BY JUSTIN RAY

Reload this page for updates on the NASA Stardust spacecraft's close encounter for Comet Wild 2.

Video coverage for subscribers only:
   VIDEO: STARDUST SURVIVES CLOSEST APPROACH TO COMET QT
   VIDEO: FIRST IMAGES RELEASED AT NEWS CONFERENCE QT

   VIDEO: PRE-ENCOUNTER INTERVIEW WITH PROJECT MANAGER QT
   VIDEO: MISSION PLANNER DESCRIBES STARDUST'S CHALLENGES QT
   VIDEO: DESCRIPTION OF THE STARDUST SCIENCE PROGRAM QT
   VIDEO: REPORT ON THE STARDUST SCIENCE INSTRUMENTS QT
   VIDEO: INTERVIEW EXPLAINS STARDUST'S CAMERA SYSTEM QT
   VIDEO: LEARN MORE ABOUT THE EXOTIC AEROGEL MATERIAL QT
   VIDEO: AN INTERVIEW WITH STARDUST'S NAVIGATOR QT
   VIDEO: A LOOK AHEAD TO DEEP IMPACT COMET MISSION QT

   VIDEO: OVERVIEW OF THE SEVEN-YEAR STARDUST MISSION QT
   VIDEO: ANIMATION OF STARDUST COLLECTING COMET SAMPLES QT
   VIDEO: STARDUST RETURNS TO EARTH AND PARACHUTES TO UTAH QT
   VIDEO: ENCOUNTER DETAILED BY 39-MINUTE NEWS CONFERENCE QT
   ADDITIONAL VIDEO COVERAGE
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FRIDAY, JANUARY 2, 2004

The Stardust probe flew through at least two significant jets of debris during its approach to comet Wild 2 today and captured a stunning image of the comet's icy heart showing overlapping pits and depressions where material boiled off in the past. At least five active jets can be seen in the black-and-white navigation camera image, along with a huge, partially shadowed pit that would hold dozens of Rose Bowl stadiums. Read full story.

2357 GMT (6:57 p.m. EST)

"Things couldn't have worked better in a fairy tale," says Tom Duxbury, the Stardust project manager.

Today the spacecraft flew within 149 miles (240 kilometers) of Comet Wild 2 to collect dust samples and snap images of the nucleus.

"These images are better than we had hoped for in our wildest dreams," said Ray Newburn, a co-investigator for Stardust. "They will help us better understand the mechanisms that drive conditions on comets."

"These are the best pictures ever taken of a comet," added scientist Don Brownlee. "Although Stardust was designed to be a comet sample return mission, the fantastic details shown in these images greatly exceed our expectations."

"Everything occurred pretty much to the minute. And with our cometary encounter complete, we invite everybody to tune in about one million, 71 thousand minutes from now when Stardust returns to Earth, bringing with it the first comet samples in the history of space exploration," Duxbury said.

2305 GMT (6:05 p.m. EST)

NASA has released the first image of Comet Wild 2's icy nucleus as seen by the Stardust spacecraft today. See the image here.

2130 GMT (4:30 p.m. EST)

Blasted by icy particles striking at 4 miles per second -- six times faster than a rifle bullet -- NASA's armored Stardust probe flew within 150 miles of a 3-mile-wide comet today, capturing primordial debris left over from the birth of the solar system 4.2 billion years ago.

Engineers monitoring radio signals from the spacecraft erupted in cheers and applause as the moment of closest approach came and went with little or no degradation in the stream of data flowing back to Earth. That steady signal meant Stardust had survived its unprecedented encounter with comet Wild-2, the culmination of a five-year voyage spanning more than 2 billion miles since blastoff in February 1999.

Read full story.

2015 GMT (3:15 p.m. EST)

NASA's Stardust spacecraft successfully survived its risky close approach to the icy heart of Comet Wild 2 today on a first-of-its-kind quest to collect samples for return to Earth.

Comets are considered ancient relics that serve as frozen time capsules from a time billions of years ago when our solar system was forming. Stardust will ferry the samples to Earth for scientists to study.

"This could prove to be a pivotal time for science, a remarkable opportunity to gather evidence that might actually tell us how the planets formed and give us clues about how life on Earth began," says Donald Brownlee, a University of Washington astronomer and chief investigator for the Stardust mission.

Stardust's package of samples will land in Utah on January 15, 2006.

2000 GMT (3:00 p.m. EST)

Another poll of the flight controllers was just conducted.

"It looks like once again the spacecraft has performed in an outstanding manner and done everything we have asked it to do. All subsystems are nominal, and we will begin our (data) playback within the next five minutes," mission control reports.

