The latest Russian Progress cargo vehicle has docked with the ISS on Tuesday, following its launch on a fast rendezvous, six hour “launch-to-dock”, mission. Progress M-26M (58P) was lofted uphill via a Soyuz-U launch vehicle from the Baikonur Cosmodrome in Kazakhstan at 11:00 UTC, ahead of an docking to the aft port of Zvezda less than six hours later.
The latest Progress rode to orbit on the Soyuz-U carrier rocket, designated 11A511U Soyuz-U (142), following launch from the PU-5 LC1 ‘Gagarinskiy Start’ (17P32-5) launch complex at the famous Cosmodrome.
The previous Progress was lofted on a Soyuz 2-1A for the first time.
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, required two engine burns on the vehicle’s initial orbit of the Earth. The requirements were already be onboard the Progress’ computers.
With all going to plan, the second orbit required the assistance of ground controllers, with actual orbital parameters uplinked from a Russian Ground Site (RGS), allowing for a further eight rendezvous burns that were 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 most Progress arrivals, the usual pre-docking requirement involves the bidding farewell to a previously docked Progress.
However, for Progress M-26M’s arrival, the aft Zvezda port was vacated by ATV-5, the final ESA Automated Transfer Vehicle to complete an ISS mission.
The undocking was conducted on Saturday, ahead of a bitter-sweet destructive re-entry the following day.
The original plan was for the ATV-5 to spend a few weeks on orbit, ahead of a shallow dive return, allowing for additional data on the forces involved with entry. However, this was cancelled due to a loss of redundancy on the ATV systems.
Taking its place on the Station, Progress M-26M is delivering an estimated 2370 kg 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 and not least because the United States is currently down to just one available Commercial Resupply Services (CRS) spacecraft – SpaceX’s Dragon.
Orbital’s Cygnus spacecraft awaits a return to operations atop ULA’s Atlas V, following the loss of the CRS-3 vehicle during the Antares mishap.
Docking of the Progress successfully occurred at 16:57 UTC..
(Images: via Roscosmos, NASA and L2’s Special Sections)
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