Animation showing the comet moving against the background of stars. Images taken at the Pan-STARRS 1 Telescope on the night of June 5-6, 2011. Hawaii time is 10 hours earlier than Universal Time (UT). Credit: Henry Hsieh, PS1SC
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Pan-STARRS… Doesn’t that conjure up an image of a faceless stranger whispering in the dark, passing their hand over a clear sky and leaving a glittering trail? Pan-STARRS… Take the second star on the left and go straight on ’til morning. Pan-STARRS… Regardless of my flights of fancy, Pan-STARRS is a telescopic reality and its home is Mount Haleakala, Hawaii. The Panoramic Survey Telescope and Rapid Response System is renowned for its wide-field imaging capabilities – and its mission to alert planet Earth of potentially dangerous objects approaching. Now the most recent discovery is a comet which may be visible to the naked eye in early 2013.
Discovered on the night of June 5-6 using the Pan-STARRS 1 telescope, the moving rogue was confirmed to be a comet on the following night by astronomer Richard Wainscoat and graduate student Marco Micheli using the Canada-France-Hawaii Telescope on Mauna Kea. The Oort Cloud visitor quickly had its orbit calculated by the Harvard Minor Planet Center and shows it will be visiting in our solar system within about 30 million miles (50 million km) of the Sun in early 2013. While that’s about the same distance as the Sol / Mercury factor, the comet will not encounter Earth… just give us a good show.
Wainscoat said, “The comet has an orbit that is close to parabolic, meaning that this may be the first time it will ever come close to the sun, and that it may never return.” Just like our stranger in the dark, eh?
Will this new comet named C/2011 L4 (PANSTARRS) create a spectacle? It’s not easy to judge. While it is expected to be brightest in February or March 2013, it depends on how much ice it contains as to how bright it will become. Another factor is positioning. Since it will be low to the west at sunset, sky brightness may also make it difficult to observe. Right now C/2011 L4 is about 700 million miles (1.2 billion km) from the Sun, placing it beyond the orbit of Jupiter and only able to be spotted using a large telescope and imaging equipment. It will take several months of observation for more accurate assessments, but astronomers are cautious since many predictions can end up being a cometary dud. There’s no doubt it will be here – but there’s always uncertainties as to how bright it will be.
In the mean time, we’ll take Pan-STARRS whispering word for it… and believe.
Jets can be seen streaming out of the nucleus, or main body, of comet Hartley 2 in this image from NASA's EPOXI mission. The nucleus is approximately 2 kilometers (1.2 miles) long and .4 kilometers (.25 miles) across at the narrow "neck." Credit: NASA/JPL-Caltech/UMD
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No, EPOXI isn’t the name of a new super glue, but an abbreviation for the continuation of Deep Impact. While the original mission to study Comet 9P/Tempel was a huge success, the spacecraft continues to explore objects of opportunity. Its name is derived from Extrasolar Planet Observations and Characterization (EPOCh) and the Deep Impact Extended Investigation (DIXI)… and it’s now fulfilling another goal as it swings by Comet Hartley 2. It approached, encountered and departed, sending back 117,000 images and spectral findings – along with some surprising observations.
“From all the imaging we took during approach, we knew the comet was a little skittish even before flyby,” said EPOXI Project Manager Tim Larson of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “It was moving around the sky like a knuckleball and gave my navigators fits, and these new results show this little comet is downright hyperactive.”
What EPOXI found was a “hyperactive comet” – one that didn’t react in anticipated ways. From a distance of 431 miles (694 kilometers), the spacecraft watched as water and carbon-dioxide jets erupted from the flying space rock’s surface. While this in itself isn’t unusual, the fact that it didn’t happen uniformly caused scientists to sit up and take notice. Jets occurred at both ends of the comet with the strongest activity centered on the small end. Water vapor ejected from the central portion showed a notable lack of carbon-dioxide and ice, leading investigators to speculate the material was re-deposited from the ends of Hartley 2.
“Hartley 2 is a hyperactive little comet, spewing out more water than most other comets its size,” said Mike A’Hearn, principal investigator of EPOXI from the University of Maryland, College Park. “When warmed by the sun, dry ice — frozen carbon dioxide — deep in the comet’s body turns to gas jetting off the comet and dragging water ice with it.”
