With the first three Starship launches, the FAA license required SpaceX conduct a mishap investigation with federal oversight if the rocket failed to reach its destination intact. The outcome of the last test flight—Starship's breakup over the Indian Ocean—triggered such an investigation by SpaceX. //

But this approach isn't congruent with SpaceX's roadmap for Starship development. SpaceX's iterative approach is rooted in test flights, where engineers learn what and what doesn't work, then try to quickly fix it and fly again. A crash, or two or three, is always possible, if not likely. The FAA is making an adjustment for this week's mission.

"As part of its request for license modification, SpaceX proposed three scenarios involving the Starship entry that would not require an investigation in the event of the loss of the vehicle," the FAA said in a statement.

Based on language in the code of federal regulations, the FAA has the option to approve these exceptions. The FAA accepted three possible outcomes for the upcoming Starship test flight that would not trigger what would likely be a months-long mishap investigation.

These exceptions include the failure of Starship's heat shield during reentry, if the ship's flap system is unable to provide sufficient control under high dynamic pressure, and the failure of the Raptor engine system during the landing burn. If one of these scenarios occurs, the FAA will not require a mishap investigation, provided there was no serious injury or fatality to anyone on the ground, no damage to unrelated property, and no debris outside designated hazard areas.

This change is quite significant for the FAA and SpaceX. It shows that federal regulators, suffering from staffing and funding shortages, are making moves to try and keep up with SpaceX's rapid, and often ever-changing, development of Starship.

"If a different anomaly occurs with the Starship vehicle, an investigation may be warranted, as well as if an anomaly occurs with the Super Heavy booster rocket," the FAA said. //

Bannerdog Ars Praetorian
8y
410
Only SpaceX can say, "not all of our rockets crash".
Hopefully someday, "none of our rockets crash*". //

taxythingy Ars Centurion
7y
397
Subscriptor

uhuznaa said:
Just using somewhat contaminated preburner exhaust for pressurization the oxygen tanks (hot oxygen with some steam and CO2 in it) would be much simpler and lighter though than having pure propellant go through heat exchangers first. Best part is no part and so on. It would be a quite typical approach for them.

At least all the valve and filter clogging in the last flight is hard to explain otherwise, where was all the ice coming from? Usually filters are just for protecting the engines (especially the pumps) from ingesting random debris ending up in the tanks but to have the filters of several engines clogged by ice there needs to be quite a lot of that. It's a mystery to me where all this ice came from. If you use clean oxygen for pressurization and purge the tanks with dry nitrogen before tanking there just should be no ice anywhere.

(They could tap hot methane off the nozzle cooling but there is no source for clean hot oxygen gas except using a dedicated heat exchanger just for that, and it seems the ice was in the oxygen tanks.)

The oxygen is super cooled to improve density and is getting close to the triple point (within 20K) at tank pressure, where solids can form. The general understanding is that solid O2 forms, probably at the liquid gas interface (boil off is cooling it further) and that then settles to the tank bottom as a slush. This is more likely to occur after the main burn when the tank is near empty.

On relight, that has to be filtered out, else it will either block the injectors or otherwise run rough.

The Shuttle had filters, but that was more for debris, if I remember correctly.