Comets Archives

February 16, 2011December 24, 2015 by Ken Kremer

NASA’s Stardust Discovers Human made Deep Impact Crater on Comet Tempel 1

Tempel 1, as Seen by Two Spacecraft. These two images show the different views of comet Tempel 1 seen by NASA's Deep Impact spacecraft (left) and NASA's Stardust spacecraft (right). Two craters, about 300 meters (1,000 feet) in diameter, help scientists locate the area hit by the impactor released by Deep Impact in July 2005. The dashed lines correlate the features. Stardust approached the comet from a different angle on Feb. 14, 2011. Credit: NASA/JPL-Caltech/University of Maryland/Cornell

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NASA’s aging and amazing Stardust space probe has at last discovered the human made crater created on Comet Tempel 1 in 2005 by the history making cosmic smash up with NASA’s Deep Impact penetrator. Stardust streaked past the comet on Feb. 14 at 10.9 km/sec, or 24,000 MPH, and succeeded in briefly photographing the crater as it approached within 178 km (111 mi) during the fleeting moments of the probes closest approach.

The intentional celestial collision in 2005 was designed to violently unleash the buried remnants of the early solar system into an enormous ejecta cloud of dusty debris that scientists could sift for clues to help unlock the secrets of how we all formed and evolved some 4.5 Billion Years ago.

Tempel 1 is the first comet to receive a second visit by probes from Earth.

Comets have continuously smashed into Earth over the eons and delivered vast quantities of key ingredients – such as water and organic molecules – that may have sparked the formation of life on the early Earth.

NASA approved the use of the already orbiting Stardust-NExT spacecraft to follow up on the science discoveries by Deep Impact as the best and most economical way to try and locate the crater blast site, image new terrain and look for changes on the comets surface since the 2005 mission as the comet also completed another orbit around our Sun and eroded due to solar heating.

The human made crater is about 150 meters wide and was formed by a 375 kilogram (800 pound) projectile propelled into the speeding path of Comet Tempel 1 by the Deep Impact mothership in 2005.

Tempel 1 Impact Site.
This pair of images shows the before-and-after comparison of the part of comet Tempel 1 that was hit by the impactor from NASA's Deep Impact spacecraft. The left-hand image is a composite made from images obtained by Deep Impact in July 2005. The right-hand image shows arrows identifying the rim of the crater caused by the impactor. The crater is estimated to be 150 meters (500 feet) in diameter. This image also shows a brighter mound in the center of the crater likely created when material from the impact fell back into the crater. Credit: NASA/JPL-Caltech/University of Maryland/Cornell

Stardust-NExT took 72 high resolution science images of the comet during the Valentine’s Day encounter flyby on Feb, 14 at 11:40 p.m. EST (8:40 p.m. PST). The probe absolutely had to be precisely navigated to exactly hit the aim point for sequencing the images to match the right moment in the erratic rotation of the volatile comet.

The results of the Stardust-NExT mission were announced at a post encounter new briefing after most of the images and science data had streamed back to Earth. The science team and NASA said that all the mission objectives were accomplished.

“If you ask me was this mission 100 percent successful in terms of the science, I’d have to say no. It was 1000 percent successful!” said Stardust-NExT principal investigator Joe Veverka of Cornell University, Ithaca, N.Y., at the news briefing.

“We found the Deep Impact crater. We see erosion in comparison to 2005. So we do see changes. Erosion on the scale of 20 to 30 meters of material has occurred in the five or six years since we took the first picture. We are seeing a change, but we have to spend time quantifying the changes and understanding what they mean.”

“We saw a lot of new territory. It’s amazing with lots of layers. There is lots of surface sublimation. We had to arrive at precisely the right time in order to see new and old territory.”

“We had monitored the comets rotation for several years. And we got the longitude almost perfect within 1 or 2 degrees,” Veverka said.

Tempel 1 Impact Site
Credit: NASA/JPL-Caltech/University of Maryland/Cornell

It took a few years of careful study to deduce the comets complex rotational patterns which change as the body orbits in a wide orbital path between Mars and Jupiter and is heated by the sun.

Peter Schultz, a science team co-investigator agreed and showed the comparison images.

“We saw the crater,” said Schultz, of University. “It’s subdued; it’s about 150 meters across and has a small central mound in the center. It looks as if from the impact, the stuff went up and came back down. So we did get it, there’s no doubt. I think one of the bottom-line messages is that this surface of the comet where we hit is very weak. It’s fragile. So the crater partly healed itself.”

“It was about the size we expected. But more subdued.”

The probes mission is almost complete since it has very little fuel left. The remaining science data from the flyby is being sent back and some outbound data is being collected.

“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.”

Stardust-NExT is a repurposed spacecraft that has journeyed nearly 6 billion kilometers since it was launched in 1999.

Initially christened as Stardust, the spaceships original task was to fly by Comet Wild 2 in 2004. It also collected priceless cometary dust particles from the coma which was safely parachuted back to Earth inside a return canister in 2006. High powered science analysis of the precious comet dust will help researchers discern the origin and evolution of our solar system.

This was humanities first revisit to a comet and at a bargain basement price by using an old spacecraft already in space.

“The cost was just $29 Million dollars. A new Discovery class mission costs $300 to 500 Million. So that’s maybe 6% the cost of developing and launching a new mission,” said Ed Weiler, the associate administrator for NASA’s Science Mission Directorate at NASA HQ in Washington, DC.

Read more about the Stardust-NExT Flyby and mission in my earlier stories here, here, here and here

Changes to Smooth Terrain (Annotated)
This image layout depicts changes in the surface of comet Tempel 1, observed first by NASA's Deep Impact Mission in 2005 (top right) and again by NASA's Stardust-NExT mission on Feb. 14, 2011 (bottom right). Between the two visits, the comet made one trip around the sun. The image at top left is a wider shot from Deep Impact. The smooth terrain is at a higher elevation than the more textured surface around it. Scientists think that cliffs, illustrated with yellow lines to the right, are being eroded back to the left in this view. The cliffs appear to have eroded as much as 20 to 30 meters (66 to 100 feet) in some places, since Deep Impact took the initial image. The box shows depressions that have merged together over time, also from erosion. This erosion is caused by volatile substances evaporating away from the comet. Credit: NASA/JPL-Caltech/University of Maryland/Cornell

February 15, 2011December 24, 2015 by Ken Kremer

Stardust-NExT Unveils Astoundingly Detailed and Crater-rich Photos of Comet Tempel 1

NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:38 p.m. PST (11:38 p.m. EST) on Feb 14, 2011. The comet was first visited by NASA's Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/Cornell.

