Planetary Radio: Space Exploration, Astronomy and Science - Galaxy Builder Andrew Benson

Episode Date: January 25, 2010

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A topic of galactic proportions, 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. Andrew Benson builds galaxies for a living. We'll visit his Caltech office to find out how and why. Emily Laktawalla builds excitement, this week focused on how you may be able to select a site on Mars to be imaged by the highest resolution camera circling the red planet. She'll be here in a second

or two. Bill Nye, the science and planetary guy, is at a spaceship factory with Planetary Society President Jim Bell and former President Neil deGrasse Tyson. And I'm in the freezing damp cold with Bruce Betts for this week's What's Up Report, including another chance to win a signed copy of William Hartman's Traveler's Guide to Mars. Emily, congratulations on your second article in Sky and Telescope, and I guess now people can see it online. That's right. I wrote an article in the January issue on amateur imaging,

amateurs downloading and processing digital space image data from unmanned spacecraft, and that article is now available for free for download from their website. So we'll put up the link to that blog entry where you also have an image, one of several, I guess, that was assembled from images snapped by Opportunity. It's quite a pretty picture of the Martian landscape. Yeah, that clouds over Mars picture always really arrests people because it's, you know, the dead landscape of Mars, the sort of frozen sand seas, and yet overhead, there are actually these clouds in motion across the sky. It's pretty cool.

Speaking of taking pictures of Mars, let's tell people how they can take their own, maybe, if they're very fortunate, with the best camera circling that planet. That's right. Well, I suppose some people might argue with you about the best, but it's certainly the highest resolution camera on the Red Planet. might argue with you about the best, but it's certainly the highest resolution camera around the red planet. And yeah, they have finally unveiled their website called HiWish, where you can pick a spot on Mars, give a science justification and explain why you would want to take a picture of that site. This is actually something that the high resolution imaging science

experiment promised to have from the outset. I'm not really sure why it's taken three years for it to get online, but I'm awfully glad it has. I've already submitted my four targets that I asked them to take pictures of. We'll have to wait and see how many of them actually get through the pipeline. Tell us about one or two of yours. Why did you choose them? One of them that I had to go back to was I have exactly one peer-reviewed paper to my credit. It was published before I was married, so it's under my maiden name, Stewart and Head, 2001, my credit. It was published before I was married, so it's under my maiden name, Stuart and Head, 2001, volcanoes in the Aeolus region on Mars. And so I wanted to go back and take a picture of one of the structures that we identified as a possible strata volcano in a very old area on Mars. The

others that I was looking at were just some cool-looking channel features. How does this work? I'm sure there's no charge, but how soon might the HiRISE team start telling people, yes, your selection is going to be imaged? Well, thanks to Google Mars, it's gotten a lot easier than it was back when this was first done with the Mars Global Surveyor camera, the mock camera. Now it's pretty easy. The website has a little image of a map of Mars from Google Mars that shows you exactly where there have already been pictures taken, not only by HiRISE, but also CTX, the context camera on Mars Reconnaissance Orbiter, and also by MOC on Mars Global Surveyor. So you can see which areas of Mars have already

been covered at high resolution and pick your target accordingly. You just click a spot on the map, it automatically spits out the latitude and longitude. You have to give a title to your image and write a brief justification for why you think this particular area of Mars would be interesting at the high-rise resolution of about 30 to 25 centimeters per pixel, and you have to pick a science theme. Then once your selection gets into the queue, it will take a minimum of two to three months before it could possibly come back from Mars. The suggestions get ranked, and then some of them get sent to the spacecraft, some of them get sent back into the queue for evaluation again.

So once a month, you get a chance. Maybe your picture might come back from Mars. All right, it doesn't get much more interactive or exciting than this. Thanks very much, Emily. We'll check in with you again next week. You're welcome, Matt. Emily Lakdawalla, the Science and technology coordinator for the Planetary Society, and she maintains the Planetary Society blog, and we'll have the links up to both of these pieces.

Now, let's hear from Bill Nye, who has a couple of special guests. I'll be right back with Andrew Benson of Caltech. Hey, hey, Bill Nye, the planetary guy here. This week, the board of the Planetary Society is at SpaceX. This is a rocket factory in Los Angeles where they are making rockets that will take us to the space station or beyond. And I'm here with Dr. Jim Bell and Dr. Neil deGrasse Tyson. And gentlemen, what do you think of SpaceX?

