Planetary Radio: Space Exploration, Astronomy and Science - Gregory and James Benford on Benford Beacons for SETI

Episode Date: October 4, 2010

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Greg and Jim Benford on how to listen for E.T. this week on Planetary Radio. Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. It's no accident that they are called Benford beacons. We'll talk to two of the three Benfords who came up with a new approach to the search for extraterrestrial intelligence. Bill Nye the science and planetary guy will report on the International Space Conference he attended in Prague, the NASA budget vote in Congress, and another downside of living in space, lost fingernails.

Yes, ew. And down the line, I'll be joined by Bruce Betts, who will poke around the night sky in What's Up. About 200 scientists and engineers gathered in Monrovia, California last week for the fourth Mars Science Laboratory Landing Site Community Workshop. Our Emily Lakdawalla was there for much of the discussion about where the big new rover now called Curiosity should set down on the Red Planet. As she put it in her blog, none of the remaining site candidates were voted off the island. Emily, great reporting from that Mars Science Lander landing site meeting. There's quite a bit

to read there, but you seem to summarize it all in a couple of pithy statements, the first of them being, we don't have to guess anymore. We can actually see what the potential hazards are. Yeah, that was a pretty astonishing statement to come out of this week's landing site selection meetings. The fact that with HiRISE and CRISM and CTX, the three main instruments on the Mars Reconnaissance Orbiter, we can see every single individual hazard that might end Curiosity rover's life upon landing. But we can't target Curiosity that well, so is this just sort of looking across the region and averaging things out? That's right. They're concerned with things like what's the percentage of large rocks covering the landing area, the percentage of large rocks covering the landing area, the number of large rocks that might possibly cause the rover to high center, land on a big rock in the belly pan, and then not be able

to crawl away. And, you know, in the past, we've landed at landing sites like Pathfinder was one of the worst, where there was 20% rock abundance. 20% of the ground was covered with biggish rocks. The kinds of rock abundances we're talking about for the Curiosity landing site are fewer than one-tenth of one percent rock abundances. They're really tiny, so it's a really low risk. That sounds good. And is that true for all four of the sites that were being considered? Yeah, there's four landing sites under consideration, and all four are exceedingly safe. It's really amazing. Every single one of them would be the safest landing site in terms of the likelihood of the rover dying upon landing of any we have ever attempted or succeeded in landing at on Mars. This just makes me want to knock on wood though, but

are all four of them pretty much equally interesting from a science standpoint? Well, they all would allow the rover to address its main science goals, which are to search for evidence for past habitability on Mars, the kinds of ecosystems and environments where you could have tiny little critters crawling around in a nice watery environment that lasted for a long time. All four of them could address that, but they're four slightly different sites. A couple of them are alluvial fans where there's been a lot of material deposited from mountains. A couple of them are alluvial fans where there's been a lot of material deposited from mountains. One of them bears the signatures of clay minerals, which require water sitting around interacting with rocks to create new minerals. One of them is the largest stack of strata anywhere in the solar system.

It's kilometers thick, but the rover would have to land far away from that mountainous stack and then drive to it, which is a little bit of risk for the mission. All right, it's all there at planetary.org slash blog. Just a couple of seconds left to talk about what I think is one of the greatest discoveries regarding exoplanets yet, and that is this super Earth in the Goldilocks zone. I just can't get over the fact that 15 years ago, we didn't know if there were any exoplanets, and now there's like 500 of them. It is a very, very busy galaxy and lots more for us to look at out there. Emily, as usual, thanks very much. Thanks for having me, Matt. Emily Lochte-Wall is the Science and Technology Coordinator for the Planetary Society and a contributing editor to Sky and Telescope magazine. Back in just a moment with the Benford brothers, right after we hear from Bill. Hey, hey, Bill Nye, the planetary guy here,

executive director of the Planetary Society. And this week, Monday, started with the 4th of October. The 4th of October, everybody. The anniversary of Sputnik, the first satellite humans put in orbit around the Earth. Say what you will, that little machine changed the world. Well, this week was the International Astronautical Federation Congress in Prague, Czech Republic, and I was there all week listening to people talk about how we're going to use rockets

to explore other worlds, explore other star systems, explore our own sun, and learn more about the climate here on Earth. Very exciting. It's very exciting to see all of these people from all over the world sharing this vision for humans learning more about space and our place in it. While I was on the other side of the world, everybody was talking about the United States Congress, how it's passing the bill to fund the National Aeronautics and Space Administration, NASA, and who's going to do what about what. And sure enough, eventually, after all this arguing and this and that, the United States

