Viva Las Vega:

Vega will compliment her two big sisters at the European Spaceport by providing a target payload lift capability of 1,500 kg on missions to a 700-km circular orbit – payloads which would either be uneconomical riding on Soyuz or Ariane, or which require the dedicated flexibility that Vega can provide.

Arianespace’s fleet all have specific roles, with Ariane 5 optimized for large satellites on missions to a Geostationary Transfer Orbit (GTO), and Low Earth Orbits (LEO) for payloads of large mass. Soyuz is tailored for medium mass payloads for LEO and certain smaller GTO spacecraft.

The four-stage launcher is tailored to carry the growing number of small scientific spacecraft and other lighter-weight payloads under development or planned worldwide. Vega also offers configurations able to handle payloads ranging from a single satellite up to one main satellite plus six microsatellites.

Arianespace started work on the vehicle back in 2003 – as much as the origins of the concept range back to the 1990s – with ELV SpA (Italy) the lead manufacturer. The debut launch was originally targeting 2007, as the upper stage passed vibration testing in Holland, ahead of the Critical Design Review (CDR). This date continued to slip year on year.

Vega’s P80 advanced solid propellant motor first stage motor also underwent a static fire test in Kourou in 2006. This stage features a novel filament-wound casing structure – utilizing new-generation, high-quality production techniques.

The second and third stages – designated Zefiro 23 and Zefiro 9, respectively – also use solid propellant motors, while the launcher is topped off by the bi-propellant liquid upper stage (called AVUM – Attitude and Vernier Upper Module). Test firings of these motors took place between 2008 and 2009.

With launch pad ELA-1 successfully prepared for launch and the final Flight Readiness Review (FRR) providing a green light to proceed towards the 2012 flight, the vehicle which will carrying out the debut launch – known as a demonstration mission – completed integration of its three solid stages and the liquid AVUM fourth stage in Kourou.

This marked the start of the launch campaign, as the Arianespace teams installed and tested the hundred-ton solid-propellant first stage, the P80, with the Interstage-1/2 structure that links the first two stages. This was followed by the booster’s final acceptance, which included testing of the thrust vector control system. Electrical and avionics interface and functional tests were also performed.

With the 30-tonne solid-propellant second stage, the Zefiro-23, moved to the mobile gantry from the Vega Booster Storage and Preparation Building, the second stage underwent final acceptance, including testing of its thrust vector control system.

The 10-ton Zefiro-9 solid-propellant third stage was added on top of the launcher, ahead of the integration of the AVUM. The total lift-off mass of Vega will be 139 metric tons.

Vega’s first primary passenger, the LARES laser relativity satellite from Italy’s ASI space agency, has recently completed initial fit checks with the payload adapter and fairing. Six to nine small CubeSats and the ALMASat-1 from European universities have also been readied to be enclosed inside the fairing.

Integration of the “upper composite” fairing and payload is next up in the launch flow, to be followed by final checkout of the fully integrated launcher and the countdown rehearsal.

The launch window for Vega’s maiden flight, named VV01, opens on 26 January and closes in the first week of February – as much as some published launch manifest documentation claims the target date is at the end of that window.

Vega already has an interesting future, with ESA and Arianespace having already ordered four new launchers, amid studies for the launch of the LISA Pathfinder mission. The order complements the purchase of a first launcher in an agreement signed last year within the framework of the Verta contract, covering the five launches that follow Vega’s qualification flight.

The studies for the launch of the LISA Pathfinder scientific satellite of ESA, using a Vega launcher from the Verta batch, started at the end of September. The mission is scheduled for a launch window from October 2013 to September 2014.

Vega will also carry out the launch of ESA’s IXV (Intermediate eXperimental Vehicle), which is now into a detailed planning stage, a major step towards the spacecraft’s projected 2014 flight. (L2 Link to 15 Presentations on IXV)

Launched into a suborbital trajectory from Kourou, the IXV will return to Earth as if from a low-orbit mission, allowing for the testing and qualification of new critical technologies for future reentry vehicle concepts.

During it mission, the vehicle will attain an altitude of around 450 km, allowing it to reach a velocity of 7.5 km/s on entering the atmosphere and will collect a large amount of data during its hypersonic and supersonic flight, while it is being controlled by thrusters and aerodynamic flaps.

IXV will then descend by parachute and land in the Pacific Ocean to await recovery and analysis.

(Images via Arianespace, ESA, L2)

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Soyuz Mission:

This was the second Soyuz to launch from the newly constructed launch site at Kourou, following the successful mission to loft two European “Galileo” navigation satellites into orbit via the Soyuz ST-B.

The veteran Soyuz launch vehicle is a descendent of the R-7 Semyorka, the world’s first intercontinental ballistic missile. The R-7 was designed by Sergei Korolev, and first flew in 1957. A modified version was used to launch the first satellite, Sputnik 1, on 4 October of that year.

The R-7 formed the basis for the Luna, Vostok, Voskhod, Molniya and Soyuz families of rockets, and to date all Soviet and Russian manned spaceflights have been launched using rockets derived from the R-7.

The Soyuz, which first flew in 1966, was a modification of the Voskhod rocket featuring an upgraded and lighter telemetry system, and more fuel efficient engines. It was initially used to launch only Soyuz spacecraft; however with the introduction of the Soyuz-U in 1973 it began to launch other satellites as well.

The Soyuz-U, which remains in service, is the most-flown orbital launch system ever developed, having made around 750 flights to date, plus around 90 more in the Soyuz-U2 configuration optimised to use synthetic propellant.

The Soyuz-2 was developed from the older Soyuz models, and features digital flight control systems and modernised engines. It first flew in 2004. Two variants are currently in service; the Soyuz-2-1a, and the Soyuz-2-1b which features an RD-0124 third stage engine which provides additional thrust. The RD-0124 was declared operational on 3 May 2011.

A third configuration, the Soyuz-2-1v, is currently under development and is expected to make its maiden flight next year. It features an NK-33 engine in place of the RD-108A used on the core stages of the other configurations, and does not include the strapon boosters used by other configurations.

The Soyuz-2 forms the basis for the Soyuz-ST rocket, which has been optimised to fly from Kourou, and also incorporates a flight termination system and a modified telemetry system.

The vehicle consists of four boosters (first stage), a central core (second stage), a third stage, and the restartable Fregat upper stage (fourth stage). Each vehicle also includes a payload adapter/dispenser and fairing.

The inaugural flight of the upgraded Soyuz 2-1b launch vehicle was successfully performed on December 27, 2006, launching the Corot scientific spacecraft for the French Centre National d’Etudes Spatiales.

As part of the Soyuz’ upgrades for its operations from the Spaceport, the launcher’s flight control system is modernized with a digital control system. This system incorporates a digital computer and inertial measurement unit that are based on proven technology – giving the Soyuz improved navigation accuracy and control capability.

The new digital control system provides a more flexible and efficient attitude control system, and it gives the additional flight control authority required when the new, enlarged Soyuz ST payload fairing is installed on the vehicle. In addition, it improves flight accuracy for the Soyuz’ first three stages, and provides the ability to perform in-flight roll maneuvers as well as in-plane yaw steering (dog-leg) maneuvers.

For this Soyuz – designated VS02 in Arianespace’s launcher family numbering sequence – the mixed payload consisted of France’s Pléiades 1 and the Chilean SSOT satellites for civilian and defense image gathering, along with four French ELISA micro-satellite demonstrators for defense-related electronic intelligence gathering (ELINT).
 
Pléiades 1 was deployed 55 minutes after Soyuz’ liftoff, followed four minutes later by the simultaneous release of all ELISA satellites. Completing the mission was the separation of SSOT, which occurred 3 hours, 26 minutes after liftoff.

France’s 970-kg Pléiades 1 dual-use imaging satellite and the 117-kg Chilean SSOT multi-role observation spacecraft, along with a cluster of four French ELISA demonstrator satellites for defense-related electronic intelligence gathering (ELINT), which weigh 120 kg each, marked a complicated mission profile for Arianespace.

