launched, and flew in the Delta II 7920-10C configuration.

It was the last Delta II currently manifested to launch, however the type has recently been returned to NASA’s Launch Services II (NLS-II) contract, with as many as five launches possible in coming years. It remains unclear as to whether these will actually fly, however, so Delta 357 may well be the last Delta II to fly.

The Delta II is, itself, the last of the Thor-Delta series of rockets, and its first stage is the final incarnation of the Thor rocket, which began life as an intercontinental ballistic missile in the 1950s. The first Thor was launched from Launch Complex 17B at Cape Canaveral on 26 January 1957.

A valve failure led to an immediate loss of thrust, with the rocket falling back onto the launch pad and exploding. The second flight, on 20 April 1957 was not much more successful after the rocket was accidentally destroyed range safety.

The first successful Thor launch came at the fourth attempt, on 20 September 1957. Production began later that year, with the first missiles becoming operational in 1958. Project Emily, begun in 1959, saw sixty Thor missiles transferred to the Royal Air Force, and stationed in the United Kingdom.

RAF crews also conducted launches from Vandenberg Air Force Base, testing the missiles, and providing experience for their operators. The missiles returned to the United States in 1963, marking the end of Thor’s operational life as a ballistic missile.

Several Thor missiles were subsequently deployed as anti-satellite weapons, and some were used for suborbital tests, including the ASSET reentry vehicles, whilst the majority were converted to launch satellites.

Thor was already established as an orbital launch system, having made its first orbital launch attempt in 1958, when a Thor DM-18 Able I failed to place a Pioneer spacecraft into orbit.

The Thor-Agena entered service the next year, and the first successful orbital launch of a Thor occurred on 13 April 1959, when Discoverer 2 was launched by the second Thor DM-18 Agena-A.

The Thor-Ablestar, which entered service in 1960, was the first rocket to incorporate a restartable upper stage. The Ablestar upper stage was an enlarged version of the Able stage, which had been used previously on the Vanguard rocket. The Delta upper stage was also derived from Able.

The first Thor-Delta launch occurred on 13 May 1960, and failed to place the Echo 1 communications satellite into orbit. Another attempt on 12 August the same year successfully lofted a replacement, Echo 1A.

The ninth Delta launch, in April 1962, carried the first satellite to be operated by a country other than the United States or the Soviet Union, the United Kingdom’s Ariel 1. Despite being operated by the United Kingdom, Ariel 1 was constructed in the United States, and later in 1962, a Thor DM-21 Agena-B launched the first satellite to be constructed by a country other than the USA or USSR; Canada’s Alouette 1.

Through the 1960s the Thor-Delta evolved, with its payload capacity being increased by changes to its stages, and the addition of boosters. In 1967 these changes were incorporated back into the Thor-Agena, resulting in the Thorad-Agena, which featured a stretched first stage originally developed for the Delta. Each development of the Delta rocket was designed using a sequential letter of the alphabet, and by the end of 1969, the Delta-N was in service.

The next upgrade, introduced in 1972, brought with it a new designation system. Each variant was identified by a four digit number; the first digit identifying the type of first stage and boosters, the second digit identifying the number of boosters, the third digit identifying the second stage, and the fourth digit identifying the third stage.

The 2000-series Delta, which entered service in 1974, was the first to introduce an RS-27 engine in place of the MB-3 which the Thor was originally equipped with.

In 1975, the N-I made its first flight from the Osaki Launch Complex at the Tanegashima Space Center in Japan. It consisted of a Thor first stage which was built under license, with a Japanese second stage. The N-II, which first flew in 1981, was a fully-license-produced Thor-Delta. The third variant built by Japan, the H-I, consisted like the N-I of a Thor first stage, and a Japanese second stage. It was developed into the all-Japanese H-II, which in turn was developed into to the current H-IIA and H-IIB.

In 1982, the Delta 3920 made its first flight, introducing the Delta-K upper stage, which is still in service on the Delta II. By this stage, however, the Space Shuttle was flying, and the Delta programme was coming to an end, as expendable launch systems were believed to be obsolete.

Following the Challenger accident in 1986, payloads began to transfer back to expendable rockets, with the US Air Force transferring its GPS satellites to Delta. This resulted in the development of the Delta II, which first flew on 14 February 1989.

The initial Delta II launches were of the interim 6000-series configuration, with an Extra-Extended Long Tank Thor first stage powered by a single RS-27 engine, and augmented by nine Castor-4A solid rocket motors. When the 7000 series flew in November 1990, it replaced the RS-27 with an uprated RS-27A engine, and replaced the Castors with GEM-40 motors. Seventeen 6000-series rockets were launched before the type was phased out.

The launch of NPP is the 128th launch of the 7000-series.

In addition, six 7000H-series rockets, with GEM-46 solids have also been launched, with the “Heavy” making its final flight last month carrying the GRAIL spacecraft bound for the moon.

During its 22 years in service, the Delta II has only experienced two launch failures, and it is statistically the most reliable rocket in service. The first of the two failures occurred in August 1995, when the Koreasat 1 spacecraft was left in a significantly lower orbit than planned after a solid rocket motor failed to separate from the rocket.

Despite the shortfall, Koreasat 1 was eventually able to reach its operational orbit, but not without expending a significant amount of its propellant, thereby shortening its operational life.

In January 1997, Delta 241 lifted off from Cape Canaveral carrying GPS IIR-1, the first in a new series of GPS satellites. Thirteen seconds later it exploded, showering 220 tonnes of flaming debris over the launch complex. An investigation discovered that the rocket’s onboard computer had issued a self-destruct command after detecting the structural failure of one of the solid rocket motors.

The first stage of the Delta II 7920-10C configuration which was used to launch NPP was an Extra-Extended Long Tank Thor with an RS-27A main engine and two LR-107 verniers, which ignited about two second ahead of the scheduled time of liftoff, T-0. A fraction of a second before T-0, six of the nine GEM-40 solid rocket motors igniteg, and at T-0 Delta 357 began its ascent towards orbit, flying on an azimuth of 196 degrees.

About sixty four seconds after launch, the six ground-lit solid rocket motors burnt out, and a second or two later the three air-lit motors ignited. The spent ground-lit motors remained attached to the first stage for about 22 seconds after burnout, in order to clear offshore oil rigs before they are jettisoned.

Separation of the solid rocket motors was around 86 seconds after liftoff, with the motors falling away in two groups of three. The air lit motors also burned for about 64 seconds, subsequently separating two minutes and 10.5 seconds after liftoff.

The first stage completed its burn 263.4 seconds after liftoff, with the main engine shutting down followed shortly afterwards by the two verniers. About eight seconds after main engine cutoff, or MECO, the first stage separated, and thirteen and a half seconds after MECO the second stage ignited to begin the first of four burns. The second stage was a Delta-K, powered by an AJ-10-118K engine.

The first burn lasted five minutes, 46.8 seconds, and just over four seconds into the burn, the payload fairing separated from around the satellites.

Following the end of the first burn, Delta 357 coasted for 41 minutes and 41.3 seconds before the second burn commenced. This burn lasted just 21.7 seconds, circularising the orbit for the deployment of NPP.

Spacecraft separation was seen 378 seconds after the burn ended; fifty eight minutes and forty five seconds after liftoff. The target orbit is a semi-major axis of 7201.15 kilometres, eccentricity of 0.00125, inclination of 97.703 degrees, and an argument of perigee of 69.21 degrees.

A separation burn was then made 33 minutes and 45 seconds later, putting distance between the upper stage and NPP ahead of CubeSat deployment. The separation burn lasted 39.2 seconds. Five minutes and 8.8 seconds after this burn completes, the first PPOD opened, releasing E1P-U2, AubieSat-1 and M-Cubed. The second PPOD was opened 98 seconds later, releasing the two DICE satellites, followed by the final PPOD 102 seconds after that, releasing RAX-2.

With all of its payloads deployed, Delta 357 made one more burn to deplete its remaining propellant. This lasted 31.9 seconds, and began around 13 minutes and 21 seconds after RAX-2 separates.

Delta 357 launched from Space Launch Complex 2W at Vandenberg Air Force Base, a pad constructed as Launch Complex 75-1-2 during the 1950s.

Originally used by the 75th Strategic Missile Squadron of the United States Air Force, and the Royal Air Force, for test-launching Thor missiles and training their crews, the first launch from the pad occurred on 17 September 1959.

The first orbital launch from the pad was made by a Thor-Agena in 1962, carrying a KH-4 satellite. The complex supported its first Delta launch in 1969 and its first Delta II launch in 1995.

The launch of NPP was conducted by United Launch Alliance, who operated the Delta II, Delta IV and Atlas V rockets, and provide launch services for the US government.

The next launch to be conducted by ULA will be that of the Mars Science Laboratory, which is currently scheduled for late November aboard an Atlas. The next Delta launch will be of a Delta IV in January, carrying a Wideband Global Satcom communications satellite.

(Images: NSF Member Jimvela, NASA, ULA, L2 Hisorical, Unis of Michigan and Auburn, Rocketdyne) (NSF and L2 are providing full transition level coverage, available no where else on the internet, from Orion and SLS to ISS and COTS/CRS/CCDEV, to European and Russian vehicles.)

(Click here: http://www.nasaspaceflight.com/l2/ - to view how you can access L2)

Related posts:

1. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
2. ULA Delta II launches on third attempt with NASA’s NOAA-N Prime A United Launch Alliance Delta II rocket has launched with...
3. ULA successfully launch STSS-Demo via Delta II The United Launch Alliance (ULA) launch of a Delta II...

NPP Mission:

NPP – the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project – is the first of a new generation of satellites, carrying the first of the new sensors developed for this satellite fleet, now known as the Joint Polar Satellite System (JPSS) to be launched in 2016.

The mission will provide a bridge between NASA’s Earth Observing System (EOS) satellites and the forthcoming series of JPSS satellites, as NPP will test key technologies and instruments for the JPSS missions.

“NPP’s observations of a wide range of interconnected Earth properties and processes will give us the big picture of how our planet changes,” said Jim Gleason, NPP project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.

“That will help us improve our computer models that predict future environmental conditions. Better predictions will let us make better decisions, whether it is as simple as taking an umbrella to work today or as complex as responding to a changing climate.”