House of Representatives passed essentially a version of the U.S. Senate bill. So they reached a consensus. Now, when you look at the language very carefully, there are some gray areas. That is to say, there's some twilight zone instead of a crisp terminator. But that's all right. Because what it means is, at last, the U.S. is moving forward. And that will almost certainly lead the rest of the world. The U.S. is finally going to shut down the shuttle program, finally declaring Constellation closed. What exactly is going to happen with this hardware they called Orion is not clear. But basically, the U.S. is moving forward, and NASA is going to move forward, and that's generally going to be good for everybody.

Boy, it's a difficult process, but they got through it. Now, along with that, I saw a little article about the gloves that astronauts wear. They're complaining that it tears their fingernails off. And I can tell you, I've worn the gloves when I was doing the Science Guy show, and they hurt. So who's addressing the glove problem? People from the other side of the world that I saw deliver a paper at the International Astronautical Congress. People all over the world are trying to make astronauts' hands more comfortable. It just showed me that even at this level, everyone is engaged in learning about our place in space.

So enjoy World Space Week, everybody. It starts with the anniversary of Sputnik on Monday, and it goes with events all over the world. Let's work together to learn more about our place in space so we can have a better world for everybody. I've got to fly. Bill Nye the Planetary Guy. How often do you see scientific papers published by twin brothers and their son-slash-nephew? James and Gregory Benford are the brothers. Dominic Benford is Jim's son. They have carefully considered the traditional ways of doing SETI, the search for extraterrestrial intelligence.

Their conclusion? That we may have been barking up the wrong tree for 50 years. Or would that be listening for barks? Jim Benford is the president of Microwave Sciences, Inc. and the author of the comprehensive textbook, High Power Microwaves. Greg Benford has been at the University of California, Irvine, for almost 40 years. The professor of physics is also a world-renowned author of so-called hard science fiction. I'm one of his fans. The brothers were last on our show to talk about microwave propulsion of spacecraft,

a topic we'll revisit sometime soon. Gentlemen, it is such a pleasure to have both of you on, and, you know, there are so many things that we could talk about, but we're going to stick to Benford beacons, this wonderful concept that the two of you came up with, with a little bit of familial help from son or nephew, as the case may be. Jim, that's your son that you can be proud of? That's right. He's an observational astronomer at Goddard Space Flight Center in Maryland,

and he made some good contributions to these papers and our concepts, and he did all of the complexated graphics as well. So he's not on the line with us, but he's with us in spirit. Greg, what may have been wrong with 50 years of looking for ET? Original, what we call classic setting, set out to look for continuously beamed signals around one gigahertz frequency, where cell phones work, that would be narrow band. And what Jim and I and Dominic showed in these papers is that that's very, very costly. It's not cost effective. In fact, thousands or millions of times more money than you actually need to spend to get the attention of someone at a distance of, let's say, a thousand light years. Who actually first came up with this thought that E.T. may have the same kinds of economic concerns we do, that maybe he would target these searches a little better?

I came up with the idea of thinking at it from a point of view of the guy who actually has to pay the bill for it. Because my experience is in the construction of high-power microwave devices, and I know what the rules of thumb are and how you optimize the cost, and it's all expressible mathematically in very simple ways. And so I employed that to say, well, if we were to build something, somebody wanted to see, and we wanted to broadcast 1,000 light years, 10,000 light years, what would it be like? And I was able to deduce most of its properties from simply following that line of argument. Then, of course, the argument was then turned around, and we said, well, suppose they care about cost, too. What should we be looking for? And what we discovered is that most of the searches that

have been done to date would not have seen what we ourselves would build. If you are correct about this, is it possible that we've already heard from ET, in other words, that the famous wow signal really was a wow signal? That's quite possible. The interesting thing about the WOW signal, which was so powerful, was that they had no signal detection electronics available, so they couldn't have seen a signal even if there was one in it. All they know is that they got a lot of power. Of course, when they noticed that on the printout, they went back and looked again, but apparently not nearly long enough. They didn't really stare at it the way that you've suggested. That's right. In fact, the total time devoted to it in the literature is like less than a day over the 33 years since it was first seen. Now, there may have been some people who've been looking and not reporting it. I don't know. But so far, there's not really been a systematic follow-up to it. And I should point out that there have been quite a few non-repeating signals seen

