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22:28 July 22, 2021
The MLM Nauka module successfully turned on the propulsion system and began to increase the altitude of its orbit, reports Roscosmos, which is also confirmed by independent observations using Doppler radar. Previously, an N + 1 source from the rocket and space industry reported that the first attempt to start the engines had failed.
MLM Nauka is the first new module in the Russian segment of the ISS in 11 years. Initially, it was planned to send it to the station in 2007, but the launch date was postponed several times, mainly due to the fact that experts found metal chips in the fuel system. More details on this and how Roscosmos tried to eliminate this technological flaw can be found in our “Fatal shavings” material.
The launch of “Science” took place on July 21 and initially went smoothly, but on July 22, Roskosmos discovered a problem in the fuel system. The N + 1 source said damaged membranes in the fuel system could potentially cause the module to run out of fuel to approach the ISS. Later it turned out that the first activation of the engines to raise the orbit failed.
But on the evening of July 22, Roskosmos reported that the module nonetheless activated the propulsion system and began to increase altitude. At first, a start-up test took place, which showed that the motors are capable of functioning normally, and then they were restarted for full orbit correction. As a result of the maneuver, the perigee of the orbit increased from 190 to 245 kilometers.
Update: Roscosmos has clarified the orbital parameters and the course of the maneuvers. The test engines were fired at 6:07 p.m. Moscow time, and the main impetus was given at 8:19 p.m. As a result, the apogee of the orbit increased from 345 to 364.9 kilometers, and the perigee rose to 230.4 kilometers, and not to 245, as the head of Roscosmos Dmitry Rogozin said earlier.
With the initial problems with the propulsion system resolved, the specialists were able to set a date for the undocking of the Pirs module, which the Nauka will arrive at – it is scheduled for July 24. Initially, it was to take place on Friday, but as soon as the ISS crew negotiated, we learned of the postponement.
Shortly before the official announcement from Roscosmos, Dutch astronomer Cees Bassa, who works at the world’s largest radio telescope, LOFAR, announced a probable orbit correction:
He followed the flight of the Proton-M rocket module and third stage using Doppler radar and compared them to the latest data on their orbits, received around 12:00 p.m. Moscow time. It turned out that the orbit of the third stage did not change, but that of the module increased – this can be judged by the fact that the flight took place 12 seconds later than the estimated time. Most likely, this means that the orbital speed of the vehicle has decreased due to the increase in orbital altitude.
Grigory Kopiev
https://nplus1.ru/news/2021/07/22/nauka-radar
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