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Film review: Gravity (2013) (no spoilers)

I watched the film in its recommended 3D version and it was enjoyable. The film belongs to the genre of disaster films where people are stranded in a remote place because of an unfortunate series of accidents. There is no place more remote than outer space and the set up for this film is when a space shuttle repair mission to the Hubble telescope is bombarded by space debris that causes havoc.

Almost the entire film takes place in space at the orbital height of the Hubble and the International Space Station and so takes place in zero gravity or, to be slightly more precise, micro-gravity. The difficult thing about filming zero gravity scenes is that there is no way to shield the effects of Earth’s gravity to make things weightless. Unlike all the other forces, gravity acts on everything all the time and there is no getting around it.

The only way out is to use the Equivalence Principle that says that the observable effects of gravity are identical to those that would be observed in an accelerating frame of reference. Hence the force we feel on the Earth due to gravity (which creates a downward acceleration of 9.8m/s2 for freely falling objects) would be indistinguishable from what we would see and feel if there were no gravity force at all but the ground beneath our feet were accelerating up at the rate of 9.8m/s2 (ignoring the small non-uniformity of the gravitational field due to the sphericity of the Earth).

So if we could be inside a container that was falling down with an acceleration of 9.8 m/s2, then the combined effect of those two frames (the downward accelerating container and the upward accelerating ground) would cancel each other out and, voila! we get zero gravity. This is how the astronauts train for zero gravity, by going to high altitudes in a jet plane that then cuts its engines and falls freely. As it falls, the astronauts inside the plane feel truly weightless.

The catch about filming zero-g scenes is that on Earth one cannot have free-fall for very long times since you soon hit the ground. This makes filming extended zero-g scenes impossible. Some space films ignore this problem altogether and have people walking around as if gravity still exists in space. Others, like 2001: A Space Odyssey, create spaceships and space stations that rotate in a way that simulates gravity by creating accelerations. Others use unseen wires and the like to make things seem to float.

One thing the film makes clear is that the shuttle orbit is quite close to the Earth since we can see the Earth dominate the sky and can make out cities and major geographical features. At the height above the Earth that the Hubble is, the force of gravity due to the Earth is still considerable, about 85% of the value on the surface of the Earth. The reason we think of it as zero-g is that the shuttle is freely falling and so we have the same cancellation effect as the one I described above. The difference is that as the shuttle falls to the Earth, it does so in a parabolic path because of its lateral speed, the way a ball behaves when it is thrown. But the shuttle is high enough and is moving fast enough that the shuttle does not hit the Earth because, due to its curvature, the surface of the Earth keeps ‘falling away’ at the same rate. That is what an orbit is. We could, in theory, put a baseball in orbit near the surface of the Earth by throwing it fast enough horizontally so that as it falls, the Earth’s curvature ‘falls’ at the same rate. The problem is that the Earth’s atmosphere would cause the ball to burn up.

A major problem with simulating zero-g is the behavior of hair and loose clothing. While rigid objects can be suspended by wires and the like and made to look as if they are freely floating, in zero-g hair and clothes would simply separate from the head and body instead of clinging to it, and that is hard to simulate. In Gravity they do an excellent job of filming extended scenes in zero-g (I don’t quite know how but I suspect with wires and CGI and camera angles) and they get around the hair-clothes problem by keeping people’s hair short and having them wear either fairly rigid spacesuits or tight clothing. Some critics have carped on some details of the film as being scientifically inaccurate but those would not be noticed by anyone. I have never been in space of course, but this film supposedly conveys quite accurately what it is like and much of it was visually beautiful.

It was an enjoyable film, keeping you in suspense. There was some maudlin religious sentimentality thrown in and but it was not too bad. Was it great? I would not say that. What it did do very well was simulate a zero-g environment and when awards season comes around, cinematography and special effects prizes seems likely.

Here’s the trailer.

Comments

  1. Thud says

    Good exciting entertainment-popcorn recommended.
    Surprising good microgravity effects, as noted.
    The Hubble telescope is not at the same orbital height as the International space station, not even close, not to mention the great difference in orbital plane inclination. This is a story-breaker, if you understand orbits, so you just have to ignore it and a few other things, to enjoy the movie.

  2. Zain says

    It’s nice to see people taking interest in a movie that takes place in space, but there isn’t much to Gravity beyond the special effects.

    Here’s hoping that in the next few decades another film like 2001: A Space Odyssey will be made.

  3. OverlappingMagisteria says

    For filming the zero gravity scenes, I’ve read somewhere that everything in the opening scene was CGI except for the actors’ faces. I assume the same is true for all the scenes that took place outside of any space station. Turning off gravity on Earth isn’t possible, but on a computer it’s easy.

    When filming “Apollo 13″ they actually filmed some of the zero-gravity scenes by building a set inside an airplane and taking it for a few free-fall dives. They could only do short takes because, as Mano said, you only have so much time before you hit the ground. Other scenes were filmed with wires or having them sit on an off-screen chair that drifted around a bit to make it look like they were floating.

