Gravity: An Amazing (Albeit Highly Unscientific) Film.

It should come as no surprise that my favourite movie genre is science fiction. Even though I was born long after the original Star Wars trilogy had finished watching it with my parents is still one of the fondest memories I have and that has long since bloomed into a passion for the genre. Of course this also feeds into my love of sciences as whilst I also enjoy fantasy, in all its forms, nothing quite compares to plausible futures that are based on real science. Whilst I understand that scientific accuracy will often take a back seat when the narrative requires it I can’t help but feel compelled to point out some of the more obvious flaws, especially when it’s such a big movie like Gravity.

Gravity 2013 WallpaperNow before I launch into this let me just be clear: I absolutely enjoyed Gravity. Whilst I was sceptical about George Clooney and Sandra Bullock being able to bring life to the roles they were given it didn’t take me long to warm to their characters. I was also very surprised by how much tension I felt for multiple different scenes, something which I don’t typically feel, at least not to that extent. All this, combined with the beautiful cinematography culminates in a movie that’s thoroughly enjoyable even if you take the hard line with science like I do. With all that being said though there are some points which bear mentioning and should have you not seen the movie I’ll advise you to skip reading on.

PLOT SPOILERS AHOY

The first thing that I, and several others, have taken issue with is the notion that from the orbit of the Hubble Space Telescope you’d be able see both the International Space Station as well as the Chinese Tiangong station (which is way more developed than current plans indicate, but that’s another story). Even if all of them shared identical orbits, which they don’t, the Hubble is in an orbit that’s some 200KM above the ISS and Tiangong making any naked eye visual impossible. Following on from this the idea that you’d be able to then travel between them becomes somewhat difficult as the energy required to do the plane change manoeuvres would be far above the capabilities of Manned Manoeuvring Unit. Indeed the backup plan NASA had for a shuttle that had suffered a catastrophic failure event such as the one in Gravity was to send another shuttle up there to rescue them, dubbed STS-400, which was the reason why we saw 2 fully fuelled shuttles on their respective launch pads the last time we serviced the Hubble.

I’m sort of able to forgive that for the sake of story however one moment that I won’t was when Bullock is holding onto Clooney’s tether and he says he has to let go or they’ll both be doomed. You see at that particular point there’s no more forces acting on them as once they got tangled up and stopped moving all their momentum had been transferred to the ISS, rendering them at equilibrium. If Bullock had simply tugged on the tether slightly Clooney would have then started drifting lazily towards the ISS and Bullock could have pulled herself back along the parachute cords. I would’ve let that slide if it was a minor side point but it’s one of the main turning points of the movie and unfortunately it just has no basis in reality whatsoever.

One thing I was also going to pan Gravity for was the use of fire extinguishers as thrusters since I figured the amount of delta-v available in them wouldn’t have been enough to provide any meaningful thrust. As it turns out, depending on what kind of extinguisher you have, there could be as much as 100m/s in them, a heck of a lot of thrust by any means. Whilst you’d be far more likely to send yourself into an unrecoverable spin if you were using them in the way shown in Gravity it does lend some credence to the idea of using it to correct your trajectory in order to intercept something else.

PLOT SPOILERS OVER

There were also numerous other minor details but compared to the previous few I mentioned I don’t think they’re worth digging into. Whilst there really were some cringe inducing moments from a science perspective it is a highly enjoyable film, even if you’re not into the whole space scene. It’s also worth it to see it in 3D, something I don’t say often, as the producers have taken care to use 3D as a tool rather than slapping it on in order to increase the ticket price. It might not be super hard sci-fi but then again not many films are and ones of Gravity’s calibre are even rarer.

 

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  1. I was all worked up to them to task on that particular issue as well but it didn’t take long for me to stumble across that delta-v thread which showed me otherwise. I’m glad I did too as I would’ve just gone with my gut otherwise rather than attempting to do the delta-v calculations myself 😉

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