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How Does NASA Drive The Mars Rover?

NASA's Mars Exploration Rover, Opportunity, has extended its robotic arm for studying a light-toned rock target called "Athens."

The discovery of seven new planets that could contain life has kids and adults pretty excited. We can't get to these planets yet but we do have tools to explore planets closer to home.

In this episode, St. Michael's College astronomy professor John O'Meara answers how the Mars rover is driven from back here on earth?

Also in this episode, we head to the Rideau Canal in Ottawa to find out why ice floats and why  some ice is clear and some is not.


"How do they control the rover on Mars back here on earth?" - Sadie, 7, Blacksburg, Va.

We turned to John O'Meara of St. Michael's College for an answer.

Sadie, 7, lives in Blacksburg, Virginia, but was born in Fairbanks, Alaska. She plays violin and piano, loves ballet, telling jokes, reading, math, nature, and is fascinated by space. She wants to work in NASA's Mission Control when she grows up. Her favo
Credit courtesy of parents
Sadie, 7, lives in Blacksburg, Virginia, but was born in Fairbanks, Alaska. She plays violin and piano, loves ballet, telling jokes, reading, math, nature, and is fascinated by space. She wants to work in NASA's Mission Control when she grows up. Her favorite astronaut is Mae Jemison.

"There are two Mars Rovers that we have that are driving around on the surface of Mars. One is called Opportunity, which was part of a set of two rovers that landed over 12 years ago: Spirit and Opportunity. And Opportunity is still driving around. The larger Mars rover is called Curiosity and it's about the size of a small car.

"If we want to be able to send people to Mars we want to know what kind of place we're sending them to, and so the rovers are driving around drilling into rocks, looking for water, looking for other things, trying to understand what Mars was like a long time ago and what it's like today."

"Every single day some people at the Jet Propulsion Laboratory out in Pasadena, California, they upload a set of commands to the rover and they say 'OK Rover, I want you to go over to that rock and drill it' or 'look over at that piece of gravel or dirt out there and we want to see something interesting about it.' And so they will tell the rover to go over to that spot and they will tell the rover to go over that spot in one of two ways: either they just say 'Go over there and you figure it out.' The rover has these hazard cameras on it that are kind of like our eyes. And so they can see in 3-D and figure out where rocks are, how big they are, whether or not they're dangerous. And the rover can figure its way out over there all by itself. It's got that good software inside of it. Or if it's a particularly dangerous way for the rover to go they will upload commands to say 'OK go a few feet and then stop and take a picture and send us the picture and then go a few feet more and send us a picture' and they keep going stop and start and stop and start like that.

"There's no like joystick or anything like that. They type the commands into a computer, that computer then talks to a satellite and that satellite is part of what we call the deep space network. The deep space network sends things off to another satellite that's orbiting around Mars and then that satellite relays the information down to the rover. And this is all really difficult because it takes like 15 minutes for the light to get from the Earth to Mars. And so whenever they tell the rover to move they have to wait a really long time to see whether or not it did.

"That's why we have all these hazard cameras on there and all this software inside of the rover and they had to build similar software into the rover system when it came into Mars because it only takes about seven minutes to go from outside of Mars's atmosphere to landing on the surface of Mars. And it takes a much longer time for the signal to get to us. So the Mars Rover had to land itself. It had to be smart enough to land itself safely and it was really awesome to watch it pull that off."

- John O'Meara

Credit Mel / VPR
The ice on the Rideau Canal in Ottawa is 12 inches thick, and two colors, clear and white. Bruce Devine of the National Capital Commission holds a core sample.

"Why does ice float?" - Benjamin, 5, Philadelphia

"The water is made of many molecules like you imagine small bingo balls all tied up together, so it's very tight. It has something of a weight. But when it freezes those bingo balls separate," explains Bruce Devine of the National Capital Commission, which maintains the Rideau Canal in Ottawa. As those molecules freeze, they separate and become less dense. The lighter ice floats on top of the denser water.

Credit Melody Bodette / VPR
As many as 20,000 people head out on Ottawa's Rideau Canal every day during skating season.

"Why is some ice clear and some is not?" - Caleb, 7, Amherst, Mass.

"We've seen in pictures or some have seen it in life, the icebergs are blue, sort of. So those are old, old ice blocks. The sunshine goes through and it absorbs every color of the sun except the blue and it reflects it. So that's why we see it kind of blue.

"[On the canal] we have two types of colors. You've got clear ice, this is the natural water underneath that has no snow on it. There's no dirt on it, it's very clear. We can see through it." There is also white ice, which is caused by air bubbles. "So it's all squished together, this becomes solid as normal ice. So the tighter this ice, the less bubbles there is, the safer it is to be [on]." If you see gray ice, Devine says this is a mixture of ice that has frozen and thawed so there's a little bit of water that gets trapped into it. "It doesn't freeze very well. So we call it a grey ice that is not a safe ice to be on."

- Bruce Devine, National Capital Commission.

Credit courtesy from parents
Caleb, left, 7, lives with his parents, sister, cat and chickens in Amherst, Mass. He loves skiing, skating, star wars and all things snow. He also loves to do science experiments, which in the winter often involve ice and water. Ben, 5, lives in Philadelphia, PA. He loves science, especially anything having to do with oceans, water and marine biology.

Listen to the full episode for more on the Mars Rover and the Rideau Canal.

Read the full transcript.

Melody is the Contributing Editor for But Why: A Podcast For Curious Kids and the co-author of two But Why books with Jane Lindholm.
Jane Lindholm is the host, executive producer and creator of But Why: A Podcast For Curious Kids. In addition to her work on our international kids show, she produces special projects for Vermont Public. Until March 2021, she was host and editor of the award-winning Vermont Public program Vermont Edition.
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