Comet Dust discovered for the first time on the Earth's surface

Credit: Earth and Planetary Science Letters, Volume 410, 15 January 2015, Pages 1–11.

A combined team of researchers from Japan and the U.S. has found particles of comet dust in ice extracted from the Antarctic, the first time comet dust particles have been found on the surface of the Earth.

In their paper published in the journal Earth and Planetary Science Letters, the researchers describe how they found the dust particles and what they've learned by analyzing them.

Finding samples of material from a comet is no easy feat, sending probes to them and back is a rare occurrence.

Because of that, scientists have taken to collecting samples floating about high in the Earth's the atmosphere, an approach that has its limitations as it involves using a sticky sheet that nets few of the dust particles and which leaves oils on the samples which are further dirtied by solvents meant to clean them.

In this latest effort, the researchers drilled down approximately 58 feet into the Antarctic snow and ice at a place called Tottuki Point.

When the ice was melted back in their lab, the researchers found, among other things, extremely tiny (10 to just over 60 micrometers) dust particles which they initially believed to be meteorite dust.

Subsequent analysis however showed that the particles (known as chondritic porous interplanetary dust particles) were a near perfect match to comet samples collected by NASA with its Stardust probe project and samples found in the atmosphere.

Back in 2010 a team from France studying Antarctic snow reported finding what they believed to be comet particles, but this new finding is the first to report finding comet dust on the surface of the Earth.

Prior to the finding, scientists had believed that tiny dust particles would never survive the trip through the atmosphere, much less the harsh conditions once they landed.

The finding is exciting because it will mean scientists will be able to get their hands on more samples than they could with atmospheric collection.

The first ice chunks already have given up more than 40 of the dust particles.

Space scientists are eager to learn more about comets as they are believed to represent some of the oldest objects out in space, learning more about them should reveal more about the origins of our solar system, and perhaps whether they are the seeders of life on our planet, as some have come to believe.

More information: Cometary dust in Antarctic ice and snow: Past and present chondritic porous micrometeorites preserved on the Earth's surface, Earth and Planetary Science Letters, Volume 410, 15 January 2015, Pages 1–11. www.sciencedirect.com/science/… ii/S0012821X14007031

ESA Rosetta mission: Philae lander - the sound of a Comet Touchdown

Image credit: ESA/ATG medialab – Audio file credit: ESA /Rosetta /Philae /SESAME /DLR

Sensors in the feet of Rosetta’s lander Philae have recorded the sound of touchdown as it first came into contact with Comet 67P/Churyumov-Gerasimenko. 

The instrument, SESAME-CASSE, was turned on during the descent and clearly registered the first touchdown as Philae came into contact with the comet, in the form of vibrations detected in the soles of the lander’s feet.

Focus on SESAME. Sensors are located in the three feet as well as in the units of the APXS (centre) and MUPUS-Pen (to the upper right of centre) instruments. Credits: ESA/ATG medialab

SESAME is the lander’s Surface Electrical Sounding and Acoustic Monitoring Experiment, and comprises three suites of instruments:

• CASSE – the Comet Acoustic Surface Sounding Experiment, which allows mechanical parameters of the surface to be deduced, along with details of the structure of the subsurface;
• DIM – the Dust Impact Monitor, which measures properties of impacting comet grains;
• PP – the Permittivity Probe, which determines one of the key electrical properties of the material beneath Philae, which is linked to the water ice content of the surface.

Klaus Seidensticker from the DLR Institute of Planetary Research says: “Our data record the first touchdown and show that Philae’s feet first penetrated a soft surface layer – possibly a dust layer – several centimetres thick until they hit a hard surface – probably a sintered ice-dust layer – a few milliseconds later.”

Most Water in Lunar Soil generated by Solar Wind

This is a composite image of the lunar nearside taken by the Lunar Reconnaissance Orbiter in June 2009, note the presence of dark areas of maria on this side of the moon. Credit: NASA

A pair of researchers with the Sorbonne Universités, Muséum National d'Histoire Naturelle, has determined that most of the water in the soil on the surface of the moon was formed due to protons in the solar wind colliding with oxygen in lunar dust, rather than from comet or meteorite impacts.

In their paper published in Proceedings of the National Academy of Sciences, Alice Stephant and François Robert describe their study and the results they found.

When NASA astronauts brought back soil and rock samples from the moon, it was assumed by most in the scientific community that everything they found was dry, that there was no water in any of it.

Subsequent analysis using newer techniques has revealed that not only is there water beneath the surface in some places, but the dust on the surface also has small amounts as well.