A post-encounter news conference is scheduled for 2300 GMT (6 p.m. EST) for officials to announce details and hopefully release some images of the flyby. Watch this page for continuing updates this evening!

1952 GMT (2:52 p.m. EST)

"Everything, so far, has gone by the book," Stardust project manager Tom Duxbury reports from Mission Control.

"Life is tremendously good. We have flown through the worst of it and we are still in contact with our spacecraft...The history that we just made will evolve in about two years when we land."

1950 GMT (2:50 p.m. EST)

Stardust's navigation camera should be ending its sequence of highest-frequency image-taking of the comet. Upcoming, the spacecraft will roll back into an orientation to point its high-gain communications antenna to Earth to resume full telemetry relay to Mission Control.

1947 GMT (2:47 p.m. EST)

"So far, so good," NASA officials report from JPL. The signal from Stardust is still being received on Earth, confirming that the spacecraft has survived its flight past the comet's nucleus.

1945 GMT (2:45 p.m. EST)

Applause has erupted in the control room at NASA's Jet Propulsion Laboratory -- now one minute after the point of closest approach.

1944 GMT (2:44 p.m. EST)

CLOSEST APPROACH. The Stardust spacecraft is now passing the icy heart of Comet Wild 2. The aliveness tone from the craft is continuing to be received on Earth.

1940 GMT (2:40 p.m. EST)

Stardust is storing all of the images, plus the data from its Dust Flux Monitor and Comet and Interstellar Dust Analyzer. All of this information will be relayed to Earth beginning later today.

1939 GMT (2:39 p.m. EST)

With five minutes remaining to closest approach, the navigation camera increases its rate of picture-taking to one every 10 seconds.

1938 GMT (2:38 p.m. EST)

The Stardust spacecraft should be performing a planned 30-second roll maneuver to keep the comet nucleus within the navigation camera's field-of-view during encounter. Leading up to this time, the camera's scanning mirror to gradually pan as the comet passes by. During closest encounter, the spacecraft will perform a roll to keep the camera pointed at the comet.

1937 GMT (2:37 p.m. EST)

The planned loss-of-signal from the spacecraft has happened as Stardust switches from its high-gain antenna to a carrier signal for the encounter. This transition means the craft is no longer transmitting scientific or engineering data. Stardust returns to the high-gain antenna several minutes after the closest approach.

1934 GMT (2:34 p.m. EST)

Stardust is now just 10 minutes from the nearest point to Comet Wild 2 -- estimated to be about 143 miles.

1931 GMT (2:31 p.m. EST)

A poll of ground controllers was just performed. The attitude, propulsion, power, thermal, flight software, telecomm, navigation, fault protection and other systems are all reported normal.

The spacecraft is approximately 3,500 miles to the closest approach.

1929 GMT (2:29 p.m. EST)

With 15 minutes remaining before the flyby, the spacecraft should be turning on the Dust Flux Monitor instrument. The Dust Flux Monitor measures the size and frequency of dust particles in the comet's coma.

Here is NASA's explanation of the device.

"The instrument consists of two film sensors and two vibration sensors. The film material responds to particle impacts by generating a small electrical signal when penetrated by dust particles. The mass of the particle is determined by measuring the size of the electrical signals. The number of particles is determined by counting the number of signals. By using two film sensors with different diameters and thicknesses, the instrument will provide data on what particle sizes were encountered and what the size distribution of the particles is.

"The two vibration sensors are designed to provide similar data for larger particles, and are installed on the Whipple shield that protect the spacecraft's main bus. These sensors will detect the impact of large comet dust particles that penetrate the outer layers of the shield. This system, essentially a particle impact counter, will give mission engineers information about the potential dust hazard as the spacecraft flies through the coma environment. Co-investigator in charge of the Dust Flux Monitor is Dr. Anthony Tuzzolino of the University of Chicago, where the monitor was developed."

1925 GMT (2:25 p.m. EST)

The moment of closest approach for Stardust should have occurred by now. However, events at the spacecraft are occurring about 20 minutes before data to confirm the activities are received on Earth.

1919 GMT (2:19 p.m. EST)

NASA is not reporting any problems or concerns as Stardust prepares for the comet encounter.

1914 GMT (2:14 p.m. EST)

T-minus 30 minutes and counting. Stardust will make its closest approach to the icy core of Comet Wild 2 at 2:44 p.m. EST (Earth Receive Time).

At this point in the encounter, the spacecraft's navigation camera is scheduled to increase the frequency of its image-taking to the rate of nearly one every 30 seconds.