These payloads were released into Sun-synchronous orbits in a multi-step process during the flight, involving the Soyuz’ Fregat upper stage carrying four propulsion burns, with a fifth to deorbit the stage.

The mission was Arianespace’s year-ending flight at the Spaceport, and comes less than two months after the company’s historic maiden launch of Soyuz from French Guiana in October. Also scheduled in 2011 is another Soyuz launch at Baikonur Cosmodrome with six Globalstar second-generation satellites, which is scheduled during the week of December 25 and will be conducted on behalf of Arianespace by its Starsem affiliate.

To date, Arianespace has logged seven missions in 2011. The five flights with its heavy-lift Ariane 5 during the year orbited eight telecommunications satellites (Arabsat-5C, ASTRA 1N, BSAT-3c/JCSAT-110R, GSAT-8, Intelsat New Dawn, SES-2, ST-2 and Yahsat Y1A), along with an Automated Transfer Vehicle for servicing of the International Space Station. 

The other two launches were Soyuz missions, one operating from Baikonur Cosmodrome with six of the Globalstar second-generation satellites, and Arianespace’s maiden flight of Soyuz from the Spaceport, which lofted two Galileo IOV (In-Orbit Validation) navigation satellites.

(Images via Arianespace)

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Thursday’s Scrub:

A ground support system leak during third stage fueling of the Soyuz launcher was the cause of the delay for this medium-lift vehicle’s inaugural flight from French Guiana. Such issues are not uncommon, as seen during Ariane 5 countdowns.

Arianespace Chairman and CEO Jean-Yves Le Gall said the leak was in a launch pad pneumatic system that activates the pre-planned disconnection of fueling lines to Soyuz’ third stage before the vehicle lifts off.

“During the final phase of third stage fueling, there apparently was a change in pressure in this pneumatic system, and we observed the unplanned disconnection of the two connectors that enable the fueling of Soyuz’ third stage with liquid oxygen and kerosene,” Le Gall said in a statement after the scrub.

“The problem apparently is due to a valve leak in this pneumatic system, and we have taken the decision to empty the launcher and replace the valve.”

Le Gall underscored that the identified anomaly is in the ground-based pneumatic system, not on the launch vehicle.

Fueling of the Soyuz is performed inside the mobile service gantry, which continues to remain in place on the launch pad. The launcher and its payload of two Galileo IOV (In-Orbit Validation) satellites are in a safe mode, as is the ELS launch site.

With the valve in question soon replaced, a decision to aim for the next attempt – on Friday – was made, with the lift-off time moving four minutes earlier to 10:30am GMT.

Soyuz at CSG – The Launch Site:

Construction of the launch site began in 2007, as Arianespace advanced their plans to add two launch vehicles to their family. With Ariane 5 continuing to be the flagship in Kourou, Arianespace are first debuting the veteran Soyuz launcher, prior to including the smaller Vega launch vehicle next year.

The Spaceport’s Soyuz launch site combines the proven design elements from the long-existing site at Baikonur Cosmodrome with satellite integration procedures that are in concert with the spacecraft processing used for Ariane missions.

Located 12 kilometers northwest from the existing Ariane 5 launch complex, the new Soyuz facility extends the Spaceport’s operational zone further up the French Guiana coastline.

The launch vehicle’s assembly building is 92 meters long, 41 meters wide, and 22 meters tall, allowing the vehicle to be assembles horizontally, prior to rolling out to the launch site, which is configured after the Russian Baikonur and Plesetsk Cosmodromes, albeit with a new mobile launch service tower.

The Soyuz’ transfer to the Spaceport’s launch zone is performed with the launcher riding horizontally atop a transporter/erector rail car.  Soyuz was then raised into position on the pad, and in contrast with the Baikonur Cosmodrome processing flow, is protected by a gantry that moves into place for payload integration.

Soyuz at CSG – The Launch Vehicle:

The more powerful Soyuz-ST configuration will be the standard version launched from French Guiana, with the additional performance of the Soyuz ST-B variant – including a Fregat-MT upper stage – being used to deliver the Galileo IOV satellites into their final circular 23,222 km orbit.

The veteran Soyuz launch vehicle is a descendent of the R-7 Semyorka, the world’s first intercontinental ballistic missile. The R-7 was designed by Sergei Korolev, and first flew in 1957. A modified version was used to launch the first satellite, Sputnik 1, on 4 October of that year.

The R-7 formed the basis for the Luna, Vostok, Voskhod, Molniya and Soyuz families of rockets, and to date all Soviet and Russian manned spaceflights have been launched using rockets derived from the R-7.

The Soyuz, which first flew in 1966, was a modification of the Voskhod rocket featuring an upgraded and lighter telemetry system, and more fuel efficient engines. It was initially used to launch only Soyuz spacecraft; however with the introduction of the Soyuz-U in 1973 it began to launch other satellites as well.

The Soyuz-U, which remains in service, is the most-flown orbital launch system ever developed, having made around 750 flights to date, plus around 90 more in the Soyuz-U2 configuration optimised to use synthetic propellant.

The Soyuz-2 was developed from the older Soyuz models, and features digital flight control systems and modernised engines. It first flew in 2004. Two variants are currently in service; the Soyuz-2-1a, and the Soyuz-2-1b which features an RD-0124 third stage engine which provides additional thrust. The RD-0124 was declared operational on 3 May 2011.

A third configuration, the Soyuz-2-1v, is currently under development and is expected to make its maiden flight next year. It features an NK-33 engine in place of the RD-108A used on the core stages of the other configurations, and does not include the strapon boosters used by other configurations.

The Soyuz-2 forms the basis for the Soyuz-ST rocket, which is making its maiden flight during Thursday’s launch. The Soyuz-ST is optimised to fly from Kourou, and also incorporates a flight termination system and a modified telemetry system.

With the Soyuz ST-B utilizing the RD-0124 third stage engine, an additional 34 seconds of specific impulse (Isp) will significantly increase the vehicle’s overall launch performance.

Click here for other Soyuz related articles: http://www.nasaspaceflight.com/tag/soyuz/

The RD-0124 is a staged-combustion engine powered by a multi-stage turbopump, which is spun by gas from combustion of the main propellants in a gas generator. These oxygen-rich combustion gases are recovered to feed the four main combustion chambers where kerosene – coming from the regenerative cooling circuit – is injected.

Attitude control is provided by main engine activation along one axis in two planes. Liquid oxygen (LOX) and kerosene tanks are pressurized by the heating and evaporation of helium coming from storage vessels located in the LOX tank. Avionics for the Soyuz launcher are carried in the vehicle’s third stage, and are located in an intermediate bay between the oxidizer and fuel tanks.

As part of the Soyuz’ upgrades for its operations from the Spaceport, the launcher’s flight control system is modernized with a digital control system.  This system incorporates a digital computer and inertial measurement unit that are based on proven technology – giving the Soyuz improved navigation accuracy and control capability.

The new digital control system provides a more flexible and efficient attitude control system, and it gives the additional flight control authority required when the new, enlarged Soyuz ST payload fairing is installed on the vehicle.  In addition, it improves flight accuracy for the Soyuz’ first three stages, and provides the ability to perform in-flight roll maneuvers as well as in-plane yaw steering (dog-leg) maneuvers.

The new Soyuz fairing has a diameter of 4.11 meters and an overall length of 11.4 meters – enabling it to accommodate the full range of payloads in the launch vehicle’s performance category. Arianespace is planning to further enhance the Soyuz’ mission flexibility with the development of a structure to accommodate small secondary payloads.

Called the ASAP-S, this system continues the auxiliary platform concept previously developed for Ariane missions, which have enabled “piggyback” passengers to be flown for the past 20-plus years.

The ASAP-S has external positions for four micro-satellites, along with volume inside the center structure for a fifth payload. The ASAP-S’ external configuration accommodates spacecraft weighing up to 200 kg, while the internal position is designed to accept a payload with a maximum mass of 400 kg.

The Fregat upper stage is an autonomous and flexible upper stage designed to operate as an orbital vehicle.  Flight qualified in 2000, it extends the Soyuz launcher’s capability to provide access to a full range of orbits (medium-Earth orbit, Sun-synchronous orbit, geostationary transfer orbit, and Earth escape trajectories).

