NASA astronaut rates 10 space movies based on how realistic they are

• Hollywood loves its space movies, but how well do they nail the actual science?
  
• NASA astronaut Garrett Reisman, former director of space operations at SpaceX, rates 10 iconic scenes from space movies based on how realistic they are.
  
• See how the facts in your favorite space movies hold up, from "Gravity" and "Interstellar" to "Star Wars" and "The Martian."

Following is a transcript of the video.

Han Solo: Let's blow this thing and go home!

Garrett Reisman: "Pwsh!" Hi, I'm Garrett Reisman, former NASA astronaut. And today we're gonna look at some popular movie clips, and I'll try to use my experience as a former director of space operations at SpaceX and current professor at University of Southern California, USC, and give you a rating on how realistic it is.

"Gravity" (2013)

Ryan Stone: No, no, no, no! Gotcha.

Matt Kowalski: You have to let me go, or we both die.

Stone: I'm not letting you go. We're fine!

Kowalski: No.

Stone: No!

Garrett: Oh, my goodness. Oh. Yeah, that was bogus. [laughs] I really like this movie, despite the fact that the science, totally wrong. This movie takes great liberties and completely blows off the basic laws of physics.

Kowalski: Man down!

Stone: Copy. Houston.

Garrett: The movie deals with space debris, and that's what causes the calamity that they then have to fight the rest of the movie. This is a real problem, and it's getting worse. So, some of the stuff is natural, but the vast bulk of the flux, the density of the stuff whizzing around the Earth, is created by humans. It's stuff that we shot up into space, and we didn't clean up our own mess. When I was up there, several times I heard debris hit the space station. There's certain things in the movie about how they show the debris that's not accurate. You can see it coming in the movie. They see this, like, cloud of debris coming from thousands of kilometers away. That's bogus, OK? This stuff is traveling an order of magnitude like 10 times faster than a rifle bullet. You can't look at a shooting range and see a rifle bullet flying around from thousands of kilometers away. You're not gonna see this stuff coming. And the other thing about this that's completely unrealistic: George Clooney is flying on by, and Sandra Bullock reaches and grabs his tether and grabs onto him. That would be hard. As he's flying on by, he would, with his momentum, try to carry her away and pull her away from the space station, and she would have to resist that and stop him, which she does. Yay, Sandra Bullock. You have saved the day. Well done. End of story. It should end right there. There's no gravity, right, that's pulling him away. It's not like she's holding him, like, over a cliff or something. He is not pulling her off the space station anymore. The work is done. And once she has stopped his motion and he's just sitting there, and she's holding on to the other end of the tether, all she has to do is go like this with her littlest pinky. "Boop!" And pull him, and he would be going right back to the space station, and they'd be having a nice lunch together. He says, "You have to let me go." Why? Why does she have to let him go? And you've got a firm grip on George Clooney. You do not let go. OK? No matter what the laws of physics say, you hold on.

Rating: 2/10

"The Martian" (2015)

Mark Watney: On my way, commander.

Garrett: This whole idea about puncturing your glove to fly like Iron Man and be rescued by your spaceship. Yeah, not so much. We have a jet pack that we wear when we do spacewalks on the space station. We needed to have something to do if you became untethered and started floating off and you're gonna become lost in space during a spacewalk. That's why we added these jet packs. It's just nitrogen. And it's just little puffs, "psh, psh, psh," of nitrogen that come out of those little jets is enough to let you fly back to the space station and stop you from being lost in space. Now, first of all, you would need a spacesuit pressurized really, really high to get enough pressure to actually get the kind of thrust that he gets. In reality, it's gonna be a tiny little gentle push. There's not gonna be a "shh!" It's gonna be a "pew, pew, pew, pew." You know, come on. So that's the first thing that's wrong. But if you do have this big rocket engine coming outta your hand, and you're trying to control yourself, now you've gotta put that thrust through your center of gravity. So you gotta hold it very, very precisely, and any kind of motion away from the proper direction is gonna cause you to start tumbling out of control. You're gonna be like, if you take a balloon and blow it up and then just release it and it goes "pbbt" all over the place, no way you're gonna be, like, "zhhh," flying back where you wanna go. So, bogus, big-time bogus on that. The rest of the movie was up, like, a nine. The rest of the movie was really, really good.

Rating: 3/10

"Star Wars" (1977)

Solo: You're all clear, kid. Now let's blow this thing and go home.

