Air Date: Week of January 28, 2005
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When the Huygens space probe landed on Titan, Saturn’s largest moon, on January 14th the world watched in awe. Living on Earth invited Neil deGrasse Tyson, the director of New York’s Hayden Planetarium, to talk about the mission. Tyson tells guest host Bruce Gellerman about Titan’s unusual features, what we didn’t learn from Huygen’s data, and why the government is shifting its priorities for space exploration.
GELLERMAN: From the Jennifer and Ted Stanley Studios in Somerville, Massachusetts, this is Living on Earth. I'm Bruce Gellerman, sitting in for Steve Curwood.
Talk about "Lord of the Rings." On January 14th, a nine foot tall, robotic space probe named Huygens, made a soft-landing on Titan, Saturn's largest moon. For a few hours, the instruments aboard Huygens collected data and images—the first ever of the surface of the mysterious cloud-shrouded moon…and what pictures they were! One scientist called the landing "one of the greatest achievements in the history of space exploration."
Joining me to put things in perspective is Neil deGrasse Tyson—an astrophysicist and director of New York's Hayden Planetarium. Dr. Tyson, welcome to Living on Earth.
TYSON: Hello, great to be back.
A Huygens Descent Imager/ Spectral Radiometer (DISR) instrument image shows two new features on the surface of Titan. A bright linear feature suggests an area where water ice may have been extruded onto the surface. Also visible are short, stubby dark channels that may have been formed by 'springs' of liquid methane rather than methane 'rain'. (Credit: ESA/NASA/JPL/University of Arizona)
GELLERMAN: I saw some of these images - the surface is very exotic.
TYSON: Yeah, it's one of the more exotic surfaces in the solar system. It's cold - about 300 degrees below zero Fahrenheit - and, you know, we say, okay, it's cold, so what? Well, there's certain gases that we've come to know and love here on Earth, like methane, which comes out of your stove if you live in big cities. That methane on Titan, it's so cold it has liquefied. And so, methane is abundant on Titan, and in a liquid state it's made lakes and rivers and tributaries. And so, one of the things that makes it odd is that it has these features that we normally associate with water, and it's cut by moving hydrocarbons.
GELLERMAN: If my high school biology serves me right, isn't methane a byproduct of metabolism? And doesn't that suggest life?
TYSON: You remembered almost all of it correctly. (LAUGHS) It's an organic substance; it's an organic molecule, and so, it's one of these fundamental ingredients that you'd find in any soup that contains life. On Titan, it's not alone among the molecules that we find there that we know are precursors to the formation of life. If we look at Earth before life formed it's got a lot of the same features--kind of spooky--a lot of the same features that we see on Titan. So, in fact, there are astrobiologists who see Titan as kind of a laboratory into Earth's past simply because of how rich it is in organic ingredients.
GELLERMAN: But there's no hope that it would ever evolve from a proto-Earth into something new?
TYSON: Well, we don't know. For example, life on Earth is the only life we know, and we're pretty sure life that we know requires water. But maybe other kinds of life, it doesn't necessarily require water but maybe it just requires a liquid of some kind. We know water is useful in the body to move nutrients from one part of your system to another. Maybe it's not the water that matters, but just a liquid.
So it's fun to speculate, at least from the science fiction angle, what kind of life could exist there today, using liquid methane as its mechanism by which you can move a circulatory system around in a creature.
But apart from that, as best we know on early Earth, it took a long time for life to get started - well, you wouldn't want to wait around that long. (LAUGHS) You know, a few hundred, a couple hundred million years. So, yeah, we wouldn't want to wait as long as it might have taken for life to start on Earth, to look around on Titan. So, what you do is look and try to use it to inform some uncertainties that remain in the early Earth.
GELLERMAN: What do you mean?
TYSON: In the early Earth we have some fossil records, we see some rocks, the evidence is just kind of fragmented - whereas here is a whole world just thriving with organic molecules. And so, that will help us pinpoint what might have been going on in the early Earth, even before life had formed.