1912 GMT (2:12 p.m. EST)

In an effort to get the public excited about the Stardust mission, the project sponsored a "Send Your Name to a Comet" campaign that invited people from around the world to submit their names via the Internet to fly onboard the spacecraft. Two microchips bearing the names of more than 1.1 million people are on the Stardust, riding the spacecraft through today's encounter.

The names were electronically etched onto fingernail-size silicon chips at a microdevices laboratory at JPL. The lettering on the microchips is so small that about 80 letters would equal the width of a human hair. The names can be read only with the aid of an electron microscope.

The first Stardust microchip contains 136,000 names collected in 1997 from persons all over the world. That microchip has been placed inside the sample return capsule.

The second microchip contains more than a million names from members of the public, and was placed on the back of the arm that holds the dust collector. In addition to holding names from the public at large, the second microchip contains all 58,214 names inscribed on the Vietnam Veterans Memorial in Washington, D.C., as a tribute to those who died in that war.

1908 GMT (2:08 p.m. EST)

The spacecraft and comet are now about 7,550 miles apart, closing at a rate of 3.8 miles per second.

1904 GMT (2:04 p.m. EST)

Stardust is over 8,000 miles from Wild 2, closing at 3.8 miles per second, Mission Control reports.

1901 GMT (2:01 p.m. EST)

Based on the trajectory of Stardust relative to Comet Wild 2, the point of closest approach is expected to be 2:44 p.m. EST (Earth Receive Time) at a distance of 143 miles. That is a few minutes later and about 40 miles closer than originally announced by NASA.

1850 GMT (1:50 p.m. EST)

Mission scientists call Comet Wild 2 "one hell of a comet." It is reachable for this low-cost spacecraft and has made only a few trips close to the Sun when the frozen records from the formation of our solar system are gradually lost. You can read more about Stardust's comet here.

1830 GMT (1:30 p.m. EST)

Comet Wild 2 is faster than the Stardust spacecraft travels. In designing this mission, the challenge was getting Stardust to a position in time and space so the comet can "run over" it.

The comet will approach Stardust from outside and below the spacecraft's orbital plane. Stardust is flying backwards with its nose pointed down so its protective shielding can guard it from the expected "hailstorm of particles." The comet will overtake the spacecraft and continue on its orbital path, which will carry it above and inside the trajectory of Stardust.

"Navigators were further tasked to have this brief meeting of spacecraft and comet occur on the sunlit side of the comet, so that the Sun could act as a natural flashbulb for picture-taking and because that is where the majority of comet particle are expected to be found," NASA says.

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

Stardust's orientation as it flies through space is managed by the attitude control system. Despite taking a beating by the dust particles today, officials are confident that the spacecraft will remain steady during the flyby.

"We have designed the attitude control system to take the worst that we think Wild 2 has to throw at us. We have done all types of modelings and looked at the size, size distribution and spatial distribution of these particles that will hit the spacecraft," says Tom Duxbury, the Stardust project manager.

"We have taken the worst case, which we think is a centimeter-sized particle, and we have shot that at six times the speed of a bullet at our shielding and the shielding indeed does stop this.

"Does this guarantee that we can stop everything? We believe that the design is such that it will do so. However there are no guarantees -- there is some risk. I would like to tell you the risk is zero but it is not. The probability of being impacted by a centimeter-sized particle or larger is on the order of one percent or less."

1730 GMT (12:30 p.m. EST)

Stardust's encounter with Comet Wild 2 is now about two hours away. Here are some thoughts from Don Brownlee, the Stardust chief investigator from the University of Washington, about the reason for returning samples from a comet.

"Comets are among the most beautiful astronomical things we ever see in the nighttime sky. But in addition to being beautiful, they are extremely important because they are containers, sort of like museums, that have preserved the fundamental building blocks that our solar system, our planet and even ourselves were made of.

"We are star dust. Atoms inside our bodies, before the solar system formed, were in star dust or interstellar gains before the Sun formed. We believe these are still preserved inside comets."

The spacecraft is gathering these incredibly tiny dust particles today. The material will be brought back to Earth for scientists to examine at the atomic scale, looking at the elemental composition and mineralogical and chemical properties.

"In a real sense...we are traveling back in time billions of years to a time when the Sun and Earth and the other planets formed."

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

"Navigation to a comets is not an easy task. Comets are very small, they are very dark objects, they are shrouded by this big coma. Trying to hunt down the nucleus in that coma is not particularly easy," says Shyam Bhaskaran, the Stardust mission navigator.

"Our goal here is to fly by at 300 kilometers, and we have to hit a corridor about 16 km in diameter -- 300 km from the nucleus. That is not an easy task."