Fregat consists of six spherical tanks arrayed in a circle (four for propellant, two containing the avionics), with trusses passing through the tanks to provide structural support. The stage is independent from the Soyuz’ lower three stages, having its own guidance, navigation, control, tracking, and telemetry systems.

The Fregat uses storable propellants (UDMH/NTO) and can be restarted up to 20 times in flight – enabling it to carry out complex mission profiles. It can provide 3-axis stabilization or perform a spin-up of the spacecraft payload.
The Fregat first flew in 2000, and has been used on Soyuz-U, Soyuz-FG, Soyuz-2 and Zenit rockets.

Soyuz in CSG – The Passengers:

This launch marks the first orbital elements of Europe’s global satellite navigation system. The four satellites – both launched by Soyuz, the second of which will launch next year – are called the Galileo In-Orbit Validation (IOV) satellites, will form the operational nucleus of the full 30-satellite constellation.

Fully representative of the others that will follow them into orbit, these first four IOV satellites will prove that the satellites and ground segment meet many of Galileo’s requirements and will validate the system’s design in advance of completing and launching the rest of the constellation.

The 700 kgs birds sport two Passive Hydrogen Maser atomic clocks; two Rubidium atomic clocks; Clock monitoring and control unit; Navigation signal generator unit; L-band antenna for navigation signal transmission, C-band antenna for uplink signal detection, two S-band antennas for telemetry and telecommands; Search and rescue antenna.

Galileo’s highly-accurate atomic clocks are at the heart of the system. Each satellite emits a signal containing the time it was transmitted and the satellite’s orbital position.

The very first atomic clock, developed in England in 1955, was the size of a room. For satellite navigation, the challenge was coming up with a design that was compact and robust enough to fly in space.

Based on ESA research and development dating back to the early 1990s, two separate atomic clock technologies have been developed and qualified in Europe, then proved suitable for the harsh environment of space by the two GIOVE missions.

GIOVE-A launched on a Soyuz rocket from Baikonur Cosmodrome in Kazakhstan on 28 December, 2005, followed by GIOVE-B – again on a Soyuz rocket from Baikonur – on 27 April, 2008.

These two clocks are the Passive hydrogen maser clock and the Rubidium clock, which need to be synchronised regularly with a network of even more stable ground-based reference clocks. These include clocks based on the caesium frequency standard, which show a far better long-term stability than rubidium or passive hydrogen maser clocks.

Control Centers are located with CNES in Toulouse, France with the support of ESOC in Darmstadt, Germany for Launch and Early Operations Phase (LEOP). Satellite control transferring to Oberpfaffenhofen Galileo Control Centre in Germany while Redu in Belgium performs the In-Orbit Test campaign.

Thursday’s 3 hour, 49 minute flight will deploy the two Galileo satellites into a circular medium-Earth orbit at an altitude of 23,222 km, inclined 54.7 degrees.

(Images via ESA, Arianespace and Roscosmos).

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Ariane 5 ECA Launch Overview:

The Ariane 5 ECA (Cryogenic Evolution type A) – the most powerful version in the Ariane 5 range - was used for this flight.

The Ariane 5 ECA is an improved Ariane 5 Generic launcher. Although it has the same general architecture, a number of major changes were made to the basic structure of the Ariane 5 Generic version to increase thrust and enable it to carry heavier payloads into orbit.

Designed to place payloads weighing up to 9.6 tonnes into GTO, this increased capacity allows the Ariane 5 ECA to handle dual launches of very large satellites.

As Arianespace prepares for the expansion of its launcher family with the introduction of Soyuz and Vega at the Spaceport, the company has adopted a new numbering system to identify its missions with these three vehicles.

Ariane 5 flights will carry the “VA” designation, followed by the flight number.  The “V” is for “vol,” the French word for “flight,” while the “A” represents the use of an Ariane launch vehicle.  As a result, this latest mission will carry the “VA204″ reference, for the 204th launch of an Ariane since this family of vehicles began operations in 1979.

With the introduction of Soyuz at the Spaceport in 2011 – starting with the launch of the Galileo IOV-M1 satellites – Arianespace missions from South America with the medium-lift workhorse launcher will be designated “VS,” while flights with the lightweight Vega vehicle are to be referenced as “VV.”

SES-2 was positioned on the launcher’s core section as the lower payload, allowing the “stack” to be completed with installation of the Arabsat-5C/SYLDA/fairing combination atop it.

During the flight sequence, the payload fairing will be jettisoned first, followed by deployment of Arabsat-5C. The SYLDA dispenser is then released, allowing the subsequent separation of SES-2 to complete the Arianespace mission.

The multi-mission Arabsat-5C was built for the Arab Satellite Communications Organization (Arabsat), and is to provide capacity in both the C- and Ka-bands for a range of communications services.  To be operated from Arabsat’s 20 deg. East orbital position.

Arabsat-5C was built by EADS Astrium and Thales Alenia Space in a joint program for the satellite’s assembly and in-orbit delivery.  As the lead partner, Astrium supplied the Eurostar E3000 platform, with responsibility for assembling and testing the spacecraft. Thales Alenia Space designed and built the communications payload, which integrates C-band and Ka-band transponders.

The spacecraft has an estimated launch mass of 4,630 kg.

Its SES-2 co-passenger for the Ariane 5 flight was built by Orbital Sciences Corporation of the U.S. for SES WORLD SKIES, and is a hybrid C- and Ku-band spacecraft that will serve North America from an orbital slot of 87 deg. West. 

This platform has an estimated mass at liftoff of 3,152 kg., and it also carries the Commercially Hosted InfraRed Payload (CHIRP) for the U.S. Air Force – which integrates a wide-field of view sensor in the satellite.

The SES-2 satellite is based on Orbital’s GEOStar 2.4 bus, the company’s largest and most powerful communications satellite.  It carries 24 active C-band and 24 Ku-band transponders of 36 MHz capacity.  Six of the channels in each band can be cross-strapped to the opposite band, enabling new service capability.

The SES-2 satellite will generate approximately 5.0 kilowatts of payload power and will have two 2.3 meter deployable reflectors.

“We are looking forward to the upcoming launch and the completion of the in-orbit testing of the SES-2 spacecraft for our customer,” said Mr. Christopher Richmond, Orbital’s Senior Vice President and head of its communications satellite business unit.

“SES-2 will join four other Orbital-built GEOStar 2 spacecraft in the SES fleet, including SES-1, SES-3, NSS-9 and AMC-21, all of which continue to operate with high reliability, enabling SES to provide communications services to its customers around the world.”

CHIRP program manager Brent Armand added, “Orbital’s critical role in establishing the contract framework, the engineering processes and procedures, and the standard hosted payload interface to be first used by CHIRP, is helping pave the way for a new business value proposition for our government and international customers. 

“Taking advantage of the regularity and reliability of the commercial space industry to deploy new-generation technologies in a timely way and at an affordable total mission cost is becoming an attractive option for government space mission planners.”

The flight had been delayed for supplementary checks on the engine that powers Ariane 5′s cryogenic upper stage, which were performed as part of Arianespace’s commitment to quality and reliability.

“As we do not tolerate any defect on our launchers, there was no hesitation on our part in delaying this upcoming flight to ensure the highest level of quality for a successful mission,” said Arianespace Chairman & CEO Jean-Yves Le Gall.

“With the launch sector’s ‘devastation’ caused by mission failures of other vehicles, Ariane 5 stands out with its track record of 45 consecutive successes.”

The launch suffered one further 24 hour delay due to industrial action in the local area.

(Images via Arianespace)

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July Scrub:

All was looking good for the latest Arianespace mission until the countdown clock turned red with just under two minutes remaining in the countdown.

Although Arianespace Chairman & CEO Jean-Yves Le Gall initially said it was hoped the problem would be resolved within 15 minutes, he returned to inform the audience in the launch control center that the vehicle wouldn’t be launching within the allocated window.

Mr Le Gall also confirmed the countdown was stopped following an indication that a liquid hydrogen valve had not closed properly in the ground system network leading to Ariane 5’s core cryogenic stage. 

