Spoilers won’t spoil Gravity


Gravity is a thoroughly enjoyable science fiction survival movie with a refreshing amount of attention paid to the finer details, and some wonderful depictions of weightlessness.

Although Gravity has been subject to criticism by everyone from Phil Plat (the bad astronomer) to Neil deGrasse Tyson because of the liberties taken with orbital mechanics, it’s important to realize that they and all the other critics still LOVED this movie. It seems the Gravity is a movie you can’t spoil.

Even knowing the faux-pas didn’t deter me from seeing Gravity on the big screen in 3D this weekend. If anything, knowing about these issues in advance (many of which are evident in the numerous trailers) allowed me to enjoy the movie all the more.

The issues that seem to be raising the ire of some are largely forgivable. They hinge on:

  • MMU (the jet-pack like manned manoeuvring unit used by George Clooney) has very limited fuel. MMUs are the NASA equivalent of a bicycle and could not be used for long-range travel as they are in the movie, although to their credit, the writers cover off on this by saying George has a long-duration prototype.
  • Distances and relative speeds are compressed for the sake of storytelling. Communications satellites orbit at 22,000 miles so as to be geostationary, not the 220 odd miles depicted in the film
  • The debris field produced by a chain reaction of satellites exploding s.t.r.e.t.c.h.s. credibility. Such a chain reaction isn’t possible, and if it did occur the debris cloud would not cluster together at one altitude (a lot depends on what kind of chain reaction “explosion” we’re talking about)
  • Velocities are interesting to consider. A satellite in orbit at at the same altitude as the International Space Station is going to be traveling at 17,000MPH. If it’s struck by a missile with something similar to C4 as an explosive, the shrapnel generated by the explosion will be accelerated by up to 20,000MPH in all directions. Some of it will fall back to Earth. Some of it will be accelerated beyond the escape velocity for an Earth orbit (which is roughly 25,000MPH) and will enter an orbit around the Sun. The rest will enter all sorts of weird and wacky, highly eccentric orbits in between. It’s going to be a mess, but it’s going to be a far-flung mess.
  • Hubble, the International Space Station and the Chinese Space Station are all in entirely different orbits, not just in terms of altitude but inclination. This may not seem like a big deal, but moving between such disparate orbits is hideously fuel-expensive, so much so it’s often easier/cheaper to launch separate missions than to go flitting around between them in orbit!
  • Debris (and people) won’t fall away toward Earth when something catastrophic happens (Newton nailed this five hundred years ago)
  • When our astronauts are tangled in the parachute cord and the tension is reached on the tether, pulling the line taut, both Sandra Bullock and George Clooney would have rebounded back toward the space station without the need to do anything. Their reaction would be much like a yoyo on a string.
  • Space is not flat. Although someone might appear to be “floating in zero gravity” the reality is their motion (and any change in their orbit) is more akin to NASCARs racing around a steep bank
Orbital mechanics is a lot like NASCAR driving around a banked track. There's no zero gravity, only freefall. And changes in orbit work much the same way as changes on the sloping bank

Orbital mechanics is a lot like NASCARs driving around a banked track. There’s no such thing as zero gravity, only a blisteringly fast freefall in a gravity well. Changes in orbits work much the same way as changes on a sloping track, with different speeds positioning the cars at different heights.

But for all that, there is an astonishing amount of detail Gravity gets right, from the interior of the International Space Station, to the cramped, claustrophobic cockpit of the Soyuz and the sweeping vistas of Earth as seen from a low orbit.

Charles Simonyi has been on board the International Space Station on two occasions, both times traveling to and from the station in a Soyuz. He made the following observations about the movie Gravity.

Charles Simonyi oversaw the development of Microsoft Office

Charles Simonyi oversaw the development of Microsoft Office before becoming a space tourist

I’ve also heard from other astronauts that they liked the way Sandra Bullock complied with the first rule of a space flight emergency: RTFM – Read the @#$ing manual.

Gravity - Soyuz

Thankfully, she has a copy of Soyuz-for-Dummies as there’s no iOS or Ice Cream Sandwich on this vintage spacecraft

Gravity - Outside

Look at how perilously thin the atmosphere is… if Earth were the size of a basketball the bulk of our atmosphere would be no thicker than a single sheet of plastic Saran-wrap

Inside the International Space Station

Considerable care has gone into replicating the inside the International Space Station

Even though the orbital maneuvers were oversimplified, Buzz Aldrin loved Gravity because it gets so much right and awakens our sense of awe for space flight. Sure, there’s some nitpicking on the physics, but the vast majority of details are astonishingly precise and incredibly well portrayed. 

Five stars from me.

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5 thoughts on “Spoilers won’t spoil Gravity

  1. I’m amazed at the number of people who think that astronauts in low-Earth orbit float because they are SO FAR from Earth that Earth’s gravity has no influence on them.

    I like to throw pie in their faces.

    Suborbital pie.

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