Sherri: Good afternoon to all of you out there in worldwide web land. Welcome to Johnson Space Center here in Houston, Texas. We have a very special Webcast for you today. We have a guest named Rodney Rocha and we will be meeting with him in just moment. But we want to thank you for joining us. Our topic today is going to be on astronomy and more specifically we're going to be talking about the Hubble space telescope and all that it’s brought to us here on Earth. And on behalf of the Business Learning Outpost and NASA Ames Quest Program, we do want to welcome you.

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My name is Sherri Jurls and I will be your host, and without further ado I would like to welcome our very special guest Rodney Rocha.

Now the biggest thing Rodney about you is that you're an amateur astronomer, but Rodney is a native Texas and he hales from Corpus Christa and he got his bachelors in aerospace engineering from the University of Texas at Austin.

I'm an Aggie myself so we have some issues there but has a masters degree in physical science and space science from the University of Houston in Clearlake.

He currently is the chairperson and the technical manager of the space shuttle [loads] and dynamic panel. He's also, if that wasn't enough, the chief shuttle engineer representing the Structural Engineering Division.

But again, the greatest thing about him is he's an amateur astronomer. He fits perfectly with our subject today. Rodney, welcome.

Rodney: Well thank you very much. I'm glad to be here.

Sherri: Will you take a few moments Rodney and, I gave a brief introduction, but tell a little bit about the kinds of things that you do, how you wound up here and that sort of thing.

Rodney: Certainly. Way, way back 28 years ago, long time ago, I decided to apply for working at NASA. I applied at other aerospace companies too. I graduated with an aerospace degree from the University of Texas. I knew since I was about 13 years old that I wanted to do something with America's space program. I knew that NASA too was whatever benefits would come out of NASA would help the whole world. I had interest in astronomy starting about third grade. That's a grammar school maybe for the rest of the world. I just kept up that interest the whole time, and here I am.

Sherri: Well my goodness since third grade. Not many of us know from such a young age what subject matter interests us so much that it will lead us on a career life path. Well I believe Rodney that you have some information today on the Hubble that you're going to share with us.

Rodney: Yes.

Though I'm an aerospace engineer and we have our own technical responsibility in areas that are not necessarily strongly related to astronomy. My interest in astronomy is a distinct advantage to help me understand our missions.

We just completed a shuttle mission to maintain, do maintenance and repair of the Hubble space telescope. We generally get into other types of endeavors too like building the space station. But I've always been especially interested in continuing the upkeep of this very valuable eye on the universe called the Hubble space telescope.

I would like to kind of go back, you saw a video of it being captured, capturing meaning that our spacecraft or space shuttle moves slowly, that is with respect to the telescope it looks like it's moving slowly but both objects are actually going five miles per second. And when you saw that silvery cube that was in orbit as the shuttle approached, it had these solar arrays or wings, if we had x-ray vision like Superman, you could look into that tube and you would see a mirror.

I brought here a little mirror that I use in the bathroom; it's a cheap little mirror that one can get at any drugstore.

But telescopes either use lenses or mirrors or both. I would like to illustrate little bit about how that would work.

On the top left that illustrates a telescope, if you were to take away the tube just look at the insides, that's called a refractor because it bends or refracts lights. It goes through a big lens to capture light and it focuses to a little bitty lens, which magnifies it, then it goes into your eye.

But the Hubble space telescope uses mirrors. So look at the bottom right, you'll see a mirror that if we cut it, a cross section of it, it has a strange shape or it's a sag or a depression in the mirror. It's a very special mathematical shape.

So that little object, that little red star like object, we can pretend it's a star. It travels from billions of miles away, or millions of light years, thousands of light years, hits the mirror, captures that light ray and then sends it back to another little tiny mirror or a lens and your eye would be there watching it.

But you don't have to put an eye there. You can put a camera, you can put a recording device

and that's what the Hubble space telescope really does. It's just really a fancy one of these kinds of mirrors but huge, it's several feet across or maybe a couple of meters across.

I would like to share with you some of the things that Hubble discovered for us. We could spend hours here talking about, going on and on and on, but there are a few things that I think are worth mentioning. There is a summary of things that Hubble has told us that were very, very exciting.

One of them, and there is a picture I would like to show you called the, it's a picture that shows many dozens of galaxies in what's called a gravitational lens effect.

All of these objects you see in this view are not stars. Normally if you point a telescope or camera to the sky, you'll just see so many objects amplified by the light gathering power of the scope, but these are galaxies and you'll see some arcs. There's some funny like streaks through there, if you kind of drew a circle around them, they'd make some sort of funny circles.

But these arcs, those are distorted light coming from galaxies from way beyond this cluster. Professor Einstein and his theory of relativity said that if you put enough mass between you, your eyeball, and a distant object that's way, way beyond this mass that's in the middle, in this case it's this bunch of galaxies, bends the light like a lens. So we're looking not only at those galaxies that are close to us, those streaks of light, those arcs are coming from galaxies even more distant. And the galaxies in front are bending that light.

