Some Thoughts on the Movie, Gravity
Helen and I went to see this much-reviewed and much-discussed 3D extravaganza last night. No, this note is not going to be an astronomer’s sourpuss picking away at the movie’s scientific flaws, although I will point out a few things. Here are some thoughts:
1. I may be really dense, but I don’t understand the title. It really doesn’t have anything to do with the content of the film.
2. The 3D really works well most of the time, and the glasses that you have to wear are much more fashionable than the huge comic glasses that we had to wear in the old days of primitive red-green 3D. You feel that you can reach out and grab the floating loose screws and water droplets right from your seat.
3. More generally, the effects are really good. Weightlessness – or “zero G”, as even astronomers inaptly call it – is very difficult to simulate, so much so that for past space movies the producers have hired NASA training aircraft that climb to a high altitude and then fall ballistically (i.e. on a free-fall elliptical path), giving the occupants a few minutes of true weightlessness where they float around inside the aircraft just as in space. The producers of Gravity have done a really good job in simulating this effect. I don’t buy headline-grabbing astronomer Neil deGrasse Tyson’s picayune complaint about Sandra Bullock’s hair not floating properly. I thought that her hair was great.
4. On a related point: The depictions of the motions of objects in space are quite good. Every moment there is a decent display of Newton’s First and Third Laws of Motion. It’s really nice to see a space movie that respects how objects actually move.
5. The plot is pretty lame and contrived to me, as well as being, well, pretty much impossible from an orbital mechanics point of view. Lots of things also are just not true to life. As entertaining as it may be to watch George Clooney flitting around a space shuttle orbiter in a 1980s-style self-propelled backpack, tossing off anecdotes and humorous bon mots while scientist Bullock tries to concentrate on replacing a panel on the Hubble Space Telescope, that’s just not the way astronauts work and conduct themselves on a mission. I thought I was watching Dan Aykroyd and John Belushi (RIP) Meet the Space Age. Clooney-style cut-ups don’t make astronaut grade, and certainly don’t get assigned to missions.
6. This is more a matter of technical interest: The movie plot is based on the premise that (i) the Hubble Space Telescope, (ii) the International Space Station, and (iii) the imaginary Chinese space station, all share essentially the same orbit. This means that when one of them is destroyed by swarms of deadly satellite debris that whiz by every 90 minutes (inexplicably in the same orbit too, by the way), astronauts can conveniently move to one of the others nearby in an effort to save themselves. This is the biggest departure from reality in the movie (although I certainly wouldn’t say that it ruins the movie – that’s not really possible with Bullock and Clooney in it …). The HST is in an orbit about 570 km above Earth, inclined 28.5 degrees to the equator. The ISS, on the other hand, is in a much lower orbit (~420 km), with an orbital inclination of about 52 degrees. The result is that they never get anywhere close to each other, and it’s impossible to move from one to the other without enormous quantities of fuel.
All in all, Gravity is an interesting and entertaining film for a space enthusiast to see, but I must say that I’m a little surprised at the rave reviews and four-star ratings that I’ve been seeing. I think that they must be mainly for the considerable technical achievements rather than for the plot.