12
$\begingroup$

Starman was in a 6 hour holding orbit before the injection burn to Mars (Assuming that happens at the 6 hour mark). This was done to test the capability to put a satellite directly in GEO orbit. Did Starman actually orbit the Earth multiple times in that period of time?

$\endgroup$
5
$\begingroup$

As I could understand, there were two additional burns after the orbit was achieved. One, in the first orbit, that raised the Apogee to 7000 Km. The other was, probably, done in the Perigee again, and was the one that would put Starman in the Heliocentric orbit that stretches from Earth's to Mars' orbits. I think they opted to separate into two burns so they could take advantage of the Oberth Effect.
https://en.wikipedia.org/wiki/Oberth_effect

I would, then, say that it has completed only (roughly) two orbits around the Earth. The 6-hour wait was necessary due to the higher orbit period after the first burn.

|improve this answer|||||
$\endgroup$
  • 7
    $\begingroup$ An orbit with LEO periapsis and a 7000 km altitude apoapsis would have a half-period of only about 85 minutes. Could you clarify this estimate a bit more? $\endgroup$ – uhoh Feb 7 '18 at 5:47
  • 1
    $\begingroup$ Great! I actually did not make the calculations, my bad. I'll have to rethink this.... =D $\endgroup$ – Sócrates Costa Feb 7 '18 at 13:21
  • 1
    $\begingroup$ That's what I like about Space Exploration SE, it keeps me thinking! $\endgroup$ – uhoh Feb 7 '18 at 13:24
  • 2
    $\begingroup$ The 6 hour wait was a demonstration, it wasn't required in any way. It probably make the whole thing more complex, and lost capacity with time actually. I'm sure the last burn would be done near perigee. $\endgroup$ – PearsonArtPhoto Feb 7 '18 at 14:26
  • 4
    $\begingroup$ @SócratesCosta The 6 hours orbiting was to show that the second stage can survive the heightened radiation of the Van Allen belts. That's one of several abilities the USA's DoD is looking for. $\endgroup$ – pepoluan Feb 9 '18 at 19:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.