ATV-3 launch slipped to late March 23 due to cargo issue

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ESA are set to announce a new launch date for ATV-3’s launch to the International Space Station (ISS) –  now confirmed to be March 23 – after it was determined engineers will have to gain access to the spacecraft to reconnect a loose strap which has become disconnected from its internal cargo. ATV-3 was scheduled to launch atop of the Ariane 5 launch vehicle on March 9.

ATV-3:

ESA’s third Automated Transfer Vehicle (ATV), Edoardo Amaldi will be launched from Europe’s Spaceport in Kourou, French Guiana via Arianespace’s workhorse Ariane 5, follow up two successful missions to provide the ISS with vital supplies.

The launch was scheduled for March 9, which would have resulted in its arrival at the ISS for a docking to the Service Module (AM) Aft port ten days later on March 19. It was then scheduled to undock from the ISS on 27th August, before before reentering the atmosphere and deliberately burning up together with several tons of Station waste.

Based on a launch date of March 23 – pending the official announcement from ESA – sources note docking would be advanced on the flight profile to around March 28.

The launch date slip was announced by ESA on Friday morning. However, the information only cited the problem was found during recent inspections relating to preparations for the Launch Readiness Review (LRR). ATV-3 was recently mated to the Ariane 5 as part of the integration flow.

“A routine inspection has concluded that additional measures are required to ensure the maximum readiness of the third Automated Transfer Vehicle for launch. It has therefore been decided to postpone the launch previously scheduled for 9 March,” noted ESA.

“A new launch date will be announced as soon as possible. The launch of ESA’s third Automated Transfer Vehicle (ATV-3) is part of the internationally coordinated servicing effort to support the International Space Station.”

ESA later only confirmed the new launch date.

Sources claim that the inspections found one of the straps inside the ATV-3 was found to be loose. This will require engineers to gain access to the inners of the spacecraft to reconnect the strap to an element of cargo it has been tasked with keeping secure during the launch and flight to the ISS.

ATV-3 will carry more “dry” cargo (i.e. internal items) than ATV-2 carried to the station in 2011, due to modifications that have been made that will allow ATV to carry additional internal payload.

This will mean that less “wet” cargo (i.e. propellants) will be carried by ATV-3, however this will not be of big impact to the ISS since ATV-2 performed four “big boosts” of the ISS in 2011 that boosted the station’s altitude to a mean of around 400km, meaning less reboosts will be needed in future, and thus less requirements for propellants. (L2 Link).

ATV-2 weighed in at ~20 metric tons at launch, carrying 4535kg of ISS propellant, 851kg of refuel propellant, 100kg of gas, and 1114kg of dry cargo for the International Space Station for a grand total of ~6600kg.

In total, ATV-3 will carry a fuel load estimated at 6271 kg.

Dry cargo is contained in the pressurised segment of the Integrated Cargo Carrier (ICC), which accounts for the vast majority of the volume of the ICC. The dry cargo area is capable of launching eight space station racks.

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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). It is possible the loose strap is related to one of the CTBs.

In total, ATV-3 will carry a fuel load estimated at 6,060 kg. Approximately 2,200 kg will be used up by the ATV during the spacecraft’s journey to the ISS, and for the post-mission de-orbiting.

Around 3,000 kg will be consumed in attitude control and re-boost maneuvers while the ATV is mated to the orbital outpost, while the remaining 860 kg is destined for transfer from the ATV to the station’s Russian portion.

ATV-3 is the first spacecraft of its range to have been processed and launched within the target rate of one per year. This marks the start of ATV as an annual production-line supply vehicle for the Space Station, positioning Europe as an essential partner in operating the orbital outpost.

The next ATVs, Albert Einstein and Georges Lemaitre, will follow in 2013 and 2014.

A full outline article will be published on Tuesday.

(Images: ESA and Arianespace)

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