in the radio and astronomical in the sky, and they're consistent with signals from ET transmitters, but they haven't been seen again because we're not really staring and waiting for transients. It's always been picked up just by serendipity. Have you given any consideration to how long it would be prudent to, once an initial signal, a blip is received, how long we might stare at that? A month? A year? Ten years? We don't know how patient ET is. There's an argument that a year is a good number because for planets like ours at such and such a distance from our star, we know that planets rotate, so we know roughly what a day is. Therefore, looking at the whole plane of the galaxy for about a year steadily would, in some sense, falsify this simple picture of what a thrifty SETI beacon builder would do.

Unless they actually found something, in which case it would prove it. The point is, it's a falsifiable proposition, and SETI needs more of that. Something you can actually nail down and look for. And that's why we're trying to be very specific about what these beacons would be like. And it extends also, Jim, to maybe that we've been listening in the wrong band. That's true. The old waterhole argument that we should look at where the main lines are for water and hydroxyl, where the main lines are for water and hydroxyl, down around one and a half gigahertz,

I think is invalidated in part by our work, which shows that it's actually cheaper to build a beacon at higher frequencies because of the scaling of antennas. In fact, I would say five to ten gigahertz is a better range to look in than the one to two or three gigahertz, where almost all searches have been done. In fact, I think there, up until the last year or two, there haven't been any search. There's been only one search, the Phoenix search, that looked above 2.5 gigahertz. I first heard about this when I read Paul Davies' book, The Eerie Silence, but now I'm seeing just the phrase, Benford Beacons, popping up all over. What kind of reception have you gotten to the concept? Well, we've gotten more

reception. We've got more attention to these papers than any other thing we've ever done, and we have done hundreds of scientific efforts and papers. And I'll give you one clear example. I just looked at Google and Googled the phrase, Benford Beacons, in quotes, and I'll give you one clear example. I just looked at Google and Googled the phrase Benford Beacons in quotes, and I got over a million hits. That's Jim Benford. We'll hear more from him and his brother Greg when Planetary Radio continues in one minute. I'm Robert Picardo.

I traveled across the galaxy as the doctor in Star Trek Voyager. Then I joined the Planetary Society to become part of the real adventure of space exploration. The Society fights for missions that unveil the secrets of the solar system. It searches for other intelligences in the universe, and it built the first solar sail. It also shares the wonder through this radio show,

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Our nearly 100,000 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. Who better to tell us about Benford beacons than the Benfords themselves, or at least two of the three Benfords who came up with the concept. Gregory Benford has been on the physics faculty at UC Irvine for decades. Many of you know him better as the author of a shelf full of award-winning works of science fiction. His brother Jim is president of Microwave Sciences,

Incorporated. I asked Greg if the major SETI practitioners are enthusiastic about their challenging speculation regarding the search for extraterrestrial intelligence. I think generally they are. Frank Drake commented to us last year that when he first looked for a SETI signal 50 years ago, everyone thought there would probably be a SETI detection within a decade. That is by 1970. That optimism has gone away. Jim and I and Dominic are concerned that SETI may die from neglect when in fact it hasn't actually failed. It's simply not explored a large enough parameter space.

That would be a tragedy, wouldn't it? I think so because, let's put it this way. The Australians are now building a small array to look for transient sources, which is the key to what we are saying from our calculations, that these will be like a lighthouse going on and off, on and off, to attract your attention. That's far cheaper by orders of magnitude. The point is, if they use this array to look for lots of naturally occurring sources

but also find a SETI signal, for a few tens of millions of dollars, they will have made the biggest discovery in scientific history. That seems to me to be a good leverage. Let me go back to just maybe the nature of this signal, if we were to get it. I guess, really, by the way you're defining it, it would be very brief. What good would that do? I mean, what good would that do the aliens? They were just sending out one of these blips once a year.