It's just amazing. The other thing that Hubble has found and when I say Hubble I mean the telescope, it's discovering that our universe is not only exploding, called "the Big Bang," I think most of you have been reading in encyclopedias or books or magazines that a long time ago, maybe about 10 billion years ago the universe started as a hot point of matter and energy and then exploded into space.

It's still rushing away. All that matter and energy are still rushing away. Scientists used to think, they thought there were only two ways, what is the ultimate end of the universe. That had two answers. One is it slows down and stops and then comes back to a point and that's called "the Big Crunch." Or it keeps on going forever, it's slowing down, slowing down, slowing down but it'll never stop.

Well Hubble said both of those are wrong. They never guessed what the truth, there was a third answer. And that is it's speeding up, it's not even slowing down. There's a mysterious fifth force. Einstein called it "the cosmos logical constant." If you're a quantum mechanisian in quantum mechanics it's called vacuum energy density. Other cosmologists who deal about the origins of the universe give it a name called "the Quintessence," the Fifth Essence, the Fifth Force. We don't understand it all, we just know it's happening.

I want to share with you another picture. This is another Hubble picture taken a few years ago. Normally when you look at spiral galaxies they look kind of like whirlpools of gas that have arms. This one, something very wrong happened. The picture on the left shows that this galaxy lost its arms. There's a ring of bright gas and stars and there's a core at the very center.

The picture on the right is if we focused in on that little core and blew it up, what happened to the arms. It turns out that out of view of this picture another galaxy hit it just like a bullet hitting a bulls eye, it went through the center of this galaxy, went through it and went out the other side. And it destroyed the arms of this galaxy, and in the process it sent shockwaves throughout this galaxy that you see in that left-hand picture and started new stars to be born out of their gas.

Stars are born in our galaxy and all galaxies, but in this particular case there's more, an abnormal number of stars getting started out of the cold gas. They ignite, they form fusion, which is an atomic process to form heat and energy. This is a very unusual type of object.

In this picture, on the left, we see another explosion in process. It's called a crab nebula. Maybe it sort of looks like a crab when you see all those gas filaments in it. This is a star, maybe you have seen or heard the word supernova in movies or television, science fiction film, they're not science fiction. A supernova is a very large star at the end of its life, much, much bigger than the sun, much more massive. And it can no longer sustain itself by nuclear fusion, this atomic process. And gravity then takes over since gravity will now crush it.

But as it's being crushed the star somehow rebounds and explodes and throws all, or most of its matter, back out into space into a huge explosion. The Chinese here on Earth recorded that event a thousand years ago.

They actually saw it, they wrote about it and it they said a guest star has appeared in the sky in the constellation we call Taurus the Bull, and of course the Chinese then didn't know anything about Taurus the Bull. They had their own names for their constellations; they used their Chinese names.

They saw the star, and for months it was so bright it was visible even in the daytime. Today you need a telescope to see what's there. You can't see any explosion with your eye or even a telescope but the Hubble can see it and other large telescopes can see it. At the very center of that cloud is a city-size little ball of neutronium, we call it a "neutron star."

The picture on the right is a close up, the Hubble has peered into the heart and it's also called a "pulsar," it's rotating very fast, it's emitting light rays, I’m sorry, radio waves into space and we can hear them. It's kind of like a radio beckon, so we can beep, beep, beep, a powerful blast of energy. And a neutronium star or neutron star is a very odd object.

It's not a black hole, and like I said it's about the size of a city, maybe 10 kilometers across, and it's a pure crystalline star. The outer surface is a pure hard crystal, the hardest substance ever known. And physicists love studying these things because it tests their theory. How can we explain these things. And they're trying to, they're pretty successful at it.

I'd like to show you another picture.

This is a called a deep space view or you know if you put a telescope, a very powerful one like Hubble and looked at you're always going to see stars. But astronomers said you know there's a little blank area of sky in the northern sky near what we call the big dipper, it's more properly called Ursa Major or the Big Bear. They said this is a window outside of our galaxy, it's an area devoid of stars and they capture these galaxies.

So again here's some objects that you can see look like disks or little ragged pieces of gas, and there's tinier ones that look like stars. There are no stars in this photo. Well I think there is one here that got in the way, but nearly every object here is a galaxy. And remember, galaxies like ours, we live in one called the Milky Way, we maybe have 100-400 billions stars. That's a lot, I can't count that high.

These galaxies are about the same size. Some are bigger, some are smaller, but there may be hundreds of billions or trillions of galaxies in our observable universe, and this picture just,

here's a great picture of a nearby one. This is a spiral galaxy called the Andromeda galaxy. It's fairly close to us, maybe only two million light years away, ha, very close. That means the object you're seeing here when this photograph was taken not very long ago, the light left two million years ago.

