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Planetary News: Cassini-Huygens (2005)The Planetary Society's Huygens Weblog:Bringing you Huygens Mission Events As They Happen!By Emily LakdawallaJanuary 12-15, 2005 This blog is no longer being updated. For more up-to-date information you can read the latest Huygens news, visit our Cassini-Huygens and Titan pages, and look at the data returned from the Huygens probe. Thanks for reading! --ESL Jan 12, 2005 | 16:45 CET | 07:45 PST"It's going to be great!"In two days, it'll all be over; for better or worse, Huygens will have hit the ground on Titan, and back on Earth we'll be waiting to see whether the data will be returned. Today, I arrived at ESA's European Space Operations Centre (ESOC) in Darmstadt, Germany. I'd never been to ESOC before and was curious about how it would compare to the mission control areas I've been in at NASA's Jet Propulsion Laboratory. To my surprise, when I arrived at ESOC, Huygens Mission Operations Manager Claudio Sollazzo came to greet me at the guardhouse. Sollazzo is a gregarious but soft-spoken Italian in his fifties, who worked for ESA in Germany for nearly twenty years before coming to the U.S. in 2001 to coordinate Huygens and Cassini operations. He was clearly the man of the hour, I observed as we walked together; our conversation was interrupted every minute by well wishes, a handshake, or a thumbs-up from every passer-by. He glowed with every expression of hope and goodwill. "It's going to be great," he told me. But before it is great, there is an awful lot of work to be done to prepare for what is going to be ESA's biggest show ever. After we ate lunch I tagged along with Sollazzo to a media briefing given by Jocelyn Landau-Constantin, the head of ESA's communications office. Speaking about the number of media who plan to attend the descent, she said, "It's not only big, it's absolutely enormous!" There will be 220 members of the media present at ESOC--more than three times more, Sollazzo told me later, than there were for Mars Express' arrival at Mars. Landau-Constantin was clearly delighted with the forthcoming media attention, but it was a delight tinged with a hint of panic. ESOC is much smaller than your typical NASA center; as Sollazzo gave me a tour of the operational areas I was stunned at how few buildings there were to hold the operational staff for essentially all of ESA's missions. Huygens, Mars Express, Integral, Rosetta -- small but fully equipped operations centers were devoted to each one. There could be as many visitors as there are staff on site on Friday for the drama of Huygens' descent. By contrast, the science team members gathered for the meeting seemed to be happy and calm; they have little left to do before the data is returned, and appear to be eager for that long-awaited event to happen. At this point, there is nothing that anyone can do to affect the outcome of the mission; the point of no return came on December 24 when Sollazzo gave the order to the Cassini mission to separate Huygens from the orbiter. Now, everyone can only wait. Principal investigators like Marcello Fulchignoni, John Zarnecki, and Guy Israel blew off steam by ribbing each other. (Fulchignoni works on the Huygens Atmospheric Structure Instrument, whose acoustic data The Planetary Society will process to bring you the sounds of Titan); Zarnecki works on the Surface Science Package, which may or may not work at all after Huygens lands on whatever it lands on; and Israel works on the Aerosol Collector Pyrolyser instrument, which will be sniffing Titanian air.) The big topic of the media briefing was: when and how will the first images be seen? The images will be seen first by the members of the Descent Imager Spectral Radiometer (DISR) team in their own work area; but when that first image is put together, it will be carried to the Mission Control Room by Landau-Constantin and DISR Principal Investigator Marty Tomasko. The moment that the first image is flashed on the Control Room screens, it will be seen by the viewers around the world who are fortunate enough to be able to tune in to the ESA TV or NASA TV feed. This will certainly not happen before 8:30 in the evening, local time (7:30 p.m. GMT / 11:30 a.m. PST). But that first image will just be a postage stamp, one DISR frame. Because of the technical challenge of putting together 24 DISR frames captured by a spinning, falling spacecraft, it may be several days before we see the first DISR mosaic showing a full panoramic view around Huygens. Postage stamp or not, that first image will be really cool, and I'll post it here as soon as I get my hands on it. Jan 13, 2005 | 19:30 CET | 10:00 PST"This