A large, diffuse cloud of CN gas surrounds the nucleus of Hartley 2 in this image from NASA's EPOXI mission. The gas forms a cloud of more than 200,000 kilometers (about 124,000 miles) in radius, compared to the comet's size of about 2 kilometers (1.24 miles). Credit: NASA/JPL-Caltech/UMDIs Hartley 2 unique? No. Scientists are aware of at least a dozen comets that behave similarly, but this is the first we’ve been able to examine closely via a spacecraft. These odd comets are extremely active for their size and may be driven by carbon dioxide or carbon monoxide. “These could represent a separate class of hyperactive comets,” said A’Hearn. “Or they could be a continuum in comet activity extending from Hartley 2-like comets all the way to the much less active, “normal” comets that we are more used to seeing.”
What makes this new class of comets so unusual? Just three ingredients: deposits around the inactive center which may have originated at the ends, a tumbling state of rotation and a large end containing ubiquitous inclusions which can span`approximately 165 feet (50 meters) high and 260 feet (80 meters) wide. EPOXI also picked up another surprise at Hartley 2’s smaller end – shiny cubicals reaching 16 stories tall and two to three times more reflective than other average surface materials. But that’s not all. For nine days in September, the energetic comet expelled 10 million times more CN gas in its coma – a dramatic and unexpected change called the “CN anomaly”. It was analyzed by McFadden and Dennis Bodewits, a former postdoctoral fellow at NASA Goddard who is now at the University of Maryland, and their colleagues. This comet exhaust normally includes a similar amount of dust, but not in this case.
“We aren’t sure why this dramatic change happened,” says McFadden. “We know that Hartley 2 gives off considerably more CN gas than comet Tempel 1, which was studied earlier by a probe released by the Deep Impact spacecraft. But we don’t know why Hartley 2 has more CN, and we don’t know why the amount coming off the comet changed so drastically for a short period of time. We’ve never seen anything like this before.”
Left: Comet Churyumov-Gerasimenko is hidden within this sector of space, a crowded star field in the constellation Scorpius that is towards the center of our galaxy. The image was taken by OSIRIS's wide-angle camera. Middle: The narrow-angle camera allows for a closer look, and shows many background stars. Right: After refined steps of data processing the comet becomes visible. (Credits: ESA 2011 MPS for OSIRIS-Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA)
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About 163 million kilometers and three more years separate brave little ESA spacecraft – Rosetta – from comet Churyumov-Gerasimenko. But this seemingly huge distance isn’t stopping determined scientists from the Max Planck Institute for Solar System Research (MPS) in Germany. Their target might be a million times fainter than the faintest star we can see here on Earth with our eyes, but Rosetta has them covered. It has succeeded in imaging the distant comet and it’s right on target.
Using the onboard camera system OSIRIS, Rosetta took its snapshots during testing over the last couple of weeks in preparation for its three year hibernation period. These first images of the tiny, flying space stone only covered a few pixels; “But the pictures already give us a good idea of where we are headed”, says Dr. Holger Sierks from MPS, OSIRIS Lead Investigator. “In addition, they are a remarkable proof of the camera’s performance. We had not expected to be able to create first images from so far away”.
Credits: ESA 2011 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA and Yuri Beletsky / ESORight on? You bet. Here on Earth we’re only able to follow Comet Churyumov-Gerasimenko with the aid of the European Southern Observatory’s Very Large Telescope in Chile, one of the world’s most powerful telescopes with a main mirror diameter of eight meters. By comparison, Rosetta’s OSIRIS camera mirror measures only approximately ten centimeters in diameter. Just like our terrestrial astrophotos, OSIRIS also needed to make a long exposure time as well – to the tune of 13 hours. “All in all, we took 52 images with OSIRIS, each exposed for 15 minutes”, explains Dr. Colin Snodgrass from MPS, responsible for data processing. Once the images were obtained, they were then “stacked” to correct for the comet’s movement against the background stars. This gave researchers their first glimpse of their final destination.
