Atlas V launches WorldView-4 out of Vandenberg
The United Launch Alliance (ULA) Atlas V rocket – interrupted by a wildfire – finally conducted a rare commercial launch on Friday, tasked with orbiting the WorldView-4 Earth-imaging satellite in a mission from Vandenberg Air Force Base, California. The launch was set to take place in September, prior to the standdown.
Atlas V Launch:
The launch of WorldView-4 was the tenth commercial launch for the Atlas V rocket, although six of those launches were made more than ten years ago before the rocket was established as a workhorse for United States government customers.
The initial launch attempt back in September was proceeding to the final minutes of the countdown, prior to a decision to standdown due to a small ground side LH2 leak resulting in an ice ball forming on an umbilical. ULA CEO Tory Bruno noted this was outside of ULA’s historic experience, thus resulting in a scrub – for at least 24 hours – to resolve.
Later, a ULA source noted the next attempt would be 48 hours after the scrub in order to allow time to replace a Fill and Drain (F&D) valve that was deemed to be the problem during first attempt.
However, that Sunday’s attempt was called off early in the morning due to brush fires in the region. Those fires became a much larger problem during the days that followed, with large wildfires ravaging the area.
They reached within eye shot of the pad. However, responders ably managed to keep the launch site safe, with Atlas V protected inside the launch tower.
WorldView-4 was the second satellite to be launched by the Atlas V for its operator, DigitalGlobe, following WorldView-3 in August 2014.
WorldView-4 was originally constructed for GeoEye Incorporated as GeoEye-2. Lockheed Martin was awarded a contract to build the satellite in March 2010, followed in October of the same year by a contract to provide launch services. Lockheed Martin developed the Atlas V rocket.
However, in 2006 it transferred the rocket to the newly-formed United Launch Alliance (ULA), a jointly-owned venture with Boeing who transferred their Delta II and Delta IV vehicles to the company. Under this agreement, Lockheed Martin still markets the rocket to commercial customers, subcontracting the launch to ULA.
GeoEye merged with DigitalGlobe in January 2013, four months ahead of the planned launch of GeoEye-2. With DigitalGlobe’s own WorldView-3 scheduled to fly the following year, the company decided that launching both satellites in such a short timespan was unnecessary and opted to keep GeoEye-2 as a ground spare until needed in orbit.
A year later DigitalGlobe announced that due to market demand they were considering moving the launch up and that the spacecraft had been renamed WorldView-4; in late 2015 the launch was set for September 2016.
DigitalGlobe itself was formed in January 1992 as WorldView Imaging, and from 1995 to 2001 the company was named EarthWatch, before taking on its current name. The company’s first satellite, EarlyBird 1, was launched by a Start-1 rocket in December 1997. However, the spacecraft failed three days after launch.
A second satellite, Quickbird-1, was lost in a Kosmos-3M launch failure in November 2000, before Quickbird-2 successfully reached orbit atop a Delta II the following October, achieving thirteen and a quarter years of service before its retirement in January 2015.
Today, the company has four satellites in service: WorldView-1 was launched atop a Delta II 7920-10C from Vandenberg in September 2007 and was designed for a minimum of seven and a half years’ service which it has already exceeded.
WorldView-2 followed atop another Delta II in October 2009, with WorldView-3 launching on an Atlas V in August 2014.
The fourth satellite is GeoEye-1, inherited in the merger with GeoEye, which was launched by a Delta II 7420-10C in September 2008. Although GeoEye-1 has already surpassed its seven-year design life, it carries sufficient fuel for fifteen years of service.
WorldView-4 is a 2,087-kilogram (4,601 lb) satellite, based on Lockheed Martin’s LM-900 bus and LMx avionics package.
The LM-900 bus has only previously been used for two satellites: a pair of Ikonos imaging satellites operated by one of GeoEye’s predecessors – Space Imaging – which were launched by Athena-2 rockets in 1999. The first failed to achieve orbit. However, the second – Ikonos-1 – remained in service for fifteen and a half years.
It was transferred to GeoEye when the company was formed in the 2006 merger of Space Imaging and the Orbital Imaging Corporation, or OrbImage, and was still operational when transferred to DigitalGlobe in the 2013 merger – finally being decommissioned in March 2015.
In the eighteen years since its last launch, Lockheed Martin has improved on the LM-900 bus, incorporating the same avionics package used in planetary missions including the Mars Reconnaissance Orbiter, Juno and GRAIL. Lockheed Martin has also upgraded its LM-1200 bus, jointly designating the two platforms with improved avionics as the LMx series.
WorldView-4’s GIS-2 imaging systems were developed by Harris Corporation and are capable of panchromatic or multispectral observations over a 13.1-kilometre (8.1 mile, 7.1 nautical mile) swath width. Panchromatic imaging will capture light at wavelengths between 450 and 800 nanometres, with a resolution of up to 31 centimeters (12.2 inches).
