Soyuz TMA-12M docking delayed following problematic burn
Soyuz Commander Alexander Skvortsov, Flight Engineer Oleg Artemyev and NASA’s Steven Swanson were on a fast track launch to the International Space Station (ISS) on Tuesday. A nominal launch, via the Soyuz FG carrier rocket from the Baikonur Cosmodrome in Kazakhstan at 5:17 pm EDT (9:17 pm UTC), was set to result in a six hour trip to the Station. However, a problem with a key burn delayed rendezvous by two days.
Soyuz TMA-12M:
As with a number of previous Soyuz and Progress launches, Soyuz TMA-12M was using the short cut route to the ISS, avoiding the two day journey of the past.
First carried out for a crewed mission by Soyuz TMA-08M, the well practised procedure was initially demonstrated on recent Progress resupply missions.
The desire to dock to the ISS after just six hours stems from the fact that spending two days in the cramped interior of the Soyuz along with two other crewmates is known to be a stressful and uncomfortable time for astronauts and cosmonauts, many of whom are suffering from symptoms of space sickness at the same time.
Thus, being able to go from the ground to the ISS in a single day will be a big advantage to Soyuz crews.
Such a fast rendezvous was never attempted before as it requires extremely precise orbital adjustments from the ISS, and extremely precise orbital insertion by the Soyuz-FG booster, which was only deemed possible following a study conducted last year, which showed that such accuracy was achievable with the existing Soyuz-FG booster and modernized Soyuz TMA-M series spacecraft.
Following the launch of the reliable Soyuz FG rocket – along with a successful orbital insertion shortly thereafter – the Soyuz TMA-12M was immediately tasked with performing the first two engine burns on its first orbit of the Earth, which were pre-programmed into the Soyuz’s on-board computer prior to launch.
On the second orbit, actual orbital parameters were be uplinked from a Russian Ground Site (RGS), which allows for a further eight rendezvous burns to be performed over the next five hours of flight.
During this time, the Soyuz crew will be able to unstrap from their Kazbek couches and enter the Orbital Module (BO) to stretch their legs and use the bathroom facilities.
While the crew were expected to dock to the station’s Poisk module less than six hours later at 11:04 pm, a problem during the “Dv3″ burn resulted in mission controllers opting to move to a new flight profile that will allow for Soyuz to arrive in two days time.
It was later revealed the 24 second burn did not occur, due to an attitude problem with the Soyuz. Russian controllers are still evaluating the root cause of the issue. However, it is understood the Soyuz TMA-12M’s flight computer didn’t command the spacecraft to proper attitude for DV3 burn, resulting in an automated “no burn” response.
Once Soyuz eventually arrives, they will be greeted by Expedition 39 Commander Koichi Wakata of the Japan Aerospace Exploration Agency, the first Japanese astronaut to lead an expedition, and Flight Engineers Rick Mastracchio of NASA and Mikhail Tyurin of Roscosmos.
Swanson, Skvortsov and Artemyev will remain aboard the station until mid-September. Wakata, Mastracchio and Tyurin have been aboard the orbital outpost since November 2013 and will return to Earth May 14, leaving Swanson as the Expedition 40 Commander.
The new crew will also be joined by another new arrival in a matter of days, as SpaceX’s CRS-3/SpX-3 Dragon prepares for her launch to the ISS on March 30.
It’s been a busy period on board the orbital outpost regardless, with the Station recently involved in a rare debris dodge.
Known as a Pre-Determined Debris Avoidance Maneuver (PDAM), the ISS utilized the new software version (8.07) of Zvezda’s command and control computers – which was loaded at the beginning of December 2013 – to fire the Service Module thrusters to remove a red conjunction threat from a dead weather satellite.
“A PDAM was successfully executed to avoid a piece of space debris (METEOR 2-5) that was tracking as a RED conjunction. This was the first PDAM using the SM 8.07. All systems performed as expected,” noted L2 ISS Status Report information.
Just days later, another threat was evaluated, namely the two Gravity Recovery And Climate Experiment (GRACE) satellites.
“Potential Conjunction: TOPO (Trajectory Operations Officer) continues to monitor the updates for Object# 27391 (Grace1) and Object #27392 (Grace2),” added L2 status.
“The conjunction is now classified as a high concern. TOPO will begin modeling Pre-Determined Debris Avoidance Maneuver (PDAM) options to ensure that ISS avoids all the conjunctions that are currently modeling. TOPO has confirmed that there is enough margin in the ISS downstream phasing plan to accommodate a PDAM.”
However, as the conjunction threat was further evaluated, it was determined that the threat would pass safely by the ISS. These two satellites are in a decaying orbit and are expected to end their lives in a few years times via a destructive re-entry.
Meanwhile, An alarm of a different sort occurred on the Station this week, as the Station crew were awoken by a false set of warning annunciations.
“Emergency Events in Russian Segment: Simultaneous Russian segment emergency alarms annunciated during crew sleep. MRM-2 erroneously reported indications of a rapid depressurization, a fire, and a toxic atmosphere,” L2 Status reports added.
False alarms can occur on the Station, sometimes caused by dust entering the sensors. However, in this case, the cause was related to a computer fault.
“It is believed the alarms were triggered due to a communication issue between the MRM-2 terminal computer [TBY-1] & the Service Module Central Computer (ЦВМ). CSA-CP readings confirmed that no fire was present. Later in the day, a FGB smoke event was annunciated.
“CSA-CP readings again showed no signs of smoke or fire.”