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Webcast Transcript

0:00:11

JOSH CHAMOT: Good afternoon. I'm Josh Chamot. Welcome to the National Science Foundation. Astronomers using the 8-meter telescope at the NSF-supported Gemini-North Observatory have captured the first images of storms of the topics of Titan, Saturn's largest moon. They followed observations from NASA's IRTF indicating increased cloud cover on Titan. The findings shed light on our understanding of Titan's atmosphere and help explain how seemingly liquid-carved terrain can exist in what scientists have thought was an arid region of the moon. Today I'm joined by Henry Roe of Lowell Observatory and Mike Brown of Caltech who, along with lead author Emily Schaller of the University of Hawaii at Honolulu and Tapio Schneider, also of Caltech, will publish their findings in this Thursday's issue of the journal Nature.

We'll go ahead and open our phone lines for questions now. Please note that the information discussed today is embargoed and cannot be released to the public until 1:00 p.m. Eastern Time on Wednesday. To ask a question of Henry or Mike, it's easy. Just at any point during the broadcast, just press *1 on your touchtone phone and you'll be placed into a queue, or you can always email questions to webcast@nsf.gov. While asking questions via telephone, though, be sure to turn down your computer speakers. There's a delay between the phone line and the webcast. And finally, note that the webcast is being recorded. We will ultimately post that to our website, www.nsf.gov, but if you wish to have copy of it, I can send you an audio file immediately after this.

So, first off, Henry, what did you guys see?

0:01:45

HENRY ROE: So, we've been using several different telescopes on the ground to study Titan's weather as often as possible over the last few years and with one of these telescopes, the 3-meter NASA IRTF, we've been watching Titan almost every night for several years. And for about two years, things have been pretty calm on Titan. Very few clouds, very little activity until April 13th last year and our IRTF program showed that something big was starting to happen. We brought in the Gemini 8-meter telescope on the next day, April 14th, and on almost every night for about a month and a half or two following that and saw an enormous event occur that kicked off cloud activity all over the Southern Hemisphere. This was interesting for several reasons. One of, it was about the largest event we'd seen for many years and it also showed how cloud activity in one area of the planet can kick off activity anywhere else in the same hemisphere, including over areas that are usually thought of as arid and dry.

JOSH CHAMOT: So, the images that you've caught, they rival the resolution of space stage telescopes. What's changed in the ground-based world? What are we expecting in the future and I guess either one of you can answer that.

MIKE BROWN: Let me jump in on this one. One of the reasons that this study was so powerful is because from the ground, we can take beautifully detailed images of Titan and see where the storms are and see where they're moving across the surface and the reason we can do that, and we couldn't do that even just a few years ago, is because of this new technique of adaptive optics that exists on telescopes where the adaptive optics corrects for the effects of the blurring in the Earth's atmosphere and you take this otherwise very blurry shimmery image and you switch on the switch to your adaptive optics and suddenly you get this nice, clean picture. These nice, clean pictures of Titan that we get are the best pictures that you can get from the vicinity of the Earth, including from space. So, we're better than anything else except for things that happen to be flying right there around Titan which have a little bit of an unfair advantage.

JOSH CHAMOT: And mentioning the ones that are flying around Titan, why are we looking at Titan with telescopes from Earth if there is a spacecraft that's flying around it all the time?

0:04:02

HENRY ROE: Well, because Cassini spacecraft returns much higher resolution images than we get but it only flies by Titan every few weeks or every month or so, and so it's like it gets snapshot every now and then on Titan, but we can look at Titan almost every night from the ground. This event that we saw back in April and May of 2008, Cassini didn't actually have a fly-by until the very end of the event and missed almost the entire event. So, the power of ground-based observing is that we can observe almost every night and, in fact, by using telescopes in different locations, going into the future, we'll be able to observe even every night on the Earth even when it's cloudy at one location on Earth.

JOSH CHAMOT: Very cool.

MIKE BROWN: It was really interesting to look at the Cassini data that had come from the same event. It came near the very end of this whole month-long series of storms that we had seen and you could tell from the very detailed Cassini data that there was something funny that had happened, but it was just little splotchy clouds spread everywhere and so they had no idea that it had been the end of this month-long series of events. The interesting thing about it is how this whole series of events unfolded over the equator, which really shows you where clouds can move to and with just a snapshot, it's a little hard to tell what's happening.

