What is the difference between re-entry from the Moon and Re-entry from low Earth orbit?

  • 1
    $\begingroup$ 3 km/s, and a different thermal protection system. $\endgroup$ Apr 23, 2014 at 13:34

1 Answer 1


I suspect you're asking about low earth orbit versus a lunar return trajectory. (Strictly speaking, that lunar return trajectory was an orbit). The difference between the two is velocity. The Shuttle reentered about about 7.7 kilometers per second. The Apollo spacecraft, at about 11 kilometers/second.

That extra 3.3 kilometers per second doesn't sound like much, but it is. Since kinetic energy is proportional to the square of velocity, that means that energy per unit mass for a lunar return is more than double that of a reentry from low earth orbit. That doubling in energy in turn mandates drastically different protection against the temperatures that build up due to reentry.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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