After initial troubleshooting did not fully identify the cause of this anomaly, thus a the mission postponement decision was made.

Following evaluations, the vehicle returned to the Assembly Building for repairs, which will result in a delay to the mission by what turned out to be over a month – after it was initally thought the mission would only have to wait another two weeks.

This latest attempt was set to take place on Friday night (August 5). However, poor weather in the region forced managers to delay for a further 24 hours.

Ariane 5 ECA Launch Overview:

The Ariane 5 ECA (Cryogenic Evolution type A) – the most powerful version in the Ariane 5 range – was used for this flight.

The Ariane 5 ECA is an improved Ariane 5 Generic launcher. Although it has the same general architecture, a number of major changes were made to the basic structure of the Ariane 5 Generic version to increase thrust and enable it to carry heavier payloads into orbit.

Designed to place payloads weighing up to 9.6 tonnes into GTO, this increased capacity allows the Ariane 5 ECA to handle dual launches of very large satellites.

As Arianespace prepares for the expansion of its launcher family with the introduction of Soyuz and Vega at the Spaceport, the company has adopted a new numbering system to identify its missions with these three vehicles.

Ariane 5 flights will carry the “VA” designation, followed by the flight number.  The “V” is for “vol,” the French word for “flight,” while the “A” represents the use of an Ariane launch vehicle.  As a result, this latest mission will carry the “VA203″ reference, for the 203rd launch of an Ariane since this family of vehicles began operations in 1979.

With the introduction of Soyuz at the Spaceport in 2011, Arianespace missions from South America with the medium-lift workhorse launcher will be designated “VS,” while flights with the lightweight Vega vehicle are to be referenced as “VV.”

Ariane 5 carried a total estimated payload of 9,095 kg. – including 8,240 kg. for the ASTRA 1N and BSAT-3c/JCSAT-110R satellite passengers. ASTRA 1N is located in the upper position of Ariane 5′s payload “stack” and will be released first during the 38-minute mission.

The ASTRA 1N spacecraft, was built by EADS Astrium in Toulouse, France for the Luxembourg-based operator SES Astra. 

Based on Astrium’s Eurostar E3000 platform, ASTRA 1N has an estimated liftoff mass of 5,350 kg. and is fitted with 52 active Ku-band transponders.  It initially is to deliver interim capacity from an orbital position of 28.2 deg. East, and subsequently will move to SES ASTRA’s prime location at 19.2 deg. East for primary and backup services during a designed operational lifetime of 15 years.

BSAT-3c/JCSAT-110R was manufactured by Lockheed Martin Commercial Space Systems at its plant in Newtown, Pennsylvania as part of a turnkey contract for Japanese operators B-SAT Corporation and SKY Perfect JSAT Corporation. 

Produced using an A2100 A platform, this satellite will weigh approximately 2,910 kg. at launch, and is to be positioned at 110 deg. East longitude in geostationary orbit, and offers a design life exceeding 16 years. BSAT-3c/JCSAT-110R is fitted with 24 active Ku-band transponders, and is primarily designed to provide direct TV broadcast links for all of Japan.

“We were extremely pleased to collaborate with two valued customers on this program,” said Lockheed Martin Commercial Space Systems president Joseph Rickers. “Once BSAT-3c/JCSAT-110R has been successfully launched and handed over for service, we are confident that both B-SAT and SKY Perfect JSAT will benefit tremendously from the enhanced capabilities that BSAT-3c/JCSAT-110R will bring to their respective fleets.”

The Lockheed Martin A2100 geosynchronous spacecraft series is designed to meet a wide variety of telecommunications needs including Ka-band broadband and broadcast services, fixed satellite services in C-band and Ku-band, high-power direct broadcast services using the Ku-band frequency spectrum and mobile satellite services using UHF, L-band, and S-band payloads.

The modular design features simplified construction, increased on-orbit reliability and reduced weight and cost. The A2100 design accommodates a large range of communication payloads and serves as the platform for critical government communications programs, including the Advanced Extremely High Frequency and Mobile User Objective System satellites.

The A2100 spacecraft can also be configured for missions other than communication. It has been adapted for Lockheed Martin’s Geostationary Operational Environmental Satellite Series-R earth observing mission and serves as the spacecraft platform for Lockheed Martin’s GPS III program.

Click here for other Ariane Articles: http://www.nasaspaceflight.com/tag/ariane-5/

Saturday’s mission follows Arianespace’s previous Ariane 5 flights in 2011 that orbited the ST-2 and GSAT-8 telecommunications satellites on May 20; the Yahsat Y1A and Intelsat New Dawn relay spacecraft on April 22; and the Johannes Kepler Automated Transfer Vehicle for servicing of the International Space Station on February 16.

(Images via Arianespace).

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ATV-2 mission summary:

The European Space Agency (ESA) owned ATV-2 launched to the ISS from the Kourou space center in French Guiana atop an Ariane 5 rocket on 16th February this year. Following an eight day free-flight, the uncrewed resupply vessel docked autonomously to the ISS at the Service Module (SM) Aft port on 24th February, just hours prior to the launch of Space Shuttle Discovery on the STS-133 mission.

ATV-2 delivered seven tonnes of supplies to the ISS, consisting of 1,170 kg of dry cargo, 100 kg of oxygen, 851 kg of propellants to refill the ISS’ tanks, and 4,535 kg of fuel for ISS reboosts.

The reboost fuel was used to perform numerous ISS orbit corrections and attitude control assistances during ATV-2′s stay at the station, notably on 2nd April when the spacecraft maneuvered the station to avoid a collision with some orbital debris. But by far the biggest use of reboost fuel was the four “big boosts” conducted in stages throughout this past week.

The goal of the “big boosts” was to raise the ISS to its new operating altitude for the post-Shuttle era. With the US Segment of the ISS now complete, Space Shuttles no longer need to bring large, heavy components up to the ISS, and so the ISS can now be operated at a higher altitude where less atmospheric particles exist, resulting in less drag being placed on the station.

This reduction in drag will reduce the amount of ISS reboosts that will be needed in future, meaning that Visiting Vehicles (VVs) will be able to carry less reboost propellant, and thus more dry cargo to the station.

It is estimated that the higher operating altitude of the ISS will reduce the requirements for reboost propellant from 19,000 pounds per year down to 8,000 pounds per year, resulting in 11,000 pounds of extra VV payload capacity each year, although this amount may not directly translate into an increase in dry cargo capacity since VVs will also need to use slightly more fuel to rendezvous with the ISS at its higher altitude.

Overall though, the higher operating altitude will result in an increased amount of dry cargo capacity for ISS VVs, which will further help to keep the ISS resupplied in the post-Shuttle era. Although one Space Shuttle mission still remains on the manifest (STS-135 in July), the higher operating altitude of the ISS will not be an issue, and any reduction in Shuttle payload capacity is negligible.

The first of the “big boosts” kicked off last Sunday (12th June), which saw two reboosts occur on the same day. The first reboost lasted 36 minutes 6 seconds, which resulted in a change in velocity (delta-V) of 5.2 m/s, and a mean altitude gain of 9.2 km.

The second reboost occurred roughly 3 hours 30 minutes later, and lasted 40 minutes 12 seconds, which resulted in a delta-V of 5.8 m/s and a mean altitude gain of 10.1 km. Combined together, the total reboost duration was 1 hour 16 minutes 18 seconds, which gave a delta-V of 11 m/s, and a mean altitude gain of 19.3 km.

Instead of conducting one large reboost, two reboosts were necessary with a pause in between, due to “how ATV’s fuel system pumps propellant”, and to let the reboost engines cool down. However, the two reboosts caused an issue with power balances, since the two reboosts drew more power from the batteries than expected.

The high solar beta angle (where the sun hits the ISS side-on) that was in effect at the time caused shadowing of the station’s and ATV-2′s solar arrays, and prevented the batteries from being recharged at their normal rate. Thus, lower than expected battery charge levels were incurred due to the higher power draw and lower recharge rate.

