December 2022
Are there more details about the “skip entry” descent? As I recall, Apollo used the same technique when returning from the moon. The initial plunge into the atmosphere was at an angle such that the Apollo capsule would skip off the thicker layers like a stone on a pond. This bled off some of the initial 25,000 MPH reentry speed. It would then hit the atmosphere at a steeper angle for final descrent. I’d like to hear more about how this new technique differs from the Apollo descent profile.
Another point - the heating during reentry is mostly due to compression, not friction. The atmosphere can’t get out of the way of the capsule fast enough. The compression of the air causes abdiabatic heating of several thousands of degrees.
1 reply
December 2022
▶ KirkW
My understanding is that Apollo could use a skip entry, but that the entry they actually used wasn’t. What it did use in practice was a series of rolls to shallow and steepen the descent, but it stayed within the atmosphere the whole time. I’m not sure why they apparently didn’t use a true skip entry (where after the initial atmospheric entry, they actually climb away from the atmosphere and then reenter).
Assuming my understanding of the actual entry profile used by the Apollo missions is correct, I think what was meant was that Orion used a skip entry for the first time on a returning lunar mission.
1 reply
December 2022
They lacked the computational power to have confidence in guidance for a skip entry. Certainly not the case now.
1 reply
December 2022
▶ gmbfly98
Looks like you are correct. Here’s a contemporaneous video of Apollo re-entry. Even though they repeatedly call it a “skip” maneuver, they do say that the Apollo capsule doesn’t leave the atmosphere (defined as 400,000’, or 75 miles in this video).
https://www.youtube.com/watch?v=MTKHqfloB7Q
December 2022
Wow, a splashdown! Just like the old days.
(Couldn’t resist)
