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Space Day Challenge 2

Sherri speaking on screen.

Sherri: Hello, all of you out there in World Wide Web land. My name is Sherri Jurls and I'd like to welcome you to the Johnson Space Center here in Houston, Texas. It's really a beautiful center, we are one of ten NASA centers from across the United States that each has a special focus and our focus here is human space flight. We're going to be talking about some aspects of that today. I'd like to show you what a beautiful place Johnson Space Center is if you have never visited us.

Video showing aerial view of Johnson Space Center.

We have about 1,620 acres, hundreds of buildings and about 28,000 employees who all work here together as part of a team to support the human space flight program.

 

Just off to the back of your screen there, you can see over the horizon into the Gulf of Mexico. It's really a beautiful place to visit.

Back to Sherri.

Again, my name is Sherri Jurls and I'll be your host today and we have a very special guest joining us for this design challenge Web cast today, his name is Chris Culbert. Welcome, Chris.

Sherri and Chris shown on the screen.

Chris: Good morning. Thank you.

 

Sherri: Will you please take a moment and share with all of us out here in World Wide Web land what you do.

Chris Culbert speaking on screen.

Chris: I'm the chief of the robotics systems technology branch. My organization's responsible for building some of the advanced technology types of robots and systems that we hope to use in space in the future. We build a lot of very interesting things, Robonaut is one of the ones that you'll probably find information on the Internet right now.

Sherri speaking on screen.

Sherri: Great. Can you give us a little bit of your career path, a little bit of your history. Had you always planned on being in robotics, or tell us a little bit about that.

Back to Chris.

Chris: No. I've been here at the Johnson Space Center for about 20 years now. I started my career as a flight controller. I originally graduated from the University of Arizona with a degree in aerospace engineering which is one of the fields of engineering that applies to building space vehicles, obviously. I started as a flight controller working in the control center with the space shuttle missions, very early space shuttle missions, I've done a wide variety of things since then, building a lot of software, working on computer programs.

 

I worked building portions of the Internet that NASA helped do for 14 years and now I manage a group that builds advanced robots and really cool toys if you like them that way.

Sherri speaking on screen.

Sherri: Can you tell us about a few of those projects, Chris? You mentioned Robonaut being one of them, what other major projects in terms of robots are you guys working on?

Chris speaking on screen.

Chris: Well, our organization handles all the robots for - vehicles that fly in space today, so what everybody calls the big arms, we call them manipulator systems that we use on the shuttle and the space station right now. Our organization does some of the work in planning them and training our astronauts to use those systems. We also build some of the newer robots that we hope to fly in the future. Robonaut is a two-armed humanoid type device.

 

We also have something called Mini-air Cam which is a small, little robot that'll fly around by itself and provide pictures anywhere in the space station that the astronauts need them. We're also working on some simple super rover concepts and ideas to help the humans deploy things on the surface of a planet like Mars or the Moon.

 

Sherri: Well that leads right into what we're talking about today.

Sherri speaking on the screen.

All of the students our here in World Wide Web land, I believe 4th through 8th graders, although I know there are others of you out there who are just from sheer interest participating in this, that this design challenge is in conjunction with Space Day and I know we want to learn more about the solar system and I know you guys chose the design challenge where you had to select a planet or a moon and do some research on that planet and then you had to design a rover to go to that planet and there are a lot of obstacles in that whole design portion, and Chris is going to be able to help us answer some of those questions today.

 

I know then after that, you have to design and build this rover that collects data about three different aspects on the planet or the moon if you chose that. So let's go straight to your questions and see what we've got here for you guys today and see how we can help you out.

 

The first question we have is from Miss Mead's science class from Iowa. Michelle asks: How can we stop radiation from damaging our rover on Mars?

Chris speaking on screen.

Chris: That's actually a very good question. Radiation's just one of the factors that your robots will have to deal with when they're outside of the Earth environment. Mars does have some atmosphere, it's pretty limited, so that will help prevent some of the radiation factors. The further you are away from the sun, the less you have to worry about direct radiation being an issue, but we will have to cover our rovers when they go to Mars. In fact, we already do this. The rovers that fly to the planets now have protective coverings, either in metal or typically in blankets or other things that lay on the top of them.

Picture of a rover prototype.

You see a little picture of a rover, prototype-type rover that could fly to Mars and you can see the surface coating on them is the white painted cover. The metal and the painting on top of them have some radiation reflection capabilities to help prevent ultraviolet - typically ultraviolet's the most dangerous one from causing damage.

Sherri speaking on screen.

Sherri: Okay, great. Well Joe from Milwaukee, Oregon 10th grade class wants to know when it comes to selecting the first manned Mars crews, is there going to be any above normal astronaut pre-requisite type requirements?

Back to Chris.

Chris: Yeah, I think you can safely assume that the first crew that gets to go to Mars will be very special people. Since it'll be multiple people going, we'll be looking for a diversity of skills. Some will be engineers in that group, there will almost assuredly be one or two doctors in the group in case somebody gets hurt, there'll probably be a scientist or two, trained primarily in geology or physiology, the types of fields that will tell us a lot about the Martian environment when they get there.

 

So I think you can assume that they'll need advanced training. They don't have to be super humans or anything unusual like that, just a good academic background in the kinds of fields that we'll need to study Mars.

Back to Sherri.

Sherri: Now, expanding on that, Chris, will any of those astronauts need to know how to work any rovers? Will they be taking rovers with them to collect samples and not only are they engineers, are they going to have to understand how those rovers work, be able to fix them, that sort of thing?

Chris speaking on screen.

Chris: Yes. It's very likely when we take humans to Mars or any of the other surfaces, we'll take along with us rovers or devices that can help them get their work done. The astronauts will not have to build those devices, they'll already built and packaged and sent. But already our astronauts are capable of fixing almost anything that goes with them into space.

Graphic of astronaut working on surface of the moon or Mars.

So we'll train them how to fix those rovers or to replace a wheel, for example, if that's what's necessary, and keep the devices running well while they're there.

But the rovers will be fairly intelligent and capable of devices in their own right so they'll be able to most likely they will do a lot of their own work without needing a lot of human direction directly. So the astronauts will work with them, but they won't have to drive them by hand or do all the work that keeps them running. The rovers should be able to do some of that.

Sherri and Chris shown on screen.

Sherri: Great. So that's very helpful for those of us planning our rovers going to other planets, that it does need to be self sufficient to some extent.

Sherri speaking on screen.