The NPP spacecraft is a member of the Ball Configurable Platform (BCP) family of spacecraft designed for cost-effective, remote sensing applications. Its proven design accommodates a wide range of payloads, including optical applications with sub-meter resolutions and synthetic aperture radar.

The spacecraft bus is the eighth of 11 spacecraft built by Ball Aerospace on the same BCP 2000 core architecture. The BCP 2000 was designed to accommodate a wide variety of Earth-observing payloads that require precision pointing control, flexible high-data throughput and downlinks, and controlled re-entry.

The NPP spacecraft incorporates both MIL-STD-1553 and IEEE 1394 (FireWire) data networks to support the payload suite. The spacecraft has a 7-year design life, with a five-year mission life.

The five instruments manifested for flight on the NPP spacecraft trace their heritage to instruments on NASA’s Terra, Aqua and Aura missions, on NOAA’s Polar Operational Environmental Satellite (POES) spacecraft, and on DOD’s Defense Meteorological Satellite Program (DMSP).

Delta II Preparations:

The integration flow at VAFB has proceeded without any major issues, with only slight interruption, such as the 24 hour delay to the NPP transport and mate to the Delta II due to unacceptable winds in the Californian launch site. This process was completed on October 13.

“The SC and can were under the hook by 05:30, (prior to) waiting for ground winds to subside. The can was hoisted at 09:45, and mate was complete by 11:45. There was a ~25 minute interruption in activity due to a pad temperature sensor triggering a false alarm which forced personnel to evacuate the pad,” added L2 notes for October 13′s flow.

Engineers then worked on connecting the GN2 purge to the spacecraft, along with setting up access platforms. Once complete, the spacecraft was then put on air conditioning, while the team worked on the umbilical connections, performed basic tests and “configure for launch” testing – along with charging of the flight battery.

“Ordnance installation and connections, including stage sep ordnance electrical connections, GEM ordnance electrical connections, and SC sep ordnance electrical connections are complete,” added the flow notes.

Technicians then performed a walkdown of the vehicle, ahead of closeouts on the spacecraft, which included the installation of the Payload Fairing (PLF) by ULA engineers.

It was during this point of the flow when a “material review” resulted in a one day slip to the launch date.

“The postponement for at least 24 hours will allow time to complete the necessary engineering review before the payload fairing is installed around the spacecraft,” noted NASA in an update.

With the review passed to the satisfaction of the mission’s stakeholders, Friday’s FRR passed the launch vehicle and spacecraft for launch next Friday.

“The timing of the NPP launch could hardly be more appropriate,” noted Louis W. Uccellini, director of NOAA’s National Centers for Environmental Prediction in Camp Springs, Md. “With the many billion dollar weather disasters in 2011, NPP data is critical for accurate weather forecasts into the future.”

Upcoming milestones include the Launch Management Coordination Meeting and Mission Dress Rehearsal – set to take place over the weekend. This will be followed by Second Stage Oxidizer Load and Second Stage Fuel Load early on the launch vehicle – flying in the 7920-10 configuration – next week.

(Images: NASA) (As the shuttle fleet retire, NSF and L2 are providing full transition level coverage, available no where else on the internet, from Orion and SLS to ISS and COTS/CRS/CCDEV, to European and Russian vehicles.)

(Click here: http://www.nasaspaceflight.com/l2/ - to view how you can access L2)

Related posts:

1. ULA successfully launch STSS-Demo via Delta II The United Launch Alliance (ULA) launch of a Delta II...
2. Delta II launches with Kepler Planet-Finder Launch The Delta II launch team at the Cape Canaveral Air...
3. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...

GRAIL, or Gravity Recovery And Interior Laboratory, is a two-spacecraft mission being flown as part of NASA’s Discovery programme. It is expected to yield a better understanding of the Moon’s internal structure and thermal evolution. This will allow scientists to formulate a model of the Moon’s formation which can also be applied to terrestrial planets.

The principal scientific objectives of the GRAIL mission are to produce a map of the Moon’s lithosphere, to allow scientists to understand the Moon’s thermal evolution, and the evolution of breccia within the Moon’s crust, and to determine more details of the Moon’s interior, particularly the size of the Moon’s core, and the structure beneath impact basins.

The two spacecraft are identical, apart from the positioning of star trackers and instruments to allow the spacecraft to fly with their antennae pointing towards each other. They were built by Lockheed Martin, based around a bus developed for the USA-165, or XSS-11, satellite; a technology demonstration spacecraft operated by NASA and the United States Air Force, which was launched in 2005. Each GRAIL spacecraft has a mass of 307 kilograms, including 106 kilograms of hydrazine fuel.

The spacecraft are each equipped with two 1.9 square metre, 520-cell, solar arrays, which will generate at least 700 watts of power. The solar arrays will charge a 30 amp-hour lithium ion battery in each spacecraft, which will be used to store power for when the spacecraft are not in sunlight. Propulsion of each spacecraft will be provided by an MR-106L monopropellant engine, capable of generating 22 newtons of thrust.

The spacecraft are three-axis stabilised, with reaction wheels and eight warm gas thrusters, each capable of producing 0.9 newtons of thrust, being used aboard each spacecraft for attitude control. Sun and star trackers and inertial measurement units will allow the spacecraft to determine their orientation. The spacecraft carry avionics systems which are derived from those developed for the Mars Reconnaissance Orbiter, which was launched in 2005.

Each spacecraft carries two transponders operating in the IEEE S band (NATO E band), which will be used to relay data to the ground and to upload commands to the spacecraft. A further S band transponder, the Time-Transfer Assembly, will be used to transmit signals between the spacecraft to synchronise their onboard chronometers.

Two IEEE X band (NATO I or J band) transponders, the Radio Science Beacon, will be used to transmit signals to Earth for Doppler ranging. Finally an IEEE Ka band (NATO K band) transponder, the Microwave Assembly, will be used to find the distance between the two spacecraft, and track their relative motion.

The Ka band transponder forms part of the Lunar Gravity Ranging System or LGRS, which is GRAIL’s primary instrument. LGRS consists of four elements; the Ultra-Stable Oscillator, or USO, will be used to generate an oscillating signal to synchronise the instruments. This signal will then be transmitted through both the Microwave Assembly (MWA) and Time-Transfer Assembly (TTA) antennae. TTA broadcasts the signal as a ranging code, similar to those transmitted by Global Positioning Satellites. Finally, the data is collected by the Gravity Recovery Processor Assembly, or GPA, which processes it for transmission back to Earth.

LGRS is derived from the K-Band Ranging (KBR) instrument aboard the Gravity Recovery And Climate Experiment, or GRACE, spacecraft, which were launched in March 2002. GRACE, like GRAIL, consists of two spacecraft using radio signals to map the gravitational field, however it is studying Earth’s gravitational field instead of the Moon’s.

The two spacecraft also carry the Moon Knowledge Acquired by Middle school students, or MoonKAM, student outreach payload. This will be used to image areas of the Moon at the request of schoolchildren. A similar programme for Earth imagery, EarthKAM, has been operated aboard the International Space Station since 2001 and also flown on Space Shuttle missions STS-89 and STS-99. A prototype, KidSat, was also flown on STS-76, STS-81 and STS-86.

GRAIL is the eleventh mission to be launched as part of NASA’s Discovery programme, which was started in 1992. Discovery is a medium-class programme intended to study the Solar system. many of NASA’s recent planetary missions have been conducted as part of it. The first Discovery mission, NEAR, was launched in February 1996 to explore the Asteroid 433 Eros.

The next mission, Mars Pathfinder was launched in December 1996, placing a lander on Mars, and deploying the Sojourner rover. The third mission, Lunar Prospector, was launched in 1998 to study the lunar surface via spectroscopy. In 1999 the Stardust spacecraft was launched to return samples from the comet 81P/Wild 2. These samples were returned in January 2006, and the spacecraft subsequently performed an extended mission with a flyby of 9P/Tempel 1 this February, before finally being deactivated on 24 March.

The Genesis spacecraft, launched in August 2001, was the fifth Discovery mission. It collected a sample of solar wind, and returned it to Earth. During its return to Earth, its parachute failed to deploy, however some of its samples were still usable. The sixth mission, CONTOUR, was less successful. Intended to perform flybys of comets 2P/Encke and 73P/Schwassmann-Wachmann 3, CONTOUR was launched in July 2002. The spacecraft was destroyed due to a malfunction of an onboard kick motor which was intended to propel it out of Earth orbit towards its first comet encounter.

MESSENGER, the seventh mission, was launched in August 2004 and entered orbit around Mercury on 18 March this year. The eighth mission, Deep Impact, fired a probe into the comet 1P/Tempel 1, in order to study its composition. Launched in 2005, its impactor hit Tempel 1 in July of the same year, with the spacecraft then being used for an extended mission to 103P/Hartley 2.

The ninth mission of the programme, Dawn, was launched in September 2007, and entered orbit around the Asteroid 4 Vesta on 16 July this year. Following a year orbiting Vesta, it will depart for the dwarf planet Ceres, which it will also orbit. The tenth mission, Kepler, is a space telescope which is being used to look for exoplanets. It was launched in 2009.

GRAIL was launched by a Delta 356, which is a Delta II Heavy flying in the 7920H-10C configuration. It was the sixth and possibly last Delta II Heavy to be launched. Overall, its launch marked the 150th Delta II mission, and potentially its penultimate flight.

The Delta II 7920H-10C configuration consists of an Extra-Extended Long Tank Thor first stage with an RS-27A engine, fuelled by RP-1 propellant and liquid oxygen oxidiser.

Early in the ascent the first stage was augmented by nine GEM-46 solid rocket motors; six of which ignited at launch, and the other three shortly before the first six burnt out.

The second stage was a Delta-K, powered by an AJ-10-118K engine. The second stage is fuelled by Aerozine-50 propellant, with dinitrogen tetroxide being used as an oxidiser. The 7920H-10C configuration does not incorporate a third stage. A three metre, or ten foot, composite payload fairing encapsulated the spacecraft.

In the mid-1980s, launches of Delta rockets were winding down, with future payloads expected to fly aboard the Space Shuttle. Following the Challenger accident in 1986 this policy was reviewed, and in January 1987 the US Air Force ordered a new series of Delta rockets, primarily to launch Global Positioning Satellites. The Delta II made its maiden flight on 4 February 1989, in the 6925 configuration.

