The Real Stories and Real Science Behind “Gravity”

By Corey S. Powell | October 7, 2013 4:21 pm

3/4/14 update: Gravity got a lot of love at this year’s Oscars, including a best-director award for Alfonso Cuarón and well-earned nods also for cinematography and film editing. Looking back at the movie now, I have two big thoughts. First–no, it cannot happen for real. The space-debris disaster scenario and the orbit-hopping from shuttle to station to station are not physically possible. And second–that artificiality is far less important than the deeper realism of Gravity, which does an exquisite job capturing the beauty and danger of humans tiptoeing off our planet and into the infinite void.

Astronaut Mike Massimino, whom I associate with the George Clooney character in Gravity (see below), clearly agrees. After the Oscars he posted a video congratulating the cast and crew, and explaining exactly why he thinks the movie is advancing the cause of space exploration. By coincidence, President Obama released NASA’s 2015 budget request a day later. The real-world support for Massimino’s vision of exploration is decidedly mixed. The agency gets funding to keep the International Space Station alive until 2024 and to start work on the exciting WFIRST space telescope, but overall NASA takes a slight pay cut from 2014.

Congress will undoubtedly make some changes. If you would like to have a say in the process, I urge you to contact your Senators and Representative.

Original post: When you take a science geek to a science-fiction film, no good deed goes unpunished. Throw together a bunch of narrative nonsense linked by sheds of technobabble and the boffins will enjoy your movie as high camp (see The Core, Armageddon) or indulge it as well-meaning drama (I’m looking at you, Prometheus). Try to be realistic, like the new movie Gravity, and pretty soon everyone from Neil DeGrasse Tyson to Time magazine (with spoilers galore) is fact-checking you for little slip-ups.

astronaut eva

The real deal: Astronaut Bruce McCandless zips around using NASA’s Manned Maneuvering Unit, back in 1984. Unlike what you see in Gravity, such suits are no longer in use, and astronauts remain tethered for safety. (Credit: NASA)

Let me start by saying this: Gravity is intense, riveting, and extraordinarily beautiful. It well deserves its critical and commercial success. If it plays fast and loose with some basic bits of physics–including, ironically, the laws of gravity–it gets a surprising amount right. So it is with affection, and a deep curiosity about space history, that I ask: Could the disaster depicted in Gravity really happen?I addressed that question briefly when I was on Fox News recently. The short answer yes, Gravity gets a lot of the fundamentals right. Space debris is a real problem. If debris compromised the International Space Station and any capsule docked to it, getting back home would be very hard. (OK, not just hard–it would probably be impossible without a rescue mission, but that would be a different movie.) Here I’ll break down the real science and stories behind Gravity, while avoiding spoilers as much as possible.

Clooney and Bullock. I had the good fortune of spending some time with the astronauts of the STS-125 missions during their training sessions in 2008. They are the crew that went up in the space shuttle to repair the Hubble Space Telescope–just like the fictional crew in Gravity. George Clooney’s character, Matt Kowalski, reminded me of the chatty and gregarious Mike Massimino, who has made repeat appearances on Big Bang Theory. Sandra Bullock’s character, Ryan Stone, was evocative of the younger and more reserved Megan McArthur. But: Astronauts spend a lot of time training before a mission. By the time I met Massimino, McArthur, and the rest of the crew they had an easy, deep rapport. The notion that they would still be learning basic biographical details about each other on the mission, as happens in Gravity, is useful for advancing the movie’s narrative, but doesn’t reflect the way real astronauts talk.


And the movie version: The aftermath of a space-debris disaster in Gravity (Credit: Warner Brothers)

The equipment. Gravity does a pretty good job showing how difficult it is to do basic things like removing circuit boards or tightening screws in space. The Hubble Space Telescope, space shuttle, and International Space Station are shown with a lot of realism. Astronauts really do rely on tethers when they do space walks, as shown in the movie. Kowalski’s flight suit is patterned on the real Manned Maneuvering Unit (MMU) flown by NASA in 1984. But: The MMU was abandoned by NASA after the Challenger disaster because it was seen as too dangerous. The only flying suit in use today is a little emergency pack called SAFER, which carries just 3 pounds of nitrogen propellant. Contrary to what you see on screen, NASA would not allow untethered flight even with a flight suit. And certainly no self-respecting astronaut would go stunt-flying around delicate equipment, using up all his propellant, as Kowalski does. But hey, it looks really cool on screen.