Well Philip, from Mrs. Debertins 4th and 5th grade class would like to know how you make a solar panel and how do you make your rover float.

Chris is speaking on screen.

Chris: Okay. Two very different questions. The solar panel, of course, is the way we get energy to most of the robots that we send into space today, and it's the most likely way future robots, at least in the inner part of the solar system, maybe out through Mars, will get their energy.

 

A solar panel is made of a very special material which is capable of taking the sunlight and converting that sunlight directly into energy. It's backed by the electronic circuitry which then puts that energy into batteries or wherever you need it.

Picture of a rover with solar panel on top.

You can see on the very top of the Sojourner model here that there's solar panels right over the very top, they capture the sunlight. This, while it isn't using real solar panels, it looks a lot like this.

 

There's a glass coating on top to protect the solar material, and then there's a special material that captures and converts the electricity. So that's how you make a solar panel.

Chris is speaking on screen.

Now making a robot float is a very different question. If you want it to float on some type of liquid surface, then you basically create a boat,

some kind of sealed bottom which keeps the liquid out and lets the electronics and circuitry work.

 

If you want to make it float in an atmosphere, let's say you want to go to Jupiter, Jupiter certainly has a very thick atmosphere. Now you're talking more like an airplane-type device and you will have to create lift with something like wings. So both of those are certainly possible. It'll depend very much on the planet or the moon you're trying to go to and what type of environment's there.

Sherri is speaking on screen.

Sherri: Okay. Doug's question from Miss K's class ties in nicely with the first part of this question we just talked about. Doug wants to know how long with a rover battery last?

Chris is speaking on screen.

Chris: It depends a lot, of course, on the type of battery that we're using. A battery that you use let's say in your CD player right now probably won't last more than a few hours and that's fine because you can just walk out to the store and buy a new battery.

Graphic of space vehicle on planet surface.

If we're on Mars or on a moon and Jupiter, there aren't very many battery stores around. So, we use a couple of different types of technologies that both help the batteries last a long time

Back to Chris.

as well as let the rover create it's own field while it's there.

 

So batteries typically will last many hours, sometimes as many as a couple of days before they run out of energy. And then they'll recharge using the solar panels. In a larger mission or a larger rover, you'll have extra batteries that are being charged while you're using one set of batteries, you're getting another set of batteries recharged while you're waiting.

 

We can also use a technology called fuel cells. Fuel cells combine hydrogen and oxygen together to create energy as you need it. Both the shuttle and the space station use fuel cells right now. They do have to be recharged with water eventually. Well that might be possible, depending on what planet you go to, you'll be able to generate your own hydrogen or water in that environment.

 

So fuel cells are certainly one technology, fuel cells can potentially last for weeks, maybe even years depending on how big the fuel cell is and whether you can recharge it. Batteries that we usually use in robots will last many, many hours, often days before they need to be recharged again.

Sherri and Chris shown on screen.

Sherri: For those of you just joining us, this is a Web cast about the Space Day Design Challenge #2 which is for those of you out there have selected a planet or a moon and have researched it and trying to design a rover to go to that planet or moon. And we have our robotics expert, Chris Culbert, with us here to help answer some of your questions if you have run into obstacles in your design challenge.

Sherri speaking on screen.

Let's take the next question. Tucker and Will want to know if lasers would be affected by the atmosphere on Mars if they used one on their rover.

Chris speaking on screen.

Chris: Lasers are certainly an optical device and any form of optical device is going to be affected by the atmosphere that it has to go through. But lasers work just fine in the Earth atmosphere which is much thicker and bigger, if you will, than the atmosphere on Mars is, so lasers are not going to be affected a whole lot.

 

Now the thing that might affect a laser, depending on what you're going to be doing with it, will be dust. And there's not a lot of atmosphere in terms of oxygen or even carbon dioxide which most of the Martian atmosphere is,

Graphic of astronauts in dust cloud on surface of a planet.

but sometimes storms can kick up a large amount of dust and leave it suspended above the surface for many hundreds of feet and that could affect the laser quite a bit. Maybe even making a laser not very useful. So if you want to use a laser on Mars, you need to be careful to plan how you're going to use that if a dust storm occurs.

Sherri speaking on screen.

Sherri: Okay. Well, we've got two questions here that kind of tie in with one another. Ronnie wants to know what kind of wheels for my rover do you recommend for going to Pluto which is very rocky. This ties into Mrs. Meade's science class from Iowa. Tracey's wanting to know if it's better for her rover to have wheels or a track.

Back to Chris.

Chris: Let's start with the wheels and the track question. You've probably already seen tracks, I call them tank treads like on tractors, those are very versatile way of providing good traction on a variety of surface conditions. So tank treads, or treads of some kind make a lot of sense when you don't really know much about the surface at all.

Graphic showing space vehicle on planet surface.

Now the problem with them and the reason you haven't seen any rovers use them to date is they tend to be very heavy, they're harder to maintain,

Back to Chris.

and if they get gummed up with dust and dirt and so on, they tend not to work very well. Wheels can be self contained, they're easy to close up so the dust can't get into them and affect them. Bigger wheels can work in a variety of surface conditions. We worked them very well on both Mars and the moon so far. Wheels, though, particularly on the nature of the material used to do them, we don't typically use rubber, we use metal wheels when we go to planets, they can be badly affected by the temperature.

 

So if you're going to go to Pluto, one of the things you're pretty certain about on Pluto, is it's going to be very, very cold. We don't know a whole lot about the conditions, it's very rocky, those rocks are made of ice or granite or stones of some kind, nobody really knows right now. Tracks might make a lot of sense on Pluto, a little less sensitive to the temperature conditions, they're probably isn't going to be as much dust, but again, they're very heavy and Pluto's a long way away. So that would be a tough decision, you'd have to make some trades based on the size of your probe and your rover and how far you're going to send it and how much it's going to cost you to get it there and whether or not you can afford the tracks once you got there.

Sherri and Chris shown on screen.

Sherri: Speaking of Pluto being a long ways away, I know if we were to travel on the space shuttle, fly straight to Pluto today, traveling at 17,500 miles per hour would take us 15 years just to get there, so obviously weight is going to be a consideration for us to get a rover with that kind of weight issue that far out in the solar system.

Sherri speaking on screen.

Well, Miss Mead's class from Iowa, this is Sasha, and she wants to know how they can protect their rover from the temperatures caused by the volcanoes on Io.

Back to Chris.

