That's something that's been irking me whenever I watch the booster and now the ship, come crashing down at triple digit MPH speeds then watching it re-light the engines at the now front (aft end of the vehicle but going head first), what with a bunch of non-aerodynamic surfaces there. I am obviously not qualified to assess this, but I wouldn't bet on those engines being reusable more than 2, max 3 times each.
Then again, I wouldn't know how to solve this better -- if you say, have a cover protecting the engines before re-lighting, you're not shedding speed any better than without it, and after re-entry and when the speeds are relatively modest (only, say, 400mph 2-3km up vs 4000mph at 100+km) the air itself doesn't do anything to the engines anyway.
The booster has flaps that help it shed speed, but the Starship's flaps are very different, aren't they? And it's not exactly the kind of a flying brick that Space Shuttle was, either -- having it coast longer before it flips to be caught by Mechazilla, isn't a solution then...
What they do with Falcon 9 is insane as well - they have a portable heatshield for re-entry. That is, the heat shield is the exhaust of the engines. Which is absolutely glorious, not only do you brake, but you shield the rest of the ship using the exhaust as well, as a blowtorch burning to the atmosphere.
Taking an engine off and putting a replacement on is a fast process. Iirc booster gets all its engines in a day or two. Not quite like changing a lightbulb but I think it’s a fast process.
Then again, I wouldn't know how to solve this better -- if you say, have a cover protecting the engines before re-lighting, you're not shedding speed any better than without it, and after re-entry and when the speeds are relatively modest (only, say, 400mph 2-3km up vs 4000mph at 100+km) the air itself doesn't do anything to the engines anyway.
The booster has flaps that help it shed speed, but the Starship's flaps are very different, aren't they? And it's not exactly the kind of a flying brick that Space Shuttle was, either -- having it coast longer before it flips to be caught by Mechazilla, isn't a solution then...
Just ramblings of an amateur :B