Science fiction films are often more fiction than science—pew pew lasers, dense asteroid fields, and ships in hyperspace, for example—but every now and then filmmakers do their homework. Sure, space-time/dimension manipulation a la Interstellar is the stuff of cosmic lore. At the same time, a handful of directors behind some truly out-there epics will occassionaly feature details that can actually teach viewers about the ins and outs of space travel. Below, we’ve highlighted a couple classics that get space science right.

There isn’t much gravity in space, so astronauts have to make it.

Director Stanley Kubrick wanted his depiction of space in 2001: A Space Odyssey to be scientifically plausible, which was no small feat in 1968 when we had yet to send a man to the moon. Kubrick and his crew studied the science (including NASA-funded studies) so that they could accurately model things like the Discovery One spacecraft’s interior and exterior. A key feature of the spaceship is its Centrifuge, a large rotating wheel that generates artificial gravity so that astronauts don’t float constantly and won’t suffer the mental and physical effects of prolonged exposure to microgravity.

Sleep is the best way to travel in deep space.

Sci-fi films that feature crews going to space for long stretches of time often show them literally frozen for the journey and thawed upon arrival, or they use the more scientifically-sound method of inducing a hibernation-like state. Now that some people have their sights set on Mars, NASA-funded scientists are thinking of ways to keep astronauts alive and healthy for the six to nine months that it would take to get there. Aerospace engineers are looking at therapeutic hypothermia technology as a possible solution. The practice could lower the body temperature of the astronauts, reduce their metabolism, and put them to sleep, which would help because they could pack less food and water and reduce the size of the vessel. More research needs to be done on the recovery process and the effects of prolonged stasis on healthy subjects before this becomes a real thing, but at least it’s not a random idea that Hollywood invented.

“In space no one can hear you scream.”

The quote is remembered as the tagline for the 1979 film, Alien, but it was best realized in Kubrick’s 1968 classic 2001: A Space Odyssey. In scenes set outside of the spacecraft, the film goes quiet. When one character ventures out in a pod to make a repair, you hear his breathing and a hissing noise, but when he is sent spinning into space and the air hose to his oxygen supply is severed, it goes completely silent. In space you would be able to hear radio transmissions because radio waves are electromagnetic (not mechanical), but screams would go unnoticed because the particles in space are too spread out. Interstellar dust could potentially carry sound waves, but the frequency would be too low for human ears to hear.

 

You can survive unprotected in space, but not for long.

Audiences were skeptical of the scene in Guardians of the Galaxy where Star-Lord risks his life by removing his helmet in space to save Gamora, but it wasn’t as far-fetched as it seems. According to NASA and research conducted on animals in near-vacuums back in the 1960s, death in space would not be instantaneous. It is plausible that someone sucked into space could survive if they were rescued quickly enough.

The soil on Mars can be used to grow food.

You’ll need to be as smart as Matt Damon’s character in The Martian to pull it off, but NASA has confirmed that the soil on the Red Planet has all the right nutrients and with some added science, it could be used for growing plants.