Questions
How did the NASA team plan to slow down the rovers as they fell toward the surface of Mars?
How did the scientists solve the problem of airbags breaking?
Why is this story named
“A Soft Landing on Mars?”
A Soft Landing on Mars
Imagine that you work on the Mars rover team. Your job is to figure out how to get Spirit and Opportunity to land safely on Mars.
As the rovers come close to Mars, they will be speeding along at 12,000 miles per hour. If they try to land at that speed, they will crash. You have to figure out how to keep the rovers safe during the landing. Do you have any ideas about how to do that? Keep in mind that the rovers cost 800 million dollars to build. If you make a mistake, all that money will be lost — along with years of work.
In this article, you'll find out how the NASA team tried to keep the rovers safe during the landing on Mars.
Slowing Down the Rovers
Imagine that you are a skydiver jumping out of a plane. At first, you drop toward the ground at a frightening speed. But before you crash to Earth, a parachute opens and it slows you down so that you can land more gently.
NASA engineers decided that parachutes would be a good idea for the rovers, too.
Parachutes would slow the rovers down as they fell to the surface of Mars. The engineers had some parachutes made for the rovers. Then they tested the parachutes in a wind tunnel. A wind tunnel is a place where scientists test spacecraft and airplanes. The powerful wind in the tunnel was like the rush of air that would hit the rovers as they were speeding toward Mars.
At first, the parachutes failed the tests. But the engineers tried to stay calm. They made changes and did more tests. At last they had parachutes that worked in the wind tunnel. But would the parachutes work during the landing on Mars?
The engineers had done their best to answer that question, but a wind tunnel on Earth is not the same as a high-speed landing on Mars. The team would have to wait for the landing to find out.
Planning a Soft Landing
The rovers needed more than parachutes to keep them safe as they dropped onto Mars. If everything went well, the rovers would be moving at just 12 miles (19 kilometers) per hour when they hit the ground, but even at that speed they could be crushed if they were not protected.
Today's cars have airbags to protect people during a crash. The NASA engineers decided that they could use airbags for the rovers, too. The airbags would fill up with air like a balloon just before the rovers reached the surface of Mars.
Then the airbags, with the rovers inside, would drop onto the surface. They would bounce along for as much as a mile before they finally came to a stop. If the airbags did their job, the rovers would arrive safely on Mars.
Testing the Airbags
In the past, engineers had used airbags to land smaller spacecraft on Mars, so the rover team expected things to go smoothly when they tested the airbags on the rovers. But they were wrong. During tests on Earth, the airbags split open as they bounced onto the ground. The engineers were shocked to find holes as big as cars in the airbags.
The airbags broke because the rovers were larger and heavier than the other spacecraft that had landed on Mars. The engineers had to find a way to make the airbags stronger.
The team tried many different designs for the airbags, but the bags kept breaking during tests. In the end, the team placed one airbag inside another airbag. These airbags passed the tests. They bounced onto the rocks without getting any holes in them.
When the time came for the landing on Mars, the NASA team waited nervously to see if the parachutes and airbags would work.
Then a signal arrived from Spirit, the first rover to reach Mars. The team members cheered and hugged each other. Spirit had landed safely inside its airbag.
Later, Opportunity also bounced to a safe landing on Mars. Scientists were thrilled. They couldn't go to Mars themselves, but they could see it through the rovers' eyes.