Starting an engine in a vacuum under microgravity conditions is really difficult to test on Earth. Why isn't the first stage test being used to gather data for this?
$\begingroup$
$\endgroup$
1
-
$\begingroup$ I have heard speculation on this topic: specifically, the test Starship does not have the hardware/capability to settle the fuel to the bottom of the tank in microgravity (related to header tank?). Later test articles are said to have this function, however SpaceX didn't feel like retrofitting this newer feature on a rather old (at this point) Starship $\endgroup$– DragongeekApr 19 at 12:14
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
1
For the upper stage, success or failure of such a test would have a relatively large effect on landing location and a failed test could potentially result in damage or loss of control, making it impossible to do the intended reentry testing. And the first stage will be lighting its engines in microgravity conditions, for the boostback burn, so there would be little to learn by doing it on the upper stage as well.
answered Apr 19 at 23:00
-
$\begingroup$ Just compare the hazard zone for this flight (which is already big) to the absolutely ginormous ones for flights two and three (with the Starships without heat shield or flaps), and then imagine you had to do this for all the eventualities where the engines don't relight, they relight and can't be shut down, the partially relight, they relight and shut down early, they relight, explode, and damage the heat shield, they relight, explode, and damage the flaps, or the entire ship explodes. $\endgroup$ Apr 20 at 21:07