Europe’s ATV heavy hauler launches on penultimate trip to ISS
The European Space Agency’s (ESA’s) Automated Transfer Vehicle-4 (ATV-4) spacecraft launched toward the International Space Station (ISS) on Wednesday at 9:52:11 PM GMT, atop an Ariane V booster from the Kourou Space Center in French Guyana. ATV-4 is the heaviest spacecraft ever launched by Europe, and marks the largest ever load of internal ISS cargo to be transported by an ATV vessel.
The ATV – Europe’s ISS heavy hauler:
Since the retirement of the Space Shuttle fleet in 2011, the ATV is the largest cargo delivery vehicle in the ISS program’s arsenal, which is not only able to transport a large amount of internal, or “dry” cargo to the ISS, but is also able to haul a large load of propellants, gases, and water, or “wet” cargo to the station.
ATV-4 in particular – named after famed physicist “Albert Einstein” – will be hauling the largest ever load of dry cargo to the ISS for the ATV program, following the three previous ATV flights in March 2008, February 2011, and March 2012.
ATV-4’s internal cargo load, located inside the Integrated Cargo Carrier (ICC) portion of the vehicle, will total in at 2,479kg of resupply items, spare parts, crew provisions, and scientific materials.
ATV-3 in 2012 carried only 2,200kg of internal cargo, while ATV-2 in 2011 carried 1,605kg, and ATV-1 in 2008 carried 1,150kg.
As well as carrying eight integrated cargo racks (the first two ATVs carried only six), ATV-4 will also be configured to carry additional large cargo bags on the rack fronts of the Aft-Nadir and Aft-Zenith racks, in addition to the usual bags on the Aft-Port and Aft-Starboard rack fronts.
In addition to that, brand new Late Cargo Access Means (LCAM) equipment at the Kourou Space Center has allowed ground teams to load much more “late load” cargo than ever before, with the new equipment allowing for bags weighing up to 75kg to be loaded, whereas the previous LCAM equipment allowed bags of only 25kg to be loaded.
This new LCAM equipment, coupled with the additional location for large cargo bags on the Aft-Zenith and Aft-Nadir rack fronts, has allowed an extra 218kg of late load cargo to be carried on ATV-4, with the total amount of late load cargo on ATV-4 being 1,109kg, whereas ATV-3 carried only 592kg, ATV-2 carrying 435kg, and no late load cargo at all for ATV-1.
Cargo items of note flying on ATV-4 include a large 80kg water pump for Europe’s Columbus module, a Fluids Control and Pump Assembly (FCPA) for the Urine Processor Assembly (UPA), one of which was flown on ATV-3 last year prior to a failure on ISS causing another spare to need to be flown, a GPS antenna for the Japanese Experiment Module (JEM), and a 3D printed toolbox to be used to stow tools needed in the Columbus module.
As for fluid, or wet cargo, which is located in the Service Module (SM) portion of the vehicle, ATV-4 will carry 2,235kg of propellant for the ATV’s vessel itself, 2,580kg of propellant for ISS reboosts, 860kg of propellant to re-fuel the Russian Segment (RS) of the ISS, 100kg of gasses, and 565kg of water.
Altogether, ATV-4 will carry 4,105kg of wet cargo, which is actually less than ATVs 3 and 2, which carried 4,395kg and 5,488kg of wet cargo, respectively. This means that, despite the fact that ATV-4 will carry the largest ever load of dry cargo, the lesser amount of wet cargo means that ATV-4 will carry less cargo in total than its predecessors, with ATV-4 weighing in at 6,584kg in total, whereas ATV-3 was 6,595kg, ATV-2 was 7,093kg, and ATV-1 was 4,557kg.
Rendezvous and docking:
Following ATV-4’s launch, which with a total vehicle lift-off mass of 20,235kg will be the heaviest spacecraft ever launched by Europe, the vehicle began its ten day rendezvous with the ISS.
Prior to that however, a new 3D stereo camera system recorded the spacecraft’s separation from the Ariane V upper stage, in order to offer new perspectives in understanding separation events.
Following that, ATV-4’s four X-shaped solar arrays will need to be deployed, as will the proximity communications boom, which will be a particular item of interest on this mission since the boom deploy signal was not received until 141 minutes after its planned deployment on ATV-2, and 46 hours after its planned deployment on ATV-3.
As detailed in a previous NASASpaceflight.com article on ATV-4, some Multi Layer Insulation (MLI) changes have been made to the ATV-4 prox boom to eliminate any possible MLI “ballooning” effects during launch.
Before ATV-4 can dock to the ISS at the Service Module (SM) Aft port, the vehicle which is currently occupying it (Progress M-19M) must be undocked on June 11, which will be another item of interest for the ATV-4 mission since the cameras on Progress M-19M during its undocking will provide the first views of the possibly damaged Laser Retro Reflector (LRR) used by the ATV during docking.
The concern is that one of the LRRs (out of three in total) may have been damaged by an undeployed Kurs antenna on Progress M-19M during its docking on 26 April, which was, sources indicate, conducted by the Russians without the approval of the station’s International Mission Management Team (IMMT).
The LRR is not the same as the Videometer that was replaced on SM Aft during Russian EVA-32 on 19 April.
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If the LRR is found to be damaged, ATV-4 may be required to wait while a Russian spacewalk is performed to R&R the LRR unit with a new one recently flown up on Soyuz TMA-09M. Assuming the LRR is undamaged however, ATV-4 will dock to the SM Aft port ten days after launch on 15 June.
ATV-4 mission outlook:
Following docking and hatch opening, ATV-4 will “settle in” to the ISS for a long period of “Attached Phase Operations”.
This period will include cargo unloading, trash loading, and propulsive support for the ISS, including attitude control maneuvers, reboosts, and Debris Avoidance Maneuvers (DAMs).
ATV-4 is currently planned to undock from the ISS on 28 October, whereupon it will conduct a de-orbit burn for a destructive re-entry into Earth’s atmosphere, thereby concluding the penultimate mission for ESA’s ATV program, with only one launch then left to be conducted – ATV-5 “George Lemaitre” in June 2015.
While that flight will be the final mission for the ATV program, its legacy will live on in the form of the Service Module (SM) for the Multi Purpose Crew Vehicle (MPCV) Orion, which will be constructed by ESA based heavily on the ATV SM design.
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