The Green Bank radio telescope in West Virginia has picked up the Huygens carrier signal, which should have been activated after the opening of the main chute and the dropping of the heat shield. The signal carries no data other than this: Huygens made it through the entry into Titan's atmosphere. We should have data available by 1310 EST, routed from Huygens through Cassini. From an ESA press release: What the Green Bank radio telescope has detected is only a 'carrier' signal. It indicates that the back cover of Huygens must have been ejected, the main parachute must have been deployed and that the probe has begun to transmit, in other words, the probe is 'alive'. This, however, still does not mean that any data have been acquired, nor that they have been received by Cassini. The carrier signal is sent continuously throughout the descent and as such does not contain any scientific data. It is similar to the tone signal heard in a telephone handset once the latter is picked up. Says...

The Planetary Society's Emily Lakdawalla is covering Huygens events from Darmstadt here. From her latest post: 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...

Via the NASA TV site. Note the 2:45 PM slot, offering the first images from Titan (all times are EST). January 14, Friday 3 a.m. - 3:30 a.m. - Live Coverage and Commentary "Cassini Turns Towards Titan - Interruption of Radio Contact" - JPL/ESA 5 a.m. - 6:30 a.m. - Live Coverage and Commentary "The Huygens Probe Enters the Atmosphere of Titan" - JPL/ESA 6:30 a.m. - 7 a.m. - JPL Commentary - JPL (Mission Coverage) 7:30 a.m. - 8 a.m. - ESA News Briefing "Mission Status" - JPL/ESA 8:30 a.m. - 9:15 a.m. - ESA Commentary on Huygens Probe Mission - JPL/ESA (Mission Coverage) 9:30 a.m. - 10 a.m. - JPL Commentary - JPL (Mission Coverage) 10 a.m. - 10:30 a.m. - ESA Commentary "Cassini Turns Back to Earth - Data Transmission Begins" - JPL/ESA 10:30 a.m. - 11:15 a.m. - JPL Commentary - JPL (Mission Coverage) 11:15 a.m. - 12 p.m. - Huygens Probe News Briefing - JPL/ESA (Mission Coverage) 1 p.m. - NASA Update with Sean O'Keefe - KSC 2:45 - 3:15 p.m. - ESA Commentary "Presentation of First 18...

The Jet Propulsion Laboratory has posted a Huygens arrival schedule showing 4:51 AM EST as the time when Huygens powers up its transmitters. Pilot chute deployment now estimated at 5:16 AM EST, and surface touchdown at 7:34 AM EST. Also available at this page are multimedia files of Huygens arriving and a tracking animation. Image: An artist's conception of hydrocarbon pools, icy and rocky terrain on the surface of Saturn's largest moon Titan. Image by Steven Hobbs (Brisbane, Queensland, Australia).

The European Space Agency offers an outstanding animation showing the stages of Huygens' descent to Titan's surface tomorrow. Also available is an animation of the view from Cassini during the Huygens' descent. Some interesting facts about the event: Huygens' atmospheric entry angle is a whopping 65° at a velocity of six kilometers per second, with touchdown planned for the daylight side in the southern hemisphere. The probe will pull 14g during deceleration. The thermal shield will slow the probe to 400 meters per second within three minutes. Next comes deployment of a 2.6-meter pilot chute at 160 kilometers altitude. Within seconds, the pilot chute will pull off the probe's aft cover; the main parachute (8.3 meters) will then deploy before the front shield is released. At 110 kilometers, the main chute will be jettisoned; a smaller, 3-meter chute will then be deployed. The DISR instrument (Descent Imager/Spectral Radiometer) will switch on its lamp for surface illumination and...

ESA provides an interesting explanation of a question that had puzzled more than one reader: given that the Huygens probe provided no telemetry at the time, how did controllers know that its Christmas Eve separation from the Cassini orbiter had been nominal? It's true that Cassini was able to send data showing its own change in attitude due to the Huygens release, but how did we learn that Huygens was spinning at just the right rate (vital for a correct entry into Titan's atmosphere)? The answer: Huygens houses a weak magnetic field, despite attempts to render it 'magnetically clean' when it was constructed. The field is weak enough not to interfere with Cassini's sensitive instruments, but turns out to be measurable by its magnetometers. Cassini's Dual Technique Magnetometer (MAG) team used this data to establish the rate of Huygens' spin. From a news release from ESA: Professor Michele Dougherty, Principal Investigator for MAG, said, "What was observed by MAG just after the probe...