The movements. On the whole, Gravity does a fantastic job depicting the dreamy, slow-motion world of spaceflight. The scenes of laborious work on the Hubble telescope while the Earth looms overhead–all sense of up and down totally scrambled–are lovely and realistic. When things go wrong, Stone goes into a tumble and can’t stop. That’s the way things go in space–when you start moving you just cannot stop. It evokes a real-life, terrifying accident that happened three months ago when Italian astronaut Luca Parmitano suffered an internal leak in his space suit. His suit started to fill with water, covering his eyes and ears, while he went into a slow tumble. I highly recommend checking out Luca’s blog. But: This one has a MILD SPOILER attached to it. At one key point, Stone tries to hold onto Kowalski but he is pulled away, as if he is dangling over the edge of a cliff. At this point, everything the movie got right about spaceflight goes horribly wrong. Both astronauts are still in floating in microgravity. One tug and Kowalski would come floating right back. Oops.

Space debris

A partial map of the 500,000 known bits of space debris in low-Earth orbit. (Credit: NASA)

Space junk. If you’ve seen the Gravity trailer, you know that the whole chain of events in the movie starts with a swarm of space debris. Russia shoots down one of its old satellites, creating a hailstorm of orbiting junk that sets of a chain reaction. In fact there is a lot of debris in low-earth orbit: NASA is tracking about 500,000 pieces larger than 1 centimeter (roughly a half-inch) across. At that altitude, objects are orbiting at about 30,000 kph (18,000 mph), fast enough to make a crater. The Space Station is designed to survive a hit by a 10-centimeter (4-inch) chunk, but a hailstorm of debris could easily destroy shuttle and Station alike. Space engineers really do worry about space-junk chain reaction–sometimes called the Kessler Syndrome–and are looking at ways to reduce the amount of debris in low Earth orbit. But: The Russians know all about this and presumably wouldn’t do anything to create such a problem; in fact, they are prohibited from doing so by treaty. Debris in low Earth orbit wouldn’t knock out communications satellites, which circle at much greater altitudes. And MILD SPOILER you wouldn’t see the junk coming. It’s traveling at ten times the speed of a rifle bullet. Think how easy it is to see a rifle bullet coming your way. Uh huh.

Orbital dynamics. The Hubble telescope, Space Station, and another location in the movie (I’ll leave it unnamed) all have quite different orbits. You can’t just hop from one to the next. Neil DeGrasse Tyson was especially annoyed by this one. But I think it falls well within artistic license: It’s a way to dramatize the astronauts’ predicament, and Gravity handles the drama effectively, even if it isn’t realistic.

Astronaut risks. The whole point of Gravity is that life in space is incredibly dangerous and precarious. True enough. But: The greatest risks in space flight are takeoff and landing. Space itself is surprisingly safe in comparison. The statistics tell the story. A total of 18 people have died on space flights, but of those 18 only 3 have lost their lives in space proper: The crew of Soyuz 11, who died on June 30, 1971, when a valve failed and their capsule depressurized. Their deaths helped inspire the Fallen Astronaut memorial sculpture and plaque on the moon. The other 15 died during takeoff or landing. Another 11 died during training (including the 3 who died in the Apollo 1 fire). And far more people have lost their lives on the ground making spaceflight possible. An estimated 350 people have died due to rocket explosions, and 24 more in a variety of spacecraft factory and launchpad accidents.

Hubble repair

The fourth and final space mission to repair the Hubble Space Telescope, in 2009, looked very much like the scenes in Gravity. (Credit: NASA)

The bottom line: So what would really happen to you if you were stranded in space? The standard Space Station suit carries 8 hours of oxygen, plus a 30 minute reserve. If you cannot refill or find a safe haven in that time, CO2 levels build up and you eventually black out. With all that space debris flying around, more likely you would spring a leak in your suit.