But now it’s going to be a long wait until Rosetta spots the stone again…
Operations manager Andrea Accomazzo gestures happily in the Rosetta control room at ESOC today, just moments after the final command was sent to Rosetta to trigger a 31-month hibernation until January 2014. Credits: ESAThe final command to put Rosetta into sleep mode was sent at 08:00 UT on June 8, 2011. The systems are now shut down for 31 months until the intrepid spacecraft nears its destination in 2014. Its instruments and control systems might be silent for awhile, but its 10 year voyage has been a huge success thus far. “With flybys of asteroids Steins in 2008 and Lutetia in 2010, Rosetta has already delivered excellent scientific results,” says Paolo Ferri, Head of ESOC’s Solar and Planetary Mission Operations Division. Rosetta is simply conserving its solar power until it reaches rendezvous with 67-P/Churyumov-Gerasimenko. But, it’s not entirely silent. The on-board computers and a few heaters are still ticking away – keeping time until its orbit takes it from 660 million km from Sol.
“We sent the command via NASA’s 70 m Deep Space Network station in Canberra, Australia, ensuring the signal was transmitted with enough power to reach Rosetta, which is now 549 million km from Earth,” said ESA’s Spacecraft Operations Manager Andrea Accomazzo. “We’ll monitor via ESA’s 35 m station at New Norcia in Australia for a few days to see if any problems occur, but we expect to receive no radio signal until 2014. Rosetta’s on her own now.”
Is there a handsome prince waiting in Rosetta’s future? Yes, in the form of a timer which will wake the slumbering spacecraft princess. When the moment arrives a signal will be transmitted back to Earth and mission control will then take command. Over a period of weeks Rosetta will “warm up” again in preparation for its landmark arrival at the distant, icy space stone. “Hibernation is a necessary step to reach the final target.” says Ferri. “We are now looking forward to 2014, when Rosetta becomes the first spacecraft to track the life of a comet as it arcs in toward the Sun.”
It starts out innocently enough: a small speck against a field of background stars, barely noticeable in the image data. But… it’s a speck that wasn’t there before. Subsequent images confirm its existence – there’s something out there. Something bright, something large, and it’s moving through our solar system very quickly. The faint blur indicates that it’s a comet, an icy visitor from the outermost reaches of the solar system. And it’s headed straight toward Earth.
Exhaustive calculations are run and re-run. Computer simulations are executed. All possibilities are taken into consideration, and yet there’s no alternative to be found; our world will face a close encounter with a comet in mere months’ time. Phone calls are made, a flurry of electronic messages fly between computer terminals across the world, consultations are held with top experts in the field. We are unprepared… what can we do? What does this mean for civilization as we know it? What will this speeding icy bullet from outer space do to our planet?
The answer? Nothing.
Nothing at all. In fact, it probably won’t even be very interesting to look at – if you can even find it when it passes by.
(Sorry for the let-down.)
There’s been a lot of buzz in the past several months regarding Comet Elenin, a.k.a. C/2010 X1, which was discovered by Russian astronomer Leonid Elenin on December 10, 2010. Elenin spotted the comet using a telescope in New Mexico remotely from his location in Lyubertsy, Russia. At that time it was about 647 million kilometers (401 million miles) from Earth… in the time since it has closed the distance considerably, and is now around 270 million km away. Elenin is a long-period comet, which means it has a rather large orbit around the Sun… it comes in from a vast distance, swings around the Sun and heads back out to the depths of the solar system – a round trip lasting over 10,000 years. During its current trip it will pass by Earth on October 16, coming as close as 35 million km (22 million miles).
Elenin's orbit via the JPL Small-Body Database Browser
Yes, 22 million miles.
That’s pretty far.
Way too far for us to be affected by anything a comet has to offer. Especially a not-particularly-large comet like Elenin.
Some of the doomy-gloomy internet sites have been mentioning the size of Elenin as being 80,000 km across. This is a scary, exaggerated number that may be referring to the size of Elenin’s coma – a hazy cloud of icy particles that surrounds a much, much smaller nucleus. The coma can be extensive but is insubstantial; it’s akin to icy cigarette smoke. Less than that, in fact… a comet’s coma and tail are even more of a vacuum than can be reproduced in a lab on Earth! In reality most comets have a nucleus smaller than 10km…that’s less than a billionth the mass of Earth (and a far cry from 80,000 km.) We have no reason to think that Elenin is any larger than this – it’s most likely smaller.