The Jet Propulsion Laboratory is offering this map of planned imaging coverage for the Huygens probe as it descends toward Titan's surface on Friday. Image: This map illustrates the planned imaging coverage for the Descent Imager/Spectral Radiometer, onboard the European Space Agency's Huygens probe during the probe's descent toward Titan's surface on Jan. 14, 2005. The Descent Imager/Spectral Radiometer is one of two NASA instruments on the probe. The colored lines delineate regions that will be imaged at different resolutions as the probe descends. On each map, the site where Huygens is predicted to land is marked with a yellow dot. This area is in a boundary between dark and bright regions. Credit: NASA/JPL/Space Science Institute. Click here for further information on the map and background about the descent. We are less than two days away from Huygens' entry into Titan's atmosphere, and Centauri Dreams seconds the JPL intro to this image: Go Huygens!

When the Huygens probe descends through Titan's atmosphere on January 14, only one optical instrument will be available for imaging. The Descent Imager/Spectral Radiometer (DISR) will take photographs of the surface during the two-hour descent, relaying the data to the Cassini orbiter for re-transmission to the Deep Space Network. Martin Tomasko of the University of Arizona's Lunar and Planetary Laboratory leads the international team in charge of DISR; he and other UA colleagues will head for the European Space Operations Center in Darmstadt, Germany next week. Key points: The Huygens probe should emerge from Titan's haze layer at an altitude of about 43 miles (70 kilometers), allowing the DISR instrument to get clear views of the descent and the surface below. The instrument's three cameras will take 750 images, which will be merged into a series of panoramic views of the ground and horizon. All DISR data will be relayed to Cassini at a height of 12 miles, to guard against the loss...

For the weekend, here is a first look at Iapetus from yesterday's Cassini flyby. JPL describes this as a raw image that "...has not been validated or calibrated." This image was taken on December 31, 2004 and received on Earth January 01, 2005. The camera was pointing toward IAPETUS at approximately 60,821 kilometers away, and the image was taken using the CL1 and CL2 filters. Credit: Jet Propulsion Laboratory. You can find more Iapetus images in the Cassini raw image beta page.

The dark terrain of the Cassini Regio on Iapetus will be the imaging target of the Cassini Saturn orbiter as it whisks past the moon at 2 kilometers per second later today. The Jet Propulsion Laboratory has released this map of the image coverage area. The regions Cassini will view at different imaging scales are shown within colored lines. These images were taken by Voyager in 1981; expect Cassini to deliver much better resolution, not only because of its superior optics, but also because of distance; Voyager passed Iapetus at over half a million miles, while Cassini will close to 76,700 miles (123,400 kilometers).

Cassini's post-Huygens separation maneuver occurred without incident on December 27. The course change was needed both to prevent Cassini from following the free-falling Huygens probe into Titan's atmosphere and to set up the required positioning for communications between Cassini and Huygens during the latter's atmospheric entry and descent. Cassini will make a close pass of Iapetus on December 31, and it should be worth watching. Iapetus (pronounced eye-APP-eh-tuss) is the third-largest of Saturn's moons, and it has already gained notoriety because of contrasts in its surface; one side is almost snow-bright, the other dark as tar. This has led to speculation that the surface is undergoing continual resurfacing due to processes that have yet to be identified. Above: Images obtained using ultraviolet (centered at 338 nanometers), green (568 nanometers) and infrared (930 nanometers) filters were combined to produce the enhanced color views at left and center; the image at the right...

The Huygens probe, captured in the photograph below as it departs from the Cassini Saturn orbiter, is now on course for its January 14th descent into Titan's atmosphere. Look for the probe in the upper right quadrant of the image. Huygens' separation from Cassini was achieved by firing explosive bolts; the probe was then pushed away by springs and rollers at roughly one foot per second. Image: The Cassini spacecraft snapped this image of the European Space Agency's Huygens probe about 12 hours after its release from the orbiter. The probe successfully detached from Cassini on Dec. 24, 2004, and is on course for its January 14 encounter with Titan. Credit: NASA/JPL. The journey to Titan's surface should be quite a ride. According to this European Space Agency release, the probe will enter the atmosphere on Titan's day side over its southern hemisphere. After the main parachute deploys, the probe will extend its instrument booms and begin collecting data about the moon's atmosphere....