In multispectral operation the satellite can sample a blue band of wavelengths between 450 and 510 nanometres, green between 510 and 580 nm, red between 655 and 690 nm and infrared between 780 and 920 nanometres. The satellite’s maximum multispectral resolution is 1.24 meters.
The WorldView-4 satellite has a design life of seven years; however it is expected to exceed this with ten to twelve years of service envisioned. The satellite will be operated in a sun-synchronous orbit at an altitude of 617 kilometers (383 miles, 333 nautical miles).
The Atlas V that launched WorldView-4, AV-062, was an Atlas V 401. The smallest Atlas V configuration, it consists of a Common Core Booster (CCB) first stage and a single-engine Centaur second stage with a four-metre payload fairing and no solid-fuelled booster rockets.
AV-062 was originally intended to launch NASA’s InSight mission to Mars in March, however efforts to repair a leak in the InSight spacecraft’s primary instrument could not be completed in time to make its 27-day launch window, necessitating a delay to 2018, the next time Earth and Mars will be aligned to facilitate placing the spacecraft into a suitable transfer orbit between the two planets.
Assembly of the Atlas V for the InSight mission was already underway, so the vehicle was kept integrated atop its launch pad in preparation for the next mission, WorldView, which was to use the same 401 configuration.
WorldView-4 was launched from Space Launch Complex 3E (SLC-3E) at the Vandenberg Air Force Base in California.
Part of a two-pad complex that was originally built as Launch Complex 1 of the US Navy’s Point Arguello facility, the pad became part of the adjacent Vandenberg Air Force Base when the sites were merged in 1964 and was subsequently renamed SLC-3E in 1967 with the complex’s other pad becoming SLC-3W.
The first launch from SLC-3E – then still part of Point Arguello – was made by an Atlas LV-3 Agena-B on 12 July 1961, the first of several Atlas-Agenas to launch from the pad.
After the Atlas-Agena the complex was used by three Atlas SLV-3 vehicles which made suborbital launches with the PRIME lifting body in 1966 and 1967, followed in 1968 by a single launch of a leftover Atlas SLV-3 with a Burner II upper stage which failed to achieve orbit. After this launch, the pad remained inactive for ten years.
Beginning in 1978, SLC-3E began to be used by the Atlas E/F rocket, based on the Atlas-E and Atlas-F missiles, to launch early Global Positioning System (GPS) satellites; followed by Atlas-H launches with first-generation Intruder ocean surveillance satellites for the National Reconnaissance Office. The pad again became inactive following the final Atlas-H launch in May 1987.
However, in the 1990s it was rebuilt for the Atlas II. Three Atlas II vehicles launched from Vandenberg; the first carrying NASA’s Terra Earth observation satellite with two subsequent launches deploying third-generation Intruder satellites for the NRO.
The Atlas V was not originally expected to launch from Vandenberg; due to the relatively limited subset of Government missions requiring a West Coast launch only the Delta IV was to have facilities there. This changed after Boeing were stripped of several launch contracts following a corporate espionage case, and the former Atlas II pad was adapted for the larger Atlas V. AV-062 will be the twelfth Atlas V to fly from SLC-3E.
The second pad at Space Launch Complex 3, SLC-3W, is no longer in use. It supported its last launch in March 1995 with the retirement of the Atlas E/F and despite conversion by SpaceX to launch Falcon 1 rockets in the mid-2000s, the pad was never used again for a launch. The Falcon launch facilities at SLC-3W have since been dismantled.
Launch of the Atlas V rocket with WorldView-4 began with ignition of the rocket’s RD-180 engine 2.7 seconds before the countdown reached zero.
Developed by Russian manufacturer NPO Energomash, the RD-180 is derived from the RD-170 series of engine developed for the Zenit rocket and burns RP-1 propellant mixed with liquid oxygen within twin combustion chambers. A single RD-180 powers the Atlas V first stage, or Common Core Booster (CCB).
Liftoff of AV-062 occurred when the thrust from the RD-180 engine exceeded the weight of the rocket; which occurred 1.1 seconds after the zero mark in the countdown.
Atlas began its ascent, making a series of pitch and yaw maneuvers beginning seventeen and a half seconds after launch to place itself on the pre-planned launch trajectory. The rocket flew south from Vandenberg along an azimuth of 185.6 degrees over the Pacific Ocean.
At 79.1 seconds into the flight the vehicle passed through Mach 1, the speed of sound, followed by the area of maximum dynamic pressure, or Max-Q, 13.4 seconds later.
Four minutes and 3.1 seconds after liftoff, the Common Core Booster cut off, having completed its role in the mission. The spent stage separated six seconds later, with the second stage engine beginning its prestart sequence.
The second stage, Centaur, is powered by a single RL10C-1 engine which burns cryogenic propellant; liquid hydrogen and liquid oxygen. Centaur ignition occurred ten seconds after stage separation.
