JPL: Stardust Prepares for Valentine's Day Comet Rendezvous

[bystander]

Stardust-NExT Prepares for Valentine's Day Comet Rendezvous
NASA JPL-Caltech Stardust-NExT | 2011 Jan 19

Artist rendering of Stardust-NExT spacecraft. [i](Credit: NASA/JPL)[/i]

---

NASA's Stardust-NExT spacecraft is nearing a celestial date with comet Tempel 1 at approximately 8:37 p.m. PST (11:37 p.m. EST), on Feb. 14. The mission will allow scientists for the first time to look for changes on a comet's surface that occurred following an orbit around the sun.

The Stardust-NExT, or New Exploration of Tempel, spacecraft will take high-resolution images during the encounter, and attempt to measure the composition, distribution, and flux of dust emitted into the coma, or material surrounding the comet's nucleus. Data from the mission will provide important new information on how Jupiter-family comets evolved and formed.

The mission will expand the investigation of the comet initiated by NASA's Deep Impact mission. In July 2005, the Deep Impact spacecraft delivered an impactor to the surface of Tempel 1 to study its composition. The Stardust spacecraft may capture an image of the crater created by the impactor. This would be an added bonus to the huge amount of data that mission scientists expect to obtain.

"Every day we are getting closer and closer and more and more excited about answering some fundamental questions about comets," said Joe Veverka, Stardust-NExT principal investigator at Cornell University, Ithaca, N.Y. "Going back for another look at Tempel 1 will provide new insights on how comets work and how they were put together four-and-a-half billion years ago."

At approximately 336 million kilometers (209 million miles) away from Earth, Stardust-NExT will be almost on the exact opposite side of the solar system at the time of the encounter. During the flyby, the spacecraft will take 72 images and store them in an onboard computer.

Initial raw images from the flyby will be sent to Earth for processing that will begin at approximately midnight PST (3 a.m. EST) on Feb. 15. Images are expected to be available at approximately 1:30 a.m. PST (4:30 a.m. EST).

As of today, the spacecraft is approximately 24.6 million kilometers (15.3 million miles) away from its encounter. Since 2007, Stardust-NExT executed eight flight path correction maneuvers, logged four circuits around the sun and used one Earth gravity assist to meet up with Tempel 1.

Another three maneuvers are planned to refine the spacecraft's path to the comet. Tempel 1's orbit takes it as close in to the sun as the orbit of Mars and almost as far away as the orbit of Jupiter. The spacecraft is expected to fly past the nearly 6-kilometer-wide comet (3.7 miles) at a distance of approximately 200 kilometers (124 miles).

In 2004, the Stardust mission became the first to collect particles directly from comet Wild 2, as well as interstellar dust. Samples were returned in 2006 for study via a capsule that detached from the spacecraft and parachuted to the ground southwest of Salt Lake City. Mission controllers placed the still viable Stardust spacecraft on a trajectory that could potentially reuse the flight system if a target of opportunity presented itself.

In January 2007, NASA re-christened the mission Stardust-NExT and began a four-and-a-half year journey to comet Tempel 1.

"You could say our spacecraft is a seasoned veteran of cometary campaigns," said Tim Larson, project manager for Stardust-NExT at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's been half-way to Jupiter, executed picture-perfect flybys of an asteroid and a comet, collected cometary material for return to Earth, then headed back out into the void again, where we asked it to go head-to-head with a second comet nucleus."

The mission team expects this flyby to write the final chapter of the spacecraft's success-filled story. The spacecraft is nearly out of fuel as it approaches 12 years of space travel, logging almost 6 billion kilometers (3.7 billion miles) since launch in 1999. This flyby and planned post-encounter imaging are expected to consume the remaining fuel.

Stardust-NExT Mission

[bystander]

NASA Comet Hunter Spots Its Valentine
NASA JPL-Caltech Stardust-NExT | DC Agle | 211 Jan 27

The first image of comet Tempel 1 taken by NASA's Stardust spacecraft is a composite made from observations on Jan. 18 and 19, 2011. On Valentine's Day (Feb. 14 in U.S. time zones), Stardust will fly within about 200 kilometers (124 miles) of the comet's nucleus. [i](Image credit: NASA/JPL-Caltech)[/i]

---

NASA's Stardust spacecraft has downlinked its first images of comet Tempel 1, the target of a flyby planned for Valentine's Day, Feb. 14. The images were taken on Jan. 18 and 19 from a distance of 26.3 million kilometers (16.3 million miles), and 25.4 million kilometers (15.8 million miles) respectively. On Feb. 14, Stardust will fly within about 200 kilometers (124 miles) of the comet's nucleus.

