After accomplishing their primary mission, which is a key distinction. If you blow up on landing that just means you lose your reuse discount on a future flight.
Yeah, which is why they're making Starship better than the Falcon 9 in being able to land safely even when things go wrong (i.e. Starship can throttle down enough to hover). They're still in the early prototyping stages. You can't judge potential long-term reliability based solely on what we've seen so far.
It's totally different because only the government is allowed second chances! Everyone else has to get it right the first time. Especially if they're competing with <insert defense/aerospace contractors here>!
Never attempted what? Relight an engine? Engines are routinely re-lit, especially on upper stages, yet Space-X gets it wrong with regularity. The Russians and Arianespace do it just fine.
I'm sorry, what? SpaceX are the undisputed champions of re-lighting engines. They've landed orbital rockets 73+ times, each of which involves multiple engine re-lights while falling through the atmosphere. Let alone gets it wrong "with regularity" — the Falcon 9 Block 5 is a remarkably reliable rocket.
Anyway, landing Starship involves a bunch of things never before attempted: landing a fully-reusable second stage, landing a vehicle of this size, relighting and running engines during the belly-flop-and-flip maneuver, and flying and relighting full-flow staged-combustion engines. Probably some other firsts too.
Today's crash was due to failure of one engine to restart. Briz and Fregat Russian upper stages are routinely restarted, with ~ 98 % success, same with Ariane EPS and Chinese Yuanzheng. It's doable, just not for Space-X.
Briz and Fregat start much smaller - 20 kN - engines with no time constraints, while Starship re-lights 2200 kN engine and rocket immediately does rotation by 90+ degrees, and time is of essence.
Saying SpaceX gets it wrong regularly is LITERALLY false. SpaceX Falcon 9 is fully qualified for all DoD Orbits and has reached highest qualification for NASA Scientific Missions and Human mission for. All require demonstration of reliably relight with incredibly high reliability.
In fact, in over 100 flights, SpaceX did not have a single failure of a Second Stage engine not starting or not re-lighting. This is unlike Arianespace who just had a failure when they tried to start an engine on one of their upper stages.
Outside of that Merlin is easily the engine that can be re-lit more then any other on the planet and its not close.
This however is a non-commercial prototype, where they are testing new technologies. Its a completely new engine of a type that has never flown before and is not finished developing. The vehicle has been newly designed and it does things no other vehicle has done before in a way no other vehicle has done before.
You honestly just sound like an incredibly petty hater. I can grantee you that Russia and Europe have plenty of issues with engine starting on their development engine.
NASA and the USSR did many powered rocket landings, actually. NASA even had a program for reusable first stages via powered landings that was scrapped because automatic guidance wasn't feasible yet.
Failing to restart an engine in a retrograde trajectory. A difficult task that both the Soviets and NASA (and Arianespace and the Chinese) had issues with, but worked out.
It's very difficult because of the turbulent airflow in an engine bell pointed against the airspeed vector. Despite this, many rocket engines can do it reliably.
There are a lot of reasons for which an engine would fail to start in such a scenario. They all boil down to the turbulent airflow and high pressure in the nozzle inhibiting the ignition process.
How exactly you decide to fix it depends on many things. It's impossible to tell. But they are all downstream of the same failure, which is overcoming the high pressure and turbulent flow.
>At an altitude of about 1.5 kilometers (5,000 feet), the lander activated its three retro-engines and was released from the parachute. The lander then immediately used retrorockets to slow and control its descent, with a soft landing on the surface of Mars.