It turns out you can see this particular galaxy with your own naked eye, in a fall sky, if you're in the dark country sky away from the city, you know exactly where to look, you'll see a fuzzy object and it will be this galaxy.

Well I have one more and this is my last picture here.

The Hubble space telescope is also keeping track on the planets and what's going on in our own solar system. That's our backyard. This is a ringed planet and I think some people would say oh I know it's Saturn. No it's not Saturn. Oh well it's Jupiter, Jupiter has rings, no it's not Jupiter.

This is the eighth planet Uranus and it too has rings. Only Saturn has those broad shiny rings, the other planets like Jupiter, Uranus and Neptune have darker rings. They're more mysterious. We haven't figured out why planets have rings. They should have disappeared. They're not stable, they should have disappeared millions of years ago, but somehow the planets don't know that and they keep forming the rings, they still feed the material.

That's one of the great values of Hubble is

it lets us, it not only discovers new things but it lets us look in our own backyard at planets and see what's going on. There's weather processes, there's giant lightening bolts happening on Jupiter, there's a Aurora happening on the planet Saturn and other planets.

The Aurora Borealis just like we see here and if you far enough north or south on the Earth you see those.

I think it's one of the most valuable instruments and inventions ever made.

Sherri: Well Rodney, thank you so much for that brief overview. I certainly have a much greater understanding of the Hubble and the things that it's helping us discover, and I think now it's time

to go to take our web viewers questions. We've already received quite a few. We'll start with those.

Well Rodney the first question we have comes in from Judith, and she wants to know why you like astronomy so much is that really why you wanted to work for NASA?

Rodney: It got me started. When I was in third grade and growing up, I knew I wanted something to do with the exploration of the universe. Later I became interested in engineering, and I think engineering is about how things work and how we can make those things work for people. We take what scientists learn and the principles and laws and physics, and we make things or invent things that will help people. I think that's what engineers do.

But astronomy's always at my heart because it addresses the mysterious, there are mysterious energies out there, mysterious things that scientists still cannot explain. They may have a theory, they don't even know if they're halfway right, and it's like what's on the other side. It's like living a valley all your life, you know that there's lightening flashing or mysterious lights in another valley and you want to climb out of your valley over that mountain and see what's there. I always want to know what's there. I think that keeps me excited about astronomy.

Sherri: Our next question comes in from Corey who is a 7th grade student in Florida. Hi Cory, thanks for writing all the way from Florida. He wants to know, do you know much about the Van Allen belt. Where exactly are they?

Rodney: Well and that was Judith?

Sherri: That was Cory.

Rodney: Cory. Cory. Good question. The Van Allen belts are not very [high]. They're part of our I think, I'm not a planetary scientist so I just saying, I'm hoping I'm being accurate from what I've read. It's part of our ionosphere. They're charged particles trapped in a cube. If you imagine a donut around the Earth, there's a lot of radiation and a lot of charged particles there. They're trapped by the Earth's magnetic field.

And these particles come from space, from the sun, a lot of charged particles called the Solar Wind come from the Earth, the Earth traps them into this tube. We didn't know it was there until about 1958, that's when the United States launched its first satellite called Explorer I. Of course one year before the Soviet Union launched its satellite first, ours had an instrument aboard Explorer I that detected the Van Allen belt.

You wouldn't want to stay there. They're pretty high above the Earth, I mean shuttle orbits, it's above where the space station is flying, above where the shuttle's flying, where other countries like Russia fly. But if we were to fly that high, and maybe it's a thousand miles or so, I'm not real clear on that, but I know it's much higher, you wouldn't want to be there because of the radiation. But luckily we fly safely underneath it.

Sherri: Floyd thanks for your question. You write in and want to know if Rodney has a favorite planet?

Rodney: Yes Floyd. Of course I'm going to leave out the Earth. I mean without the Earth where would I be, I wouldn't be here talking to you. And this is why I earn my paycheck and where I have all my friends and family. So okay we got the Earth down.

But what planet off the Earth do I like the best? Well last year when I was completing my masters degree I did a research paper on planetary rings, and I just fell in love with Saturn all over again.

Yes, I like Mars because it may have frozen fossils and water maybe that's where we're going to explore next.

But Saturn and its rings, the beautiful broad rings, they're still a mystery. It's the only planet that if you had an ocean big enough it would float.

It's less dense than water. We can't say that about other planets.

If you had a giant ocean it would be floating. Of course I don't how those rings would stay in place.

But I think the rings even though other planets have rings, there's nothing to compare with Saturn's rings.

Sherri: Well I agree with you, Saturn is a beautiful planet, but also like you, I think Earth is my favorite. It's just beautiful. Okay, Margo wants to know how long has the Hubble been in operation.

Rodney: Well let me first say Hubble, there was an idea for Hubble that started in the 1970's. Before the space shuttle was fully designed there were ideas to design a powerful space telescope. That was the first name, it was just called "the Space Telescope." I worked on that project also.