The 6000-series Delta IIs were built as an interim whilst the more capable 7000-series was in development. It used an Extra-Extended Long Tank Thor first stage powered by an RS-27 engine, a Delta-K second stage, and nine Castor-4A solid rocket motors. The 7000 series, which first flew in November 1990, introduced an uprated RS-27A engine, and GEM-40 solids.

The 6000-series made seventeen flights; three in the 6920 configuration and 14 in the 6925 configuration. Its final flight was made on 24 July 1992, carrying the Geotail spacecraft to study Earth’s magnetosphere. Other 6000-series payloads included nine Block II GPS satellites, four commercial communications satellites, and SDI technology demonstration experiment and two astronomy satellites; EUVE and ROSAT.

The 7000 series has seen a wider variety of configurations, with the Delta II Lite programme resulting in the development of configurations with three or four solid rocket motors, and launches being made with two or three stages, and with two different types of third stage. In all, 127 have been launched; ten in the 7320 two-stage configuration with three solid rocket motors, thirteen in the 7420 configuration with four SRMs, and twenty seven in the 7920 configuration with nine SRMs.

The 7326 configuration made three flights and the 7426 made a single flight; these had three and four solid rocket motors respectively, and both had Star-37FM third stages. The 7425 configuration, with four solid rocket motors and a Star-48B third stage, made four flights. The most-launched configuration is the 7925, which features nine SRMs and a Star-48B upper stage, and has made sixty nine flights.

The Delta II Heavy has the same configuration as the 7000 series, except that it has more powerful solid rocket motors. The GEM-46 motors, which were originally developed for the Delta III, allow the rocket to carry a heavier payload into orbit.

The Delta II is statistically the most reliable rocket in service, having only failed twice. Both failures were of 7925 configuration rockets, and both were caused by problems with the solid rocket motors.

In August 1995, during the launch of Koreasat 1, one of the nine solids failed to separate after burning out. The rocket continued to orbit, however the additional mass of the spent solid rocket motor resulted in it reaching a lower orbit than had been planned. The satellite was able to raise its own orbit, but at the expense of a significant amount of fuel.

The second failure occurred in January 1997, during the launch of the first Block IIR Global Positioning Satellite, GPS IIF-1. Thirteen seconds into the flight, the rocket self-destructed following the structural failure of one of the number 2 solid rocket motor. Over 220 tonnes of debris fell within a kilometre of the launch pad, with one piece landing in the blockhouse car park, destroying twenty vehicles.

An investigation concluded that recent changes in equipment used to transport the solid rocket motors had resulted in pressure being put onto an area of the booster, and that this had caused a crack to form around six seconds after launch. The equipment was redesigned, and additional inspections were added for future launches. The Delta II has not failed in any of the ninety four launches it has made since then.

Delta 356 could have launched GRAIL in one of two instantaneous launch windows available per day. The first of these windows opened at 8:29:45am Eastern (12:29:45 UTC), but was not taken due to unacceptable upper level winds. The second launch opportunity was, however, taken at 9:0am Eastern (13:08 UTC).

Had the vehicle launched during the first window, the rocket would have flown on an azimuth of 93 degrees. During the second window, an azimuth of 99 degrees was employed.

Processing overview article: http://www.nasaspaceflight.com/2011/09/twin-grail-satellites-ready-for-nasa-lunar-launch/

About two seconds before launch, the RS-27A main engine ignited, along with two LR-107-AN-11 vernier engines. About two tenths of a second before the scheduled liftoff time, six of the nine solid rocket motors ignited. At T-0, Delta 356 was released to begin its ascent into orbit. Twenty nine seconds into flight, the rocket was travelling at Mach 1, the speed of sound.

Around 79 seconds after liftoff, the three remaining solid rocket motors ignited. A second and a half later the six ground-lit solids were jettisoned in two groups of three, having expended their fuel. The three air-lit motors also burned for 80.5 seconds, before they too were jettisoned.

Around 263.2 seconds after launch the first stage depleted its fuel, and its main engine shut down, an event designated Main Engine Cutoff, or MECO. Shortly afterwards, Vernier Engine Cutoff, or VECO, occured, when the two vernier engines also shut down. Eight seconds after MECO the first stage was jettisoned, and five and a half seconds after that the second stage’s AJ-10 engine ignited. The payload fairing was jettisoned 4.3 seconds after second stage ignition.

Events after fairing separation tracked slightly different times, based on the 93 or 99 degree flight profile. In the 93 degree flight profile, the first burn of the second stage was to last 153 seconds. With the 99 degree profile used, it was seven tenths of a second longer.

The first burn was followed by a long coast phase, lasting 58 minutes and 40.6 seconds for the 99 degree profile. After coasting, the second stage ignited for its second and final burn, lasting 271.7 seconds on the 99 degree profile.

Nine and a half minutes after the second burn was complete, separation of the first spacecraft, GRAIL-A, occured. The upper stage was then manoeuvred, before the separation of GRAIL-B, which occured eight and a quarter minutes after that of GRAIL-A. A RocketCam mounted on the second stage was used to verify that separation had taken place.

Shortly after launch, the GRAIL spacecraft will deploy their solar arrays as they pass into sunlight for the first time since separating from their carrier rocket. GRAIL will travel to the Moon on a low-energy trajectory, via the Sun-Earth Lagrange 1 point.

The spacecraft are expected to enter selenocentric, or lunar, orbit between 31 December and 1 January. The spacecraft will subsequently manoeuvre into lower orbits, before they are moved into formation to begin collecting scientific data. At the start of the scientific phase of the mission, the spacecraft will be in circular orbits at an altitude of 55 kilometres.

Scientific operations are expected to commence on 8 March next year, and last for 82 days. Decommissioning of the spacecraft will begin on 29 May, and the spacecraft are expected to impact the lunar surface in June.

Delta 356 was the last rocket planned to depart from Cape Canaveral’s Space Launch Complex 17. It launched from SLC-17B, SLC-17A having been closed in 2009. Launch Complex 17, as it was then designated, was built between August and December 1956 to accommodate tests of the Thor missile.

The first Thor launch occurred from LC-17B on 26 January 1957, however it ended in failure when the rocket lost thrust and exploded on the launch pad. A second launch in April was erroneously destroyed by range safety after a faulty console caused the RSO to believe the rocket was flying in the wrong direction. The first successful launch occurred on 20 September, also from LC-17B.

Missile tests were made from LC-17B until 1957, after which it began to be used for orbital launches. The first orbital launch to be made from the pad occurred on 13 April 1960, when a Thor-Ablestar launched Transit 1B. The last of ten Thor-Ablestar launches from the pad occurred in May 1962, after which Delta launches from LC-17B began.

The first Delta launch from LC-17B was of Delta 11, carrying Telstar 1, the first commercial communications satellite. The pad was subsequently used by Delta A, B, C, E1, G and C1 rockets between 1962 and 1969. Between 1963 and 1965, six suborbital flights were also launched from LC-17B, carrying ASSET reentry vehicles to demonstrate technology for the X-20 DynaSoar spacecraft.

Three of these launches used the single-stage Thor DSV-2F, and the other three used the two-stage Thor DSV-2G, which included a Delta upper stage, however its launches are not officially listed as Delta launches. None of the six ASSET flights reached space; instead they flew shallower atmospheric flight profiles.

Delta launches from LC-17B resumed in September 1972, when the Delta 1000-series started using LC-17B. The 2000-series began to launch from the pad in 1974, with the last Delta 2000 launch from the complex occurring in 1979. From 1983 to 1989 it was used for Delta 3000-series launches and the short-lived interim Delta 4000 series made both of its launches from LC-17B; the first on 27 August 1989 and the second on 12 June 1990.

Delta II launches from LC-17B began on 11 December 1989. On 8 January 1991 the first Delta II 7000-series launch from LC-17B orbited a NATO communications satellite. In the mid 1990s LC-17B received modifications to accommodate the Delta III rocket, and in 1997 it was redesignated Space Launch Complex 17.

The first Delta III launch occurred on 27 August 1998, carrying the Galaxy 10 satellite. The mission ended in failure after the vehicle’s solid rocket motors ran out of hydraulic fluid, resulting in a loss of control and the destruction of the rocket by range safety.

The second Delta III launch in May 1999 also failed, after the second stage engine’s combustion chamber ruptured, leaving the Orion 3 communications satellite in a useless low Earth orbit. A third launch with a mock-up satellite also underperformed, reaching a lower than planned orbit. After these failures the Delta III was retired.

Because of its modifications to accommodate the Delta III, SLC-17B is the only launch pad which can accommodate the Delta II Heavy. The first launch of the Delta II Heavy occurred on June 10, 2003, carrying the Spirit spacecraft bound for Mars. Launches of standard 7000 series Delta IIs continued throughout the time that the Delta III and Delta II Heavy have used the pad, with the most recent launch from the complex having been made in September 2009 carrying the two STSS-Demo satellites for the US military.

In total GRAIL is the 164th launch to have been made from SLC-17B. Payloads launched from the pad in the past include Telstar 1, Syncom 1, Pioneers 8 and 9, Wind, NEAR, Mars Pathfinder, Mars Polar Lander, WMAP, the Opportunity rover, Spitzer, MESSENGER, Deep Impact, STEREO, THEMIS, Dawn, Fermi and Kepler.

The other pad in Space Launch Complex 17, SLC-17A, was used for 161 launches, beginning with a Thor test flight on 30 August 1957. The pad was used by Thor DM-18, Thor-Able, Thor-Delta, Thor DSV-2D rockets, followed by the Delta A, B, C, D, E, E1, G, L, M, M6, N, 2000 and 3000 series. From 1989 Delta II launches were made from the pad, using both the 6000 and 7000 series configurations. The final launch from the pad was of the last GPS IIR satellite, in August 2009.

The launch of GRAIL was the second of three planned Delta II launches this year. The next launch is the last currently on the manifest; however components to produce five more rockets do exist.

These components are for the Delta II Heavy configuration, however United Launch Alliance has stated that they can be converted to regular 7000-series rockets, which would be able to launch from Vandenberg Air Force Base without modifications to the launch pad. NASA is currently considering restoring the Delta II to its list of available launch systems after repeated failures of the Taurus-XL rocket.

