Progress MS-01 departs following off-nominal test
The Russian resupply vehicle Progress MS-01 (P-62) has departed from the International Space Station (ISS) for its End Of Mission (EOM) events. The departure came after a test was conducted on Friday which saw the cargo ship conduct a successful checkout of its manual docking control system. However, the spacecraft did suffer an off-nominal redocking, which is under investigation.
The upgraded MS range of the Progress vehicles now sport an external compartment that enables it to deploy small satellites, improved MMOD (Micrometeoroids and Orbital Debris protection, improved redundancy, communication links and navigation.
It also has a new TV camera which should aid views of the vehicle arriving at the Station (although it looked similar via NASA TV coverage during its December docking), which also has practical uses for controllers and those on board the Station, especially if manual control is required, should the Kurs NA digital system – also new for the Progress – fails.
Notably, the TORU backup system, used during a failure of Kurs, was not available for its docking, due to a system failure on the ISS.
This, in part, resulted in a test being carried out on Friday, where the Progress automatically undocked from the Pirs Docking Compartment of the space station to be manually be guided in to re-dock.
The 30 minute activity tested the newly installed manual docking system inside the station’s Russian segment. Progress MS-01 undocked from Pirs at 05:36 UTC on Friday.
After backing away to a distance of about 600 feet, Expedition 48 cosmonauts Alexey Ovchinin and Oleg Skripochka of the Russian space agency Roscosmos took manual control of the spacecraft, using a workstation in the Zvezda Service Module. Progress redocked under TORU control at 06:05 UTC.
The test included verification of software and a new signal converter incorporated in the upgraded manual docking system for future use in both Progress and piloted Soyuz vehicles in the unlikely event the Kurs automated rendezvous in either craft encounters a problem.
Technically the test was successful, with Roscosmos noting the “Progress MS has successfully carried out a test of the system improved remote manual spacecraft control – TORU (teleoperator control mode). All operations of the test program we have done successfully, and even made a few good pictures for the story.”
However, there was interest in the way Progress redocked with the Station, which showed a larger than usual amount of motion prior to the full retraction of the docking probe and hard mate.
While Roscosmos made no reference to anything being amiss, it is understood a controller noted “mishap at contact” over the loop. RSC Energia later noted “insignificant differences” in a small admission that there was an issue during docking, while citing the TORU test was successful.
It is believed the large motion was caused by the firing of Progress’ DPO thrusters along both the X and Y axis at contact.
Normally, with the ISS in free drift, the Progress fires the X axis thrusters to drive the docking probe into the cone on the port. However, the firing of the Y axis thrusters was not expected and can risk the probe becoming bent by the additional motion. The firing of the Y axis thrusters is understood to be under investigation.
A potential line of inquiry will be the events that occurred once the docking probe came into contact with the port’s cone.
The four DK1 sensors allow the ABU control system to know the point at which “contact confirmed” has occurred. That signal then provides orders for the firing of DPO thrusters in one direction to push the spaceship deeper into the cone.
The off-nominal event occurred after the DK2 sensors had emitted the “Latching” command. As such, with the docking probe now firmly inside the core, the DPO thrusters had no reasons to fire.
L2 ISS notes later explained that “immediately following capture, +X and +Y thrusters continued to fire for 65-70 seconds which was unexpected. The crew stopped the thruster firings by issuing a command from the TORU panel. The Progress dynamic oscillations were captured on video. The Russians have formed a commission to investigate.”
Thankfully, the probe appears to have avoided any damage, as it played a nominal role in the release of Progress MS-01 during the early hours of Sunday.
Once departed from the Station’s neighborhood, Progress MS-01 – loaded with trash from the ISS – was deorbited by Russian flight controllers to burn up in the Earth’s atmosphere over the Pacific Ocean.
(Images via Roscosmos).