If you depressurize, your timetable gets a lot more, er, compressed. Exposed to vacuum, you’ll pass out in about 10-15 seconds (and don’t try to hold your breath–the air pressure will explosively expel the air from your lungs). Animal studies show that monkeys exposed to vacuum for less than 3.5 minutes could be revived with no permanent brain injury. At that point, the animals’ hearts stopped and there was no turning back. One person was exposed to vacuum, during a 1965 ground experiment, and lived to tell the tale–take a look at this amazing video of NASA test subject Jim LeBlanc. Some other hair-raising case studies are here. Unless help were right at hand, the true ending to Gravity would likely be a grim one.

Watching Gravity, I was reminded of another recent sci-fi movie, one that paid even closer attention to the real details of a space mission: The smart, under-appreciated Europa Report. I thought about how incredible it is that so few people have died in space–not a single fatality since 1971. And I kept thinking, again and again, how spectacular the universe looks from orbit.

Gravity may be a disaster movie, but after watching it I was itching to go into space myself.

Follow me on Twitter: @coreyspowell

  • Mark Gubrud

    I haven’t seen the movie, so I don’t know what circumstances supposedly surround the Russian satellite destruction. I agree that Russia would be very unlikely to conduct such a shot that would pose a severe risk to American or any human spaceflight. However, there isn’t currently any treaty that would clearly forbid it. China conducted a satellite intercept (ASAT test) in 2007, and the US did one a year later. The US shot did not create significant debris because of its low altitude, but the US ASAT test in 1985 did. Moreover, the US conducts frequent tests of its “missile defense” weapons which are essentially the same type of weapon, which provides a plausible rationale for China to do the same, for the Indians to say they plan on it and Russia to certainly think about it. Nobody actually needs to conduct these tests in a way that creates debris–they can just pretend they are testing missile defense. But they might test against a satellite it if things get crazy enough.

    The proposed Code of Conduct, which would not be a binding treaty, might actually include some language that explicitly allows such ASATs to be used in case of “imperative safety considerations” or “self-defence.” The United States has long been opposed to any legal restrictions on space weapons or their testing. China’s recent activities are showing just how foolish the assumption of unilateral advantage which is the basis of that policy has been.

    You might argue that the 1967 Outer Space Treaty says you’re not supposed to create hazards of “harmful interference” and you’re supposed to provide notice if something you plan to do might create such a hazard, but the US didn’t think this applied in 1985 and China didn’t think so in 2007, either. It’s an arguable interpretation but it’s not explicit. The proposed Code language won’t help, either.

    • coreyspowell

      Very helpful additions, thanks. The Chinese satellite was in a polar orbit and at a relatively high altitude of 537 miles, both of which greatly reduced its risk to lower-altitude and lower-inclination objects like the shuttle and the ISS. But all your points are well taken.

  • Robert Muller

    With the “dangling off a cliff” scene… I assumed that the ISS was spinning and it was centrifugal force that was pulling him outwards.

    • disqus_atlq8Zmtsd

      That would be difficult to justify. They didn’t show any rotational perspective, which you would expect after that disorienting scene where Bullock was spinning.

    • coreyspowell

      In my experience, if you really like a sci-fi movie you can come up with a justification to explain away almost scientific error. The real test is whether the realistic things outweigh the improbable ones, and whether the overall movie is compelling enough that your brain wants to cover up the goofs. In this case, I’d say a definite yes on both points.

  • disqus_atlq8Zmtsd

    My first reaction to Clooney needing to let go was that he and Bullock were still drifting and had enough momentum that the chute wouldn’t hold them. Clooney letting go decreased the required impulse, so the need for him to die could work here.

    Problem is that you’re right. Bullock would have given one tug and he would have rebounded to her. DAMAGE DONE!

    The space stations being in the same orbit wouldn’t have bothered me if they had established it as being a decade or so in the future where they had built the infrastructure to allow for support in exactly these situations.

    The debris shower just required complete suspension of disbelief. You basically had to assume that both the debris and the astronauts were in perfectly circular orbits. For them to share the orbit but be at different speeds, they would have to be orbiting at the appropriate velocity in opposite directions.

    The idea that they would see it coming (both against the field of stars and simply because of how fast its moving) was completely preposterous. For realism things would just have to start disintegrating without ever showing the cause on screen.

