Progress M-18M docks with ISS following same day launch

by Pete Harding and William Graham

A Russian Progress resupply vehicle launched from the Baikonur Cosmodrome in Kazakhstan at 2:41 pm UTC on Monday, before docking at the International Space Station (ISS) six hours later. Riding on its Soyuz-U booster, Progress M-18M/50P again demonstrated the fast rendezvous option that will soon be used by crewed Soyuz missions.

Progress M-18:

Ahead of Monday’s events, the Progress M-16M (48P) resupply ship – which arrived at the station last August – successfully departed the Pirs docking compartment on the Russian segment – on Saturday. The Progress spent three more orbits in space before burning up above the Pacific Ocean.

The departure cleared the Pirs docking port for the arrival of the new Progress M-18M (50P) resupply spacecraft. The Progress is loaded with almost three tons of food, fuel, supplies and experiment hardware for the six crew members aboard the orbital laboratory.

Instead of performing the usual two day rendezvous profile to make its way to the ISS, Progress M-18M is performing an accelerated six hour (four orbit) rendezvous profile – the same type of maneuver that was successfully demonstrated on the Progress M-16M/48P mission in August, 2012 – and once again with Progress M-17M/49P in October, 2012.

The change from the traditional two day rendezvous to a new six hour rendezvous was detailed in a Russian document describing the new rendezvous profile, which was seen by

Fast Rendezvous Slide via L2The purpose of the maneuver is to shorten the time it takes between launches and dockings of Russian vehicles to the ISS, which usually stands at about 50 hours.

While the primary driver for this capability is to cut down on the amount of time that crews must spend inside the cramped Soyuz spacecraft between launch and docking, the maneuver is first being tested out with a few Progress vehicles in order to prove the concept, and demonstrate that it can be performed safely and successfully.

Progress vehicles can also benefit from the faster rendezvous however, as it allows time-critical biological payloads to reach the ISS very soon after launch, as other vehicles, such as Japan’s HTV and Europe’s ATV, can take up to a week to reach the ISS following launch.

With Monday’s fast rendezvous proving to be once again successful, it could be performed using a manned Soyuz spacecraft for the first time – maybe as soon as the Soyuz TMA-08M flight, which is currently scheduled to launch on March 28, 2013.

Docking of the Progress was confirmed at 8:35pm UTC – five minutes ahead of schedule.

Soyuz-U with Progress M18MThe Progress’ booster, the Soyuz-U 11A511U (137), was launched from the PU-5 launch pad at the famous Cosmodrome.

The Soyuz-U was developed as a standardised launch system, to replace the Voskhod and Soyuz and provide commonality with the Molniya-M. It first flew in May 1973, and in 1976 the original Soyuz, Soyuz-M and Voskhod were all retired, with subsequent launches of their payloads being conducted by Soyuz-U rockets.

The Soyuz-U2 configuration, which was optimised to use synthetic propellant allowing it to carry more payload, was introduced in 1982, and used for around 90 launches before being retired in 1995.

With around 750 flights, the Soyuz-U is the most-flown orbital launch system ever developed. It remains in service, and in the last few years it has mostly been used to launch Progress missions to the International Space Station, as well as occasional military payloads. Recent launches have used the Soyuz-U PVB version, which features additional fireproofing.

(Images via L2 and Roscosmos).

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