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Headshot of Emily Lakdawalla

Huygens blog: "It's impossible to resist the speculation."

Posted by Emily Lakdawalla

15-01-2005 7:31 CST

Topics: Huygens, Titan, mission status, Saturn's moons

After a mere twelve hours of work, all six of the science teams on Huygens were able to report results this morning. You could easily tell the difference between the administrators and the scientists on this morning's press panel: the administrators looked bright, fresh, and well-rested, while the scientists looked decidedly weary. One, HASI instrument leader Marcello Fulchignoni, even admitted to a questioning reporter that he had not heard the question because he had nodded off.

Here's a few factoids from today's conference. Let me get the bad news over with first. There was some glitch somewhere--some mistake made, into which there will be a formal ESA inquiry--that resulted in the complete loss of one of two "channels" on which Huygens was sending data to Cassini. These were supposed to be two fully redundant systems, but a couple of the experiments depended on both channels working, in particular the Doppler Wind Experiment. This experiment relied on the Doppler shift of the carrier signal being transmitted from Huygens to Cassini and also to the Earth to reconstruct a vertical wind profile of Titan's thick atmosphere. The Cassini component of this experiment was lost because, apparently, Cassini just wasn't listening.

Fortunately for the Doppler Wind Experiment, though, radio telescopes all over Earth were listening, and even more fortunately, they were able to hear Huygens' signal loud and clear. So although they lost the data set they wanted, they will be able to recover their investigation's goals by using the radio telescope data. It will take "an enormous amount of work," ESA Science Director David Southwood told us, but "scientists love work. That's what they live for." (I'm sure that the DWE team would say, though, that they could have done with a little less work, thank you.)

OK, enough bad news, on to the good. John Zarnecki, of the Surface Science Package, who is always a crowd favorite, reported that they collected 3 hours and 37 minutes of data, of which 1 hour and 10 minutes was on the surface, and that the instruments work "brilliantly." He said the time of the landing was pinpointed at 8869.7598 seconds after T zero, that is, 2 hours, 27 minutes, 50 seconds after their clock started (which was a couple of minutes after they reached the interface altitude. He also confirmed (he was embarrassed to say) that the betting pool among the SSP team to guess the descent time was won by him (he was right within 7 seconds). The prize, a bottle of "Scottish medicine," was consumed by the team at 2:30 in the morning. Since we'd seen team members drinking champagne earlier in the evening, this added a whole 'nother dimension to the weary appearance of the panel.

Zarnecki's instrument has a "penetrometer," essentially a spring-loaded stick pointing out the bottom of the probe, which was designed to poke into the surface and measure how much resistance it met to try to figure out what the surface might be made of. The results? The stick went in 15 centimeters (6 inches), experiencing more resistance right at the beginning than later. Zarnecki tried to explain the force of the resistance that the penetrometer met. "The closest analogs I can give you are wet sand are clay, those are materials which would give a similar mechanical consistency." But he also added that another member of his team likened the surface to "creme brulee," with a thick crust and goopy interior.

After Zarnecki, Guy Israel confirmed that his instrument worked--the ports opened and closed and pumped properly--and then Marcello Fulchignoni came on. He was evidently dead on his legs but rallied himself to talk about his instrument, and when he played the sounds that came from the acoustic sensor and radar sounder, he conducted them like a maestro from his seat. We've got most of those sounds on our website now! But we don't yet have the radar sounds. When Fulchignoni announced to the world that you could get the sounds off our website, I had to jump out of my seat to start tracking them down. I'll have them for you soon, I hope; I've talked with members of the HASI team and if they can stay awake long enough they hope to have them available soon.

Because I jumped up from my seat at that point I missed what Sushil Atreya said about the Gas Chromatograph Mass Spectrometer results about the composition of the atmosphere. What everyone is most interested in there is the "mixing ratio" of methane--that is, the abundance of methane in the atmosphere--because it's methane that most strongly controls Titan's temperature and the amount of light that reaches the surface.

Finally, at long last, Marty Tomasko was able to show his pictures. We all oohed and aahed and applauded at the panorama he put together:

Huygens DISR panorama of Titan's surface

ESA / NASA / University of Arizona

Huygens DISR panorama of Titan's surface
This 360-degree panorama from the Huygens spacecraft, hand-assembled from a number of Descent Imager Spectral Radiometer (DISR) images, was taken at a distance of 8 kilometers (5 miles) above the surface of Titan at a resolution of about 20 meters (about 65 feet) per pixel. The left-hand side, behind Huygens, shows a boundary between light and dark areas. The white streaks seen near this boundary could be ground 'fog,' as they were not immediately visible from higher altitudes.

As the probe descended, it drifted over a plateau (center of image) and was heading towards its landing site in a dark area (right). From the drift of the probe, the wind speed has been estimated at around 6-7 kilometers (about 4 miles) per hour.

During the press conference, he remarked that the images were "absolutely raw" and so you had to be careful about interpreting them, but he went on to say "It's impossible to resist the speculation that we are seeing drainage channels or some part of a shoreline."

I overheard Tomasko being interviewed by the BBC later, and he remarked about how Earth-like the images seemed. That really struck me, because there are two places in the solar system whose surfaces we can't see because they are shrouded by clouds, Venus and Titan. Venus is always called our sister planet because of its similar size and distance from the Sun, but it's a fiery hell of volcanoes and desiccated plains with sulfuric acid clouds choking a thick carbon dioxide atmosphere. As for Titan--with Cassini's first views it seemed as though we were going to see the opposite extreme, a frigid hell, of ice volcanoes and choking methane clouds. Instead, we're seeing such an Earth-like place, with plateaus, basins, river channels and deltas. It seems so much more benign than it did before, possibly even beautiful by Earth standards.

Things are now winding down here; that was the last formal press conference. But I am still in Darmstadt for a few more days, and will see what more news I can dig up.

See other posts from January 2005


Or read more blog entries about: Huygens, Titan, mission status, Saturn's moons


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