Planetary Radio: Space Exploration, Astronomy and Science - Observing Earth: Annmarie Eldering's Eye On Our Atmosphere

Episode Date: December 17, 2007

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Observing a Planet Called Earth, this week on Planetary Radio. Hi everyone, I'm Matt Kaplan. Welcome to Public Radio's travel show that takes you to the final frontier. And sometimes that final frontier is right here at home. Our guest is JPL scientist Anne-Marie Eldering, an expert on planetary atmospheres, and especially the one we breathe. You thought there was no sound in space? Think again as Emily Lakdawalla takes us to the edge of the solar system for this week's Q&A. And Bruce Betts will join me for a frigid look at the night sky,

along with a new space trivia contest. Just a few seconds for headlines. NASA now expects Space Shuttle Atlantis to launch on January 10th, partly so that the huge Space Shuttle team can fully enjoy the holidays. The American Space Agency also reports that the Epoxy mission, relying on the Deep Impact spacecraft, has been redirected to a different comet. The reason? The original target, Comet Boethon, has disappeared. The details are in Emily's December 14 blog entry at planetary.org. And here she is again. I'll be right back with Anne-Marie Eldering. Hi, I'm Emily Lakdawalla with questions and answers.

A listener asked, has the Genesis mission produced any results or did the crash contaminate the samples? Genesis was a space mission that planned to collect samples of particles from the solar wind and close them in a carefully cleaned and sterilized capsule and return them gently to Earth so that scientists could use the samples to analyze directly the composition of the Sun. Unfortunately, the sample return capsule's parachute failed to open, so when it returned to Earth in 2004, it crashed into a muddy plain. The sample capsule cracked open, and many of its delicate detectors were crumpled or shattered. Scientists were hopeful that they could salvage at least some samples from the wreckage, but it was a time-consuming process to extract and clean them.

And once they had the samples in hand, scientists also had to figure out whether the samples had been contaminated by Earth's atmosphere and the mud from the Utah crash site. Happily, I can tell you that the Genesis team has managed to get clean samples out of the capsule, and if you stay tuned to Planetary Radio, I'll tell you what they found. Did you know Earth is a planet, too? More spacecraft by far have studied our pale blue dot than anyplace else in the universe. One of them is the Aura satellite, with four instruments that examine the portion of our homeworld's life support system called the atmosphere. One of those instruments is called TESS. That's T-E-S.

The deputy principal investigator for TESS is Anne-Marie Eldering, who is also the deputy manager of the Earth Atmospheric Science section in the Jet Propulsion Lab's science division. Last week, she and thousands of other scientists were in San Francisco for the annual meeting of the American Geophysical Union. She took a quick break to tell us about how TESS is helping us understand the role ozone and other components play in pollution and climate change. Anne-Marie, thanks very much for joining us on Planetary Radio, and I guess the weather is nice up there in the Bay Area. Yeah, when we're not busy listening to

scientific presentations, we're enjoying some sunny weather here in San Francisco, yeah. And how is AGU going this year? Must be a really interesting get-together. It's always a very interesting meeting. It's near 10,000 scientists, and for our atmospheric chemistry, we're seeing a lot of utilization of our satellite measurements and some great talks about pollution all over the world. Someone told us a little bit about what they're seeing over China and how they're making sense of those measurements.

And Ramanathan from Scripps was talking about global aerosols and how they're impacting radiation balance on Earth. So those are pretty interesting talks that I heard. This is all core to your interests, isn't it? It is, indeed, absolutely. What we, of course, want to talk about in large part during this conversation is tests. And our audience has heard a lot about different tests. Well, actually, a couple. One on Mars, one circling Mars.

How similar is your instrument to this one there at the Red Planet? Well, I also stumbled across information about those instruments when we were doing some website development. And I think the area that we're very similar is in terms of the wavelength of radiation that we use. All of these tests, the EOS tests and the planetary tests, are using infrared radiation, so the kind you see with night vision goggles. But one thing that's different about our measurement is our spectral resolution, the finite amount of wavelengths we measure at any one time is really, really small.