Chris: That's a very interesting question. It depends a lot on what you want your rover to do. The volcanoes on Io are pretty active, we've already seen them exploding just from the probes we've sent back, so it's logical to assume that they erupt fairly regularly. They create a molten material which means the temperatures are very high, so the first thing you have to decide is do you want your rover just to climb around the mountain and not actually get into what correlates to a lava field on that volcano, do you want it to actually go down inside them. That'll change quite a bit the type of temperatures you have to deal with, and the types of materials that create the temperature.

 

A lava is, in essence, a liquid, a molten rock of some kind so not only do you have to deal with temperature, you have to deal with some liquid affects of that lava getting into your rover. So there are some things you'd certainly have to do, some kind of plating or protective covering on all the critical elements for the rover would certainly be necessary. And that plating would have to protect both from the physical aspects of running into the - maybe the lava, as well as the temperature conditions and that would be an insulation of some kind inside your plating.

 

Then you have to figure out how your mobility mechanisms, wheels or treads or whatever, how is that going to drive on top of whatever it is you're going around that's creating the heat. And you don't want your wheels to bring all that heat into your vehicle, so you need some kind of system to insulate the wheels from the rest of the body of the vehicle. Very good question. It can be very difficult.

Sherri speaking on screen.

Sherri: Jackson's 6th grade class, Chris, would like to know what are the degrees of freedom and why are they important when they are designing the rover.

Chris is speaking on screen.

Chris: We often describe robots in terms of degrees of freedom. A degree of freedom is essentially, on a robot at least, it's a joint.

Chris demonstrates degrees of freedom with his right arm and shoulder.

Let me hold up my arm here and you can see this. My elbow has one degree of freedom. It can move the arm this way. I can't really move my arm like this from the elbow, I can do that with my shoulder, but my elbow doesn't go that way. So there's one degree of freedom in my wrist, I'm sorry, in my elbow. My shoulder here provides three more degrees of freedom. It can lift it up, it can move it backwards and forwards, it can rotate around.

 

So each direction or each movement motion, each angle you can move it through, is one degree of freedom. The rover arms that we use today on the shuttle, and the space station, the shuttle has six degrees of freedom, the station has seven degrees of freedom. So the degrees of freedom are very important for a robot to tell you where it can reach to.

Chris demonsrates one degree of freedom with his right arm.

One degree of freedom can only move in one way, and if I want to get to something that's over here, and I can only move like this, I can't get there.

 

It requires a minimum of six degrees of freedom to be able to move an arm just about anywhere you want it to in the workspace. So the more degrees of freedom you have in a robot, excuse me, the more things you can do with that robot, the more complexity, the more complex tests it can perform.

 

The robots we're designing for the long term future, something like Robonaut, Robonaut now has 43 degrees of freedom in it, and there's a picture of Robonaut for you.

Video of Robonaut moving and shaking hands with an astronaut.

You can see it's got hands, it's got a neck, it's got a waist, it's got arms, the ability to handle tools and manipulate them very wide range of objects, comes from having lots and lots of degrees of freedom. So the range of freedom is a very important measure of how much a robot can do.

Sherri and Chris on screen.

Sherri: That was fascinating. Thank you, Chris. Casey is from Maryland and she's in the 4th grade and she would like to know - they're struggling with what kind of material they can make their rover out of for the extreme cold on Pluto.

Chris speaking on screen.

Chris: Okay. You're probably going to use a variety of materials. Just like when you go outside when it's very cold outside, you probably put on many layers of clothing. A shirt, and maybe a sweater, and then maybe a coat, maybe something on top of your coat. The more layers you have, the better protection you get from the cold. Robots are likely to be designed in a very similar manner.

 

They'll have a very strong outer coating, probably made of some kind of metal content, but the metal has to be light and very strong. For space vehicles, we've often used metals like titanium or other very strong but light metals that are expensive, difficult to find, but they're very good for space vehicles. That would probably just be a first layer. Inside of that, you'd probably have other layers. Some of those layers would have potentially some form of insulation, probably not the same insulation you'd use in your house, but something a little more designed to use in space to deal with more extreme colds.

 

And you also have to deal with the heat as well. If you're directly in the sun, particularly in the inner part of the solar system, you've got to be able to get rid of a lot of heat. So we haven't done many robots like this, but our human sometimes have water-cooled suits that they wear. And we have seen robot designs that include water cooling, just like your car has a radiator, and pumps water through the engine to cool it down, you could use some kind of liquid or even a gas as a way of actively cooling down your robot or heating it up, either way works. So, you use multiple systems, it's a very important part of designing anything that goes into space, dealing with the temperatures, both hot and cold, and creating a robot which gets the temperature and environment it needs to operate in.

Sherri speaking on screen.

Sherri: Tequila, who's a third grader I presume, has chosen the Moon to build the rover for, and Tequila's wanting to know if the moon, our moon, Earth Moon, is cold. We've been talking about other planets, some being extreme cold, some being extreme warm.

Back to Chris.

Chris: The moon is like most of the other moons in the solar system, it does not have an atmosphere. Our atmosphere is what keeps our temperatures fairly moderate. They don't go really, really cold, they don't go really very hot, some people think Houston's really, really hot, it's not that bad. But if you go onto the moon, there's no atmosphere.

A picture of the moon with a space vehicle orbiting it.

So if you're in the sunlight, it gets extremely hot, hundreds of degrees potentially, and when you're in the shadows, behind a mountain or in a place where the moon, the sun doesn't reach, it can get extremely cold. A few hundred degrees below zero is not unusual on the moon.

Back to Chris.

We've seen places that get 150 to 200 degrees below zero. So the moon can get very, very cold. It depends on where you are

Back to Sherri.

Sherri: We've got another question from Miss Mead's science class wanting to know if radiation would affect the spectrometer on their rover.

Chris speaking on screen.

Chris: Yes, radiation could. The spectrometer is a device that does rely upon - it's a way of measuring information about the materials you're going to do. It doesn't directly interact with radiation, but it's certainly possible that certain types of radiation would affect the elements that - of the components that make up the spectrometer and could even interfere with its readings, depending on the environment. So I guess it could that wouldn't be a major concern to me.

Back to Sherri.

Sherri: Fayth, Grade 1, Miss Nedd's class wants to know that when a person is visiting the moon or any other planet for that matter, do they send out robots before they actually go there? And what are the dangers to those robots, if any.