Once this became known, most scientists assumed the water got there due to comet or meteorite impacts, in this new effort, the research pair suggests that conventional thinking is wrong once again and that the water, at least in the surface dust, comes about due to the impact of solar wind on tiny dust particles.

In studying tiny grains of lunar soil samples, the researchers found that the reduction of oxygen from silicates in the soil by protons from the solar wind was almost certainly the means by which the water was generated.

They came to that conclusion through determining the lithium isotope ratio in the samples (plagioclase rock found on the surface of the moon) which gave the isotope ratio for the hydrogen, from that they were able to calculate the deuterium-hydrogen ratio which they compared to the amount of water actually in the granule sample.

They found that on average, the granules contained just 15 percent water from somewhere else (presumably comets or meteorites) leaving the rest to have been formed due to the solar wind interaction. They note also that for some samples, all of the water was due to solar wind interaction.

The duo is quick to point out that their conclusions only relate to water found on the surface of the moon, where the water below the surface came from is still up for conjecture.

More information: "The negligible chondritic contribution in the lunar soils water" - Alice Stephant, PNAS, DOI: 10.1073/pnas.1408118111

ESA Satellite Sentinel-1A maps out Napa Valley earthquake

A radar interferogram from Sentinel-1A showing how the ground moved in the Napa Valley earthquake. 

Each coloured fringe is caused by a change in distance between the ground and the satellite of about 3cm. 

The extent of the ground deformation in the interferogram shows that the fault slip which occurred in this earthquake continues further north than the extent of the mapped rupture at the surface. 

Credit: Copernicus data (2014) /ESA/PPO.labs-Norut–COMET-SEOM Insarap study

Scientists have used a new Earth-observation satellite called Sentinel-1A to map the ground movements caused by the earthquake that shook up California's wine-producing Napa Valley on 24 August 2014.

This is the first earthquake to be mapped by the European Space Agency's (ESA) new satellite and demonstrates the capabilities of the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET) in analysing its observations quickly.

COMET Director, Professor Tim Wright, from the School of Earth and Environment at the University of Leeds, said: "This successful demonstration of Sentinel-1A marks the beginning of a new era for our ability to map earthquakes from space.

COMET scientists are building a system that will routinely provide results for all continental earthquakes, as well as mapping the slow warping of the ground surface that leads to earthquakes."

Professor Andy Hooper, a member of the COMET team from the School of Earth and Environment at the University of Leeds, added: "This satellite represents a sea change in the way we will be able to monitor catastrophic events, such as earthquakes and volcanic eruptions, due to its systematic observation strategy."

Sentinel-1A was launched on 3 April 2014, but it only reached its final operational orbit on 7 August. The pre-earthquake image was acquired on that day.

By comparing it with an image acquired on 31 August, COMET collaborators Dr Yngvar Larsen, from the research institute Norut in Norway, and Dr Petar Marinkovic, from PPO.labs in the Netherlands, created a map of the surface deformation, called an 'interferogram', caused by the magnitude 6.0 earthquake.

The images are being used by scientists on the ground to help them map the surface rupture.

Austin Elliott, a PhD student at the University of California, Davis, who has been among the team mapping the earthquake rupture on the ground said: "The data from satellites are invaluable for completely identifying the surface break of the earthquake, deformation maps from satellite imagery guide us to places where rupture has not yet been mapped."

Although the Sentinel-1 satellite system, which will also include the future Sentinel-1B satellite, is still being tested and commissioned, ESA was able to ensure data covering the earthquake were acquired, and provide this to the science team rapidly.

When the Sentinel-1 constellation is fully operational, the average time delay between an earthquake and a radar acquisition will only be a few days, which will mean the results will also be useful for helping with humanitarian responses on the ground.

The interferogram clearly confirms that the West Napa Fault was responsible for the earthquake. This fault had not been identified as being particularly hazardous prior to the event.

ESA Rosetta Spacecraft Snaps Amazing 3D View of Comet 67P

Break out your red and blue 3D glasses. It's time to examine the nooks and crannies of a comet in three dimensions.

The European Space Agency's Rosetta probe snapped the two amazing images that were spliced together to create this 3D picture of its target, Comet 67P/Churyumov-Gerasimenko, after arriving at the deep space object last week.

The picture of the comet seems to pop off the page when viewed through 3D glasses. Rosetta snapped the two photos on Aug. 7 when the spacecraft was about 65 miles (104 kilometers) away from the comet.

You can see a flyover video of the comet here.

"Peer over cliffs and onto the boulder-strewn 'neck' region, marvel at the layers in the exposed cliff face, and ponder the formation of the numerous crater-like depressions in this amazing 3D view of Comet 67P," ESA officials wrote in an image description.

