RSC Energia - Roscosmos: two-orbit spacecraft rendezvous profile features

July 10, 2018

Today, July 10, 2018, saw the launch of the cargo transportation spacecraft Progress MS-09 using Soyuz-2.1a launch vehicle. Used in the course of this launch for the first time in the history of spaceflight was a short two-orbit spacecraft rendezvous profile, which made it possible to reduce the time of flight to the ISS down to 3 hours.

First deputy general designer, chief designer of manned space systems of RSC Energia Sergei Romanov spoke about the features and [prospects of the two-orbit profile.

The main advantage of such a profile consists, first of all, in reducing the time of flight down to 3 hours which was done for the first time in the history of spaceflight. Neither Americans, nor Chinese have ever done this, - confirms Sergei Romanov. In the long run, the manned space missions are going to use a similar profile. But this will require several more launches of Progress.

Sergei Romanov: We are planning to perform 2 or 3 dockings of cargo spacecraft, and only after that this profile will be used on Soyuz spacecraft. That is, three hours after the launch the cosmonauts will find themselves onboard the ISS. It is not inconceivable that in the future the flight to orbit will turn out to be even shorter and a one-orbit profile will be used.

Earlier on, a four-orbit rendezvous profile (6 hours transit to the ISS) was used for dockings with the orbital station, today a two-orbit profile was implemented. In the long view, it will be possible to use a one-orbit profile, but this will already be the next step. The main objective in reducing the time of transit to the ISS is to make sure that the cosmonauts spend the shortest time within the small volume of the spacecraft, thus providing for them more comfortable conditions, - points out Sergei Romanov.

However, in order to implement a two-orbit profile, one needs to meet a number of strict conditions. The most important of them is to provide coplanar injection where the orbital plane of the ISS coincides with the injection plane of the spacecraft. We had failed to implement this profile twice on the previous cargo spacecraft, because after automatic aborts we had to switch to backup launch days, and on those dates the injection was not coplanar, that is, the orbits diverged, - explained the chief designer of manned space systems of RSC Energia.

But after introducing certain modifications, this profile could be used on a permanent basis. In the near future, in order to circumvent the existing constraints, the injection process will be jointly studied with RSC Progress with the objective to make the third stage of the LV perform an additional turn (through 1-1.5 degrees) to assure coplanar injection of the spacecraft, - said Sergei Romanov.




July 10, 2018
LV Soyuz-2.1a with SC Progress MS-09 is launched
June 6, 2018
LV Soyuz-FG with SC Soyuz MS-09 is launched

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