How to drive a robot on Mars
GREENBELT, United States: Some 78 million miles (126 million kilometres) from Earth, alone on the immense and frigid Red Planet, a robot the size of a small 4x4 wakes up just after sunrise. And just as it has every day for the past six years, it awaits its instructions.
Around 9:30 Mars time, a message arrives from California, where it was sent 15 minutes earlier.
“Drive forward 10 meters, turn to an azimuth of 45 degrees, now turn on your autonomous capabilities and drive.”
The Curiosity rover executes the commands, moving slowly to its designated position, at a maximum speed of 35 to 110 metres per hour.
Its batteries and other configurations limit its daily drive span to around 100 metres. The most Curiosity has rolled on Mars in a day is 220 metres.
Once it arrives, its 17 cameras take shots of its environs.
Its laser zaps rocks. Other tools on board drill into a particularly interesting rock to study small samples.
Around 5pm Martian time, it will wait for one of Nasa’s three satellites orbiting the planet to pass overhead.
Curiosity will then send several hundred megabytes of scientific data via large ground antennae to its human masters on Earth.
On the ground floor of building 34 at Nasa’s Goddard Space Flight Center in Greenbelt, Maryland, scientists pore over Curiosity’s data every day at 1pm, in a large windowless room full of scientific instruments and computers.
The scientists are looking for any indication of life on Mars.
Inside Curiosity lies a “marvel of miniaturization,” says Charles Malespin, the deputy principal investigator for Sample Analysis at Mars (SAM), a chemist’s lab the size of a microwave oven.
“It’s the most complicated instrument Nasa has ever sent to another planet,” said Malespin, who has devoted his professional life to the project since 2006.
SAM analyses samples of Martian soil by heating them in an oven that reaches 1,800 Fahrenheit.
The hot rocks release gas, which is separated and analyzed by instruments that offer a sample “fingerprint.”
At Goddard, Maeva Millan, a French postdoctoral researcher, compares this chemical fingerprint to experiments carried out on known molecules.
When they look similar, she can say, “Ah, that’s the right molecule.”
It is thanks to SAM that researchers know there are complex organic molecules on Mars.
And SAM has helped scientists learn that the Martian surface — geologically speaking — is far younger than previously thought.
The Mars drivers’ main job is to write the sequence of commands for the rover to follow the next sol, or “day” on Mars, which lasts 24 hours and nearly 40 minutes. There is no joystick, and no realtime communication with the robotic vehicle.
There is a delay whenever drivers realize something has gone wrong, whether it’s Opportunity getting buried by a Martian dust storm earlier this year, or one of Curiosity’s wheels getting pierced by a sharp rock.
Or the breakdown of Curiosity’s drilling machine, which happened at the beginning of this year and took a few months to resolve.
“We haven’t been to any of these places before,” said Hartman. – AFP