Stardust's navigation camera is the vital device to guide the spacecraft during the mission.

"With Mars and other planets, we know relatively well where the planets are. This is not the case with comets, which are not easily observed because they are small objects with gas jets. It is much harder to predict their orbits, which is why we have a little extra help from a camera onboard the spacecraft."

The camera has snapped views of the comet over the past few weeks. The frequency of picture-taking continues to increase -- from twice per week to one every 10 seconds during the final approach this afternoon.

While conducting distant imaging of the comet's coma, the camera will take pictures through a periscope in order to protect the camera's primary optics as the spacecraft enters the coma. In the periscope, light is reflected off mirrors made of highly polished metals designed to minimize image degradation while withstanding particle impacts.

During close approach, the nucleus is tracked and several images taken with a rotating mirror that no longer views through the periscope.

According to NASA, the camera is put together from flight-ready hardware left over from other missions. The main camera is a spare wide-angle unit left over from the two Voyager spacecraft missions launched to the outer planets in 1977. The camera uses a single clear filter, thermal housing and spare optics and mechanisms. For Stardust, designers added a thermal radiator. Also combined with the camera is a modernized sensor head left over from the Galileo mission to Jupiter launched in 1989. The sensor head uses the existing Galileo design updated with a 1024-by-1024-pixel array charge-coupled device (CCD) from the Cassini mission to Saturn, but has been modified to use new miniature electronics. Other components originated for NASA's Deep Space 1 program.

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

It is T-minus 4 hours and counting to Stardust's intercept of Comet Wild 2. The spacecraft should be less than 60,000 miles away from the comet, continuing to move toward a 185-mile flyby distance.

Stardust has entered the "close encounter" phase of the mission, which covers the five hours before and after the comet flyby. These 10 hours will fulfill the scientific goal of the seven-year expedition of Stardust by collecting comet dust for return to Earth in 2006.

0501 GMT (12:01 a.m. EST)

The Stardust space probe is headed for the defining moment of its $168 million, seven-year mission to gather particles swirling around the heart of Comet Wild 2.

At about 2:19 p.m. EST (1919 GMT) today, the craft and comet will pass just 186 miles (300 kilometers) from each other at a relative speed of 13,650 miles per hour (22,000 kph). Controllers on Earth will be monitoring the event, but it takes over 20 minutes for a signal to travel the 242 million miles (389 million kilometers) from Stardust.

There is no doubt that the encounter is dangerous, NASA officials acknowledge.

"In order to collect these particles, we have to put our spacecraft in harm's way. We have to fly through the coma of Wild 2. This is a tremendously severe environment," said Tom Duxbury, the Stardust project manager.

"This is leading-edge planetary exploration where we have an extreme, severe environment when we go through a storm of dust particles at over six times the speed of a bullet.

"We have done all of the homework, we have done all of our designs and testing on the ground, we have practiced for five years. So even though there is risk, and with planetary exploration we know there aren't any guarantees, we have done everything possible to prepare for our encounter."

If all goes well, the spacecraft will successfully emerge from the comet's dust and gas cloud with its priceless cargo. Stardust's trek ends in January 2006 with the comet samples landing back on Earth inside a protective capsule.

We will be providing live updates on this page during and after today's comet encounter.

THURSDAY, JANUARY 1, 2004

The Stardust spacecraft is moving ever closer to tomorrow's dramatic flyby of Comet Wild 2 when it will collect samples for return to Earth.

"Just like in Star Trek we have our shields up," says Tom Duxbury, the Stardust project manager at the Jet Propulsion Laboratory. "The spacecraft has entered Wild 2's coma, which means at any time we could run into a cometary particle. At 6.1 kilometers per second (approximately 3.8 miles per second), this is no small event."

The comet's coma is a vast cloud of dust and gas surrounding the icy heart of Wild 2.

In an effort to provide shielding for the spacecraft as it barrels through the hazardous cometary environmental, Stardust is fitted with so-called Whipple Shields.

"These take the brunt of all the impacts," Duxbury says. "This is designed and tested to protect the spacecraft during the most critical time during close approach when it is getting hit hundreds of thousands of times a second by these impacting particles."

Named for Dr. Fred L. Whipple, an American astronomer Dr. Fred L. Whipple who in 1950 accurately predicted the "dirty snowball" model of the cometary nucleus as a mixture of dark organic material, rocky grains and water ice. Whipple came up with the idea of safeguarding spacecraft from high-speed collisions of the bits and pieces that are ejected from comets as they circle the Sun.