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NASA’s Stardust-NExT raced past Comet Tempel 1 overnight Feb 14/15 at over 10 km/sec or 24,000 MPH and is now sending back the 72 astoundingly detailed and crisp science images of Comet Tempel 1 taken during closest approach at 11:37 p.m. EST on Feb. 14.

The high resolution images are amazingly sharp and clearly show a pockmarked and crater rich terrain of both new and previously unseen territory on the icy comets surface. The Stardust-NExT comet chaser zoomed within 181 km (112 miles) of the nucleus of the volatile comet.

See the photo gallery above and below, which is being updated as the images come back. I am enhancing and brightening certain images to show further details. The new images of Tempel 1 from Stardust-NExT surpass my expectations and look even sharper then those taken by NASA’s Deep Impact comet smasher in July 2005.

Read more about the Stardust-NExT Flyby and mission in my earlier stories here, here and here

NASA news briefing on Stardust-NExT at 3:30 p.m Feb 15 live on NASA TV

Update: Read my follow up story on the discovery of the Deep Impact crater here

Photo gallery of Comet Tempel 1 images from NASA’s Stardust-NExT comet mission on Feb 14, 2011

NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:39 p.m. PST (11:39 p.m. EST) on Feb 14, 2011. The comet was first visited by NASA's Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/Cornell.
Image brightened and enhanced to show additional detail.

Images brightened and enhanced to show additional detail by Ken Kremer

February 15, 2011December 24, 2015 by Ken Kremer

Stardust-NExT zooms by Comet Tempel 1 for Cosmic Encounter

Comet Tempel 1 imaged by NASA's Stardust on Feb 14, Valentine’s Day. NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:38 p.m. PST (11:38 p.m. EST) on Feb 14, 2011. . The comet was first visited by NASA's Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/Cornell **Update Feb 15**: Beautifully sharp Comet images now being downlinked. New story upcoming.

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NASA’s Stardust-NExT comet chaser successfully zoomed by Comet Temple 1 exactly as planned a short while ago at 11:37 p.m. EST on Feb. 14.

The cosmic Valentine’s Day encounter between the icy comet and the aging probe went off without a hitch. Stardust snapped 72 science images as it raced by at over 10 km/sec or 24,000 MPH and they are all centered in the cameras field of view. The probe came within 181 km (112 miles) of the nucleus of the volatile comet.

The images are being transmitted back now and it will take a several hours until the highest resolution images are available for the science team and the public to see. The first few images from a distance of over a thousand miles can be seen here

Tempel 1 is the first comet to be visited twice by spaceships from Earth. The primary goal was to find out how much the comet has changed in the five years since she was last visited by NASA’s Deep Impact mission in 2005, says Joe Ververka of Cornell University, who is the principal investigator of the Stardust-NExT mission. Deep Impact delivered a 375 kg projectile which blasted the comet and created an impact crater and an enormous cloud of dust so that scientists could study the composition and interior of the comet.

“We are going to be seeing the comet just after its closest passage to the sun. We know the comet is changing because the ice melts. We hope to see old and new territory and the crater and complete the Deep Impact experiment.”

Stardust-NExT is a repurposed spacecraft. Initially christened as Stardust, the spaceships original task was to fly by Comet Wild 2 in 2004. It also collected priceless cometary dust particles from the coma which were safely parachuted back to Earth inside a return canister in 2006. High powered science analysis of the precious comet dust will help researchers discern the origin and evolution of our solar system.

Stardust-NExt approaching Comet Tempel 1.
Artist concept of NASA's Stardust-NExT mission, which will fly by Comet Tempel 1 on Feb. 14, 2011. Credit: NASA/JPL-Caltech/LMSS

Stardust was hurriedly snapping high resolution pictures every 6 seconds and collecting data on the dust environment during the period of closest approach which lasted just about 8 minutes. The anticipation was building after 12 years of hard work and a journey of some 6 Billion kilometers (3.5 Billion miles)

“The Stardust spacecraft did a fantastic job,” says Tim Larson, the Stardust-NExT mission project manager from the Jet Propulsion Laboratory (JPL), Pasadena, Calif. “Stardust has already flown past a asteroid and a comet and returned comet particles to Earth”

“Because of the flyby geometry the antenna was pointed away from earth during the encounter. Therefore all the science images and data was stored in computer memory on board until the spacecraft was rotated to point towards Earth about an hour after the flyby.”

Each image takes about 15 minutes to be transmitted back to Earth by the High Gain Antenna at a data rate of 15,800 bits per second and across about 300 million miles of space.

NASA had bracketed five special images from the closest range as the first ones to be sent back. Instead, the more distant images were sent first. It will take about 10 hours to receive all the images.

So everyone had to wait a few hours longer to see the fruit of their long labor. Most of the team from NASA, JPL and Lockheed Martin has been working on the mission for a dozen years since its inception.

“We had a great spacecraft and a great team,” says Ververka. “Apparently, everything worked perfectly. The hardest thing now is we have to wait a couple of hours before we see all the goodies stored on board.”

The entire flyby was carried out autonomously using a preprogrammed sequence of commands. Due to the vast distance from Earth there was no possibility for mission controllers to intervene in real time.

Confirmation of a successful fly by and science imaging was not received until about 20 minutes after the actual event at about 11:58 p.m. EST. The dust flux monitor also registered increased activity just as occurred during the earlier Stardust flyby of Comet Wild 2 in 2004.

