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How to Build a Rover
By Salvatore Domenick Desiano

On Mars Time, the Ice Cream Is Free

Scientists working with NASA's rovers on Mars have their own time zone.

Mars spins more slowly that Earth, so the sun rises every 24 hours and 40 minutes. Since Spirit and Opportunity use energy from the sun to work, NASA scientists working with the rovers need to be up during the Martian daytime.

Every day, these scientists wake up 40 minutes later than they did the day before. This is fun for a while. A week into the project, they don't have to get to work until noon.

As time goes on, though, it gets worse. After two weeks, they have to sleep until 4 p.m. Many put shades on the windows so they can sleep while the sun is out. After three weeks, they have to wake up at 9 p.m. By the time they wake up, their families and friends are asleep!

NASA does everything it can to make the schedule bearable, like having unlimited ice cream in the rooms where they work. But most scientists can only work on "Mars Time" for a few weeks at a time. It isn't easy to take care of a rover that lives on Mars.

If you want to get an idea of what it's like living on Mars time, click here and download a clock that will tell you what time it is where you are, in England, and where the rovers are.

Caption: Engineers for NASA's Mars Exploaration Rover Mission work to complete assembly and testing on a rover. (Photo: NASA/JPL)
The idea behind a rover is very simple: It's a box with a computer in it, six wheels, and a bunch of cameras attached.

But a rover itself is not so simple. Hundreds of people worked in teams to design the rovers, build rockets to propel them into space, make airbags to protect them from a bumpy landing, write programs to control their wheels and cameras, and find an interesting spot to land.

Every day, I go to the NASA Ames Research Center in Mountain View, California, to work on a rover named K-9. You've probably never heard of K-9, since it will never go to Mars. In fact, it rarely leaves my building.

K-9 is kind of a test robot. It's similar to the rovers that will be sent to Mars, and we use them to develop programs and try out scientific instruments before they are put on the actual rover.

We have spent the last five years working on software to control the robot during the long parts of the day when it can't hear from Earth. These programs allow the scientists to give the robot a goal like "go to that rock over there and put your microscope on it." The next time the robot talks to Earth, it will have carried out those tasks and automatically sent back pictures of what it found.

Spirit and Opportunity

In the last few months before the robot is launched, it is sent to NASA's Kennedy Space Center in Florida. The engineers there put on the finishing touches and load it into the rocket for launch. On June 10, 2003, Spirit was launched, and on July 7, 2003, Opportunity was launched on its trip to Mars. The trip takes six months. Scientists don't want to waste those six months, so the robots are launched before the programs are all done.

Last January, six years after we started, the rovers landed on Mars. We sent them their control programs, and they rolled off the landers and into the Martian distance. To many people, that's when the adventure began. But for those of us here at NASA who have been working on the rovers for years, that was one big step in a long journey.

Salvatore Domenick Desiano is a research scientist working at the NASA Ames Research Center.