What is the Orion spacecraft's heat shield made out of?

[0:00] And for more on the science behind the cruise reentry to Earth, ABC News contributor and astrophysicist Hakeem O'Shea joins me now live. [0:08] Hakeem, thank you so much for your time today. But I want to start with what are the key things that you're watching for as as they prepare for to reenter the Earth's atmosphere tonight? [0:22] Thank you for having me, Alex. It's a joy to be on here again. You know, for me, it's all about safety. [0:27] It starts with safety. It ends with safety. And the key technology that's going to keep these astronauts safe are their heat shields. [0:34] If you could see what this craft experiences when it enters the atmosphere, you know, it's going to basically slam into the atmosphere. [0:43] So if you think about high divers, right, when they hit the water, the water behaves like a solid. [0:48] Well, you know, we think of air as being soft. Right. But when you're moving at 24,000, 25 miles per hour, 25,000 miles per hour, [0:56] it is anything but. And there's a lot of physics that's going on from the friction to the compression. [1:02] They're going to be surrounded by plasma. All that heat is going to ionize the air around them. [1:07] And those heat shields, all of that heat is going to build up. [1:10] And those heat shields are built to shed that heat energy so it doesn't go in the capsule. [1:15] It keeps them safe. And they splash down exactly as planned. [1:19] Well, and Hakeem, you mentioned those heat shields. What are Orion's heat shields made of that's able to withstand those temperatures? [1:29] Yeah. So really what you're thinking about is how do you dissipate energy as well as insulate? [1:35] So it's a multi-layered material. And the outer layer is designed to do what is called ablate. [1:41] It melts and it wears away. And as it just like when your skin, you sweat and that sweat evaporating takes away your heat energy. [1:51] In the same way, that surface melting takes that heat energy away. Right. [1:56] If you think about water boiling, once it starts boiling, the temperature does not rise anymore because instead of the energy going into heating the water, it goes into breaking those bonds. [2:09] So it's the exact same process. You can think of this heat shield as a material that sweats. Right. [2:14] It takes away the heat energy. And of course, you know, we're familiar with thermal insulators here on Earth. [2:20] They're in the walls of all of our homes. [2:22] So what you need is something to take the energy away. And also you need protection against the intense heat because the surface of that heat shield is going to reach 5000 degrees Fahrenheit. [2:34] You know, the surface of the sun is 10,000 degrees Fahrenheit. So that's a lot of heat. It's half as hot as the surface of the sun. [2:41] Yeah, that's that's that's a wild, wild stat there. [2:44] Well, and the other thing that I wanted to ask is so we know that Artemis one's heat shields, they experienced some unexpected damage during reentry. [2:51] It led to to cracking and detachment. So what adjustments did NASA make to ensure this crew's safety? [2:59] Yeah. So it's one of those cases where someone's like, I have a great idea. [3:03] You know, if we instead of going straight into the atmosphere, what if we skip off the atmosphere, shed some energy, then we could come in for the final approach at a lower speed. [3:17] So we won't have to dissipate as much heat. And we have a wider variety of choices in where we land. [3:23] Well, there was an unintended consequence. And that is, is that they had extreme heating and then extreme cooling and then back to extreme heating air went into the heat shield that created air pockets that then later expanded and broke off pieces. [3:37] So what they said is let's jettison, pun intended, that skip approach and let's go straight in because the heat shields, even though they had those problems, they still protected the capsule. [3:50] So what they now know is that they can come straight in, maybe try that maneuver sometime later with a different heat shield material, because, you know, retooling the heat shield for a completely new material. [4:02] There was no time for that. So they're taking the direct approach on this mission. [4:08] Well, and Hakeem, let's listen in to what's now like the live broadcast from NASA TV as the space agency prepares for the Artemis crew to splash down. Take a listen. [4:18] We will have a series of roll maneuvers. These are computer commanded that will roll the vehicle slightly to the left, then back to the right. [4:25] That will bleed off excess energy as we begin our peak period of velocity. [4:32] We expect to reach a maximum velocity of 24,661.21 miles per hour, equivalent to about Mach 33, 33 times the speed of sound shortly after we enter that blackout period. [4:47] Once we exit the blackout period, of course, we're in the denser regions of the Earth's atmosphere. [4:51] And then we get set up for the parachute deployment sequence. [4:57] First, the deployment of three forward bay cover chutes that will pull essentially the top forward bay cover off the very top of the integrity vehicle. [5:05] That will be followed by the deployment of drug chutes. [5:08] And then the final deployment of a series of three main parachutes at 7.04 and 44 seconds p.m. Central Time. [5:16] From that point on, it is about three minutes or so until splashdown, splashdown scheduled at 7.07 and 8 seconds p.m. Central Time at a gentle speed of 19 miles an hour. [5:30] So just to give you some perspective, at the time that we enter the Earth's