The Stardust-NExT science briefing on NASA TV will be delayed a few hours, until perhaps about 4 p.m. EST

Check back here later at Universe Today, on Tuesday, Feb. 15 for continuing coverage of the Valentine’s Day encounter of Stardust-NExT with the icy, unpredictable and fascinating Comet Tempel 1

Comet Tempel 1 imaged by NASA's Stardust on Feb 14, Valentine’s Day.
NASA's Stardust-NExT mission took this image of comet Tempel 1 at 8:36 p.m. PST (11:36 p.m. EST) on Feb 14, 2011, from a distance of approximately 2200 km (1360 miles). The comet was first visited by NASA's Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/Cornell

Stardust-NExT Spacecraft & Comet Tempel 1.
Artist rendering of upcoming flyby on February, 14, 2011. Credit: NASA

Stardust-NExT: 2 Comet Flybys with 1 Spacecraft.
Stardust-NExT made history on Valentine’s Day - February, 14, 2011 – Tempel 1 is the first comet to be visited twice by spacrecraft from Earth. Stardust has now successfully visited 2 comets and gathered science data: Comet Wild 2 in 2004 (left) and Comet Tempel 1 in 2011 (right). Artist renderings Credit: NASA. Collage: Ken Kremer.

February 13, 2011December 24, 2015 by Ken Kremer

Romantic Valentines Day Encounter Looms with Icy Comet

NASA's Romantic Rendezvous in space on Valentine’s Day - Feb. 14. The planned Valentine's Day (Feb. 14, 2011) rendezvous between NASA's Stardust-NExT mission and Comet Tempel 1 inspired this chocolate-themed artist's concept. Credit: NASA/JPL-Caltech. Video and graphics below illustrate the icy encounter and animate the flyby trajectory. NASA TV: Live Coverage listed below. Update: See below the latest navigation camera images taken on Feb. 11 – newly obtained from JPL. These images are crucial for precisely aiming Stardust-NExT

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At last, NASA embraces a romantic rendezvous in the dark void of deep space.

And soon the whole world can watch the up close meet up of the hot Stardust probe and the volatile, icy comet. The historic space tryst is less than a day away!

The Stardust-NExT spacecraft successfully hot fired its thrusters for the final course correction maneuver (TCM-33) on Feb. 12, setting up the fleeting celestial encounter with Comet Tempel 1 on Valentine’s Day, Feb. 14, Monday, at 11:37 p.m. EST. The space science probe will fly by the speeding comet at a distance of approximately 200 kilometers (124 miles) and at a speed of 10 km/sec.

Naturally, the fleeing comet is icy, unpredictable and exploding with jets of gas and dust particles. So there is some uncertainly at NASA and amongst the science team as to what we’ll actually see when the cameras unveil the hidden secrets of the nucleus of Temple 1.

The encounter phase has begun now (Feb. 13) at 24 hours prior to closest approach (Feb. 14) and concludes 24 hours after closest approach.

“The final TCM burn on Feb. 12 went well,” JPL spokesman DC Agle told me today (Feb.13)

It’s been a long wait and a far flung journey. Stardust has cruised some 6 Billion kilometers through our solar system – looping several times around the sun over a dozen years and is now nearly bereft of fuel.

For three and a half long years, the anticipation has been building since NASA approved the repurposing of the Stardust spacecraft in 2007 and fired the thrusters to alter the probes trajectory to Comet Temple 1 for this bonus extended mission.

But until the photos are transmitted across 300 million kilometers of space back to Earth, we won’t know which face of the comets surface was turned towards the camera as the curtain pulls back for the revealing glimpse.

Everything hinges on how accurately the mission team aims the reliable probe and the finicky rotation of the changeable comet.

The irregularly shaped nucleus of Tempel 1 measures barely 5 to 8 km in diameter.

Stardust-NExT: 2 Comet Flybys with 1 Spacecraft.
Stardust-NExT makes history on Valentine’s Day - February, 14, 2011
Tempel 1 is the first comet to be visited twice by spacecraft from Earth. Stardust will have visited 2 comets and gathered science data: Comet Wild 2 in 2004 (left) and Comet Tempel 1 in 2011 (right).
Artist renderings Credit: NASA. Collage: Ken Kremer.

The Feb. 14 encounter marks the first time in history that a comet has been visited twice by spaceships from Earth. The revisit provides the first opportunity for up-close observations of a comet both before and after a single orbital pass around the sun.

In July 2005, NASA’s Deep Impact probe delivered a 375 kg projectile that penetrated at high speed directly into the comets nucleus. The blast created an impact crater and ejected an enormous cloud of debris that was studied by the Deep Impact spacecraft as well as an armada of orbiting and ground based telescopes.

Somewhat unexpectedly, the new crater was totally obscured from the cameras view by light reflecting off the dust cloud.

“The primary goal is to find out how much the comet’s surface has changed between two close passages to the sun since it was last visited in 2005,” says Joe Ververka of Cornell University, who is the principal investigator of the Stardust-NExT mission.

This time around, researchers hope to determine the size of the crater. Numerous bets hinge on that determination.

It’s also quite possible that the crater itself has significantly changed in the intervening five and one half years as the Jupiter-class comet orbits between Mars and Jupiter.

“Comets rarely behave,” says Tim Larson, the Stardust-NExT mission project manager from the Jet Propulsion Laboratory (JPL), Pasadena, Calif.

“Temple 1 exhibits a complex rotation. The rotation period is about 41 hours. But the trajectory changes due to the comet jets and activity.”

“Ideally we would like to obtain photos of old and new territory and the crater from the Deep Impact encounter in 2005,” Larson explained.

“Tempel 1 is the most observed comet in history using telescopes worldwide as well as the Hubble and Spitzer Space Telescopes.”

Engineers are using all this data to fine tune the aim of the craft and get a handle on which sides of the comet will be imaged. But either way the team will be elated with the science results regardless of whether the images reveal previously seen or new terrain.

Today, Feb. 13, mission controllers at JPL are uplinking the final flyby sequences and parameters for Monday’s (Feb. 14) historic encounter.

Stardust-NExT will take 72 high resolution images of Comet Tempel 1 during the close approach. The team expects the nucleus to be resolved in several of the closest images. These will be stored in an onboard computer and relayed back to Earth starting about three hours later.

