In a few hours, an event will occur, which serves as another confirmation of the fact that it is getting cramped in near-earth space: the Progress MS-17 cargo vehicle will fly in close proximity to two objects belonging to the category of so-called space debris. Funnily enough, they both owe their origins to SpaceX.
According to the official press service of Roscosmos, the rapprochement will take place on July 2, at 00:32 Moscow time. First, Progress MS-17 will fly at a distance of about one and a half kilometers from the decommissioned Starlink 1691 satellite. And after just three minutes - not far (500 meters) from a fragment of the upper stage of the Falcon 9 rocket. Both approaches will take place just three and a half hours before the cargo ship docks with the International Space Station (scheduled for 04:02 Moscow time).
The situation is monitored by the Central Information and Analytical Center of the Automated System for Warning of Dangerous Situations in Near-Earth Space TsNIIMash. It is important to note that the approach has not yet been confirmed and all distances, as well as time, have been calculated approximately. There is no immediate danger of space debris for the Progress MS-17 mission. At least one more orbit correction is planned in the "truck" flight plan, so that the situation can radically change for the better.
In addition, when it comes to the approach of objects of comparable masses in outer space, we mean the relatively small distance between them. According to astronomical standards, 100 kilometers is almost close contact, but in near-earth space, proximity of a few kilometers is considered potentially dangerous. This does not mean that the risk of collision becomes high (it is still unusually small), it is just that in astronautics it is customary to reinsure itself several times, especially since there is always an error in the calculations.
The Progress MS-17 spacecraft will deliver more than two tons of payload to the ISS. Among them:
- 470 kilograms of fuel for refueling the orbital laboratory;
- 420 liters of drinking water;
- 40 kilograms of air and oxygen;
- 1509 kilograms of equipment, consumables, maintenance items, experimental stowage, clothing, food and hygiene products, and sanitary and medical controls.
According to the portal Space.com, most likely, the "fragment of the Falcon 9 rocket" is the spring thrust of the Starlink satellite dispensing system (dispenser). Four of these fit into the second stage and hold stacks of compact spacecraft together like an elastic band on a luggage trolley. What makes the Starlink dispenser special is that it consists of a minimum of parts: four locking rods and a base for distributing the payload mass. The satellites simply lie on top of each other and when the thrust is released, they smoothly crumble in space.
Since the second stage rotates slowly at the time of dilution, Starlink devices receive a small impulse from it, directed in different directions. Satellites can collide at a low speed, this does not affect their performance.Under normal conditions, the spring rods simply fly away from the stage and then, in a matter of weeks, enter the atmosphere back, where they burn out without a trace. But in August 2020, one launch (v1.0 L9) took place with the launch of the Starlink vehicles and the associated load into a higher parking orbit than before. Because of this, the parts of the dispenser spent more time in space than usual and turned into space debris.
After separation from the Falcon 9 upper stage, the Starlink spacecraft are lifted into working orbit using their own xenon electric rocket engines. If the satellite is out of order for some reason, the same units are used to de-orbit and return to the dense layers of the atmosphere, where they almost completely burn out. This is exactly what the device with the number 1691 is doing now, so for the time being it is possible to call it garbage only in a figurative sense.