BY SPACEFLIGHT NOW

Follow the Huygens probe's descent to the surface of Saturn's moon Titan! Reload this page for the latest on the mission.

SATURDAY, JANUARY 15, 2005

A missing computer command - apparently the result of human error - caused the loss of half the pictures taken by Europe's Huygens probe as it descended to the surface of Saturn's moon Titan. But project officials said today the 350 pictures that made it back, along with high-quality data from the spacecraft's other instruments and unexpected measurements by Earth-based radio telescopes, should fulfill all of the mission's primary objectives.

Read our full story.

Also, you can see our montage of Huygens pictures showing the landing area here.

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VIDEO: THE NEW PICTURES PRESENTED WITH EXPERT NARRATION QT
VIDEO: LISTEN TO SOUNDS FROM HUYGENS WITH NARRATION QT
AUDIO: LISTEN TO SOUNDS FROM HUYGENS WITH NARRATION FOR IPOD
VIDEO: RESULTS FROM HUYGENS' SURFACE SCIENCE PACKAGE QT
VIDEO: CHIEF SCIENTIST EXPLAINS COMMUNICATIONS ERROR QT
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2015 GMT (3:15 p.m. EST)

Here is a press statement from Lockheed Martin:

"After over seven years in space, the European Space Agency's (ESA) Huygens probe has descended through the atmosphere of Titan, the largest of Saturn's multitude of moons.

"Pictures of Titan's exotic environment were provided by the Descent Imager/ Spectral Radiometer (DISR), a complex instrument designed and built by Lockheed Martin for the University of Arizona and the NASA Jet Propulsion Laboratory (JPL). NASA's Cassini spacecraft, with the Huygens probe in tow, was inserted into orbit around Saturn on June 30, 2004, initiating four years of orbital science investigations of the giant ringed planet and its many mysterious moons.

"We couldn't be more pleased for our colleagues at the University of Arizona, NASA and ESA as Huygens has allowed us unprecedented access to one of the most mysterious moons in the solar system,' said James Crocker, vice president, Civil Space, at Lockheed Martin Space Systems Company. 'The superb performance of the DISR hardware and the many years of hard work by the DISR team are equally gratifying, and we're proud to play a role in this exciting international voyage of exploration.'

"As Huygens descended by parachute through Titan's thick atmosphere, DISR made a range of imaging and spectral observations using several sensors and fields of view. The radiation balance of the atmosphere was measured by monitoring the upward and downward flow of radiation. A calculation of the size, number and density of suspended particles in the atmosphere was made possible by measuring the light intensity around the Sun. Two imagers (one visible, one infrared) observed the surface during the latter stages of the descent, and built up a mosaic of pictures around the touch down site. A side-view visible imager captured a horizontal view of the horizon and the underside of the cloud deck. The spectral measurements of the surface were enabled by a lamp that switched on shortly before touch down to augment the weak sunlight.

"The study of Titan, Saturn's largest moon, is one of the major goals of the Cassini/Huygens mission. Although it is believed to be too cold to support life, haze-covered Titan may preserve, in deep-freeze, many of the same chemical compounds that preceded life on Earth. The Huygens descent and touch down is the most distant descent by a robotic probe ever attempted on another object in the solar system. Over the course of the orbital mission, Cassini will have executed 45 flybys of Titan, coming as close as approximately 590 miles (950 km) above the surface.

"This will permit high-resolution mapping of the moon's surface with an imaging radar instrument, which can see through the opaque haze of Titan's upper atmosphere.

"The second largest planet in our solar system, after Jupiter, Saturn serves as a natural laboratory to better understand the formation of our Solar System five billion years ago, as the planet and its rings are a close analog to the disc of gas and dust surrounding the nascent Sun that formed the planets. Detailed knowledge of the dynamics of interactions among Saturn's elaborate rings and numerous moons will provide valuable data for understanding how each of the solar system's planets evolved.

"The Cassini spacecraft was launched on a Lockheed Martin-built Air Force Titan IV/Centaur rocket Oct. 15, 1997. The Cassini propulsion module - also built by Lockheed Martin - is the largest U.S. planetary spacecraft propulsion system ever built, and was fired 17 times en route to Saturn, and will be ignited approximately 150 more times before the end of the mission. In addition to DISR, the Titan IV/Centaur and the propulsion system, Lockheed Martin Space Systems Company designed and built the three radioisotope thermoelectric generators (RTGs) that power spacecraft systems.

