Robot Explorers

Ken Tapping, October 10, 2012

In the sky this week…

  • Mars is low in the Southwest after sunset.
  • Jupiter rises around 10 p.m. and Venus around 4 a.m.
  • The Moon will be New on the 15th.

Although having a human explorer on the spot is the quickest way to find things out, this is not always feasible, affordable, or safe. That is where robot explorers come in.  Losing one of them is obviously not desirable, but no lives are endangered, no life support is needed, and there is no need to build in a means of getting home.

Our first explorers were satellites like Alouette, which orbited the Earth, ran sensors and sent back data until their batteries or solar cells failed, or some other problem stopped them working. Then there were spacecraft like Lunar Surveyor, which landed on the Moon, the two Viking landers on Mars, or the various spacecraft that soft-landed on Venus, where they sent data for 20 minutes or so before being fried by the high temperatures. These did not have the power to move around. Our view was confined to one location.

However, the ideal explorer is something that can trundle around and explore different locations. One of the earliest ones of these was Lunokhod, which was landed on the surface of the Moon by the Soviet Union. It looked like a wheeled bathtub with an open lid, which contained the solar cells providing its power.  Unfortunately, even with a mobile lander on the Moon, which lies only about 384,000 km away, we encountered the beginning of a problem. Radio waves travel at the speed of light, just under 300,000 km a second. That means a radio signal takes about a second and a quarter to get from the Moon to the Earth or vice versa. In your driving seat on Earth, your view through the windshield is over a second old, and if you put your foot on the brake pedal, the brakes go on over a second later.  The only safe way to avoid a crash or getting stuck was to drive Lunokhod very slowly.

If we have rovers trundling around on the surface of Mars, a robot submarine exploring the ice-covered oceans of Europa, a robot paddleboat sailing the oceans of Titan, or an instrumented aircraft flying the atmosphere of Jupiter, the remote control idea becomes completely unworkable. Signals from the explorers will take tens of minutes to hours to reach us; our controlling signals just as long to get back to the vehicles, and then just as long again for us to see what happened. The only solution is to make our explorers robots, able to make decisions for themselves.  We will tell them where we want them to go, and then leave the robots themselves to plan the route and get to their destination without getting stuck or colliding with something on the way.

Fortunately, great strides are being made in computer power, machine intelligence and imaging. Robots can now recognize obstacles and plan their routes to avoid them, and when they reach their destinations, can carry out elaborate observations and experiments. In a decade or two our robots will be far smarter. Most of our pioneers in the exploration of space will be robots. They are no substitute for people, but they can be the pathfinders and are happy with journeys taking many years. Robots will continue to explore the outer Solar System and will be our initial emissaries to the stars. Moreover, it is nice to know that robotics is something that Canada is rather good at.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9.

Telephone: 250-497-2300
Fax: 250-497-2355
E-mail: ken.tapping@nrc-cnrc.gc.ca

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