If you use those kind of numbers, it's 0.06 wave numbers, and that's generally an order of magnitude better than most of the other, any other Earth-observing measurement that we have right now. And I guess we better say we're talking about the tropospheric emission spectrometer, which has been up circling the Earth now in a polar orbit on the Aura satellite for about three and a half years. That's correct, right. I don't know how much folks know about all the words you just used, but the one we like to focus on is tropospheric because we are very interested in the layer of air between the surface you walk on

and about the height of where airplanes fly because that's an important layer for human activity and that we often impact with our activities. But for something like ozone, we've only ever been able to measure the integrated amount from the surface to the top of the atmosphere. So the TESS instrument has, for the first time, differentiated the tropospheric ozone from all that other ozone above us.

And that's letting us do some new science we were never able to do before with these kind of measurements. And you have what is described as pretty good spatial resolution. Are you actually able to generate, in a sense, images of the presence of ozone and other elements in the atmosphere? We do if we bring together data over a period of time. In the usual measurement approach, we're looking at about 3,000 footprints on the Earth in any one day because to get that spectral resolution, we kind of had to give up spatial coverage. One measurement's only 5 by 8 kilometers, so it's pretty good resolution on a footprint, but there's only 3,000 footprints on the Earth each day.

So when we want to make a beautiful map or show you kind of the big picture, we'll take 8 or 16 days of data and bring that together to make an image and a picture of what's going on. Those time segments of 8 and 16 days, that has everything to do with this satellite. Absolutely. It's every 16 days we start repeating over the same locations of the measurement. So we want to use either that period of time or half that period of time so you have similar sampling in the averaging that you do. TESS is just one of four instruments on Aura, and they apparently work very much as a team. That is definitely the idea. We know that to answer interesting science questions, you usually need a number of ingredients to throw in

the pot. And what tests can provide is this vertical information, but it's not covering every footprint. And then there's instruments like OMI, the ozone monitoring instrument, that's a U.S. Dutch experiment. And they actually do full mapping, but with no vertical information. So we often look at their ozone measurements or their NO2, which is a chemical that's part of the suite that makes ozone, and their aerosol measurements. And combining that all together, we can get a fuller picture of what's going on. For example, there's massive fires over Siberia a couple of years ago,

and you'd see the carbon monoxide and the ozone and the aerosols all as they came from those fires and moved around the earth. And with the instruments all together, you can start to see how that's happening and where it's happening and how fast the chemistry is making a change. It's a great set. And then they have experiments like MLF, the microwave limb sounder, and they look sideways through the atmosphere. So they can see smaller concentrations, but they can never see down into the troposphere. But sometimes the stuff we're emitting down near the surface gets lifted up and then starts to move very rapidly at those high altitudes.

And with MLS, you see that as material comes up high into the atmosphere and starts to move swiftly. So again, you put their measurements together with something more tropospherically focused, and you get a full picture of the atmosphere. Perhaps the most amazing thing about all this to me, and this is true for these Earth-observing platforms as well as spacecraft we talk about very commonly on this show, is that we are able now to learn so much from a distance. Is this revolution, is that a fair word for this, a revolution brought about by remote sensing? Yes, definitely for weather observations.

It's so clear what an impact these remote sensing measurements had because we knew a lot about what was happening near land surfaces where we could launch balloons, but there was still a great part of the Earth, 70% of the Earth is covered with oceans, and we're not getting good measurements over there. So once you had a satellite, it really filled in the picture. And the same is true with chemistry. There's infrequent fawns and aircraft, and you get a picture here and there of what's happening. But now when we have global observations, you start to put together a picture

of stuff you just had a hint of, and now you really start to see more fully. Another example is over Africa and South America as part of the land clearing and the crop clearing, they burn a lot of material over the year. And where does all that emissions go? Where does the smoke go? What happens to the chemicals that get emitted? And a lot of it gets moved out over the Atlantic Ocean and some of it towards the Pacific. And with these remote sensing measurements, you start to see the seasonal behavior of that, the spatial extent that gets what gets impacted, and to see from year to year what changes occur. So we're really, it's true. I would think it's fair to say there's some aspects of our atmospheric

chemistry understanding we really are making huge leaps forward with these kind of measurements. We'll hear more from atmospheric scientist Anne-Marie Eldreen after a break. This is Planetary Radio. 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.

