The Nauka module docked to the ISS, despite the fact that a week ago it was declared “almost lost” and “de-orbiting”. Today at 16:29 Moscow time, the docking of Nauka and the ISS has been successfully completed!
Why did the flight of “Science” attract such close attention? And what difficulties accompanied the module on its eight-day journey to the International Space Station? About this – in the material FAN.
vk.com  / Press service of Roscosmos
Spiteful critics from “Alpha Centauri”
Even before the launch of Nauka from the Baikonur cosmodrome on July 21, some critics of the Russian space program said that there was “nothing to launch there,” stressing that the module had spent more than 20 years in assembly shops, having experienced several painful stages of reworking the main systems.
The state of “Science” a year ago was indeed far from ideal. Many of the module’s systems are either outdated or have exhausted their warranty resource while still on the ground.
This was reflected in the question posed to the head of Roscosmos, Dmitry Rogozin. In February 2020, they asked if he would sign a “death warrant” for himself by allowing an unusable module to be launched into orbit? To which Rogozin replied that the “death sentence” will be signed by the one who will allow to destroy and write off the finished machine capable of flying into space.
Doubts about Nauka’s ability to rendezvous and dock with the ISS received an additional impetus immediately after the normal shutdown of the Proton rocket, when telemetry information from the module briefly stopped flowing through the tracking station near Barnaul. Almost immediately based in Ukraine or Poland, the Internet channel Alpha Centauri, dedicated to space issues, said that no confirmation was received from Nauka about the working capacity of the Kurs rendezvous system and the main engines of the DCS (correction and rendezvous engines).
“The module will soon fall to Earth due to the failure of these systems!” – the hunters foreshadowed.
I must say that both systems are critical for docking with the ISS. “Kurs” provides navigation at the final stage of accurate rendezvous, and pulses from the space station are needed to correct the module’s orbit.
Fuel was added to the fire by the fact that Roskosmos did not comment on the issue of possible malfunctions in the module on the first day, only confirming the loss of telemetry over Barnaul.
Global Look Press  / roscosmos
Day of agonizing wait
On July 22, Nauka did not complete the planned first orbit correction out of the set four, remaining in a low launch orbit. The danger of such an orbit is that it has a very low point of maximum approach to the Earth, perigee: initially it was only 190 km. The module could have been in such an orbit for no more than one week, after which deceleration in the upper atmosphere would inevitably lead it to our planet.
A number of commentators immediately began referring to “competent industry sources”, claiming that the module had a problem with the fuel system. Considering that the large-scale alteration of “Science” on the ground included precisely the replacement of the fuel system, reports of such a problem looked as plausible as possible. Due to problems with orbit correction, Roskosmos even postponed undocking of the Pirs module from the ISS, which was to be replaced by Nauka.
However, in the evening of the same day, the press service of the state corporation reported that the test firing of the propulsion system of the Nauka module and the orbit formation impulse had been worked out normally – and the perigee of the orbit had been raised to 230 km. After that, on July 24, the Pirs module was undocked from the ISS and flooded in the remote region of the Pacific Ocean, where spiteful critics had recently awaited the “inevitable” fall of Nauka.
It is still unknown what happened to the booster station and in what mode they were leading “Science” to the station. We can only say that due to the wasted time, instead of four corrections, “Science” in fact had to use one more. The last, fifth orbit correction took place on July 28, after which the module entered the trajectory of the final rendezvous with the ISS.
Three days before that, at the moment of the closest approach of Nauka to the ISS orbit at its apogee, its Kurs docking system was routinely checked. In the evening of the same day, another test of the “Course” was carried out – then the operability of both sets of equipment was confirmed, which proved the readiness of the “Nauka” for docking.
On July 27, the same Kurs set was tested on the ISS: cosmonauts Oleg Novitsky and Pyotr Dubrov tested the system in manual mode in case of a sudden failure of automation during docking.
After undocking the Pirs module from the ISS, which took place on July 24, the Russian cosmonauts on the ISS made the necessary preparations to receive the Nauka. On July 26-27, the Kanadarm-2 robotic arm, using a camera installed on it, examined the Zvezdy docking station, where Nauka would dock, to check its readiness for docking.
After that, Roskosmos reported that the analysis of the Canadarm-2 data on the docking station previously occupied by the Pirs module showed that there were no mechanical hindrances for the Nauka docking. This made it possible to avoid an unscheduled spacewalk in order to prepare the docking station.
By 16:00 the module approached the ISS at a distance of less than 2 km. At such small distances, the inexorable laws of celestial mechanics that cause spacecraft to move in bizarre orbits and synchronize them precisely, miraculously weaken. Only the relative speeds become important, which drop to several meters per second – it is at this speed that the approach takes place, while the docking proceeds at even lower speeds – less than ten centimeters per second. This is extremely important, given the mass of docking objects, amounting to tens of tons for Nauka and hundreds of tons for the ISS.
Finally, at 4:29 pm Moscow time, the Nauka module softly docked with the Russian Zvezda module, completing its eight-day journey to the International Space Station.