Oh my gosh, it is so cool. All these rocket toys in this place. It's like a giant factory for space nerds like us. And gentlemen, what do you think of SpaceX? Oh my gosh, it is so cool. All these rocket toys in this place. It's like a giant factory for space nerds like us. I think the CEO, Elon Musk, the billionaire who earned his wealth by writing the billing program now used by PayPal. That's how he made his first billion. I think he just never grew up. He's still a kid playing with toys.

So let me ask you this. Should we be concerned that the United States, for example, NASA, does not have a way to get back to the International Space Station? Hell yeah. In other words, Dr. Tyson, you're saying that a company like SpaceX is not capable of getting to the space station? No, I'm saying we should be. Oh, no. Oh, I thought you were worried that no one could go to the space station. I think whoever can get us there, the best and the cheapest, let's do it.

Save the money for other trips as well. A lot of destinations in the solar system. Absolutely. And when you think about retiring the shuttle and getting worried about, you know, how can we get back to the station, you look at a facility like this and these amazing rocket engines sitting here being built by a private company. I mean, total employee count, 850. Absolutely. We're going to get back there. We're going to get back there. And let me say, as an engineer, there's plumbing and nozzles and some control systems.

In many ways, it looks like any other rocket factory, but it's so lean and mean and elegant. It's exciting. Let's not be worried about it. Let's go to the stars. I've got to fly. Bill Nye the Planetary Guy. Awesome. It looks like an image taken by the Hubble Space Telescope of deep space, with scores of galaxies revealed.

It's not. It was generated by a computer model that has, for the first time, shown us how galaxies form and why they take the beautiful spiral and other shapes they do. Andrew Benson is a senior research fellow at the California Institute of Technology in Pasadena. He has been working with Nick Devereux at Embry-Riddle University and colleagues at the University of Durham in Britain. Their work will soon be published by the Royal Astronomical Society. Andrew, thank you for welcoming me first into a warm and dry office here on the Caltech campus. How long have you been in the business of building galaxies?

So I've been working on this kind of galaxy construction business since 1997, so getting close to 13 years now. This has become a much more sophisticated process, or I should say model, than I guess when you got started with all this. That's absolutely right. Yes. When we got started, things were much simpler. We had much less knowledge about the structure and properties of the universe. We didn't really know how much dark matter there was. We didn't know anything about dark energy at that point. And life was pretty simple.

And this, in some ways, for a theorist is quite good because it gives you a lot of room to speculate and try things out. But as time has gone on, there are fantastic telescopes out there, people doing a lot of work measuring the properties of the universe and of galaxies. And the data gets better and better. It gets more and more difficult to make your model match that data. And so you have to refine things, try and make it more realistic, basically do a better job. And so that's what we've spent the last 10 to 13 years working on. As I remember from my astronomy class in college, I was told that, yes, there are these different

types of galaxies, different shapes, configurations. And basically, we're not sure, but we think the ellipticals are just the old spirals, that when a spiral turns into a senior citizen, it becomes an elliptical. My impression from what I've read is that your research says not so much. That's right. So that basic idea has been around for quite a long time. There's some truth to it, but it's not the whole story. And what we've been trying to explore in our latest work is to ask the question, well,

what really drives one galaxy to become elliptical and one to become a spiral, for example? Obviously, it must be something different about the way in which they formed. But we really wanted to try and understand that in detail and see if our model could actually match what we see out there in the real universe. And this is a question that has puzzled astronomers and cosmologists for decades. I mean, it was Hubble who came up with this taxonomy of the different shapes of galaxies. And we'll try and put an image of that up on the website at planetary.org slash radio,

along with links to some of your sites. But I guess it's all these developments that you were talking about, the additional data and a much better understanding of dark energy and dark matter that has enabled you to come up with this. That's right. As you said, it's been around for getting close to 100 years now when Hubble was the first to really start to classify galaxies based on their shape. And, of course, if you ever look at an image from, say, the Hubble Space Telescope, an image of galaxies, their shapes are one of the first things that jump out at you.

Galaxies are either these very smooth ellipticals, or many of them are spirals like our own Milky Way, and some of them are kind of just messy looking and don't really fit into any category. So Hubble realized this and he classified them, and ever since people have been trained to explain what causes this dichotomy. Well, they had no hope of being able to explain this since they had no idea that there were these things, dark energy, dark matter, which apparently without building them into your model, your model just doesn't work. That's absolutely right. If we don't have dark matter in our model, there are no galaxies that form. If the universe consists just of normal matter, mostly hydrogen and helium gas, then what we find is that if you let the universe, our model universe, evolve for 13 to 14 billion years, all that you get is diffusely distributed gas floating around kind of smoothly in the universe.

