The Courier & Advertiser (Angus and Dundee)

The truth behind Gravity

How realistic was the Hollywood blockbuste­r Gravity? Ahead of a St Andrews University lecture, Michael Alexander meets a former NASA astronaut and a space scientist to hear about the increasing risk of being hit by debris in space for real.

- The public lecture – An Evening with NASA – The Truth Behind Gravity, is tonight from 7pm to 8.30pm at the Buchanan Lecture Theatre, Union Street, St Andrews. Entry is free but attendees should pre-register by emailing: schoo

It was an enthrallin­g and beautifull­y shot blockbuste­r of a movie which followed the exploits of two astronauts on a mission for survival after the destructio­n of their space shuttle in a catastroph­ic debris collision. When Alfonso Cuarón’s 3D space thriller Gravity was released at cinemas in November 2013, it was widely praised for its realistic portrayal of life in space.

But how do real NASA scientists view the accuracy of the film that starred George Clooney and Sandra Bullock?

The realism of the movie will be explored by former NASA space shuttle astronaut Rick Hieb and NASA orbital debris program scientist Dr Sue Lederer when they give a public lecture at St Andrews University this evening.

The Americans have been in Fife this week working with primary children on a Space School programme.

In an interview with The Courier at St Andrews University, the scientists revealed that while many parts of the film such as the depiction of the Hubble Space Telescope are well done, other aspects such as orbital mechanics – how things move in space – do not stand up to scientific scrutiny.

Dr Lederer, 45,who specialise­s in tracking orbiting debris from exploded spacecraft, said: “There are pieces in the movie that are much more grandiose because the film makers wanted to make it exciting. There are pieces in the movie that are actually worse in reality in space than they are shown in the movie. So we are going to talk about what the reality is, what’s true and what’s false.”

Mr Hieb, 60, who spent over 750 hours in space during three space shuttle missions in the 1990s, added: “It’s a fun movie. I know they have to make it more dramatic to entertain audiences. But the net result is that people do not have a clue about what’s really right or wrong. That’s the frustratin­g part to me.

“On the other hand another film, The Martian is pretty good.”

Dr Lederer was part of an internatio­nal team of scientists who studied Comet Tempel 1 – the target of the Deep Impact Spacecraft mission, which successful­ly impacted the surface.

She also recently helped discover three Earth-sized planets around a very small red star called TRAPPIST-1.

Her main role, however, is helping track orbital debris around the Earth, like pieces of spacecraft that have exploded or collided with other objects in space.

There are millions of man-made pieces of debris orbiting Earth ranging in size from spent rockets to micronsize­d pieces of dust. But Dr Lederer said the US Department of Defence is only tracking around 22,000 because most are too small to detect.

The real issue is the speed at which these objects are travelling.

She said: “Imagine the size of a bullet. A sniper rifle shoots at around one kilometre per second. At the level where the Internatio­nal Space Station is orbiting (400km) objects move on average 10km per second. So even if it’s something as tiny as a grain of sand, imagine a grain of sand hitting you at a speed 10 times faster than a sniper rifle.”

Dr Lederer explained that anything that’s collided, shed off or exploded in orbit will create a field of debris and a self-sustaining cascading event known as Kessler Syndrome, which can produce at least 200,000 pieces of debris from one single impact.

The risk to orbiting spacecraft or satellites is very real with several satellites knocked out in recent years.

She added: “It’s a serious enough risk that anywhere between one to 10 times per year the ISS will manoeuvre and do a slightly different orbit to avoid being hit by space debris.

“And there are situations where the astronauts go into the Soyuz capsule in a safe zone so that if the space station does get hit and the atmosphere gets released into space, they are immediatel­y ready to come home. This would usually be because there’s a particular piece of debris that they could intercept.”

Mr Hieb said that during shuttle missions it was part of morning routine to inspect the triple layer reinforced windows for tiny yet visible impact craters, usually caused by high velocity specks of dust or paint. Damage was found on most missions and this would be photograph­ed and scrutinise­d for repair back at home.

“In a space suit when you are outside,” he added, “you are just kind of counting on the big sky theory, because there’s a lot of room up there.

“But when objects are going so fast, if you get hit by something it’s a really bad day.

“Something the size of a marble could go through a crew member like it didn’t even notice you were there.”

 ??  ?? Former NASA Astronaugh­t Rick Hieb, top right, and NASA Dr Sue Lederer visit pupils from Fife Primary Schools who have almost completed a “Space School”. The pupils learned about the science and processes relating to space while on a visit to St Andrews...
Former NASA Astronaugh­t Rick Hieb, top right, and NASA Dr Sue Lederer visit pupils from Fife Primary Schools who have almost completed a “Space School”. The pupils learned about the science and processes relating to space while on a visit to St Andrews...
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Pictures: Steven Brown.
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