Would that really be any kind of effective form of communication, or would it just be the start? The thinking here is that there are really, a beacon would have two major components. First, there's the attractor beacon, and that's what we're talking about. How do you get people's attention? And I suspect what one would do then is the same. Once you've got people looking at that piece of the sky with great sensitivity, they would find that either at a very close nearby frequency, or maybe even the same frequency,

either at a very close nearby frequency or maybe even the same frequency, at a very lower power level, it would be a broadband signal that had real message content. I'm not talking about Benford Beacons being a message, but being essentially a hail saying, we're here, look here, look here now. And once we saw it repeat, then we could take it much more seriously and start to stare at it and investigate. That would be an attractive way to do it. We would have an attractor beacon and then an information beacon. Almost as if you had to put up a bright, shiny object just to attract people to the spot, and then they maybe dug a little bit for the treasure. That's right. And the whole idea is you will beam this, if you're a beacon builder, into various pieces of the galaxy, and over the span of a year, you will have covered the whole

disk of the galaxy, which is about 10% of the sky. So we, looking in the sky, might see a bunch of fast pulses that go bip, bip, bip, bip, and do so for just maybe a second. Then, arguing that, after all, intelligent aliens will be on a planet something like ours, they'll know roughly a day and roughly a year. Maybe a day later, that bip, bip, bip reappears. That's how you establish a commonality of timing. And then a year later, the whole thing can happen again. You know, I'm glad you talked about looking through the galaxy, the plane of the galaxy,

because you also speculate as to where we should be looking. And I guess you're saying we ought to be looking toward the center. Yes, yes, definitely toward the center. That gives you the line of sight to the older stars in the galaxy, because star formation began at the center of the galaxy and moved outward. And also, you're cutting across the highest density of stars. The galactic center is around 26,000 light years away. It's a long way, but there's a lot in between us. Also, the radial symmetry of the galaxy implies that you really ought to be doing radial corridors of broadcasting

because that's the symmetry that everyone will know if they know any astronomy. So let's say we pick up that signal. We find the beacon and we discover that there's more going on close by. That signal is, particularly if we found it in the center of the galaxy, thousands and thousands of years old. Have you thought at all, even in the most speculative fashion, about what that might mean for us, and for that matter, for that civilization that originated it?

Well, first you ought to look at the motivations. I mean, why would anyone spend money to send a signal out that would be received perhaps thousands of years later? Well, we have our experience as humans. The longest-lived monuments in the world are almost all graves of years later. Well, we have our experience as humans. The longest live monuments in the world are almost all graves of various kinds. Look at the Cheops Pyramid, it's a grave site. So these long-term messages, I actually treat it in a book called Deep Time, and we know from the human experience that they tend to be things like brags, here we were and

we did all this great stuff, or examples of their best work, such as Statuary on the mausoleum of Mausoleus. Or Outright Pleased for Help, or perhaps even recruitment calls for a particular religion. They seem to last a long time, too. Those are all motivations that aliens might have. It's interesting to think about what might be in their messages. After all, you could just get their version of the Holy Bible. Absolutely fascinating. Gentlemen, we are out of time.

I'd love to pick this topic up again with you some other time. I congratulate you on the concept and also on its reception, and may it have deep influence over our search for extraterrestrial intelligence. Thanks again. Well, thank you. And could I add that if people want to see my talk at the SETI Institute, you can find it on YouTube. And we've got a link to that talk by Jim Benford, president of Microwave Sciences Incorporated,

on our show page at planetary.org, along with a link to an excellent article about Benford beacons in Astronomy Now Online. Jim was joined by his brother Gregory Benford, professor of physics at UC Irvine and a double winner of science fiction's Nebula, among other awards. By the way, Greg is working on a new novel with fellow hard science fiction writer Larry Niven. Up next is What's Up. Stay with us. It is time for What's Up with Bruce Betts, the Director of Projects for the Planetary Society. Welcome.

I love What's Up. You do. You're enthusiastic, and that's what we love about you, Matt. What's Up? Venus, still low in the west, looking really bright shortly after sunset. Jupiter, the star of the evening sky, high in the east in the early evening and looking quite stunning. Uranus, just a little over a degree away and might be able to pick it out in binoculars. Did you take your telescope out? You said you would. I did, but I had let the little battery in the finderscope die. And with that stupid little LED finder, if you don't have the little red dot, you are up a creek.