is probably not the best day to speculate."Anticipation here at the European Space Operations Centre (ESOC) is rising to a fever pitch. The full complement of more than a hundred scientists are here from all over Europe and the U.S.; they are running around, greeting each other, getting ready for the long-awaited data. At the same time, the media office is building stages, setting up lights, doing rehearsals, making last-minute changes... All in all it feels like tomorrow is going to be Huygens' wedding. Except that there are over a hundred 'parents' of this bride. In the middle of the preparatory madness they organized the taking of huge group photos of all the scientists and engineers around a model of the probe (wedding portraits?), and there's going to be a big banquet this evening for all of the visitors including VIPs from around Europe (the rehearsal dinner??). Perhaps I've stretched this simile too far, but the mood in the air really feels like the happiness, chaos, and stress right before a wedding. ESOC held their first press conference this afternoon, which didn't reveal anything particularly new to those of us who have been paying attention and anticipating this mission. Huygens will descend to Titan tomorrow morning, but we won't know what happened until much later. Mission Manager Claudio Sollazzo told us, "Huygens will enter the atmosphere about 10 in the morning but we will not hear anything until 5:15 and that will make us very very nervous." There were a few items in the media briefing that were news to me. One item: it is looking more and more like the best images from the surface of Titan will not come from Cassini's main cameras, but instead from the VIMS instrument, the Visual and Infrared Mapping Spectrometer, which can look through longer-wavelength "windows" in Titan's atmosphere. Another item that was news to me came from Marty Tomasko, the University of Arizona researcher who heads the Descent Imager Spectral Radiometer team (that's the main camera on Huygens). His last images are expected to come from about 150 meters off the ground. But, if Huygens survives the landing, DISR could still take pictures. What's cool about that is if Huygens lands in a liquid, it would be taking pictures through that liquid, seeing what's suspended in it. But I've been taking an informal poll of the science team to find out what they think they will land on, and no one has predicted liquid. The predictions range from "icy" to "squelchy" (the latter is how Surface Science Package investigator John Zarnecki described it ). After a few of these questions during the press briefing, Tomasko finally said, "This is probably not the best day to speculate. Probably you should save that question for 36 hours, and then we'll have a much better answer to give you." Jan 14, 2005 | 11:50 CET | 02:50 PSTTHE SIGNAL FROM HUYGENS HAS BEEN DETECTED BY THE GREEN BANK TELESCOPE!!! More in a moment... Jan 14, 2005 | 12:05 CET | 03:05 PST"We have heard the baby crying."It's amazing; it's wonderful; Huygens is alive. As Project Scientist Jean-Pierre Lebreton told us all just now, "It looks like we heard the baby crying. The probe is alive. We are on the parachute. We are very very pleased here I can tell you." How do we know Huygens is alive when she hasn't even finished her descent yet? After the fiery first few minutes of her descent, her first parachute popped open and pulled off her aft cover, and then the main parachute opened and the heat shield fell off. That's when she turned on her radio transmitter and broadcast a carrier signal. A carrier signal is a pure radio tone that contains no information beyond the basic and terribly important fact that Huygens is alive and that things have gone well, at least up until this point. It's like a baby's first cry. Huygens' signal is extremely faint. It has the power of a mobile telephone and it is falling through an atmosphere 1.4 billion kilometers (nearly a billion miles) from the Earth. This incredibly faint signal was picked up by the Green Bank radio telescope in West Virginia. If there was any ear on Earth that could have detected Huygens' faint signal, it would have been Green Bank, with its 7,854-square-meter (2.3-acre) collecting area. What does this detection mean? It carries no data at all, but it's fantastically important, because it gives all of Huygens' parents back here on Earth the assurance that Huygens is alive and well and has an excellent chance of being successful. We can all breathe one sigh of relief and uncross perhaps one set of fingers. To be able to be completely relieved and happy will have to wait until 17:15 local German time (10:15 am Pacific time), when the first