The space agency also released the separate images used to create the 3D view.

The up-close-and-personal photos show house-sized boulders and seemingly smooth areas on the oddly shaped comet's "head," "neck" and "body."

The images aren't just for entertainment. Rosetta's mission controllers are scoping out good places for the Philae lander, another spacecraft currently housed within Rosetta, to touch down on the 2.5-mile-wide (4 km) comet in November.

Rosetta's photos have already shown that the comet isn't the usual "potato" shape that many people were expecting it to be, according to ESA.

Ground controllers have already started checking out some interesting spots that they could land Philae, but they will choose up to five possible landing sites during a meeting from Aug. 22 to 24.

"The physical nature of the site is also an important factor: are there hazards such as large boulders or deep crevasses on the surface?" ESA officials wrote in a mission description.

"Is the topography of the landing site suitable for the science experiments?"

Data collected by Rosetta's instruments will help determine the best place to land in the months to come, allowing ESA officials to figure out the gravity and rotation of the comet to ensure Philae gets to the surface safely once released.

Rosetta has consistently beamed back amazing images of the comet since its arrival at Comet 67P/C-G on August 6.

A Rosetta photo, taken on Aug. 12, shows the comet's weird shape emerging from shadow.

ESA Rosetta: First Comet Close-Ups Reveal a 'Scientific Disneyland'

Rosetta spacecraft's OSIRIS narrow-angle camera obtained this close-up detail of a smooth region on the "base" of the "body" section of comet 67P/Churyumov-Gerasimenko on August 6, 2014.

Credit: ESA/Rosetta/MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

It's only been a few hours since Europe's Rosetta spacecraft arrived at a comet in deep space, but the robotic probe is already beaming incredible close-up photos of its target.



The latest images from the Rosetta probe reveal details on the surface of Comet 67P/Churyumov-Gerasimenko like never before.

House-size boulders can be seen on the surface of the comet, and the "neck," "body" and "head of the dirty snowball are all on stark display. T

he photos were taken when Rosetta was about 81 miles (130 kilometers) away from the comet.

"We've arrived. Ten years we've been in the car waiting to get to scientific Disneyland, and we haven't even gotten out of the car yet and look at what's outside the window," Mark McCaughrean, senior scientific adviser with the ESA's Directorate of Science and Robotic Exploration, said during a webcast of the Rosetta's comet arrival today (Aug. 6). "It's just astonishing."

Rosetta spacecraft's OSIRIS narrow-angle camera obtained this close-up detail of Comet 67P/Churyumov-Gerasimenko on August 6, 2014. The comet’s "head" lies at the left, casting shadows onto the "neck" and "body" to the right.

Credit: ESA/Rosetta/MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

And McCaughrean wasn't alone in his enthusiasm at Rosetta's mission operations center in Darmstadt, Germany.

"This is a very, very emotional moment," Holger Sierks, the principal investigator for Rosetta's OSIRIS instrument, said during the webcast.

"You see a lot of detail coming out here. We see the bright areas. We see the head. We see the depression and a lot of stuff laid out there. We see the sides, the body, the lower body of the nucleus and a lot of detail."

Both Rosetta and Comet 67P/C-G are flying in tandem at about 251 million miles (405 million km) from Earth.

Rosetta set off on its quest to link up with the comet in 2004, traveling about 4 billion miles (6.4 billion km) before making its historic rendezvous with the comet this morning.

While today does mark an event 10 years in the making, it is just the beginning of the mission for many ESA scientists.

ESA officials still need to find a suitable landing spot for the Philae lander, a robotic craft that hitched a ride with Rosetta to the comet.

Philae (named for an obelisk found on an island in the Nile River) is designed to touch down on the surface of Comet 67P/G-C to learn more about the composition and properties of the 2.5-mile-wide (4 km) comet.

German Aerospace Center's portal DLR tweeted this photo showing the "face" on Comet 67P/Churyumov-Gerasimenko, Aug. 6, 2014.

Credit: DLR

Mission controllers will now put Rosetta into a triangular orbit around Comet 67P/Churyumov-Gerasimenko (67P/C-G) before moving the probe closer to the comet.

Eventually, Rosetta will move into an even tighter circular orbit to release its lander down to the comet's surface in November.

The $1.7 billion (1.3 billion euros) Rosetta mission is expected to end in December 2015 when the spacecraft moves away from Comet 67P/C-G. Before the end of the mission, however, Rosetta will accompany the comet as it makes its closest pass of the sun in its 6.5-year orbit.