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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're talking with Anne-Marie Eldring, Deputy Principal Investigator for the TESS instrument on Aura, the Earth-observing satellite that is helping us understand our own atmosphere. Before we get into exploring some of those leaps forward, explain a term for us that you've used a couple of times, aerosols.

Aerosols. So aerosols are minute particles that float around in the air, generally less than 10 microns in size. And if you're an LA-bound person, you kind of recognize that as part of the smog that reduces how far you can see. Yeah, sadly. Yeah. And if you've looked at some satellite images, you often see the smoke plumes. Those are aerosols. Many different materials can make up aerosols, like smoke, sea salt.

You have compounds that come out of industrial emissions, and they'll make small particles. All that stuff is grouped up. And dust is another source. All that is what I mean when I say the word aerosol. Tell us a little bit about what your data is telling us about the atmosphere of our little planet. All right. So some of the exciting results that we're actually going to talk about here at the meeting this week, one of them is unraveling the budget of ozone.

So we know now through our new observations, as well as the aircraft and FON data, that there's ozone at about 10 kilometers of five miles above our head. And if you look at the U.S. as a whole, there tends to be more ozone over the southeast than other parts of the U.S. at that elevation. So we're trying to understand why that is. Where is it coming from? Does it come from the west? Does it come from the surface? Does it come from the stratosphere and move down?

Does it get made right there? And with our observations and some models of the winds and the transport, we're starting to understand that a lot of that ozone gets made because there's other chemicals that are sitting around and caught in the winds, and then lightning adds NOx or NO2, and the chemistry happens right there. So it's formed in situ, and then some of it tends to move off the east coast and head out over the Atlantic Ocean. So we had seen a hint of this from some FON data, which was collected over a short period of time, just one month. And now with the test data, we're starting to look at this

over the whole season of the summer and over many years and put together that kind of a picture of the terms and how much comes from the different sources. So that's been one interesting result. And then another one is just looking at pollution over some of the bigger cities. We had done work over Houston because they're very interested in understanding their local air pollution and how much might come from distant sources. And so we made sets of measurements over Houston and are working with their air quality team to understand the story there. But we've also been working with colleagues air quality team to understand the story there. But we've also been working with colleagues who are interested in Beijing,

and Beijing is doing some great experiments where they turn off large sources, like they cut down on traffic or they turn off their power plants. And they want to see what could they do to help make sure the air quality is really good for the Summer Olympics. I was just going to say, I bet you'll be watching during the Olympics next summer. Oh, yeah, and it's very interesting to see right now. You can see some of the very polluted days in the summertime over Beijing in our measurements, and we're interested to help them quantify the impact when they turn off these sources and how it changes the air pollution.

Have you been able to add to our growing body of knowledge about climate change? Actually, we have done some new research recently on that topic. And again, because TESS is able to differentiate the amount of ozone in the stratosphere from the part of the ozone in the troposphere, we can also look at the greenhouse gas effect of tropospheric ozone. A little primer on ozone, it has many different roles, and many folks are familiar with stratospheric ozone and ozone holes that happen over the poles. And that's one of the good things ozone does is in the stratosphere, it protects us from the UV radiation. But then when ozone is in the troposphere, up at the top of the troposphere, it actually the top of the troposphere,

it actually traps heat just like carbon dioxide and other greenhouse gases. And then when you think of the troposphere down at one kilometer right at our heads, it can be harmful to humans. So it plays good roles and less good roles in the atmosphere at different altitudes. So it's one of the greenhouse gases. different altitudes. So it's one of the greenhouse gases, and up to this time, only numbers we have have come from model predictions of how much radiation does that ozone hold onto and how much does it add to the heating. And from tests, we can now get an estimate of how much radiation it's holding onto from the actual observations. And our new results are showing that the upper

tropospheric ozone seems to capture about a third of a watt per square meter. That's what the estimate was from the models, and our data confirms that. It's between a third and a half of a watt per square meter based on observation. So it's a good way to make sure the model predictions are in line, And we can also see some latitudinal and seasonal information that we couldn't get out of predictions. Can you put that third of a watt in perspective, for example? Do you know the comparable figure for CO2? The CO2 number, I'm just going to make sure I really get this one right. You've got your reference works there? Well, actually, I have that little figure that's kind of part of my computer all the time.