JOSH CHAMOT: Great. I'm going to take a second here to remind everybody listening – we've had some new reporters join in – that if you want to ask a question, all you do is press *1 on your touchtone phone and you'll be placed into a queue and then we'll bring you right into the discussion. If you're listening on webcast and want to send an email question, just send the question to webcast@nsf.gov. OK. Great.

One other question along those lines, getting to the basics, why is Titan of such great interest to astronomers?

0:05:51

HENRY ROE: Titan is an amazing place. Almost every process that you see occurring on Titan in terms of cloud formation or in terms of streams on the surface has an analog here on Earth but it's with alien materials. Of course on Earth, our clouds are made of water. On Titan, it's far too cold for water to be liquid and be in the clouds. Water acts like a rock on the surface of Titan. But instead, on Titan, conditions are just right for methane to be a liquid and flow on the surface or form clouds in the atmosphere. So you have a whole weather system based on methane and Titan. Just an analogy to the water-based weather system here on Earth. And similarly, you have seasons on Titan just like you have seasons on Earth and for much the same reasons. Titan's rotation is tilted over a few more degrees than Earth and its year is 30 Earth years long, so you're seeing slow seasonal evolution of this methane weather.

JOSH CHAMOT: Very cool. And it looks like now we have a question from David Perlman, who's on the line. If we can go ahead and connect him into the call. David?

DAVID PERLMAN: Yeah, thanks [Inaudible] late and I just need to know who the two guys are talking. One's different voice is different from the other.

JOSH CHAMOT: Sure.

DAVID PERLMAN: At the moment. I have other questions.

JOSH CHAMOT: OK. Well, let me go ahead and introduce them again. On camera, we have Henry Roe from Lowell Observatory and by telephone, we have Mike Brown from Caltech.

DAVID PERLMAN: OK. Thanks.

JOSH CHAMOT: Sure. And did you have questions you wanted to ask now your want to ask later?

DAVID PERLMAN: I emailed you one.

JOSH CHAMOT: OK. It may not have come through yet. Do you want to go ahead and bring it up?

DAVID PERLMAN: Yeah. Well, I could just tell you – I was trying to find out whether – to what extent the atmosphere that you've discovered, you've determined is different in any way from the atmosphere as perceived during the Huygens landing back whenever that was. I've forgotten.

0:07:56

MIKE BROWN: Couple years ago. Yeah. It's an interesting question and it's one of the sort of fascinating things about this study. From the Huygens landing, and Huygens landed very close to the equator and it looked very much like the atmosphere was dry and sort of desert-like and couldn't support rain or clouds and, yet, from that landing, if you looked around at the terrain, you saw these things that looked just like beautiful stream-carved valleys and almost shorelines, and so people have been scratching their heads for a long time about how to put those two observations together. We think that this is an important part of the story, which is that a storm somewhere else, that one of these storms like we saw occurred in a different place can cause clouds and rain at many different locations around the planet. So, even though these very desert-looking regions seem to be dry, seem to not be capable of having storms, they can be driven from other places around the planet.

JOSH CHAMOT: Great. One of the things I was going to ask again is about the observations that you've seen. They must be raising new questions. So, in some ways, they answer some questions and in other ways they're raising new ones. What is this bring to mind as far as where to go next?

0:09:21

HENRY ROE: Well, one of the biggest questions in my mind is how frequently do these types of large events occur? We have record of three of them over the past decade and a half. The first one in 1995 we have only a little bit of data on, but it appeared to be a similar size magnitude of event. Another one in 2004 that we covered quite well with Gemini observations and a few other telescope observations. And now this one. There are hints that they occur more frequently and so we continue to want to observe as often as possible and bring in other telescopes where that makes sense.

MIKE BROWN: It's interesting. This study, we really focused on the aftermath of this, essentially, atmospheric explosion. This explosion happened just at the very southern part of the Tropics and this atmospheric explosion sends waves and clouds throughout the Southern Hemisphere, but we don't talk very much about what causes this atmospheric explosion, and the reason we don't talk much about it is because we're not sure. We are suspicious that there's something happening in this one particular spot on the surface of Titan, but we don't know what. And so we’re going to be carefully watching all around Titan to see if there are any special locations where these strange sorts of things seem to happen and then see if we can try to figure out what's going on there.