 

Chris: Yes, we often send some kind of robotic device. In fact, everywhere we've sent humans in space, we've sent robots first. It's very important to use the robots to help us learn more about the environment. Any time you go someplace we've never put a human before, we want very much for our humans to be safe and to be able to return back to Earth and tell us what they've seen.

Picture of rover orbiting moon.

So we send the robots first to tell us something about the environment, they have instruments that can teach us things about what we're going to find, what the surface conditions are like, what the temperatures are like. We know some of that already, but a robot can provide us with very detailed information, right then and there. So it's very important for us to help understand what our humans are going to deal with when they decide to get out of their space vehicle.

Back to Chris.

And there are a whole lot of dangers both to the humans and the robot. The surface conditions can be things we don't expect, there's a lot of concern before we sent robots to the moon that the moon surface would not hold the weight of a human. But our robots proved that we could drawl around or walk around on the moon without sinking into the dust of the moon.

 

And that was certainly very important to our astronauts. They wanted to know before they went there. They can also tell us things about both the temperatures and the type of materials we're going to find. We would not want a certain kind of dust to clog up the air system on an astronaut's backpack. For that matter, we don't really want it to clog up the wheels on the robot. So we need to learn a lot of things about these environments before we can reliably and safely send people to them.

Sherri speaking on screen.

Sherri: Andrew from Mrs. Kuzyk 5th grade class in Bethel Maine would like to know if you could make solar panels hide under protection would it be better than if they were always exposed.

Chris speaking on screen.

Chris: Yes. Actually, we already do that. They have to have a clear coating on top of them so that the sun can reach the material which converts sunlight into electricity. But already, any solar panels you work with today have some type of clear protective coating built on top of them. Glass is quite common because it doesn't affect the light very much and it can be relatively strong.

 

There's other forms of materials that can be used to cover the solar panels to protect them without blocking the sunlight. So it certainly is important to protect them.

Picture of solar panels.

And there's some good pictures of some solar panels. You can't really tell what's on top of that, it's probably some kind of a clear plastic covering that's very light and reasonably strong.

 

Sherri: Chris, Brian writes in and wants to know if it's better to land their rover on ice or an unknown surface.

Back to Chris.

Chris: It's almost always better to land on a known surface. You don't know much about the environment, it could be slippery, it could be very loose and you might sink in some. If you know the ice conditions, that would generally be something you'd choose. If it's a very strong ice and you could land your rover on it without any risk of the ice cracking or breaking through. We don't know a lot of places in the solar system that have liquid environments. Europa, we believe is one. That's a moon of Jupiter and it looks like it has liquid underneath the ice coating.

 

So we're not quite sure how thick that ice is, but we have reason to believe it's fairly thick. We can tell from some of the pictures we've taken of craters and grooves on the ice. It looks like it's pretty thick. But in general, you would want to pick a known surface over one that you don't know anything about. But our pictures of the moons and the planets have told us quite a bit about the surface conditions. And for example today, we do not feel bad about landing on the surface of Mars, obviously or the moon. We've done that many, many times. There's a lot of rocks there, but we're pretty comfortable with the environment - we're not going to sink deep into it and not be able to get out and that there's nothing dangerous in the dust itself.

Sherri is speaking on screen.

Sherri: Another question from Miss Mead's science class. You guys clearly have done your homework, we are so glad you're joining us here today. Christen from the class would like a little more detail about the kinds of metals that could be used on their rover to protect them from heat and radiation. For instance, they know aluminum is lightweight, but would it be heat resistant enough?

Back to Chris.

Chris: Okay, that's something you'll be able to do a fair amount of research on. There's a variety of metals and there's no easy answer to that. Every time you're building a vehicle, you're making what we call trades. You're going to have to make a balance between how much weight it is compared to how strong it is, compared to how well it can handle heat or cold.

 

So you have to compare the thermal properties of the material with the strength properties of the material with the weight characteristics. All three of those would have to be analyzed to determine what makes the most sense. Aluminum is certainly used quite extensively, both for its strength and for its weight. It's very strong to its weight compared to something like steel, for example. Steel's stronger than aluminum but it's heavier.

 

But you have to look at the thermal characteristics. Steel tends to reject heat a little better than aluminum does. So you have to do some comparisons. There's actually quite a bit of material you often find about the thermal characteristics of provided materials and then balance those thermal conditions with the weight and the strength characteristics that you believe you need.

Back to Sherri.

Sherri: We've got Jeanine who is a 4th grader in Maryland and she says their sending their rover to Pluto and wants to know if we have any suggestions on how to dig a hole in that surface. For instance, would they have to have their rover have a diamond cutting blade?

Back to Chris.

Chris: That's an interesting question. We don't know a whole lot about the surface materials on Pluto. It's the only planet in the solar system we've never even gotten very good pictures of. If I were designing a rover to go to a planet like that where I had very, very little data about the conditions, I'd probably send a variety of cutting instruments. The drill is the most common we use initially. So some probably drill and I would probably make it a very, very hard drill bit so that it could deal with almost anything it found. We know it's going to be cold and very, very cold very hard rocks might be something you'd deal with. So yeah, a diamond tipped drill bit or cutting blade would probably make pretty good sense.

 

You might actually send two different types, one with diamond and one with other types of conditions so you could get information about the strength and the hardness of the surface and that would tell you something useful about future missions.

Sherri and Chris shown on screen.

Sherri: Looks like Lance is choosing to land his rover on Mars, but he's not sure where. He's wanting to know whether the south pole or the north pole would be more dangerous.

 

Chris: Don't think we have very good data on which one might be more dangerous.

Picture of Mars.

We know the poles are very interesting because of the potential for water. And you can see a little bit of an icecap on both poles. I believe the south pole tends to have a little more ice than the northern pole, so it might be more interesting for that reason. Water, of course is very important if you can find it because you'd be able to mine the water and turn it into useful materials, either as something - water that humans could drink or use, or as a fluid that you can separate to create an energy.

 

Hydrogen and water are what go into hydrogen and oxygen to make water and you if you can convert that to raw oxygen, you can generate electricity from that. I don't think we have much data about which one might be more dangerous, though.

Sherri speaking on screen.

Sherri: Kathy from Mrs. Kay's class in Bethel, Maine wants to know if there's any way you could store water in a rover and what would you need water for a rover - in your rover for, anyway?

Chris speaking on screen.

