Selected Articles from the
September 2001 Odyssey

Editor: Terry Hancock

• Robotics Aboard Space Station Alhpa, Steven Bartlett
• "Never Give Up!", Robert Gounley
• The Surf Report, Diane Rhodes

The Surf Report

by Diane Rhodes

Robotics in Action

One of the main problems of exploring our planetary neighbors is that they're too far away. You can scan a planet from the sky, flying over the terrain, but a close up look is tricky. Imaging radar works, but lack of definition in images can lead to errors. And humans can't go, yet. It's still too far, too uncertain for survival. Many missions are being planned, but more study is needed before Spaceman Spiff can go.

So you design a robot to go for you. You try to design one which will fit the requirements as you know them, with a little leeway for what you can't predict. Because the place being explored is so far away, you also need one which can be partially or fully autonomous, able to act independently, or at least programmed to wait for instructions. If your rover has approached a cliff, the time lag in communications will be too long: That cliff on Mars was 10 minutes ago, before you even know about it and your commands won't get back to Rover until 20 minutes after it's over the edge. You wouldn't want to have a rover which couldn't make even the tiniest move without getting instructions from Earth, so the more independent the better. But what if you miscalculated something? You would really want to test it out before you send it out. That's why there's a Mars Yard, a simulated Martian terrain for trying out ideas, located on a former back lot of the Jet Propulsion Laboratory. To learn more about it, go to: http://robotics.jpl.nasa.gov/tasks/scirover/marsyard/homepage.html

Many different designs have been developed, to fit different scenarios. Sojourner was a champ, but she couldn't travel far from the lander, which was needed to communicate with Earth. A more mobile machine will need to carry at least some of that capability on board. Another problem: speed and manueverability. Mars is really bumpy, when it's not flat or vertical. There have been a few related approaches to this: either bigger versions of Sojourner or something completely different, but familiar looking -- the Big Wheel Rover: http://www.jpl.nasa.gov/adv_tech/rovers/bigwheel.htm

An accident with the Big Wheel Rover led to another, slightly off-the-wall but intriguing approach: While testing Big Wheel, one of the wheels came loose and started rolling away. In a light breeze, it managed to go for over a quarter mile before being recaptured, over some pretty rough terrain. That led to something which is being explored now, the Tumbleweed Rover: http://www.cnn.com/2001/TECH/space/08/20/mars.ball/

To watch the video of it in action: http://www.jpl.nasa.gov/videos/technology/tumbleweed_rovers.html

And finally, in case you were wondering "How Many PhDs does it take to move a boulder?": http://robotics.jpl.nasa.gov/tasks/scirover/marsyard/boulder.html

Till next time.

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