In my last Space Sunday update, I wrote about the comings and goings at the International Space Station (ISS), including the launch of the long-overdue Russian Nauka Multipurpose Laboratory Module (MLM), which at the time of that article was on its way to rendezvous and docking with the station having been lifted into orbit by a Proton M launcher on July 21st.
Designed to provide further dedicated space for Russian activates on the ISS, the 20-tonne module combines additional living space with working space, cargo storage, a dedicated external robotic arm that is capable of “walking” around the module using its two manipulator / mounts, courtesy of the European Space Agency), and an attitude control system to supplement those already on the station. It is the largest component Russia has provided for the ISS, and its launch – whilst 14 years overdue – is part of an effort by Russia to boost its space programme.
However, not long after the module reached orbit there were reports it was encountering some issues with a number of systems – including the thrusters. Neither Roscosmos nor NASA commented on these reports, and they apparently did not delay the planned rendezvous and docking at the station.
This took place at 13:29 UTC on Thursday, July 29th, when Nauka made an initial “soft dock” with the station following a fully automated approach to the ISS, monitored by cosmonaut Oleg Novitsky aboard the station, who sat at a control station that would enable him to take over manual control of the module should it become necessary. Nauka docked at a port on the Zvezda module that had been vacated earlier in the week by the 20-year-old Pirs docking / mini- science module. This had been towed away from the station by a departing Progress automated resupply vehicle, with both Pirs and the Progress vehicle burning up on re-entering the Earth’s denser atmosphere. The soft dock was followed by a confirmed “hard” dock, and things then appeared to be set.
However, at 16:34 UTC, the module’s thrusters started firing of their own accord. No warning was given, and the firings were enough to cause the station to lose attitude control eight minutes later, rolling as much as 45º out of orientation. The cause of the problem was not initially known; however in subsequent updates, Roscomos blamed the issue on a software glitch and / or human error.
There was such euphoria after docking, people relaxed to some extent. Perhaps one of the operators didn’t take into account that the control system of the block [Nauka] will continue to adjust itself in space. And it determined a moment three hours after docking and turned on the engines.
– Roscosmos chief Dmitry Rogozin, speaking on Russian radio
Rogozin also suggested the problem didn’t last that long, stating it was “quickly countered by the propulsion system” on the Zvezda module. However, NASA reports that overall, the station remained out of orientation for some 47 minutes before returning to its proper attitude.
That was a pretty exciting hour!
– NASA’s human spaceflight chief Kathy Lueders
During this time there were two drops in communications between the station and the ground, and the period of control loss was enough for NASA mission managers to advise the US / international crew on the station to ready the Crew Dragon capsule Endeavour for possible departure as a precautionary measure, the order remaining in place until it had been confirmed Russian ground controllers had inhibited Nauka’s thrusters to prevent any recurrence. However, whilst the order was given US ISS program manager Joel Montalbano emphasised there was never any significant danger for personnel on the station, and the ISS did not appear to suffer any damage.
With the ISS back under control, the crew and mission controllers Earthside commenced a period of careful check-out of the station and all of its systems, with the Russian crew members working to open the airlock doors to Nauka and check the module’s interior. While this work has continued through the weekend, both Russia and the US have been keen to emphasise that things aboard the ISS are pretty much business as usual once more.
There was, however, one casualty following the situation: the planned launch of the CST-100 Starliner, due to make its second attempt of its uncrewed Orbital Flight Test to the station ahead of being certified for crew operations. Starliner’s launch had been set for Friday, July 30th, the day after the Nauka docking. However, the decision was taken to delay the launch, and the vehicle and its Atlas V launcher were rolled back from the pad on July 30th.
Scheduling conflicts with other launches from Cape Canaveral mean that Starliner’s launch will now not take place until Tuesday, August 3rd at the earliest – and that is subject to how the weather behaves.
Currently, the launch is set for 17:20 UTC on the 3rd, but there is around a 40% chance things could get derailed by thunderstorms. However, once fuelled and ready, the Atlas V is capable of an “instantaneous” launch should a break occur in the weather, and launch managers are hoping the worst of the weather will hold off until after the launch window. Should a scrub be called for the 5rd, a further window will open on Wednesday, August 4th.
Continue reading “Space Sunday: ISS difficulties, HLS and making a moon”