sensible bits of data will be returned from Huygens by Cassini. Jan 14, 2005 | 15:15 CET | 06:05 PST"Congratulations, Mike Bird; you now have data."By now, it's all over. Huygens has hit the surface of Titan (John Zarnecki keeps talking about ESA requiring him to say that Huygens does not land, she impacts, so I won't say she landed!) Cassini is just about to turn toward Earth to relay the data. Once she turns and starts the data transfer, it will take 67 minutes at light speed for Cassini's signals to cross the 1.4 billion kilometers (870 million miles) to Earth, and forty-five minutes after that for the first Huygens bits to come down. That time, still in the future, could've been our first inkling of a Huygens success. But thanks to the Green Bank Telescope, we now know a lot more about how Huygens is doing--and it's all great news! They had another press conference here at 13:30 (that was 04:30 Pacific time), where they were able to add to the good news. Green Bank not only detected Huygens' signal, but they tracked it for two whole hours. That means that whatever was going on at Titan, Huygens stayed alive for at least two hours. (She's only guaranteed to last for about two and a half, so that was nearly the whole descent.) After two hours, Titan set from Green Bank's point of view. But--here's the next piece of great news--at about the same time Titan rose in Australian skies, and, in an event that no one dared to hope, the Parkes Observatory picked up Huygens' faint signal. Even as I write, Parkes is still listening to Huygens. What that means is that HUYGENS SURVIVED THE LANDING! (There, Dr. Zarnecki, since Huygens survived, I think you can now be free to call it a landing.) Here's what Jean-Pierre Lebreton, the Project Scientist, had to say about all of this: "What we know for sure is that we have had a successful entry, and we have deployed one, maybe two parachutes. Also we have got the Doppler signal from Green Bank telescope from 12:10. The probe has been transmitting for two hours. The signal has now been acquired in Australia--the telescope which was the subject of the movie The Dish was acquired at 13:30 local time. So we clearly have had an engineering success. Give us a few hours to give you a little of the data. We will work very hard tonight and tomorrow to tell you as much as we can tell." What all of this means is that Huygens is definitely an engineering success. In order for these signals to be detected from so far away for so long, all (or nearly all) of the complex engineering subsystems that were responsible for the entry and descent of the spacecraft must have worked. There is no science data yet--or nearly none. It is now known that one experiment has definitely worked. The Doppler Wind Experiment, unlike Huygens' other science instruments, has components on Huygens, Cassini, and on Earth. Scientists will study minute changes in the Doppler shift of Huygens' carrier signal as received by Cassini and the Earth to determine wind speed profiles. Lebreton reported that that experiment has worked. "Congratulations Mike Bird," he said to that experiment's principal investigator. "You now have data!" Jan 14, 2005 | 16:08 CET | 07:08 PST"The probe has now been transmitting for five hours."Project Scientist Jean-Pierre Lebreton now tells us that Huygens has continued to transmit for five hours, twice her promised lifetime. He says the scientists are waiting very patiently for their data. "They have waited seven years; they can wait a few more minutes." Jan 14, 2005 | 16:26 CET | 07:26 PST"We have PSA data."Cassini has begun to transmit data from the Huygens transmitters aboard the orbiter! The first forty minutes or so of data is housekeeping, and then the science data will arrive soon after that! And just after they made this announcement, they showed our Art Contest winner, Chelsey Tyler, on ESA TV, talking about her work. (Click here to see all the winning art.) Jan 14, 2005 | 17:39 CET | 08:39 PST"Huygens is a scientific success!"More in a moment... Jan 14, 2005 | 17:46 CET | 08:46 PST"We have got on the ground station data from more than two hours after the Huygens touchdown."The press conference that was scheduled for 17:15 was postponed for 15 minutes, and rumors of bad news began to circulate among the gathered press that the first packet of data contained nothing but zeroes. But within five minutes, the video from the Mission Control Room showed some sudden celebration. There was brief applause from the press gathered in the media center, but they didn't know what they were celebrating, so all became quiet again. The ESA representatives finally arrived, and everyone applauded -- but hushed quickly