Following a meeting of the ISS Mission Management Team (IMMT), the original plan to conduct another two reboosts on Wednesday 15th June was changed. Under the new plan, only one reboost would be conducted on Wednesday 15th June, with the second being performed on Friday 17th June, and a third back-up opportunity being available on Saturday 18th June.

To aid battery recharge rates in the high beta angle period, the 4B and 2B BGAs (Beta Gimbal Assemblies), which control the beta rotation of the station’s solar arrays, would be kept in Autotrack, allowing them to track the Sun.

Wednesday’s reboost was performed nominally, with a duration of 39 minutes 40 seconds, a delta-V of 5.84 m/s, and a mean altitude gain of 10.2 km. Friday’s fourth and final reboost also went off without a hitch, with a duration of 26 minutes 53 seconds, a delta-V of 3.96 m/s, and a mean altitude gain  of 6.9 km.

In total, the four ATV-2 “big boosts” lasted 2 hours 22 minutes 11 seconds, and resulted in a delta-V of 20.8 m/s, and a staggering mean altitude gain of 36.4 km. The ISS is now at a mean altitude of 381 km, with a 384 km apogee (highest point) and 379.1 km perigee (lowest point). In 12 years of operation, the ISS has never been this high above the Earth.

ATVs are the only vehicles capable of performing such massive reboosts due to their large propellant capability and their four mighty Orbit Correction System (OCS) engines, which consumed 1,400 kg of propellant during the four reboosts.

According to NASA, ATV-2 performed the reboosts “with an outstanding precision that has never been reached for such a maneuver since the Apollo TLI (Trans-Lunar Injection) burns by the Saturn V S-IVB stage”.

The required amount of propellants were successfully transferred to the ISS’ fuel tanks during ATV-2′s stay at the station, and 78 kg of the 100kg of oxygen (O2) delivered by ATV-2 was also released into the ISS’ atmosphere.

However, the remaining 22 kg of O2 was not able to be transferred to the ISS, due to a failed fan inside ATV-2 which caused safety concerns since it was not able to cool equipment used in O2 transfers.

This will not adversely affect the O2 supplies aboard the ISS, despite recent concerns relating to the failure of Russia’s Elektron O2 generator, since during Space Shuttle Endeavour’s recent visit to the station, 10 pounds of O2 was transferred to the ISS from Endeavour, and the US Segment Oxygen Generation System (OGS) was successfully repaired. Also, the Elektron has since been successfully repaired by the Russian crewmembers.

Click here for ISS news articles: http://www.nasaspaceflight.com/tag/iss/

ATV-2 undocking and de-orbit:

Now depleted of all useful dry cargo, propellants and oxygen, ATV-2 was filled with 1,200 kg of trash, which according to an ISS stowage status document obtained by L2, includes 6 RFTAs (Recycle Filter Tank Assemblies), the ESA flywheel experiment, ATV-2 and STS-134/ULF-6 foam, common trash, and payload trash.

Hatch closure between ATV-2 and the ISS occurred Sunday, and ATV-2 undocked from the ISS at 2:48:21 PM GMT on Monday. ATV-2 conducted a separation burn using its thrusters shortly after undocking, at 2:51 PM GMT.

Following a free-flight for just over one day, an orbit-lowering burn was conducted on Tuesday 21st June at 5:07 PM GMT. The de-orbit burn followed roughly three hours later at 8:05 PM GMT, whereupon the ten tonne ATV-2 plummeted through Earth’s atmosphere as a giant fireball, eventually disintegrating under the intense heat.

Surviving parts of ATV-2 splashed down in a remote area of the Pacific Ocean around 8:52 PM GMT. A no-fly zone was in place above the debris fallout zone, and sea traffic was warned to keep out of the area.

Aboard ATV-2 during re-entry was the second Re-Entry Breakup Recorder (REBR), the spacecraft equivalent of a black box, designed to record data on the physics of re-entry disintegrations and send the data to a satellite prior to anticipated destruction upon splashdown in the Ocean. 

Click here for ATV news articles: http://www.nasaspaceflight.com/tag/ATV/

The first REBR flew on Japan’s HTV-2 (H-II Transfer Vehicle-2) during its re-entry in March this year, and performed well above expectations, managing to survive re-entry and splashdown intact and still send signals while floating in the Ocean.

Progress M-11M launch and docking:

Roughly 5 hours 25 minutes prior to ATV-2′s de-orbit burn, Russia’s uncrewed Progress M-11M/43P spacecraft blasted off atop a Soyuz-U rocket from the Baikonur Cosmodrome in Kazakhstan, on a resupply mission to the ISS. Liftoff was at 2:38:18 PM GMT on Tuesday.

In the short 5 hour 15 minute period between Progress M-11M’s launch and ATV-2′s de-orbit burn, two VVs will be free-flying in space together, albeit in different orbits.

Following a two day free flight, Progress M-11M will autonomously dock to ATV-2′s recently vacated docking port, Service Module (SM) Aft, on Thursday 23rd June at 4:35 PM GMT. Progress M-11M will remain attached to SM Aft until 29th August, whereupon it will undock and head towards the same fiery demise as ATV-2.

(Images via ESA and L2 ATV documentation). For other ATV-2 content, visit the excellent ATV-2 blog by ESA: http://blogs.esa.int/atv

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Ariane 5 ECA Launch:

The Ariane 5 ECA (Cryogenic Evolution type A) – the most powerful version in the Ariane 5 range – is was used for this flight.

The Ariane 5 ECA is an improved Ariane 5 Generic launcher. Although it has the same general architecture, a number of major changes were made to the basic structure of the Ariane 5 Generic version to increase thrust and enable it to carry heavier payloads into orbit.

Designed to place payloads weighing up to 9.6 tonnes into GTO, this increased capacity allows the Ariane 5 ECA to handle dual launches of very large satellites.

As Arianespace prepares for the expansion of its launcher family with the introduction of Soyuz and Vega at the Spaceport, the company has adopted a new numbering system to identify its missions with these three vehicles. 

Ariane 5 flights will carry the “VA” designation, followed by the flight number.  The “V” is for “vol,” the French word for “flight,” while the “A” represents the use of an Ariane launch vehicle.  As a result, the mission with ST-2 and GSAT-8 will carry the “VA202″ reference, for the 202nd launch of an Ariane since this family of vehicles began operations in 1979.

With the introduction of Soyuz at the Spaceport in 2011, Arianespace missions from South America with the medium-lift workhorse launcher will be designated “VS,” while flights with the lightweight Vega vehicle are to be referenced as “VV.”

The new Vega small launcher took its the next step towards its maiden flight later this year with completion of mechanical testing of a full-scale mock-up at the Spaceport in April.

ST-2 will be deployed first during the 31-minute flight sequence of Ariane 5.  Built by Japan’s Mitsubishi Electric Company, the satellite will be operated by the ST-2 Satellite Ventures joint company of Singapore Telecommunications Ltd (SingTel) and Taiwan’s Chunghwa Telecom Company Ltd.  

With an estimated liftoff mass of 5,090 kg., ST-2 will provide Ku- and C-band relay services for the delivery of IP-based fixed and mobile, voice and data transmission satellite services to businesses – especially direct broadcast TV operators and maritime companies in Asia and the Middle East.

Mitsubishi Electric has been a leading manufacturer contributing to space research and development in Japan mainly for Japan Aerospace eXploration Agency (JAXA), as well as participating in the development of more than 440 international satellites as major subcontractor.

ST-2 makes Mitsubishi Electric the first Japanese satellite manufacturer to enter the commercial communications satellite market outside Japan using DS2000, Mitsubishi Electric’s satellite bus platform currently with a track record of five satellites in orbit.

The DS2000 bus was evolved from the Engineering Test Satellite-8 (ETS-8) developed for NASDA (the National Space Development Agency of Japan), and also was used for the SKY Perfect JSAT Corporation’s Superbird-C2 telecom spacecraft, which was orbited by Arianespace in August 2008 on an Ariane 5.

The other passenger in Ariane 5′s dual-payload “stack” is GSAT-8, which was built by the Indian Space Research Organisation (ISRO).  This spacecraft weighs approximately 3,100 kg. for liftoff, and carries 24 transponders to augment India’s Ku-band relay capabilities – primarily for direct-to-home TV broadcast services – with a coverage zone including the entire Indian subcontinent. 