And later, it was given a name of the famous American astronomer, Edwin Hubble. Dr. Edwin Hubble discovered in the 1920's, he took many photographs of galaxies that are far, far way from our galaxy. He discovered that the far away galaxies are rushing away from us like there was a great big explosion. That's called "the Big Bang" today. He didn't call it that, he didn't even know what was going on. He wrote these papers, presented the evidence and he said I've discovered something very odd, all the distant galaxies are rushing away. It's like there's an explosion.

And they even named a law, there's an equation you can write in math that describes if it's far away, this much, then it's going away this fast and that's called Hubble's Law. So that name we honored him by giving that to the space telescope, now it's called the Hubble Space Telescope.

It was launched I think in 1989. I'm not sure, I think it was springtime, I'm really, I hope I'm within a year of it, either '88 or '89. Now we discovered pretty soon that there was a flaw in the optics. It still worked,

we were getting light images but because of an error in assembly, in the manufacturing, we needed to go up with another mission, a few years later, put some more optics in there, like I'm wearing glasses because I cannot see very clearly without my glasses and Hubble's vision was a little blurry too.

We made special lenses and put them on. Now Hubble can see clearly. On the last mission that just occurred, just a couple of weeks ago, and you see an astronaut here putting in an electronic box, maybe it's part of the control system or computer, it even has sharper vision and Hubble's not only see invisible light, our eyes see what’s called "visible light," we see all the colors of the rainbow, white light and so on.

Hubble cannot only see that it can ultraviolet light and you know there are other animals on the Earth that can see ultraviolet too, they're bees, the bees can see. They can always see the sun in the sky even on a cloudy day.

Rodney and Sherri on screen

Sherri: Well I'll be I learned something new today Rodney.

Okay, Wade is a 6th grade student from Florida, and he wants to know why is the Hubble so important. Can you give us an example of a couple of things that it has discovered or proved.

Rodney: Yes. I'll stick with my first example. Remember when I was giving the presentation. That was a discover that, the big bang, this big explosion is not only, it's not slowing down, it's actually going faster. There are some physicists that have theories on that.

That's one of the major discoveries that the universe is accelerating, going faster and faster and rushing away even faster. The other big one, we could say well yeah what about all those pictures of planetary nebula and this and that. Those are great but if I had to summarize it to two things, that's one thing.

The other is we discovered that most, if not all large galaxies at the very core, at the very center may lurk giant black holes. Not all physicists believe in black holes, they think there might be other explanations. Massive objects with gravity, like this is an artist’s illustration,

this is not a Hubble picture, this is a computer graphic. This is an artist. The object on the right, pancake looking disk or it looks like a crepe suzette or a disk, at the center of that is a tiny, tiny little dot, and swirling around it and falling into it is gas. And that black hole is stealing gas from its orbiting star.

See that blob on the left, it looks like it's pinched. It's got a point. The black hole on the right is stealing gas and there's a little filament, a little bridge that connects the two, it's crossing that bridge and sucking that matter around and around, going millions of miles an hour until it finally disappears into that black hole.

The discovery of Hubble, one of the biggest is that nearly every large galaxy including the Milky Way has a huge black hole. And by the way we wouldn't want to go near a black hole, part of it is we, the movies have told us oh that gravity will pull you in. Well no, even if you're far away from one there's deadly radiation, x-rays, gamma rays, it's not a nice neighborhood.

Sherri: Well thanks for the tip, I won't go near one. Okay, the next question we have is from Ryan who is an 11th grade student, and Ryan wants to know how much longer do you think the Hubble will be in use?

Rodney: Well I think the Hubble will be around, its systems are doing very well. It's got brand new components, new solar arrays, better computer, sharper eyes. It ought to be around for years and years. I hope ten more years at least.

Now if the public, the American public who pays taxes and we get our money from the American public that endorse the Space Program and Congress too, they have to decide. We can keep Hubble up as long as we want to keep paying for keeping it repaired and working and when we have new computers and new cameras and things wear out, we can just keep it up for a long time. I think decades.

Now there are plans for another type of telescope like the Hubble. It's going to be a little bit different; it'll work in infrared light, not just visible light but infrared to make other kinds of observations. And that's being talked about now by NASA, and we're talking to the U.S. Congress about it. But I don't there's any limit.

Sherri: Well speaking of repairs Rodney, Lorna writes in and wants to know how many times has the Hubble been repaired or upgraded up to this point. Kind of a specific question, isn't it.

Rodney: Yes it is. I may be wrong but I think if my memory serves me maybe this is the third or fourth mission. I think the very, the first mission put it up. The second mission went up there to correct its blurry vision, and I think there's been at least two more, what we call servicing missions. My best estimate is we've done it at least four times. And I think we're planning a fifth one also.