Garrett: The scene in "Star Wars" where Luke Skywalker uses the force and destroys the Death Star by attacking its one hidden weakness. So, a couple things pop out right away. One is, you know, what's with the orange ski goggles on Luke in the middle of black space? I mean, really, you need that? And then, finally, like, Han Solo's wearing this earpiece with that microphone thing. It looks like he's a telemarketer. He looks like he's trying to sell you some insurance or something. But the big thing is they blow up the Death Star, right, which is awesome, and it goes "pwsh!" Now, that wouldn't happen. I mean, you're not gonna hear anything because sound needs a medium to propagate through. So right now, you're hearing me talk because as vibrations go on in my throat and air goes through that and the air molecules vibrate, they vibrate other air molecules, and because we have air in this room, it reaches the microphone and causes vibrations on the microphone. And then you hear that. If there's no air here, But other than that, you wouldn't be able to hear me. The thing is that if you're watching a movie and you see a big explosion and it's silent, it doesn't feel right to the audience. So I understand why movie editors and special-effects guys put the sound in, but it's bogus. You can see explosions, and there can be fire, even in the vacuum of space. You actually need three things. You need spark. You need fuel. And then you need oxygen for it to combust. Then you will see flame, you will see fire, even in the vacuum of space. You won't hear anything, but you'll see it. So that is plausible.

Rating: 5/10

"Interstellar" (2014)

Garrett: That McConaughey guy? He looks just like me, huh? So, I'd say, obviously, the casting people know what they're doing.

Cooper: TARS?

TARS: Roger that.

Cooper: Don't you get it yet, TARS? That's why I'm here. I'm gonna find a way to tell Murph.

TARS: How, Cooper?

Cooper: The watch. The watch.

Garrett: Wow, so that was pretty trippy, huh? If I remember right from the movie, he's inside a black hole at this point where the forces of gravity are so strong that not even light can escape. Recently, we got our first picture of a black hole. Really, what's around the black hole, because once light goes into the event horizon, the circle around the black hole, nothing comes out. But inside the black hole, nobody knows what happens inside there. Nothing ever comes back. If a person went inside a black hole, what would it really be like? Who knows? But you do see the light bending in there, and it is true that light will bend when it's exposed to very strong gravitational fields. A lot of the stuff that they did in this movie, they tried to be as realistic as possible, but I do have a problem with... there's this bookshelf tesseract thing. So, some advanced civilization created this tesseract where you go into this thing and it's, like, lined with books on the shelf, and by pulling the books off the shelf, you could see into other dimensions and you could communicate to people in those other dimensions in a very, very roundabout, incredibly complicated way. If you're a super-advanced alien intelligence that can build a bookshelf tesseract thing to go across dimensions, why can't you put in a phone? Or at least put in, like, a whiteboard, right? With a dry-erase marker that you could just spell, like, "Hey! Stay away from the black hole!" You know, whatever, and send a message that way. Why do you have to get so complicated? But other than that, they got a lot of stuff right, especially about the relativistic effects in the movie.

Rating: 8/10

"2001: A Space Odyssey" (1968)

Garrett: This is one of my all-time favorite space films. And what's really amazing about it is how realistic it is considering they filmed all of this before Apollo 11, before we landed men on the moon. And the science in the movie holds up tremendously well. The one thing that's missing there, and in the opening scene there, is the atmosphere. You just see the blue Earth and then suddenly the black space. In reality, when you look at the Earth from space, there's a thin blue line that separates the sunlit Earth from the blackness of space. So, you might be asking yourself, why is the space station spinning and why is it constructed as a big wheel? What you're doing is you're creating inertial forces that simulate gravity and have the same effect. Because the absence of gravity causes some problems to the human body. It causes, for example, some bone loss. Now, you're up in space, and you're floating around like a fish, and the bones are like, I guess I don't need to make any more bone. Your muscles, especially in your legs, start to atrophy 'cause you're not using your legs anymore. You're not walking. So all kinds of, like, funky and not-so-good things happen to your body in space, so we fight it. We fight it hard, and mostly by working out. We have to do it about two hours a day every day. But, hey, what if we can create artificial gravity? Then we wouldn't have to do any of this, and we wouldn't have any of these problems. That's the idea behind the spinning spaceship. The best way I can explain that is they had these old amusement park rides that were like a big washing machine. You get in, and it starts spinning, and it throws you up against the wall. And then the floor drops out, and you don't fall because you're being pushed back against a wall by a pseudo force we call centrifugal force. That's what's happening here in this space station. By spinning like that, you can create centrifugal force that acts and feels like artificial gravity. If you're creating artificial gravity with a small radius, like those rides in amusement park that make you go up against the wall, you can handle that spinning for a couple minutes. You don't want to be spending months in there, right? You need to avoid having the radius too small that you get what's called Coriolis effects that makes you kind of dizzy. You don't want that. You also need to be spinning fast enough so that if you walk the opposite direction, you don't start floating. So you have to have a rim speed that's typically about 6 meters per second, which is bigger than your average person walks. So, a lot of times in the movies, either it's not long enough or it's spinning too slow for it to really do its job. Does "2001" get it right? Yes, it does. If you look at that thing and you time the rate of the rotation and you try to estimate how big it is, the radius is about 150 meters, and it's spinning at about 1 1/2 rpm. That's enough to get you almost half a G. So almost half the gravity that you feel on Earth, which is probably good enough. So that's not bad. If those numbers are accurate. Which, I kinda made it up, so, you know. But I think we're close.