The remaining Delta II launch is also United Launch Alliance’s next scheduled mission. It will carry the NPP weather satellite for NASA and NOAA, and is scheduled to launch from Vandenberg Air Force Base at the end of next month. Excess capacity on the rocket will be used to launch several small satellites.

(Images: ULA, NASA, L2 Historical (several gbs of hi res “Old School” Launch Vehicle photos – such as AFMTC and AMR era)

(As the shuttle fleet retire, NSF and L2 are providing full transition level coverage, available no where else on the internet. Click here: http://www.nasaspaceflight.com/l2/ - to view how you can support NASASpaceflight.com)

Related posts:

1. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
2. Delta II finally launches with COSMO-4 The United Launch Alliance (ULA) Delta II launch vehicle has...
3. ULA Delta II launches with COSMO-3 A United Launch Alliance (ULA) Delta II launch vehicle has...

Processing for launch – the final two weeks:

The final two weeks of the GRAIL (Gravity Recovery and Interior Laboratory) satellites’ processing for launch proceeded without major issue as the final Flight Readiness Reviews for the satellites and the Delta II launch vehicle paved the way for launch on Thursday, September 8 at 08:37.06 EDT or 09:16.12 EDT.

Over the last two weeks, the pad processing teams at Pad-B of Space Launch Complex 17 (SLC-17) at the Cape Canaveral Air Force Station, FL, dodged the weather to get the veteran Delta II rocket processed for its historic final launch from Florida – processing that included protecting against the possible effects of Hurricane Irene as the storm system passed off the Florida coast.

According to a GRAIL processing status report dated August 22, “Due to the close approach of Hurricane Irene and the need to protect the S/C from the elements, the team has accelerated a portion of the LV processing schedule.”

Accelerating certain parts of the GRAIL pad processing schedule allowed work teams to complete ordnance installations on the GRAIL spacecrafts’ separation systems from the Delta II rocket and payload fairing installation around the GRAIL spacecraft before Hurricane Irene was predicted to begin impacting the weather at the Cape.

Ordnance installations and electrical connections to the GRAIL-A and GRAIL-B spacecrafts were completed by mid-day August 23, per status reports available on L2.

The acceleration of the installation of the payload fairing represented a two-day acceleration to the pad processing flow. The beginning of payload fairing installation occurred on Tuesday, August 23; it was originally scheduled to begin on Thursday, August 25.

As payload fairing installation operations commenced, NASA and United Launch Alliance (ULA) reached a decision to replace the Delta II rocket’s first stage Main Engine Yaw Actuator.

The actuator had been returning “out-of-family” readings since early August, and the decision was made to replace the actuator to preclude it from interfering with a successful launch.

The replacement actuator arrived at the Cape on Wednesday, the same day payload fairing installation was completed.

With the replacement actuator at the Cape, plans were immediately created to replace the component before the potential work-stoppage due to the approach of Hurricane Irene.

In the end, Hurricane Irene ultimately posed no threat to the Cape and work proceeded on schedule while the storm passed 180 nautical miles off shore.

The Delta II rocket’s Main Engine Yaw Actuator was replaced on Thursday, August 25. Thursday’s acceptable weather also allowed the teams to proceed with First Stage Hydraulic System preparations for pre-flight testing – which occurred on Saturday, Aug. 27.

In addition to the hydraulic system testing on Aug. 27, the pad teams also commenced with testing on the replaced Main Engine Yaw Actuator.

Additional Ordnance installations took place on Monday, August 29, as did continued hydraulic system checks which were delayed from the weekend due to lightning warnings at the launch pad.

Also on Monday, August 20th, a suspect solenoid valve leak was detected and a replacement valve ordered “in the event removal and replacement is required.”

But the biggest event on Monday, Aug. 29 was the ULA systems review, a standard pre-launch countdown review to identify any constraints remaining against the rocket and its launch systems. The review identified two constraints to second stage propellant loading, both of which were expected to be closed by the August 31 Launch Vehicle Flight Readiness Review by NASA.

Final Solid Rocket Motor walksdown were completed on Tuesday, August 30 with no issues noted with the boosters. Tuesday also saw the installation of the Main Engine blanket at the base of the Delta II.

Moreover, additional testing on the suspect solenoid valve led to the decision to R&R (remove and replace) the valve.

R&R of the solenoid valve took place on Wednesday, August 31, resulting in nominal readings from the replacement valve after the R&R was complete.

Propellant loading preparations were also completed on Wednesday.

Launch countdown health checks on the GRAIL satellites were completed on Wednesday with positive results, as were spacecraft functional tests.

However, the biggest event on Wednesday was the tremendous success of the team in addressing and closing the open items that were listed as constraints to second stage propellant loading.

By Thursday, September 1, the Launch Management Coordination Meeting had been held and a Mission Dress Rehearsal was completed.

According to an official GRAIL mission processing report from Thursday, September 1, “During the launch countdown simulation, the team exercised lines of communication, readiness polling, and anomaly resolution processes.  The GRAIL team effectively demonstrated readiness for launch on September 8.”

The launch processing system database was also “fully evaluated” and the GRAIL management team approved second stage propellant loading for Friday morning.

By Friday, September 2, the Delta II rocket’s second stage was fueled, and the spacecraft processing team was prepared to stand down for the United States Labor Day holiday weekend and resume launch preparations on Tuesday, September 6.

(Images: John Mitchell and ULA)

(As the shuttle fleet retire, NSF and L2 are providing full transition level coverage, available no where else on the internet. Click here: http://www.nasaspaceflight.com/l2/ - to view how you can support NASASpaceflight.com)

Related posts:

1. ULA successfully launch STSS-Demo via Delta II The United Launch Alliance (ULA) launch of a Delta II...
2. Delta II launches with Kepler Planet-Finder Launch The Delta II launch team at the Cape Canaveral Air...
3. Last GPS IIR satellite launched on final SLC-17A Delta II A United Launch Alliance (ULA) Delta II has become the...

Delta II Launch Overview:

SAC-D, or “Satelite de Aplicaciones Cientificas D”, is the fourth in a series of Argentine scientific satellites, the first of which, SAC-B, was launched in November 1996. SAC-B was intended to study solar flares, x-rays and gamma ray bursts.

Launched aboard a Pegasus-XL rocket along with NASA’s HETE-1 satellite, both spacecraft were lost after the rocket failed to deploy them upon reaching orbit. Despite operating for ten hours before running out of power, SAC-B was unable to conduct any scientific research, and reentered the atmosphere still attached to HETE-1 and the Pegasus upper stage on 7 April 2002.

The next satellite, SAC-A, was deployed from Space Shuttle Endeavour on 14 December 1998 during the STS-88 mission; the first Space Shuttle mission to the International Space Station. It carried five experiments, primarily intended to demonstrate technology for future missions.

The primary experiment was to demonstrate the use of GPS satellites to track it in orbit. It also carried a CCD camera for Earth imaging, a magnetometer to study the magnetic field of the Earth, some experimental solar cells, and an instrument designed to track whales. The satellite remained in orbit until 25 October 1999.

The third satellite, SAC-C, was launched on 21 November 2000, atop a Delta II flying from the same launch pad and in the same configuration as will be used for the launch of SAC-D. It was a secondary payload on the rocket which launched NASA’s Earth Observing 1 (EO-1) spacecraft.

SAC-C’s primary mission was to conduct multispectral imaging over Argentina, augmented by medium and high-resolution cameras. It also carried experiments to study the effects of the Sun upon the Earth’s magnetic field, a helium magnetometer, another payload to track whales, as well as several technology demonstration payloads. The satellite is currently still in orbit.

SAC-D carries nine instruments. Its primary experiment is Aquarius, which will be operated by NASA. Aquarius is designed to study the salinity of the Earth’s oceans by means of three radiometers and a radar scatterometer. It has a mass of 320 kilograms, and is designed to operate for three years.

Five CONAE experiments are aboard the spacecraft. The Microwave Radiometer, MWR, will provide measurements of the wind, precipitation and sea ice conditions, and the amount of water vapour in the air; data which will be used to supplement that collected by Aquarius.

The New Infrared Scanner Technology experiment, or NIRST, is an instrument which will measure temperatures on the surface of the Earth. It will be operated jointly by CONAE and the Canadian Space Agency, and will primarily be used to detect fires, and to record sea temperatures in support of Aquarius.

The High Sensitivity Camera (HSC) will be used to image aurorae, fires, and the light emitted from cities. A Data Collection System (DCS) payload aboard the satellite will be used to collect and relay data from ground-based weather stations. The fifth CONAE experiment is the Technology Demonstration Package will be used to demonstrate whether a GPS receiver can be used to determine the location, velocity and rotation rate of the spacecraft.

The Radio Occultation Sounder for Atmosphere (ROSA) instrument will be operated by the Italian space agency, ASI. It will use GPS occultation measure the pressure, temperature and humidity of the atmosphere. Finally, SAC-D carries two instruments for the French Space Agency, CNES. These are ICARE-NG and SODAD, collectively known as CARMEN 1.

ICARE-NG is a 2.38 kilogram instrument which will be used to study electron and proton flux in space, and their effects upon instruments. Another ICARE-NG payload was launched as CARMEN 2, aboard the Jason-2 satellite in June 2008. SODAD consists of three detectors which will be used to study orbital debris and micrometeorites. A fourth detector, MEDET, was launched aboard Space Shuttle Atlantis during the STS-122 mission in 2008, and was subsequently installed aboard the International Space Station.

The Delta II which was used for Friday’s launch was a Delta 354, which was the 149th flight of the Delta II. The rocket flew in the 7320-10C configuration, using three GEM-40 solid rocket motors to augment the first stage - an Extra-Extended Long Tank Thor.

The second stage used was a Delta-K, while the rocket had no third stage. SAC-D was encapsulated in a composite payload fairing with a diameter of three metres (10 feet), which protected it from atmospheric pressures acting upon the rocket during ascent.

The first stage was fuelled by RP-1 propellant and liquid oxygen oxidiser, which powered a single RS-27A main engine, and two LR-101-AN-11 vernier engines used to control the rocket’s attitude. The Delta-K was powered by an AJ-10-118K engine, which burns Aerozine-50 propellant and dinitrogen tetroxide oxidiser. The AJ-10-118K is a derivative of the engine used on the second stage of the Vanguard rocket, which was used for the United States’ first attempt to orbit a satellite in 1957.