Always to keep improving it. We're not necessarily fixing anything. There's nothing wrong with it now, but you know what happens in a couple of years you have better computers, you have better cameras, we have better solar arrays that can make more electricity. That's one of the improvements here, we put on better solar array and it has more electrical power now.

Sherri: Robert writes in, has the Hubble ever found evidence of other life past or present anywhere?

Rodney: No not yet.

A long time ago, remember I talked about the crab nebula and the Pulsar. There's a rapidly spinning neutron star shooting radio waves out. That was back in the 1960's, now there was no Hubble space telescope then. Scientists at first couldn't explain it, and they thought maybe there's intelligent beings sending radio signal at us. Later we found out that we had a better, I mean we had a theory for neutron stars, and we were able to explain that.

But, no, the Hubble has not seen that. It's really not part of its mission right now. There are other projects that are called the SETI, you may have heard of it called, it's an acronym, SETI, Search for Extraterrestrial Intelligence. I think it's, it used to have a lot of government funding; it may have more private funding now and from universities. And they're listening, they're always listening, listening, listening.

Now of course one day we're going to go to Mars, and we may be the United States and may be with the Europeans, the Japanese, the Canadians, the whole world, we may have a world space program going to Mars.

And Mars may be where we'll actually have to go and find the evidence of microbes because I don't think any scientists think that if there was life on Mars, it probably never was bigger than micro, that is like germs, bacteria, viruses.

Some, and here's a picture of a photograph, that's a nano fossil maybe. I’m going to say maybe because scientists here at Johnson Space Center used an electron microscope to blow up a tiny section of this meteorite, found in Antarctica. This meteorite may have, they feel very strongly, it came from Mars. There was some terrible big collision on Mars, like a big asteroid hit it, and the pieces flew off Mars and they hit other planets sometimes.

One of those pieces traveled all the way to Earth, maybe 20 thousand years ago and landed in Antarctica.

Scientists today or very recently cut it, sliced it up, looked at it with this powerful microscope and said those look like nano fossils like on Earth because there are some fossils that look like this. Other scientists say, no, that's not, that's a natural process, that's not life, bla, bla, bla. We don't know. Our experts say we cannot say, we don't have any other explanation, it's got to be a fossil.

Others say let's wait till we get there and prove whether or not that's true.

Sherri: We've got a 5th grader writing in from Georgia. Her name is Melanie

and she wants to know how the Hubble got into space.

Rodney: How the Hubble got into space. Well the space shuttle took it up.

It was designed, the Hubble space telescope was designed with special features, mechanical features so it could attach to the inside of the cargo bay of the space shuttle.

Now here you see a space shuttle mission taking off. In the part that looks like an airplane, it's got the wings and tail, there's some big doors on its back, on the top, these big giant doors open up. They're big rectangular doors and it reveals a cargo space, a volume where we can put in large cargos or payloads or instruments like the Hubble space telescope.

The Hubble space telescope is very large. I'd say it's almost 14 feet across in diameter. What's that about greater, almost four meters and it's very long, I'm going to guess 50-60 feet long. And of course it had to unfurl those solar rays later after we let it go but we took it up there, grabbed it with a robotic arm. It's controlled from an astronaut on the inside of the shuttle. This is when we're in orbit, gently, gently, gently, let it go, and we commanded the shuttle to move away from it so we wouldn't disturb it, and then let it fly in orbit by itself. Then the shuttle came home to land.

So, it was a space shuttle that took it up. And it can only be brought up or down on the space shuttle. If one day we had to bring it down, we could bring it down.

Sherri: Well tied in with that Chris writes in and wants to know when they have to do repairs on the Hubble do they bring into the payload bay of the space shuttle to work on it?

Rodney: Yes they do. I was explaining to a friend of mine the other day that very question. You'll see in some of the videos that the astronauts are working on the telescope. We have to capture it first, with this robotic arm, we have to match orbit.

So we have, we're flying together above the Earth’s atmosphere in space, maybe 300 miles or so above the Earth atmosphere, above the surface of the Earth, capture it with this robotic arm and gently bring it into our cargo bay. That's that big empty space in the back of the shuttle, and there's no air back there. We don't pressurize it, that's what I had to explain to my friend. It's still in the vacuum of space.

So we go in, or the astronauts that are trained to do this, go into an airlock, get into their spacesuits, get all their tools and lights and other contraptions and everything they need and go out into the cargo bay. So it's like going, even though we say we're going out into the cargo bay, it's like going out into space, there's no air back there. It could be very hot or it can be very cold and sometimes you get both at the same time.

And they have to work with their gloves and spacesuits and it's very hard to do because they sometimes have to use screwdrivers or other instruments that are very hard to use. But yes, it's all done in our cargo bay and to keep the telescope from floating away it's attached to a special table.

Sherri: Mike writes in and wants to know, the shuttles had problems during the Hubble mission. Can you explain the problems they had and how they fixed it.