"JPL designed, developed and assembled the Cassini orbiter. ESA managed the development of Huygens and is in charge of operations of the probe from its control center in Darmstadt, Germany. The Italian Space Agency provided the high-gain antenna, much of the radio system and elements of several of Cassini's science instruments. JPL manages the overall program for NASA's Office of Space Science, Washington, D.C."

1135 GMT (6:35 a.m. EST)

Tired and weary after a sleepless night spent sorting through their data, scientists today unveiled more pictures returned from the European Space Agency's Huygens probe that landed on Saturn's moon Titan Friday.

   PHOTO: TITAN IN COLOR
   PHOTO: SIZES OF SURFACE FEATURES
   PHOTO: OVERHEAD VIEW OF TERRAIN
   PHOTO: MOSAIC OF MANY IMAGES

1040 GMT (5:40 a.m. EST)

An apparently missing command caused the loss of Huygens' Channel A data stream during descent to Titan yesterday, prompting ESA to form an investigation into the error. The Channel B data link worked, allowing over 300 pictures and information from the probe's instruments to be relayed up to the Cassini orbiter.

With two data paths, scientists had their choice of either relaying the same set of pictures to Cassini twice for redundancy or taking two sets of pictures to maximize the potential number of images. They opted to acquire two sets of pictures, and the lack of Channel A caused half of the expected number of pictures from Huygens to be lost.

The Channel A problem also resulted in the loss of data for the Doppler wind experiment between Huygens and Cassini. But ESA's chief scientist says data from radio telescopes on Earth that were listening to the tones from Huygens should allow researchers to complete the winds experiment.

FRIDAY, JANUARY 14, 2005

Initial pictures of Saturn's moon Titan snapped by Europe's Huygens probe during its historic atmospheric descent and touchdown today show an active world likely carved by the flow of cryogenic liquids that may still pool on its frigid surface, a leading planetary scientist says.

Read our full story.

Video coverage for subscribers only:
VIDEO: THE FIRST PICTURE FROM HUYGENS IS REVEALED QT
VIDEO: OFFICIALS OFFER THOUGHTS AFTER SEEING PICTURE QT
VIDEO: HUYGENS POST-LANDING BRIEFING DIAL-UP | BROADBAND
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VIDEO: STATUS REPORT DURING DESCENT DIAL-UP | BROADBAND
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VIDEO: HUYGENS PRE-ARRIVAL NEWS BRIEFING DIAL-UP | BROADBAND
AUDIO: HUYGENS PRE-ARRIVAL NEWS BRIEFING FOR IPOD

VIDEO: OVERVIEW OF HUYGENS PROBE'S SCIENCE OBJECTIVES QT
VIDEO: JULY NEWS BRIEFING ON CASSINI'S PICTURES OF TITAN QT
VIDEO: PICTURES SHOWING TITAN SURFACE FROM OCT. FLYBY QT
VIDEO: WHAT'S KNOWN ABOUT TITAN BEFORE THE FIRST FLYBY QT
VIDEO: NARRATED MOVIE OF CLOUDS MOVING NEAR SOUTH POLE QT
VIDEO: OCT. BRIEFING ON RADAR IMAGES OF TITAN SURFACE QT
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2225 GMT (5:25 p.m. EST)

ESA has not released any additional pictures. Another report is scheduled for 1000 GMT (5 a.m. EST) on Saturday.

2129 GMT (4:29 p.m. EST)

The European Space Agency unveiled the first raw images from the Huygens Titan probe today, black-and-white pictures showing ice blocks strewn across the surface and hard-to-interpret features resembling drainage channels and, possibly, a frigid shoreline of sorts.

Read our full story.

2043 GMT (3:43 p.m. EST)

An extraordinary raw picture returned from Huygens shows the view from Titan's surface. You can see the picture here.

2005 GMT (3:05 p.m. EST)

There was just one picture released so far. European Space Agency plans to unveil more photos about two hours from now.

2002 GMT (3:02 p.m. EST)

You can see the first picture here. It was taken at an altitude of 16 km as Huygens made its descent.

1956 GMT (2:56 p.m. EST)

The first image shows what appear to be drainage channels flowing to a possible shoreline, the camera's scientist says. The pictures are raw and unprocessed.

1955 GMT (2:55 p.m. EST)

The first picture from the descending Huygens probe showing the Titan surface has been revealed in mission control!

1930 GMT (2:30 p.m. EST)

ESA has released some quote by various officials following today's landing on Titan:

"This is a great achievement for Europe and its U.S. partners in this ambitious international endeavour to explore the Saturnian system," said Jean-Jacques Dordain, ESA's director general.

