Siding Spring Comet via WISE. credit: NASA/JPL-Caltech/UCLA
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An old story got new legs this week as word went viral of a possible new 9th planet in our solar system – a gas giant bigger than Jupiter – which could be hiding somewhere in the Oort Cloud, just waiting to be found.
An article this week in The Independent suggested the new planet, called Tyche, had already been found among data from the WISE mission. This prompted the WISE team to post a rebuttal on their Facebook page: “Not true. A pair of scientists published a paper stating that if such a big planet exists in the far reaches of the Solar System, then WISE should have seen it. That is true. But, analysis over the next couple of years will be needed to determine if WISE has actually detected such a world or not.”
To make sense of this all, Universe Today sought out a scientist who has looked at the outer solar system as much as anyone, if not more: Mike Brown, of Eris, Haumea and Makemake fame – to get his take on Tyche.
“Yes,” said Brown, “this is all getting pretty funny these days!”
The story starts at least a decade ago. For years John Matese of the University of Louisiana at Lafayette and colleague Daniel Whitmire have been trying to figure out why many of the comets that originate from way out in the distant-most part of our solar system — the Oort Cloud — have strange orbits that don’t jive with theories of how comets should behave. The two scientists first suggested that the gravitational influence from a dark companion to the Sun — a dim brown-dwarf or red-dwarf star — was sending comets careening towards the inner solar system. They called it Nemesis, (another thing that went viral), but the Nemesis idea has widely been refuted.
Last year, Matese and Whitmire suggested that possibly a large planet four times the mass of Jupiter in the Oort Cloud could explain why long-period comets appear to be clustered in a band inclined to the ecliptic instead of coming from random directions. (Here’s their paper.)
Then came a revival of their theory with several articles about it this week, reporting it as seemingly fact.
Could there possibly be a giant planet 500 times as distant as Neptune?
“Absolutely,” Brown said. “Many people have speculated about such possibilities for a long time. It’s an intriguing idea because, well, it would be fun, to say the least.”
But beyond fun and excitement, is there actually any evidence for it?
The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA
“Well, the quality of the data that Matese and Whitmire have to work with is pretty crummy –no fault of their own — it’s just the historical record of where comets have come from,” Brown said in an email. “I don’t believe that anyone understands the ins and outs of the data set well enough to really draw a robust conclusion. But, Matese and Whitmire did the best they could and think the data point to something out there.”
Does Brown think there is really something out there?
“Well,” he said, “if I had to bet one way or another I’d bet no. The data don’t convince me, and there is no other hint anywhere that such a thing is real. So I’m pretty skeptical.”
That being said, however, Brown believes WISE really does have a good chance of detecting this type of object way out there – if it exists — even if the predictions have nothing to do with the real object.
“This is something that people will absolutely be looking for when the data are released,” Brown said, “and, indeed, the WISE team is undoubtedly already looking for — not because of the prediction, but simply because it’s the right way to search this unknown region of the solar system!”
So don’t worry about the International Astronomical Union having to confirm or name a new planet in our solar system, at least for now.
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
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.
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.
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
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
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/JPL2. “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
Stardust-NExT Spacecraft & Comet Tempel 1.
Artist rendering of upcoming flyby on February, 14, 2011. Credit: NASA13 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/JPLEnlargement 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
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.
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 encounterPlanned 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: NASAPlanned 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. 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
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
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
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.
(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
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.
This 3-D image shows the entire nucleus of Hartley 2 with jets and an icy particle cloud. Circles have been added to highlight the location of individual particles. Image Credit: NASA/JPL-Caltech/UMD/Brown
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As Jessica Sunshine said, Comet Hartley 2 might be the smallest of the five comets that our spacecraft have visited, but no doubt it is the most interesting, and for its size, the most active. Sunshine is the EPOXI mission deputy principal investigator, and she and her team have had the chance to analyze images from the Nov. 4 flyby of the comet. Closeup views yielded some big surprises: Hartley 2 is throwing snowballs.
“When we first saw all the specks surrounding the nucleus, our mouths dropped,” said Pete Schultz, EPOXI mission co-investigator at Brown University. “Stereo images reveal there are snowballs in front and behind the nucleus, making it look like a scene in one of those crystal snow globes.”
Estimates of the size of the largest particles ranges from a golf ball to a basketball.
Another surprise, which was noted almost immediately from the flyby images, were that the very active jets on the comet were powered by carbon dioxide. “This is the first time we’ve ever seen individual chunks of ice in the cloud around a comet or jets definitively powered by carbon dioxide gas,” said Michael A’Hearn, principal investigator for the spacecraft. “We looked for, but didn’t see, such ice particles around comet Tempel 1,” the comet that the Deep Impact spacecraft flew by in 2005.
Here are highlights from the press conference last week, along with some of the fantastic imagery of Comet Hartley 2.