During that close pass, the probe should be able to observe the comet in a very active state.

"After landing, Rosetta will continue to accompany the comet until its closest approach to the sun in August 2015 and beyond, watching its behaviour from close quarters to give us a unique insight and real-time experience of how a comet works as it hurtles around the sun," Matt Taylor, Rosetta project scientist, said in a statement.

NASA Neowise: A comet that looked like an asteroid

Comet C/2013 UQ4 (Catalina) appeared to be a highly active comet one day past perihelion on July 7, 2014.

Credit: NASA/JPL-Caltech

Comet C/2013 UQ4 (Catalina) has been observed by NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft just one day after passing through its closest approach to the sun.

The comet glows brightly in infrared wavelengths, with a dust tail streaking more than 62,000 miles (100,000 kilometers) across the sky.

Its spectacular activity is driven by the vapourisation of ice that has been preserved from the time of planet formation 4.5 billion years ago.

"The tail forms a faint fan as the smaller dust particles are more easily pushed away from the sun by the radiation pressure of the sunlight," said James Bauer, researcher at NASA's Jet Propulsion Laboratory in Pasadena, California.

C/2013 UQ4 takes more than 450 years to orbit the sun once and spends most of its time far away at very low temperatures.

Its orbit is also retrograde, which means that the comet moves around the sun in the opposite direction to the planets and asteroids.

The comet was originally thought to be an asteroid, as it appeared inactive when discovered by the Catalina Sky Survey on October 23, 2013.

NEOWISE also observed the comet to be inactive on New Year's Eve, 2013, but since then the comet has become highly active, allowing astronomers around the world to observe it.

The comet's activity should decline as it once again returns to the cold recesses of space.

ESA Rosetta: Burning down to 67P/C-G comet rendezvous

ESA Rosetta's target comet, 67P/Churyumov-Gerasimenko, is about 4 km wide. 

Here it is presented alongside some of Earth's landmarks. 

Image courtesy ESA.

It's burn week in space again, and Wednesday, 2 July, marks the start of a fresh set of four orbit correction manoeuvres (OCMs), referred to as the "Far Approach Trajectory" burns.

These will be somewhat smaller than those previous but will be conducted weekly, rather than fortnightly. First, a quick recap to bring you up to date.

On 7 May, Rosetta began a series of ten OCMs designed to reduce its speed with respect to comet 67P/C-G by about 775 m/s.

The first, producing just 20 m/s delta-v ("change in velocity"), was done as a small test burn, as it was the first use of the spacecraft's propulsion system after waking from hibernation on 20 January. The system worked fine!

The following three, referred to by the Rosetta mission team as the "Near Comet Drift" (NCD) set (and nicknamed here in the blog as "The Big Burns"), took place every two weeks starting 21 May.

These three also ran beautifully and delivered 289.6, 269.5 and 88.7 m/s in delta-v, respectively. They were, in terms of run time, some of the longest manoeuvres ever conducted by an ESA spacecraft.

Thus the first four burns have already delivered 667.8 of the roughly 775 m/s needed to slow down to a relative velocity smaller than 1 m/s when we meet the comet on 6 August.



"The OCMs conducted so far have delivered more or less the exact amount of delta-v needed; we've seen small over-performances of less than a percent, meaning that no replanning of subsequent OCMs has, so far, been necessary," says Sylvain Lodiot, Rosetta Spacecraft Operations Manager.

Another aspect of the burns to date is the fact that, if a burn did not take place as planned (due to any sort of glitch on board Rosetta or on the ground), the team had a week (or more) in which to correct the problem and re-do the burn, tight, but doable in terms of technology and team-planning workload.

This is about to change.

Four Fatties
The next four burns are designated as the "Far Approach Trajectory" (FAT) manoeuvres, and since your blog editors can't think of any better nickname (and despite them being much smaller than the three Big Burns), we'll just call them the "Four Fatties".

Fatty1 gets underway on 2 July at 14:05:57 CEST (12:05:57 UTC), should run for 1 hr:33mins:13secs and is set to deliver a delta-v of 58.7 m/s (the next three, on 9, 16 and 23 July, are planned for 25.8, 11.0 and 4.8 m/s, respectively).

(The Four Fatties will be followed by two final CAT for Close Approach Trajectory - burns, for the total of 10 OCMs; details on these later.)

But while the required delta-v's are getting smaller, so, too, are the reaction times available to the Rosetta team if anything goes wrong with a burn.

"The next four FAT burns, in particular, are critical," says Sylvain.

If any one burn is delayed, we will have a window of just a few days in which to react, fix whatever caused the problem, replan the burn - which would invariably require even more fuel - and then carry it out."

