I have watched last Falcon 9 landing and launch, but during landing screen froze. I have heard that it didn't landed successfully, so what happened with it, does anyone know?
The craft experienced a RUD, which is Elon Musk's technical term for a Rapid Unscheduled Disassembly. It thus became a pile of spacecraft parts on the deck of the landing craft, and also burnt quite a bit. SpaceX will shortly release images of the landed craft.
The debris will be taken back to Canaveral for forensic analysis to improve future landings.
Images of the debris back in port are shown here:
SpaceX has an interesting product in the Falcon 9 recoverable, since it has a suite of option. Lowest performance missions, can land the first stage back at the launch site (RTLS - Return to Launch Site). On missions that need more performance, typically GTO/GEO missions, they can land down range on the ASDS ship. Finally, if you needed max performance and wanted to pay for it, there is an option of an expendable first stage.
This was a dual launch GTO mission, so not quite at the absolute max of performance but pretty close.
They have said that they are working on tricks to eke out more performance for landing, by trying a three engine landing burn instead of the previous single engine burn. This saves on gravity losses by burning harder and faster.
The longer you burn, the more you are fighting gravity, and they are close enough to the edge that this matters.
As a further twist, they have tried a 1-3-1 burn pattern. First one engine starts slowing it down, two more engines spin up and slow it down hard, and then shut down and only one engine is finally used to land.
In this case, one of the engines either had a slow start, or did not properly get up to full thrust and they were probably unbalanced. Or it could be they ran out of fuel and one engine was not getting fed properly.
We know a few bits of information:
- The landing was initially thought to be hard.
- The landing video shows it at a near hover for ~2 seconds.
- It seems it ran out of fuel (Well, oxidizer).
Putting all of this together, I imagine some kind of a sensor issue. Either the rocket thought it was going faster than it actually was, and as a result hovered and ran out of fuel, or it didn't know how far away the ground was, and a similar issue happened.
The Falcon 9 uses 3 of its engines to land. In this case one of the engines didn't work properly and did not give enough thrust and the other 2 engines did not compensate, so it hit the platform at too high a speed, broke up and exploded.
SpaceX is working on a system which will compensate for a weak engine, they say they want to test it later this year.