During a press conference after liftoff, Musk said it was dicey whether the second stage would power up at all. The fuel could have frozen, the oxygen boiled off, or the avionics failed, as the rocket spent more than five hours in our planet’s high-radiation Van Allen belts before firing up.

Usually spacecraft punch through the belts as quickly as possible to minimize the risk of damage. After hours of charged particles bombarding the podule, it still worked just fine. Ish. Maybe it was performing a touching tribute to Tesla’s autopilot software.

The payload was supposed to get into an orbit around the Sun, and skim Mars. Instead, the car will whiz past the Red Planet by a much larger margin than expected and zoom off out toward the asteroid belt. T
[…]
Musk explained what went wrong with the attempted landing of the Falcon Heavy’s central core. The booster was trying to land on the floating autonomous barge Of Course I Still Love You when it suffered a “rapid, unscheduled disassembly,” to use SpaceX’s term for crashed and burned.

According to Musk, the booster had enough main fuel to make the landing, but it ran out of the triethylaluminum and triethylborane (TEA-TEB) fuel that is used to reignite the rocket engines, which are needed to control the rate of descent. Its central motor lit up, but the two other engines didn’t.

The result was that the booster came down too fast and off target. It hit the Atlantic ocean at about 300 MPH 100 metres from the barge, and disintegrated, damaging two of the sea vessel’s four thrusters, which are used to keep the ship in position.

Source: What did we say about Tesla’s self-driving tech? SpaceX Roadster skips Mars, steers to asteroids • The Register

Typical Tesla!