Gravity: The science behind the movie

Kevin Grazier, the science advisor for Alfonso Cuarón’s new sci-fi thriller Gravity, talks about the concepts behind the movie and explains why they’re not that far removed from real life.

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Gravity stars Sandra Bullock as engineer Dr. Ryan Stone and George Clooney as veteran astronaut Matt Kowalsky
Gravity stars Sandra Bullock as engineer Dr. Ryan Stone and George Clooney as veteran astronaut Matt Kowalsky

 

The following is an excerpt from our full interview with Kevin Grazier in issue 17 of All About Space.

What’s Gravity about?

It takes place in some respects in the not too distant past. It’s about the last Hubble servicing mission, and while the astronauts are servicing Hubble we have a catastrophe that leaves them floating in space.

So in the film there’s an explosion caused by debris that maroons the two astronauts?

There’s a shower of debris, yes. A ring of debris. [This relates to the] Kessler syndrome, which is the notion that a rain of debris caused by a satellite being disintegrated or exploded can then impact other satellites in low Earth orbit, creating more and more debris that just leads to a cascade of parts and bits moving at a very high speed.

Grazier ensured the scientific accuracy of the movie by providing details on things like the Soyuz spacecraft and ISS
Grazier ensured the scientific accuracy of the movie by providing details on things like the Soyuz spacecraft and ISS

 

Is this a real threat?

The Kessler syndrome is the foundation on which the movie was based. It’s based on real science, we had a really factual point to base our movie on. I mean, the US space command monitors space junk down to a pretty small size and they have had incidents when they would deflect the orbit of the International Space Station or the Space Shuttle a small amount because they know they’re going to pass too close to debris for comfort. So clearly if you generate a lot of debris, and with space being increasingly crowded, there’s a low probability [of a collision] but certainly it’s something we need to consider, and certainly for the level of believability for a movie I think it’s good enough.

Have there been moments where such an event almost occurred?

I know they’ve deflected both the shuttle and the ISS when there’s been a potential collision, and I also know that in the second Hubble servicing mission they found a hole in Hubble the size of a quarter that was either caused by space debris or a micrometeoroid strike. These things get hit after being in space for a long time, so there are impacts. I mean, it’s a low probability event but when you’re up there long enough low probability events happen.

The two astronauts in Gravity must fight to survive after space junk sends their mission into chaos
The two astronauts in Gravity must fight to survive after space junk sends their mission into chaos

 

Can we prepare for an event like this happening?

Considering what happened to the shuttle I don’t really think there’s anything you can’t prepare for. I have no doubt [NASA] has procedures, there have been procedures for small strikes, but when you get something that puts the shuttle in a spin like that there’s really nothing you can do to stop it. I mean even the RCS [Reaction Control System] thrusters would run empty your fuel tanks before you could control that spin that the impact causes the shuttle to go into in Gravity.

What do you think of the movie?

It looks spectacular. I’ve never seen anything like it. This movie gives the sense that you are there. A lot of people think they want to go into space, but they don’t realise how unforgiving that environment can be.

Gravity is out in cinemas on 4 October in the US and 8 November in the UK.

Images courtesy of Warner Bros. Pictures

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