And so I was up a creek. So I did eventually find Jupiter sort of manually. Jupiter, it's that bright thing. You just line up the two. So check out that bright thing. Let us move on to this week in space history. Big week. 53 years ago. Dawn of the space age. Launch of Sputnik. A major anniversary. Sp anniversary spaceship one wins the x prize 2004 robert goddard born in 1882 i'm telling you it was just a party week neil's bore born you know because he was all right that's good enough let's move on to wait am i doing this

yeah you'll have to do it this week. We didn't get any additional entries, so if you would like to be heard, I mean, we don't care. You don't have to do anything fancy, but help us out. Send us your rendition of Random Space Fact. Just saying the three words as an MP3. Get fancy if you like.

You don't have to make Carl Sagan say it. If we use it, we'll send you a shirt. It's up to you, though, big guy. Random Specifact! Hopefully it comes out amusing. Anyway, Neptune. We don't talk a lot of Neptune. I felt badly for it. Neptune, 60 Earths could fit inside Neptune. Now, you know, for scale, Jupiter, there's that whole thousand Earths inside Jupiter. But Neptune's still not a baby planet. Yeah, it's big and it's pretty. It's nice blue. It's big and blue. Just like your microphone cover. It is, yes, as a matter of fact.

Approximately three and a half Earths could fit inside that. Yeah. Yeah, let's go on to trivia. We had a good trivia question for you. What was the prime recovery ship for Apollo 11 when it came back and splashed down in the Pacific Ocean? How'd we do? Carrie Conley of Elm City, North Carolina, is our winner this week. She said it was the USS Hornet, which had also served off the coast of Vietnam and was the recovery ship for Apollo 12. But the Hornet was the prime recovery vessel or ship that picked up those

guys who flew to the moon. Carrie, we are going to send you a Planetary Radio t-shirt. Be sure and tell us what size you want, folks. Sam Lipson, he volunteers on the Hornet. He actually still works on the Hornet, which is retired and sits in Alameda, California. Anybody can go up there and visit, and apparently it's got some cool stuff, including a Mars rover facsimile. Well, that's just very cool and very nice that he's volunteering and we heard from him. Now, you told us you were going to tell us some wonderful thing about your magical, mystical relationship with the USS Hornet. Indeed I did, and I wanted to bring it in and show it to you.

We could scan it, I suppose, put it somewhere on the website. But I couldn't find it in the box of memories in the garage. But here's the story. I was very excited about Apollo 11. I know I was probably the only one on the planet. And I was a little kid, but I was filming off of the television with my father's Super 8 camera. They came back to Earth, and of course they were covered by the Hornet. About a week later, we get in the mail a letter.

The letter had come from, and the postmark was from the USS Hornet, on the day Apollo 11 was recovered from the ocean. There was nothing inside the envelope. There was no return address. My father claimed he had no idea why I had received this. That's weird. That's very weird. There wasn't some type of cease and desist order?

Stop filming the TV coverage? No. cease and desist order stop stop filming the the tv coverage no sealed envelope to this and addressed to me dumb kid little kid in you know san pedro california with that canceled uh canceled postmark or can't whatever you call it but there was uss hornet on that day wow that's really cool you should find that in the box of memories. And I should find out if you were the person who sent that to me, would you let me know and I'll send you a shirt? And do they have to provide some kind of proof or are you just going to take everyone who says they sent it to you? I didn't really think it out that far. Let's give you another trivia contest that who knows what story you'll have about this one.

Let's give you another trivia contest that who knows what story you'll have about this one. What spacecraft that is scheduled to be launched in the next few weeks, actually a few months, let's say, appears to be named after a cookie? Go to planetary.org slash radio, find out how to enter. It's the Chips Ahoy! Ahoy! I got the macaroon I guess that's not a cookie you've got until the 11th of October

at 7pm no we better finish this we've got until October 11th I had that right Monday October 11 at 2pm pacific time which is 7am someplace to get us your answer to this one.

All right. Everybody go out there, look up in the night sky, and think about cookies. Thank you, and good night. Got milk? He's Bruce Betts, the Director of Projects for the Planetary Society. He joins us every week here for What's Up. Join us next time as we visit the annual meeting of the American Astronomical Society's Division for Planetary Sciences. Planetary Radio is produced by the Planetary Society in Pasadena, California,

and made possible in part by a grant from the Kenneth T. and Eileen L. Norris Foundation. Clear skies. Thank you.