Sure. The CO2 number is on the order of close to 2 watts per meter squared. Okay, but a third's still quite a significant percentage of that. It's a significant secondary gas. The CO2 wins over everything else, but then there's three or four pieces that are of similar magnitude, and tropospheric ozone is one of those. We're just about out of time. Can you add to the reassurance we've gotten recently that the worldwide ban on CFCs is doing good things for us up in the stratosphere? Oh, that's a good question. You know what? We haven't actually

looked at that question too deeply. We're going to have to give you the number of one of our colleagues on MLS who are the experts on the ozone hole and its recovery. Well, we'll look forward to talking to that colleague. And I'm sure you're looking forward to talking to some of those thousands of other colleagues. The AGU is not over yet. It is not. I still have two and a half more days of fun ahead. Well, have a wonderful time, and thank you very much for providing us with this update.

As we begin on this show to show how working in space is helping us to learn more about our own planet as well as others in the solar system and beyond. Thanks for the opportunity to talk with you today, Matt. You bet. It's really been a pleasure. Anne-Marie Eldrain is the Deputy Principal Investigator for the test instrument on NASA's Aura satellite. She's also the Deputy Manager of the Earth Atmospheric Science Section in JPL's, that's the Jet Propulsion Lab, of course, but you knew that, JPL's Science Division.

We're going to check in with Bruce Betts, another scientist who happens to join us every week for this week's edition of What's Up. That'll be right after this return visit by Emily. I'm Emily Lakdawalla, back with Q&A. Despite the unfortunate crash landing of the Genesis sample return capsule, scientists have managed to salvage some of the precious samples that Genesis collected from the Sun. Genesis flew in space with sample collectors exposed to the solar wind, the stream of charged particles that flows out of the Sun in every direction.

One of the main questions motivating the Genesis mission is, can the composition of the solar wind tell us anything about the composition of the giant cloud of dust and gas from which the sun and all the planets formed? To address that question, scientists looked at the composition of the solar wind during periods of ordinary solar activity and also during periods when the sun was experiencing the violent eruption of a coronal mass ejection. If the composition of the solar wind differed from quiet to active periods, then it would be difficult to figure out how to extrapolate the composition of the solar wind back to the time nearly 5 billion years ago when the solar system was first forming. Happily, the Genesis team found no compositional differences in the solar wind at different times,

so now they can use their samples from the sun to figure out the list of ingredients from which everything in the solar system was made. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Time for What's Up with Bruce Betts, the Director of Projects for the Planetary Society. We are out back at the Planetary Society in Studio 1A, which is absolutely freezing. It is colder than space here today. Colder than space?

Yeah, at least. It is cold. In space, no one can hear you shiver. But I can hear you shiver today. Yeah, there seems to be some heater issue in lovely Southern California. Really, man? Life support is in big danger here. Yeah, some law of thermodynamics has been violated to get this room this cold.

Seriously. I know it's been in the 30s and 40s at night here, but still. And almost on cue, the refrigerator turns on. So people have to hear that in the background now. So anyway, maybe it'll put out a little bit of heat for us. That's true. I just started. I've got a fire going.

That's good. That's good. Speaking of fires going, Mars. Mars've got a fire going. That's good. That's good. Speaking of fires going, Mars. Mars, now is the time. Go see Mars. Mars rising around sunset, setting around sunrise, rising in the east. It is the reddish, orangish, bright thing that's over there in the east in the evening sky.

It is as bright as the brightest star in the sky sirius which by the way in the late evening i found is a nice little comparison you've got reddish mars and bluish sirius they're they're a fair amount apart but if you look far to the right of mars you'll see the that bright thing is serious and uh mars at opposition on december 24th so on the other side of the Earth from the sun. It's actually because of elliptical orbits and how they play together. It's actually a little closer to Earth about a week earlier, but very similar. Looking cool.

It's in Gemini. You can also check out below it Castor and Pollux, the bright stars of Gemini, which are much dimmer than Mars. Closest than it will be again for 10,000 years. Yes. It's exactly wrong. 10 years. Yeah. Okay.,000 years. Yes, it's exactly wrong. 10 years. Yeah. Okay.

About 10 years. No, we always have those glorious emails you refer to that go around the internet, usually predicting August, which is what it was in 2003 when it really was closer than it had been in tens of thousands of years, but only by a little bit. Late in the next decade, it will be back to being almost as bright as it was in 2003. I'm going to hold you to that. Okay, you do that. You can also check out in the pre-dawn sky, Venus looking extremely bright in the east.

