Kim Ward, Rutherford Appleton Laboratory
Chris - Controlling a Mars rover is a bit like using a radio controlled car albeit a very expensive one and it is very, very expensive when things also go wrong. In fact, the Curiosity mission that weíve been hearing about is costing about 1 million pounds for every day that is spent operating on the Martian surface. Now this is partly because it can take up to a day to send each cycle of commands from Earth to Mars based on what the rover has done or found in the meantime. The mission planners therefore have to wait for the satellites that transmit the signals to be within sight of each other and the rover for the messages to go back and forth. But what about if we could identify sights of interest and then have the rovers find their own way there and do their own science?
The European Space Agencyís StarTiger Seeker project, based at the UKís STFC Rutherford Appleton Laboratories, is trying to do this with an autonomous guidance system for rovers. And to explain more, the head of the Space Engineering and Technology division at RAL Space, Kim Ward is with us. So first of all, how will the Seeker project actually deliver? What will it do? How will it work?
Kim - The intent is to ignore two problems. Namely, we didnít have to worry about power or locomotion. The challenge that we were set by this StarTiger programme was to see if we could move autonomously, so without any interaction from the ground over distances of 2 km on 3 consecutive days. So the challenge was to move 6 km in total without any interaction from the ground. This is the sort of thing that had never been done before. The early NASA rovers, Spirit and Opportunity. One of them only travelled 8 km or something in 8 years and the other, 21 km in 8 years. Now we were trying to get over that problem of waiting for commands by just allowing the rover to make its own decisions to do with navigation. So to figure out where itís going.
Chris - I'm surprised that this problem hasnít really already been solved because there are various initiatives. There's the DARPA challenge in the US which is getting vehicles to drive themselves around really quite tricky courses. So there must obviously be a more fundamental problem involving, actually getting these rovers to explore for themselves. What is that?
Kim - You're right. The DARPA challenges are doing this type of thing with large vehicles, but some of the problems that we have on Mars and other bodies like that is that there are very features. Itís a very hostile terrain. You might have to drive around hazards, rocks and things. There might be poor areas of quicksand or something like that you need to avoid. In order to do these things autonomously it's something that is beyond what's been done by DARPA challenges and so on. Plus, with the DARPA challenges, you have absolutely limitless resources whereas what we were doing with this experiment, at least as regard to the sensors, was to equip ourselves much as we would on Mars. So we didnít have ground penetrating radars and we didnít have some of the lidars and things that you might have for some of the vehicles you're speaking about.
Chris - So how did you solve the problem? Does it work?
Kim - The only sensor that was really needed was a pair of stereo cameras and from those, you build up a 3-dimensional map of your surroundings. And then you have other software called path-planning software that says, based on what I can see of these rocks, and I know I've got to get over to that one over there so Iíll have to go around this rock and do this, and these sorts of things. So, it was all done completely using cameras. Otherwise, the fancy name is visual odometry. Thatís the only technique that was used. We had a secondary objective which was by the way, when you're doing this autonomously, could you notice anything on the way that might be of interest to scientists later? Now that side of it, we didnít manage quite to complete. It was enough of a challenge for just the basic primary objective we had of getting from A to B.
Chris - In other words, you can't go to Mars to test this out yet. So how do you test whether or not itíll work?
Kim - Well, you look for something thatís fairly close to Mars-like terrain and there are a few deserts in Europe and in North Africa, Morocco is quite well-known for some of its Mars-like terrain. But it has some other problems. At the time of year that we wanted to go, namely in June/July time, itís just too hot to exist almost and all the computer and support equipment gets in trouble. You need security guards and that sort of thing if you want to retain your equipment overnight. So, we found that the Atacama desert in Chile, where there's quite a lot of infrastructure to support it, in particular, we were based at the Paranal Observatory where there's workshops, where there's also a nice hotel. Itís the one that was used in the James Bond film, Quantum Solace.
So, the infrastructure is there, but within range of that, you can get out into the most incredibly barren terrain Ė there's just no animals, there's not even any birds over that sort of area, and it almost never rains. And the rock structures and so on are very, very like the sort of thing that we would see on Mars. So, it was an excellent place to do this work.
Chris - And, did it work when you tested it?
Kim - Yeah, we were there for 3 weeks and it was really only on the last day that we could jump from the chandeliers when on the last day, they actually went 5 km autonomously. And therefore, on the basis of that, the European Space Agency has pronounced the project a great success, albeit, itís the first stage really in the series of things that will hopefully happen in the future.
Chris - Kim, congratulations and thank you very much for joining us to talk about it. That was STFCís Kim Ward.
Part of the show Curious about Mars... from the 5th Aug 2012