Additionally, GSAT-8 carries the two-channel GAGAN system for aircraft navigation assistance over Indian airspace and adjoining areas.

GSAT-8 – which also is known by the INSAT-4G designation – designed for a mission life of 12 years. Operating with a payload power of 5,300 Watts, the satellite will be located at an orbital position of 55 deg. East longitude following its deployment by Ariane 5.

The GSAT-8 platform will be launched along with ST-2, a spacecraft for the ST-2 Satellite Ventures Pte Ltd. joint venture of Singapore Telecommunications Ltd (SingTel) and Chunghwa Telecom Company Ltd.

In total, 13 Indian satellites have been lofted by Ariane launchers, beginning with APPLE in 1981, and followed by INSAT-1C in 1988, INSAT-2A in 1992, INSAT-2B in 1993, INSAT-2C in 1995, INSAT-2D in 1997, INSAT-2E in 1999, INSAT-3B in 2000, INSAT-3C in 2002, INSAT-3E and INSAT-3A in 2003, INSAT-4A in 2005 and INSAT-4B in 2007.

Another satellite operated by India was INSAT-2DT, which originally was orbited by Ariane in 1992 as Arabsat-1C and acquired by ISRO in November 1997.

Arianespace are targeting six Ariane 5 missions in 2011, along with the first two launches of the medium-lift Soyuz and the lightweight Vega’s maiden flight – all from the Spaceport in French Guiana; as well as three Soyuz missions from Baikonur Cosmodrome in Kazakhstan.

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Ariane 5 ECA Launch:

Originally scheduled for liftoff on March 30, this dual-payload mission was delayed following an interruption of the final countdown when an incorrect displacement of one of the Vulcain 2 engine’s actuators was detected. The Ariane 5 was transferred back to the Spaceport’s Final Assembly Building on April 1, where the actuator was replaced and the launch vehicle was returned to its flight configuration.

Following a successful review, Ariane 5 was cleared for rollout from the Final Assembly Building to the ELA-3 launch zone, where it will be readied for liftoff on Friday during a launch window that opens at 6:37 p.m. local time in French Guiana and continues to 7:41 p.m.

The Ariane reached its 200 flight milestone via the launch of the Automated Transfer Vehicle (ATV-2) – the opening launch of the year, via the Ariane 5 ES launcher – with the cargo vehicle currently docked to the International Space Station (ISS).

The Ariane 5 ECA (Cryogenic Evolution type A) – the most powerful version in the Ariane 5 range – is being used for this flight. 

The Ariane 5 ECA is an improved Ariane 5 Generic launcher. Although it has the same general architecture, a number of major changes were made to the basic structure of the Ariane 5 Generic version to increase thrust and enable it to carry heavier payloads into orbit.

Designed to place payloads weighing up to 9.6 tonnes into GTO, this increased capacity allows the Ariane 5 ECA to handle dual launches of very large satellites.

During the initial countdown on March 30, all was green through to main engine ingition, with the Vulcain main engine igniting and ramping up to full power – as designed.

However, instead of the twin solid rocket boosters then firing to launch the vehicle, some seven seconds later, the vehicle remained on the pad, with the main engine still firing for what appears to be at least another ten seconds.

With the vehicle in a pad abort stance, safing was undertaken, with both the vehicle and its passengers secured.

The launch was delayed to April 22, due to the need to rollback the vehicle to its integration center for investigations and reconfiguration – given the umbilicals were all released during the pad abort.

Overview:

The 57th launch of an Ariane 5 – designated as VA201 – will carry a total lift performance of nearly 10,065 kg, which includes the combined 8,965 kg liftoff mass of the two spacecraft passengers, along with the SYLDA dual payload dispenser and integration hardware.

With a liftoff mass of 6,000 kg, the Yahsat Y1A spacecraft is based on Astrium’s Eurostar E3000 platform.

Yahsat Y1A is the initial telecommunications relay spacecraft for Al Yah Satellite Communications Company (Yahsat), and it was built by an industrial team of EADS Astrium and Thales Alenia Space – which have the responsibility of co-prime contractors.

Astrium is the lead for a turnkey delivery of the two-satellite Yahsat system, while Thales Alenia Space is in charge of the launcher procurement.

With a payload of Ku-, Ka- and C-band transponders, the spacecraft will provide coverage over the Middle East, Africa, Europe and Southwest Asia.

Intelsat New Dawn is the first-ever African private sector communications satellite, with the mission of supplying critical communications infrastructure for African customers.  To be marketed and operated as part of the Intelsat satellite fleet, Intelsat New Dawn will deliver wireless backhaul, broadband and media content – which are the fastest growing satellite-based applications in Africa.

Produced by Orbital Sciences Corporation in Dulles, Virginia, the relay platform carries C-band and Ku-band transponders, and will have a liftoff mass of 3,000 kg.  After its deployment by Ariane 5, it will be positioned at a geostationary orbital slot at 32.8 degrees East for its Africa area coverage.

The latest Ariane flight will keep up the mission pace for Arianespace during the year, in which the company is targeting a total of 12 launches – composed of six Ariane 5 flights, the first two Soyuz launches and Vega’s inaugural liftoff, all from the Spaceport; along with three Soyuz launches from Baikonur Cosmodrome in Kazakhstan.

At the Spaceport, another Ariane 5 mission is also taking shape for a May mission with the ST-2 and GSAT-8 satellites – with initial assembly completed. The Spaceport is designed for such parallel mission operations, enabling two Ariane 5s to be prepared for flight.

(Images – Via Arianespace).

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ATV-2 Docking Sequence:

In preparation for the docking manoeuvre, ATV-2 controllers commanded spacecraft’s thrusters into a programmed firing sequence to move the spacecraft from its initial phasing orbit into a “transfer to vicinity of ISS” orbit. This was then followed by an integration of the phasing and rendezvous portions of the orbital approach timelines.

These manoeuvres will, in turn, bring ATV-2 to within 30 kilometers of the ISS, at which point direct Space-to-Space comm coverage will begin, and the ISS crew will be able to monitor ATV-2′s systems. At this time, the rendezvous phase of ATV-2′s approach will commence, with rendezvous taking place along the V-bar (Velocity bar).

At a distance of 4.5km, RGPS (Relative Global Positioning System) navigation will begin, taking over from AGPS (Absolute GPS) navigation. RGPS detects ATV’s position in space using sensors on the ATV’s and station’s exterior, as opposed to AGPS which uses GPS satellites for navigation.

New rendezvous equipment will be used during the rendezvous and docking sequence – the Proximity Communication Equipment (PCE). PCE was installed in the SM last October, as was successfully checked out in order to ensure proper functionality. The PCE is designed to transmit signals between the WAL3 and WAS2 antennas in the SM, which receive data from the ATV, and ground stations on Earth.

The ISS crew will begin taking official distance measurements on ATV-2 once the vehicle passes inside the 20 meter mark. At 1 meter distance, the ISS crew will go “hands off” and let the ATV-2 perform its final docking sequence.

This final docking sequence will include four steps: contact/capture by Probe Head and Latches, Docking start/Probe retraction by the Probe and Docking Mechanism (at which point interface alignment will be verified), ATV hooks closure (at which time the interface seal will be confirmed), and ISS hooks closure.

During the rendezvous and docking sequence, that Stations’ solar arrays will be placed into a new configuration to protect for RGPS multipathing.

As noted by the MOD FRR (Mission Operations Directorate Flight Readiness Review), available for download on L2, “New configuration [will] allow Fwd BGAs  (Beta Gimbal Assemblies) to be positioned at their best power generating angles, or even remain in autotrack, while the aft BGAs [will be] constrained for loads/erosion”.

Longeron shadowing concerns on ATV-2 will also be mitigated during rendezvous and docking ops.

Previous In-Flight Anomalies and Lessons Learned from ATV-1:

In all, the European Space Agency’s (ESA’s) flight of ATV-1 in 2008 was remarkably clean, with the MOD FRR only noting one IFA (In-Flight Anomaly): Structural Dynamic Measurement System Late Record Stop Command.

