Reentry basics

1:07:49That would be great. Okay, so the final part of our segment, I want to talk about re-entry. >> Yes. >> Which is going to be happening on Friday around 5:00 p.m. I believe is when they're going to be re-entering the Earth's atmosphere and landing somewhere right off the coast of San Diego. >> And that's going to be Friday, April 10th. >> Yes. >> Yes. >> Yeah. Okay. So atmospheric re-entry, you're approaching the Earth's atmosphere and all of that energy that was put into that translunar injection burn has to get shed. >> Right. >> Right? Conservation of energy. >> Right. >> In space >> There's nothing. >> that energy hasn't gone anywhere. It's just in the motion, right? Um, sure, when you're at the moon, you're going a

1:08:29bit slower, but that's because you have so much gravitational potential energy. By the time they're falling and currently as we as we record this episode, they are falling from the moon, right? All the way from the moon back here by the time they enter our Earth's atmosphere, they're going to have a velocity, a speed of 40,000 km/h. Almost the same as the velocity that they left the >> Right. Right. And it's funny, I mean, the space is a vacuum, right? So there's There's no way to dissipate. >> Yeah, it's just in the motion and >> of that motion, all of that kinetic energy has to go somewhere. And so, what we want to do fundamentally is dump all

1:09:12of that kinetic energy as heat >> Mhm. >> into the atmosphere. >> Right. >> That's That's the equation that we're doing. Before is kinetic energy and, you know, whatever the temperature >> Which Which just to be clear for those who might means just movement or motion. Like when you say kinetic energy >> Yes. >> Can you just be a little >> Yes. Yeah. Yeah. Yeah. Yeah. Fair Fair enough. Um when I say kinetic energy, I mean this thing, the Orion capsule up here, this little triangle pyramid part >> Yes. >> is moving at 40,000 km/h. 1/2 mv squared, that's the kinetic energy of this guy just on the motion of the thing. >> Mhm. >> We want to slow it down so that it doesn't slam into the Earth like a

1:09:52meteorite. >> Okay? >> Right. >> And in order to do that, all of that energy from the motion has to go somewhere. Right. So, the model is always we dissipate it as heat in the atmosphere. >> Mhm. >> Okay? We got to be careful though, okay? There's got to be a method to this madness. >> Right. >> And this is where the re-entry procedure comes in. So, in the next segment we're going to talk about how long does that take?