United they stand – Trace Gas Orbiter and Schiaparelli are joined
16 February 2016The Trace Gas Orbiter and Schiaparelli are now in their launch configuration. The ExoMars 2016 spacecraft will remain united until 16 October, when the entry, descent and landing demonstrator module will separate from the orbiter to descend to the surface of Mars.
The mating of the Trace Gas Orbiter and Schiaparelli began on Friday 12 February with the two spacecraft having been transferred into the fuelling area, where a mounting platform surrounding the orbiter facilitates the activities that need to be done about 4 m off the ground.
|Transfer of the Trace Gas Orbiter (on 10 February) and Schiaparelli (on 12 February) to the fuelling area, prior to being mated. Credit: ESA - B. Bethge|
TGO and Schiaparelli are mechanically linked with the main separation assembly (MSA), which attaches to TGO with 27 screws. The MSA holds onto Schiaparelli with three separation mechanisms comprising compressed and angled springs that are held by non-explosive actuators (NEA). When the NEA's are released on 16 October, as the spacecraft approaches Mars, Schiaparelli will be gently pushed away from TGO, at the same time being imparted with a rotation that will serve to stabilize its atmospheric entry.
|Schiaparelli being mated with the Trace Gas Orbiter on 12 February. Credit: ESA - B. Bethge|
Although this was the third time the two spacecraft have been mated – the previous occasions being in Cannes during integration and testing – it was the first time it was done with Schiaparelli fuelled, which required extra safety precautions to be applied.
The next day, Saturday 13 February, all the electrical connections between the two spacecraft were made, which meant that some functional checks could also be started. These checks, which provide a means of monitoring that all systems are behaving as expected and that no problems have been introduced by any of the preparations, continued throughout the weekend and were completed on Monday 15 February.
Meanwhile, on Sunday, specialists from the Airbus Defence and Space team began their preparations for bonding the last few tiles on Schiaparelli. Although most of the tiles had been placed and sealed last week, a few places on the heat shield had remained 'open' since these were the sites of hooks for the equipment that is used to lift Schiaparelli into place on the TGO. With this task completed the hooks could be removed and the final tiles placed and sealed. These will be finalized on Wednesday 17 February. (The bonding of the tiles requires some days to allow the bonding agent to cure before the final, finishing touches can be applied.)
This week, on Tuesday and Wednesday, TGO and Schiaparelli will 'phone home': they will be connected (via the Network Data Interface Unit (NDIU)) to the mission operations centre at the European Space Operations Centre (ESOC), to run the last of the system verification tests (SVT-2b) on the spacecraft.
By the end of the week, the spacecraft will be ready for fuelling of the Trace Gas Orbiter.