March 29, 2001

QuestChat with Steve Smith

NASA Ames Research Center, Moffett Field, CA

[ SteveSmith/ARC - 4 - 09:47:59 ]
Hi Everyone!

[ Susan/NASAChatHost - 5 - 09:48:42 ]
Welcome Steve, Thanks for joining us today!

[ SteveSmith/ARC - 8 - 09:53:01 ]
RE: [Nikki] I was wondering if I lived on mars what could I construct entertainment centers out of?
Hi Nikki, well, I think life on Mars would be pretty different. Almost everything you need, you would have to take with you. So you better bring an entertainment center with you. Imagine not being able to get new CD's except once every two years! We are working very hard to find out if there is water that can be harvested on Mars. If we have water, and solar power, we can make oxygen, and grow plants for food, I think that is so important that if we can't do it, we better not go. Maybe you will so lucky that you get to visit Mars someday!

[ SteveSmith/ARC - 10 - 10:00:01 ]
Today we can talk about everything that is needed to make an airplane fly, on Earth or on Mars or even Venus. The new Web site for planetary flight, has lots of information. Sorry its not super-fancy with lots of color pictures yet - we will keep working on it to make it look cool, but for now, there is a great deal of good info there. I especially like the links to the little airfoil cartoons in the atmospheric flight>lift section. Check it out! At the end of all the great information, there is a design project where you get to pick the way your Mars Airplane should look. It will tell you how well it flies. If you have any questions about how to make the design project work, or about how the answers are computed, we can talk about that too. This is going to be fun!

[ SteveSmith/ARC - 11 - 10:02:34 ]
RE: [Susan/NASAChatHost] What are the major differences for flight on Mars Steve?
The biggest difference is that the atmospheric pressure is very low, only 1% of Earth sea level pressure. That makes it much harder to get the wings to make lift. It takes bigger wings, and you have to fly much faster to get the same amount of lift. The gravity is less, only about 1/3. That helps, because it means you need only 1/3 the lift to fly. Remember the balance of the 4 forces? Also, since there is no oxygen, you can't make a jet engine or a piston engine run unless you supply both fuel and oxygen.

[ SteveSmith/ARC - 13 - 10:10:39 ]
RE: [Susan/NASAChatHost] I guess we are lucky to have Earths' atmosphere and gravity so we can fly around our world easily.
Yes, airplanes are amazing. I recently had to fly to Burbank from San Jose for a business meeting. I was wondering about whether I would use more gas if I drove my car, or more fuel flying the airplane. I have a small car that gets good gas mileage, and even so, it would take 10 gallons of gas to drive there. But on the jet, I worked out that it only took 6.5 gallons of fuel to fly me there. And it took less than an hour, instead of 5 hours.

[ SteveSmith/ARC - 19 - 10:19:24
[ Susan/NASAChatHost - 15 - 10:14:15 ]
Yesterday I had an email from Bolivia, the atmosphere is very thin there in the high mountains. The writer suggested his solar powered model planes would be good designs for a Mars plane. What do you think?
Well, solar power on Mars is interesting. Because it is twice as far away from the Sun as Earth, it only gets 1/4 as much sunlight. But because the atmosphere is so thin, most all the sunlight that gets there goes through to the surface. On Earth, most of the sunlight gets reflected or absorbed, and a small amount gets through to the surface. I'm not sure of the percentage. To fly on Mars, the wings need to be big, so there is lots of space to put solar cells. But it takes quite a bit more power to fly because the speeds are so much faster. Solar-powered airplanes on Earth usually fly very slowly.

RE: [SteveSmith/ARC] Sometimes people ask about flying balloons on Mars. We could talk about that a little bit. The section on buoyancy in the planetary Web site has a fun little applet that lets you see how big a balloon would be needed to carry a certain amount of weight on earth or on mars.
[ Susan/NASAChatHost - 16 - 10:15:26 ] yes how does the buoyant force on Mars compare to Earth's buoyancy?
The buoyancy depends on the density of the atmosphere. Thats why it is so easy to float things on water, because water has a high density. Since Mars atmosphere has such low density, it takes a very, very, very big balloon. The applet uses a red background for the Mars balloon to give the idea of the Mars atmosphere, and a green background to give the idea of being on Earth.

[ SteveSmith/ARC - 24 - 10:30:14 ]
RE: [Susan/NASAChatHost] Steve can we really fly in space?
Well, it depends on what you mean by "fly" doesn't it? We talk about non-atmospheric flight, or space flight, so yes, we can do that. But we cant use wings. We need rockets. When you are in orbit around a planet, you are falling because of gravity. If you go fast, you get a centrifugal force that balances gravity. Its like the tension in a string if you whirl a rock around you on the end of a string. The tension in the string is the force that pulls the rock into a curved, circular path instead of going straight. In the case of an orbit, gravity is the tension force that causes the path of the spacecraft to curve so it turns in a circle. Its fun to study how you can leave the orbit from one planet and fly to another planet. It takes a lot of thrust to break away from the gravity of Earth.

[ SteveSmith/ARC - 25 - 10:33:45 ]
RE: [Susan/NASAChatHost] Why do Mars scientists want to send a plane to Mars someday?
Sending a plane to Mars would give us a chance to look around over a big area, but still get a close-up look. If we send a lander probe to Mars, we pretty much get to see what is right there where we land. We can use a little rover to go explore a little, but not much. If we send surveyor satellites, we get to look at a lot of Mars surface, but from pretty far away, in orbit. An airplane is a perfect in-between solution. We can probably explore a few hundred miles of surface terrain, but we can fly close to the surface and get very detailed close-up pictures. We can also measure the gases in the atmosphere up off the surface. And we can measure magnetic fields and other things like that.

[ SteveSmith/ARC - 27 - 10:43:50 ]
RE: [Susan/NASAChatHost] Which other planets would be suited for flight?
Well, it takes an atmosphere to fly an airplane, so Mars is OK, and Venus would be fine. Venus has other difficulties because it is so hot and there is so much radiation. Really hostile. Jupiter might be OK, but again, the atmosphere is kind of hostile. And very windy! One fun thing would be to think about sending a submarine to Europa. Europa has a very thick Ice crust, but we think it has a liquid ocean underneath. A submarine is basically an airplane that flies under water. Its kind of a good combination of everything we have talked about, because they use ballast tanks to balance the buoyancy, and then wings to maneuver.

[ SteveSmith/ARC - 28 - 10:44:13 ]
Bye everyone!

[ Susan/NASAChatHost - 29 - 11:21:30 ]
RE: [SteveSmith/ARC] Bye everyone!
Goodbye Steve! Thanks for your great answers! I learned a lot.