There are no galaxies. There are no galaxies. That dark matter is crucial because it provides a gravitational pull that collects matter together and allows it to collapse and form these very dense systems that eventually turn into galaxies. How much dark matter are we talking about? Quite a lot. It turns out that something like 85% of the mass in the universe is dark matter. of the mass in the universe is dark matter. The regular matter, hydrogen, helium, carbon, everything else that we know about, makes up just that remaining 15% or so.

So the dark matter really is the dominant mass component of the universe. And yet we still have no idea what it is. No, we don't. And this is in some ways quite worrying. Of course, a lot of people are putting a lot of effort into trying to figure this out. There are dog matter detection experiments of various different types going on around the world. People are working very hard on that, probably because if they find dog matter, it's going to get them a Nobel Prize. But yes, we don't know. We think it's some kind of fundamental particle. There are many theories out there for what it could be, some more speculative than others, but we just don't know.

We have to wait for experimental verification of that. And yet, we know it's there because we see its influence everywhere, as you've said. No galaxies otherwise. And you built it into your model. Tell us a little bit about this model you call Galform. Tell us a little bit about this model you call Galform. Essentially, a computer software package which attempts to model the formation of galaxies in the universe beginning from just a few hundred thousand years after the Big Bang, so the very early stages of the universe. And it essentially tries to model the process of galaxy formation over the intervening 13 to 14 billion years of cosmic history.

And the way it does that is by combining various different bits of physics. So it includes things like the gravitational pull of dark matter. It accounts for other processes such as the rate at which gas can cool. That turns out to be very important in establishing how quickly galaxies can form. And quite crucially, especially for galaxy morphologies, it includes calculations of the frequency with which two galaxies might merge together. That's Caltech cosmologist Andrew Benson. More in a minute when Planetary Radio continues.

Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio. We put a lot of work into this show and all our other great Planetary Society projects. I've been a member since the disco era. Now I'm the Society's Vice President. And you may well ask, why do we go to all this trouble? Simple. We believe in the PB&J, the passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening. Of course, you can do more than just listen. You Transcription by CastingWords 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. We are visiting with Caltech cosmologist Andrew Benson. He has spent 13 years building and refining a computer model that has revealed how galaxies form and why they are found in shapes Edwin Hubble first categorized in the 1920s. How closely now does this model match up with what we see out in the universe?

So it now does a remarkably good job. At the present-day universe, so at redshift zero, we have a huge amount of data from measurements of galaxy luminosities to their sizes to their distribution through space, and the model is actually able to predict a lot of those things correctly, you know, to within 10% to 20% or so, which in this game is very good. What's even more remarkable is that having found a model which gets those things correct, we can ask what it predicts for further times in the past. So if we look back into space, we're looking back in time, and we can actually ask the model, well, what did galaxies look like at Redshift 1, say, six billion years after the Big Bang? And the predictions there actually also match up with the observed data pretty well. Of course, there are aspects where

it doesn't work so well. Details of things such as the gas content of galaxies, we know that it currently has problems getting right. We don't understand why, but that's something we're always looking into. The problems are the interesting aspects. We're always trying to figure out what is it that we've missed? What don't we understand? So the model, like the universe, continues to evolve. That's absolutely correct, yes.

I guess the reason that I find galaxy formation such an interesting area to work in is that our understanding is far from complete. So there's always lots of new things to learn. There are problems that arise, and then we have to think of what might we have gotten wrong here. Is there some crucial bit of physics that we're missing? So yes, these models continuously evolve in response to our better theoretical understanding and also in response to new data, which tell us new facts about the universe. Can you give us some kind of idea of how complex this model is? I mean, after all, you're modeling the universe.

That's right, yeah. It's quite a big project to undertake in many ways. The model is in some ways very simple and in other ways. The model is in some ways very simple and in other ways very complex. The simplicity is that it considers just a few aspects of galaxies such as the amount of dark matter in them, the properties of any spiral disk that they may have, the properties of any more spheroidal component to them which may look like an elliptical galaxy, and also things like black

holes that they may contain. So it's very simple. It treats galaxies as quite simple objects. The complexity arises because all of those different components of galaxies can interact in very complicated ways. And we can write down the equations that describe that in just a few lines. But the results of it are very complicated and take a lot of work to understand. Major league number crunching. Yeah, this is pretty big number crunching. What's nice about this technique is that we don't need world-class supercomputers. We don't need the really, really big computers that some cosmologists use for calculations. And that's nice because it makes these models then quite quick to actually compute and run.