“All data from the flyby (including the images and science data obtained by the spacecraft’s two onboard dust experiments) are expected to take about 10 hours to reach the ground,” according to a NASA statement.

3 D stereo view of Comet Wild 2 from Stardust flyby in 2004. Credit: NASA/

Stardust-NExT is a repurposed spacecraft and this will be the last hurrah for the aging probe. Stardust was originally launched way back in 1999 and accomplished its original goal of flying through a dust cloud surrounding the nucleus of Comet Wild 2 on Jan. 2, 2004. During the flyby, the probe also collected comet particles which were successfully returned to Earth aboard a sample return capsule which landed in the Utah desert in January 2006.

Stardust continued its solitary voyage through the void of the space. Until now !

Watch the Stardust-NExT Romantic Rendezvous: Live on NASA TV

NASA has scheduled live mission commentary of the flyby and a post encounter news briefing on Feb. 14 and Feb. 15. These will be televised on NASA TV as follows:

February 14, Monday
11:30 p.m. – 1 a.m. (Feb. 15) – Live Stardust-NExT Mission Commentary (including coverage of closest approach to Comet Tempel 1 and re-establishment of contact with the spacecraft following the encounter) – JPL

February 15, Tuesday
3 – 4:30 a.m. Live Stardust-NExT Mission Commentary (resumes with the arrival of the first close-approach images of Comet Tempel 1) – JPL

1 p.m. – Stardust-NExT Post-Encounter News Briefing – JPL

Five facts you should know about NASA’s Stardust-NExT spacecraft as it prepares for a Valentine’s “date” with comet Tempel 1. From a NASA Press Release

1. “The Way You Look Tonight” – The spacecraft is on a course to fly by comet Tempel 1 on Feb. 14 at about 8:37 p.m. PST (11:37 p.m. EST) — Valentine’s Day. Time of closest approach to Tempel 1 is significant because of the comet’s rotation. We won’t know until images are returned which face the comet has shown to the camera.

Stardust- Earth return capsule with cometary dust particles in 2006. Credit: NASA/JPL

2. “It’s All Coming Back To Me Now” – In 2004, Stardust became the first mission to collect particles directly from a comet, Wild 2, as well as samples of interstellar dust. The samples were returned in 2006 via a capsule that detached from the spacecraft and parachuted to the ground at a targeted area in Utah. Mission controllers then placed the still-viable Stardust spacecraft on a flight path that could reuse the flight system, if a target of opportunity presented itself. Tempel 1 became that target of opportunity.

3. “The First Time Ever I Saw Your Face” – The Stardust-NExT mission will allow scientists for the first time to look for changes on a comet’s surface that occurred after one orbit around the sun. Tempel 1 was observed in 2005 by NASA’s Deep Impact mission, which put an impactor on a collision course with the comet. Stardust-NExT might get a glimpse of the crater left behind, but if not, the comet would provide scientists with previously unseen areas for study. In addition, the Stardust-NExT encounter might reveal changes to Tempel 1 between Deep Impact and Stardust-Next, since the comet has completed an orbit around the sun.

4. “The Wind Beneath My Wings” – This Tempel 1 flyby will write the final chapter of the spacecraft’s success story. The aging spacecraft approached 12 years of space travel on Feb. 7, logging almost 6 billion kilometers (3.5 billion miles) since launch. The spacecraft is nearly out of fuel. The Tempel 1 flyby and return of images are expected to consume the remaining fuel.

5. “Love is Now the Stardust of Yesterday” – Although the spacecraft itself will no longer be active after the flyby, the data collected by the Stardust-NExT mission will provide comet scientists with years of data to study how comets formed and evolved.

Do you know the artists names who wrote and sing these celestially romantic tunes ?

NASA Stardust NExT Video: Date with a Comet – Tempel 1

13 Feb 2011 Position of STARDUST-NExT probe
Looking Down on the Sun. This image shows the current position of the STARDUST spacecraft and the spacecraft's trajectory (in blue) around the Sun. Credit: NASA

Latest navigation camera images of Comet Temple 1 coma and surrounding stars.
Taken by Stardust-NExT at about 10:30 a.m. on Feb. 11 – newly obtained from JPL. This region is about 1.2 degrees on a side - 351 x 351 pixels. Exposure duration 10 seconds. These images are crucial for precisely aiming Stardust-NExT. Credit: NASA/JPL

Enlargement of latest navigation camera image of Comet Temple 1 coma and surrounding stars showing a small section around the comet. Taken by Stardust-NExT at about 10:30 a.m. on Feb. 11 – newly obtained from JPL. Exposure duration 10 seconds. These images are crucial for precisely aiming Stardust-NExT. Credit: NASA/JPL

February 1, 2011December 24, 2015 by Nancy Atkinson

Mission Complete: NEOWISE Concludes Hunt for Near-Earth Objects

During its one-year mission, NASA's Wide-field Infrared Survey Explorer, or WISE, mapped the entire sky in infrared light. Among the multitudes of astronomical bodies that have been discovered by the NEOWISE portion of the WISE mission are 20 comets. Image credit: NASA/JPL-Caltech/UCLA

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The WISE spacecraft has completed a special mission called NEOWISE, looking for small bodies in the solar system, and has discovered a plethora of previously unknown objects. The NEOWISE mission found 20 comets, more than 33,000 asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs). More data from NEOWISE also have the potential to reveal a brown dwarf even closer to us than our closest known star, Proxima Centauri, if such an object does exist. Likewise, if there is a hidden gas-giant planet in the outer reaches of our solar system, data from WISE and NEOWISE could detect it.

“WISE has unearthed a mother lode of amazing sources, and we’re having a great time figuring out their nature,” said Edward (Ned) Wright, the principal investigator of WISE at UCLA.

“Even just one year of observations from the NEOWISE project has significantly increased our catalog of data on NEOs and the other small bodies of the solar systems,” said Lindley Johnson, NASA’s program executive for the NEO Observation Program.

