Bad news again! (At least if the Russian account below is to be believed, and I'm definitely inclined to believe it.) Apparently the problem with Nauka is that its main orbit-maneuvering engines won't fire. While they did do at least two orbit-modification burns, reportedly these were done with much smaller maneuvering thrusters instead of the bigger maneuvering engines. I'd question whether they have enough thruster fuel to effect the necessary orbital changes. So unless they can get the main engines going, I fear that Nauka may be doomed. The account below speaks of one of their sources saying that the main engines have been brought back on line. Roscosmos still isn't saying very much officially.
Whatever the truth with all that, NASA isn't streaming the disconnection of the old Pirs module from the Space Station, something that was due to happen today but apparently isn't.
Translation of the Russian follows:
https://nplus1.ru/news/2021/07/24/rise
The orbit of the "Nauka" module has risen after correction by about 20 kilometers
11:53 24 July 2021
The orbit of the Russian module MLM "Science", which flies to the International Space Station, after turning on the engines on Friday, July 23, has grown by about 20 kilometers, according to data from the US military, published on the specialized website Space-track.org. Roscosmos confirmed that two corrective maneuvers took place on Friday, but did not report data on the new orbit.
The multifunctional laboratory module "Science" successfully launched from the Baikonur cosmodrome on July 21, but soon after the launch on board the module, according to industry sources, there were problems in the fuel system, which made it impossible to start the main engines. On the evening of July 22, Roskosmos reported that Nauka was able to start the engines , which made it possible to increase the perigee of the orbit from 190 to 224 kilometers. However, by the nature of the operation of the engines, it became clear that the orbit correction was carried out not with the help of the main correction and rendezvous engines (BCS), but with the auxiliary mooring and stabilization engines - DPS (we talked about them in more detail in our blog “What engines did Science include? ).
On Friday evening, a source of N + 1 reported that the problems in the fuel system had been eliminated, and then there was evidence that for the first time it was possible to start the main engines of the booster station . In addition, another correction was made earlier in the day with the help of auxiliary engines. After it, the orbit rose by about a kilometer.
Judging by the data of the American military, the semi-major axis of the MLM orbit has grown by almost 20 kilometers from the night of July 23. At 03:04 Moscow time on Friday, July 23, the perigee of Nauka's orbit was at an altitude of 224.3 kilometers, with an apogee at 347.5 kilometers. At 07:55 on Saturday, July 24, the perigee rose to 238.4 kilometers and the apogee to 370.3 kilometers.
Roskosmos does not provide information on which engines of the module were used to correct the orbit. On Saturday, according to the state corporation, new "impulses for further orbit building" are planned.
You can read about the history of the MLM module in our material "Fatal shavings" , and about how the module was supposed to fly to the ISS - in the material "Seeing the Science" .
Sergey Kuznetsov