JOSH CHAMOT: Great. And we now have another question via telephone. Let me just remind everybody again. If you want to ask a question, all you do is press *1 on your touchtone phone, and if you'd like to email one, send the question to webcast@nsf.gov.

We have Rachel Courtland from New Scientist on the line, and Rachel, when you get connected, go ahead and ask your questions.

RACHEL COURTLAND: Great. Thanks. You mentioned that there have been two previous episodes. Have those been seen in the same area, and I was also wondering if you could describe a little bit more what physically is going on that causes this atmospheric event to spread and whether there are any Earth analogs.

0:11:29

HENRY ROE: Well, the 1995 event, we have only very sketchy data on. This was before the era of adaptive optics that Mike was talking about, and we really don't have a good idea of exactly where that occurred. The 2004 event we covered in rather good detail and it was not in exactly the same location as this event. We don't really know yet. As Mike was saying, we don't really know yet what is causing these events. We can rule certain things out just from the fact that we've seen several of them in this time period. But we have suspicions. We think that it is likely tied to something going on on the surface, some type of geologic activity and Cassini has been returning evidence that Titan's surface is geologically active, but nobody's yet really found the smoking geyser or the new mountain range forming to say what that activity is yet, and that's one of the key things over the next few years and watching, looking for more of these events and trying to pin down exactly where they initiated from and using Cassini data to look at those points on the surface.

MIKE BROWN: And to be fair, one of the other authors on the paper, Tapio Schneider, here at Caltech thinks that you can have these sorts of atmospheric outbursts simply caused by the atmosphere itself and no need for something going on on the surface. So, there's still a lot of uncertainty about what causes these and this is why if we see more of them and if we see exactly, as you asked, if we see them repeating in the same places, it will become pretty clear. Back in that one that Henry talked about in 2004, we saw a lot of repeating activity in one spot and it was pretty clear something was going on there. We haven't seen anything else in this spot, but I'd be willing to bet that if we keep staring, which we will, we'll see something else happening right around there.

JOSH CHAMOT: So are you guys – go ahead.

0:13:23

HENRY ROE: I want to emphasize that it's really at this point, in terms of our understanding of what's causing the start of this event, initiating it, we really are just at the suspicions level and absolutely it could be atmospheric, it could be surface, and that what we really need to do is observe multiple more of these events to be able to distinguish between the different possible scenarios that are out there.

MIKE BROWN: You know, we didn’t answer the question. The other question was what exactly caused all the clouds to spread everywhere, and if there's an analog process on the Earth, and absolutely there is. Henry and I were joking at the start of this that we would never actually use the phrase "Rossby wave." But here I go. They're called Rossby waves, or planetary waves, that move in the atmosphere and they are big – you can essentially think of them as if this were going on in the ocean and you had some big explosion in the ocean, you would have this big waves going across the ocean, but these are now atmospheric waves. They behave a little bit differently on Titan because Titan rotates so slowly. On the Earth's Coriolis effect from the rotation causes these waves to bend and move, but here on Titan, they propagate even better so the fact that you have this explosion here can cause these waves all the way around and these clouds everywhere.

HENRY ROE: And those waves can form the clouds that are latitudes from where the initial formation was and we also saw a neat thing where we think what happened was the wave circled around Titan and came back to the original cloud and boosted it up about two weeks later after the original event. It re-strengthened the cloud when the wave had circled around the moon.

JOSH CHAMOT: Let me step back and ask you guys to go a little bit more into the adaptive optics 'cause adaptive optics are not new, but these observations clearly represent sort of a next level and it's exciting for those of us who are looking through ground-based telescopes because it brings a lot of capability to all these scopes that are here on the ground. What exactly was done? Is this something new that was done on Gemini or is this something being done all over, and how do the adaptive optics work?