Three hours minutes before launch, the terminal countdown began, and an evacuation klaxon was sounded. Over the next fifty minutes, the Missile Hazard Area was cleared. About two minutes into the countdown, activation of the Redundant Inertial Flight Control Assembly (RIFCA) began, a process lasting a little over seventy minutes. Shortly after this started, pressurisation of helium and nitrogen tanks aboard both stages began.

Pressurisation of the first stage tanks took around fifteen minutes, whilst pressurisation of the second stage tanks lasted for a little under seventy minutes.

Twenty minutes into the countdown, and 160 minutes before launch, the countdown reached T-130 minutes and fuelling of the first stage began. In the event of high winds at the launch site, this is sometimes conducted before the start of the terminal countdown, in order to increase the mass and lower the centre of gravity of the rocket before the retraction of the Mobile Service Tower (MST), in order to make the rocket more stable. Either way, fuelling lasts thirty five minutes, as was the case for Friday’s preparations.

Between 130 and 105 minutes before launch, testing of the rocket’s C-band beacon was conducted. About 105 minutes before launch the air conditioning system was set to high heat mode, and at around the same time loading of liquid oxygen into the first stage tank began. Liquid Oxygen loading took  just under 40 minutes, concluding around 67 minutes before launch.

Also around 67 minutes before launch the command carrier is activated, and for the next ten minutes, tests were performed upon the command receivers. Then the first stage hydraulics system was activated, and slew checks were performed on the engines for ten minutes. Five minutes of radio frequency link checks followed.

Forty five minutes before launch, the countdown entered a planned twenty minute hold at T-15 minutes. At the end of this hold the helium and nitrogen tanks were topped off. Twenty minutes before launch the fuel tank was pressurised, following which status checks were conducted.

Fourteen minutes before launch the countdown enters a ten minute hold, final checks were conducted. Once the hold ends, the rocket and spacecraft were transferred to internal power, armed, and a final go was given from spacecraft controllers.

Two seconds before launch, the first stage engines ignited. At T-0 seconds, the solid rocket motors also ignited, and Delta 354 began to climb away from its launch pad towards orbit, along an azimuth of 169 degrees.

The rocket passed through the sound barrier 36.1 seconds after launch, and shortly afterwards it experienced the area of maximum dynamic pressure, Max-Q. Sixty four seconds into the flight the solid rocket motors burnt out, however they remained attached for another thirty five seconds to avoid the possibility that they could hit oil rigs off the coast of California.

Four minutes and 24.2 seconds after lifting off, Main Engine Cutoff, or MECO, occurred, followed shortly afterwards by Vernier Engine Cutoff, or VECO. These events marked the end of the first stage burn, the stage having expended all of its fuel. First stage separation from the second stage occurred eight seconds after MECO, with the second stage engine igniting five and a half seconds after staging.

The first burn of the second stage lasted 398.4 seconds, concluding 11 minutes and 16.1 seconds after launch. About 12.3 seconds after the start of the burn, the payload fairing separated from the rocket, with the exact time of separation being determined by sensors monitoring whether the rate of free molecular heating has dropped below 1,135 watts per square metre (0.1 British thermal units per square foot per second).

Following the completion of the first burn, Delta 354 entered a coast phase lasting 41 minutes and 3.6 seconds, before the AJ-10 engine ignited again for its second burn. This burn lasted only 12.3 seconds, in order to circularise Delta 354′s orbit. Four minutes and ten seconds after the conclusion of the burn, and 56 minutes and 42 seconds after lifting off, the SAC-D satellite separated from the upper stage of Delta 354.

At spacecraft separation, SAC-D’s orbit is expected to have a semi-major axis of 7038.099 kilometres with eccentricity of 0.0012, giving it an apogee of 679.1 km (422 miles) and a perigee of 662.2 km (411.5 miles). The orbit will have an inclination of 98.08 degrees to the equator.

After spacecraft separation, the second stage usually performs a helium blowdown manoeuvre to move away from the satellite, followed by two further burns; one to lower the upper stage’s orbital perigee, and one to deplete any remaining fuel. Whilst they are likely to occur, United Launch Alliance has not confirmed whether these manoeuvres will be performed during the flight of Delta 354.

Delta 354 launched from the West pad of Space Launch Complex 2 (SLC-2W) at Vandenberg Air Force Base. Originally built as Launch Complex 75-1-2 in the 1950s, SLC-2W and was used by the 75th Strategic Missile Squadron of the United States Air Force and the Royal Air Force, to conduct test and training launches of Thor missiles. From 1962 Thor-Agena rockets began making orbital launches from the complex, and in 1969 Delta launches from the complex started. In 1995 the Delta II made its first launch from the complex 1995.

The launch of Delta 354 marked the 31st and final flight of the Delta II Med-Lite series, developed in the late 1990s to accommodate payloads which did not require a full-capacity Delta II with nine solid rocket motors. The Med-Lite series consisted of the 7320-series and the 7420-series, with three and four solid rocket motors respectively. The 7420-series made eighteen flights, concluding with COSMO-4 last October, whilst the launch of SAC-D is the thirteenth launch of a 7320-series rocket.

The 7300-series Delta II first flew on 24 October 1998, carrying the Deep Space 1 and SEDSat spacecraft. This was one of three launches in the 7326 configuration, featuring a Star-37FM upper stage. The other two 7326 launches were those of IMAGE in March 2000, and Genesis in August 2001. The 7320 configuration, with no upper stage, has been used for all other launches, beginning with FUSE on 24 June 1999. Its most recent launch was on 14 December 2009, with the launch of WISE.

The launch of SAC-D marked the 149th flight of the Delta II, with two more launches scheduled. Components to build five Delta II Heavy rockets exist; however they have not yet been assembled or assigned to specific payloads. NASA has reportedly held talks with United Launch Alliance about restoring the Delta II to its Launch Services Contract, and it has been rumoured that NASA has been considering assigning the launch the OCO-2 satellite to a Delta II, after the Taurus-XL rocket which is currently scheduled to launch it experienced two consecutive failures.

The next scheduled Delta II launch is currently expected to occur on 8 September, when the final flight of a Delta II from Cape Canaveral will orbit NASA’s GRAIL spacecraft on a mission to the Moon. Prior to that, next month a Delta IV will launch a Global Positioning System satellite from Cape Canaveral.

(Images: ULA)

Related posts:

1. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
2. Delta II finally launches with COSMO-4 The United Launch Alliance (ULA) Delta II launch vehicle has...
3. ULA Delta II launches with COSMO-3 A United Launch Alliance (ULA) Delta II launch vehicle has...

Scrubs:

The opening launch attempt on Sunday was scrubbed due to an “engine section heater” issue, prior to a 24 scrub turnaround being called.

The second attempt, again tracking a 7:20pm PDT T-0 suffered a hold with around two minutes remaining in the countdown. Due to the one second launch window, the attempt was scrubbed. The United Launch Alliance (ULA) noted the issue was associated with the Gaseous Nitrogen purge.

“During the terminal launch countdown Monday, mission managers noted an insufficient flow of Gaseous Nitrogen in the Delta II engine compartment,” read the statement. “Gaseous Nitrogen is used to ensure that critical components in close proximity to cryogenic propulsion systems are kept warm.”

The third scrub was caused by a low voltage reading on the second stage, scrubbing the launch for 48 hours in order to allow the crews to rest ahead of the next attempt.

“During the terminal launch countdown on Tuesday, at approximately one minute before launch, mission managers noted a low second stage battery voltage reading.  This battery is used to power the electrical systems on the Delta II second stage during flight,” noted ULA.

“To allow for crew rest after three straight days of launch attempts and engineers the time required to correct this issue, the next launch attempt is scheduled for Nov. 4.”  However, this was delayed further to November 5, again at 7:20pm PDT.

Delta II Mission:

The COSMO-SkyMed programme is a partnership between ASI (the Italian Space Agency), the Italian Ministry of Defence, and e-GEOS, a commercial organisation. It consists of four satellites, of which COSMO-4 will be the last, which have all been launched by Delta II rockets over the last three and a half years.

The first satellite, COSMO-1, was launched on June 2007, and was followed by COSMO-2 and 3 in December 2007 and October 2008 respectively. The satellites produce images using 9.6 gigahertz synthetic aperture radar, and transmit them to Earth. The images are used for defence, scientific, disaster monitoring and commercial purposes.

Along with France’s Pleïades satellites, which are expected to launch next year, COSMO-Skymed forms part of the Orfeo programme, a collaboration between the French and Italian governments to share satellite reconnaissance capabilities.

COSMO-4, like its three predecessors, was constructed by Thales Alenia Space, formerly Alenia Spazio, and is based around the Prima satellite bus. This bus has also been used for the Canadian Radarsat-2 spacecraft, and will be used for four of ESA’s Sentinel spacecraft. The spacecraft has a mass of 1,900 kilograms, and is expected to operate for five years.

The flight will use Delta 350. The rocket will fly in the Delta II 7420-10C configuration, comprised of four GEM 40 solid rocket motors augmenting an Extra-Extended Long Tank Thor first stage, a Delta-K second stage, and no third stage. A three metre (10 foot) payload fairing will encapsulate the satellite, protecting it from the pressures acting on the vehicle as it climbs through the atmosphere.

Two seconds before launch, the RS-27A main engine of the first stage, along with two LR-101-NA-11 vernier engines, will ignite. The first stage engines burn RP-1 propellant, which is oxidised by liquid oxygen. When the countdown reaches zero, the solid rocket motors will ignite, and Delta 350 will begin its ascent towards orbit. Thirty and a half seconds into the flight, the rocket will reach Mach 1, the speed of sound. Just under fifteen seconds later, it will pass through Max-Q, the area of maximum dynamic pressure.

The solid rocket motors will burn out sixty four seconds after launch, and following a seventeen and a half second delay to avoid debris falling on oil rigs off the Californian coast, the motors will be jettisoned. Eighty five seconds after launch, the rocket will begin a dogleg manoeuvre to optimise its flight azimuth for achieving its target orbital inclination. The manoeuvre will last thirty five seconds.

Four minutes and twenty four seconds into the flight, the first stage fuel will be depleted, and the main engine will cut off, followed a few seconds later by the two verniers. These events are known as MECO and VECO respectively. Eight seconds after MECO, stage separation will occur, with the second stage’s AJ-10-118K engine igniting five and a half seconds later.