The Huygens probe separation from the Cassini Saturn orbiter is scheduled to occur late this evening; according to this JPL press release, NASA expects a confirmation of the maneuver around 11 PM EST. The probe, which has been attached to Cassini for the seven-year trip to Saturn, has remained in sleep mode except for periodic 'awakenings' every six months to test its instruments. This evening, Huygens will be pushed away from the orbiter by tension-loaded springs and will begin its solo journey toward Titan, which it is expected to reach on January 14. Both Huygens and Cassini are at this point on an impact trajectory with Titan, to ensure the accuracy of the probe's arrival at the moon. On December 27, Cassini will change its course, putting it into proper position for radio communications during the probe's descent. The best source for Huygens information is either ESA's Cassini-Huygens page or NASA's Cassini page. The Cassini imaging team page is also well worth checking. While...

Cassini's most interesting view of Titan's atmosphere to date is shown here, highlighting what appears to be layer after layer of haze. The image is in the ultraviolet and taken from Titan's night side; the haze layers extend several hundred kilometers above the surface. The region shown here is in Titan's equatorial region, about 10 degrees south latitude. A nice wrap-up of Cassini data from both Titan and Dione, as presented at the American Geophysical Union's fall meeting in San Francisco, can be found on this JPL page. Especially noteworthy is the peculiar, braided character of the fractures on Dione's surface, where the terrain consists of ice cliffs apparently created by tectonic forces. "This is one of the most surprising results so far. It just wasn't what we expected," said Dr. Carolyn Porco, Cassini imaging team leader (Space Science Institute, Boulder, CO). We are now just three days away from the separation of the Huygens Titan probe from the Cassini orbiter, with descent...

The outer planets, worthy science targets in their own right, could also be considered something of a dry run for a true interstellar probe. And now details of a nuclear-powered mission to Neptune are beginning to emerge; they're coming out of a 12-month planning study funded by NASA and led by Boeing Satellite Systems. Particularly intriguing about Neptune is its moon Triton, which many scientists now believe to be a Kuiper Belt object, a planetoid not formed by Neptunian debris but captured long ago by the planet's gravity. A key part of the mission will be to deploy landers to Triton's surface. A December 17 session at the American Geophysical Union fall meeting will be another shakedown of the concept, which the Neptune team has been fine-tuning at various conferences (and how I missed this one in Centauri Dreams' earlier story on the AGU is beyond me). The session is "A Neptune/Triton Vision Mission Using Nuclear Electric Propulsion." Image: This picture of Neptune was produced...

Discovered in June of 2002, Quaoar is a large Kuiper Belt object roughly a billion miles beyond the orbit of Pluto, and although its size is still controversial, the best estimates make it out to be about half Pluto's diameter. Think of the Kuiper Belt as something similar to the Asteroid Belt, though containing up to 100 times more material. The region is critical to our understanding of the early Solar System because it seems to contain the System's most primitive materials. The fact that temperatures in the Kuiper Belt are as low as -50 K tells us that ices existing there should have been preserved since the dawn of planetary formation. Now a new study reporting near-infrared observations of Quaoar has revealed the presence of crystalline water ice and ammonia hydrate. Both, according to a letter by astronomers David Jewitt and Jane Luu that has just appeared in Nature, are peculiar. Crystallinity indicates that the ice has been heated to at least 110 K, and both water ice and...

We'll be watching two sessions at the upcoming fall meeting of the American Geophysical Union with special interest. One will be a briefing held at NASA headquarters on December 14 and available via satellite for a live question and answer period. The topic: the Deep Impact spacecraft, which will launch a copper projectile into the surface of Comet Tempel 1 on 4 July 2005. The 370 kilogram (820 pound) "impactor" is to hit the surface at some 37,000 kilometers (23,000 miles) per hour, creating a crater that could be over 100 meters in size. Data will be collected by Deep Impact's cameras and other instrumentation, to be supplemented by ground-based astronomy from Earth. The second session with outer Solar System implications, to be held on the 16th of December, will highlight the latest findings from Cassini as it again makes a Titan flyby, this one the last chance scientists will have to study the Huygens landing site before that probe's January descent. Two days later, on the 15th,...