The NEOs are asteroids and comets with orbits that come within 45 million kilometers (28 million miles) of Earth’s path around the sun.

The NEOWISE mission made use of the the WISE spacecraft, the Wide-field Infrared Survey Explorer that launched in December 2009. WISE scanned the entire celestial sky in infrared light about 1.5 times. It captured more than 2.7 million images of objects in space, ranging from faraway galaxies to asteroids and comets close to Earth.

However, in early October 2010, after completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold. But two of its four infrared cameras remained operational, which were still optimal for asteroid hunting, so NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt.

Now that NEOWISE has successfully completed a full sweep of the main asteroid belt, the WISE spacecraft will go into hibernation mode and remain in polar orbit around Earth, where it could be called back into service in the future.

In addition to discovering new asteroids and comets, NEOWISE also confirmed the presence of objects in the main belt that had already been detected. In just one year, it observed about 153,000 rocky bodies out of approximately 500,000 known objects. Those include the 33,000 that NEOWISE discovered.

NEOWISE also observed known objects closer and farther to us than the main belt, including roughly 2,000 asteroids that orbit along with Jupiter, hundreds of NEOs and more than 100 comets.

These observations will be key to determining the objects’ sizes and compositions. Visible-light data alone reveal how much sunlight reflects off an asteroid, whereas infrared data is much more directly related to the object’s size. By combining visible and infrared measurements, astronomers also can learn about the compositions of the rocky bodies — for example, whether they are solid or crumbly. The findings will lead to a much-improved picture of the various asteroid populations.

NEOWISE took longer to survey the whole asteroid belt than WISE took to scan the entire sky because most of the asteroids are moving in the same direction around the sun as the spacecraft moves while it orbits Earth. The spacecraft field of view had to catch up to, and lap, the movement of the asteroids in order to see them all.

“You can think of Earth and the asteroids as racehorses moving along in a track,” said Amy Mainzer, the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We’re moving along together around the sun, but the main belt asteroids are like horses on the outer part of the track. They take longer to orbit than us, so we eventually lap them.”

NEOWISE data on the asteroid and comet orbits are catalogued at the NASA-funded International Astronomical Union’s Minor Planet Center, a clearinghouse for information about all solar system bodies at the Smithsonian Astrophysical Observatory in Cambridge, Mass. The science team is analyzing the infrared observations now and will publish new findings in the coming months.

The first batch of observations from the WISE mission will be available to the public and astronomical community in April.

Source: NASA

January 28, 2011December 24, 2015 by Nancy Atkinson

Comet Tempel 1 Now in StardustNeXT’s Field of View

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. The panel on the right highlights the location of comet Tempel 1 in the frame. 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. Image credit: NASA/JPL-Caltech

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It’s comet ahoy! for the Stardust spacecraft, which is on its way to a Valentine’s Day meetup with comet Tempel 1. The images above 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). On Feb. 14, Stardust will fly within about 200 kilometers (124 miles) of the comet’s nucleus and for the first time we’ll get a second closeup look at Tempel 1.

“We were there in 2005 with the Deep Impact spacecraft, said Stardust-NExT Project Manager Tim Larson, speaking on today’s 365 Days of Astronomy podcast, “and this is a golden opportunity. It’s the first time we’ve ever been able to revisit a comet on a second pass near the sun.”

Larson said this encounter will give provide important information about how the surface of the comets change with each passage near the sun and whether the changes in the comet are global or just specific to certain areas on the surface.

From the Deep Impact mission, we already know that comet Tempel 1 has a wide variety of features on its surface.

“We have found smooth areas that look like material flows,” Larson said,” there are rough, pitted areas, there are craters on the surface, which we don’t know if they’re impact craters or if they’re caused by material coming out from the inside of the comet. So this is a very interesting comet in terms of variety of terrain.”

NASA's Deep Impact probe hits Comet Tempel 1 (NASA)

The exciting part will be comparing ‘before and after’ images of Tempel 1.

The spacecraft will be able to take up to 72 images and store them on board. Larson said the images will be carefully timed to center them around the closest approach to the comet, providing the best possible resolution.

“We should be able to get around three dozen images that are at better than 80 meters per pixel resolution and our closest approach images should be down below 20 meters per pixel resolution,” he said. “That will be good enough to resolve a lot of the key features on the surface of the comet and start that process of comparison.”

Artists concept of the stardust spacecraft flying throug the gas and dust from comet Wild 2. Credit: NASA/JPL

The repurposed Stardust spacecraft that flew past comet Wild 2 and brought back samples has just enough fuel to carry out maneuvers for the upcoming Tempel 1 flyby.

Larson said the preparations in designing the flyby sequences and software are almost complete and are being tested, and now the team is eagerly looking at the daily optical navigation images.

“We’re tracking where the comet is relative to the spacecraft,” he said, “and that will feed into our trajectory correction maneuvers. We have three more of those left before we arrive at the comet, and those will be used to target the spacecraft to the desired flyby point.”

The TCMs will occur on January 31, February 7, and then the last fully designed TCM will occur on February 12, two days before arrival.

There are challenges to using a recycled spacecraft.

“The primary challenge is, first of all, designing a new mission that it can accomplish with the fuel that it has left,” Larson said. “And through some clever mission design using some carefully timed trajectory correction maneuvers and taking advantage of some Earth gravity assists, we were able to modify the trajectory of the spacecraft to get it close to Tempel 1. So that’s been the primary challenge, and along with that is conserving the fuel that we have on board and making sure that we have enough fuel left to finish off this mission. Beyond that, there have been a few challenges in terms of aging equipment on board the spacecraft, — the spacecraft will be 12 years old in early February, and it’s well beyond its design life. And although everything is generally healthy on board, we have had a couple of pieces of equipment that were starting to age, and starting to degrade slightly. So we switched over to backup equipment so we were on fresh, healthy equipment, and we still have functioning equipment as backups.”

The closest approach will occur at 8:30 pm Pacific Time on February 14, 2011, where the spacecraft will be about 200 kilometers (125 miles) away from the surface of the comet, which is the closest any spacecraft has been to the surface of a comet.