Rodney: Well let's see I don't think we had very many problems with this mission. There was a little bit of, a minor problem on the shuttle itself, called a Freon coolant leak, but a lot of our, and what that does is gather waste and heat from the computers and the electronics on the shuttle. You always have waste heat and if you don't do anything about it to take it away, like to use heat transfer methods to move it and dump it into space, your computer or your system will just get hotter and hotter and hotter and then it will fail.

So we use Freon lines and they're in loops, you might get an idea of what this looks like if you look on the back of your refrigerator or an air conditioner. It's getting rid of waste heat too. But we had a backup system so there was really no problem.

As far as the space mission to repair the telescope, the suits worked well, their tools worked well, everything seemed to go very smoothly. They did all the five space walks. I think there were very, very minor problems.

Well let's go on Rodney to our next question and Paula wants to know do you use astronomy while doing your regular NASA job?

Rodney: Yes I can say I do. And that's not true for everyone because amateur astronomy is a hobby of mine and it's not true that if I ask every NASA aerospace engineer and I'm an aerospace engineer, I sometimes am shocked at what they don't of astronomy. They may be very expert in what they do. They may be excellent designers or they can do this analysis and complex mathematics, but not everyone knows about astronomy, not everyone has the same level of interest that I do.

Now I find it's an advantage because way, way back in the 1980's we were designing concepts for a space station. What we see today is the mature design and the one we're actually building. But it helped to know about, like orbital mechanics, that is how to compute an orbit. It helped to know about solar radiation, how to design for that. You could go to other experts to get that information, but it really helps if you knew a little bit about it yourself so you could get started.

Because a lot of our engineers that knew astronomy or a little bit about it, it helped us to understand to design the system a little bit better. Whenever we send space probes to other planets, like to Mars or Mars Odyssey for example, or the [Casini] spacecraft going to Saturn, it helps in my astronomy to understand how planetary orbits work, or how it's going to enter a new orbit. Or how in the world do they fire an engine to make it descend and control itself all the way down to the surface. And my study of astronomy has helped me in that area and I think it, I've taken advantage of it, yes.

Sherri: Sounds like you use it in a lot of way. Well we have received a question from a 9th grader named Timothy at Lamar School, and he wants to know how strong a telescope is needed to actually see anything to make it worth your while.

Rodney: Well I'm thinking you're thinking of getting a telescope or buying one. Some amateur astronomers make their own. They have kits that they put together, they can buy their mirrors. And of course, they can be little mirrors like this or they can be much bigger. I would suggest starting to look at astronomy magazines. There's a couple of extra ones and there's more than two, but the two very popular ones, one's called Astronomy Magazine. You can find them in most bookstores.

The other is Sky and Telescope. And there's other ones, but you'll see these two, Astronomy and Sky and Telescope. They're loaded with ads, they're loaded with kits, mirror kits and you'll see articles in there talking about how to buy a telescope.

But all right let's say you don't have that magazine yet. I'll tell you what not to get. If you go into certain department stores or camera stores, you'll usually see a little skinny tube with a tripod, and they'll say 400, 500 power telescope. Don't get it. Those are going to be very disappointing. My recommendation is to like check those magazines, get a catalog from those ads that are in there.

I would suggest if you're going to begin in astronomy, get a reflecting telescope, maybe a three inch mirror, you know it's about this big, big around like this. Maybe a six inch mirror which is about this big around. The mirror is like the Hubble space telescope, that's what it uses. At the bottom of the tube is a mirror. Mirrors are cheaper than s lenses. The ones that use lenses up at the front, they're very expensive.

And for an amateur, if you want to look at the moon and planets, that's what usually amateurs start out looking with, you want something that's cheap, cheap enough but good, will show you some nice images and won't cost you a lot of cash. And it will be fairly dependable. I suggest a three inch, a four inch diameter or a six inch diameter reflecting telescope. There's many, many ads in the magazine. Maybe your local town may be selling some in a camera store but again, don't buy the skinny little tube with a lens up front and it says extremely high power.

Power is not what astronomers want. You want low power and bright images. And those magazines or books at the library will help you with that to learn more.

Sherri: All right, Ernest wants to know what's the neatest thing you've every seen with your telescope in the sky.

Rodney: I think I have an easy answer to that. Now I've been watching, I have my own small telescope at home and sometimes I borrow other friends of mine telescopes. I belong to an astronomy club in Houston. There's several hundred members in it, so I get to look through very giant telescopes.

But my small telescope at home and that's a six inch diameter. The mirror's six inches in diameter, it's a Newtonian designed telescope meaning Sir Isaac Newton invented this type of design over 300 years ago. It was when the comet Shoemaker Levi was hitting Jupiter, pieces of that comet, the comet had broken up, you may have read about it, you can read about it in I think most of the encyclopedias.

This is comet Hale Bop but let's say this type of comet comes to close to Jupiter or a giant planet like Saturn or Jupiter. If it comes too close it can break into pieces, that's what happened with comet Shoemaker Levi, it broke into a dozen big pieces, and then it swung around the sun one more time. One year later all the pieces hit Jupiter,

bang, one at a time, bang, bang, titanic explosion.

Well I could see it from my backyard. I pulled out my telescope, the whole world was watching with their big instruments, the Hubble space telescope was looking, Galileo was looking, a spacecraft that was going to Jupiter, but from my own backyard I could see the smudges on Jupiter.

And of course you wouldn't want to be there when those pieces of comet where hitting it because those were bigger than any atomic weapons on Earth, just hitting that planet.

But I was able to see that live on my own telescope.

Sherri: Well Marie is a 6th grade student and she wants to know what kind of jobs can astronomers do besides teaching and working at planetariums.

Rodney: Well I think that's a big questions. There's so many things they can do but one of the things is do research. You might want to pick planetary science. I want to know about how to study the planets, its atmosphere, weather or life, that's called xeno biology, or xo biology. About life off the Earth, that's the biology of life off the Earth.

Planetary scientists also try to figure how planets form. When a star forms and there's this swirling gas [inaudible], how do they form a planet. You may want to be a cosmologists. Don’t confuse that with the word cosmetology, that's doing, fixing hair. Cosmology is the study of the cosmos. They study how the universe started and how it will end if there is an end.

There's stellar dynamicists, stellar physicists, they study about how stars form, how they burn all that fuel and how they die. Some become supernovas, some become a white dwarf. Our sun will become a white dwarf one day. You can read about that in a book, those astronomy books. There's many, many other things. Some study comets only, some study meteorites only. You can write papers or do research and study that your whole life long.

Sherri: So really all you have to do just follow your passion for whatever area you're interested in.

Rodney: Yes and if you make an exciting discovery it gets named after you.

Sherri: Well, Marie, I hope as a 6th grader you are considering a career in astronomy and hopefully this will give you some good ideas. Well Anthony is a 12th grader and Anthony wants to know what do you think is the coolest phenomenon occurring in the universe today?

Rodney: Well I think you mean cool meaning interesting, right? Because I could think, what does he mean? Cold, no, he means cool.

Let me see, the coolest thing. I think it's the study and search for the prove and evidence for black holes. Because remember I said that earlier in the show, not all physicists, not all astronomers accept that black holes exists.

The reason why I'm saying that because the theory says that all this matter gets crushed down to a point, to a perfect point of zero dimensions. And you know what zero dimensions means, that doesn't mean, well if I use an electron microscope I could see down there and I'd see something the size of an atom. No, they don't even mean that, they mean smaller than an atom.

It's like the opposite of infinity and some physicists and astronomers say I cannot conceive of that, that is impossible, there's something wrong with our physics and bla, bla, bla. So there's still a controversy going on. But you know what they can't explain their way out of it. It's like there has to be a black hole.

Well we're gathering the evidence. There's predictions they can make about black holes like how much, what kind of radiation comes out as it's being sucked in.

We're seeing that radiation. The Hubble has measured super massive black holes, or what we think they are, matter swirling around at the predicted speeds, at a million miles an hour, swirling around a little tiny object, and it's at the right speed for a black hole.

So there is evidence coming in. I'd like to see that confirmed or not. Yeah, that's exciting.

But now where does it go after it disappears, who knows. A lot of theories on that too. You can read about them.

Well we'll go on with our next question from Vera, and Vera wants to know which planet besides ours do we know the most about?

Rodney: Which planet besides ours do we know the most about? I'm going to rule out the moon because people say well that's not really a planet. It's the closest celestial body, our closest neighbor.

But okay, planet I'm going to have to say, Mars because we can see through the atmosphere. It has a thin, thin atmosphere. If you were standing on it you'd still need a spacesuit, but we can see it's not only near, we can see the surface and that allows us to have orbiting spacecraft like the Odyssey.

A long time ago there was one called the Viking Orbiter, and there's been many others and the Russians have sent theirs too.

I think we're just learning an awful lot about that planet that's very, very Earthlike. That something happened on Mars that turned it into a cold, dry, maybe a dead desert. Some think there's frozen water under the surface. Some think there might even be hibernating life forms, like microbes.

But that's the most interesting planet to me in that it has the possibility that there may have been life off the Earth. And there's other theories too that said we actually exchanged biological material between Earth and Mars. That's because way, way billions of years ago there was a lot of traffic, asteroids and comets smashing the planets all the time. We see evidence of that with all the craters on the moon.

There's craters on Mars and there were fragments flying all over the place and it wasn't a safe place to live back then. But today, all that debris has been cleaned up, part of that is Jupiter and Saturn, they've cleaned it up with their gravity. They've cleaned up the universe. We have to be thankful for those big planets too.