The second stage uses hypergolic fuels; Aerozine-50 propellant and dinitrogen tetroxide oxidiser. This will be the first of four burns made by the second stage during Delta 350′s mission, two of which will occur whilst it is still carrying the payload.

The payload fairing will separate from around the spacecraft approximately four seconds after the second stage ignites. The exact time of separation will be determined by sensors detecting that the rate of free molecular heating on the vehicle has fallen to or below 1,135 watts per square metre (0.1 British thermal units per square foot per second).

The second stage’s first burn will last six minutes, 43.6 seconds, and will leave Delta 350 in an initial orbit with an apogee of 645 kilometres, a perigee of 185 kilometres, and 97.8 degrees of inclination. During the first burn, at a mission elapsed time of seven minutes, 17.5 seconds, the Command Receiver Decoders on the vehicle will be deactivated. The Command Receiver Decoders are devices used by range safety to activate the rocket’s flight termination system in the event of a failure.

The Delta II’s flight termination system has only ever been used once, on the January 1997 launch of the first GPS IIR satellite, when the rocket’s onboard computer issued a self-destruct command after detecting the premature separation of a solid rocket motor.

The first burn of the second stage will end with cutoff, SECO-1, just over eleven minutes and twenty five seconds into the launch. The rocket will then begin a coast period lasting a little over forty two minutes. At mission elapsed time fifty three minutes twenty seven seconds, the stage will ignite for its second burn. This will last 12.4 seconds, and will end with the second cutoff, SECO-2. Delta 350 will then reorient for spacecraft separation, which is expected to occur exactly fifty eight minutes after launch.

COSMO-4 will separate from the carrier rocket into a low Earth orbit with a perigee of 631.5 kilometres, an apogee of 619.9 kilometres, 97.86 degrees of inclination to the equator, a semi-major axis of 7006.7 kilometres, with 0.00127 eccentricity. The satellite will cross the equator on an ascending node two minutes and 1.5 seconds after separating from the rocket.

After spacecraft separation, the second stage will manoeuvre away from the satellite and perform two further burns. Half a second after separation, helium blowdown will be used to manoeuvre away from the spacecraft. This manoeuvre will last forty one and a half seconds, and will provide a total delta-v of 0.5 metres per second.

One hour, sixteen minutes and forty seconds after launch, the third burn will begin, with the AJ-10 engine firing for five seconds to lower the perigee of the stage’s orbit, and to manoeuvre farther away from the payload. Nine minutes and fifty five seconds later the stage will ignite again for its final burn to dispose of propellant. This burn is expected to last 28.7 seconds, leaving the Delta-K in a 178 by 617 kilometre orbit, inclined at 98.35 degrees. It will then be left to decay from orbit naturally.

The launch marks the 350th flight of a Delta rocket. This figure includes modern rockets such as the Delta III and Delta IV, which have strayed away from the series’ traditional design, and excludes vehicles built under licence in Japan as the N-I, N-II and H-I. The first Delta launch occurred in May 1960, and failed to loft the first Echo communications satellite.

Early in the programme, the rocket was known as Thor-Delta, with the name Delta relating to the second stage. The rockets consisted of a Thor missile, the Delta second stage, and depending on mission requirements, a solid third stage.

The Delta stage was derived from the Able, originally developed for the Vanguard rocket, but enhanced by the addition of a gaseous attitude control system. The basic design was modified many times during its service life, with its LEO payload capacity increasing from less than 300 kilograms on the original Thor-Delta to over 6,000 kilograms with the Delta II 7920H.

Delta 350 will launch from Vandenberg Air Force Base’s Space Launch Complex 2W. This facility was built in the 1950s as Launch Complex 75-1-2, and was used by the 75th Strategic Missile Squadron of the United States Air Force, and the Royal Air Force, to test Thor missiles and train crews in their operation. Orbital launches from the complex began in 1962, with Thor-Agena rockets. The first Delta from SLC-2W launched in 1969. The Delta II first used the complex in 1995.

The launch is the 148th flight of the Delta II, with three more remaining to be flown. Components for five further rockets exist, however they have not yet been assigned to any specific payloads, and the rockets have not yet been assembled. The next Delta II launch is currently scheduled to occur on 9 June 2011, with the Argentine SAC-D satellite. The other two remaining launches are those of the GRAIL lunar probe, and the NPP weather satellite, both of which are also scheduled to occur next year.

This will also be the final flight of the Delta II 7400 series and the 7420 configuration. The 7400 series, along with the 7300 series, was developed as part of NASA’s “Med-Lite” requirement for a rocket to launch payloads too large for small rockets like Pegasus and Athena, but too small for the heavier Delta II 7900 series. The Delta II 7420 was the first member of the 7400 series to fly, and made its maiden flight in February 1998.

Its first seven launches each deployed four Globalstar communications satellites, and following the seventh Globalstar launch, which occurred in February 2000, the configuration was not used again for over six years. In April 2006 A Delta 7420 launched the CALIPSO and CLOUDSAT spacecraft for NASA. This launch was followed by those of the first two COSMO-SkyMed satellites in 2007, and the GeoEye-1 commercial imaging satellite and COSMO-3 in 2008. The launch will be the thirteenth flight of the configuration, and the eighteenth of the 7400 series.

The other members of the 7400 series, the 7425 and 7426, were three-stage configurations topped with Star-48B and Star-37FM upper stages respectively. The 7425 made four flights, the first of which occurred in December 1998, carrying the Mars Climate Orbiter. Subsequent launches carried the Mars Polar Lander and Deep Space 2, the Wilkinson Microwave Anisotropy Probe, and the final flight, which occurred in July 2002, carried CONTOUR.

Although all four launches were successful, WMAP is the only spacecraft launched on a Delta 7425 to have achieved any success; CONTOUR exploded around a month after launch as it attempted to depart Earth orbit, MCO flew into the atmosphere of Mars due to a unit conversion error, and MPL was lost when it attempted to land on Mars. The only launch of the 7426 configuration occurred in February 1999, and carried the Stardust spacecraft bound for the comet 81P/Wild 2.

The next Delta launch is scheduled to occur on 15 November, when a Delta IV Heavy will orbit the NRO L-32 payload for the US National Reconnaissance Office. NRO L-32 is believed to be either a Lacrosse radar imaging satellite, or a Mentor signals intelligence spacecraft, although its exact purpose is classified.

Related posts:

1. ULA Delta II launches with COSMO-3 A United Launch Alliance (ULA) Delta II launch vehicle has...
2. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
3. ULA Delta II launches on third attempt with NASA’s NOAA-N Prime A United Launch Alliance Delta II rocket has launched with...

Delta II/WISE Preview:

The Wide Field Survey Explorer, or WISE, is a 674 kilogram (1485 pound) satellite, which NASA will use to conduct infrared astronomy. Its primary mission is to conduct an all-sky survey, whilst it will additionally conduct observations related to galaxies with high luminosity, and the nearest stars to Earth. It will also be used to produce a catalogue for use by the James Webb Space Telescope, when it is launched.

WISE will serve as a replacement for the Wide-field Infrared Explorer (WIRE), which failed within hours of reaching orbit in 1999.

WISE is equipped with a 40 centimetre IR telescope, which is cooled to less than 17 Kelvin by a two-stage two stage cryostat using solid hydrogen as a coolant. Work to fill the cryostat began on 29 October, and concluded on 12 November. The hydrogen was kept solid by coils containing liquid helium, which cooled the hydrogen. The helium cooling was terminated yesterday in preparation for launch.

If the launch does not occur within two days, a delay will be necessary to re-freeze the hydrogen. It is expected that once in orbit, the hydrogen will last for around ten months. The satellite was built by Ball Aerospace, and is based on the RS-300 bus. It has an expected lifespan of seven months.

WISE is a Medium Explorer (MIDEX) satellite, forming part of the Explorer programme. If it reaches orbit it will be designated Explorer 92. The first Explorer satellite, Explorer 1, was launched on a Juno I rocket on 1 February 1958, and became the first US satellite to successfully reach orbit. To date, 89 Explorer satellites have reached orbit, with several more lost in launch failures. Initially Explorer designations were given to all satellites regardless of launch outcomes; however since 1959 the designations have only been given to satellites that reached orbit.

The target orbit for the WISE launch is one with a semi-major axis of 6,912 kilometres (3,732 nautical miles), eccentricity of 0.00133, and 97.5 degrees of inclination; a retrograde low Earth orbit with approximately 530 kilometres altitude.

Delta 347 is a Delta II rocket which uses the 7320-10C configuration. At launch, its first stage will be augmented by three GEM-40 graphite-epoxy motors – small solid boosters used to provide additional thrust during the first minute of flight.

The 7320-10C is a two-stage configuration, with an Extra-Extended Long Tank Thor (XLTT) first stage, and a Delta-K second stage. A 3 metre (10 foot) composite payload fairing will encapsulate the spacecraft.

The Delta II entered service in 1989, and is one of the most reliable rockets currently in service; having made 146 flights to date with only one failure and one partial failure. After Delta 347, another four Delta II flights are currently planned before the rocket is retired from service, however it is believed that additional rockets are available should further launch contracts be signed.

Today’s launch will be the thirty-seventh to be conducted by United Launch Alliance, which was formed in 2006 to supply orbital launch services to the United States government. If the launch occurs today, it will be on the third anniversary of ULA’s first launch, which was conducted using a Delta II 7920-10C flying from the same launch complex. That launch, designated NRO L-21, placed the USA-193 satellite into orbit; a spacecraft which malfunctioned immediately after launch and was destroyed in 2008 by a modified SM-3 missile.

The RS-27A main engine of the first stage, which burns RP-1 propellant oxidised with liquid oxygen, will ignite about two seconds before launch. At liftoff, the solid rocket motors will ignite as well, and Delta 347 will begin its ascent. It will fly downrange along an azimuth of 196 degrees from Vandenberg, passing through Mach 1, the speed of sound, 35.7 seconds into the flight. Fifty seconds after launch, it will pass Max-Q, the point at which the vehicle will experience maximum dynamic pressure.