January 19, 2011December 24, 2015 by Ken Kremer

Stardust NExT Targets Valentines Day Encounter with Comet Tempel 1

Stardust-NExT: 2 Comet Flybys with 1 Spacecraft. Stardust-NExT makes history on Valentine’s Day - February, 14, 2011 – by becoming the first spacecraft to visit 2 comets and gather science data: Comet Wild 2 in 2004 (left) and Comet Tempel 1 in 2011 (right). Artist renderings Credit: NASA. Collage: Ken Kremer. See video below of Jan 19, 2011 Media briefing from the Science Team about plans for the Temple 1 cometary encounter

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After a more than decade long journey of 6 billion kilometers, hopes are high for a celestial date in space between an icy comet and a thrusting probe on Valentine’s Day 2011. The rendezvous in space between NASA’s approaching Stardust-NExT spacecraft and Comet Tempel 1 takes place nearly on the exact opposite side of the Sun on Feb 14, 2011 at approximately 11:37 p.m. EST (8:37 p.m. PST).

The top science goal is to find out “how much the comet’s surface has changed between two close passages to the sun” since it was last visited in 2005, said principal investigator Joe Veverka of Cornell University, Ithaca, N,Y at a media briefing today, Jan 19, at NASA Headquarters. Indeed it’s the first time in history that a comet has been visited twice by space probes from Earth.

The lead scientists and engineers outlined the plans for the cometary flyby at the briefing. See a video of the entire briefing below.

Since the last visit in 2005, the comet has completed another orbit around the sun. “It will be the first time we’ll be able to see changes after a comet has passed through one perihelion,” explained Veverka. Tempel 1 belongs to the Jupiter family of comets and orbits between Mars and Jupiter.

Comet Tempel 1 suffered a cosmic collision during that first encounter with an emissary from Earth when NASA’s Deep Impact smashed a copper projectile directly into the comets nucleus. The blast created an impact crater and ejected an enormous cloud of gas and debris. Reflected light off the dust particles totally obscured the view of the crater and prevented any images from being taken. Researchers had hoped to determine the size of the crater. A lot of bets hinge on that determination.

“We have a chance to complete the Deep Impact experiment. We hope to see how big the impact crater is and what that tells us about the mechanical properties, ” said Veverka.

20 Jan. 2011 Position of STARDUST-NExT probe - Looking Down on the Sun.
This image shows the current position of the STARDUST-NExT spacecraft and the spacecraft's trajectory (in blue) around the Sun. Credit: NASA

With just over 3 weeks remaining, the craft is approximately 24.6 million kilometers (15.3 million miles) away from its encounter. Stardust-NExT will zoom past the nearly 6-kilometer-wide comet (3.7 miles) at a distance of approximately 200 kilometers (124 miles) and at a speed of 10 km/sec according to Tim Larson, the mission’s project manager from the Jet Propulsion Laboratory (JPL), Pasadena, Calif.

“The spacecraft is still working well 12 years after launch. This is a bonus mission with a scientifically desirable target which we can get close to,” said Larson.

“Everything will happen autonomously,” stated Larson. “The craft will be about 2 AU away from Earth at encounter. Since the round trip signals will take about 40 minutes there is no chance for any real time changes.”

Different features on Tempel 1 discovered by Deep Imapct in 2005. Credit: NASA

“Stardust-NExT will take 72 high resolution images during the close approach encounter. These will be stored in an onboard computer and relayed back to Earth starting about an hour later. It will take about 12 hours to get them all back.”

NASA says that after processing, the images are expected to be available at approximately 4:30 a.m. EST (1:30 a.m. PST) on Feb. 15.

“For the first time we’ll go back to see what happens to a comet since our last visit,” explained Pete Schultz, co-investigator of Brown University, Providence, R.I. “The comet has been out to the orbit of Jupiter and back to Mars and had several outbursts of gas and dust. In 2005 we saw old and new surfaces. So it has a complicated geologic history. We hope to resolve the crater and see ejecta. But there are many unknowns. What we see – whether its the crater or the other unseen side – all depends on the rotation of the comet nucleus.”

“The comet dynamics are complex and erratic, not inert,” said Steve Chesley, a co-investigator at JPL. “They are like a rocket with no one at the controls. The orbit can change. So it is a huge challenge to target a spacecraft for a flyby or rendezvous.”

Stardust successful original mission was to fly by Comet Wild 2 on Jan 2, 2004. It then returned cometary dust particle in a sample return canister to Earth on Jan. 19, 2006 which reentered the atmosphere at the highest speed ever and parachuted to a safe landing. Credit: NASA

Stardust-NeXT is a repurposed spacecraft. The Valentine’s Day encounter will be the last hurrah for the aging probe. Stardust was originally launched way back in 1999. It flew by Comet Wild 2 on Jan. 2, 2004 and collected cometary dust particles which were returned to Earth in a sample return capsule in Jan. 2006. Since then it has continued its solitary voyage through the void of the space.

The craft is nearly out of fuel and all movements consume fuel. It is totally dependent on the reaction control thrusters for navigating through space and pointing its camera and science instruments, said Larson.

“We are confident that we will have enough fuel to finish up this mission. It has been a big, big challenge to maintain a reserve supply. After the mission there won’t be much left that the spacecraft can do. The last trajectory correction maneuver is two days before arrival. That is also when we will take our last optical navigation images for targeting the spacecraft.”
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Only about a third of the surface of Tempel 1 was photographed by Deep Impact in 2005. “We’ll be looking at old territory and new and some overlap,” explained Veverka. “The science team is awfully excited and just can’t wait to see the pictures on Valentine’s day.”

“We have no idea how quickly the surface features change and whether its millions of years or days,” concluded Veverka.