again, waiting for the news. Jocelyn Landau-Constantin, the Huygens press officer, was trying to keep her composure (trying hard not to grin!) as she began. She immediately gave the floor to Jean-Jacques Dordain, ESA's Director General. Dordain said: "The morning was good; the afternoon is better. We were an engineering success this morning, but we can say this afternoon that we are also a scientific success." He had to stop there because of the long applause and shouting from the audience! Dordain then said, "We are the first visitors of Titan, and scientific data that we are collecting now shall unveil the secrets of the new world. In fact we have got on the ground station data from Huygens long after the touchdown, more than two hours. I must say that we are short of ground stations! The [Huygens] batteries are much more solid than the number of ground stations which can receive the signal. "Cassini has just started to deliver the data collected by Huygens, and we night be able to see the results during the night." Jan 14, 2005 | 17:57 CET | 08:57 PST"There is frantic activity from radio astronomers around the world."Jean-Pierre Lebreton spoke at the press conference. "We are receiving the data on two channels. We have a question mark on one of the channels. But from the data we are receiving on Channel B, we can say that all of the instruments are nominal. We are not seeing any of the science data, we are only seeing what we call housekeeping data, so we can say the instruments have been switched on and are sequencing at the right pace. On Channel A we are still trying to understand what we are getting from the telemetry. "Other good news: the latest contact we've had from Australia was from 15:55 UTC [16:55 CET and 07:55 PST], the probe was still transmitting. There is frantic activity from radio astronomers around the world, moving west, trying to arrange data reception in Germany and possibly in Holland. We don't know whether we are going to see the probe dying. The orbiter is not listening to the probe anymore. So we are trying to get the radio telescopes activated as fast as possible, but those are big beasts to be moved. Let us hope they succeed." Jan 14, 2005 | 18:24 CET | 09:24 PST"This is only the beginning."David Southwood, Director of Science at ESA, says that the arrival of the Huygens science data means that the torch has been passed on to the science team from the engineering team. "This is only the beginning," he said. He meant that this was just the beginning of the results of the science mission--and he was also trying to tell us that the results of this mission just aren't going to be known for days, weeks, months, even years from now when, as Southwood said, "scientists will still be arguing about the data." But, when pushed, scientists can't help doing just a little bit of speculating. That's how they work. So here are a couple of little initial tidbits of speculative potential facts that they have mentioned. Number 1: Since the probe lasted for a really long time, it's "probably a good conclusion" that the probe landed on a solid, not a liquid surface, Lebreton said when he was pushed. Of course, that doesn't rule out John Zarnecki's "squelchy" surface prediction. Number 2: One thing that may have helped the probe last a long time was that it appeared to stay unexpectedly warm. At an elevation of only 50 kilometers (about 30 miles) above the surface, her interior was still at a balmy 25 C (77 F), despite the outside temperature being a frigid -180 C (-290 F). Lebreton wasn't ready to say what this might mean. It could be over-performance of the spacecraft, but it could also mean a wide variety of unexpected things about the atmosphere. For those of you who like instant results, I think you'll be disappointed on an answer to this question, because after all Huygens was a mission focused almost entirely on Titan's atmosphere, so it's going to take a very long time to synthesize scientific conclusions from all of this. Jan 14, 2005 | 18:51 CET | 09:51 PST"We have detected an impact."According to John Zarnecki, the Principal Investigator on the Surface Science Package, that instrument successfully detected an impact with the surface of Titan. He also said that the Huygens Atmospheric Structure Instrument (which is the same one that will be producing the sounds from Huygens) detected the same thing at the same time -- which means that both instruments probably got it right! Of course we know that Huygens did impact the surface, but it is always a happy thing to discover that your instruments work. He also said that it looks like the probe lasted about 147 minutes, which is 12 minutes longer than the predicted 