Lockheed Martin’s Orion space capsule is on its way to San Diego after a flawless re-entry and splashdown capped an almost equally successful shakedown mission around the moon. The ship, which will ultimately be used to carry astronauts to the moon and perhaps Mars, hit the surface of the Pacific off Baja Mexico at 12:40 p.m. ET Sunday. It then spent about six hours bobbing in the ocean while NASA scientists gathered yet more data from the finale of the 25.5-day mission. The capsule carried instrumented mannequins to aid in assessing what the future human occupants can expect on their missions.
The spacecraft used a new “skip entry” descent that allowed NASA to more precisely set the re-entry trajectory of the capsule. Instead of just plowing into the atmosphere, the capsule hit the edge of it for initial deceleration and then re-entered for the final plunge. The capsule also had a newly designed heat shield and it held up. The temperature inside the capsule rose from 64 to 71 degrees Fahrenheit while the plasma cloud formed by the friction of re-entry hit 5,000 degrees. After its prolonged dunk in the ocean, the capsule was hauled aboard the USS Portland for the trip to San Diego.
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.
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.
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).
They lacked the computational power to have confidence in guidance for a skip entry. Certainly not the case now.
Wow, a splashdown! Just like the old days.