0:15:31

MIKE BROWN: Let me give my spin on this one because – I think the – adaptive optics, as we said, is no longer a new technique on telescopes. It's been almost a decade where we've been able to do this where we see something through the blurry atmosphere and we use a very fast mirror to correct what the effects of the atmosphere and come up with a nice, crisp picture and this has been going increasingly well over the past decade, and the most amazing thing, to me, and Henry's been leading the Gemini effort here and so I get to sort of watch on the side as it happens, and so I get to sort of watch in amazement, which is that adaptive optics works so well these days that it's almost routine is that we can get these observations when we know something's happening. We can get these observations now, night after night after night after night after night because the Gemini telescope can say, "OK. We'll do a few minutes of adaptive optics. Get these images for these guys and then we'll go on and do something else," because it's no longer this special technique that requires a team of 15 people to get it all to work. It's just yet another tool in the astronomer's bag that can be used routinely at telescopes like Gemini. So, it's an amazing change in the way astronomy can work these days.

HENRY ROE: That's right. I think, actually, our first adaptive optics images of Titan that I took were 10 years ago this fall, and those images we would have you know, a whole night on the telescope and we would spend hours getting set up and tweaking and then you'd have a few minutes of everything working and you'd get your image. And nowadays, it's about 15 minutes of telescope time at Gemini. So, it's quite possible to ask for only a few hours of time over the course of six months and split it up into little chunks and get observations on many nights, and that's been a huge development. That’s part of the reason we're at Gemini, there certainly are other large telescopes out there with adaptive optics, but Gemini is unique in being queue scheduled such that we can ask for 10 or 15 minutes of time on many, many nights. You simply can't do that on the other big telescopes.

JOSH CHAMOT: Do you have any added capabilities on the other scopes that now that you've got the adaptive optics that there are things that you're hoping to see that you just hadn't been able to see before. Either one of you.

MIKE BROWN: I'm sorry. I didn't quite understand that.

JOSH CHAMOT: Now that you have these adaptive optics capabilities and they're performing well, do you have other scopes that you're hoping to tune towards other areas of the sky to see things that you had not been able to see before? Regardless about the time that you're now able to devote, are there capabilities that are now open to you that weren't before?

0:18:11

MIKE BROWN: So, adaptive optics is now capable of being used for almost anything in astronomy and the biggest new development in adaptive optics, of course, is not just the ability to correct anything in the Earth's atmosphere, but it's the ability to send a laser up into the top of the atmosphere, watch that laser and as that laser light comes back down, take that pulsating laser light and turn into the little spot and correct anywhere. So, in addition to studying things like Titan, we've been using these laser adaptive optics to look at things like satellites of tiny little Kuiper Belt objects out in the outer part of the solar system, where if you look at them with normal telescopes, you see just one little dot. Suddenly, you flip the laser on and turn the switch and that one little dot turns into two, or in our case, three little dots that you see circling around the object. So, in the solar system, it's been tremendously useful, and astronomers from the solar system out to the edge of the universe have been doing similar sorts of things.

JOSH CHAMOT: Great. And Henry, do you have anything you wanted to add to that?

HENRY ROE: No. Adaptive optics, it’s really become, like Mike was saying, a tool in our kit. You no longer have to be an adaptive optics specialist in order to use adaptive optics. It's just like another camera at most telescopes these days.

JOSH CHAMOT: Great. OK. I don't know that we have any other question so I'm going to ask one final one in a second. I'll remind anybody on the line that if you do wish to ask a question, just press *1 and be placed into the queue, or you can send a question to webcast@nsf.gov.

But in case we don't have others, just we'll close with this, and that is what are hoping to see next on Titan? If you're going to focus there, what are you looking for? What's the next focus?

0:20:02

HENRY ROE: Well, we're certainly going to continue to watch Titan. So far, we've only been observing Titan for a relatively short fraction of its year, just one season or so. Titan's year is 30 Earth years long and we've been observing for the equivalent of January, February, and part of March so there's an awful lot for us to still learn as we continue to observe Titan over the following coming years. We're going to continue to use multiple telescopes. The IRTF is a very important part of our repertoire, as is Gemini, as are some small telescopes that we're bringing online, and what we're going to be looking for is to understand how the seasons evolve on Titan. Where do the clouds form as we move into the next season, and continue to look for these large events and distinguish the different scenarios by which they may be forming.

JOSH CHAMOT: Great. Mike, did you want to add anything to that?