Hartley 2 CO2 jet up close. Credit: NASA/JPL-Caltech/UMD/Brown Comet Hartley 2 can be seen in glorious detail in this image from NASA's EPOXI mission. It was taken as the spacecraft flew by around 6:59 a.m. PDT (9:59 a.m. EDT), from a distance of about 700 kilometers (435 miles). The comet's nucleus, or main body, is approximately 2 kilometers (1.2 miles) long and .4 kilometers (.25 miles) at the 'neck' or most narrow portion. Jets can be seen streaming out of the nucleus. Image credit: NASA/JPL-Caltech/UMDThis image from the High-Resolution Instrument on NASA's EPOXI mission spacecraft shows part of the nucleus of comet Hartley 2. The sun is illuminating the nucleus from the right. A distinct cloud of individual particles is visible. This image was obtained on Nov. 4, 2010, the day the EPOXI mission spacecraft made its closest approach to the comet. Image Credit: NASA/JPL-Caltech/UMD Infrared scans of comet Hartley 2 by NASA's EPOXI mission spacecraft show carbon dioxide, dust, and ice being distributed in a similar way and emanating from apparently the same locations on the nucleus. Water vapor, however, has a different distribution implying a different source region and process. Image Credit: NASA/JPL-Caltech/UMDThis zoomed-in image from the High-Resolution Instrument on NASA's EPOXI mission spacecraft shows the particles swirling in a 'snow storm' around the nucleus of comet Hartley 2. Scientists estimate the size of the largest particles ranges from a golf ball to a basketball. They have determined these are icy particles rather than dust. The particles are believed to be very porous and fluffy. Image Credit: NASA/JPL-Caltech/UMDThe motion of some icy particles in the cloud around Hartley 2, as seen by NASA's EPOXI mission spacecraft. A star moving through the background is marked with red and moves in a particular direction and with a particular speed, while the icy particles move in random directions. The icy particles are marked in green, blue and light blue. Image Credit: NASA/JPL-Caltech/UMD/Brown This image shows the nuclei of comets Tempel 1 and Hartley 2, as imaged by NASA's Deep Impact spacecraft, which continued as an extended mission known as EPOXI. Tempel 1 is five times larger than Hartley 2. Visible jets are easily seen in images of Hartley 2, but required extensive processing to be seen in images of Tempel 1. Tempel 1 is 7.6 kilometers (4.7 miles) in the longest dimension. Hartley 2 is 2.2 km (1.4 miles) long. The Tempel 1 image was built up from more than 25 images captured by the impactor targeting sensor on July 4, 2005. The Hartley 2 image was obtained by the Medium- Resolution Imager on Nov. 4, 2010.
The folks from UnmannedSpaceflight.com have done it again. Daniel Machácek created this wonderful animation from just the five initial images of Hartley 2 that were released by the Deep Impact team immediately following its flyby on November 4, 2010, using Sqirlz Morph software. Time in the animation is five times faster than the actual speed of the flyby. Hartley 2 really does look like a flying bowling pin, except this one is 2km (1.25 miles) long and about .2 km in diameter. Thanks to Daniel for sharing his animation.
Comet Hartley as seen by the EPOXI spacecraft at closest approach. Credit: NASA
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NASA’s Deep Impact spacecraft came within 700 kilometers (435 miles) of Comet Hartley 2 at 10:01 a.m. EDT (1401 GMT) today, imaging with several cameras. Here are the first pictures released of the closest approach.
The scientific team watched along with viewers online and on NASA TV as the images were returned to Earth, about an hour after the spacecraft made its closest approach. First impressions? It is a peanut with jets.
“This is a type of moment that scientists live for,” said JPL’s Don Yeomans, “to get new results in such a dramatic fashion. The images are clear, taken as spacecraft was approaching, then as it swung past and moved away.”
The Sun is off to right, and visible is the icy surface of the comet throwing dust and gas towards the Sun.
Another view of Comet Hartley 2 during EXPOXI close approach. Credit: NASA
More images will be coming down from the spacecraft and Yeomans said the scientists will be examining Hartley 2, looking for the origination spots of the jets. “Are the jets coming from the surface, or is it coming from well beneath where heat of Sun reaches into the comet? We’ll be looking for how many jets, or if possibly the whole comet outgassing. There is a single obvious jet coming off towards the Sun, but also you can see one at the 7 o’clock position, which was evident in previous images, too.”
Image of Hartley 2 as the EXPOXI spacecraft moved away from comet. Credit:NASA
The spacecraft uses several high-resolution instruments, and one camera can image the entire comet with a resolution of about seven meters (about 23 feet) per pixel. The spacecraft also acquired 199 medium-resolution images.
From previous images taken by EPOXI from a distance and radar images taken from the ground, scientists knew Hartley 2 was a bi-lobate comet, which means peanut- or pickle-shaped. But they didn’t know if it was a solid surface or a contact binary, where two smaller cometesimals were stuck together.
But, Yeomans said, these images show the comet is of a solid, one-piece construction.
EPOXI Principal Investigator Mike A’Hearn agreed. “Every time we go to a comet they are full of big surprises,” he said. “The comets we’ve seen up close all seem to work the same way, but they look very different so there must be some fundamental differences in the ways they work. It could be they came from different parts of the early solar system or that they evolved very differently. Finding out how the solar system formed is really what we want out of this.”
The discoverer of Hartley 2, Malcolm Hartley, was on hand at JPL for the closest approach. He found the comet 26 years ago as a smudge on photographic plates taken at the Siding Spring Observatory in Australia. “I was doing quality control of photographic plates and I noticed faint object with a telltale glow like a comet,” said Hartley, who still works at the same observatory. “It has been very interesting to be here, and it has been interesting for the science team and quite a challenge for the engineers. There’s going to be enough data downloaded to keep researchers busy for several years.”
