How Scientifically Accurate is Gravity?
- 11th Jun 2025
- Author: Alex Thompson
The evolution of Sci-Fi in movies
For over 120 years filmmakers have used the public’s fascination with space to create and sell movies. It’s believed that the 1902 French flick “Le Voyage dans La Lune” or “A Trip to the Moon” was the world’s first sci-fi film, with its special effects, style and popularity paving the way for some of the most iconic films in Hollywood history, including Star Wars, Alien and E.T.
As the years have progressed and our understanding of space has improved, a lot of filmmakers have turned to a new genre; the scientifically accurate sci-fi. Whilst there’ll always be a place for imaginative fantasies set in galaxies far, far away, this more realistic version of science fiction helps sell the authenticity of the plot to an audience, allowing them to invest emotionally and mentally in a way they couldn’t in a world of fictional physics. In fact, many sci-fi creators now consult with real experts to produce and direct the most authentic version of their plot possible.
But just how scientifically accurate are these films? Whilst it would be harsh to judge “Le Voyage dans La Lune” for its realism (spoiler – it’s not very), we can look at some of the films that have made an honest attempt to get things right. In this series we are going to study some of the most popular space films of the last few years, analyse the science and give them a rating, which I will imaginatively call “Space Realism Rating”.
We'll start with the 2013 blockbuster ‘Gravity.’ You may have loved the movie, but could it have happened? Let’s find out….
The plot (spoilers ahead)
This two-actor show is essentially a ninety-minute, heart-attack inducing journey following Sandra Bullock’s desperate attempts, as Dr Ryan Stone, to get back to Earth following an in-space collision.
The destruction of a defunct Russian satellite causes a flurry of debris which hits astronauts working on the Hubble space telescope.
The rest of the film sees Bullock and George Clooney (as Lieutenant Matt Kowalski) until he selflessly sacrifices himself, trying to transport between various spacecrafts and stations to find a way home before the flying debris destroys everything.
What it got right
Some extraordinary attention to detail is shown regarding some of the film's finer details; the accuracy of the Earth’s atmosphere, the speed things travel at in low-Earth orbit, how realistic the Soyuz and ISS looked (even if some of the modules weren’t necessarily in the right order in the latter.)
Indeed, even the buttons and valves used by the astronauts in the film would be the correct ones they would use in a real space mission, such as Bullock turning the valves on the Soyuz.
Astronauts and experts have given the film credit for getting ‘the feel’ of space right, particularly the EVA at the start, with experienced spacewalker Garrett Reisman saying it did an “outstanding” job of the movement and visuals, even if there always seemed to be land the astronauts could look down on when looking at Earth instead of the oceans they are often greeted with in real life.
Clooney warns Bullock they have “about 90 minutes” before they’re struck by more debris. This is correct as in low-Earth orbit things travel at over 17,000 miles per hour, meaning that it would take around an hour and a half to circle the Earth (the ISS has 16 sunrises and sunsets a day because of this).
Gravity also successfully shows the dangers of space debris and the Kessler syndrome. This is the idea that there may soon be so many objects in orbit around the Earth that if two were to collide (at the high speeds they're moving at) it would create cascading trail of debris that would collide with more satellites – this would cause a domino effect.
It would ultimately end with everything destroyed and the inability to send anything into space without the high risk of being damaged, due to the infinite amounts of debris surrounding our planet. It is a very real worry in the scientific community that is in full swing here, although some creative license was used to ensure its maximum effect.
What it got wrong
The biggest scientific flaws of ‘Gravity’ come from an impossible initial problem and a very improbable, if not completely impossible, final sequence. There is another film we’ll look at later in the series where these two things happen. Debris from a Russian satellite takes out the Hubble, ISS, communication satellites and more. One problem – the ISS orbits at roughly 400 kilometres above the Earth, Hubble at 547 kilometres, and most communication satellites are in geosynchronous orbit at 35,000 kilometres!
The destroyed satellite, I assume, is in the latter orbit, meaning the ISS and Hubble are in no immediate danger. Even if it was in low-Earth orbit with those two spacecraft it might not affect communications, so the astronauts would still be able to talk to mission control. There is also no way that Hubble, the ISS and Tiangong-1 would be as close together in real life as they appear in the film thanks to their differing heights and orbits.
As for the ending, yes, technically using a fire extinguisher to propel yourself through space could work, but would be near impossible to control, especially the way Bullock's character, Dr Ryan Stone, is using it. There’s also an ongoing argument in the scientific community as to whether Clooney's character, Lieutenant Matt Kowalski, had to be sacrificed. Some argue that Bullock not being able to hold Clooney’s weight wouldn’t be an issue in a weightless environment, and a simple tug on the cable would have sent him the other way. Others, including the film’s scientific advisor Kevin Grazier, point out that since both are still decelerating as they become tangled they still have too much kinetic energy for the cables to hold them.
Conclusion
There are of course smaller inaccuracies; Sandra Bullock’s tears wouldn't float off but form a ball on her face. The fact she is effectively in underwear underneath her spacesuit, not wearing any of the cooling systems needed for an EVA or indeed a nappy (I hope she didn’t need the toilet on her spacewalk.) Additionally, the astronauts using jetpacks whilst fixing the Hubble Space Telescope takes us out of reality, since these haven't been used since the nineties. There's also the oddity of one of characters messing around with his jetpack (there’s a reason George Clooney chose not to try and save him – he should never have been in space). I also found myself screaming at Bullock to put her helmet on several times, whilst also admiring her super-human speed at getting her spacesuits on and off.
These are minor things that are, of course, used to enhance the cinematic experience. Simply, the movie gets things right when it can and cheats when it can’t. The fact that what could or couldn’t happen in this film is so hotly debated is a credit to the way that Gravity presents itself.
It tries and that’s good enough for me.
Space Realism Rating: 7/10
Full references / credits:
(Banner) Just how accurate is Gravity? Credit: National Space Centre
(1) The world's first sci-fi, La Voyage Dans la Lune (1902). Credit: Public Domain
(2) The Hubble Space Telescope in orbit above Earth. Credit: NASA
(3a) The Kessler Syndrome involves a domino effect of colliding satellites. Credit: ESA
(3b) Artist's illustration of a debris-spawning event in Earth orbit that can cause the Kessler Syndrome. Credit: ESA
(4) It's a long distance to travel from Geosynchronous orbit to collide with Hubble and the ISS. Original Image: https://en.wikipedia.org/wiki/List_of_orbits#/media/File:Orbits_around_earth_scale_diagram.svg
(5) Hubble being serviced in real life. Credit: NASA
