May 16, 2008
Europeans Continue Work on Mars Rover
Engineers in Europe continue to develop a billion-euro project to put a robotic rover on the surface of Mars.
A sophisticated new vehicle prototype has been developed as they work towards the flagship ExoMars mission.
ExoMars is scheduled to leave Earth in 2013 and land on the fourth planet a year later. The project has yet to receive final sign-off from space ministers.
The ExoMars project will carry a suite of instruments across the Martian landscape, looking for signs of past or present life.
The Canadian MDA Corporation developers hope the new prototype will help engineers understand how the real rover will behave when it moves through the rocky terrain.
"This will be the first element that touches the surface of Mars as ExoMars rolls off the lander," said Nadeem Ghafoor, MDA's manager of planetary exploration.
"And when you've decided where you want to go, this is the system that gets you there and gets you over any obstacles on the way," he added.
The eventual flight vehicle will have boxes on the top of the rover that house the current avionics needed to run the rover systems.
MDA was given a list of requirements to work to concerning issues of stability, the type of terrain and soil the vehicle would have to traverse, obstacle heights, mass and power parameters.
The company's engineers were then left to come up with what they thought were the most appropriate solutions.
"Each wheel can turn which allows us to do point turns, rotating about the centre of the rover chassis," said Mike Schmidt, MDA's ExoMars project manager.
"It can do a regular turn like you would do in your car, going around a sweeping bend. And it also allows us what's called crab mode, in which all six wheels turn in the same direction, allowing the vehicle to shuffle sideways like a crab would," he said.
"This provides benefit if you want to get up close to an object to deploy scientific instruments."
The vehicle can also lean one way or another by extending its wheelbase to alter its pose or stance.
"This will help with stability on slopes but also in the deployment of certain instruments or drills that need a certain orientation with respect to the surface," said Schmidt.
Aluminum and stainless steel currently form the basis of the prototype, but to reduce weight, the final rover would probably incorporate titanium and a beryllium alloy to reduce the weight of the system.
The current one-and-a-half-meter-long MDA mechanism is only 76kg. The final flight vehicle will be about 200kg, all systems included, and have to fold up into an extremely tight volume for transport to Mars.
A Swiss-German consortium, led by the Oerlikon and VH&S companies, has produced its own prototype that is being built parallel to MDA's.
The UK arm of EADS Astrium is overseeing the whole process of chassis development. In June, the British outfit will look at both machines to share technical solutions.
Astrium will test both rovers in a "Mars Yard", a facility set up to simulate the Red Planet's landscape. Only one of the teams will be asked to take the design forward.
"At the same time as completing this work, the teams put together bids in response to invitations to tender. We've received those tenders and are currently in the process of evaluating the best one," said Chris Draper, Astrium's ExoMars industrial manager.
"On the basis of that, one or the other will be selected for flight implementation. The next phase will be to qualify the design, to build engineering and qualification models that undergo all sorts of environmental tests - being shaken, and heated up and down, etc."
The ExoMars project has grown over the years.
In 2005, member-state delegations to the European Space Agency (Esa) initially approved a 650m-euro program. Since that time, design reviews have indicated that a better value science return would be achieved through a bigger, more capable rover.
But the cost for this "enhanced baseline" will have to be cleared again by space ministers when they meet in The Hague in November.
Unlike Europe, Canada has special co-operative status within Esa and, as such, the country's space agency and companies are regular participants in Esa projects.
MDA is well paced to assist in the ExoMars effort"”the company provided the space station's robotic arm system, Canadarm2, and its recently installed extension, the Dextre two-armed manipulator.
"It's a really exciting time here and it would be great to take that expertise and all that technology and put it into the locomotion system on the ExoMars rover," said Nadeem Ghafoor.
On the Net: