Planetary Radio: Space Exploration, Astronomy and Science - Astropulse: A New Way for ET to Phone Home

Episode Date: September 15, 2008

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It'll be our little secret. One other favor to ask before we start the show. I turn Martian green with envy when I see all those other podcasts that get lots of reviews on iTunes and elsewhere. Could you take a minute to add your own thoughts about the show? I don't even care if you say nice things about us. And if you believe that, I've got a slightly used asteroid for sale cheap. Thanks so much, everybody. We love you, and we're grateful.

And away we go. A new way to listen for E.T. this week on Planetary Radio. to listen for E.T. this week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. SETI at home, it's still the biggest supercomputer on Earth. We'll talk to Chief Scientist Dan Wertheimer about the project's new AstroPulse

search and catch up with other news from the search for extraterrestrial intelligence. Bill Nye, the science and planetary guy, is back with more thoughts about the decommissioning of the space shuttle and human spaceflight plans elsewhere in the world. And Emily Lakdawalla returns to solve a counterintuitive puzzle at the North Pole of Mars. Did Bruce Betts eat that space food stick I gave him last week? The universe demands an answer, and it will get one, along with this week's Night Sky Survey and a new space trivia contest. There's news as big as space waiting for you at Planetary.org, including Emily's story about the Rosetta spacecraft's flyby of asteroid Steins. Check out her blog for even more.

You're going to hear Bill mention the Ares rocket in a minute. NASA has announced that the Ares I has just passed a preliminary design review. That's the first time this has happened with a human-rated American rocket in 35 years. Here's Bill. Hey, hey, Bill Nye the Planetary Guy here, Vice President of the Planetary Society. Let's say you're listening to Planetary Radio in English, and you're a voter, and you're a taxpayer. You might be in the United States, you might be in Canada, you might be somewhere in Europe. Here's the thing.

The United States has this space shuttle, and the space shuttle is getting old. You know, it was always really an experimental spacecraft, and she's wore it out. Now, the idea was to phase the thing out in 2008. They're going to have to take it out of service sooner or later. There's plans now to extend it because everybody's concerned that the former Soviet Union, Russia, concerned that the former Soviet Union, Russia and Georgia had this conflict and Russia now is going to have the capability of sending humans into space while the United States will not be able to, while a new rocket, let's say the Ares, is developed to replace the shuttle. So here's the thing. Is that a big deal? Does that mean that the Russian government will put legions of cosmonauts into space to watch the Earth and maybe they'll parachute down in some big army and cause a bunch of trouble? Or is it just another time when you can't use the space shuttle to get into space?

Meanwhile, there's a guy, Steve McClain, good guy, astronaut, flown a couple times in space. He is now the head of the Canadian Space Agency. There's a guy, Steve McClain, good guy, astronaut, flown a couple times in space. He is now the head of the Canadian Space Agency. Now, in the United States, there's no astronaut who's ever been the head of the National Aeronautics and Space Administration, NASA. That's never happened. And then the Europeans are planning to have a meeting in November to build their own human access to space transportation system, a rocket for people. So maybe this is fine. But while everybody's getting all wound up, just remember that the NASA budget is about a half a percent of the U.S. government budget. It's much, much smaller in percentage than it once was. The thing is that the prestige associated with space transportation and humans in space is somehow out of proportion to the amount

of money available. And see, because the budget is so small, not that many people pay attention to space exploration. But you do, because you listen to planetary radio. That's why we have this show. So as this election comes up, whether you live in the United States or not, I want you to think hard about the importance of the United States being able to send people in space. Is it a big deal or is it just one of those things? Well, thanks for listening to Planetary Radio. I'm Bill Nye, the Planetary Guy, and let's, dare I say it, change the world. Who can say how E.T. may communicate?

Will he come up with the same solution for calling on his interstellar neighbors that we humans might? That's a question Dan Wertheimer and his colleagues ask themselves all the time. Dan is chief scientist for the SETI at Home project based in the Space Sciences Lab at UC Berkeley. Maybe you're one of the volunteers who has dedicated your computer's downtime to helping the search for extraterrestrial intelligence, or one of the other gigantic data crunching efforts enabled by the pioneer and leader in massively distributed computing. I called on Dan last week so that he could tell us about a new SETI search called AstroPulse that has changed the rules. Dan, welcome back to Planetary Radio. You've been on several times. I discovered, I'd forgotten, you were one of our very first guests all the

way back in early 1983. It's a pleasure to have you back. It's an honor to be back. So how many people online roughly now with SETI at Home? There are about a million volunteers in SETI at Home. It's still the world's largest supercomputer, if you add up the million volunteers, equivalent to almost a million computers running continuously. Yeah, take that, Intel, which I just read is coming out with their first six- core processor. Pretty amazing. What I really hope we can spend most of the time talking about is detailed in an article by my colleague, Amir Alexander at Planetary.org. And it is

steady at home, but it's a new kind of search. And I guess it's because you guys started to think, you know, what if aliens don't want to communicate exactly the way we think they would? Yeah, I think that's right. Our idea is to try multiple strategies. We don't know what kind of signal ET might be sending. And instead of putting all our eggs in one basket and focusing at a particular frequency or particular kind of signal or particular place in the sky, we want to do a lot of different searches. And we actually have seven different searches that we're doing simultaneously looking for a variety of signals. And Astropulse is our newest signal type or newest strategy looking for these pulse signals.

Well, you caught me by surprise. We'll have to talk about some of those others because, really, all I knew about was what I guess was the original narrowband search, although I think that got even narrower a while back. But AstroPulse, in a sense, is the opposite of that. I mean, you're looking pretty broadly across that famous hydrogen band. Yeah, that's right. We think that if ET is sending a signal intentionally,

they will make that signal to be easily distinguished from something, a natural signal. The early ideas was that they would put the signal compressed in frequency. It would put all their energy at one frequency, and we'd just look at a lot of different frequencies, and if we found something at a particular frequency, just like kind of tuning your dial across the spectrum, across the radio dial, and if you see a strong signal at one frequency, that would alert us that there's something interesting there. But another possibility that we're pursuing with

astropulses is that instead of the signal being compressed at one frequency, it will be compressed in time. A pulse, just like a lighthouse when it comes around, gives you this flash. This would be a radio flash. And that's the kind of signal that we're looking for. And that is also easily And that's the kind of signal that we're looking for. And that's also easily distinguishable from natural signals. And you might argue that ET could just as easily be sending pulses instead of these continuous signals. Now, with the original search, you were down to looking at channels, if you will, that were really pretty small. I mean, quite a bit smaller than, let's say, what a television transmits to our homes. Yeah. So the early ideas was that you would look, since earthlings are sending off TV

and radio signals and radar, and maybe ET does that too. And most of what earthlings send are not pulse signals. They send these continuous signals. Television is always running. It's got a lot of power at a particular frequency, at different channels, at different frequencies. And so Earthlings do that. But now Earthlings are starting to do pulse communication, kind of blip, blip, blip. And that works just as well. Although the early signals were kind of compressed in frequency,

people are now doing pulse communication. And so ET can do that. And there's arguments back and forth about whether signals should be pulsed or continuous in frequency. And I think the best strategy is to look for both kinds of signals, both these pulse signals and continuous signals. In fact, we have two searches now looking for pulse signals, one at Arecibo, the AstroPulse,

and one at the Allen Telescope Array, the Fly's Eye Experiment. Arecibo, of course, being that still largest single-dish radio telescope in the world. And mention for a moment or two about the Allen Array and what's coming together in Northern California. Yeah, so this is a new way to build a telescope. It's kind of a revolutionary way to build a telescope. So Arecibo is this giant dish that a lot of you have seen in Contact or James Bond GoldenEye.

It's 1,000 feet across. It holds a billion bowls of cornflakes. That's the kind of traditional way to build a telescope, a huge dish to collect the signals. Now, the new way that we're exploring in Northern California, the Allen Telescope Array, and this is a joint project of Berkeley together with the SETI Institute, is to build a telescope out of lots and lots of little telescopes. Each dish is only 20 feet across, 6-meter dishes. There are tremendous advantages to build a giant telescope out of lots of little telescopes.

One is that it's actually a lot cheaper. You can stamp these dishes out like hot tubs. The other is that you can look at huge pieces of the sky at once. Arecibo sees a little tiny part of the sky, just a twentieth of a degree across. But these things can see, oh, hundreds of times more sky, an area a couple of degrees across, bigger than the moon. So it's very good for doing sky surveys where you want to cover big patches of the sky and survey the whole sky, look at lots of different stars and galaxies, because you can look at a big chunk of the sky at a time.

The other thing is that it's a scalable telescope. You can add more dishes as you get more money. So right now we have 42 of these dishes connected together, and we hope to have hundreds of them eventually. Let's go back to the AstroPulse search, or the two searches you said that you have now for pulses. I take it that really, if these pulses are there, whatever their source may be, you might have missed them all together using the traditional search for signals from ET. That's right. If ET was sending pulses,

nobody would have seen them so far. Very few people have looked for pulses. Ours is one of the first SETI searches to look for pulses. Other people look for pulses when they're searching for pulsars. There have been a few transient searches, but we're doing astropulses, by far the most sensitive one. And the reason it's so sensitive is because we have access to the world's largest supercomputer, thanks to all the volunteers, the million volunteers who are running SETI at home, are now analyzing data from Arecibo to look for these pulses. I'll be right back with Dan Wertheimer, chief scientist for SETI at home are now analyzing data from Arecibo to look for these pulses. I'll be right back with Dan Wertheimer, chief scientist for SETI at home. This is Planetary Radio. I'm Sally Ride. After becoming the first American woman in space, I dedicated myself to supporting

space exploration and the education and inspiration of our youth. That's why I formed Sally Ride Science, and that's why I support the Planetary Society. The Society works with space agencies around the world and gets people directly involved with real space missions. It takes a lot to create exciting projects like the first solar sail, informative publications like an award-winning magazine, and many other outreach efforts like this radio show. Help make space exploration and inspiration happen. Here's how you can join us. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members

can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. The SETI at Home project relies on the combined power of a million personal computers to take on some of the most complex computational problems imaginable. Chief Scientist Dan Wertheimer and his team have to come up with the algorithms that can work across all those processors toiling away all over our planet. He's telling us about one of their newest challenges, finding a message that may be compressed into a single, broad pulse of radio energy.

This new search is appropriately titled AstroPulse. I read the description of the kind of computing power that is needed to do this, and it's pretty awe-inspiring. And I guess a lot of it has to do with this temporal nature of the signal and the fact that as it reaches us, it kind of spreads out. Yeah, that's right. It turns out that in the old way, there was an unknown what frequency would they transmit on. And so we had to look at lots of different frequencies. For a pulse signal, you don't have to look at lots of different frequencies, but there's still an unknown that you have to search for called a dispersion. The dispersion has to do with how

far away the transmitter is. It turns out that it's not a perfect vacuum out there in space. There's electrons and other things out there. Things don't travel quite at the speed of light. The low frequencies get delayed a little more than the high frequencies. So when the signal gets to you, instead of sounding like a pulse, a blip, it sounds like a chirp. And that, because the low frequencies take longer, the high frequencies come first. And then the low frequencies arrive later. And so you get this chirp. But you don't know how much, you don't know the distance. So you don't know how long the chirp is spread out. If it came from a long way away, the chirp takes a long time. It's spread out a long,

if it came from a short distance, it's a quick thing. So we have to look for all those different dispersions, possible distances between us and the extraterrestrial civilization or the black hole or whatever we're looking for. And that takes a lot of computing. And to do it really well, we do something called coherent integration, and that takes the biggest supercomputer on the planet. But thanks to all the volunteers, we just happen to have the biggest supercomputer on the planet. You're not just whistling Dixie there, are you?

Is this working with the same data that has been processed in the previous searches, or do you have to pull down new data to look for these pulses? No, it turns out we can use the same data that we've been recording for SETI at home and just process it a different way. So we're sending out new work units to all the volunteers, and they process it with a different software, the AstroPulse client software, that runs on their home computer, on their screensaver, instead of the original SETI at Home screensaver.

We're still doing both. We're processing the data both ways. What else other than ET could you imagine, or can you imagine, anything else making these kinds of pulses? Well, there's a prediction that we might find primordial black holes. So when black holes evaporate, this was predicted by Stephen Hawking, black holes get smaller and smaller. They give off radiation. It turns out that the smaller they get, the faster they evaporate. And so at the end,

they're evaporating incredibly fast, and they go off with a big explosion. And that explosion would be in the form of a radio pulse, predicted by Martin Rees and Stephen Hawking. And those radio pulses, we would be able to detect at Arecibo or possibly the FLISA experiment. And then you'd ask, well, how big do the black holes have to be to be exploding right now? They have to start fairly small to be exploding right now, and the best way to do that is with primordial black holes, black holes that were made at the Big Bang explosion at the beginning of the universe. And some people predicted that there will be a variety of sizes of these primordial black holes,

and some will be evaporating right now, and we should be able to detect them with either AstroPulse or the Fly's Eye experiment. There is some evidence that somebody's already seen one of these giant pulses. This was a paper by Duncan Lorimer that came out last year. seen one of these giant pulses. This was a paper by Duncan Lorimer that came out last year. They found an incredibly powerful radio pulse. It came from more than a billion light years away. I suppose it's also possible that you might discover some entirely new phenomenon that nobody is even hypothesized about. Yeah, it could be. If we find some of these things, it could be ET. It could come from a black hole, an exploding black hole. It might be a couple of black holes colliding with each other or neutron stars colliding with each other.

Or as you mentioned, it might be some entirely new phenomenon. Nobody's really looked for these pulses in a very sensitive way. And so we don't know what to expect. Whenever you explore a new parameter space in astronomy, a new wavelength region or a new time region, or new places in the sky, there's stuff to find. And a lot of astronomy discoveries are made serendipitously. So we might find some new phenomenon. Hear, hear. Listen, speaking of black holes, I guess you just had an announcement come out. Yes, this was actually an offshoot of our SETI program. It turns out that

in SETI, people started using our instruments for lots of different things. We developed them originally for SETI, these electronics and computing instruments, and now they're being used at 30 different observatories. And we worked out with, using the stuff that we'd done for SETI, we worked out a new way to connect telescopes together that allows us to look at the center of the galaxy with unprecedented resolution. There's a black hole at the center of the galaxy, and we were the first people to use these new instruments originally that were developed with SETI and Planetary Society funding. We were the first people to actually see down to the event horizon of the black

hole. So this is the first observations of a black hole right down to the size of the event horizon. And so we're finally able to see down at the center of the galaxy what's going on. Wow. That makes me want to whistle in amazement. Are you still looking for volunteers? Yeah, the more the merrier. There's lots of data to crunch, and we're collecting more and more

with this multi-beam receiver together with a group doing pulsar observations, galactic and extragalactic. We have a huge amount of data from Arecibo, and the more computing time, the better, and we are really grateful to all the volunteers. What's that URL? And we'll post it at planetary.org slash radio as well.

Yeah, so you could just Google SETI, or the URL is seti.berkeley.edu. Dan, it's always a pleasure. Thank you, and as always, good luck in the search. Okay, thanks, Matt. Dan Wertheimer is the chief scientist for SETI at Home, the biggest computer on the planet. It's being used in all kinds of ways, including new ways to look for extraterrestrial intelligence. He's at the Space Sciences Lab at UC Berkeley. We will be right back with someone who's not very far away at all.

That's Bruce Betts for this week's edition of What's Up, but not until we've heard this week's Q&A from Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, I noticed that the air pressure has dropped nearly every day for Phoenix. Why is it doing that? Indeed, the pressure sensor aboard Phoenix recorded its maximum air pressure of 8.5 millibars on the day that the spacecraft landed near the north pole of Mars. Since then, the pressure has dropped by more than 10%, and it's still dropping.

This seems counterintuitive because it's late summer at Phoenix's landing site, so ice from the north polar cap is being heated by the sun and sublimating into the atmosphere, turning from a solid straight to a gas, which increases the amount of water vapor in the air. So shouldn't the air pressure be increasing? The reason it's decreasing has to do with a pole, but not the north pole. It's actually the south pole that's controlling Mars's atmospheric pressure. Down in the southern winter pole, it is so cold now that carbon dioxide is freezing out of the atmosphere. Carbon dioxide is the major constituent of Mars' atmosphere, making up 99% of Mars' air. So when carbon dioxide starts freezing, it reduces atmospheric pressure over the whole planet, even at the opposite

pole. Nothing like this happens on Earth because there is nowhere on Earth where it gets cold enough for nitrogen, the major component of our atmosphere, to freeze. The air pressure on Mars will continue to drop until the change of seasons brings sunlight to the south polar carbon dioxide ice cap again, liberating the carbon dioxide to return it to the air. Got dioxide ice cap again, liberating the carbon dioxide to return it to the air. Got a question about the universe? Send it to us at planetaryradio at planetary.org.

And now here's Matt with more Planetary Radio. We're out back with Bruce Betts at the Planetary Society headquarters because it's time for What's Up? He's the director of projects for the Planetary Society, about to tell us once again about the night sky. And how was that space food stick? That was good.

I was looking for a delicious, disgusting. Delectable. Oh, I'm glad you like it. It was quite functional a delicious, disgusting. Delectable. Oh, I'm glad you like it. It was quite functional. Oh, good. I was in the office. I was going to take your advice and throw it in the earthquake kit. But then I had it in the office one day.

And as you know, things get ugly when I get hungry. And it was late in the afternoon and I needed something. And there it was on the desk calling to me. Was it 10 delicious bites? Not for me. Well, I'll get two or three. I wondered if I had to eat it in 10 delicious bites, and I just was too hungry to care.

You probably violated some kind of NASA regulation. Yeah, there you go. What do you got? What's up in the night sky? Jupiter. Jupiter looking lovely, still in the evening sky over in the south to the west in the early evening. You can still try to check out those planets clustering down in the west after sunset. If you go out with binoculars, you can probably at least pick out Venus looking bright but competing with the light from the sun.

And, you know, don't look at the sun with binoculars. If you really are lucky and looking well, you can look below Venus and have a chance to see Mercury and Mars. Mercury being the brighter, whiter looking one and Mars the redder looking one, even dimmer and tough to see. And Mars, the redder looking one, even dimmer and tough to see. Also, if you're looking for a fun challenge and pull out the telescope, you can look for Uranus, which is at opposition. So the best time to try to see it, high in the south, southeast, early in the evening is probably the best place to look. You want to wait until it gets up a ways. You're going to want to use some finder chart. Go to the web.

You can find finder charts for that, but it is up there. This week in space history, Lost in Space debuted in 1965. I know, that excites me all the time. Danger, danger, Will Robinson, danger. Or was that Time Tunnel? I'm not sure. All those old 60s Irwin Allen science fiction shows that just blew me away as a kid. Lost in Space, Billy Moomy.

Thought it was Mummy, but it's Moomy. This is why I mention these things. Usually I stick to the science, but I know it excites you. Speaking of science, let's go on to Random Space Fact! Very nice. With Rosetta's flyby of asteroid steins that just occurred, I want to point out to you that spacecraft have now visited eight asteroid systems. Yeah.

And nine asteroids. We mentioned last week on this show that Emily has put together this great montage of those asteroids and the comets. It is. It's fabulous. I was actually going to recommend that again to people to check out. No, it's fine. In her blog you have to go back a few blogs. Go to her blog and go back a few. She's done a wonderful job putting them all at the same scale. It really is fascinating and let me tell you some things I extracted from that very image. The sizes of these asteroids visited range from tiny Itokawa, visited by Hayabusa at 500 meters by 200 meters, to Matilda at 66 kilometers by 44 kilometers.

Huge difference. Even Dactyl. This is something I had not realized even dactyl the moon of ida which is why there are eight asteroid systems and nine asteroids was bigger significantly than itakawa at 1.6 kilometers versus like 500 meters they're long edges so uh so there you go check out that image check out the the asteroids We always see them just in the black of space, usually, and it's hard to appreciate that there are a couple orders of magnitude difference in sizes. That was fascinating, but now we've got to get on to the trivia contest.

We asked you where in the solar system, and I asked you where is Tangaroa, but Lindsay Dawson, having grown up in New Zealand, has corrected me, so I'll give it another attempt with his assistance. Tangaroa. Tangaroa, which is what my younger daughter used to call her sister Laura. She still does now and then. Rora, rora, tangaroa. Tangaroa.

I think Scooby is an astro or derived from. That's right. Tangaroa. Anyway, where is it? Named after the Maori fishing and sea god. I had one thing in mind and apparently other people had other things in mind. Well, we threw you into the random

selection of the winner if you got either of these things. So what did they tell us? Well, Bjorn Ghetto was one of those who were in the majority that came up with what you didn't think we were going to get, which was Tangaroa is the Maori name of Neptune, which brings up an interesting philosophical point. How in the heck did they have

really good eyes compared to the rest of us? Clearly it was named later on. Anyway, what I was looking for is it's also the name of a crater on Neptune's moon, Triton. So either of those got you into the competition. Who won? Did I say? I thought I did.

Bjorn Getta? Maybe I did. Bjorn Getta, a Sweden regular listener. As far as I could tell, he has not won in years. But Bjorn, we're going to send one out to you real soon. Thank you very much. But Bjorn, we're going to send one out to you real soon. Thank you very much.

Here's Mike Pollard who sent the Maori names for all of the planets and one plutoid. In fact, that plutoid is in, and of course I won't pronounce it correctly, but that plutoid is Waringaki Tahiti. That's Pluto. Well, okay. Now, in that language, is it also the name of the cartoon dog? And the god of the underworld? How interesting.

I don't know. Maybe Lindsay will let us know. All right. Well, in the meantime, everyone try to answer the following trivia contest to win a Planetary Radio t-shirt. How many of the eight big planets, I'll call them, the four terrestrial, the four giant planets, how many in our solar system, those eight in our solar system, are known to have global magnetic fields? No, the word global magnetic fields.

Go to planetary.org slash radio, find out how to enter. You have until Monday, the 22nd of September at 2 p.m. Pacific time. All right, everybody go out there, look up at the night sky, and think about cardboard. Thank you, and good night. Bruce Betts is the director of projects for the Planetary Society. He joins us every week here for What's Up? Hey, same to you, buddy. It's Jupiter. Oh, yeah, I knew that.

Next time, a conversation with the late Carl Sagan's collaborator and life partner, Andrea. Planetary Radio a conversation with the late Carl Sagan's collaborator and life partner, Andrea. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week.