MIKE BROWN: I'm very excited about what Henry said on this very last part, is it's not just for understanding the seasonal evolution, which is a great – Titan is a place that's like the Earth and not like the Earth and we have very few of those. In fact, we only have one other of those in the solar system, and so with Titan uniquely, we get to be able to study something like the Earth that has seasons, that has a hydrological cycle and so trying to understand more how this goes is fantastic and I am extremely excited to see if we can't figure out why these large explosions of methane seem to be coming from what it looks like from the surface of Titan, though it may not be. But I want to see if we can track those down so I think that the future on Titan is quite exciting with the combination of large ground-based telescopes and including the Cassini spacecraft going around there. We have a lot still more to learn and I think that's going to be fun for the next few years, too.

JOSH CHAMOT: Excellent. We do have one other question from David Perlman – I'm sorry. Do you want to jump in there, Henry?

0:21:56

HENRY ROE: Sure. I'll just say, in many ways, as Mike was saying there, Titan is the most similar object to Earth. Not in the materials there, but in the processes in that what we see going on in it's atmosphere and surface are more similar to Earth than any other planet in our solar system, and like this big event we saw a year ago, every time we start thinking we sort of understand what's going on on Titan right now, that you know for the last couple of years, everything has been sort of predictable, it throws us a curveball and surprises us and that's a lot of fun that way.

JOSH CHAMOT: Excellent. Great. We do have another question on the line. David Perlman's back. David, can you hear us?

DAVID PERLMAN: Yes, sir, I can hear you and this is a question for Mike. Mike, you mentioned that you're using adaptive optics to look at satellites of some of the Kuiper Belt objects, are you training some telescope, whether it's Gemini or some other, on the objects like Sedna that you were reporting quite a while ago?

0:22:53

MIKE BROWN: Yeah, absolutely. So, Sedna, sadly, turns out not to have any moons, which is really too bad, but we have, with adaptive optics, both thought at that Gemini at the Tech observatory, we've been observing the satellites of Haumea. This was the one that was formerly known as Santa, formerly known as 2003 EL61, has two satellites around it and in very much the same way, to study a system that has two satellites so its satellites are changing so quickly and interacting so quickly, we were having a very difficult time figuring out what they were doing and the thing that finally allowed us to get a handle on how they’re working, it was, again, this sort of observations from Gemini Observatory where you can take 20 minutes today, 20 minutes tomorrow and 20 minutes the next day and finally start to watch these things over a significant period of time. We've also been observing Dysnomia, the satellite around Eris and so it's been a great ability to be able to do these things from these nice telescopes here on the ground.

DAVID PERLMAN: Thanks.

JOSH CHAMOT: Thanks, David. I'm going to go ahead and, seeing that we have no further questions, I'm going to go ahead and remind everybody that this is all embargoed. It will be available for you if you need to use it to file your stories right after the call and I'll give you some information to get that in a second, but this is all embargoed until Wednesday at 1:00 p.m. Eastern Daylight Time. Right now, though, I'll just go ahead and thank our guests for joining us today, Henry Roe from Lowell Observatory and Mike Brown from Caltech. We'll be in touch with you guys throughout the week. If any of the reporters on the line wish to get in touch with them one-on-one, we can make that very easily done. There is more information out there in the form of press releases. There's one from Gemini, one from Lowell, one from Caltech, one from Hawaii and we'll actually have one out there shortly as well. For contact information for all four of the study P.I.s and the media officers, if you want to get somebody on the ground to go knock on doors and to get visuals and other materials, just give me a call anytime at 703-292-7730, or you can reach me by email at jchamot@nsf.gov. And then I also want to remind everybody that there's another webcast here tomorrow at 1:00. It is also embargoed and it is also in regards to this upcoming Nature issue. This one is about increasing hurricane activity. In short, the Atlantic hurricane activity in the past 10 years has been as strong or stronger than at any time in the past 1,500 years apparently and warming ocean temperatures may be the reason why. You'll just come right back to this website. Your password will be winds, W-I-N-D-S, and the username, which will appear first, that's going to be "webcast." Both lowercase. And that's all. So, again, hopefully we’ll see you tomorrow, and thank you for joining us.

0:25:52.5

 

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