Sixty four seconds after launch, the solid rocket motors will burn out. They will remain attached for a further thirty five seconds in order to clear oil rigs off the coast of California in the interests of range safety. One hundred seconds into the flight, a dog-leg manoeuvre to adjust the rocket’s trajectory will commence, lasting forty seconds. Just over two hundred and sixty two seconds after lifting off, the first stage will cut off, an event known as MECO.

Eight seconds after MECO, the first stage will be jettisoned, and the second stage’s AJ-10 engine will ignite after a further five and a half seconds, burning hypergolic Aerozine-50 propellant with dinitrogen tetroxide oxidiser. Two hundred and ninety seconds after launch, the payload fairing will separate from around the spacecraft. Six hundred and twenty two seconds into the flight, and following a burn lasting about five minutes and forty five seconds, the second stage will shut down having completed its first burn.

With the first burn complete, Delta 347 will begin a coast phase, during which time it will reorient itself to provide better thermal conditions. The coast will last until 51 minutes and 40 seconds into the flight, at which time restart will occur, beginning the second stage’s second burn. This burn will last eight and a half seconds, and will be followed by the upper stage manoeuvring to the correct attitude for spacecraft separation.

Fifty five minutes and twenty seconds after launch, the spacecraft will separate from Delta 347. The separation will be observed by an Ecliptic Enterprises RocketCam camera mounted on the upper stage. Following separation, Delta 347 will perform additional manoeuvres to raise its orbit, in order to mitigate debris in low Earth orbit.

Delta 347 will launch from Vandenberg Air Force Base’s Space Launch Complex 2W (SLC-2W), which was originally built for tests of Thor IRBM during the late 1950s and early 1960s. Originally designated LC-75-1-2, the first launch from the complex was conducted by the Royal Air Force in 1959, using a Thor missile. The Delta II has used the complex since 1995.

This is the seventh Delta II launch to occur this year; the last time the rocket is expected to achieve such a high flight rate. It is also the twenty-fourth and last American orbital launch attempt of the year. Only one Delta II launch is scheduled for 2010, which will be of a 7940 configuration, and will carry the Italian COSMO-4 satellite.

The next scheduled ULA launch is of an Atlas V with the Solar Dynamics Observatory, which is currently planned for 3 February. The day before, the SpaceX Falcon 9 is slated to make its maiden flight in what is currently scheduled to be the first US orbital launch attempt of the year.

Related posts:

1. ULA successfully launch STSS-Demo via Delta II The United Launch Alliance (ULA) launch of a Delta II...
2. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
3. Delta II finally launches with COSMO-4 The United Launch Alliance (ULA) Delta II launch vehicle has...

Launch Preview:

The WorldView-2 spacecraft is an optical imaging satellite, which will be operated by Colorado-based DigitalGlobe. It was constructed by Ball Aerospace, and is based on the BCP-5000 satellite bus. It has a mass of 2,800 kilograms, and an anticipated operational lifespan of seven and a quarter years.

It will be the second BCP-5000 satellite to be launched, following the earlier WorldView-1 satellite in 2007. DigitalGlobe advertise the satellite as having the “highest resolution available commercially” – via a camera with an aperture of 110 centimetres, and is capable of producing images in eight spectral bands; red, green, blue, yellow, near-infrared, “red edge”, “coastal”, and “near-infrared 2″.

WorldView-2 is the fifth satellite to be launched for DigitalGlobe, which was founded in 1993 as the WorldView Imaging Corporation. In 1995 it merged with the remote sensing division of Ball Aerospace to form EarthWatch Incorporated. Its first satellite, EarlyBird-1, was launched in December 1997, however its power system failed four days after launch and the satellite was declared a total loss.

A second satellite, QuickBird-1, was lost in a launch failure in November 2000, followed by Quickbird-2 – which was successfully launched in October 2001. In 2002 EarthWatch was renamed DigitalGlobe, and in September 2007 WorldView-1 was launched on a Delta II.

Thursday’s flight will use Delta 345, the three hundred and forty fifth Delta family rocket to be launched. It will fly in the Delta II 7920-10C configuration, which consists of an Extra-Extended Long Tank Thor first stage, augmented at liftoff by six GEM 40 solid rocket motors, with a further three GEM 40 motors igniting later in the flight.

The first stage is fuelled by RP-1, with liquid oxygen being used as an oxidiser. The second stage will be a Delta-K, which will complete the ascent, placing the satellite into orbit. It burns Aerozine-50 propellent in dinitrogen tetroxide oxidiser. A 3-metre (10-foot) diameter composite payload faring will encapsulate the spacecraft during its ascent through the atmosphere.

The first stage is powered by an RS-27A main engine, with two vernier engines for roll control, all of which will ignite around two seconds before liftoff. At liftoff, the six ground-lit GEM 40 motors will also ignite, and Delta 345 will be released to begin its climb to orbit. Just under thirty three seconds after launch, the rocket will pass through Mach 1, the speed of sound, and about forty eight seconds after launch it will be subjected to maximum dynamic pressure, or max-Q.

Sixty four seconds into the flight, the six solid motors which ignited at launch will burn out, with the three air lit motors igniting one and a half seconds later. The spent motors will remain attached for a further 20.5 seconds in order to avoid debris hitting an oil rig, before separating in two groups of three, one second apart. Ninety seconds into the flight, Delta 345 will yaw to begin a dog-leg manoeuvre in order to adjust the orbital inclination of its destination. The manoeuvre will last fifty two seconds.

Around two minutes and ten seconds into the launch, the air-lit motors will burn out, and about two seconds later they will separate. The first stage will then power Delta 345′s ascent until its fuel is depleted. This is scheduled to occur four minutes and thirty one seconds into the flight, at which time the first stage main engine will shut down, an event known as MECO. The two verniers will follow suit shortly afterwards, at an event which is known as VECO.

Eight seconds after MECO, the first and second stages will separate, with the second stage’s AJ-10-118K engine igniting five and a half seconds after staging. Four second stage burns are planned for Delta 345, with two occurring prior to spacecraft separation, and the remaining two occurring afterwards.

Around four seconds after the second stage ignites, the payload fairing will separate. This event is scheduled to occur at a point when the rate of free molecular heating on the vehicle falls below 1,135 watts per square metre, or 0.1 British thermal units per square foot per second. The first burn of the second stage will conclude with cutoff, or SECO-1, ten minutes and fifty two seconds after launch. Delta 345 and its payload will be in an orbit of 195 by 805 kilometres (106 by 435 nautical miles), inclined at 98.6 degrees.

Following SECO-1, Delta 345 will manoeuvre to its coast attitude, and a thermal conditioning, or “barbecue” roll will be initiated, with the upper stage rotating at a rate of two degrees per second. Midway through the coast phase, the direction of the roll will be reversed. Shortly before the second burn is initiated, the roll manoeuvre will be terminated, and the rocket will realign to the necessary attitude for the burn. Ignition will occur fifty three minutes and twenty four seconds into the flight.

The second burn will last twenty two seconds, ending with SECO-2. This will leave Delta 345 in a parking orbit of 764 by 776 kilometres (413 by 419 nautical miles). The burn will not affect inclination. Following SECO-2, the vehicle will reorient for spacecraft separation, and then begin a spin-up roll manoeuvre, to a rate of nine degrees per second. Sixty one minutes and forty seconds after liftoff, WorldView-2 will separate from the carrier rocket.

After the spacecraft has separated, the second stage will perform a series of evasive manoeuvres and burns. Ten minutes after separation, the rocket will perform a twenty-five second cold gas evasive manoeuvre. Just under eighteen minutes later, the second stage will make its third burn, which is scheduled to last five seconds. Eight minutes and fifteen seconds after SECO-3, the fourth burn will begin. This will be the depletion burn, and is scheduled to last around fifty two seconds.

Vandenberg Air Force Base’s Space Launch Complex 2W will be used for today’s launch. The pad, which was originally designated 75-1-2, was built for use by Thor missiles attached to the 75th Strategic Missile Squadron of the United States Air Force. The first launch from the pad occured on 17 September 1959, and was conducted by the British Royal Air Force.

In 1962, the first orbital launch from the complex occurred, when a Thor-Agena placed a KH-4 reconnaissance satellite into orbit. The first launch of a Delta from SLC-2W occurred in 1969, and in 1995 the Delta II began using the complex. It is currently designated as the launch site for all but one of the remaining Delta II launches.

Today’s launch is the 146th flight of the Delta II. The next Delta II launch is scheduled to occur on 7 December, with the WISE satellite for NASA. Before that, a Delta IV is scheduled to launch on 19 November, with the WGS-3 military communications satellite. The next launch for United Launch Alliance is currently planned to be an Atlas V with a DMSP military weather satellite, on 18 October.

Related posts:

1. Last GPS IIR satellite launched on final SLC-17A Delta II A United Launch Alliance (ULA) Delta II has become the...
2. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
3. ULA successfully launch STSS-Demo via Delta II The United Launch Alliance (ULA) launch of a Delta II...

Launch Preview:

The Space Tracking and Surveillance System, or STSS, is a programme which was originally proposed in the 1980s by the Strategic Defense Initiative Organization. Originally known as the Space Surveillance and Tracking System, it was envisioned as a system to track ballistic missiles from Low Earth orbit.

It grew into a programme named Brilliant Eyes, which later became the SBIRS-Low component of the US Air Force’s Space-Based Infrared System. In 2002 the Missile Defense Agency took over the programme, and it became known as STSS.

The STSS-Demo satellites were originally built as demonstrators for Brilliant Eyes, and later SBIRS. After a decision was made to proceed with the operational programme without conducting test launches, the two demonstration satellites were stored. In 2002, this decision was reversed, and the demonstration satellites were revived as STSS Block 2006.

The two satellites were built by Northrop Grumman, with their sensors being produced by Raytheon. They have a combined mass of 2,244 kilograms, and are attached to each other, with the lower satellite, SV-2, being attached to a component designated as an “Orbital Insertion Stage”, which will function as a Payload Attachment Fitting.

Wednesday’s launch will use the Delta II 7920-10C configuration. At launch the first stage, an Extra-Extended Long Tank Thor, will augmented by nine GEM 40 solid rocket motors. Once the first stage has completed its burn, the second stage, a Delta-K, will ignite to complete the ascent and place the satellites into orbit.

For the first few minutes of the flight, the satellites will be encapsulated in a 3-metre (10-foot) diameter composite payload faring.