Ok, but how about the gravitational and/or magnetic effect of a comet passing by Earth? That’s surely got to do something, right? To Earth’s crust, or the tides? For the answer to that, I will refer to Don Yeomans, a researcher at NASA’s Near-Earth Object Program Office at JPL:
“Comet Elenin will not only be far away, it is also on the small side for comets. And comets are not the most densely-packed objects out there. They usually have the density of something akin to loosely packed icy dirt,” said Yeomans. “So you’ve got a modest-sized icy dirtball that is getting no closer than 35 million kilometers. It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean’s tides than comet Elenin ever will.”
“It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean’s tides than comet Elenin ever will.”
– Don Yeomans, NASA / JPL
And as far as the effect from Elenin’s magnetic field goes… well, there is no effect. Elenin, like all comets, doesn’t have a magnetic field. Not much else to say there.
But the claims surrounding Elenin have gone much further toward the absurd. That it’s going to encounter another object and change course to one that will cause it to impact Earth, or that it’s not a comet at all but actually a planet – Nibiru, perhaps? – and is on a collision course with our own. Or (and I particularly like this one) that alien spaceships are trailing Elenin in such a way as to remain undetected until it’s too late and then they’ll take over Earth, stealing our water and natural resources and turning us all into slaves and/or space munchies… or however the stories go. (Of course the government and NASA and Al Gore and Al Gore’s hamster are all in cahoots and are withholding this information from the rest of us. That’s a given.) These stories are all just that – stories – and have not a shred of science to them, other than a heaping dose of science fiction.
“We live in nervous times, and conspiracy theories and predictions of disaster are more popular than ever. I like to use the word cosmophobia for this growing fear of astronomical objects and phenomena, which periodically runs amuck on the Internet. Ironically, in pre-scientific times, comets were often thought to be harbingers of disaster, mostly because they seemed to arrive unpredictably – unlike the movements of the planets and stars, which could be tracked on a daily and yearly basis.”
– David Morrison, planetary astronomer and senior scientist at NASA’s Ames Research Center
The bottom line is this: Comet C/2010 X1 Elenin is coming, and it will pass by Earth at an extremely safe distance – 100 times the distance from Earth to the Moon. It will not be changing direction between now and then, it will not exert any gravitational effect on Earth, its magnetic field is nonexistent and there are no Star Destroyers cruising in its wake. The biggest effect it will have on Earth is what we are able to learn about it as it passes – after all, it is a visitor from the far reaches of our solar system and we won’t be seeing it again for a very, very long time.
I’m sure we’ll have found something else to be worried about long before then.
“This intrepid little traveler will offer astronomers a chance to study a relatively young comet that came here from well beyond our solar system’s planetary region. After a short while, it will be headed back out again, and we will not see or hear from Elenin for thousands of years. That’s pretty cool.”
– Don Yeomans
For more information about Elenin, check out this JPL news release featuring Don Yeomans, and there’s a special public issue of Astronomy Beat, a newsletter from the Astronomical Society of the Pacific, that features David Morrison of NASA’s Ames Research Center discussing many of the misconceptions about Elenin.
An updated chart of Elenin’s orbit and statistics can be viewed here.
The SOHO spacecraft coronagraph captured a sun-diving comet on May 10th and 11th that met its demise as it plunged into the Sun just as Old Sol released a huge flare. The two events were coincidental and not related, but spectacular to see.
Ancient comets may have created Titan's nitrogen-rich atmosphere
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Titan is a fascinating world to planetary scientists. Although it’s a moon of Saturn it boasts an opaque atmosphere ten times thicker than Earth’s and a hydrologic cycle similar to our own – except with frigid liquid methane as the key component instead of water. Titan has even been called a living model of early Earth, even insofar as containing large amounts of nitrogen in its atmosphere much like our own. Scientists have wondered at the source of Titan’s nitrogen-rich atmosphere, and now a team at the University of Tokyo has offered up an intriguing answer: it may have come from comets.
Traditional models have assumed that Titan’s atmosphere was created by volcanic activity or the effect of solar UV radiation. But these rely on Titan having been much warmer in the past than it is now…a scenario that Cassini mission scientists don’t think is the case.