"Titan was always the target in the Saturn system where the need for 'ground truth' from a probe was critical. It is a fascinating world and we are now eagerly awaiting the scientific results," says Professor David Southwood, director of ESA's scientific program.

"The Huygens scientists are all delighted. This was worth the long wait," says Dr Jean-Pierre Lebreton, ESA Huygens mission manager. Huygens is expected to provide the first direct and detailed sampling of Titan's atmospheric chemistry and the first photographs of its hidden surface, and will supply a detailed 'weather report.'

One of the main reasons for sending Huygens to Titan is that its nitrogen atmosphere, rich in methane, and its surface may contain many chemicals of the kind that existed on the young Earth. Combined with the Cassini observations, Huygens will afford an unprecedented view of Saturn's mysterious moon.

"Descending through Titan was a once-in-a-lifetime opportunity and today's achievement proves that our partnership with ESA was an excellent one," says Alphonso Diaz, NASA associate administrator of science.

"The teamwork in Europe and the USA, between scientists, industry and agencies has been extraordinary and has set the foundation for today's enormous success," concludes Jean-Jacques Dordain.

1800 GMT (1:00 p.m. EST)

Robert Mitchell, NASA's Cassini program manager at the Jet Propulsion Laboratory in Pasadena, Calif., says the loss of one telemetry stream from the Huygens Titan probe appears to be the result of an actual problem of some sort on board the spacecraft.

Read our update story.

1745 GMT (12:45 p.m. EST)

There will be a pause in live reports from ESA while the rest of the data is downlinked from Cassini and scientists have a chance to begin examining the mounds of information. The next event is expected after 1945 GMT (2:45 p.m. EST) with some initial science news, potentially the first pictures from Huygens. We'll be posting them here as soon as they are released.

1722 GMT (12:22 p.m. EST)

NASA's Cassini Saturn orbiter began downlinking science data from the European Space Agency's Huygens probe at 11:19 a.m. EST (1619 GMT), confirming the spacecraft not only survived its high-speed plunge into the atmosphere of Saturn's moon, Titan, but that its instruments worked to remotely explore one of the strangest worlds in the solar system.

Read our update story.

1706 GMT (12:06 p.m. EST)

Engineers says the Channel A and Channel B data paths from Huygens are redundant with the exception that Channel A is needed for the Doppler wind experiment with the Cassini orbiter. The Channel A telemetry stream isn't working as expected, but Channel B appears normal, ESA says.

1701 GMT (12:01 p.m. EST)

The temperature inside the probe was 25 degrees C as it was descending through 50 km altitude, the ongoing data review shows.

1658 GMT (11:58 a.m. EST)

The probe went through the entry phase, the parachute deployment was within 15 seconds of the planned time and onboard accelerometer data worked normally, officials are saying at the news conference. The playback of data continues.

1655 GMT (11:55 a.m. EST)

ESA says data is being received normally on the Channel B telemetry steam. However, the Channel A has a question mark surrounding it.

1645 GMT (11:45 a.m. EST)

Here is a press statement from Alcatel:

"The Huygens space probe has arrived on Titan. The probe was built by prime contractor Alcatel Space, a subsidiary of Alcatel, leading a consortium of 40 companies and laboratories. Alcatel Space is the first European company to have met the challenge of constructing a spacecraft designed to resist such draconian conditions. This is the first time that a man-made object has landed on the moon of a planet so far away in our solar system. This is also the first time that an European probe has successfully landed on another part of the solar system.

"The interplanetary voyage of Cassini/Huygens took seven years, and made use of successive gravity boosts from Venus (twice), the Earth and Jupiter. Huygens had to stand up to temperatures of 212 deg F near Venus, and made a blind crossing of the asteroid belt between Mars and Jupiter, then the rings of Saturn. However, the technical challenge reached its zenith during the descent towards Titan, which lasted nearly three weeks after the separation from the Cassini mother-craft on December 25. Following aerodynamic braking in the upper atmosphere, then deployment of three parachutes to control the descent, the probe landed on the surface of Titan. Huygens is a veritable flying lab, featuring six advanced instruments to carry out all measurements expected by the scientific community.

"Meanwhile, Cassini is in orbit around Saturn for its own observation mission, while relaying data from Huygens back to Earth.

"The Cassini/Huygens programs was an unprecedented technical challenge, tackling aspects that had never before been studied:

• Major restrictions on mass and energy, given the distance to be traveled and the complex trajectory needed to reach Saturn via gravity boosts form Venus, Earth and Jupiter.
• Completely autonomous operation.
• High-precision Cassini/Huygens separation maneuvers.
• Thermal shield adapted to an entry into Titan's atmosphere.
• Parachute deployment at supersonic speed.
• Sufficient robustness to stand up to unknown elements, especially atmospheric (furthermore, scientists have continuously changed their models since the knowledge of Titan was increased, which required an important effort to ensure successful entry).