GELLERMAN: I heard that they had volcanoes that were spewing ice?
TYSON: Yeah. We think of volcanoes as these places where hot lava comes out, but the physics of a volcano is not so much that things are hot but that what was once a solid turns to gas. And when you have gas it builds up pressures and it's got to release somehow, so it punches through the surface of the planet. So on Earth what punches through is hot gases, and lava spews forth. On Titan, you just need some heating to render the methane gaseous. There are other gases there, by the way. Ammonia is there, there might even be some alcohols, the kind of things that you find in your kitchen, or in the kitchen cabinet. These are common household ingredients, but if they get warmed up and turned to gas, it's going to punch through the surface of the moon and you can get what we call "ice volcanoes."
GELLERMAN: I heard that the space probe had six instruments, and one of them failed. It was by an experimenter in Idaho. It was supposed to measure wind velocity or something, but somebody didn't turn the instrument on.
TYSON: Yeah, well, these spacecraft and space probes, they have a certain amount of real estate on their surface. And what you do is you invite people to propose experiments that get attached to the various sides of the spacecraft. And one will measure, for example, magnetic field. One will measure wind velocity. There's a microphone on the probe that's measuring sound. There's another one that measures whether the craft was bobbing - because it might have landed in one of these lakes - and so the bob meter would tell you if that's in fact what it had done.
And so, yes, one of the experiments, they think there was an error traceable to a human error, but I think that remains to be fully analyzed in terms of the nature of that error. But it's not, I mean, it's a very big, complex spacecraft. You know, we keep thinking of human error as, "My gosh, there's human error!" Well, okay, when you're researching on the frontier there are human errors, and it's not…from a scientific point of view it's actually quite natural. And none of us, except the guy who's losing his data, is losing sleep over this fact. It's just a very natural phenomenon on the frontier of cosmic discovery.
GELLERMAN: Dr. Tyson, what didn't we learn from the space probe that landed on Saturn's moon?
TYSON: What didn't we learn? Well, first of all, it only landed in one spot. So, you know, it's a big moon. It's bigger than our moon. It's the second biggest moon in the entire solar system. One of six moons bigger than Pluto, by the way, and it's also bigger than Mercury. So, it's a big world out there. And, so, what didn't we learn? Well, the probe only had battery life for a couple of hours, so we weren't there long enough to see how things change. Does it rain methane? Does it snow methane? Does it, you know, what's the other side of the moon look like? You know, what at any moment is in the dark side? Over time, how much does the climate or the weather change? So, these long- time, baseline questions can't be answered by two hours' worth of data.
GELLERMAN: This probe hitched a ride on the Cassini spacecraft, which is, I guess, still up there?
TYSON: Yeah, yeah. In fact, the Cassini was the communication link back to Earth from the Huygens probe. So, when Huygens descended down it didn't have a big enough antenna to talk to Earth so it talked back up to Cassini, and Cassini then beamed back to us. But Cassini has its own trajectory around Saturn, and so one of the limits to how long Huygens could communicate with us was how long Cassini was in view and close enough to actually receive these signals and beam them back. And so, there was Huygens still giving us this faint signal even though Cassini had to drop off and pick up at the rest of its orbits around Saturn. But it's going to be making this big loop orbits around Saturn for the next several years which includes views from above. We never see Saturn from the top, and that'd be especially striking because that's where you see the ring system broadside. And that would be…I'm looking forward to that view.
GELLERMAN: Well, this experiment, this probe, was a very expensive gamble. What did it cost…1.3 billion dollars?
TYSON: No. Well, it's more than $3.2 billion, but it's spread over a dozen years or so. It's seven years to get out there, a few more years in orbit around Saturn. So, the real cost you have divide by the number of years, and you get a few hundred million dollars. Which, of course, sounds like a lot until you realize that that's, you know, Americans spend more on lip balm than the cost of this mission. So, you know, put it, keep it in context.