  4. Wylann says

    The “zero -G plane” referred to above, is affectionately called the Vomit Comet by NASA. It’s an old 727 that has 16-20 seats near the back, and the rest of the deck is all open, with padding on the walls and floor. If you search for it on youtube, there are lots of videos of people riding on that aircraft. Personal note: I’ve been on the plane, but only while it was on the ground. The company I worked for used to do repairs, and we did some minor repairs/maintenance on that one. I’m not sure if NASA has more than one. I’ve also been on both of the 747s that used to carry the space shuttle. :)

  5. Pierce R. Butler says

    Raging Bee @ # 2: … what parts of the science are bullshit?

    Start with the sounds-of-breaking-hardware-in-a-vacuum part.

    I suspect I would most enjoy this movie on a large screen with the audio turned off.

  6. moarscienceplz says

    I saw it last weekend. The orbital anomalies bothered me, but I was especially disturbed by the idea that George Clooney could just go joyriding around with his jetpack in the opening scene. Even after setting all that baggage aside, I just couldn’t work up any emotional attachment. Maybe because both Clooney and Sandra Bullock did so much stuff that real astronauts would avoid, such as hyperventilating and thus wasting her suit’s oxygen, that I could never suspend my disbelief and get into the story. However, it was a very pretty and technically amazing movie, so I never felt an urge to walk out of it.

  7. says

    Planetes is a near future hard science fiction manga/anime that follows the activities of the Debris Section, blue collar space workers who’s job is to go out and deal with all the junk building up in Earth’s orbit.

    To quote the linked wiki page:

    Unlike many other anime and science fiction productions, special care was given in Planetes for a very realistic depiction of space and space travel. For instance, when in a weightless environment, the cel count dramatically increases in order to make weightless motion more fluid and realistic. Also, spaceships make no noise in the vacuum of space and astronauts routinely suffer from known space illnesses such as radiation poisoning, decompression sickness, cancer, brittle bones and mental illnesses spawned from isolation in the vacuum of space.

    I found it quite gripping and, from a layman’s perspective, quite reasonable in terms of science. This post reminded me of the show so I’d figure I’d ask if you’d seen it.

  8. Zain says

    Just to add to this– the entire show is only twenty six episodes long, so you don’t have to put in an extraordinary amount of time to see it all. And it’s absolutely worth watching for any fans of realistic science fiction.

    Although it was created in Japan, Planetes features characters from a wide variety of nationalities. From Wikipedia:

    The story also depicts the richer countries monopolizing resources in space and the poorer ones falling into civil war and being invaded or needing the assistance of those richer countries, telling a story of dependency theory and the negative side of environmentalism. The conflicting views of the terrorist group, the Space Defense Front, who wish to shut human beings off from space, the main characters who believe in the importance of space exploration and development, and the International Treaty Organization (INTO) which wants space development primarily to serve the economic and military needs of developed nations also play major roles. The anime refrains from oversimplification of the various factions, portraying both true believers and those with ulterior motives on all sides.The final settlement of the conflict is also unique in that it is not resolved by any of the main protagonists or antagonists, but by a compromise struck between powers above their heads.

    Both the anime and manga set a precedent of portraying a highly multicultural cast of characters. Usually, characters who refer to anime stereotypes are immediately berated by other characters.The story also depicts the richer countries monopolizing resources in space and the poorer ones falling into civil war and being invaded or needing the assistance of those richer countries, telling a story of dependency theory and the negative side of environmentalism. The conflicting views of the terrorist group, the Space Defense Front, who wish to shut human beings off from space, the main characters who believe in the importance of space exploration and development, and the International Treaty Organization (INTO) which wants space development primarily to serve the economic and military needs of developed nations also play major roles. The anime refrains from oversimplification of the various factions, portraying both true believers and those with ulterior motives on all sides. The final settlement of the conflict is also unique in that it is not resolved by any of the main protagonists or antagonists, but by a compromise struck between powers above their heads.

  9. StevoR : Free West Papua, free Tibet, let the Chagossians return! says

    Some critics have carped on some details of the film as being scientifically inaccurate but those would not be noticed by anyone.

    Hey! I noticed them straight away and quickly found myself losing suspension of disbelief because of them.. Am I not “anyone” eh? Okay, I’m a massive fan of space exploration and astronomy and probably atypical but still.

    @ 2 Raging Bee : “Kevin, what parts of the science are bullshit?”

    What Thud said in #3. This is the key reason why HST repair missions have been so problematic and more risky than usual precisely because the Shuttle astronauts cannot get to the ISS to use as a lifeboat in case of emergencies. Thought that fact was fairly well known? Especially after the loss of the ‘Columbia’ and the subsequent investigations.

    Also, whilst its not exactly science, I’d start with the fact that we’re flying one of tehnow retried Sapce Shuttle’s (one of the modern wonders of the world in my view) with a made up orbiter name at that. If they had to go with a Shuttle they could have at least used one of the existing names – Discovery, Atlantis or Endeavour.

    Then there’s the matter of someone flying a mission after a mere six months of (at best partially effective) astronaut training – I don’t think so!

    See also my comment here :

    http://freethoughtblogs.com/singham/2014/03/02/kareem-abdul-jabbar-critiques-the-best-picture-nominees/#comment-1552436

    Plus one on new FTB blogger Kaveh Mousavi’s ‘On the margin of error’ blog “The Academy Should Award Steve McQueen Tonight”thread where his prediction duly came to pass.

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