    I don’t mind when they are inaccurate in things that SEEM like they are right or simply don’t matter. I noticed the floating helmet while she was violently tumbling, but I shrugged it off. When your entire premise relies on orbital mechanics and geography, you had better get it right though. Especially when you go to such extreme lengths to get a fetal position scene to emphasize just how artistic we’re supposed to think the movie is.

    Enjoyable as a dumb thriller. Fails as anything more.

    • Nightsong

      I don’t share your gripe about the debris field. When scientific accuracy and the necessities of narrative butt heads, you’ve got to pick your battles. I’m sure the film makers had scientific advisors with them every step of the way, but how do you create and maintain narrative tension if the audience can’t see the debris and doesn’t understand why it’s not visible?

      You can try to explain it, but that’s an info dump that hurts the narrative. The film already had enough exposition disguised as friendly banter.

      We like to criticize the scientific accuracy of movies and TV shows like this because it makes us feel smarter, but often it just shows we’re ignorant about the mechanics of storytelling. With that in mind, I can’t get too worked up about the debris.

      • disqus_atlq8Zmtsd

        I said that it just required suspension of disbelief. I didn’t say that it was an unforgivable sin or anything and said that the movie works as a dumb thriller.

        Am I supposed to treat it as a realistic, immersive world when there are things that are blatantly unrealistic and limit my immersion WHILE I’m watching? I should think not. It isn’t a misunderstanding of story telling to acknowledge what a movie is not.

        • Nightsong

          You said it was “preposterous” and that the scientific inaccuracies meant that the movie could be enjoyed as “a dumb thriller…nothing more.”

          Fine, whatever. Point is, 99% of viewers are not thinking of orbital distances, and I haven’t seen anyone propose a good narrative idea for how to keep the debris invisible while simultaneously maintaining narrative tension and explaining to the audience exactly why they can’t see the debris.

          But you’re Mr. Knowledgable About Space, so a mass-market science fiction thriller (note the word fiction in the genre description) should be tweaked to satisfy your demand for scientific accuracy, audience comprehension and critical praise be damned.

          It’s one thing to point out inaccuracies and quite another to call a film preposterous and dumb just because you don’t understand the demands of storytelling. And before you get your Neil Tyson Degrasse t-shirt in a knot, go back and read your own posts and no belligerent they are.

          • disqus_atlq8Zmtsd

            Armageddon is one of my favorite movies, dumb thriller that it was. I certainly didn’t mean that the movie was dumb in a sense that it wasn’t a worthwhile watch. Its the same distinction that is made between “literature” and genre fiction.

            I perfectly understand why the debris was visible in the narrative context, but that doesn’t mean that it didn’t pull me out of the experience. It was PREPOSTEROUS in that it was contrary to reason and common sense. Narrative imperative justifies it but does not make it any less preposterous. Again, that isn’t a bad thing on its own as my love of Armageddon shows. Suspension of disbelief is a very important tool for the movie goer, but it does limit what a movie can claim to be.

    • Michael O’Brien

      Dumb as most propaganda films are . This is what this film is about . They complain about NASA’s budget well this will give lots of folks without a clue (FOX ) a reason to hate Obama & say he is not concerned with our safety . I will admit that we are more at risk from this threat then we ever were from WMD’s . What is the ALERT Color today ? Scare Tactics to sell a Trillion $ war that benefits what,who ?

  • Betterose Ryan

    Loved the movie. I am not a scientist but the whole Clooney having to let go REALLY bothered me. I didn’t see any rotation either since his position with respect to the earth didn’t seem to change. Still, loved the movie.

  • jen

    one more thing, her tears would not float off her face beautifully. They would form a water ball on her eye, but that looks horribly unattractive, so they edited tears floating around her

  • allbuss84

    The Hubble telescope, Space Station, and another location in the movie (I’ll leave it unnamed) all have quite different orbits.

    Kinda like how they manage to fit every casino in Las Vegas in movies (Conair was the worst) even though they are off strip or miles apart.