New research suggests that comet impacts during a period called the Late Heavy Bombardment – a time nearly 4 billion years ago when collisions by large bodies such as comets and asteroids were occurring regularly among worlds in our solar system – may have generated Titan’s nitrogen atmosphere. By firing lasers into ammonia-and-water-ice material similar to what would have been found on primordial Titan, researchers saw that nitrogen was a typical result. Over the millennia these impacts could have created enough nitrogen to cover the moon in a dense haze, forming the thick atmosphere we see today.
“We propose that Titan’s nitrogen atmosphere formed after accretion, by the conversion from ammonia that was already present on Titan during the period of late heavy bombardment about four billion years ago.”
– Yasuhito Sekine et al., University of Tokyo, Japan
This model, if true, would also mean that the source of Titan’s nitrogen would be different than that of other outer worlds, like Pluto, and even inner planets like our own.
Top image is a combination of a color-composite of Titan made from raw Cassini data taken on October 12, 2010 and a recolored infrared image of the comet Siding Spring, taken by NASA’s WISE observatory on January 10, 2010. The background stars were also taken by the Cassini orbiter. NASA / JPL / SSI and Caltech/UCLA. Edited by J. Major.
Note: the image at top is not scientifically accurate…the comet’s tail would be, based on the lighting of Titan, pointing more to the ten o’clock position as well as forward toward the viewer’s left shoulder. This would make it ‘look’ as if it were going the opposite direction though, away from Titan, and so I went with the more immediately decipherable version seen here. To see a more “realistic” version, click here.
Stardust-NExT photographed jets of gas and particles streaming from Comet Tempel 1 during Feb 14, 2011 flyby. The raw image taken during closest approach has been extensively enhanced by outside analysts to visibly show the jets. Annotations show the location of the jets and the man-made crater created by a projectile hurled by NASA’s prior Deep Impact mission in 2005. Credit: NASA/JPL-Caltech/University of Maryland/Post process and annotations by Marco Di Lorenzo/Kenneth Kremer
[/caption]Farewell Stardust-NExT !
Today marks the end to the final chapter in the illustrious saga of NASA’s Stardust-NExT spacecraft, a groundbreaking mission of cometary exploration.
Mission controllers at NASA’s Jet Propulsion Laboratory commanded the probe to fire the main engines for the very last time today at about 7 p.m. EDT (March 24). The burn will continue until the spacecraft entirely depletes the tiny amount of residual fuel remaining in the propellant tanks. The Stardust probe is now being decommissioned and is about 312 million kilometers away from Earth.
This action will effectively end the life of the storied comet hunter, which has flown past an asteroid (Annefrank), two comets (Wild 2 and Tempel 1) and also returned the first ever pristine samples of a comet to Earth for high powered analysis by the most advanced science instruments available to researchers.
NASA’s Stardust space probe completed her amazing science journey on Feb. 14, 2011 by streaking past Comet Tempel 1 at 10.9 km/sec, or 24,000 MPH and successfully sending back 72 high resolution images of the comets nucleus and other valuable science data. Tempel 1 became the first comet to be visited twice by spacecraft from Earth.
During the Feb. 14, 2011 flyby of Comet Tempel 1, Stardust-NExT discovered the man-made crater created back in 2005 by NASA’s Deep Impact mission and also imaged gas jets eminating from the comet. My imaging partner Marco Di Lorenzo and myself prepared two posters illustrating the finding of the jets and the Deep Impact crater included in this article.
6 Views of Comet Tempel 1 and Deep Impact crater from Stardust-NExT spacecraft flyby on Feb. 14, 2011. Arrows show location of man-made crater created in 2005 by NASA’s prior Deep Impact comet smashing mission and newly imaged as Stardust-NExT zoomed past comet in 2011.
The images progress in time during closest approach to comet beginning at upper left and moving clockwise to lower left. Credit: NASA/JPL-Caltech/University of Maryland/Post process and annotations by Marco Di Lorenzo/Kenneth Kremer
The rocket burn will be the last of some 2 million rocket firings all told since the Stardust spacecraft was launched back in 1999. Over a dozen years, Stardust has executed 40 major flight path maneuvers and traveled nearly 6 billion kilometers.