"This is the first of many images to come of comet Tempel 1," said Joe Veverka, principal investigator of NASA's Stardust-NExT mission from Cornell University, Ithaca, N.Y. "Encountering something as small and fast as a comet in the vastness of space is always a challenge, but we are very pleased with how things are setting up for our Valentine's Day flyby."

The composite image is a combination of several images taken by Stardust's navigation camera. Future images will be used to help mission navigators refine Stardust's trajectory, or flight path, as it closes the distance between comet and spacecraft at a rate of about 950,000 kilometers (590,000 miles) a day. On the night of encounter, the navigation camera will be used to acquire 72 high-resolution images of the comet's surface features. Stardust-NExT mission scientists will use these images to see how surface features on comet Tempel 1 have changed over the past five-and-a-half years. (Tempel 1 had previously been visited and imaged in July of 2005 by NASA's Deep Impact mission).

Launched on Feb. 7, 1999, Stardust became the first spacecraft in history to collect samples from a comet (comet Wild 2), and return them to Earth for study. While its sample return capsule parachuted to Earth in January 2006, mission controllers were placing the still-viable spacecraft on a path that would allow NASA the opportunity to re-use the already-proven flight system if a target of opportunity presented itself. In January 2007, NASA re-christened the mission "Stardust-NExT" (New Exploration of Tempel), and the Stardust team began a four-and-a-half year journey for the spacecraft to comet Tempel 1. This will be the second exploration of Tempel 1 by a spacecraft (Deep Impact).

Along with the high-resolution images of the comet's surface, Stardust-NExT will also measure the composition, size distribution and flux of dust emitted into the coma, and provide important new information on how Jupiter-family comets evolve and how they formed 4.6 billion years ago.

Stardust-NExT

[bystander]

Spacecraft and comet fated for Valentine's Day rendezvous
Cornell University | Lauren Gold | 2011 Feb 08

The Stardust spacecraft would be redirected to pass within 200 kilometers of comet Tempel 1 in February 2011 -- close enough to provide a first look at the crater caused by the Deep Impact collision (bull's eye) and a large piece of previously unmapped territory (blue). [i](Credit: NASA/JPL/Cornell)[/i]

---

In the beginning, both couples seemed meant for each other.

There was the Stardust spacecraft, launched in 1999, and her cometary fiancée, Wild 2. Betrothed from afar, the two headed blissfully toward a 2004 rendezvous.

Meanwhile, the comet Tempel 1, making her own solitary way around the sun in 2005, was heading toward a more explosive relationship with the Deep Impact spacecraft.

But alas, heavenly though the matches were -- and fruitful, with each yielding valuable information about the evolution of the solar system -- neither lasted. In 2006, Stardust tossed her dusty tokens of Wild 2 down to Earth for analysis and vowed to start anew. She was a little older now; but with all her parts in good working order and adequate fuel, she was ready for a second mission. And Tempel 1, scarred by her violent encounter with Deep Impact, was looking for a kinder, gentler match.

On Valentine's Day, the two will meet. In the heat of the moment, astronomers hope, Tempel 1 will be cajoled into yielding a few more clues about her background. And Stardust, equipped with imaging and dust composition analysis instruments, will relay those clues to Earth.

The expectant matchmakers

Among the astronomers waiting patiently are Joe Veverka, professor of astronomy and principal investigator for Stardust-NExT, the NASA mission orchestrating the rendezvous.

The Valentine's Day flyby could yield a wealth of new information about Tempel 1's structure and composition, Veverka said, and how its features change with every passage around the sun.

"We know that comets lose material," he said in a recent press conference; "But the question is 'How does the surface change, and where does the surface change?'" Comparing the 2005 images with the new ones -- taken one rotation around the sun later -- could provide the answer.

Stardust could also catch a glimpse of the crater that formed when a probe from Deep Impact crashed into Tempel 1's surface six years ago.

"That impact threw up so much ejecta that Deep Impact never saw the crater," Veverka said. "So it could never see how big the crater is and what [it] tells us about the mechanical properties of the surface."

That information is vital for any future mission that involves landing a spacecraft on the surface of a comet, he said.

And finally, astronomers hope the rendezvous will provide a closer look at some of the surface features Deep Impact saw when it zoomed by in 2005. Layered terrain, for example, could contain information about how comet nuclei were formed; and smooth flows hint at some internal processes that could be working their way up to change the surface.

"Deep Impact saw only about one-third of the surface," Veverka said. "We would like to see more."

So -- as Feb. 14 approaches and other romantic souls plan candlelight dinners, Veverka and colleagues are tracking the pair, now hurtling toward each other at about 590,000 miles a day.

Stardust caught its first glimpse of Tempel 1 Jan. 26. It will keep its eye on the comet as it approaches, collecting data to help mission navigators refine its trajectory.

