Russia’s Progress M-15M spacecraft, designated by NASA as 47P, has successfully re-docked to the International Space Station (ISS) for the second time, following its undocking one week ago. The re-docking results in the successful demonstration of the new Kurs-NA automatic rendezvous system, to be used on future Progress and Soyuz spacecraft.
After spending three months docked to the ISS, during which time the Progress was emptied of cargo and filled with trash, Progress M-15M undocked from the ISS last Sunday (22 July) in order to conduct a test of a new Kurs system.
Kurs is the system used by Progresses for automated rendezvous and docking with the ISS, with the current version of the well-proven system being Kurs-A. However, in addition to its Kurs-A antennas, Progress M-15M was also fitted with a new antenna system known as Kurs-NA.
While the original Progress M-15M docking to the ISS on April 22 used the traditional Kurs-A, in order to ensure that the Progress’ cargo would not be wasted should the new Kurs-NA system fail, the second docking of Progress M-15M was conducted for the purposes of testing the brand new Kurs-NA system, with the consequences of failure reduced due to the Progress having already offloaded all of its cargo to the ISS.
Kurs-NA uses less power than Kurs-A, and also replaces the function of five existing Kurs-A antennas into one antenna, thus allowing for the removal of four antennas from future Progress and Soyuz spacecraft, which will reduce the risk of a docking failure as the four antennas in question, which are deployed post-launch but retracted prior to docking since they extend forward of the Progress docking interface, will no longer be present.
Progress M-15M re-docking following Kurs-NA failure resolution:
While the original plan for the Kurs-NA tests was for Progress M-15M re-dock to the ISS roughly one day after its undocking, this plan was scuppered by the failure of the new Kurs-NA shortly after it was activated during the Progress’ first re-rendezvous attempt last Monday (23 July).
Although the re-rendezvous had already been initiated at the time of the Kurs-NA failure, the ISS was never in any danger, since the failure occurred when the Progress was still 161km away from the ISS, and the Progress was safely sent into a passive abort in a retrograde motion from the ISS.
The Russian flight control teams decided to wait until after the berthing of Japan’s HTV-3 spacecraft to the ISS on 27 July before re-attempting the re-docking, which gave the ground teams time to troubleshoot the Kurs-NA issue.
After numerous unsuccessful attempts to activate the problematic Kurs-NA, Russian engineers eventually discovered that the problem was caused by lower than expected temperatures on Progress M-15M. In an attempt to resolve the issue, engineers turned on all available heaters on Progress M-15M, which kept Progress M-15M at a constant 22 degrees, which in turn resulted in Kurs-NA activating successfully, paving the way for tonight’s docking.
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With the activated Kurs-NA successfully locking on to the passive Kurs (Kurs-P) on the ISS, the re-rendezvous, fly-around and docking to the ISS at the DC-1 port under the new Kurs-NA system successfully occurred at around 9:00 PM EDT 28 July/1:00 AM GMT 29 July.
Experienced Russian cosmonauts Gennady Padalka and Yuri Malenchanko aboard the ISS were however ready at all times to take over from the automated Kurs-NA via the TORU manual control system, should it have been needed.
Progress M-15M future activity:
Following Progress M-15M’s docking, the hatches between the ISS and Progress will be opened, and the Kurs-NA electronics box inside the Progress will be removed by the ISS crew, so that it can be returned to Earth, likely inside a SpaceX Dragon capsule, so that Russian engineers can analyse why the temperature issue affected the Kurs-NA system.
Once the hatches are re-closed, Progress M-15M will undock from the ISS for the final time on 30 July in order to make way for the arrival of the Progress M-16M/48P spacecraft, which will both launch to the ISS and dock just six hours later on August 1, in a test of a new fast-rendezvous profile for Progress and eventually Soyuz spacecraft. (The Progress M-16M fast rendezvous will be covered in a future article on NASASpaceflight.com.)
Following undocking, Progress M-15M will conduct two experiments – Khlopushka, from August 6-14, and Radar-Progress, from August 15-20, following which Progress M-15M will de-orbit for a destructive re-entry over the Pacific Ocean.
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