It goes without saying that handling any such replanned burn would require team work and expertise of the highest calibre.

But this is all theoretical for now; today Rosetta is working nominally and no one expects problems with the propulsion system for the Four Fatties.

The rest of the spacecraft's systems - including power, thermal, attitude and orbit control, data handling and communications, are operating as expected.

Read the full article here

ESA Rosetta 67P/Churyumov-Gerasimenko: Comet 'sweats' two glasses of water per second

This artist's impression shows the Rosetta orbiter at comet 67P/Churyumov-Gerasimenko. The image is not to scale. 

Credit: ESA/ATG Medialab

Unprecedented measurement of a deep-space comet has found the icy body to be losing about two small glasses of water every second, the European Space Agency (ESA) said on Monday.

ESA's Rosetta, made the measurements on June 6, when it aimed a microwave sensor at 67P/Churyumov-Gerasimenko, on which it will land a probe in August after a 10-year space trek.

It found the comet lost 300 millilitres (10.5 fluid ounces) of water in vapour every second, even though it was still 583 million kilometres (364 million miles) from the Sun, which it orbits.

The measurement is a technical feat, carried out when Rosetta was still 350,000 km from the comet.

It also indicates that the Sun starts to have a visible impact on comets even when the wanderers are still at a great distance, ESA said in a press release.

"We always knew we would see water vapour outgassing from the comet, but we were surprised at how early we detected it," said Sam Gulkis of NASA's Jet Propulsion Laboratory, who is in charge of Rosetta's MIRO microwave instrument.

"At this rate, the comet would fill an Olympic-size swimming pool in about 100 days but, as it gets closer to the Sun, the... production rate will increase significantly."

Comets follow elliptical paths around the Sun, spewing spectacular tails of gas, dust and frozen water as heat from the hot star causes surface ice to evaporate.

These tails, illuminated in the Sun's rays, are what makes comets so spectacular when seen from Earth.

Launched in 2004, Rosetta is designed to team up with "67P" in August and follow it on its journey around the Sun.

In November, it will send down a 100-kilogramme (220-pound) refrigerator-sized lander, Philae, which will hook itself to the comet's surface and carry out scientific experiments.

On Monday, the spacecraft was within 72,000 km of its destination, ESA said.

Six manoeuvres will be needed over the coming weeks to ensure that it arrives at a distance of just 100 km from the rock on August 6.

The comet, with Rosetta as its escort, will be at its closest to the Sun in August 2015, when it will be between the orbits of Earth and Mars.

Comets are sometimes called "dirty snowballs"—but cosmologists say their primeval mix of ice and dust forms time capsules that offer insights into how the Solar System formed 4.5 billion years ago.

Some scientists believe comets may have brought much of the water in today's oceans and possibly complex molecules that kickstarted life on Earth.

ESA Rosetta Mission: Waking up from Hibernation

Philae landing on comet

Next year, on 20 January, after 957 days of hibernation in deep space, ESA’s comet-chasing Rosetta spacecraft is set to wake up automatically en route to the destination it has been travelling towards for nearly a decade.

In preparation for the critical activation and the challenges that lie ahead for Rosetta, members of the media are invited to a briefing by ESA’s science and mission control experts and partners on Tuesday, 10 December, 10:00–12:30 CET, at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany.

The 20 January milestone will mark the start of an intensive year as Rosetta draws steadily closer to comet Churyumov–Gerasimenko ahead of rendezvous in August.

After extensively mapping the comet’s surface, it will dispatch the lander Philae in November for close-up study of the nucleus.

Rosetta will then follow the comet on its journey through the inner Solar System, monitoring the ever-changing conditions as it warms up heading towards its closest approach to the Sun, in August 2015.

Rosetta’s main objective is to help understand the origin and evolution of the Solar System, in particular investigating the role that comets may have played in seeding Earth with water, and perhaps even life.

NAU-led team discovers comet hiding in plain sight

Don Quixote's coma and tail (left) as seen in infrared light by NASA's Spitzer Space Telescope. After image processing (right), the tail is more apparent. 

Image courtesy NASA/JPL-Caltech/DLR/NAU

For 30 years, a large near-Earth asteroid wandered its lone, intrepid path, passing before the scrutinizing eyes of scientists while keeping something to itself: 3552 Don Quixote, whose journey stretches to the orbit of Jupiter, now appears to be a comet.

The discovery resulted from an ongoing project led by researchers at Northern Arizona University using the Spitzer Space Telescope.

Through a lot of focused attention and a little bit of luck, they found evidence of cometary activity that had evaded detection for three decades.