Close encounter

And on Valentine's Day, as Earthbound lovers gaze into each other's eyes, the two orbiting bodies will meet, about 120 miles apart. As they pass, Stardust will test the density and composition of the dust surrounding the comet and snap 72 high-resolution images.

Researchers expect to receive the data within a few hours of the closest encounter. "The science team is awfully excited," Veverka said.

And thus, perhaps, the curtain will close on this cometary encore. But as with all concluded affairs, there will be months -- perhaps years -- of data analysis; and ultimately, plans for the next mission.

"Comets preserve some of the most faithful information about what happened when the solar system formed," Veverka said. "This is a step toward the ultimate answer."

[bystander]

Stardust Spacecraft Completes Comet Flyby
NASA JPL-Caltech | DC Agle | 2011 Feb 14

Mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., watched as data downlinked from the Stardust spacecraft indicated it completed its closest approach with comet Tempel 1. An hour after closest approach, the spacecraft turned to point its large, high-gain antenna at Earth. It is expected that images of the comet's nucleus collected during the flyby will be received on Earth starting at about midnight California time (3 a.m. EST on Tuesday, Feb. 15).

Preliminary data already transmitted from the spacecraft indicate the time of closest approach was about 8:39 p.m. PST (11:39 p.m. EST), at a distance of 181 kilometers (112 miles) from Tempel 1.

This is a bonus mission for the comet chaser, which previously flew past comet Wild 2 and returned samples from its coma to Earth. During this bonus encounter, the plan called for the spacecraft to take images of the comet's surface to observe what changes occurred since a NASA spacecraft last visited. (NASA's Deep Impact spacecraft executed an encounter with Tempel 1 in July 2005).

Stardust-NExT is a low-cost mission that will expand the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology in Pasadena, manages Stardust-NExT for NASA's Science Mission Directorate, Washington, D.C. Lockheed Martin Space Systems, Denver, built the spacecraft and manages day-to-day mission operations.

http://stardustnext.jpl.nasa.gov/
http://www.nasa.gov/stardust/

Comet Hunter's First Images on the Ground
NASA JPL-Caltech | DC Agle | 2011 Feb 15

---

Mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., have begun receiving the first of 72 anticipated images of comet Tempel 1 taken by NASA's Stardust spacecraft.

... images are available at http://www.jpl.nasa.gov/news/stardust/ and http://www.nasa.gov/mission_pages/stard ... index.html. Additional images, including those from closest approach, are being downlinked in chronological order and will be available later in the day.

A news conference previously planned for 10 a.m. PST (1 p.m. EST) will be held later in the day, to allow scientists more time to analyze the data and images. A new time will be announced later this morning.

[bystander]

NASA Releases Images of Man-Made Crater on Comet
NASA JPL-Caltech | DC Agle | 2011 Feb 15

[url=http://www.nasa.gov/mission_pages/stardust/multimedia/Shultz5-2.html][size=110][b]Comet Tempel 1 Impact Site[/b][/size][/url] [i](Credit: NASA/JPL-Caltech/University of Maryland/Cornell)[/i] [i]Left: Deep Impact - July 2005; Right: Stardust-NExT Feb 2011[/i]

---

NASA's Stardust spacecraft returned new images of a comet showing a scar resulting from the 2005 Deep Impact mission. The images also showed the comet has a fragile and weak nucleus.

The spacecraft made its closest approach to comet Tempel 1 on Monday, Feb. 14, at 8:40 p.m. PST (11:40 p.m. EST) at a distance of approximately 178 kilometers (111 miles). Stardust took 72 high-resolution images of the comet. It also accumulated 468 kilobytes of data about the dust in its coma, the cloud that is a comet's atmosphere. The craft is on its second mission of exploration called Stardust-NExT, having completed its prime mission collecting cometary particles and returning them to Earth in 2006.

The Stardust-NExT mission met its goals, which included observing surface features that changed in areas previously seen during the 2005 Deep Impact mission; imaging new terrain; and viewing the crater generated when the 2005 mission propelled an impactor at the comet.

"This mission is 100 percent successful," said Joe Veverka, Stardust-NExT principal investigator of Cornell University, Ithaca, N.Y. "We saw a lot of new things that we didn't expect, and we'll be working hard to figure out what Tempel 1 is trying to tell us."

Several of the images provide tantalizing clues to the result of the Deep Impact mission's collision with Tempel 1.

"We see a crater with a small mound in the center, and it appears that some of the ejecta went up and came right back down," said Pete Schultz of Brown University, Providence, R.I. "This tells us this cometary nucleus is fragile and weak based on how subdued the crater is we see today."

Engineering telemetry downlinked after closest approach indicates the spacecraft flew through waves of disintegrating cometary particles, including a dozen impacts that penetrated more than one layer of its protective shielding.

