What's more dangerous - landing or taking off in a spacecraft?

Chris put this question to Space Boffin Richard Hollingham...

“In a space mission, which is actually more dangerous - taking off from Earth, or landing back on Earth safely?”

Richard - Actually, if you look at the statistics on this during launch only one crew has died - that was the Challenger disaster in 1986 where seven died. With the Soyuz, which is the Russian spacecraft, in 1983 two crew were ejected on the escape system. So only seven people have died on launch but still, seven people too many.

If we look at landings, I think they’re more dangerous. So you look at the first Soyuz capsule, the cosmonaut died because his parachute became tangled. The Columbia disaster in 2003 where seven crew died on the way back to Earth. And then in 1971, three crew died on Soyuz 11. So we’ve had 11 astronauts die re-entering the atmosphere.

If you think about that, actually it makes a lot of sense because escape systems are normally built into spacecraft. One of the big flaws of the space shuttle was it didn’t have an escape system. So the first space shuttle that flew into space had ejector seats, but after that there was no provision to get the crew out if something went wrong, whereas the Soyuz has that. So if something goes wrong on the launchpad, the rocket blows up, the escape system will eject and it’s proved that works. It’s the same with previous American missions as well.

But you look at the return to Earth - well, there’s so much that could go wrong with the spacecraft. There could be flaws in the spacecraft, something could go wrong like the parachute getting tangled, a faulty component or there could have been damage. With the space shuttle Columbia, there was damage during launch to the spacecraft which meant it burnt up on the way down.

但两者都是真的dangerous!

Chris - Kate?

Kate - You mentioned the worst case scenario - people dying, but how about just getting injured?

Richard - It’s interesting with the Soyuz because I’ve interviewed a few astronauts about this. It’s been variously described as going over Niagara Falls in a barrel, or going over Niagara Falls in a barrel on fire followed by a car crash, because it is pretty awful. Certainly people have become injured in the Soyuz. There have almost certainly been some broken limbs and damage done in the Soyuz coming back to Earth but almost everyone has walked away from the spacecraft.

Chris - I was in Perth in Western Australia, the week before last, with Steve Robinson who’s been an astronaut on a number of shuttle missions and done a number of spacewalks. He showed me a picture of what your ambulance is like if you need an emergency trip home and told me what the G forces are like, and to say that a rollercoaster ride is exhilarating would be really quite an understatement! Because you’ve got someone who’s unwell injured in some way and then and gets this 6 G, 7 G ride back home to Earth and then crash lands down with a bump. It sounds horrendous.

Richard - Yeah. 230 metres per second in the speed! If you look at the medicine on the space station, you’ve basically got about the same degree of medical help as you would aside a public swimming pool. That sort of degree of first aid.

Chris - You don’t want to get sick up there do you?

Richard - No. If you get really sick up there you get bundled into a Soyuz and sent back to Earth.