"Its orbit resembled that of a comet, so people assumed it was a comet that had gotten rid of all its ice deposits," said Michael Mommert, a post-doctoral researcher at NAU who was a Ph.D. student of professor Alan Harris at the German Aerospace Center (DLR) in Berlin at the time the work was carried out.

What Mommert and an international team of researchers discovered, though, was that Don Quixote was not actually a dead comet-one that had shed the carbon dioxide and water that give comets their spectacular tails.

Instead, the third-biggest near-Earth asteroid out there, skirting Earth with an erratic, extended orbit, is "sopping wet," said NAU associate professor David Trilling.

The implications have less to do with potential impact, which is extremely unlikely in this case, and more with "the origins of water on Earth," Trilling said.

Comets may be the source of at least some of it, and the amount on Don Quixote represents about 100 billion tons of water-roughly the same amount found in Lake Tahoe.

Mommert said it's surprising that Don Quixote hasn't been depleted of all of its water, especially since researchers assumed that it had done so thousands of years ago but finding evidence of CO2, and presumably water, wasn't easy.

During an observation of the object using Spitzer in August 2009, Mommert and Trilling found that it was far brighter than they expected. "The images were not as clean as we would like, so we set them aside," Trilling said.

Much later, though, Mommert prompted a closer look, and partners at the Harvard-Smithsonian Center for Astrophysics found something unusual when comparing infrared images of the object: something, that is, where an asteroid should have shown nothing.

The "extended emission," Mommert said, indicated that Don Quixote had a coma-a comet's visible atmosphere-and a faint tail.

Mommert said this discovery implies that carbon dioxide and water ice also might be present on other near-Earth objects.

This study confirmed Don Quixote's size and the low, comet-like reflectivity of its surface. Mommert is presenting the research team's findings this week at the European Planetary Space Conference in London.

Near-Earth asteroid is really a comet

The image displays Don Quixote's orbit. Credit: Josh Emery

Some things are not always what they seem—even in space. For 30 years, scientists believed a large near-Earth object was an asteroid.

Now, an international team including Joshua Emery, assistant professor of earth and planetary sciences at the University of Tennessee, Knoxville, has discovered it is actually a comet.

Called 3552 Don Quixote, the body is the third largest near-Earth object—mostly rocky bodies, or asteroids, that orbit the Sun in the vicinity of Earth.

About 5 percent of near-Earth objects are thought to be "dead" comets that have shed all the water and carbon dioxide in the form of ice that give them their coma—a cloud surrounding the comet nucleus—and tail.

The team found that Don Quixote is neither. It is, in fact, an active comet, thus likely containing water ice and not just rocks.

The finding will be presented at the European Planetary Science Congress 2013 in London, Sept. 10. The discovery could hold implications for the origin of water on Earth.

Joshua Emery

"Don Quixote has always been recognized as an oddball," said Emery. "Its orbit brings it close to Earth, but also takes it way out past Jupiter."

"Such a vast orbit is similar to a comet's, not an asteroid's, which tend to be more circular—so people thought it was one that had shed all its ice deposits."

Using the Spitzer Space Telescope operated by the Jet Propulsion Laboratory at the California Institute of Technology (CalTech) under contract with NASA, the team, led by Michael Mommert of Northern Arizona University, re-examined images of Don Quixote from 2009 when it was in the part of its orbit closest to the Sun, and found it had a coma and a faint tail.

Emery also reexamined images from 2004, when it was at its farthest distance from the sun, and determined that the surface is composed of silicate dust, which is similar to comet dust.

He also determined that Don Quixote did not have a coma or tail at this distance, which is common for comets because they need the sun's radiation to form the coma and the sun's charged particles to form the tail.

The researchers also confirmed Don Quixote's size and the low, comet-like reflectivity of its surface.

"The power of the Spitzer telescope allowed us to spot the coma and tail, which was not possible using optical telescopes on the ground," said Emery.

"We now think this body contains a lot of ice, including carbon dioxide and/or carbon monoxide ice, rather than just being rocky."

This discovery implies that carbon dioxide and water ice might be present within other near-Earth asteroids, as well.

It also may have implications for the origins of water on Earth as comets may be the source of at least some of it, and the amount on Don Quixote represents about 100 billion tons of water—roughly the same amount that can be found in Lake Tahoe, California's.

NASA Mars HiRISE: Camera reveals Two hundred impacts each year

This image shows one of many fresh impact craters spotted by the UA-led HiRISE camera, orbiting the Red Planet on board NASA's Mars Reconnaissance Orbiter since 2006. 