The shields are two "bumpers" at the front of the spacecraft to protect the solar panels and another protecting the main body of the spacecraft. Each shields is built around composite panels designed to disperse particles as they impact, along with blankets of a ceramic cloth called Nextel that further dissipate and spread particle debris.

TUESDAY, DECEMBER 30, 2003

On a daring first-of-its-kind quest, an armored space probe will race past a three-mile-wide comet Friday to collect samples of the ancient relic that serves as a frozen time capsule from the formation of our solar system.

NASA's Stardust spacecraft was launched in February 1999 on a seven-year, three-billion mile round-trip voyage to Comet Wild 2. After Friday's close encounter, the craft will head for home where a capsule containing tiny bits of the comet's heart will parachute to Earth in 2006.

"This could prove to be a pivotal time for science, a remarkable opportunity to gather evidence that might actually tell us how the planets formed and give us clues about how life on Earth began," said Donald Brownlee, a University of Washington astronomer and chief investigator for the Stardust mission.

"In recent decades, spacecraft have passed fairly close to comets and provided us with excellent data. Stardust, however, marks the first time that we have ever collected samples from a comet and brought them back to Earth for study."

With its arm extended to hold a tennis-racket-like collector into the cloud of gas and dust shrouding Wild 2's icy nucleus, the 16-foot-long Stardust probe will rendezvous with the comet after 2 p.m. EST (1900 GMT) at a distance of 186 miles. The two objects will pass at a relative speed of 13,650 miles per hour.

The collector uses an exotic material, called aerogel, to trap the cometary particles -- impacting at speeds over five times that of a rifle bullet -- without damaging the precious cargo for scientists to analyze on Earth. Aerogel is 99.9 percent air and 0.1 percent silica dioxide. One thousand times less dense than glass, aerogel is like "solid smoke."

"The samples we will collect are extremely small, 10 to 300 microns in diameter, and can only be adequately studied in laboratories with sophisticated analytical instruments," said Brownlee. "Even if a ton of sample were returned, the main information in the solids would still be recorded at the micron level, and the analyses would still be done a single grain at a time."

The collector will be stowed inside a 100-pound descent module that separates from the main body of Stardust to make a fiery plunge into Earth's atmosphere and a parachute-aided touchdown at the U.S. Air Force's Utah Test and Training Range on January 15, 2006. From there, the capsule will be taken to the planetary material curatorial facility at NASA's Johnson Space Center in Houston to begin the much-anticipated examination of the samples.

Scientists are keenly interested in comets because they hold the chemical records from a time billions of years ago when the planets were forming.

"This gives us a real opportunity to find out if our long-held suspicions are right, that comets played a major role in the origin of life," Brownlee said. "No one really knows how life began, but we're certain that carbon was key to the process. Comets are the most carbon-rich materials in the solar system, and we know they are full of organic compounds that fall on the Earth all the time."

Comet Wild 2 (pronounced Vilt 2) was discovered in 1978. The comet's solar orbit extended from Jupiter to beyond Uranus before 1974. But then, Jupiter's gravity altered Wild 2's course, bringing it just beyond the orbit of Mars. It now orbits the Sun once every 6.39 years.

Since it only recently began orbiting close to the Sun, scientists believe our star's heat hasn't had enough time to damage the frozen evidence preserved inside the comet for billions of years while lurking in deep space.

Here is a look at Friday's encounter timeline in Eastern Standard Time. All times are listed as they will happen at the spacecraft. Signals confirming each event will take an additional 20 minutes or so to reach Earth.

• 8:49 a.m.: "Encounter sequence" of onboard computer commands begins
  
  
• 9:19 a.m.: Cometary and interstellar dust analyzer instrument configured
  
  
• 12:19 p.m.: Navigation camera takes approach image
  
  
• 1:19 p.m.: Navigation camera takes approach image
  
  
• 2:04 p.m.: Dust flux monitor instrument turned on
  
  
• 2:12 p.m.: Stops sending data, transmits carrier signal only
  
  
• 2:13 p.m.: Final roll maneuver to adjust encounter orientation or "attitude"
  
  
• 2:19 p.m.: Closest approach to comet
  
  
• 2:25 p.m.: Navigation camera ends period of highest frequency imaging
  
  
• 2:25 p.m.: Roll maneuver to take spacecraft out of encounter orientation
  
  
• 2:26 p.m.: Resumes sending data instead of carrier signal
  
  
• 2:27 p.m.: Navigation camera takes final picture
  
  
• 2:29 p.m.: Navigation camera turned off
  
  
• 2:36 p.m.: Begins transmitting images, dust flux monitor data