Page last updated at 09:17 GMT, Friday, 25 September 2009 10:17 UK

European Mars rover's 'eye test'

By Jason Palmer
Science and technology reporter, BBC News


The sandy quarry in Bedfordshire has red sand like Mars

A quarry in the south of England has been the site of an "eye test" for Europe's planned rover mission ExoMars.

The quarry - chosen for its similarity to Martian terrain - saw cameras and image processing software tested on the ExoMars prototype rover Bridget.

The rover will be equipped with a raft of cameras and the aim is to integrate them and the data they will send back.

The technology developed for the mission has applications not only in space science but also here on Earth.

The eventual rover will have a pair of front-mounted navigation cameras and a quartet of cameras at its corners for hazard avoidance.

It will also have a pair of scientific cameras that give it stereoscopic vision and thus depth perception, as well as a high-resolution camera for zooming in on areas of interest.

ExoMars eye test
You can become almost like a field geologist, in the field on Mars
Lester Waugh
EADS Astrium

The wide-angle scientific cameras are equipped with filter wheels, which limit the light that reaches them to specific wavelengths.

Measuring the sunlight reflected off Martian terrain in these specific bands gives information on the chemical makeup of whatever is in the field of view.

The aim of the EU PRoVisG (Planetary Robotics Vision Ground Processing) project is to stitch together all of the information from the cameras, ensuring for example that the scientific results are tagged to the location at which they were taken and that the navigation cameras' views are assembled into a virtual, 3D representation of the rover's environment.

Also at issue is how to get that data sent back to Earth; there is a finite amount of information the rover will be able to send back in a day.

What is more, the data's trip from Mars can take 20 minutes, so for mission-critical movements, it is important to be able to bounce data and instructions back and forth as quickly as possible.

As a result, the cameras' resolution has been deliberately limited so that the image files they send back are not too unwieldy, and part of the project concerns itself with compacting and minimising the total amount of data the rover must send.


While much of the technology to acquire images, send them wirelessly, and stitch them into a sensible whole already exists, getting similar systems onto the surface of Mars is a whole different matter.

"Imagine you have a terrestrial, state-of-the-art computer. We couldn't send it into space because it would never survive," said Lester Waugh, lead engineer for EADS Astrium, the space firm that led the development of Bridget and coordinates the UK efforts of PRoVisG.

Curiosity and skycrane (Nasa)
Now likely to leave Earth in 2018; primary aim is to search for life
Current proposal is to use a US Atlas rocket to launch ExoMars
US also to look after the rover's entry, descent and landing
Hardware likely to be the same as for US 2013 rover, Curiosity
ExoMars would be targeted at key methane hotspots on the planet
It will have the capacity to drill 2m into the Martian ground
Esa states still have to sign off the plan and a budget

He explained that anything sent to Mars has to withstand the extreme vibrations of launch, space temperature extremes of both hot and cold, and constant bombardment from cosmic rays. Engineering around those constraints and then testing equipment to exacting standards - making it "space qualified" - takes a great deal of time, so space-worthy technology necessarily lags behind the less robust terrestrial version.

The project is also concerned with developing tools to display and make use of the data from the rover.

"From the images, we can generate 3D elevation maps - 3D representations that you can actually explore," Dr Waugh explained.

"Once you've created that model you can use all the surface textures you've gained from the imagery, and you've got an environment that people can go and explore. You can become almost like a field geologist, in the field on Mars."

The new visualisation tools can also be used to inform future, manned missions to Mars.

"It's a bit like Google street view: you can go down to street level and explore the environment so that when you drive into the place, you know what's going on there.

"It's the same for astronauts - if you want them to know what the environment is like, then give them a 3D virtual reality experience. This helps a lot with their planning."

For more Earth-based applications, Dr Waugh said that robust imaging technology developed for ExoMars could see use in rovers used for volcanic science or in nuclear sites, where temperature and radiation extremes limit typical robotic technology.

He added that the 3D visualisation approaches could be "great fun" if used for gaming.

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