Chris: Okay. It depends a little bit on what you want your rover to do and whether or not there's humans there. Anywhere we send humans, water's very, very important. We all need water just to live. So if we're going to send rovers along with humans exploring the surface of the planet, then yeah, it would make a fair amount of sense potentially to have that rover capable of storing the water that humans would use. And sure, it would be very easy to put water into a rover, we carry water around with us all the time in bottles or plastic bags or metal tank containers. So you'd build a tank into your rover somewhere to store the water.

Picture of astronaut and rover on surface of planet.

Now you'd want that tank pretty well protected, and you'd probably heat it so that when it was cold your water wouldn't all ice up.

Back to Chris.

And you may also have to refrigerate a little bit so that your water didn't get too hot if you were out in the sun for a long span of time. There's lots of way to store water in the rover. And there's some reasons to use it if there's humans there. If there wasn't a human around, and there's not many reasons unless you're going to use it as a fuel source of some kind.

Back to Sherri.

Sherri: Jeanine is a 4th grader in Maryland she would like to know how large are most rovers in general.

 

Chris: We certainly use a very wide variety of sizes. We have sent rovers to almost all the planets - most of them didn't actually land on the surface, though. We particularly call those satellites more than rovers, but you'll sometimes see those referred to as rovers. And those can get very large if they're not going to land on the surface. Our rovers that have landed on the surface tend to be much smaller. The sojourner was very small, no more than about a foot and a half long.

Picture of Sojourner in background of picture on planet surface.

The next generation of rovers that will go to Mars will probably be oh, about five to six feet in one direction and maybe two to three feet tall depending on what they need to do. There's a picture of sojourn on the background of that one. The front part there is actually the lander vehicle. The rover itself, we have to protect it before it gets the surface so that causes a lot of the complexity, we have to worry about weight all the time. So the smaller the rover is, the easier it is to get there because there's less weight. There's a good picture of sojourn and it's very small, as you can see.

 

Those wheels are only about two three inches across. It's a very tiny rover. The next generation of rovers will get about three times that size. Now, in the long run we have humans on the surface as well, they'll have to get much bigger, closer to the size of a car. Because we'll probably going to want the humans to be able to ride on those rovers and drive them around.

Back to Sherri.

Sherri: Well speaking of size, Doug wants to know what the biggest rover is that NASA has ever built. And there's one for you put your thinking cap on for.

Back to Chris.

Chris: Well, that's actually pretty easy. That would have to be the lunar vehicle that we went with the astronauts to the moon. We Jurls them around on the surface, they look kind of like a dune buggy, you've probably seen pictures of them and they were big enough for two humans to sit in them. They sat on seats and they actually Jurls around the surface of the moon. That's certainly the largest rover we sent with people.

 

The largest one we've sent on its own, the largest one we sent that could crawl again went to the moon. We sent a variety of probes, both the Americans and the Russians sent probes to the moon all through the 60s and the 70s. I believe the Russians have sent some even more recently. And those got to be about the size of let's say a - oh, I don't know - certainly not as big as a car, maybe about the size of a go-cart or bicycle, if you will.

 

So those are about the biggest we've sent so far. We have sent larger vehicles that have even landed on the surface, but they couldn't drive around or move on their own once they got there. They landed and stayed put.

Sherri speaking on screen.

Sherri: Okay. Alexander and Tim who are in 6th and 8th grades respectively from Mrs. Fuller's class want to know - well, they've read that we hope to use Phobos for space station in the future and this caused them to become very interested in the project.

Sherri and Chris shown on screen.

 

They want to know what the temperature on Fobos is and does it very greatly?

Chris speaking on screen.

Chris: Fobos is a moon of Mars. It is very interesting both because of its location and because it's relatively good size for staging if you want to do things on the surface of Mars. But just like the moon of Earth, there's no atmosphere on Fobos so the temperatures will vary very greatly depending on whether or not you're in the sunlight.

 

Now Mars is considerably further away from the sun than the Earth is. So in general, Fobos is going to be even colder than the moon is, and not quite as warm even when you're in the sun. It's because there's less energy the further away you get from the sun. So Fobos is a good place to stage missions onto the surface of Mars. So yeah, it is possible we'll build some kind of a base there in the future.

Sherri speaking on screen.

Sherri: Okay for those of you just joining us, we want to remind you that this is a Web cast in conjunction with Space Day and you can visit the Web site at www.spaceday and read all about the design challenges. This one is about selecting a planet and then trying to design a rover to go to that planet and conduct activities. And we are here at Johnson Space Center where our robotics expert, Chris Culbert,

Sherri and Chris shown on screen.

is answering some of your questions about the obstacles that you may be facing in designing your rover. Let's take your next question.

Sherri speaking on screen.

Mrs. Mead's science glass again would like to know if there's a way for rovers to repair themselves if something breaks and that comes from Nick.

Chris speaking on screen.

Chris: Yes, there are ways and in fact it's a very important type of technology. Because the rovers are going to be a long way away from help, particularly if there's no humans there yet, it is important for our rovers to be capable, or any form of robotic device, to be capable of some simple repairs at least. If your wheel falls off, it may not be able to handle that. But just like you can put materials inside your —

Picture of rover and astronaut on surface of planet.

and there's some interesting wheels, right there.

 

Just like you can put materials inside your tires so that if you get a puncture it seals the puncture and keeps it inflated enough to keep going, there are ways we'll be able to build rovers that are capable of handling certain kinds of failures themselves. A lot of electronics and the computers will probably be very redundant, so we'll build two systems to do one job. So if one of those systems fails, we have another one available right away to take over. Redundancy is something we try to build into rovers but it depends on the nature of the failure and the type of problems they'll have to handle.

Sherri speaking on screen.

Sherri: Dexter from Miss Mead's science glass from Iowa would like to know what kinds of tools could test rocks and soil on Mars.

Back to Chris.

Chris: There's actually a lot of different kinds of tests we'd like to perform. We mentioned the spectrometer earlier which tells you a lot about the type of material that's in the rocks. We'd also like to know beyond the material, we'd like to know about the size and the weight, so just something as simple as a scale could be a very important piece of data. If we'd like to know the density of that material, we can measure specific gravity by putting it into some kind of a liquid and looking at the amount of liquid displaced.

Those are all very simple experiments that you can do in your own classrooms. There's also more sophisticated tools that could be built in very, very sophisticated scientific instruments which are capable of taking a sample of the rock and then getting all the way down to the atomic level trying to figure out what all the elements in it are. Pictures and just reflective light can tell you things about what the material and what the conditions it was created under, so there's actually a lot of different types of tools we can use.

