A little while ago the SpaceX Dragon spacecraft was captured by the Canadarm2 robotic arm on the International Space Station. Alexander Gerst, assisted by his colleague Serena Auñón-Chancellor, managed the operation then started moving the Dragon to the berthing point at the Poisk module. The cargo spacecraft blasted off last Wednesday.
The Dragon spacecraft’s approach to the International Space Station follows a procedure that has become routine but remains long and delicate. The Station’s safety is the top priority so every little step of the Dragon gets checked. Only if all goes well in the spacecraft’s position and velocity they proceed with the next step and in case of any problems can be aborted at every step. Today the arrival was delayed following some communication problems with one of the TDRS satellites used by the ground crew to monitor the Dragon. The problem was solved switching to another TDRS satellite.
Tomorrow, the International Space Station crew will open the Dragon spacecraft’s hatch and will start unloading its cargo. As in various other resupply missions, there’s a group of mice whose health in microgravity conditions will be studied. After a period on the Station, they’ll be sent back to Earth.
The Dragon will leave the International Space Station with its new cargo. The CRS-16 mission will be completed with its descent into the Pacific Ocean, off the coast of California. This last phase is important as well because various in-depth analyzes of samples can be carried out only in specialized laboratories on Earth.
This first part of the CRS-16 mission went very well, with the consequence that people are talking about the problem that occurred at the Falcon 9 rocket’s first stage, which ended up in the Atlantic Ocean instead of landing in the Landing Zone-1 (LZ-1) at Cape Canaveral. This is the first failure after 26 straight controlled landing successes.
The cause of the accident is in the grid fins system used in landing maneuvers to orient the first stage and spin it and will be subject to examinations to understand the fault and if it can be prevented from happening again. There’s a hydraulic pump that powers the system and Elon Musk stated that they could add another to have a redundancy.
On Wednesday, the first stage started spinning in an anomalous way because of the wrong positioning of the fins. Live images of the landing were interrupted but then Elon Musk himself published them on Twitter: a tweet that shows the images from the point of view of the first stage as it spins and another in which its descent is seen from the coast. You can see the entire spinning phase of the first stage and the subsequent water landing that still didn’t destroy it. Musk stated that they’ll try to recover it but the first close exam shows damage so rapairing it might not make sense.
SpaceX vice-president Hans Koenisgman stated that the water landing in the Atlantic is the result of the first stage planning. Public safety is the priority for the landing system and the consequence is that following the anomaly caused by the fins it didn’t return to the mainland but remained above the ocean. Basically, despite the control problem, the landing system worked very well, managing to drive the first stage enough to avoid the mainland and therefore a potential danger to people.