Rating: 9/10

"Guardians of the Galaxy" (2014)

Rocket: Quill, don't be ridiculous. Get back into your pod! You'll die in seconds!

Garrett: Hey, look, any movie with a talking raccoon is OK in my book. Oh, boy. [laughs] OK. First of all, it's great that he's got this mask on so he can breathe in space, but what about the rest of his body? The rest of your body is gonna be in really, really bad shape. The fluids inside your tissues is gonna vaporize, and so basically, your blood is gonna boil, all the water in your tissue is gonna turn into gas. He takes off his helmet to try to save his friend there, somehow holds his breath. Now, it's true that you can survive for very brief periods of time while exposed to a vacuum. It has been done. There's been accidents on Earth in vacuum chambers, and if you get quickly back down to regular pressure, you're gonna be OK. But there's a couple things you worry about. The first thing you have to worry about: barotrauma. So, what that means is that there's gas inside your body, in your lungs, in your sinuses, and that's gonna start expanding once you get exposed to a vacuum, 'cause now, instead of having the outside air pressure to work against, now there's nothing out here. It's gonna want to blow up like a balloon. Then you worry about decompression sickness, where all the nitrogen comes out of the solution in your blood, what scuba divers can get when they spend too much time at depth and come up too quickly. They call it "the bends" 'cause you bend over in pain at all your joints where the bubbles build up. So all that would happen to Star-Lord even before he takes off his mask. Having said that, did I mention that this movie has a talking raccoon? You're worried about the helmet? I mean, it's got a talking raccoon.

Rating: 2.5/10

"Total Recall" (1990)

Garrett: True story, I use this clip in my class here at USC when I was teaching this subject about what happens if you do get exposed to vacuum, and I tell people we actually have a test subject that volunteered, and at NASA we did an experiment, and we have video of that experiment, and here it is. And I show that clip, and they get a good laugh out of it. 'Cause, no, that's not really terribly accurate. What would happen if you're exposed to space and were not adequately protected, and that is when parts of your body, parts of your tissues, the liquid vaporizes, turns into a gas and you puff up like a balloon. Presumably, that would happen around your face as well, but it wouldn't look exactly like that. That's a little Hollywood magic right there. Another thing about this clip is that he hits a rock and the visor shatters, and you hear it shatter like it's glass. Most spacesuit helmets are made out of polycarbonate, which is much tougher. It wouldn't shatter quite like that. You can break your space helmet, and so tumbling down a surface on Mars and whacking your head into a rock is not recommended.

Rating: 5/10

"Spaceballs" (1987)

Barf: No, we're losing power!

Starr: Why? Barf: 'Cause we're outta gas!

Starr: OK, we'll have to set her down. Prepare for an emergency landing.

Garrett: I can't believe you actually want me to comment on the scientific realism of "Spaceballs." They're flying around space in a Winnebago with a dogman as your second in command, and, really, you want me to talk about whether or not it violates the laws of physics. Where do I start? First issue is if you're traveling in between planets, even between solar systems in the future, so, once you're on your trajectory, you're not burning your engines anymore. For example, when we went to the moon, we got into Earth orbit, we lit the engines up to get enough velocity to escape Earth orbit, and get on a trajectory going towards the moon. But that only lasted minutes. And then, once we had that velocity and we were heading in the right direction at the right speed, we shut the engines down, and you coast. So, if you run out of gas, you don't fall out of the sky. [laughs] You're going to continue coasting in the same direction and the same trajectory you had before. But, again, you know, it's a Winnebago. [laughs] So what do you want me to tell you? Anyway, if you can accept all that and you run out of fuel, now you fall, which is wrong. And now you have to crash-land on this planet, and it's a desert. That can happen. You know, Earth has got deserts. Obviously, Earth is a planet. Mars and the moon both have a lot of sand-like soil we call regolith, so it's not unrealistic that if you came down on a planet that there would be a desert with lots of sand.