Credit: NASA /JPL-Caltech /MSSS /UA

Scientists using images from NASA's Mars Reconnaissance Orbiter, or MRO, have estimated that the planet is bombarded by more than 200 small asteroids or bits of comets per year forming craters at least 12.8 feet (3.9 meters) across.

Researchers have identified 248 new impact sites on parts of the Martian surface in the past decade, using images from the spacecraft to determine when the craters appeared.

The 200-per-year planet-wide estimate is a calculation based on the number found in a systematic survey of a portion of the planet.

The University of Arizona's High Resolution Imaging Science Experiment, or HiRISE camera, took pictures of the fresh craters at sites where before and after images had been taken.

This combination provided a new way to make direct measurements of the impact rate on Mars and will lead to better age estimates of recent features on Mars, some of which may have been the result of climate change.

"It's exciting to find these new craters right after they form," said Ingrid Daubar of the UA, lead author of the paper published online this month by the journal Icarus.

"It reminds you Mars is an active planet, and we can study processes that are happening today."

These asteroids or comet fragments typically are no more than 3 to 6 feet (1 to 2 meters) in diameter.

Space rocks too small to reach the ground on Earth cause craters on Mars because the Red Planet has a much thinner atmosphere.

MRO has been examining Mars with six instruments since 2006. Daubar is an imaging targeting specialist who has been on the HiRISE uplink operation s team from the very beginning.

She is also a graduate student in the UA's department of planetary science and plans on graduating with her doctorate in spring 2014.

Leslie Tamppari

"There are five of us who help plan the images that HiRISE will take over a two-week cycle," she explained.

"We work with science team members across the world to understand their science goals, help select the image targets and compile the commands for the spacecraft and the camera."

"The longevity of this mission is providing wonderful opportunities for investigating changes on Mars," said MRO Deputy Project Scientist Leslie Tamppari of NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Our Earth and its Moon Have a Common Water Source

The Moon's water did not come from comets but was already present on Earth 4.5 billion years ago, when a giant collision sent material from Earth to form the Moon, new research shows. 

Credit: NASA/JPL

Researchers used a multicollector ion microprobe to study hydrogen-deuterium ratios in lunar rock and on Earth.

Their conclusion: The Moon's water did not come from comets but was already present on Earth 4.5 billion years ago, when a giant collision sent material from Earth to form the Moon.

Water inside the Moon's mantle came from primitive meteorites, new research finds, the same source thought to have supplied most of the water on Earth. The findings raise new questions about the process that formed the Moon.

By showing that water on the Moon and on Earth came from the same source, this new study offers yet more evidence that the Moon's water has been there all along.

Alberto Saal

"The simplest explanation for what we found is that there was water on the proto-Earth at the time of the giant impact," said Alberto Saal, associate professor of Geological Sciences at Brown University and the study's lead author.

"Some of that water survived the impact, and that's what we see in the Moon."

Erik Hauri

The research was co-authored by Erik Hauri of the Carnegie Institution of Washington, James Van Orman of Case Western Reserve University, and Malcolm Rutherford from Brown and published online in Science Express.

Journal Reference:

1. Alberto E. Saal, Erik H. Hauri, James A. Van Orman, and Malcolm J. Rutherford. Hydrogen Isotopes in Lunar Volcanic Glasses and Melt Inclusions Reveal a Carbonaceous Chondrite Heritage. Science, 9 May 2013 DOI: 10.1126/science.1235142

NASA ESA Hubble Captures distant image of Comet ISON

Comet ISON may appear brighter than the full Moon around the time it approaches the Sun Nov. 28, but it is not yet visible to the naked eye. 

The Hubble Space Telescope snapped this image as ISON hurtles toward the sun at about 47,000 miles.

The NASA Hubble Space Telescope has given astronomers their clearest view yet of Comet ISON, a newly-discovered sun grazer comet that may light up the sky later this year, or come so close to the Sun that it disintegrates.

A University of Maryland-led research team is closely following ISON, which offers a rare opportunity to witness a comet's evolution as it makes its first-ever journey through the inner solar system.

Like all comets, ISON is a "dirty snowball" – a clump of frozen gases mixed with dust, formed in a distant reach of the solar system, traveling on an orbit influenced by the gravitational pull of the Sun and its planets.

ISON's orbit will bring it to a perihelion, or maximum approach to the Sun, of 700,000 miles on November 28, said Maryland assistant research scientist Michael S. Kelley.

Read Kelley's comprehensive blog on Comet ISON here

This image was made on April 10, when ISON was some 386 million miles from the Sun – slightly closer to the Sun than the planet Jupiter.