"We are especially proud of this huge success by our customer ESA, in partnership with NASA and ASI," said Pascale Sourisse, Chairman and CEO of Alcatel Space. "Not only is it a world first in exploration of the universe, it also marks a major step forward in better understanding the origins of life. With the Huygens mission now accomplished, we want to reaffirm our unyielding commitment to carrying out the most demanding programs for interplanetary exploration and observation of the universe, alongside European scientists and space agencies. We hope that this mission will pave the way to other adventures that prove to be just as exciting, both scientifically and technologically."

1635 GMT (11:35 a.m. EST)

The news briefing has begun.

"We have a scientific success," ESA director general Jean-Jacques Dordain reports. "We are the first visitors of Titan."

1630 GMT (11:30 a.m. EST)

We're awaiting the start of a planned news conference. The top science officials from ESA and NASA were in the room and then left.

1619 GMT (11:19 a.m. EST)

The Huygens data is being received! Applause has erupted in the German control room after the tense and anxious wait. It will take some time to begin examining the information. The first pictures from Huygens could be released later today, if all has gone well.

1605 GMT (11:05 a.m. EST)

Scientists, engineers and senior officials have gathered in a large crowd within the European mission control center. Everyone is nervously awaiting the first bits of data from Huygens.

1545 GMT (10:45 a.m. EST)

NASA's Cassini Saturn orbiter has turned back toward Earth and started transmitting stored data from Europe's Huygens probe, which was still broadcasting a faint carrier signal from the surface of the moon Titan more than two hours after touching down and well after Cassini had turned away.

Read our update story.

1530 GMT (10:30 a.m. EST)

Scientists have another 40 minutes of suspense before the first Huygens data arrives on Earth, which will confirm probe's transmissions to Cassini and recording aboard the orbiter has worked.

1526 GMT (10:26 a.m. EST)

The communications link between Cassini and Earth has been established.

1510 GMT (10:10 a.m. EST)

"This is clearly an engineering success and we know the probe has been successfully entering the atmosphere, has been descending on the parachute to the surface," said Jean-Pierre Lebreton, ESA's Huygens project scientist.

"But at this moment we cannot say more. I mean, we have not seen the data. What we have seen is a tone, a signal, which was indicating that the probe was transmitting but we have not seen any real data yet. So I would like to wait a bit more to say whether we have a successful mission or not."

The first Huygens data via the Cassini telemetry playback is expected in about an hour.

1501 GMT (10:01 a.m. EST)

A tone is still being emitted from Huygens and detected by radio telescopes on Earth, now more than two hours after landing. Meanwhile, Cassini has turned away from Huygens to re-point its communications antenna for relay of data to Earth.

1445 GMT (9:45 a.m. EST)

Here is the press statement issued by the European Space Agency:

"The Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, USA, a part of the global network of radio telescopes involved in tracking the Huygens Titan probe, has detected the probe's 'carrier' (tone) signal.

"The detection occurred between 11:20 and 11:25 CET (5:20-5:25 a.m. EST), shortly after the probe began its parachute descent through Titan's atmosphere. The extremely feeble signal was first picked up by the Radio Science Receiver supplied by the NASA Jet Propulsion Laboratory. This signal is an important indication that the Huygens probe is 'alive'. However, it does not contain yet any substance; the latter is expected to come a few hours later via the Cassini spacecraft.

"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.

"Only after having received the data packets at ESOC will it be possible to say with certainty whether data were properly acquired. The first data set from Cassini will reach ESOC in the afternoon. Additional downlinks will follow throughout the evening and night for redundancy.

"Further analysis of the signals will be conducted using other three independent data acquisition systems at the Green Bank Telescope. In addition to the GBT, sixteen other radio telescopes in Australia, China, Japan and the USA are involved in tracking the Huygens probe.

"The ultimate goal of the tracking experiment is to reconstruct the probe's descent trajectory with an unprecedented accuracy of the order of one kilometre. The measurements will be conducted using Very Long Baseline Interferometry (VLBI) and Doppler tracking techniques. This would enable studies of the dynamics of Titan's atmosphere, which is considered to be a 'frozen' copy of that of the early Earth.

"The VLBI component of the tracking experiment is coordinated by the Joint Institute for VLBI in Europe (JIVE) and ESA; the Doppler measurements are conducted by the Jet Propulsion Laboratory."