Where do you do your computing? So we've recently started doing a lot of our sort of heavy-duty computing in the cloud. This is kind of new technology in many ways that is becoming a very established way of doing a lot of computing tasks, and academia is very interested in this, I think. So I was fortunate enough to get some time on Amazon's cloud computing infrastructure. And this is the Amazon we all know as the place we can go and buy books, and they have this cloud of computers out there waiting for folks like you to bring projects. That's right. of computers out there waiting for folks like you to bring projects.

That's right. Yeah, I mean, they have huge numbers of computers for handling their business. And a few years ago, they started making some of them available to essentially anybody who wants them for a price to do whatever calculations you want to do. And so a lot of other websites now use these. And Amazon actually provides some grants to the research community to get free access to these. I was fortunate enough to get one of those. And so this is quite amazing. I mean, I sit at my computer in my office, and I can fire off multiple copies of my model that go out to some computer in one of Amazon's warehouses, and it starts grinding through the

calculations. It could be running 100 copies of it simultaneously. And this allows us to do the calculations very rapidly. It's amazing. It does make me think, are you familiar with the Planetary Society's work on the SETI at Home project, which was one of these first uses of distributed computing like you're talking about? That's right. Yeah. I mean, in many ways, it was one of these first uses of distributed computing like you were talking about. That's right. Yeah. I mean, in many ways, it's kind of the same idea, although in a more commercial way, I guess. It's basically making use of computers that would otherwise be sitting there not doing anything. So instead, we can take up their CPUs and put them to work. Where do you go from here? As you said,

the model continues to evolve. What's the goal of the research? My primary goal right now is to look back to the very early stages of the universe. And I think that's going to be in the next 10 years or so where a lot of the interesting action is. We have new telescopes that are being built, 30-meter class telescopes, and the James Webb Space Telescope, which will sort of be the successor to Hubble, all of those are going to be able to

peer back to the very early stages of the universe and perhaps observe galaxies really in the process of just beginning to form. So what we'd like to do is to see if our understanding of galaxy formation is good enough to predict what those things are going to look like. I'm working very hard at the moment to try and predict what the universe will look like about a billion years after the Big Bang and slightly earlier. And then hopefully if we can do that in advance of these telescopes starting to observe the sky, we can actually make real predictions and test the theory. Very exciting stuff. Best of luck as you

continue this work, modeling this place where we and everything else lives, our universe. Thank you. Andrew Benson is a senior research fellow in theoretical cosmology. He is part of the TAPER group at Caltech, the Theoretical Astrophysics Including Relativity Group, a great name in itself. And he is one of the primary folks who've come up with this, the Galform model that is showing us with increasing accuracy how our universe and all of its billions and billions of galaxies containing their trillions of stars came to be.

We will check in on the local portion of that universe. That will be our regular weekly visit with Bruce Betts for this week's edition of What's Up, just a few seconds away. We're out back at a very chilly Planetary Society back office in a very damp Southern California. I'm freezing. That's why I have my Cosmos One windbreaker on here because it's really cold back here. I think it's punishment for us doing it outside last week and taunting everyone. You just kept saying, oh, it's so beautiful out here. Now it's like five days straight of torrential rains and mudslides.

We're banished out to the back office that isn't even heated. It's our fault. Mr. Scrooge, can we have another lump of coal? That's Bruce Betts you hear there. He's the director of projects for the Planetary Society. It must be time for What's Up. It is indeed, Matt. And for those who are properly dressed for the Planetary Society, it must be time for What's Up? It is indeed, Matt. And for those who are properly dressed for the cold,

Mars opposition. Now's the time. Now's the place. January 29th, Mars will be directly on the opposite side of the Earth from the Sun, hence the name opposition. This has various implications, such as, you know, it's closer,

so it's as bright as it's going to get for another 26 months. It is going to rise in the east right around sunset. So right about this time the sun is setting and set in the west right about the sun. The time the sun is rising because Mars is the opposite side from the sun. So go out and see it. It actually is as bright, roughly as bright as the brightest star now, but looking reddish in its color, reddish-yellowish. And on the 29th, funcally enough to use the technical term, it is right near a full moon.