atmosphere, we're traveling somewhere around Mach 32. [5:40] We will splashdown at a speed of about 19 miles an hour. [5:46] The g-forces that will build on the crew members inside Integrity will build to about 3.9 g's. [5:53] That is what is expected and what they have trained for and what the spacecraft is designed to support. [6:01] Hakeem, you were just listening in with me. [6:12] What did you make of what we just heard? [6:16] Well, I tell you, you know, it's really fascinating because these astronauts have been in zero g. [6:23] They have been weightless for all of these days. [6:25] And now, upon re-entry, at peak deceleration, they will feel four times their body weight. [6:32] They will, you know, so me, as a 200-pound man, I'd feel like I'm 800 pounds. [6:37] Now, I've ridden in the zero-gravity plane where on the ascent, you get to be twice your gravity. [6:43] That was weird. [6:44] Four times gravity? [6:45] That would be incredible. [6:47] But then also what the vehicle has to do to undergo such a deceleration from Mach 33, and one thing about moving faster than the speed of sound, and we're talking about energy dissipation and moving through the atmosphere, when you're moving slower than the speed of sound, the speed of sound is what is shorthand for the speed at which information and waves can travel through that medium. [7:09] So you're moving faster than information can move through that medium. [7:12] That means that the air molecules don't separate for you. [7:16] You're slamming into them. [7:18] So that is a lot of energy that's going to be dissipated in a short amount of time. [7:23] And then when they're moving subsonically, they deploy their parachutes and softly land in the ocean. [7:32] Well, and let's talk about, you know, the takeaways from this particular mission and how this potentially sets up Artemis III. [7:43] Right, right. [7:43] So what's going on here is a lot of systems have been tested, technological systems as well as the human body. [7:50] And there have been some small issues, like, for example, with the toilet, the human waste, you know, how you go with human waste, that's been tested. [7:59] You know, how they exercise, that's been tested. [8:02] The temperature control, the humidity controls, you know, the navigational system, setting up the radiation protection system and testing that out, right? [8:11] And we're talking about in close cramped quarters. [8:13] So you're also talking about a lot of the social dynamics that go on, staying on mission. [8:19] So all of these systems are being tested. [8:22] They didn't have to do landing. [8:23] As a matter of fact, this system wasn't even, you know, you couldn't land with the system that they went up in. [8:30] So now, you know, we've taken through Artemis I without humans. [8:35] We've done Artemis II. [8:37] We're going to do Artemis III and Artemis IV. [8:39] And ultimately have a permanent moon base. [8:43] So this is just a step along that journey, but it's been a very, very important one because it's the very first one that included real humans with their lives at risk. [8:53] Certainly. [8:54] Hakeem, I think you had to clear your throat just like I did just a minute ago and taking in all of what's happening right now. [9:00] Again, for our viewers that are watching, we have these live images of the crew inside that capsule as they're preparing for reentry. [9:09] All four of them were just now a little more than an hour or a little less, excuse me, than an hour and a half away from that expected splashdown right there off the coast of San Diego. [9:21] And look, Hakeem, we were talking about the physics behind, you know, all this technology just involved in the reentry and the calculations. [9:32] And this is something that it takes years to develop. [9:36] Yeah, yeah, it absolutely is. [9:38] You know, if you think about just your lunar injection burn, your translunar injection burn, right, the timing on that has to be just right, you know, for that major burn. [9:47] And you have a smaller corrective burn afterward, then you're looking at this free return trajectory where it's essentially like you throw it up there and then you let it fall back down to earth, right? [9:58] Like who would have imagined that in the 1950s, you know? [10:01] And then all of these life support systems and this autonomous vehicle, right? [10:07] We have way more cars on our streets and some people are like, there's no way I'm getting inside that thing now, you know, because there's no driver. [10:14] Now imagine you're placing your life in the hands of a spacecraft that is autonomous, right? [10:20] That system has been tested. [10:23] But again, I say it over and over again, these engineers are incredibly great at what they do. [10:29] These astronauts, you know, they're incredibly good at what they do. [10:32] They're incredibly courageous people. [10:34] This reentry into earth's atmosphere, again, they're placing their lives into the hands of the technology [10:40] and the technologists that have prepared these systems for them. [10:45] So if you think about a fighter pilot that has those mechanics on the aircraft carrier who they have to rely on, [10:52] in the very same way, these astronauts are placing their lives in the hands of a large team of engineers. [11:00] Multiple systems in coordination have to work properly and bring them safely back to earth. [11:05] Yeah, it's really a fascinating feat, all of this coming together just to make this mission happen. [11:10] Hakeem, hey, thank you so much for your time today. [11:13] Thank you for having me, Alex. [11:15] Of course, of course.