1403 GMT (9:03 a.m. EST)

Huygens remains alive and sending its beeping signal from the surface -- more than an hour after controllers calculate it landed. The relay of science data to Cassini concludes later this hour as the orbiter goes over the horizon from the landing site.

The first science information is expected on Earth about two hours from now.

1332 GMT (8:32 a.m. EST)

Mission controllers say the tone from Huygens is still being received! The craft appears to have landed around 1245 or 1246 GMT (7:45 or 7:46 a.m. EST) on Titan and continues to operate from the moon's surface.

1300 GMT (8:00 a.m. EST)

A huge radio telescope at Green Bank, West Virginia, was able to detect and lock onto a faint carrier signal from the Huygens Titan probe for more than two hours this morning, confirming the spacecraft's continued descent through the moon's atmosphere following a high-speed entry.

A second radio telescope now has picked up the signal as well and Europoean Space Agency project scientist Jean-Pierre Lebreton said engineers were even able to confirm at least one of the probe's six on-board instruments had activated as planned.

Read our full story.

1115 GMT (6:15 a.m. EST)

Huygens should be continuing its long, parachute-aided fall to the surface of Titan, with the large suite of science instruments operating to study the atmosphere and obtain volumes of pictures. Huygens is doing its work out of view from mission control. Real-time confirmation that the science program is being performed is not available because the craft is sending the information directly to the Cassini orbiter, which itself has turned away from Earth to receive the Huygens data.

Earlier, controllers heard a simple tone emitted from Huygens that did announce the craft was at least alive.

A news conference is coming up at 1230 GMT (7:30 a.m. EST). Cassini will resume communications with Earth about three hours later, and the data playback will continue for several hours.

1033 GMT (5:33 a.m. EST)

SIGNAL FROM HUYGENS! A radio telescope on Earth has detected a faint signal from the descending Huygens spacecraft, confirming the probe is alive, has survived its super-hot entry into the atmosphere and should be carrying out its scientific exploration on the way to the surface of Saturn's moon Titan.

This is just a signal with no actual data included. The data is being relayed to the Cassini orbit and will be played to Earth later today.

Nonetheless, the fact that a signal has been received to verify that Huygens is functioning prompted screams and cheers in mission control.

THURSDAY, JANUARY 13, 2005

The European Space Agency's Huygens probe, closing in on Saturn's mysterious moon Titan, is racing toward a dramatic, high-speed plunge into the moon's thick nitrogen atmosphere early Friday for a long-awaited parachute descent to an enigmatic surface.

Released from NASA's Cassini Saturn orbiter on Christmas Eve, the flying saucer-shaped probe is targeted to slam into Titan's atmosphere at a velocity of 12,400 mph at 5:13 a.m. EST (1013 GMT).

Over the next three to four minutes, the 705-pound probe is expected to endure peak heating of nearly 3,500 degrees and a braking force of some 16 Gs, slowing the craft to a more sedate 895 mph. At that point - 5:17 a.m. - the probe should release a small 8.5-foot pilot chute that will pull away a protective rear cover.

Just 2.5 seconds later, the craft's 27.2-foot-wide main parachute will unfurl. For the first time since pre-release tests, an on-board radio will begin transmitting data to Cassini around 5:18 a.m. as the NASA spacecraft streaks past Titan some 37,000 miles away.

Huygens is expected to reach the surface of Titan around 7:31 a.m. But with its main antenna pointed toward the landing zone, Cassini will be out of contact with Earth, leaving anxious engineers and scientists in the dark until the NASA craft turns back toward Earth and begins transmitting recorded data around 10:17 a.m. That's nearly three hours after Huygens touches down.

Read our full story.

WEDNESDAY, JANUARY 12, 2005

In one of the boldest space missions ever attempted, a small European-built probe will slam into the atmosphere of Saturn's mysterious moon Titan Friday for a two-and-a-half hour parachute descent to its smog-shrouded surface.

Beaming pictures and a torrent of data to NASA's Cassini Saturn orbiter, the flying saucer-shaped Huygens probe will give scientists their first close-up look at one of the largest expanses of unexplored territory in the solar system.

Researchers are hopeful Huygens will answer their most pressing questions: whether hydrocarbons fall like rain and form pools of liquid ethane and similar compounds on the moon's frigid surface; and what erosional or depositional processes are responsible for covering up impact craters and producing a relatively flat, mountain-free surface.

No matter what Huygens actually sees on the surface, scientists expect to gain insights into the workings of a thick, complex atmosphere that in some respects mirrors Earth's shortly after the planet's birth.

Read our full story.

Read our earlier status center coverage.