 

You can probably get some good research on the type of instruments that have been sent on probes to both Mars and the moon already. So that's one area you could learn more about the tools that would be available out there.

Sherri speaking on screen.

Sherri: Okay, well Jeanine is a 4th grader in Maryland and she wants to know - they don't think that their solar panels are going to work on Pluto, so they're looking for alternative ways to make their rover move. I know we talked about fuel cells earlier.

Sherri and Chris shown together on screen.

Chris speaking on screen.

Chris: Yeah, that's actually an area that's getting a fair amount of attention these days. The further you go away from the sun, the less useful solar power is as an energy source. So that means your rover is going to have to take an energy source with it unless you get lucky and find something in the environment it goes to. A place like Pluto, we don't know enough about right now to be able to assume there's energy we can use there. So the most common options, some form of a fuel cell something we're familiar with, we use quite a bit, there's a lot of good technology there.

 

There's limits on their life, though. If you want a large system or a lot of energy, and you want it to live for a long time, you'd probably have to look at something like nuclear power. Nuclear power though it hasn't used in space a whole lot so there's a lot of development that has go be gone through and we have to make sure everybody was comfortable that it was safe before we can send it into space.

Sherri speaking on screen.

Sherri: We have about 20 minutes left in our Web cast. We're going to go ten minutes after since we got ten minutes late, so we want to encourage you guys to keep submitting your question. Those of you out there that are shy, don't be shy, we receive your questions right into our chat room, that's what we're here for, to help answer your questions on your design project. Again, reference the www.spaceday.com Web site and that will link you to all sorts of resources that you'll need for your project design. I know many of you, based on your questions, have already done a lot of research and we are very proud of you for that, very excited to see the final product.

 

Let's take another question. Will wants to know, I know we've been talking about the poles on Mars, if one or the other is more bumpy and/or uneven. Do we know that yet?

Chris is speaking on screen.

Chris: I don't think we have a lot of data to tell us the answer right now. We've got pretty good pictures of the equator region of Mars. And we have some data about the poles. Most of our satellites have taken pictures that go around the planet this way rather than this way.

Picture of satellite orbiting Mars and taking pictures of the surface.

So I don't think we have a lot of data about just how bumpy or uneven —

Chris speaking on screen.

I think it's fair to assume they're both fairly - compared to your driveway, they're very bumpy and very uneven. But whether one's more than the other, I don't think we know much about that yet.

 

Sherri: We'll we've gotten a lot of questions from Miss Mead's science class in Iowa. And they have their ePals group already set up and they want to share with everyone what their email address is for all of you other schools out there participating in this design challenge. If you wish to email them and talk amongst one another about your challenges, their ePals address is North Winnichec, there are about 49 kids there working on this project. So please know that this school has an ePals group from the spaceday Web site that you can contact them and talk with them about your projects.

 

Sherri speaking on screen.

David is from Miss Nedd's class and he gets a little bit off the topic of rovers, but still talking about exploring space and humans exploring space and needing rovers, but he wants to know why can't astronauts visit the moon without protective clothing.

And obviously some of these elements play right into why certain things need to be in place for rovers.

Sherri and Chris shown on screen.

Chris: Well, we've already talked about how the moon can get very hot and very cold.

Chris speaking on screen.

So one of the reasons for the protective clothing is to control the temperature that those astronauts' bodies feel. Just like you wear more clothes when it gets cold outside, and maybe a little less when it gets warm outside, we want to make sure our astronaut's stay at a very comfortable temperature when they're outside.

Picture of astronaut walking on the moon.

But the most important reason is because the moon does not have any atmosphere. It's a vacuum. And so inside that spacesuit is where the astronaut gets his oxygen from, his air, so he can breathe.

Back to Chris.

And pretty much everywhere we go in the solar system our astronaut's have to take air with them. So they'll always need a protective suit, if nothing else just for the air. And the heat and the cold are very important, too. They don't like getting real hot.

Back to Sherri.

Sherri: Looks like the 4th grade class in Frederick, Maryland has chosen Pluto as their planet and they want to know how long it would take to get information about the soil or air back from Pluto to the Earth.

Back to Chris.

Chris: This is something you'll be able to look up on the Internet and probably should do a little research into, but let me give you some basic guidelines. The further away you are from the Earth, the longer it takes to get information to get there. That's because we send information right now using radios, basically. And radio waves move at the speed of light, so the further you are away from the Earth, the longer it takes us to get there.

Pluto has a very unusual orbit that takes it inside the orbit of Neptune for a short period, and then much further out. So how long it takes will depend to some extent on where Pluto is when you land there. And then it's going to take quite awhile, I'll let you look up just how long.

Sherri and Chris on screen.

Sherri: Thanks, Chris. Mrs. Fuller's class, 6th and 8th graders have another question. They want to know how images get back to Earth from your rover assuming it has a camera.

Chris speaking on screen.

Chris: Okay. Yes, pretty much all the rovers, at least all the satellites and probes we've sent to the planets, today have cameras. Cameras are very important. They tell us quite a bit about the environment. But to put one - let's say you have a rover that lands on the surface of Mars and crawls around like Sojourner did. You actually have to provide quite a bit of data. Sojourner itself did not have a camera on it.

Picture of Sojourner and lander vehicle.

This picture was taken by the lander vehicle, Sojourner stayed pretty close to the lander vehicle and it was able to take a picture from the lander vehicle.

 

Now larger rovers in the future will probably have cameras on them themselves. So, the way it has to work, the rover will have to have both a camera and a radio system. You capture the camera image, you store it as a digital piece of information on your computer on the rover, and then you send that information through the radio system back to your lander craft most likely,

Picture of a rover with camera and radio system.

something like that one right there, and the lander craft will broadcast that either all the way to Earth or to a satellite that's in orbit around the planet.

 

And so it's actually a pretty complicated system. You're using radio systems and you're sending digital information just like we sent digital information over the Internet right now,

Chris speaking on screen.

but you have to have all those various components in place to be able to get the information from the rover all the way back to the people on Earth. And I forgot one of the most important elements, when it gets to Earth, we have to have big, gigantic radar dishes - they look like radar dishes, they're actually radio dishes, to capture that information and it's processed through computers again on our side before we actually know what that picture looks like.

Sherri speaking on screen.

Sherri: Divante wants to know most of the moon has holes, but why are those holes there and how can they work around those holes with their rover.

Back to Chris.

Chris: Okay. The moon, like most of the items in the solar system, well, let's say it this way.

Picture of moon.