"The data indicate Stardust went through something similar to a B-17 bomber flying through flak in World War II," said Don Brownlee, Stardust-NExT co-investigator from the University of Washington in Seattle. "Instead of having a little stream of uniform particles coming out, they apparently came out in chunks and crumbled."

While the Valentine's Day night encounter of Tempel 1 is complete, the spacecraft will continue to look at its latest cometary obsession from afar.

"This spacecraft has logged over 3.5 billion miles since launch, and while its last close encounter is complete, its mission of discovery is not," said Tim Larson, Stardust-NExT project manager at JPL. "We'll continue imaging the comet as long as the science team can gain useful information, and then Stardust will get its well-deserved rest."

[bystander]

Stardust: Good to the Last Drop
NASA JPL-Caltech | 2011 Mar 23

---

On Thursday, March 24, at about 4 p.m. PDT (7 p.m. EDT), NASA's Stardust spacecraft will perform a burn with its main engines.

At first glance, the burn is something of an insignificant event. After all, the venerable spacecraft has executed 40 major flight path maneuvers since its 1999 launch, and between these main engines and the reaction control system, its rocket motors have collectively fired more than 2 million times. But the March 24 burn will be different than all others. This burn will effectively end the life of NASA's most traveled comet hunter.

"We call it a "burn to depletion," and that is pretty much what we're doing - firing our rockets until there is nothing left in the tank," said Stardust-NExT project manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's a unique way for an interplanetary spacecraft to go out. Essentially, Stardust will be providing us useful information to the very end."

Burn to depletion will answer the question about how much fuel Stardust had left in its tank.

"We'll take that data and compare it to what our estimates told us was left," said Allan Cheuvront, Lockheed Martin Space Systems program manager for Stardust-NExT. "That will give us a better idea how valid our fuel consumption models are and make our predictions even more accurate for future missions."

Stardust's burn to depletion is expected to impart valuable information because the spacecraft has been running on borrowed time -- for some time. Launched on Feb. 7, 1999, Stardust had already flown past an asteroid (Annefrank), flown past and collected particle samples from a comet (Wild 2), and returned those particles to Earth in a sample-return capsule in January 2006 - and in so doing racking up 4.63 billion kilometers (2.88 billion miles) on its odometer. NASA then re-tasked the spacecraft to perform a flyby of comet Tempel 1, a bonus mission that would require an additional half decade and 1.04 billion kilometers (646 million miles). With all those milestones and all that time logged up there, the Stardust team knew the end was near. They just didn't know how close.

Prior to this final burn, Stardust will point its medium-gain antenna at Earth - some 312 million kilometers (194 million miles) away. As there is no tomorrow for Stardust, the spacecraft is expected to downlink information on the burn as it happens. The command from the spacecraft computer ordering the rockets to fire will be sent for 45 minutes. The burn is expected to last anywhere between a couple to well above 10 minutes. It is estimated the burn will accelerate the spacecraft anywhere from 2.5 to 35.2 meters per second (6 to 79 mph).

"What we think will happen is that when the fuel reaches a critically low level, gaseous helium will enter the thruster chambers," said Larson. "The resulting thrust will be less than 10 percent of what was expected. While Stardust will continue to command its rocket engines to fire until the pre-planned firing time of 45 minutes has elapsed, the burn is essentially over."

Twenty minutes after the engines run dry, the spacecraft's computer brain will command its transmitters off. They actively shut off their radios to preclude the remote chance that at some point down the road Stardust's transmitter will turn on and broadcast on a frequency being used by operational spacecraft. Turning off the transmitter ensures that there will be no unintended radio interference in the future.

Without fuel to power the spacecraft's attitude control system, Stardust's solar panels will not remain pointed at the sun. When this occurs, the spacecraft's batteries are expected to deplete within hours.

"When we take into account all the possibilities for how long the burn could be and the post-burn trajectories, we project that over the next 100 years, Stardust will not get any closer than 1.7 million miles of Earth's orbit, or within 13 million miles of Mars orbit," said Larson. "That is far enough from protected targets to meet NASA's Planetary Protection objectives. "

Some planetary spacecraft like the Galileo mission to Jupiter are intentionally sent into the planet's atmosphere to make sure they are destroyed in a controlled way. Others have their transmitters shut off or just fade away, said Larson. "I think this is a fitting end for Stardust. It's going down swinging."

Stardust-NExT

[bystander]

NASA Stardust Spacecraft Officially Ends Operations
NASA HQ | 2011 Mar 25

NASA's Stardust spacecraft sent its last transmission to Earth at 7:33 p.m. EDT Thursday, March 24, shortly after depleting fuel and ceasing operations. During an 11-year period, the venerable spacecraft collected and returned comet material to Earth and was reused after the end of its prime mission in 2006 to observe and study another comet during February 2011.

[owlice]

Pelted by comet bits:

Click to play embedded YouTube video.