How do we get back to earth from the moon?

07 February 2017

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Question

Tshepo - How do they get spacecraft back to earth from the moon? For example, is there a runway on the moon for the Apollo to fly back? How do you make the return to earth safe?

Answer

Chris Smith asked space expert Richard Hollingham to answer Tsheppo's query...

Richard - Well, it’s actually quite an interesting question this. Apollo had two engines so it could go down on the Moon. The last Apollo was in 1972. It could go down onto the Moon, it used the engine to slow itself down and get down onto the surface. Really hairy - if you listen to those communications between mission control and the astronaut you can hear all these things going wrong and then it’s down and it’s fine.

Neil Armstrong, the first lunar landing in 1969, I think it had 11 seconds left of fuel to get down without crashing, but this was an argument for cancelling Apollo. It was meant to run until at least 20 and the last Apollo mission was Apollo 17, so 11 to 17 and 13 didn’t land on the Moon. Was it was a single point failure of getting back. So it was a separate engine to get it off. Those odd looking lunar landers you see, the top part had a separate engine, you press a button and it fires or it doesn’t fire. If it doesn’t fire your astronauts are stuck on the Moon and there is absolutely no way they can get back.

What’s also interesting about this is that the Soviet Union, who never managed to land an astronaut on the Moon or a cosmonaut as they would say, actually had a much better way of doing it. So they had a lander but it would only fit one cosmonaut in. Unfortunately, their rocket was rubbish and the never got anywhere near the Moon but they had their lander. It would have one cosmonaut, get out of the lander and get on the Moon’s surface. If there was a fault with that lander and he couldn’t get back so they had the same engine system, they were actually landing another lander a couple of kilometres away and there was a rover he could use to get to the other lander to get back off the surface.

Chris - Did that land independently with no-one on that one?

Richard - Yeah. So that landed independently with no-one on it. He could use this robotic rover to hitch a lift to get to the other lander and get off the Moon. When we go back to the Moon and when we go to Mars, it’s something to seriously think about. It’s not just getting there. Getting there is relatively straightforward, we know how to do that. It’s getting back and it’s always getting back

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