The solar system's got a lot of material in there. Everybody's familiar with the planets. You've probably also heard about comets, or asteroids, these are much smaller objects that float around in the solar system. There's actually millions and millions of those small objects flying all around the solar system and every once in a while, they run into each other.

 

Sometimes they make a pretty big hit when they hit something. On Earth, we're pretty well protected again by our atmosphere, and most of the asteroids or comets that hit Earth, we call meteorites by the time they get to the surface, they get burned up by our atmosphere. The moon, of course, doesn't have an atmosphere. For all those objects over the millions and billions of years the solar system's been here keep hitting on that surface of the moon, and that's what's created all the holes. There's some very, very big holes in the surface of the moon because some pretty objects have run into it over time.

Picture of satellite orbiting the moon. Planet Earth is in the background.

Our rovers will have to be able to either climb in and out of them, the smaller ones, or drive around the bigger ones. So this will affect both whether or not your rover —

Back to Chris.

how steep a surface your rover has to climb over and whether it has to be able to climb over not just rocks but over a cliff, if you will, on the edge of a hole or how much range it has to have if you're going to drive around the bigger ones.

 

There's some very large craters on the surface of the moon which are tens of miles across, so to go all the way around it would take quite a bit of range. This is an important factor to consider when you're designing your rover.

 

Sherri is speaking on screen.

Sherri: Okay. Tucker is a 5th grade student and Tucker, your question is how deep is the average canyon. Now we don't know what planet or moon you have chosen, so we're not really sure how to answer that in terms of how deep and average canyon is, so we'll lump the entire solar system together might be a little challenging for us, so if you want to be more specific and write your question in, we'll be happy to answer that.

 

Well Doug wants to know if he can use his solar power on Mars, and I don't know if we've addressed Mars specifically, I know we've talked about Pluto, Chris. If we have, please forgive me, I can't recall all the planets.

Sherri and Chris shown on screen.

Chris: Solar power will work well on Mars, the Sjourner had solar panels on top of it.

Chris speaking on screen.

Mars is still in the inner solar system, so solar energy is a fairly viable source of electricity on Mars. Now, the limitation might be solar power can only generate a few watts of energy, maybe in the long run a few hundred watts. If you want to do anything really big, if you want to dig a really deep hole, for example, you probably need more energy than solar power can get to you. You'll have to store up a lot of solar power in the form of batteries. The solar power will work just fine on the surface of Mars.

 

Back to Sherri.

Sherri: Well, along that same line, Chris, Daniel and David are wondering about their solar power usage on Jupiter and its moons.

Back to Chris.

Chris: The surface of Jupiter, which we really don't know very much about because we can't get to very easily, probably is not going to work for solar power. There's a very, very thick, very deep atmosphere around the planet of Jupiter, and I don't think you'll be able to use solar power because you probably won't be able to see the sun. Solar power has to be able to get energy that's beamed from the sun to be effective. So I think you should probably assume if you want to go to all the way to the surface of Jupiter, you probably can't get solar power.

 

There are some scientists who believe we'll be able to use solar power in the upper atmosphere of Jupiter and capture enough energy to be able to fly let's say a balloon or some kind of a glider in the upper atmosphere. The moons of Jupiter for the most part don't have much of an atmosphere, so that they do get solar energy, but you have to remember you're not just circling around the sun, then, you're also circling around Jupiter.

 

There may be very long periods of time where Jupiter blocks your rover from getting any solar light. So, solar power will probably work on the moons, but you'll have to be careful how you use it because you have extended periods where you won't have access to it.

Sherri speaking on screen.

Sherri: Wyatt and Christian's group from Miss Mead's science class in Iowa have a question about costs. Apparently, they're looking at the cost involved with their rover and they're wanting to know what's the typical cost per pound. It looks like they're trying to go to one of the Jupiter moons. Now I don't know if we've determined that already or not, but could you talk a little bit about that?

Chris speaking on screen.

Chris: Let's see, there's not - well, let me put it this way. It will depend an awful lot on the type of launch vehicle you use. The primary cost of getting a pound of payload into orbit is associated with the vehicle that you use.

Video showing space shuttle launching with rocket boosters.

Right now, those costs range anywhere from many thousands of dollars to tens of thousands of dollars per pound. It can be very expensive even to orbit right now, obviously. NASA is working on technologies where we hope to lower the cost of getting a pound of payload into orbit to, let's say, as little as a thousand dollars per pound.

 

But we don't have that technology today. We're still working on that for the future. Right now, if you want to send up anything on the space shuttle, it costs many, many tens of thousands of dollars.

Sherri speaking on screen.

Sherri: Andrew from Miss Kay's 5th grade class in Bethel, Maryland has a further question about tires versus treads, wanting to know if - which one would be better on Mars and which type, like skidder tires?

Back to Chris.

Chris: We've used wheels quite successfully on Mars to date. We've not used treads, mostly because of the complexity and the weight of the treads, but I think tracks would work quite well on many parts of Mars. But, remember tracks generally aren't as good going over rocks as some kinds of wheels are. And if you see pictures of the Mar's surface,

Picture of rocks on surface of Mars.

you've seen it's got a lot of rocks on it. There's a pretty good picture. Some of them are quite big.

 

Treads could cover the smaller rocks if the vehicle's big enough. So it's a trade.

Back to Chris.

It depends on what function you want your vehicle, or your rover to perform, how far you want it go and how much energy you have to drive it there. Skidder tires, I'm not quite sure what you mean by Skidder tires, we use something called skid steering very frequently on rovers, which is a way of having all four wheels drive - it's kind of like a four wheel drive, if you will. But all four wheels not only can drive at the same on a four wheel drive, but they can also all steer at the same time. And that's called skid steering, skid direction,

Picture of rover bumping against large rock on surface of Mars.

so that's what you might have in mind and that does work quite well on a surface like Mars.

Back to Sherri.

Sherri and Chris shown on screen.

Sherri: Well Chris, can you think of any general tips that you would give the students out there, these 4th through 8th grade students who are designing their rovers from your knowledge base that we maybe haven't talked about yet?

Chris speaking on screen.

Chris: Probably the most important thing I can suggest you do is decide what it is you want your rover to do first before you think about how you're going to design your rover, or what it looks like, or what kinds of wheels it has or what kind of instruments it needs, you have to start with understanding your requirements. And the requirements come from the mission you want the rover to perform. So the very first thing you should do is define the mission for the rover.

