The many challenges of getting to Mars

12 October 2015

Interview with

Dr Paul Meacham, Airbus Defence

This month, The Naked Scientists have launched a series of programmes that will Bruno, the ExoMars Roverprobe what it's going to take to send people to Mars. This week it's all about the journey - how we'll get there. To rocket engineers, just the idea of transporting humans to Mars is a serious headache. Compared to rovers or other inert satellites and probes, humans are highly unpredictable, needy and fragile. Radiation is our body's kryptonite; microgravity renders the bones thin and weak and if you broke a leg, it could take months to fix. These are just a few of the hundreds of problems scientists are grappling with when considering how they might send people to the rocky red planet. Graihagh Jackson ventured to the 'Mars Yard' at Airbus Defence to meet Paul Meacham to uncover exactly what we're up against...

Paul - Mars is not the easiest place to get to. It's actually very demanding. Even just getting off the surface of the Earth is difficult because our gravity, it doesn't feel very strong to us. But it is an incredible force to overcome.

Graihagh - And then getting there I imagine is what, 9 months?

Paul - It is a very long time, yes. Nine months in cruise and of course, during that whole time, you're away from the Earth's protective layer. So, you're subject to the full elements of space. It's quite tricky to overcome that.

Graihagh - You've got a big job on your hands then.

Paul - We certainly do and that's why facilities like the Mars Yard are so important because it allows us to practice everything we're going to need to worry about when we get to Mars on Earth.

Graihagh - This is the weirdest place I've ever been. I don't know quite how to describe it.

Lost for words I was, but imagine a giant sand pit filled with bright orange sand and a mixture of real rocks and polystyrene boulders taped to the walls were vistas of Mars. Bar the lack of weightlessness, the scorching effects of radiation, and the bountiful levels of oxygen, I did feel like I was traipsing around Mars. This is the Mars Yard and no, it isn't a film set. It's where scientists like Paul test out prototypes of the ExoMars rover which will be sent to the red planet in 2018 for more scientific tests. The latest prototype is rather fondly referred to as Bruno.

Paul - Bruno has on him all the sensors the real rover will need to drive itself autonomously as the cameras and all the sensors in the wheels and that sort of thing. so essentially, we practice driving the rover by itself in this Mars Yard.

Graihagh - Can we take him out for a spin?

Paul - Yes, we certainly can.

Graihagh - Am I allowed to tread on the sand?

Paul - You can.

Graihagh - And away Bruno goes. Bruno looks like a giraffe. Instead of 4 legs, he has 6 wheels and the wheels resemble the sort of things you get on tanks. What strikes me is there's a huge number of things to consider here and a huge number of things that could potentially go wrong. This is just a rover that's about my height roughly. What about when we're sending humans to Mars?

Paul - You got to think about all the elements that the human is going to have to withstand and try to protect them as much as you can from it. So, one of the easiest examples is the launch phase. So, if you're strapped on top of a rocket, it's not a very pleasant place to be. You are getting blasted with lots of vibrations, lots of soundwaves. So, you've got to build your spacecraft to be able to withstand all those forces and not transmit too many of them to the actual passengers.

Graihagh - How do you test that?

Paul - Essentially, you've just got environmental test facilities. Where you have a big table that shakes the spacecraft. We even have a room where we do acoustic test. So essentially, we stick the spacecraft in there and then we blast it with soundwaves. It's not a particularly pleasant place to be because if you were a person in that room, when we were testing one of our spacecraft, you would be killed.

Graihagh - Death by soundwaves doesn't sound like a nice way to go and that's just the take-off. So, what's next? What else have you got to think about when you get out of the Earth's atmosphere and into space?

Paul - Probably, the main consideration is the radiation environment. As you say, we're leaving the protection of the Earth's atmosphere and you are then subject to the full force of solar wind and cosmic radiation. We're well aware of the effects of a radiation on a human body. It doesn't do nice things and you've got to fly through that for 9 months.

Graihagh - I'm assuming that's a huge concern because I know when in the Apollo missions that something like 3 days in space was the equivalent of 12 chest x-rays.

Paul - That's right. They flew through what we called Van Allen belts which are belts of radiation that surround the Earth. It's particularly a high energy environment. But yes, as you say, that was only 3 days and we're talking 9 months. So, the equivalent dose is much, much higher. And so, we're going to have to think about ways to protect the astronauts from that.

Graihagh - So, we're in space. We're now protected somehow against the radiation. What else are we battling against?

Paul - The next thing to think about is actually keeping your astronauts alive because you got to take everything with them that they're going to need. Most essentially, it's oxygen but oxygen is not a particularly pleasant gas. It's extremely flammable so you got to think about how you're going to store that very carefully. The famous Apollo 13 mission was caused by an exploding oxygen tank and it caused serious problems. At least in that case, they had half a chance of going back to Earth whereas if you're halfway to Mars and that happens, you'd have no chance of return at all.

Graihagh - If we do eventually overcome all these perils, what have we got to worry about when we're coming into the surface of landing?

Paul - Primarily, it's going to be the temperature range we're going to be experiencing. So, we have to qualify most things on the outside of our rover the temperatures between minus 130 degrees centigrade up to about 55. So, you're going to have to create an environment which is around room temperature and can withstand these massive temperature extremes we see on the planet and that's not easy to do.

Graihagh - No, quite. Do you have faith in your colleagues to engineer something clever that can do all these incredible things?

Paul - Yes, because I think we'd use something which is not dissimilar from what we use on the inside of the rover. The rover's main structure is called a bath tub and it has this space equivalent of double glazing in order to create a thermal barrier through which heat can't get in and heat can't get out. And then when you do that, you can create quite a habitable microenvironment within that cocoon.

Graihagh - So astronauts are going to be living in bathtubs.

Paul - Well I shouldn't have called it a bath tub should I. That's what you refer to the main structure of the rover.

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