As the MOD FRR document relates, “During Structural Dynamic Measurement System (SDMS) operations to record accelerometer/strain gauge data during ATV-1 Docking, the command to stop recording data was not sent in time to prevent overwrite of the 632 second memory buffer.”

This led to the overwrite of the first two (2) minutes of SDMS sensor data, including information on initial contact. To prevent this problem from occurring again, the OSO has scheduled dedicated personnel to perform SDMS operations during “high intensity times.”

Additionally, several lessons learned from ATV-1′s mission were initially planned for implementation during ATV-2 but have since been deferred to ATV-3 and subsequent ATV flights in the interest of time and resources.

One such lesson resulted in the request by the ATV Control Center for more responsibilities in ATV crew time planning. As it currently stands, the ATV is considered a USOS vehicle and, as such, the USOS is responsible for planning all ATV activities.

Under the agreement to defer most ATV Control Center planning to ATV-3+, including the planning of all ATV crew tasks not covered by cargo and docking/undocking operations, some planning activities are being phased in during ATV-2.

These include the planning of all waste, urine, and/or condensate transfers by MCC Moscow. All waste, urine, and/or condensate transfer planning and control activities for ATV-3+ are open for discussion.

However, two lessons learned from ATV-1 have already been implemented for ATV-2.

During ATV-1, the requirement to perform bladder integrity testing prior to loading the empty ATV was a constraint that was not documented in any flight rule. For ATV-2, the requirement has been included in the Flight Rules.

Likewise, during ATV-1, crew time was allotted weekly to manage the Center of Gravity (CG) of the spacecraft; however, CG adjustments were only performed once over the entire docked mission since propellant is the major contributor to CG with cargo second.

For ATV-2, clearly defined CG limits and uncertainties have been defined (which allows for uncertainties in mass distribution), as have minimum undock mass limits.

ESA will monitor ATV-2′s CG and “notify ATV ISO when approaching CG limit. If CG adjustment needed, ATV ISO will put the task on the crew’s to do list.”

Another anomaly that was seen during ATV-1 related to Multi Layer Insulation (MLI) coverings on the exterior of the ATV. MLI serves to prevent the pressure shell of the ATV from becoming too hot or cold in the vacuum of space.

Click here for ISS news articles: http://www.nasaspaceflight.com/tag/iss/

During the ATV-1 launch in April 2008, trapped air underneath the MLI rapidly expanded once the vehicle reached the upper atmosphere. The result was a “ballooning” effect on the MLI, as the trapped air beneath the MLI ripped it from its attachment points as it escaped into the lower air pressure of the upper atmosphere.

Erroneous readings where seen on ATV-1′s temperature sensors, which gave ground control teams a good idea of what had occurred. The theory was confirmed once ATV-1 rendezvoused with the ISS, with its MLI visibly protruding in places.

Although the temperatures of ATV-1 were never an issue and the loose MLI was deemed to be not a serious failure, ATV-2 teams worked hard to ensure that the same incident doesn’t occur on ATV-2.  An upgraded MLI was developed with increased numbers of holes for air ventilation – which will allow the air to escape without having to push the MLI aside.

The number of MLI attachment points was also increased, and the way the MLI blankets overlap each other was improved. The new designs underwent rigorous testing in a vacuum chamber. LINK BLOG

ATV-2 Payload:

The ATV’s pressurised cargo is carried inside the Integrated Cargo Carrier (ICC), which contains two types of cargo – dry and fluid.

Dry cargo is contained in the pressurised segment of the ICC, which accounts for 90% of the volume of the ICC. The dry cargo area is capable of launching eight space station racks. However, the hatch on the Russian probe and drogue docking system, which the ATV uses, is not large enough to facilitate the transfer of racks. Therefore, only rack-sized frames are installed in the ATV, which are used to house Cargo Transfer Bags (CTBs).

Fluid cargo is contained in the unpressurised segment of the ICC, which accounts for 10% of the volume of the ICC. ATV-2′s fluid cargo will not include any water, as enough water already exists on board the ISS. However, ATV-2 will carry 220 pounds of oxygen for the station. ATV-2′s ICC has an increased cargo capacity than it did on the ATV-1 mission, due to the use of lighter weight racks, and modifications that have been made to the Ariane V booster.

In total, the ATV-2 mission will carry 1,600kg of dry cargo to the ISS. None of this cargo will be unloaded until Expedition 27 begins in March, due to the fact that the PMM being launched on STS-133 will not be ready to accept cargo until this time. As soon as a CTB is removed from ATV-2, a piece of trash will be loaded in its place, meaning that ATV-2 will slowly fill up with trash over the course of a few months.

Although ATV can carry eight (8) racks in total, ATV-2 will only carry six (6). Once docked to the ISS, two soft racks made from fabric will be assembled in the two (2) empty racks bays, in order to provide the ISS crew with some temporary stowage space. The reason for the decreased amount of dry cargo is because ATV-2 is carrying an increased amount of wet cargo.

Wet cargo is contained in the ATV’s Service Module (SM), which houses all propellant tanks, avionics and electrical power systems.

Two types of propellants are contained in the SM – propulsive support propellant, which is used for ATV rendezvous burns and ISS reboosts, and refuelling propellant, which is transferred to the ISS’s fuel tanks. The SM can contain up to 4 tonnes of propulsive support propellant, and up to 860kg of refuelling propellant. ATV-2 will carry slightly less propulsive support propellant than ATV-1 did, due to the fact that ATV-2 will not perform any demonstration manoeuvres.

ATV-2 ISS Reboost Plan:

ATV-2 will reboost the ISS’s orbit by a massive 40km, and will hold the world record for the largest reboost ever performed over the shortest amount of time.

The ATV is the only vehicle with enough propulsive might to perform such a massive reboost – Russia’s Progress vehicles do not possess enough propellant to perform the reboost on a single flight. In order to perform the 40km reboost, nearly 10,000 pounds of propellants will be consumed by ATV.

The purpose of such a massive reboost is to set the ISS up for operations in the post-Shuttle era. From the ISS’s launch in 1998 until now, it has operated at an altitude of approximately 250km, in order to allow Space Shuttles to visit carrying the maximum amount of payload. This is because, if the ISS orbits at a lower altitude, then vehicles need less propellant to reach the ISS – meaning that more payload can be carried.

However, operating the ISS in a lower orbit increases drag on the complex due to increased amounts of atmospheric particles hitting the station’s exterior. Operating at a lower altitude also makes the station more susceptible to solar activity, which increases Earth’s atmospheric pressure, which further increases drag on the station. Over time, this drag causes the ISS’s orbit to lower – meaning that the station has to be periodically reboosted, which requires propellant.

Raising the ISS’s orbit by 40km will result in less drag being placed on the complex, meaning fewer reboosts will be required. Due to the decreased requirement for reboosts, VVs will be able to carry less propellant to the ISS. At its current altitude of 250km, the ISS requires around 19,000 pounds of propellant a year for reboosts. In its new, raised orbit (290km), it is estimated that the ISS will only require 8,000 pounds of propellant a year for reboosts.

The decreased requirement for propellant in VVs will be slightly offset by the fact that VVs will also be able to deliver less dry cargo to the ISS, due to its higher orbit. This means that the upmass gained by carrying less propellant won’t translate into an equal increase in dry cargo upmass.

ATV-2 is currently scheduled to undock from the station on 4th June. However, an extension to the ATV-2 mission is currently being considered by ESA in order to ensure that all of ATV’s propellants will be consumed.

It is not yet known whether the ATV-2 mission will be extended to its maximum duration of six months, in order to allow the 40km reboost to be performed after the STS-135 mission currently scheduled for June. Doing so would allow STS-135 to gain the maximum upmass by rendezvousing with the ISS in its lower orbit.

On Friday 25th February, the day following the ATV-2 docking and the day prior to the planned STS-133 docking, a test reboost of the ISS will be performed by ATV-2. The reboost is scheduled to begin at 10:33 AM GMT, with a Delta V of 0.5 meters per second.

