SpaceX’s Dragon cargo vessel launch was exciting and the engine flameout added a bit of drama to the historic event. Now we find out that more than an engine was lost in the mission. An Orbcomm communications satellite (a OG2 prototype spacecraft) was riding in the “trunk” of the Falcon 9 rocket. The engine failure forced an early release of the satellite – in too low an orbit. Orbcomm confirmed today that the satellite has “deorbited” (where it landed we do not know).
Secondary payloads in these commercial flights will likely be a common occurrence and in some instances, we will likely never hear about the extra cargo being dropped off on the way to their destination (or beyond the destination if a secondary burn is used to deposit the satellite in an even higher orbit). These secondary payloads do take a back seat to the primary mission though, as evidenced with this week’s satellite drop.
When the Falcon 9 rocket lost pressure on one Merlin 1C engine, it caused the engine to shut down. Falcon 9’s onboard software automatically recomputed its ascent profile to compensate for the lost engine. This meant the remaining engines had to burn longer to stay on course and intercept the space station at the right rendezvous point. A second-stage burn that was supposed to loft Orbcomm’s satellite into a higher operational orbit was called off. Dropping the satellite any lower would have threatened the orbit of the space station.
“While there was sufficient fuel on board to [lift the satellite], the liquid oxygen on board was only enough to achieve a roughly 95 per cent likelihood of completing the second burn, so Falcon 9 did not attempt a restart. The priority here was to protect the space station.”
Orbcomm confirmed today that the satellite has deorbited and that they have filed a claim against an insurance policy that covered the spacecraft for up to $10 million. Orbcomm commented:
“We appreciate the complexity and work that SpaceX put into this launch. SpaceX has been a supportive partner, and we are highly confident in their team and technology.”
SpaceX notes that Orbcomm understood the risks involved and their full constellation of 18 satellites will be launched next year.