Prior to the deployment of WorldView-4, Centaur made a single burn lasting eleven minutes and 15.9 seconds. At the start of the burn, 8.1 seconds after ignition, the rocket’s payload fairing separated from around the WorldView spacecraft.
For this mission a Long Payload Fairing (LPF), the shortest of the three four-metre fairings available, was used to encapsulate the satellite.
Separation of WorldView-4 is occurred at nineteen minutes and 15.9 seconds mission elapsed time; three minutes and 39 seconds after the end of powered flight.
The target deployment orbit is 610.46 by 628.29 kilometers (379.31 by 390.40 miles, 329.62 by 339.25 nautical miles) at an inclination of 97.96 degrees to Earth’s equator.
Centaur’s mission did not end with the separation of WorldView-4. During its second revolution around the Earth, seven smaller satellites were deployed under a mission designated Enterprise, which is sponsored by the National Reconnaissance Office. All of the secondary payloads conform the CubeSat standard.
AeroCube-8C and 8D are 1.5-unit CubeSats which form part of The Aerospace Corporation’s IMPACT mission, carrying technology demonstration experiments that include a new form of ion propulsion, materials research involving the use of carbon nanotubes for radiation shielding, and studies of the performance of solar cells.
AeroCube-8C and 8D follow the AeroCube-8A and 8B satellites launched as secondary payloads to the X-37B spaceplane last May as part of the AFSPC-5 launch.
The US Air Force Research Laboratory’s CELTEE satellite is a single-unit CubeSat which will be used to evaluate the on-orbit performance of an Enhanced Location Transponder (ELT) developed by M42 Technologies of Seattle, Washington.
The one-kilogram (2.2 lb) satellite is expected to operate for three to six months while researchers on the ground track the satellite to determine how well the transponder serves its purpose.
The AFRL’s second CubeSat aboard the mission is named Untitled 2U, or U2U, and is a two-unit CubeSat which will carry out an experiment named Electron and Globalstar Mapping – presumably indicating that its research will involve the Globalstar communication satellite network.
Preliminary results from the U2U mission are scheduled to be presented at a December conference of the American Geophysical Union.
Two 1.5-unit Prometheus satellites, developed by the Los Alamos National Laboratory, form part of an experiment into using small satellites to relay video, voice and data communications between field terminals and ground stations.
Prometheus 2A and 2B are the first members of a second-generation Prometheus constellation, building on research conducted by the eight-satellite first-generation constellation which launched aboard a Minotaur I rocket in 2013 as part of the ORS-3 mission.
Further second-generation spacecraft will be launched as secondary payloads on the maiden flight of SpaceX’s Falcon Heavy rocket, currently scheduled for next year.
The final secondary payload, Radiometer Assessment Using Vertically Aligned Nanotubes – or RAVAN – is a three-unit CubeSat built by Blue Canyon Technologies for operation by the Applied Physics Laboratory at Johns Hopkins University.
Designed for a six-month mission, the five-kilogram (11-lb) satellite will use highly light-absorbent carbon nanotubes to collect as much of the radiation emitted and reflected by the Earth as possible across the whole electromagnetic spectrum.
A radiometer will be used to measure the total radiation output of the Earth, which scientists will compare to the energy input from the sun to study the imbalance between incident and outgoing radiation – or the amount of energy retained by the Earth.
The CubeSats separated from Centaur in four groups, between two hours, eleven minutes and 45.9 seconds and two hours, twenty-five minutes and 45.9 seconds mission elapsed time.
After all seven CubeSats deployed, the Centaur is likely to fire its RL10 engine again in a disposal burn, taking itself away from the operational orbits of its spacecraft.
The final destination of the Centaur from the launch is expected to be heliocentric orbit, with the disposal burn propelling it to Earth escape trajectory.
The launch was the sixth of the year for the Atlas V rocket, following on from the successful deployment of the OSIRIS-Rex spacecraft bound for asteroid (101955) Bennu, which flew from Cape Canaveral atop an Atlas V 411.
It was the ninth launch of 2016 for United Launch Alliance, who have also launched three Delta IV vehicles.
An Atlas V launch had been scheduled for early October with the SBIRS-GEO-3 missile detection satellite. However, this mission has been delayed due to apparent concerns that the satellite uses a similar component to one that had recently failed on another satellite.
Details of the component and other satellite in question were not given, other than the satellite was not built by Lockheed Martin – the manufacturer of the SBIRS-GEO spacecraft. The concerns likely refer to the Intelsat 33e satellite whose apogee motor failed after launching on an Ariane 5 earlier this year.
Beyond SBIRS-GEO-3, ULA’s plans for the remainder of 2016 currently an Atlas V mission with NOAA’s GOES-R satellite later this month November, potentially followed by two launches in December with NROL-79 for the National Reconnaissance Office and the commercial EchoStar XIX communications satellite. A Delta IV launch will carry the eighth Wideband Global Satcom spacecraft for the US Air Force before the year is out.
(Images via ULA, WorldView, Lockheed Martin).