They may have lost the second stage, though.
Yes, very much looks like it.
I wonder how much of the second stage flight is autonomous and if they need to continually need to give it a go to continue, or if it aborts automatically after some time of lost telemetry. But maybe it already exploded anyways.
The flight control loops are strongly latched. They are constantly checking the state of discretes, control surfaces, and intended guidance. If any critical parameter gets out of range for a period of time or if any group of standard parameters gets out of range the vehicle will simply cease powered flight.
In the Space Shuttle, given that it was human rated, the "Range Safety" system was completely manual. It was controlled by a pair of individuals and they manually made the call to send the ARM/FIRE sequence to the range safety detonators.
The automated FTS is triggered if it leaves a pre-defined corridor (which is wider than the flight plan - substantially so in some places).
The AFTS has independent, hardened, validated inertial measurement systems.
Probably self destructs if anything goes wrong
"we currently don't have comms on the ship"
edit: the spacex stream just confirmed the loss.
Telemetry showed them lose engines one at a time, which isn’t a great sign.
I think that’s the normal shutdown order to reduce shock, the timing was exactly the expected second stage shutoff time if I understood it correctly.
Incorrect it failed asymmetricaly in such a way that would pitch the vehicle in circles. Normally the sea level raptors are turned off and the space raptors are slowly brought down together.
One of the three sea level engines went out and stayed out. It didn’t look normal. The numbers stopped updating with one engine still on.
Right, I just watched it again and it didn’t look normal.
But interesting that telemetry showed the failures starting a few seconds before loss of telemetry, the videos posted here show a massive explosion later on. So something was going wrong for some time before, and the explosion was only a consequence of that.
Or it was the FTS reacting to the engine failures.