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NASA Video Shows What It's Like To Reenter the Earth's Atmosphere
astroengine writes: In a mesmerizing new video released by NASA, the Dec. 5 reentry of the Orion test space vehicle is chronicled — and it's a phenomenal 10-minute ride from fiery reentry to sudden splashdown into the Pacific Ocean. (YouTube Link.)
You can't really appreciate what NASA does until you build your own rocket, load it up with little green men, and crash it dozens of times while you try to learn how to orbit. Kerbal Space Program taught me how impressive this achievement really is.
That time that it takes for the main chutes to fully open has got to be a real nailbiter.
For those like me, who just watched the video and didn't understand the point of view 'til quite late on, the camera is pointing back along the direction of flight.
Also, for some reason the video has strange out-of-focus side-pieces that are distracting and annoying. The view itself is gorgeous and amazing.
Blasphemy is a human right. Blasphemophobia kills.
That time that it takes for the main chutes to fully open has got to be a real nailbiter.
I could be by design... http://en.wikipedia.org/wiki/S...
Nice! (From your link): A slider is a small rectangular piece of fabric with a grommet near each corner used to control the deployment of a "ram-air" parachute. A ram-air parachute has a tendency to open very rapidly. At high velocities, the opening shock from such a rapid deployment can cause damage to the canopy or injury to the jumper. The slider was developed as a way of mitigating this. During deployment, the slider slides down from the canopy to just above the risers. It is slowed by air resistance as it descends and reduces the rate at which the lines can spread and therefore the speed at which the canopy can open and inflate.[1] This invention solved the rapid deployment problem with ram-air designs. Sliders also reduce the chance of the lines twisting to cause a malfunction.
Sliders are not utilized on these parachutes. A reefing line, basically a circular cord holding the skirt of the parachute closed, is cut after a predetermined delay using small timed pyrotechnic cutting charges. These are designed to keep the parachute from overpressurizing and blowing out during high-velocity opening. FYI - I was a parachute & survival equipment specialist in the USAF.
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unlike a few Shuttle cockpit shots. Or previously few seconds clip from a Gemini re-entry that's replayed zillion times like the Saturn interstage separation between first and second stages. My question has Elon released any such footage?
mfwright@batnet.com
The edge of space has too thin of an atmosphere for controlling anything. How can you stop going 32.000MPH slowly, without bouncing off like a pebble across water? This was the main concern about re-entry as I recall. Even if you could slow down slowly you would drop like a lead weight without a thicker atmosphere to slow the fall. So they quickly get into the controllable area ASAP.
You don't really "bounce off the atmosphere" if you miss your angle. What happens is that you don't lose enough speed to deorbit. From low Earth orbit, you'll hit the atmosphere again after one more go around the big blue marble.
The problem with Apollo was that the command module had nothing like the supplies of consumables that would be needed for another spin around the Earth, and it was moving substantially faster than LEO speeds - it wouldn't be reentering in another ninety minutes. And the Apollo CM had a slightly asymmetric distribution of mass, allowing it to generate lift and steer itself (Apollo 11 extended its reentry path to avoid storms, e.g.).
Space Shuttle attempted to do what you describe, coming as close to that ideal as reentry dynamics would allow. It still required a 40-degree angle of attack during the hot part of deceleration. The final approach may look airliner-like, but the sink rate was something like seven times that of a Boeing, a requirement of the delta-wing design, which in turn was imposed by the need to reenter without stripping off the wings.
The Orion capsule may look like a throwback to the Sixties, but it's the most tolerant, safest design of all.
This isn't anything new. It's a lot safer than the first part of the trip, the part where huge quantities of highly reactive stuff is going 'boom' constantly somewhere below you.
Everybody, please read OP's comment and understand that it provides us a valuable learning opportunity.
Suppose you read a popular press article about a complex subject (like space flight) and all the experts in the field have concluded that it should or has to be done one way, or one of a few ways. Having read a summary and maybe spent 5 minutes on Wikpedia still hasn't revealed why it's done this way. The two most important things to do now are to admit that you don't know, and realize that that's perfectly okay because admitting you don't know is the first step on the path to knowledge. Ask a question with non-hostile phrasing; This will invite people to provide helpful, explanatory responses and you will, as the saying goes, come off smelling like roses.
Or you can go OP's route, and we'll all laugh at your dumb ass for being stupid enough to think that spending 5 minutes reading Wikipedia makes you smarter than all the experts who've ever worked on rocketry. Then we'll put the Cone of Shame on you and make you sit in the corner while we chalk up yet another mark in the "true" column for the Dunning-Kruger hypothesis. At some point, we'll probably idly speculate whether your attitude is causative or symptomatic of your total inability to get laid and decide the answer is "yes."
They are "doing it right", there's just no way to do it the way you seem to think it should be done because of the speeds involved and the physics of orbiting.
Low Earth Orbit is only achievable with a speed of roughly 7.8 km/s (17,450 mph, 28,080 kph). Compare that to our regular "smooth controlled flight just like regular flight", with airliners topping roughly 600 mph (1,000 kph), and the fastest air-breathing manned aircraft ever made (the magnificent SR-71) only approaching 2,200 mph (3,500 kph).
The mechanics of orbiting says that to keep a stable orbit you keep a stable speed; if you increase speed you go to a higher orbit, and if you decrease speed you go to a lower orbit. So to get out of orbit we need to slow down.
So you're starting re-entry from a speed roughly ten times faster than a M-16 bullet - at these speeds any interaction with any kind of atmosphere is going to create "major high temperatures", but the physics say that you can't slow down without lowering your orbit and hence entering the atmosphere.
So we're in a bit of a bind here; we're orbiting at 28,000 kph, and we need to slow down to about a tenth of that to even have a chance of "smooth controlled flight" - but as soon as we slow down, our orbit lowers and we hit atmosphere, creating "major high temperatures" because of our speeds.
It should also be noted that it took the better part (70-90% or so) of our launchpad mass to get us up to this speed, and we simply do not have enough fuel to do much of any brake thrusting - the Tsiolkovsky rocket equation is a harsh mistress indeed.
So you see, it's not really that they're "doing it wrong", it's that you don't understand the problem. To be up there in the first place means you have to go really, really fast, and that means re-entry cannot be done "slowly, [...] gliding down gracefully", because as soon as you start to slow down your orbit decays and you start re-entry.
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