Why is the Russian segment of the ISS module "Science" sent back for revision
The "Science" module developed by Russian scientists for the ISS was again sent for revision and elimination of the identified defects this time due to the forgetfulness of the assemblers. At the same time, sending the module into orbit was postponed indefinitely, since it is not known how long it will take to complete the revision.
The start of "Science" has been postponed again, so what is the reason
After completing the rolling procedure on the head fairing module, it was decided to return Nauka to the assembly and test box. Before that, representatives of Roskosmos reported that the assembly of the module was successfully completed, and tests of the module itself, the head fairing, and the transition compartment were also carried out.
Gazeta.ru learned about the reason why the module was returned to the installation and test module from its source in the department.
So, according to the source, the reason for the return was the missing thermal insulation of the screen-vacuum type on the star sensors.
This drawback was revealed when the entire installation had already come to refueling with fuel and various gases. After finding the deficiency and returning it to the "Energia" assembly and testing complex, it was practically a day to decide how to cover the sensors with insulation without removing the fairing. But as a result, the fairing still had to be removed and now a comprehensive solution is being worked out, including on the timing of the postponement of the launch.
Thus, the planned launch of the module into orbit, scheduled for July 15, 2021, is postponed, but how much is not yet clear.
Sensors and missing insulation
The star sensor, which turned out to be without insulation, vaguely resembles binoculars, the lenses of which are directed into outer space. In this case, the lateral edges of the sensor are black, and they will warm up quite strongly on the Sun.
For this reason, they are covered with a special “fabric” to maintain thermal balance. The applied screen-vacuum thermal insulation covers the housings of the sensors from exposure to sunlight and charged particles. In addition, this coating prevents the sensor elements from overcooling when the station is in the shade.
It is not known when the module will go to the ISS. I would like to remind you that initially "Science" was supposed to be launched into orbit 12 years ago, but due to the detected chips in the fuel system, the module was returned to the customer, and after careful revision and elimination of defects, the module was in standby mode for complex tests for several years old.
And here are new flaws that lead to a shift in the launch date. Well, we hope that this is a minor delay and Nauka will be launched into orbit and will significantly increase the Russian research power as part of the ISS.
I hope that the material was useful for you and thank you for your attention.