 

Am I going to go pick up rocks, am I going to go travel 100 miles and measure the changes in the surface temperature, what it is your rover does is the most important thing you can figure out first. From that, you can build a design which is well created to meet the needs of the mission you want to perform. Beyond all that, remember very much weight is very, very important. The smaller and lighter the rover is, the easier it's going to be to get it to where you want it to go to.

Sherri and Chris shown on screen.

Sherri: We've got about six minutes left and we want to encourage you to take this last opportunity to submit your questions into the chat room. Shane from Miss Clark's 6th grade class in Pennsylvania would like to know - he says that scientists believe that Titan's surface is tar-like and if their rover lands on this surface, first of all could it and second of all, how can they move through this kind of substance?

Back to Chris.

Chris: That will be very interesting. I don't think - yes, I've actually seen some of the scientists' reports which suggests there might be a tar-like surface on Titan, maybe some methane material or something along those lines. If it truly is tar-like, it would very sticky, very thick, very gooey, and that would be difficult to drive a rover through. That would be a tough one. You could probably land the rover there, getting it to drive around in those kinds of materials might be tough. The tread, for example probably wouldn't work with tracks because they'd get all gummed up.

 

So you'd probably want some kind of wheeled vehicle, maybe using very thin wheels and a lot of them so that it wouldn't get stuck in the goo as much, that might be an idea.

Sherri speakin on screen.

Sherri: Jeremy from Placerville, California was wondering if a car battery would last long enough to do a few tests on the moon, Europa, and if the battery wouldn't last, how would you make or buy a solar panel. I know we talked about that a little bit earlier.

Sherri and Chris on screen.

Chris speaking on screen.

Chris: A car battery's actually a fairly decent amount of energy, regular sized 12 volt battery. It would last long enough to do some tests certainly. I'm not sure it could survive being put into orbit. Remember we have to get all the stuff into orbit, and the only way to do that is to lift them off on a rocket which shakes your vehicle up a lot, and you have to go through three or four G's if it's a manned or even more if it's an unmanned.

 

So I don't think I'd send a car battery into orbit right now. But if you could get into orbit, I think it would probably work reasonably well on Europa for awhile. It would not last real long, in my opinion. So, yes, solar panels might be necessary. Solar panels are something you can actually buy. You can walk down to Radio Shack right now and go buy a little bit of solar panel, you can do your own experiments in your classroom if you'd like to with solar panels. And you can actually buy those right off the shelf.

NASA doesn't go to Radio Shack and buy them. We go to special companies who make special ones for us to fly into space. But that's a pretty well understood technology and you can just buy it from a company these days.

Sherri speaking on screen.

Sherri: Okay. Brian from Mrs. Kay's class would like to know if they should use a laser to mine on Mars instead of a drill bit.

Back to Chris.

Chris: Okay, lasers and drills do very different things. And in fact, I would choose a drill and I'll you why in just a second. Let's talk about how they work first. A laser could drill a hole in the surface of Mars or anywhere by - what a laser does basically is it destroys the material by heating it up and blowing it out of the way. And that would create a good hole for you potentially, but it takes an awful lot of energy to do that. So that would be one problem with laser, it takes a lot of energy and it's hard to get energy all the way there.

 

The other thing is when we're digging holes on Mars or moon or wherever, we care a lot about the material we've dug up, so typically our drills are designed so they not just pull the material out, but they pull it out in a way that we can keep what we call a core sample. And we take that core sample back and analyze it. So I would choose a drill that doesn't take anywhere near as much energy and allows me to keep the material I've dug up, and that let's me do something with what I - the material that was in the hole when I drilled the hole.

Sherri speaking on screen.

Sherri: We're going to take two more questions. Miss Mead's science class from Iowa, Tiffany, wants to know how big could a rover be if it was only running off solar power on Mars.

Chris speaking on screen.

Chris: The size of the rover depends a lot on the amount of solar energy you capture and the batteries you've built into the system. The biggest we've sent so far that could actually move was Sojourner, which we've discussed was pretty small. We pretty well know and our next round of lasers that go to Mars later in this decade will be much bigger. I think they're called the Athena class. And they'll be up to, I think, five feet in one dimension. So that's pretty good size for the - and those will still be solar power driven.

 

You could probably build somewhat larger than that and still be solar power driven. How much larger depends a lot on the mission you want to perform and how long you need it to stay out there to do it.

Back to Sherri.

Sherri: Okay, last question. Chris, we appreciate it. Daniel and David want to know, apparently they're going to land on an icy surface. And if they wanted to test their icy surface, what kinds of instruments would they use and what kind of things should they test for?

Back to Chris.

Chris: Probably the first thing you'd want to know is here on Earth, most ice is made out of water. H2o, but not all ice. You've probably all seen dry ice. You've heard about dry ice - dry ice is not water, it's frozen carbon dioxide. One of the very first things you want to know about the icy surface is what is the ice made of? It is a water, is it carbon dioxide, frozen carbon dioxide like dry ice, is it a methane, what is the content of the ice itself? It may actually be a mixture of a variety of elements. So one of the most important things you'd want to learn is what chemicals, what materials made up the ice itself.

 

So you'd want instruments that could tell you a lot about the types of material, the content of the ice itself. So you'd probably want to take real scrapings or little - a drill bit to drill in and get a sample out of it that goes a few inches deep, you'd want the ability to reflect lights off it to see how it reflected light, you'd want something clear away dust that might be on the top of it first, so you'd want to get to the ice itself. Those are instruments that you'd want to tell you more about what the ice itself is made of.

 

Beyond that, you may want instruments that help you determine the best way to get across the ice. Water ice, we know is very slippery. Maybe there are the things you'd want to measure about the surface conditions that you could move your rover somewhere else and that would take a very different type of instrument potentially.

Sherri and Chris shown together on screen.

Sherri: Okay. Well Chris, we want to thank you again so much for spending this time with us today and helping us work through some of these obstacles. We want to remind everyone out there that your project due date is March 1st and there will be the big Web cast on March 2nd, so we do hope that - I mean on May 2nd, so we do hope that you return with us and join us for that. Also, many of you, we weren't able to answer all of the questions that were submitted today. There will be an FAQ page on the Quest Web site as well as this broadcast being archived so you can go back and review it more carefully if you thought you heard something earlier that you want explained to you again, you can launch that off of the Quest Web site.

 

Again, we want to thank you for joining us. We wish you the very best of luck. Thank you for participating in the Space Day Web cast. Have a great afternoon, all. Bye bye.

 

 
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