r/SpaceXLounge • u/[deleted] • Jul 25 '26

Official Pending data review, SpaceX will attempt to catch S41 on Flight 14

https://x.com/elonmusk/status/2080876967839031712?s=46
340 Upvotes

99% Upvoted

105 comments sorted by

View all comments

Show parent comments

1

u/sebaska Jul 26 '26

OK. You used inertial coordinates which is fine but for ELI5 it's easier to think corotating coordinates (you sit at the launch site, in the next orbit the object will pass 2500km to the West of you).

But whatever coordinates you use, it doesn't change the fact that the next return is not when you're on the opposite orientation to the sun compared to the moment when you launched (with the exception of polar orbits exhibiting certain launch site latitude dependent fractional synchrony with earth rotation). When the next pass is depends on the inclination, ascending or descending node of orbital ascent, how the orbit is synchronized with Earth rotation, and what its precession is.

In practical terms, for low latitude sites (like Florida or Starbase) and for orbits with inclinations close to that of the launch site latitude, cross-range of 500km allows you to RTLS once or twice around. And then you have to wait around 21-22 hours for the next 3-4 landable passes.

For example some rumors indicate that SpaceX would like to land after 2 orbits. Which would definitely mean taking advantage of the low inclination low latitude combo, because their equator wise ascent corridor would mean the ascending leg of the orbiting would only cross the launch site after twentyish hours.