The European Automated Transfer Vehicle-3 (ATV-3) spacecraft, also known as “Edoardo Amaldi”, has successfully concluded it’s near 6.5 month resupply and servicing mission to the International Space Station (ISS) after making a fiery plunge through Earth’s atmosphere for a destructive re-entry over a remote swath of the Pacific Ocean, where any surviving debris safely splashed down a short time later.
ATV-3 background:
ATV-3 was the third of Europe’s now well proven ISS resupply vessels, following the flight of ATV-1 “Jules Verne” in 2008 and ATV-2 “Johannes Kepler” in 2011.
Built as part of Europe’s contribution to the ISS, the ATVs serve to transport pressurised and unpressurised cargo to the ISS.
Following the retirement of the Space Shuttle last year, ATVs are now the vehicles capable of delivering the single largest cargo load to the ISS, with a cargo delivery capacity of around 7,500kg, including crew provisions, scientific material, water, oxygen, air, and propellant both for ISS refuelling and ISS reboosts.
ATV-3 was launched atop an Ariane V booster from the Kourou space center in French Guiana on 23 March 2012, and docked to the ISS at the Service Module (SM) “Zvezda” Aft port two days later on 28 March.
Following hatch opening, it was decided that extra air scrubbing equipment was needed inside ATV-3 due to the fact that ATV-3’s hatch had been opened soon before launch to correct an issue with a loose strap.
This late access prevented ATV-3 from being “flushed” with clean air prior to launch, and so the extra scrubbing equipment was needed to ensure that no potentially harmful microbes from Earth were present inside the ATV-3 during flight. However, once the Russian POTOK air purifier was plugged in inside ATV-3, the Russian Equipment Control System (RECS) power channel 1 inside ATV-3 was unexpectedly lost.
Troubleshooting was unable to bring RECS channel 1 back online, and so for the remainder of ATV-3’s mission the spacecraft had been operating on the back-up RECS channel 2, which still allowed for full power capability inside ATV-3.
There were also a few other minor issues seen during the flight of ATV-3, including failed cabin fans, aborted reboost burns, and reboost burns performed using the incorrect engines, however the diligent ATV engineering teams were able to successfully work through these problems and ensure a full and successful mission for ATV-3.
The total cargo transferred from ATV-3 to the ISS during the six months of Attached Phase Operations (APO) included 2200kg of dry cargo, 284kg of water, 66kg of oxygen, and 33kg of air.
In addition, ATV-3 transferred 820kg of propellant to the ISS’ tanks, and also performed nine ISS reboosts totalling 3400kg of expended propellant.
In place of the transferred dry cargo, 989kg of dry trash was loaded, and in place of the wet cargo, 350kg of urine and other waste liquid was loaded, all of which burnt up in the atmosphere along with the ATV-3 spacecraft.
ATV-3 End Of Mission (EOM):
Following an undocking from the SM Aft port on Friday (28 September), which was delayed from 25 September due at first to a communications issue between ATV-3 and the ISS, and then a Debris Avoidance Maneuver (DAM) burn which was ultimately cancelled, ATV-3 has been free flying from the ISS for the past five days.
In preparation for ATV-3’s impending demise, the first de-orbit maneuver, called DEO-1, was performed at 9:42 PM GMT on 2 October, and lasted for nearly 14 minutes.
The second de-orbit maneuver, DEO-2, was then performed at 12:42 AM GMT on 3 October , and lasted for 15 minutes.
Following initiation of a tumble, ATV-3 then gradually began to feel the increasing effects of Earth’s atmosphere, as temperatures rose, first ripping off the four X-shaped solar arrays, and then eventually rupturing the pressure vessel and propellant tanks, leading to vehicle disintegration.
Any surviving debris from re-entry impacted the Pacific Ocean at around 1:30 AM GMT on 3 October, thus concluding the highly successful ATV-3 mission.
Aboard the ATV-3 during re-entry was the Re Entry Breakup Recorder (REBR), a spacecraft “black box” designed to gather data on vehicle disintegration during re-entry in order to improve future spacecraft re-entry models.
A REBR successfully took data during the re-entries of the Japanese HTV-2 and HTV-3 missions in 2011 and 2012, respectively, however the REBR aboard the ATV-2 spacecraft during its re-entry in 2011 failed to take any data.
This was suspected to be related to the fact that the ATV-2 REBR was bolted to the ATV structure itself, as opposed to being strapped down as it was on HTV-2. Plus, the large propellant tanks on the ATV may have exploded, damaging the REBR.
To mitigate this, the ATV-3 REBR was located further forward of the propellant tanks and secured only with straps, which appears to have worked since it has been confirmed that the ATV-3 REBR did successfully take data during re-entry.
Future ISS resupply vehicles:
Hot on the heels of ATV-3’s departure from the ISS will be the arrival of SpaceX’s Dragon spacecraft on the first Commercial Resupply Services (CRS) mission.
The CRS-1 (SpX-1) Dragon, which has now been mated to its Falcon 9 rocket, is expected to launch on 8 October at 12:35 AM GMT, with a berthing to the ISS coming roughly two days later on 10 October. Unberthing, re-entry and splashdown are then targeted for 28 October.
The next ATV mission, ATV-4 “Albert Einstein”, is also deep in processing, with the spacecraft now arrived the Kourou space center in French Guiana. Launch is currently targeted for 17 April 2013.
The fifth ATV mission, ATV-5 “Georges Lemaitre”, is targeted to launch roughly one year after that, in April 2014, which will be the final mission of the ATV program.
(Images: L2’s ISS and ATV sections, plus NASA).
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