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Headshot of Emily Lakdawalla

Huygens landing day live blog

Posted by Emily Lakdawalla

14-01-2005 16:10 CST

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

Jan 14, 2005 | 11:50 CET | 02:50 PST

THE 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.

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?
First image from Titan's surface
First image from Titan's surface
Credit: ESA / NASA / JPL / University of Arizona

Jan 14, 2005 | 21:51 CET | 12:51 PST: Drainage 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.
Second image from Huygens
Second image from Huygens
Credit: ESA / NASA / JPL / University of Arizona

Jan 14, 2005 | 23:10 CET | 14:10 PST: What 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.
Third image from Huygens
Third image from Huygens
Credit: ESA / NASA / JPL / University of Arizona

 
See other posts from January 2005

 

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

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