“We expect new discoveries no matter what we see,” Larson summed up

Stardust-NExT Spacecraft & Comet Tempel 1. Artist rendering of Stardust-NExT spacecraft nearing Comet Tempel 1 for upcoming flyby on February, 14, 2011. Credit: NASA
See video and graphics below of Jan 19, 2011 Media briefing from the Science Team about plans for the cometary encounter

Planned imaging of Comet Tempel 1 by Stardust-NExT during flyby. Blue area is unseen and unmapped territory never imaged by Deep Impact during 2005 flyby. Bulls eye in yellow area is expected location of 2005 impact crater and expected new coverage. There is some overlap. Credit: NASA

Jan. 19, 2010: Science Team Media Briefing

The Stardust spacecraft has been repackaged for the Stardust-NexT mission. Stardust-NExT will rendezvous with Comet Tempel 1 on February 14, giving scientists an opportunity, for the first time, to search a comet’s surface for changes following its orbit around the sun. Mission scientists discussed the relevance of the mission at a briefing at NASA headquarters in Washington

Stardust successful original mission was to fly by Comet Wild 2 on Jan 2, 2004 and return cometary dust particle to earth in Jan. 2006. It is equipped with 3 science instruments. Credit: NASA

January 10, 2011December 24, 2015 by Ken Kremer

35 Days to STARDUST-NeXT Valentines Day Flyby of Comet Tempel 1

Stardust-NExT Spacecraft & Comet Tempel 1. Artist rendering of Stardust-NExT spacecraft nearing comet Tempel 1.

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35 Days and Counting !

NASA’s re-purposed STARDUST- NeXT spacecraft is set to flyby Comet Tempel 1 at a distance of just 200 km on Valentine’s Day – February 14, 2011 at about 8:36 p.m. PST. The encounter marks the first time that a comet has been visited twice by probes from Earth. The revisit also provides the first opportunity for up-close observations of a comet both before and after a single orbital pass around the sun.

Comet Tempel 1 was first visited by NASA’s Deep Impact comet smashing mission in July 2005. Deep Impact delivered a 375 kg projectile into the path of Temple 1 that resulted in a high speed impact directly into the comet nucleus.

The cosmic collision of about 10.2 km/sec (22,800 miles/hour) ejected a cloud of debris that was studied by the Deep Impact spacecraft as well as an armada of orbiting and ground based telescopes. The impact crater itself was obscured by the debris cloud. The spacecraft did find the first evidence of surface ice on a comet instead of just inside a comet. Stardust NExT will take images and spectra of Tempel 1 and hunt for the impact crater.

Artists concept of NASA’s STARDUST- NeXT probe which will fly by Comet Tempel 1 on Feb. 14, 2011. Credit: NASA

According to the latest update posted at the STARDUST- NeXT mission website on Jan 6; “The spacecraft is healthy and began the New Year with a cold boot to clear a memory address latch-up that had occurred late in 2010. This cold boot clears the latched line and resets the memory to its factory settings.”

The reboot was completely successful and sets the probe up to accomplish the missions science objectives. On board optical navigation cameras were scheduled to take a new set of images on Jan. 6.

The update further states that the mission plan has now changed substantially to accommodate two new challenges. First the estimated fuel remaining on board is lower than expected. Second, the optical navigation cameras failed to detect the comet in the prior set of images in December.

10 Jan. 2011 Position of STARDUST-NeXT probe - Looking Down on the Sun. This image shows the current position of the STARDUST spacecraft and the spacecraft's trajectory (in blue) around the Sun. Credit: NASA

The optical cameras provide the key information to precisely navigate the probe to the comet. “Current estimates show that the comet may not be bright enough to detect with the Navcam until the latter half of January,” states the update.

As a result of the lower fuel estimate the remaining trajectory maneuvers (TCM’s) have been adjusted to January 31, February 7, and February 12. No science images will be taken until the last 7 days prior to the Feb 14 encounter.

Caption: Video of Comet Tempel 1 as NASA’s Deep Impact comet spacecraft delivers a projectile which smashed into the comet in July 2005. NASA’s STARDUST- NeXT probe is set to flyby Comet Tempel 1 on February, 14, 2011. The probe will collect numerous high resolution images of the coma and nucleus and hunt for the elusive 2005 impact crater.

The team states that these changes will provide “positive fuel margin through encounter …. and places the TCMs at times best able to accommodate late detection of the comet”.

The engineering team is building new approach sequences to accommodate these significant changes to the approach and Comet Tempel 1 encounter on Feb 14.

A briefing by the science team will be carried live on NASA TV on Jan. 19 at 2 PM EST

The Stardust spacecraft accomplished its original goal of flying through a dust cloud surrounding the nucleus of comet Wild 2 in Jan. 2004. The probe successfully gathered particles of cometary material during the flyby, The comet particles were returned to Earth aboard a sample return capsule which landed in the Utah desert in January 2006.

Comet particle tracks in aerogel returned to Earth by STARDUST in January 2006

December 28, 2010December 24, 2015 by Nancy Atkinson

SOHO Finds Its 2000th Comet

Image Left: SOHO's 2000th comet, spotted by a Polish amateur astronomer on December 26, 2010. Credit: SOHO/Karl Battams. Image Right: In 15 years since it launched in December 1995, the SOHO spacecraft, has doubled the number of comets sighted in the three hundred years previously. Credit: NASA/ESA/Alex Lutkus

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From a NASA Press Release:

As people on Earth celebrate the holidays and prepare to ring in the New Year, an ESA/NASA spacecraft has quietly reached its own milestone: on December 26, the Solar and Heliospheric Observatory (SOHO) discovered its 2000th comet.

Drawing on help from citizen scientists around the world, SOHO has become the single greatest comet finder of all time. This is all the more impressive since SOHO was not specifically designed to find comets, but to monitor the sun.

“Since it launched on December 2, 1995 to observe the sun, SOHO has more than doubled the number of comets for which orbits have been determined over the last three hundred years,” says Joe Gurman, the U.S. project scientist for SOHO at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Of course, it is not SOHO itself that discovers the comets — that is the province of the dozens of amateur astronomer volunteers who daily pore over the fuzzy lights dancing across the pictures produced by SOHO’s LASCO (or Large Angle and Spectrometric Coronagraph) cameras. Over 70 people representing 18 different countries have helped spot comets over the last 15 years by searching through the publicly available SOHO images online.