Around two seconds before launch, the RS-27A main engine of the first stage will ignite, along with two smaller vernier engines which will provide roll control for the rocket. At liftoff, six of the solid rocket motors will also light, and the rocket will begin its ascent. It will pass Mach 1, the speed of sound, just over thirty two seconds after launch. Forty seven seconds into the flight, the rocket will pass through max-Q, when it will be subjected to maximum dynamic pressure.

Sixty three seconds after liftoff, the ground-lit solid motors will burn out, and two seconds later the three remaining solids will ignite. Three seconds after burning out, three of the ground-lit motors will be jettisoned, with the other three following suit one second later. Three seconds after the second set of ground-lit boosters separate, the rocket will begin the first of three dog-leg manoeuvres to increase the inclination of its destination orbit.

Around thirty seconds after beginning the dog-leg, the rocket will manoeuvre again to provide zero angle of attack during separation of the air-lit solid rocket motors. The motors will burn out around 129 seconds after launch, and separate two and a half seconds later, after which the rocket will begin its second dog-leg manoeuvre, which will last eighteen seconds.

Around four minutes and twenty three seconds after launch, the RS-27A will shutdown, having depleted propellent in the first stage. The vernier engines will cutoff a few seconds later. Staging will occur eight seconds after main engine cutoff, and will be followed by second stage ignition five and a half seconds later. The second stage will be powered by an AJ-10-118K engine, which will perform four burns, two before and two after spacecraft separation.

The payload fairing will separate from the rocket four seconds after second stage ignition. Two seconds later, the rocket will begin the third and final dog-leg, which will last ten seconds. Ten minutes and thirty two seconds into the launch, the second stage engine will shut down having completed its first burn, which will result in a parking orbit with a perigee of around 185 kilometres, an apogee of around 1,537 kilometres, and 54.6 degrees of inclination.

Forty two and a half minutes after launch, the second stage will restart for its second burn, which will last sixty seven seconds. Four minutes and twelve seconds after completion of the burn, the STSS-Demo SV-1 spacecraft will separate. Following a series of reorientation manoeuvres, the SV-2 spacecraft will separate seven minutes and twenty five seconds later. The satellites should separate into a circular orbit at an altitude of 1350 kilometres, inclined at 58 degrees.

Following spacecraft separation, the second stage will perform an evasive burn, and a depletion burn. The five second evasive burn will begin 108 minutes and 20 seconds after launch. Six minutes and forty seconds later, it will restart again for the depletion burn. This is expected to last around twenty six seconds, and will use excess fuel in the stage to minimise risks of it causing an explosion in orbit.

The launch will occur from Space Launch Complex 17B at Cape Canaveral, a launch pad which was first used for tests of the Thor missile in 1957. It was subsequently used by a series of Delta rockets, followed by the Delta II in 1989. It was subsequently modified to accommodate the Delta III rocket, which first flew in August 1998. All three Delta III launches occurred from SLC-17B, and the modifications made for the Delta III also allow it to support the Delta II Heavy.

Wednesday’s launch is the 145th flight of the Delta II, and marks the last US military payload on the Delta II manifest, however the launch is being conducted under a contract with NASA rather than directly through the US military. The Delta II is currently scheduled to make its next flight on 6 October, with the WorldView-2 commercial imaging satellite. The next Delta II launch from Cape Canaveral will be in 2011, with the GRAIL mission to the Moon.

Related posts:

1. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
2. Last GPS IIR satellite launched on final SLC-17A Delta II A United Launch Alliance (ULA) Delta II has become the...
3. Delta II launches with Kepler Planet-Finder Launch The Delta II launch team at the Cape Canaveral Air...

Launch Reaction:

“Congratulations to the Air Force and our mission partners in deploying this revolutionary space system that has changed the world for the better in the past 20 years,” said Jim Sponnick, vice president, Delta Product Line. “One third of the 143 successful Delta II launches were GPS satellites.

“The ULA Delta team is extremely proud to have launched this incredible constellation. During the past two decades, the system has changed how people live their lives on a daily basis. GPS has greatly improved military operations as well as numerous maritime, aircraft, civilian and business operations worldwide.”

“We have the STSS Demo launch set for September, the WorldView-2 launch scheduled for October, and several more scheduled beyond those missions. The Delta II workhorse will remain the medium class launch vehicle industry standard for years to come.”

This launch will end the Delta II’s association with the GPS programme, which has spanned twenty years and forty nine launches including today’s. GPS launches will continue with the GPS IIF series, which will use EELVs.

Launch Preview:

The GPS II-1, or USA-35, satellite was the payload for the Delta II’s maiden flight, which used the 6925 configuration and lifted off from SLC-17A on 14 February 1989. The first GPS IIA satellite was the payload for the maiden flight of the 7000 series Delta II in November 1990. All Delta II launches of GPS satellites have been successful bar one; GPS IIR-1 was lost due to a booster failure seconds after launch in January 1997.

Today’s launch will be the last Delta II to use the 7925 configuration. The first stage is an Extra-Extended Long Tank Thor, augmented during ascent by nine GEM 40 solid rocket motors.

The second stage is a Delta-K, and the third stage is a Star 48B. A standard configuration, 2.9-metre (9.5-foot) diameter, payload faring will encapsulate the satellite and upper stages during their ascent.

The first stage RS-27A main engine will ignite about two seconds before launch, along with two vernier engines which will be used to control the rocket’s roll.

Six of the solid rocket motors will light at liftoff, and burn for a little over a minute. Fifty seconds into the flight, the rocket will pass through the area of maximum dynamic pressure, max-Q.

Once the ground-lit solid motors burn out sixty three seconds after liftoff, they will remain attached for three seconds before falling away from the rocket in two groups of three, one second apart.

Around two seconds after the ground-lit solid motors burn out, but before they separate, the three air-lit motors will ignite. These will also burn for one minute.

Two minutes and twenty seconds into the flight, the rocket will perform the first of two dog-leg manoeuvres to increase the inclination of its deployment orbit.

These manoeuvres will be performed in order to reach an inclination which cannot normally be reached from Cape Canaveral due to range safety requirements, and the first will last twenty seconds.

Four minutes and twenty three seconds into the flight, the first stage main engine cutoff will occur, with the verniers following suit a few seconds later. Eight seconds after MECO, the first stage will separate, and the second stage will coast for five and a half seconds before igniting its AJ-10-118K engine to begin its first burn.

Six seconds later, the second dog-leg will be performed, this time lasting ten seconds. Twenty seconds after the second stage ignites, the payload fairing be jettisoned. At the end of its first burn, which will last six minutes and eleven seconds, the second stage engine will shut down, beginning a fifty two minute coast phase. Following this, the second stage will restart for its second burn which will last for around forty two seconds.

Fifty seconds after the second stage has completed its second burn, the third stage will be spun up to provide stabilisation during its burn. Three seconds later, it will separate from the second stage, before igniting thirty seven seconds later for an eighty-seven second burn. Following burnout of the upper stage, the vehicle will coast for just under two minutes, and then spacecraft separation will occur.

The launch will last about sixty-eight minutes from lift-off to spacecraft separation. GPS IIR-21 will be deployed into a 193 by 20,370 kilometre orbit, inclined at 40 degrees. The spacecraft will use its onboard propulsion system, which includes a Star-37FM apogee motor, to raise itself into an operational medium Earth orbit. It will replace the USA-126, or GPS IIA-26, satellite, covering Slot 3, Plane E of the GPS constellation

Around one hour and forty seven minutes after launch, the second stage will restart for a third burn. This will be a propellent depletion burn, lasting approximately thirty two seconds, and will lower the stage’s orbit to speed up its orbital decay, so that it reenters the atmosphere sooner rather than later.

Launch Complex 17A, as it was then designated, was built during the 1950s as one of three pads for the Thor IRBM test programme, the others being LC-17B and LC-18B. The first launch from the complex was the unsuccessful third test flight of the Thor DM-18, which occurred on 30 August 1957. The launch of GPS IIR-21 is the 161st launch from SLC-17A, and the 145th orbital launch attempt to use the pad.

Over the years, a number of Thor-derived rockets have used SLC-17A; the Thor DM-18, Thor-Able, Thor-Delta and Thor DSV-2D rockets, followed by the Delta A, B, C, D, E, E1, G, L, M, M6 and N, then the Delta 2000 and 3000 series, before finally both the 6000 and 7000 series Delta II. The two remaining Delta II launches from Cape Canaveral; STSS-Demo next month, and GRAIL in 2011, will use SLC-17B.

Another five launches will be made from SLC-2W at the Vandenberg Air Force Base. All remaining launches will use two-stage configurations, making this the final scheduled flight of a three-stage Delta rocket.

This will also mark the 30th and final launch of an AS-4000 satellite. The AS-4000 bus was developed by GE Astro Space, which was subsequently sold to Martin Marietta. Production was transferred to Lockheed Martin when it was formed. The AS-4000 bus was used for all twenty one GPS IIR satellites, as well as eight commercial communications satellites and NASA’s Advanced Communications Test Satellite.

This will also be the last Delta II launch from Cape Canaveral to be overseen by the US military; the remaining two launches will be overseen by NASA. The first Space Launch Squadron of the USAF is responsible for Delta II launch operations.

As the Delta II programme winds down, United Launch Alliance have been announcing job cuts. 224 employees are expected to be laid off on 15 October. The reduction in Delta II launch rates was cited as one of the main reasons for the cutbacks.

Today’s launch is the 144th flight of the Delta II. The next is currently scheduled for 16 September with STSS-Demo, the last US military payload on the Delta II manifest, which is being launched under a contract with NASA.

It is unclear what the next launch to be conducted by United Launch Alliance will be, as two Atlas launches which were scheduled for late August with the PAN satellite, and early September with a DMSP spacecraft, have both slipped to unknown dates. STSS-Demo is the next ULA launch with a confirmed date.

Related posts:

1. WorldView-2 launched via Delta II out of VAFB DigitalGlobe’s WorldView-2 satellite has been launched atop a United Launch...
2. Delta II launches penultimate GPS-IIR satellite A United Launch Alliance (ULA) Delta II rocket has launched this...
3. ULA successfully launch STSS-Demo via Delta II The United Launch Alliance (ULA) launch of a Delta II...