  • anw1652

    I saw only one other comment on this, which most obviously jumped out at me: the debris field. If a missile had destroyed a satellite, the various chunks of debris would fly out into all directions essentially randomly (think 3D billiard rack in microgravity slammed by a hypersonic vehicle, and, presumably, a concurrent detonation), and wind up in all sorts of different orbits- they would not “hang together” like some massive hail storm in an orbit that was perfectly retrograde with respect to the ISS, et al. And, as pointed out, these orbits are low earth, LEOs, say approx. 200-300 mile altitude. Communications satellites, except for some specialized applications, but in particular NASA’s TDRSS satellites (Tracking and Data Relay Satellite System, which is what they use to relay comm to and from the shuttle and probably ISS, not sure about that) are in geostat orbits, 23000+ mile altitude. Very little chance of a random piece of debris knocking out even one comm satellite, much less all of them.

    Wondered about the hanging off a cliff thing- didn’t even think to suspend belief, just couldn’t figure out what the scenario was. And all the orbital transfer comments here are spot on,as well- picked up on that. You don’t just “point and shoot thrusters” as depicted; there are complex transfer orbits into which and out of which the vehicle must maneuver in order to change from one stable orbit to another.

    BTW, for anyone who’s interested: LEO is generally defined as an orbit between 160 & 2000 km. A little curiosity and arithmetic shows that to be a volume of about 33.5 x 10^9 cu km, which means there is a mean density of those > 1 cm particles of about 1 particle in 67 THOUSAND cubic km of space- a cube about 41 km on a side.

    Low probability of intercept. Of course, if you did…

    • Chuck

      TDRSS does support ISS

  • Daniel Collins

    On seeing debris moving at 50,000 mph.
    In physics, speed is relative. Look at a stationary object hen you drive past it. The object appears to move, even though you know that you are the one moving. Its a matter of perspective.
    The debris was moving at 50,000 miles an hour relative to the Earth. The characters are in orbit around the earth, at approximately 17,000 mph. To them, the debris would be moving much slower. Not a perfect justification, but it helps with suspension of disbelief.

  • Anpadh

    You guys, you gotta be like Einstein. Supposedly, a few years after Einstein published his Theory of Special Relativity, an 8-year-old boy wrote him a letter asking how come Superman could fly faster than light when Einstein said nothing go could faster than light. I’m pretty sure Einstein knew a little Physics, but he still wrote back to the kid, saying, something like this: “All I have is a theory. Superman’s speed is a fact.”

    • Zapp

      This story is very cute, even if it’s totally made up. Besides, Superman appeared 30 years after the TOSR was published.

      • The Plothole

        Not only that, but Superman didn’t have the ability to fly when he was first introduced. And he was barely faster than a “speeding locomotive”.

  • Paul Emmanuel A. Ariate-Clark

    can somebody explain the scene where sandra pose for a ‘baby like in the womb position’ where cables represents as an umbilical cord..and the shore scene where sandra has difficulty walking, crawling at first. anybody?

  • Serah Michelle Umoren

    can you guys just stop criticizing for once and enjoy the freaking movie. Stop trying to nitpick every little mistake that is made.

  • Jonathan Maglasang

    it should have been with the Chinese shooting its own satellite that started the Gravity chain of events- a reminder for the junkies it created in early 2007.

  • Christine Moyer

    I was so excited to see this movie, Clooney & Bullock, that makes it epic. Unfortunately I thought it was dumb. While it had me breathless in the beginning I slowly came back down to earth and found it was the same cheese receipe as american idol.. Happy family pic on the dead guy, dead head pops out of the ship as they look in, my kid died so feel sorry for me drama, floating tears, Clooney ghost, fire extinguisher space station hopping….. I expected a higher level of creativity. Their moon is made of cheese.

  • Vichy41

    It is a movie, can’t you just enjoy it? Who cares about tears and junk being realistic? I never was and never will be in space, therefore, I just watch performance and I liked it.
    We’re not discussing scientific facts here, right?


Out There

Notes from the far edge of space, astronomy, and physics.

About Corey S. Powell

Corey S. Powell is DISCOVER's Editor at Large and former Editor in Chief. Previously he has sat on the board of editors of Scientific American, taught science journalism at NYU, and been fired from NASA. Corey is the author of "20 Ways the World Could End," one of the first doomsday manuals, and "God in the Equation," an examination of the spiritual impulse in modern cosmology. He lives in Brooklyn, under nearly starless skies.


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