Rating: 2/10

"Star Trek Into Darkness" (2013)

Spock: Gravity systems are failing. Hold on. Scotty: There won't be time for evacuation if we don't get power to stabilize the d--- ship!

Kirk: Scotty, we've got to get the power back on, come on!

Garrett: When you're way out in the future and you're, like, "Star Trek" time, super-advanced with photon torpedoes and phasers and stuff and green women, you can just speculate that you've got some advanced technology. So, in the "Star Trek" world, we just have gravity plate that is degrading, according to Spock in this clip, and you can just wave your hands and do that. The thing about that is, so, let me tell you a story. I was up on the space station, and when you're up on the space station, they ask you, "Would you like to talk to anybody," like, any celebrities or interesting people. And they do that as kind of a morale boost. So I said, "Yeah, I would like to talk to Ron Moore and David Eick." They are the people that created "Battlestar Galactica." We had this video teleconference, and I said to them, "You know, you did the same thing. You come up with this artificial gravity on Galactica. Everybody's just walking around like they're on Earth, but you're out in the middle of space. Where's the gravity coming from? Why do you have to do that? Like, why would you take away one of the coolest things about being up here, the ability to fly?" And Ron Moore said to me, he said, "Garrett...you have any idea how expensive those special effects are and all those stunts?" So I get why, especially if you're doing something like "Battlestar Galactica" or "Star Trek" that you'd want to just say oh, artificial gravity. So I'm not gonna knock "Star Trek" down.

Rating: 7/10

"Apollo 13" (1995)

News anchor: The deadly CO2 gas is literally poisoning the astronauts with every breath in and out.

Control: OK, we have an unusual procedure for you here.

Fred Haise: They want you to rip the cover off the flight plan.

Jack Swigert: With pleasure.

Control: All right, now, the other materials you're gonna need here are two lithium hydroxide canisters, duct tape. You want to cut the duct tape 3 feet long.

Swigert: Houston, filter's in place.

Garrett: So, yes, that really happened. They had a big challenge because they had to find some way of scrubbing out the carbon dioxide inside the command module of Apollo 13 without having it powered up. So, humans make carbon dioxide. We consume oxygen. We breathe out carbon dioxide. And if that gets too high, bad things happen. You get headaches, and eventually you can even die if the carbon dioxide levels get too high. Now, on Earth we have a wonderful thing, it's called plants [laughs], that do this for us. And during Apollo 13, or in any spacecraft, you have to somehow accomplish it without having plants. And so we use a chemical called lithium hydroxide. It absorbs the CO2, but you use it up. Like, on the space shuttle, we had to change out the canisters of LiOH, lithium hydroxide, every so often. So they couldn't use the equipment inside the command module that normally takes all the carbon dioxide that we spew out and sucks that and scrubs that out of the air.

John Young: There's been an explosion. Oxygen tanks are gone, two fuel cells gone, command module's shut down. News anchor: And astronauts Jim Lovell, Fred Haise, and Jack Swigert are making their way through the tunnel to the lunar module, using it as a lifeboat so they'll have electrical power for their radios on the command module.

Garrett: They had to find some way to do it using the lunar lander, which wasn't intended to be used for that period of time for three people.

News anchor: With each breath, the three men expel more of the poisonous gas into the lunar module cockpit, and the scrubbers intended to keep the atmosphere breathable are quickly becoming saturated.

Garrett: They had to use some of the canisters from the command module. The thing was, the command module and the lunar module were made by two different companies. Because they were two different companies, they actually made them two different shapes. So one was round, and one was square. Well, they came up with a pretty good plan, which was that they made an adapter by using the cardboard or the cover of the flight plan, some duct tape, and some hose, and they found a way to make an adapter to use this square peg in the round hole. That's really the workaround that they came up with, and it worked. And so what you see in that movie is 100% real. They even used actual dialog. You know, NASA recorded all the transmissions to and from the spaceship and on the intercom, and so they had transcripts of what actually happened during the real Apollo 13. [alarm buzzing]

Swigert: Hey, we've got a problem here. Control: Uh, this is Houston. Say again, please.

Jim Lovell: Houston, we have a problem.

Garrett: "Apollo 13" is the gold standard. They got it right more than probably any other movie ever made about space. This movie is the closest thing to being a documentary without actually taking cameras up and filming it in space.

Rating: 10/10

Stephen Colbert: I've heard that you, in space, no one can hear you scream. Would you test that for me right now? Could you scream for us?

Garrett: Sure, Stephen, I'd be happy to. [audience laughing]

Colbert: It's true! It's true! No one can hear you scream!