The rocket firing also serves another purpose as a quite valuable final contribution to science. Since there is no fuel gauge on board or precise method for exactly determining the quantity of remaining fuel, the firing will tell the engineers how much fuel actually remains on board.
To date the team has relied on several analytical methods to estimate the residual fuel. Comparing the results of the actual firing experiment to the calculations derived from estimates will aid future missions in determining a more accurate estimation of fuel consumption and reserves.
“We call it a ‘burn to depletion,’ and that is pretty much what we’re doing – firing our rockets until there is nothing left in the tank,” said Stardust-NExT project manager Tim Larson of NASA’s Jet Propulsion Laboratory in Pasadena, Calif in a statement. “It’s a unique way for an interplanetary spacecraft to go out. Essentially, Stardust will be providing us useful information to the very end.”
Just prior to the burn, Stardust will turn its medium gain antenna towards Earth and transmit the final telemetry in real time. Stardust is being commanded to fire the thrusters for 45 minutes but the team expects that there is only enough fuel to actually fire for up to perhaps around ten minutes.
On March 24, at about 4 p.m. PDT, four rocket motors on NASA's Stardust spacecraft, illustrated in this artist's concept, are scheduled to fire until the spacecraft's fuel is depleted. Image credit: NASA/JPL-Caltech
As its final act, the transmitters will be turned off (to prevent accidental transmissions to other spacecraft), all communications will cease and that will be the end of Stardust’s life.
With no more fuel available, the probe cannot maintain attitude control, power its solar array or point its antenna. And its far enough away from any targets that there are no issues related to planetary protection requirements.
“I think this is a fitting end for Stardust. It’s going down swinging,” Larson stated in the press release.
Read more about the Stardust-NExT Flyby and mission in my earlier stories here, here, here, here, here, here and here
Relive the Feb. 14 Flyby of Comet Tempel 1 in this movie of NASA/JPL images
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.Stardust-NExT location on March 11, 2011 just prior to farewell transmission. Credit: NASA/JPL
News conference held Feb. 15 following the flyby of comet Tempel 1 by the Stardust-NExT spacecraft on Valentine's Day, Feb. 14. The spacecraft's closest approach was a distance of 112 miles. Participants are: Ed Weiler, NASA's associate administrator, Science Mission Directorate, Washington; Joe Veverka, Stardust-NExT principal investigator, Cornell University; Tim Larson, Stardust-NExT project manager, NASA's Jet Propulsion Laboratory, Pasadena, Calif.; Don Brownlee, Stardust-NExT co-investigator, University of Washington, Seattle; and Pete Schultz, Stardust-NExT co-investigator, Brown University.
As Stardust-Next was racing past Comet Tempel at 9.8 km/sec, or 24,000 MPH, it encountered a hail of bullet like particles akin to a warplane meeting the fury of armed resistance fighters which potentially could have utterly destroyed the probe.
NASA has released a cool sound track of the sounds of thousands of cometary dust particles pelting Stardust-NExT. The audio was recorded by an instrument aboard the spacecraft called the Dust Flux Monitor which measures sound waves and electrical pulses from dust impacts.
Telemetry downlinked after the Feb. 14 flyby indicates the spacecraft flew through waves of disintegrating cometary particles.
“The data indicate Stardust went through something similar to a B-17 bomber flying through flak in World War II,” says Don Brownlee, Stardust-NExT co-investigator from the University of Washington in Seattle.
I contacted co-investigator Don Brownlee for further insight into the sounds and sights of the Tempel 1 flyby.
“The 12 biggest particles penetrated the centimeter thick front honeycomb plate of the whipple meteoroid shield and were detected with the Dust Flux Monitor Instrument,“ Brownlee told me. “The instrument had two type of sensors made in a collaboration between the University of Chicago and the University of Kent in the UK.
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The shielding was installed to protect Stardust from the hail of cometary particles during its prior flyby at Comet Wild 2 in 2004. Brownlee was the Principal Investigator for Stardust during its original mission at Wild 2.
I asked Brownlee if the shields were essential to the spacecraft surviving the Tempel 1 flyby ?
“Yes,’ he replied.
