Flights of the American cargo ships Cygnus to the ISS may be interrupted for an indefinite period due to the US running out of stocks of Russian RD-181 rocket engines. These engines are used on Antares rockets, which are the regular carriers of Cygnus cargo ships.
According to the head of Roscosmos Dmitry Rogozin, the United States has only four RD-181 engines left, enough for two launches of Antares rockets. What they intend to do next in the United States is unknown; deliveries of Russian rocket engines to the Americans have been stopped as part of retaliatory sanctions. This was announced at the beginning of March this year. In addition to stopping deliveries, Russia also stopped servicing engines already delivered. We are talking about the RD-180 used on the American Atlas-5 and RD-181 missiles used in the first stage of the Antares missiles.
As a result of our retaliatory sanctions, the United States has only 4 RD-181 engines left. They are enough for two Cygnus launches, Rogozin said.
The press service of Roscosmos clarified that the United States has a way out of this situation, they just need to adapt the Cygnus cargo ship to another carrier. After a few years and large financial costs, this issue will be resolved. Another option is to try to negotiate with Russia on the supply of engines.
Earlier it was reported that the United States was unable to correct the height of the ISS orbit using the engines of the Cygnus cargo ship docked to the station. NASA has not yet given a reason. The correction of the ISS orbit, carried out by the US cargo ship Cygnus on Monday, June 20, was interrupted for an unspecified reason. Whether attempts to raise the station will continue is still unknown, the American “truck” should leave the ISS on Thursday, June 23.