The never-ending run of supply missions to the International Space Station (ISS) continued on Wednesday, with the next Russian Progress cargo vehicle launched on a fast rendezvous, six hour “launch-to-dock”, mission. Progress M-24M (P56) was lofted uphill via a Soyuz-U launch vehicle from the Baikonur Cosmodrome in Kazakhstan at 21:44 GMT, ahead of docking to Pirs just six hours later.
The latest Progress rode to orbit on the Soyuz-U carrier rocket, following launch from the PU-5 LC1 ‘Gagarinskiy Start’ (17P32-5) launch complex at the famous Cosmodrome.
The Soyuz-U was developed as a standardized 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 optimized 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, as well as occasional military payloads.
Once orbital insertion was achieved, the race to hook up with the ISS, in just six hours, requires the first of two engine burns on the vehicle’s initial orbit of the Earth. The requirements were already onboard the Progress’ computers.
With all going to plan, the second orbit required the help of ground controllers, with actual orbital parameters uplinked from a Russian Ground Site (RGS), allowing for a further eight rendezvous burns to be performed over the next five hours of flight.
This fast rendezvous technique has been successfully employed on a number of Progress and Soyuz flights lately.
However, there was a problem during the “Dv3” burn on the Soyuz TMA-12 mission – which resulted in mission controllers opting to move to a new flight profile that allowed for Soyuz to arrive in the previously used two day rendezvous profile.
It was later revealed by sources that the 24 second DV3 burn did not occur due to an attitude problem with the Soyuz that lofted it into orbit – an error of just one degree.
This was apparently related to an over-performance of the Soyuz FG rocket – resulting in Soyuz being in a higher orbit that planned. As such, the TMA-12M’s flight computer provided an automated “no burn” command, due to the incorrect attitude of the vehicle.
Controllers opted to move to the back up plan of a two day rendezvous, with all burns relating to this flight profile conducted without issue. The Soyuz – with its three member crew – successfully docked with the MRM-2 port two days later.
For Progress M-24M’s arrival, the usual requirement of bidding farewell to a previously docked Progress was conducted earlier this week.
Progress M-23M undocked at 21:44 UTC on July 21, before departing the immediate neighborhood of the ISS.
It will still enjoy a swansong mission, participating in the Radar-Progress experiment – from July 26 to July 31 – for measuring the effects of propellant exhaust on the Earth’s ionosphere.
It will then end its life, de-orbiting on August 1 for a destructive re-entry.
Taking its place was Progress M-24M, filled with nearly three tons of food, fuel and supplies to the Station, which is part of the vital run of supplies required by the ISS, especially during this post-Shuttle era.
It is also be carrying 45 snailonauts, with the slimy passengers set to be part of Russian experiments in micro-g.
Progress joined another recent arrival, Orbital’s ORB-2/CRS-2 Cygnus, which also brought an array of new supplies to the Station’s crew.
(Images: via Roscosmos, NASA and L2’s Special Sections)
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