Sherri: All right well Steve wrote in and wants to know if there are best times to view the sky during the nighttime hours.

Rodney: Best times. Well it just depends on what you want to see. You can see the moon just any time. Now it looks slightly different, the contrast will be different when the sun goes down. The very brightest planets that you can see with your naked eye and then you can put a telescope on them, a small telescope will do.

You can look at Venus, Mars, Saturn and Jupiter. You don't need powerful telescopes that show you some fine views. You can see the rings of Saturn and it doesn't depend very much if you do it early in the evening or late.

Now, if you want to see something faint, like the Milky Way, you do have to wait until there's all the glow of the sun, the twilight is gone and get out of the city. You got to go to the country, get away from artificial lights. There's something happening worldwide called light pollution. Even the little towns have way too much light and it gets up into the sky, it reflects off all the particles and everything and it gives a sky glow.

Here in Houston where I live, I've lived here many, many years, and I cannot see the Milky Way here. In my hometown, it wasn't a very little town, but I could see the Milky Way easily. Now I have to get over a 100 miles away from Houston to see the Milky Way and I think that's pretty sad.

If I want to see a meteor shower, they'll be a definite time when it's best to see that. It may be at midnight, it may be three in the morning, but you got to pay attention to those astronomy magazines; the newspapers will tell you exactly when to look too.

Sherri: Well speaking of looking up in the sky, Melanie is a 5th grade student from Georgia and she wants to know is it true that we can see the Space Station without the use of a telescope?

Rodney: Oh certainly. It's very, very bright and will continue to get brighter as we add more pieces to the space station. You can look up, there's certain NASA Web sites that publish this information. They'll have information of the shuttle or Hubble space telescope or the Space Station and when they might be visible over your area.

You get online and I know, I don't have that information for you right now but you can type in there the city or country that you live and someone here has done all the calculations for you and will tell you exactly where it will appear, when. Now it's not going to be visible every night, I don't want you to get the idea because orbits, an orbit stays in the same plane all the time and the Earth is rotating underneath that orbit. So there's only certain times when an object like the Space Station might come over you.

But it will look like a brilliant star, and you don't need a telescope. If you look in binoculars that might show you an object even brighter. But you won't the object, you won't see a shape of the Space Station, you won't see a space shuttle, it'll just look like a bright, bright, bright, star. Oh yeah, but it's very easily visible.

Sherri: Well Rodney as a matter of fact when the station is finished being built it will be the second brightest object in the sky. A little piece of trivia I learned along the way. And the Web site that Rodney is referring to is: spaceflight.nasa.gov and please note there's no www in front of that. That is Johnson Space Center's main Human Space Flight Web Page, and when you go to that web page you can click on the tab at the top of the Web page that says real time data. And that will give you the sighing opportunities. This is what the Human space Flight Web Page looks like.

We'll give you the sighting opportunities for the Hubble. And as well as, I mean, excuse me, not for the Hubble, for the Space Station as well as the space shuttle if it happens to be up on orbit as well. So again, spaceflight.nasa.gov.

Rodney: One neat thing, sometimes you can see the two together. If there's a mission in progress, you might see the space station and the shuttle together. They'll be one right behind the other especially if they've separated. I've seen that.

Sherri: Well we have time for about one more question, I hopefully we got to as many of yours as you submitted. But Kelly wants to know if the links of days are different on different planets and if so, why?

Rodney: Yes they are. You said "days," but it turns out that days and the years are different. The day depends on how fast or slowly the planet is rotating with respect to the sun. So, if you're on that planet like Mars and you're looking at the sun, it rotates in about a 24 hour day. And you go oh well wait a minute, in the Earth it's about 24 hours and on Mars.

Therefore all the planets have 24-hour days. No, no, it just turns out to be a coincidence.

Jupiter rotates and it's the king and giant of the planets, rotates once in nine hours but it's so big it flattens. Look in this picture.

That's not a sphere, that's not a perfectly round ball, it's actually flat at the north and south poles because it's made out of gas. It's just a giant gas ball, there's no solid stuff in there. Now that's a huge rotation, that's a nine hour day.

And you have planets like the planet Uranus, it's rolling sideways. It's axis is actually turned almost horizontal and it's rolling sideways.

Sherri: Well thank you Rodney so much for spending this time with us this afternoon, answering all of our questions. We had a whole bunch.

Rodney: Glad to be here.

Sherri: I know you got through as many as possible. Thank you for submitting your questions and on behalf of the Distant Learning Outpost and NASA Ames Quest Program we want to thank you for joining, for participating in learning more about astronomy and the Hubble space telescope with the Web cast today. Please keep an eye out for future Web casts coming your way that you might be interested in. You can look up the calendar on the Quest Web site of all future events.

We appreciate your time and hope that you have a wonderful afternoon. So long from Johnson Space Center.

Rodney and Sherri waving goodbye.

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