It's the brightest star-like object over there. If you look high above in the pre-dawn, you can see Saturn looking a little bit yellowish and like a bright star, but not way totally bright like these others were talking about. Comet Holmes, I went out and looked a couple nights ago. Still there, really tough as naked eye. Certainly not naked eye from Southern California. But with binoculars, you can still see it as the characteristic fuzzy blob, quite distinct in Perseus above our friend the star Murphak.

On to this week in space history. 1903, of course, first powered flight. 1968, Apollo 8 launched, first trip around the moon for humans. And 1999, the Earth-observing Terra spacecraft was launched. Good week. And Terra, which is sort of a sister spacecraft to Aura, which we are talking about this week. Indeed. Indeed.

Terra up there many years now already. Eight years. On to Random Space Fact! Oh, gosh. That was operatic. Oh, I thank you. Luciano, eat your heart out. He probably may mention it in news, or he may not have.

But I want to point out, I failed to mention it right when it happened. December 7th, a day that will live in infamy, but also a day where Uranus changed season. It was the Uranian equinox. Oh, yeah, yeah, yeah, right. And this only happens once every 42 years. So the North Pole of Uranus has been in the dark for 42 years and now gets to see a little sunshine and see it for the next 42 years. Kind of another random space fact part.

Because of the way the Earth orbit, the Uranian orbit, mostly the Earth orbit, plays with the Uranus orbit, there are actually three ring plane crossings, of which we have had several of them, two of them, and have one more coming up where we look edge on at the rings of Uranus. We've talked about it on this show. All the time around. Indeed.

This very program. Indeed. This very program. That means it must be true. As long as it's not coming from us. Exactly. We had real guests and everything. Speaking of coming from us, we have a trivia contest.

We do. We have a trivia contest. We asked you, who had the longest gap between space flights? And it was hard to keep Matt from blurting this one out. How did we do? Go ahead. Blurt it out now. So many people said, I don't even have to look this one up.

And yet there were a good number of people who got it wrong. People who said it was Leonid K. Kadynyuk. And it really wasn't because it was John Glenn. Of course, John Glenn with one of those first space flights and then coming back in the shuttle just a few years ago. 36, actually going on 37 years between February 1962 and October of 1998 when he got to go up on the space shuttle. Pretty cool. Impressive. I hear they're scheduling him for the first moon landing around 2020.

I wouldn't be surprised. He's a good choice. Nancy Atkinson of Rochester, Illinois. I'm glad she won. She always says the nicest things about us. She just wants to take this opportunity to say that Planetary Radio is dreamy. Oh, dreamy. That's us.

That's us. It was dreamy, not nightmarish, right? Yeah, that's right. Because she says, quote from John Glenn apparently, he said, you know, old folks can have dreams too, as well as young folks, and then work toward them. And to have a dream like this come true for me is just a terrific experience. Wow, that's nice. It seems like a good ending, but it's not because we have another trivia contest.

Sure enough. So someone else can get dreamy. Of course, I guess they do it just listening. But back to Mars, and it's coming close. How big, in the wonderful unit of arc seconds, how big will Mars appear from Earth at closest approach this year, 2007? How big to the nearest arc second? And if you, you know, recreationally you can compare to other years,

we'll certainly do that in a couple weeks. So you got until Christmas Eve, Monday, the 24th of December at 2 p.m. to get us that answer. How do they enter? Go to planetary.org slash radio. Find out how to send us your entry. That's it, isn't it? We took that out of order and it totally threw me off. There's nothing left to do except

get out of here to someplace warm. Indeed. All right, everybody. Go out there. Look up in the night sky and think about someplace warm. I. All right, everybody, go out there, look up in the night sky, and think about someplace warm. I know we are. Thank you, and good night. He's dreaming of chestnuts roasting on an open fire.

He's Bruce Betts, the director of projects for the Planetary Society, and he joins us every week here for What's Up? And this week wishes us a happy holiday. January 7, 2008, that's when Bill Nye the Science Guy will join the Planetary Radio Menagerie with the first of his weekly commentaries. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week. Thank you.