135, but is "well within the error bars" of the predictions. However, he said this was still an early result--he didn't want to say for certain, because the members of a team had a bet on, and the number "looked suspiciously like the one I picked," Zarnecki said. Jan 14, 2005 | 21:00 CET | 12:00 PST"Drainage channels."We have now seen the first picture, and Marty Tomasko, the Principal Investigator for the Descent Imager Spectral Radiometer, remarked that the patterns of squiggly dark lines on a bright surface looked like "drainage channels" to him. It is certainly a complex surface that we saw! It was one of over 350 images Tomasko said they had, taken from an altitude of 60 kilometers (about 35 miles), which should be below the cloud deck. As soon as I get my hands on a digital version I'll post it here... Jan 14, 2005 | 21:45 CET | 12:45 PST"Rolling stones!"Here is the first image from Huygens! Little information has been published with this image, but it's safe to speculate that it was taken from the surface of Titan. In the foreground, we see rounded stones. Any geologist worth her salt thinks of one thing and one thing only when she sees round rocks: some river of some liquid has rolled broken chunks around, wearing down their edges, making rounded cobbles. Or, as United States Geological Survey geologist Larry Soderblom remarked to me: "We've got rolling stones!" Is that enough speculation for you?
Jan 14, 2005 | 21:51 CET | 12:51 PSTDrainage channels:Here is the image that looks like it has dark drainage channels on a light field. Amazing, absolutely amazing; we still don't know if there are liquids on Titan but I haven't yet heard another explanation for "dendritic" (or root-like) channels seen from up high and rounded rocks seen from near the surface. Who would have expected this? Still, we could be seeing something like on Mars, where there is abundant evidence for past liquids active on the surface, but no evidence for present liquids. Time will tell.
Jan 14, 2005 | 23:10 CET | 14:10 PSTWhat is that??This third image is awfully difficult to interpret. According to the ESA website, "It was taken at an altitude of 8 kilometers [5 miles] with a resolution of 20 meters [65 feet] per pixel. It shows what could be the landing site, with shorelines and boundaries between raised ground and flooded plains." I'll be really curious to see what they show us tomorrow. The next press conference is at 11:00 a.m. CET, 02:00 am PST tomorrow, January 15. This blogger is going to sign off to get some sleep now, but I expect that the science team will be working all night to see just how many of Titan's mysteries they can unravel in twelve hours.
Jan 15, 2005 | 10:35 CET | 01:35 PSTListen to the Sounds of Titan!The HASI-PWA team on Huygens has given The Planetary Society access to the data from their "microphone," so that we could make some "Sounds from Titan," with a little help from Society friend Greg Delory at Berkeley. Like the pictures I can't tell what they mean yet, but I think I can hear the whoosh of Huygens' descent! Jan 15, 2005 | 14:31 CET | 05:31 PST"It's impossible to resist the speculation."You might want to see all the new images I just posted... 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:
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. Jan 15, 2005 | 16:56 CET | 07:56 PST"A dance party to Titan."You can hear some weird techno sounds from Titan in a sound file that was made from the Huygens HASI RADAR altimeter instrument data. Marcello Fulchignoni had described these sounds as a "dance party to Titan" when he played them at the press conference this morning. The techno sounds alternate with something that sounds suspiciously like a heartbeat before the spacecraft achieves a "lock" on the signal reflected from the ground. A very tired Roland Trautner (a member of the HASI team) just gave me these sounds and explained them to me just before he went home to crash from yesterday's dizzying experience. It seems that everyone here at ESA's European Space Operations Centre has gone home--you can't stay up all night and suffer the highs and lows that everyone here, scientists, engineers, administrators, press officers, reporters, guests, and I went through without needing some time to recover. My Weblog will end here; I'll return to regular news coverage of the Cassini-Huygens mission from now on, updating you with the new images and new discoveries from the Saturn system as they are made. Congratulations to the Huygens scientists and engineers, ESA, and all the people of Europe and the rest of the Earth for their landing on the surface of an unexplored world. |
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