A Huygens Descent Imager/ Spectral Radiometer (DISR) instrument image of a dark plain area on Titan, seen during descent to the landing site, that indicates flow around bright 'islands'. The areas below and above the bright islands may be at different elevations. (Credit: ESA/NASA/JPL/University of Arizona)
GELLERMAN: Well, just recently there was a report that the Hubble space telescope, which has been up for about 14 years now, needed some repairs and that the Bush administration is going to be cutting the budget and not making those repairs. I know a lot of your scientific research was done with the Hubble space telescope…
TYSON: That's correct and still is - I'm on a data stream that's actively being obtained from the Hubble telescope as we speak. So, yes, that's a controversial decision because here's this perfectly fine working telescope, and it's ready to be serviced according to its natural schedule. But it gets serviced, of course, by the manned mission, the manned program services this unmanned telescope. And the new space vision for NASA leaves little room to go and repair the Hubble telescope. Because what it wants to do is go finish, use the shuttles to finish building the space station and then retire the shuttle and phase out our participation in the space station, so that the manned program can do something other than drive around the block. It's been going around in low-Earth orbit for the past 32 years. So, the controversy here is we know it's a great telescope, we know it's bringing back great data, but there's a whole other vision statement that NASA is in desperate need of. And it's the weighing of those two that is now the field of debate.
GELLERMAN: But you're part of that vision statement, you were -
TYSON: Yes, I was. I was appointed by Bush to serve on a commission to establish a trajectory for this vision statement going into the future - 10, 20, 30 years into the future. And it was dubbed the "Moon, Mars and Beyond" commission because the moon and Mars were targets in this effort.
GELLERMAN: "Moon, Mars and Beyond." So…Mars?
TYSON: Yeah, Mars, yeah, yeah! I mean, if you're going to spend 10 billion dollars out of the 15 billion dollar NASA budget on the manned program, do something other than go drive around the block - you know, boldly going where hundreds have gone before, which is low-Earth orbit. Go back to the moon, on to Mars, visit asteroids. You know, one of these asteroids has our name on it. It has our name on it just like it had our name on it 65 million years ago and took out the dinosaurs. Let's go up and get comfortable with these things and figure out how to deflect them out of harm's way. There's a lot of work to be done in the solar system that is not served by not leaving low-Earth orbit.
GELLERMAN: Dr. Tyson, does one of those spacesuits have your name on it?
TYSON: (LAUGHS) Well, there's an asteroid with my name on it, yeah, but it's not headed towards Earth. (LAUGHS)
GELLERMAN: No, would you like to go to Mars?
TYSON: Would I like to go to Mars? Um, I was never really intrigued by space travel even though I'm of the generation who was. I was, you know, I'd love to know what it's like to be weightless, I think that'd be kind of cool. I'd bring a little bag with me, you know, ‘cause I was never good on the amusement park rides (LAUGHS). But other than that, no. I mean, I'm intrigued and I'm excited by it, but there're people who would climb over others to get to that place. So, they - I'd let them do it.
GELLERMAN: Dr. Tyson, I want to thank you very much, it was a real pleasure.
TYSON: It's a pleasure to be here, thanks.
GELLERMAN: Dr. Neil deGrasse Tyson is an astrophysicist and director of New York's Hayden Planetarium. His latest book is called "Origins: Fourteen Billion Years of Cosmic Evolution."
[MUSIC: Gustav Holst "Saturn, The Bringer of Old Age" Royal Philharmonic Orchestra conducted by Andre Previn (Telarc) 1990]
GELLERMAN: Coming up: Where do you think the U.S. ranks among the world's nations when it comes to protecting the environment? To find out - keep listening to Living on Earth
[MUSIC: Paul Horn "Danca Das Cabecas (Head Dance)" The Altitude of the Sun (Black*Sun) 1989]
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