The 1999th and 2000th comet were both discovered on December 26 by Michal Kusiak, an astronomy student at Jagiellonian University in Krakow, Poland. Kusiak found his first SOHO comet in November 2007 and has since found more than 100.

“There are a lot of people who do it,” says Karl Battams who has been in charge of running the SOHO comet-sighting website since 2003 for the Naval Research Lab in Washington, where he also does computer processing for LASCO. “They do it for free, they’re extremely thorough, and if it wasn’t for these people, most of this stuff would never see the light of day.”

Battams receives reports from people who think that one of the spots in SOHO’s LASCO images looks to be the correct size and brightness and headed for the sun – characteristics typical of the comets SOHO finds. He confirms the finding, gives each comet an unofficial number, and then sends the information off to the Minor Planet Center in Cambridge, Mass, which categorizes small astronomical bodies and their orbits.

It took SOHO ten years to spot its first thousand comets, but only five more to find the next thousand. That’s due partly to increased participation from comet hunters and work done to optimize the images for comet-sighting, but also due to an unexplained systematic increase in the number of comets around the sun. Indeed, December alone has seen an unprecedented 37 new comets spotted so far, a number high enough to qualify as a “comet storm.”

LASCO was not designed primarily to spot comets. The LASCO camera blocks out the brightest part of the sun in order to better watch emissions in the sun’s much fainter outer atmosphere, or corona. LASCO’s comet finding skills are a natural side effect — with the sun blocked, it’s also much easier to see dimmer objects such as comets.

“But there is definitely a lot of science that comes with these comets,” says Battams. “First, now we know there are far more comets in the inner solar system than we were previously aware of, and that can tell us a lot about where such things come from and how they’re formed originally and break up. We can tell that a lot of these comets all have a common origin.” Indeed, says Battams, a full 85% of the comets discovered with LASCO are thought to come from a single group known as the Kreutz family, believed to be the remnants of a single large comet that broke up several hundred years ago.

The Kreutz family comets are “sungrazers” – bodies whose orbits approach so near the Sun that most are vaporized within hours of discovery – but many of the other LASCO comets boomerang around the sun and return periodically. One frequent visitor is comet 96P Machholz. Orbiting the sun approximately every six years, this comet has now been seen by SOHO three times.

SOHO is a cooperative project between the European Space Agency (ESA) and NASA. The spacecraft was built in Europe for ESA and equipped with instruments by teams of scientists in Europe and the USA.

For more information see the SOHO website. .

See SOHO realtime data.

December 12, 2010December 24, 2015 by Mike Simonsen

Asteroid Scheila Sprouts a Tail and Coma

(596) Scheila, the asteroid with a tail. Image credit: Peter Lake

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When is an asteroid not an asteroid? When it turns out to be a comet, of course. Has this ever happened before? Why, yes it has. In fact it was just announced December 12, 2010 that the asteroid (596) Scheila has sprouted a tail and coma! This is likely a comet that has been masquerading as an asteroid.

Taken from New Mexico Skies between 8h15m and 11h45m UT. The image is a stack of 10 x 600 sec exposures using a 20 inch RCOS and STL11K camera. Scale is 0.91 asec/px.. Image courtesy of Joseph Brimacombe

See an animation by Joseph Brimacombe at this link.

Steve Larson of the Lunar and Planetary Laboratory (LPL), University of Arizona first reported that images of the minor planet (596) Scheila taken on December 11th showed the object to be in outburst, with a comet-like appearance and an increase in brightness from magnitude 14.5 to 13.4. The cometary appearance of the object was confirmed by several other observers within hours.

A quick check of archived Catalina images of Scheila from October 18, November 2 and November 11 showed Scheila to look star-like, which is what asteroids look like from Earth. They just happen to be moving across the field of view in contrast to the fixed background stars. The image taken by Catalina on December 3rd shows some slight diffuseness and an increase in overall brightness. So, it appears this event began on or around December 3rd.

Upon hearing the news, there was some speculation that this might be evidence of an impact event. Had something crashed into asteroid Scheila? It seems unlikely, and this is a story we have heard before.

The asteroid discovered in 1979 and named 1979 OW7 was lost to astronomers for years and then recovered in 1996. It was subsequently renamed 1996 N2. That same year it was discovered to have a comet-like appearance, and many believed this was the signature of an impact between two asteroids. After years of inactivity 1996 N2 sprouted a tail again in 2002. One collision between two asteroids was unlikely enough. The odds of it happening again to the same object were essentially zero. What we had was a comet masquerading as an asteroid. This object is now known by its cometary name 133P/Elst-Pizarro, named after the two astronomers who discovered its initial cometary outburst.

The 2002 outburst and the discovery of more active asteroids showing mass-loss led to a paper (Hsieh and Jewitt 2006, Science, 312, 561-563) introducing an entirely new class of solar system objects, Main Belt Comets (MBC). MBCs look like comets because they show comae and have tails but they have orbits inside Jupiter’s orbit like main belt asteroids.

The most likely cause of the mass loss activity in MBCs is sublimation of water ice as the surface of the MBC is heated by the Sun. This is suggested most strongly by the behavior of the best-studied example, namely 133P/Elst-Pizarro. Its activity is recurrent, and it is strongest near and after perihelion, the point in its orbit nearest the Sun, like other comets.

MBCs are interesting to astronomers because they appear to be a third reservoir of comets in our solar system, distinct from the Oort cloud and Kuiper belt. Since we know of no way for these other reservoirs to have deposited comets in the inner solar system, the ice in MBCs probably has a different history than the ice in the outer comets. This allows researchers to study the differences in the Sun’s proto-planetary disk at three separate locations. This might lead to information on the Earth’s oceans, one of the continuing lines of investigation by solar system scientists.

Now it seems we have another MBC to add to the sample. And Scheila will probably be getting a new name soon. Asteroid (596) Scheila was discovered Feb. 21, 1906, by A. Kopff at Heidelberg. The 113Km in diameter ‘asteroid’ was named after an acquaintance, an English student at Heidelberg. In the future it will be called XXXP/Lawson or something similar, and Kopff’s Scheila will become just another footnote in the history of astronomical nomenclature.