(Images via ESA and L2 ATV documentation). For other ATV-2 content, visit the excellent ATV-2 blog by ESA: http://blogs.esa.int/atv

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Mission Configuration, Overview, and Priorities:

The resupply vehicle - named after famous German astronomer and mathematician Johannes Kepler - was delayed after a red in the countdown at around T-4 minutes on Tuesday. Given the lack of a launch windown, the Ariane 5 was placed into a 24 hour scrub turnaround. Now ATV-2 has launched on Wednesday, STS-133 may move to February 25. However, discussions are continuing within NASA to evaluate the actual launch date.

The launch – at the second attempt – from the Guiana Space Centre in Kourou, French Guiana in South America, will aim to place ATV-2 into a 51.6 degree inclination orbit for an eight (8) day chase with the International Space Station. During the initial eight days in orbit, ATV-2 will perform several phasing burns to properly align its trajectory with that of the Space Station’s.

Originally, ATV-2′s launch schedule was created with 3-days of launch contingency (on orbit loiter capability) dubbed a “scrub window” to preserve a February 26th docking to the international outpost.  

However, delays to the STS-133/Discovery mission into late-February prompted NASA and ESA to reevaluate this 3-day scrub window.

As a result, the 3-day launch contingency time was removed from ATV-2′s launch profile, thus leaving no launch delay contingency time between liftoff and the mandatory 8-day phasing period leading up to docking with the Station.

In turn, this will mean a day-for-day slip to ATV-2′s docking day for every day the launch is scrubbed/postponed. This will also translate into a day-for-day slip to Shuttle Discovery’s launch date since ATV-2 must be docked to the ISS prior to Discovery’s launch.

In all, unlike ATV-1 in 2008, ATV-2′s mission will have no on-orbit demo days and will proceed directly to docking with the Space Station at an altitude between 350-380km.

According to the ATV-2 NASA MOD FRR (Mission Operations Directorate Flight Readiness Review, Dec. 2010) presentations – full set available on L2 –  no ISS crew sleep shifting will be required for ATV-2 rendezvous and docking.

The December document, which protected for a potential launch of Discovery’s 133/ULF5 mission in late-February, further states that minimal ISS crew sleep shifting would be required following ATV-2′s docking to the Russian Zvezda Service Module and Discovery’s docking to PMA-2 on the direct opposite side of the ISS.

In all, ATV-2 will weigh ~20 metric tons at launch, carry 4000kg of ISS propellant, 860kg of refuel propellant, 102kg of gas, 0kg of water, and 1638kg of dry cargo for the International Space Station for a grand total of ~6600kg.

While the planned docked period is only scheduled to last ~96days, ATV-2 could remain docked to the ISS for nearly 180days. In fact, the 96-day docked mission is currently classed an Under Review and will be evaluated as the mission progresses.

Furthermore, like all spaceflight missions, the flight of ATV-2 carries several Mission Priorities, including: “perform ATV PCE (Proximity Communication Equipment) to Ground signal testing, dock ATV-2 to SM (Service Module) aft port, remove and stow ATV Control Panel and ATV PCE in SM, and perform ATV ingress operations and cargo transfers including Crew Supplies, Utilization, Vehicle Hardware, Portable Computer System, and EVA equipment.”

One hundred kilograms of gas will also be transferred to the Station before the ISS crew begins packing the vehicle for its destructive return to Earth.

Prior to ATV-2 undocking, the ISS crew will remove all items identified as re-useable (smoke detectors, for example) before “[installing and activating] one sensor suite inside ATV-2 for Reentry Breakup Recorder Payload and [installing and testing] ATV control panel and PCE in the SM prior to undock.”

New Operations and Network Support:

Perhaps one of the more noticeable new ops during ATV-2′s mission will be the lack of on-orbit demonstration days.

During the premiere ATV mission in 2008, two (2) demonstration days were held to validate ATV’s overall ability to perform automated rendezvous and docking ops with the Russian portion of the Station.

These demo days were largely a result of a trilateral agreement between NASA, Roscosmos (the Russian Federal Space Agency), and ESA to “demonstrate safety-critical ATV functions on-orbit the first time before they are needed for safety and to actively reduce risk.”

Thus, these demo days were not considered to be in-flight vehicle qualifications and were not mandatory to meet NASA Safety Requirements since those requirements were met prior to launch.

As such, these demos will not be repeated on ATV-2′s flight since the vehicle is of the same design as ATV-1.

Moreover, ATV-2 will be used (as numerous second vehicle flights are) to prove software and hardware capability and ops concepts.

ATV-2, like its predecessor, will have two TDRS (Tracking and Data Relay Satellite) transponders. But unlike its predecessor, ATV-2 will carry extensively redesigned software to allow two-way communication between itself and ESA ground stations via the prox link.

This new capability provides additional redundancy during prox ops – especially during the rendezvous phase. As stated in the MOD FRR Flight Director Overview presentation, available for download on L2, “If 1 TDRS chain fails prior to S-1/2, escape to parking, check out prox link with ground stations, re-rendezvous with IMMT approval” would be allowed.

Similarly, “If 1 TDRS chain fails after S-1/2, continue to dock, configure software for possible loss of second chain, and prepare plan for undock” would be initiated.

Should the second TDRS chain fail past the S-1/2 point, either ATV-2 itself or the ISS crew would initiate an ATV-2 escape procedure from ISS and the vehicle (ATV-2) would then be prepped for reentry.

This necessary and critical use of the TDRS network is in large part one of the driving reasons why ATV-2 must be docked to the ISS prior to the launch of Shuttle Discovery/STS-133. Since the TDRS network is limited in its comm load capability, and the ISS and Shuttle (both manned vehicles) take priority on the TDRS network, ATV-2′s use of the TDRS network will automatically be limited to the nearly non-existence range once Discovery launches.

Since Discovery will not launch until after ATV-2′s docking to the Station, ATV-2 will have plenty of comm satellite and ground tracking/comm station availability/use during its launch, orbital insertion, and phasing periods.

In all, three (3) C-band radar passes will be available to support ATV-2 during the launch and post-insertion phases of the flight. The Jonathan Dickenson station will be available during orbit 2 ops, as will the MILA tracking station at Cape Canaveral, FL and Wallops station in Virginia.

In addition to these C-band radar tracking stations, continuous S-band Single Access (SSA) coverage will be available during the Launch & Early Orbit Phase (LEOP). Multiple Access (MA) Forward/Return Continuous and SSA coverage for 20 minutes on each orbit will also be available to support routine phasing operations. Should more comm time become a requirement, ATV-2 could utilize “TDRSS Unused Time” (TUT).

One SSA 20 minute comm coverage period will be required every 5 orbits.
 
As noted by the Network MOD FRR presentation, “In the event of a contingency, all available C-band radars [will] be brought up for support.”

In all, ATV-2 will use four TDRS satellites: TDS, TD171 (for SSA coverage), TDW (for MA coverage), and TDZ. Critical support will be carried through SSA and non-critical ops through MA and available SSA.

Moreover, some of the same TDRS issues the JAXA (Japan Aerospace Exploration Agency) team prepared for during the ramp up to the HTV-2 launch last month, will be covered by the ATV-2 control team as well.

As noted by the Network presentation, “TDS Power System: Battery 1 failed. No battery issues during last eclipse season (07/24/10 – 09/25/10). Next eclipse season 01/21/11 – 03/23/11.”

The TDS (TDRS-4) is also experiencing downlink telemetry errors (hits) which are irregular and random.  As with HTV-2, a spare Traveling Wave Tube Amplifier (TWTA) is available should these downlink errors occur.

Furthermore, all SSA events will be scheduled on the SA1 antenna only of TDRS-275. No restrictions exist for MA ops and full utilization of the Eastern and Western TDRS satellites exists for these ops.

Thus, the scheduled time on TDRS-275 will be minimized and the SA1 antenna used only for docking and undocking with handover to TD-171 as early as possible. Lastly, all times of use for TDRS-275 must be preapproved by the NASA Network Director.

(Images: Lead – ESA. Within the article – via L2 ATV-2 Presentations).

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