“A total of approximately 5,000 particle impacts were detected,” Brownlee said. This was over a period of about 11 minutes during closest approach. The movie is in real time and is a visual representation of the sounds. It covers just a portion of the flyby.
“Like at Wild 2, the particles came out in bursts and clumps. The Tempel 1 flyby, the Wild 2 flyby and the recent imaging of Comet Hartley confirm that fragmenting. Dust and ice clods are commonly released into space by comets.”
“The biggest at Wild 2 was about 0.5 cm and this time at Tempel 1 they were probably a bit bigger. The penetrating impacts at Tempel 1 were about twice what they were at Wild 2 ….. Also about twice as fast!”
“The data indicate Stardust went through something similar to a B-17 bomber flying through flak in World War II,” said Don Brownlee, Stardust-NExT co-investigator from the University of Washington in Seattle. “Instead of having a little stream of uniform particles coming out, they apparently came out in chunks and crumbled.”
To my eye, I was surprised that the flyby images seemed to surpass those at Wild 2. Brownlee agreed.
“I was surprised,” said Brownlee. “The team did a terrific job and the images are better than before. Tempel is a little closer to the sun, the flyby was a little closer, the pictures were taken at a much higher rate and the imaging team put in a great effort to plan the exposures and to clean up the camera before the encounter. The mirror was scanning at it’s maximum rate!”
Listen to the Stardust-NExT post flyby briefing
News conference held Feb. 15 following the flyby of comet Tempel 1 by the Stardust-NExT spacecraft on Valentine’s Day, Feb. 14. The spacecraft’s closest approach was a distance of 112 miles. Participants are: Ed Weiler, NASA’s associate administrator, Science Mission Directorate, Washington; Joe Veverka, Stardust-NExT principal investigator, Cornell University; Tim Larson, Stardust-NExT project manager, NASA’s Jet Propulsion Laboratory, Pasadena, Calif.; Don Brownlee, Stardust-NExT co-investigator, University of Washington, Seattle; and Pete Schultz, Stardust-NExT co-investigator, Brown University.
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 by Ken Kremer to show additional detail.
Want to know what it feels like at close range to ride on a spaceship past a zooming comet that’s spewing dust and debris that could destroy you at any moment ?
Check out the movies (above & below) which gives you a front row seat at NASA’s newest ‘Comet Experience’. Hitch a ride on the rear of Stardust-NExT as it flew past Compet Tempel 1 at 9.8 km/sec, or 24,000 MPH.
The movie comprises the highest resolution images of the fleeting 8 minutes of the closest approach period that occurred between 8:35:26 p.m. to 8:43:08 p.m. PST on Feb. 14, 2011 (4:35:26 a.m. to 4:43:08 a.m. UTC, Feb. 15, 2011, according to the clock kept aboard the spacecraft).
Stardust started taking these the excellent quality photos at a distance of 2,462 kilometers (1,530 miles) away from the center of the comet and get to within 185 kilometers (115 miles). By the end of the movie, the spacecraft is 2,594 kilometers (1,611 miles) away from the center of the comet.
Think about it and the navigational precision required to pull off this feat. After a journey of near 6 billion kilometers (3.5 Billion miles) and 12 years, the highest quality science and images are captured in what amounts to an instant in time.
“And they did it with Math !”, exclaimed NASA Asspciate Admisistrator Ed Weiler at the post encounter briefing. Weiler exhorted school kids worldwide to study math and science if that want to accomplish great deeds.
Comet Tempel 1 was approximately 335 million kilometers (208 million miles) away from Earth and on the other side of the sun during the encounter. Tempel 1 is oblong in shape and has an average diameter of about 6 kilometers (4 miles).
The individual images are all online. Check out these alternate movie versions prepared by Dimitri Demeeter at Youtube and nasatech.net at the links below.
Here’s 1/10 sec with text
Here’s 1/4 sec with text
Here’s 1/2 sec with text
Here’s 1/10 sec w/o text
Here’s 1/2 sec w/o text
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Highlights from the Comet Tempel 1 Post Flyby briefing
more Stardust goodies coming up
Read more about the Stardust-NExT Flyby and mission in my earlier stories here, here, here, here and here
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.