So Mars won't actually be as good to look at as opposed to a few days before or after because of the scattered light. But in terms of inherent beauty and it's cool, it's perfect. They're both full at the same time. Wow. Both hanging out on that side of the earth. So I love Mars. Go play with it.

You can also check out Jupiter in the evening if it isn't raining for five days straight. You can look over in the west and see it as the brightest star-like object over in that direction. And Saturn rising in the late evening, high overhead in the pre-dawn. That's our planetary lineup. Great. We go on to this week in space history. Opportunity rover landed on Mars six years ago this week. Still successfully partying on, headed off on its long voyage.

John Callis, head mission dude. I'm going to be out there next week, so we should be hearing from him on the show very soon with another update on the rovers. I'm going to go out to JPL. Excellent. It was always good to check in with poor spirit, kind of stuck, opportunities still chugging along. We move on to random spec.

Must have been some effect of the cold there, I'm sure, but I won't speculate. Oh, gosh, please don't. Neutron stars. Heavy. You got it. But what's even weirder is how small they are. Yes. It's their density that's weird.

Collapse remnants of stars that are somewhat larger than the sun. They have to be larger, and then when they collapse, they turn into these weird things called neutron stars, of which there are innumerable random space facts that are fascinating. The one I'm giving you is that they are about 60,000 times smaller in diameter than the sun, despite the fact that their mass is about one and a half to two times larger than the sun. They the fact that they weigh about one and a half, or their mass is about one and a half to two times larger than the sun. Wow. They are seriously squished.

Neutronium. Cool stuff. Neutronium. Yeah, you know, there's Star Trek, so they talk about building stuff out of neutron star material. Heavy dude. Star Trek, what can I say? Trivia.

Trivia. Trivia. We asked you, what are the mirrors of the Chandra X-ray Observatory coated with? How'd we do, Matt? Oh, great response. I think people want that book, that Traveler's Guide to Mars, the signed copies. And we're going to give away another one in a couple of minutes here. By Bill Hartman.

Yeah. So tremendous response. First time winner picked up the prize this time around. Valerie Lemoine, or Lemoine, I guess. I'm going to stick with Lemoine, I think, from Stockton, California. Yeah, yeah, I grew up not that far from here. Yeah, pretty close. Anyway, Valerie said they are coated with iridium.

They are indeed. So your typical optical mirrors coated with aluminum. And did people give us any other weird information? typical optical mirrors coated with aluminum. And did people give us any other weird information? You know, we got several people who pointed out how incredibly smooth and clean these mirrors are. And by the way, they were built, apparently, or they were coated in Santa Rosa, California. Shout out to my brother, Stephen, who lives up there with his family.

I don't think he had anything to do with it. Thanks, Stephen. It's probably good they didn't let him anywhere near that polishing process, actually, now that I think of it. But if the surface of the earth were as smooth as the surface of these mirrors i love these aren't they great tell me the highest mountain would be two meters high oh random space fact i'm sorry because we should have saved that okay but here's a couple of people pointed out and i love this that basically the dinosaurs died so that we could have x-ray telescope science. It's Iridium, right?

A lot of it from, you know, KT. Iridium, one of the first signs that there was a major impact at that time because of the higher levels of Iridium and they're spread out in geologic settings at that geologic boundary. Yes. Huh. Well, cool. It worked out for us in other ways probably too.

The other thing was that somebody commented, and I can't remember the name, I apologize, that, you know, here this stuff came to Earth and now we're basically sending it back where it came from. Get out of here, you knucklehead. So Valerie's going to win the book. Let's give people another chance. To the forgotten planet. I just don't ask enough questions about it. So an easy question about the forgotten planet because, you know, people forget about it, except when they make nasty jokes. Uranus.

Oh, yeah, I forgot. Exactly. What is its orbital period in Earth years? Orbital period of Uranus. How long does it take to go around the sun? Go to planetary.org slash radio, find out how to enter. And you'll win yourself a William Hartman Traveler's Guide to Mars, signed by Bill himself. Cool. Got till February 1, 2010 to get us that answer. All right, everybody, go out there, look up at the night sky, and think about Vikings. Thank you, and good night. You know that you're not allowed to say Super Bowl, because then the NFL will sue you.

I didn't. Oops. He's Bruce Betts, the director of projects for the Planetary Society, and he joins us every week here for What's Up. Far in space. Planetary Radio is produced by the Planetary Society in Pasadena, California. Keep looking up. Thank you.