Comets become more active as they near the inner solar system, where the Sun's heat evaporates their ices into jets of gases and dust but even at this great distance ISON is already active, with a strong jet blasting dust particles off its nucleus.

As these dust particles shimmer in reflected sunlight, a portion of the comet's tail becomes visible in the Hubble image.

Russian Astronomers Discover Huge New Comet Approaching Solar System

Last year, Belarus and Russian astronomers Vitaly Nevsky(Belarus) and Artyom Novichonok(Russia), in the ISON-Kislovodsk observatory in Russia, discovered a new gigantic sungrazing comet that is currently approaching Earth.

C/2012 S1 or the ISON comet, which is expected to become brighter than the full moon, will be visible to the naked eye by late 2013.

The astronomers say that given the comet's unique orbit, its origin may be the Oort Cloud, a cluster of frozen rocks and ices surrounding the solar system, located almost a light-year from the Sun.

The comet is currently passing outside Jupiter, gaining speed and becoming brighter by the day. In September 2012, the Russian astronomers spotted what appeared to be a comet in images taken by a telescope that is part of the worldwide International Scientific Optical Network ( ISON), from which the object draws its name.

Thanks to ISON, astronomers can get images taken by remote telescopes in other countries, including in New Mexico, where a Russian automatic observatory is located.

The ISON comet never plunged into the inner solar system, and its surface darkened because of the impact of galactic particles. At the same time, the comet avoided being damaged by the so-called solar wind, which is not the case for the Moon, for example.

Sergei Smirnov, press secretary of the Pulkovo Astronomical Observatory in Russia, says that studying surface of the ISON comet may shed more light on evolution of the Universe.

"In the future, it would be good to have special space vehicles on standby so that they can approach such celestial objects, something that may finally come true given the ongoing development of air navigation," Smirnov says.

Thus far, Comet ISON has only been visible through powerful telescopes. In November 2013, heat from the sun will vaporize ices in the comet's body, creating what could be a spectacular tail that will be visible in Earth's night sky without telescopes or even binoculars from about October 2013 through January 2014.

ESA ESO Elst Pizarro: Strangest Comet

On August 7, 1996, Eric W. Elst (Royal Observatory, Uccle, Belgium) reported his discovery of a cometary image on mid-July exposures by Guido Pizarro with the 1.0-m ESO Schmidt telescope at the La Silla Observatory.

Further ESO Schmidt plates were then obtained, and on August 19, with the help of orbital computations by Brian Marsden (IAU Central Bureau for Astronomical Telegrams, Cambridge, Mass., USA), Elst was able to identify the object on them.

Even though the orbit (Period = 5.6 years; inclination = 1.4 deg; eccentricity = 0.17) is entirely characteristic of that of a main-belt minor planet with the implied long-term orbital stability, the continued presence of a tail seemingly confirms the object as a 'comet'.

The object now carries the designation 'Comet P/1996 N2 (Elst-Pizarro)'.

Guido Pizarro and his brother Oscar have worked as nights assistants at the ESO Schmidt telescope since 1973. It is the first comet which carries their name.

Zdenek Sekanina (Jet Propulsion Laboratory, Pasadena, California, USA) believes that the comet's narrow, straight and structureless tail is likely to be a signature of a past dust-emission episode, probably in late May - early July 1996.

At this moment, it is not known, whether it was caused by an outburst from the surface of the object (dust being pushed into space by the gas pressure of evaporating ice), or perhaps a collision with another orbiting object.

It is therefore not entirely excluded that the object is in fact a minor planet (a kilometre-size piece of solid rock), and not a comet with a comparatively large content of icy materials. Further observations are needed to decide this question.

Eso9637a is also available in a larger version. It is reproduced from a 10-min R-filter exposure obtained on Augus t 23, 1996 with the 1.5-m Danish telescope at La Silla and the DFOSC multi-mode instrument. The observers were visiting astronomers Heike Rauer (Paris Observatory, Meudon France) and Hermann Boehnhardt (Munich Observatory, Germany).

The field of view here shown is 8.1 x 6.6 arcmin with North up and East to the left. At the time of the observation, the comet was 1.68 AU from Earth and 2.68 AU from the Sun.

The comet can easily be identified in the frame. No coma is seen, only the pronounced, extremely narrow dust tail which points towards position angle p.a. = 252 deg (about 2 deg away from the direction towards the Sun).

The overall length of the tail in the frame is about 7.6 arcmin (= 555,000 km at the comet), but actually it is longer than 8.5 arcmin, since it extends beyond the edge of the field of view of the original image.

ESA DLR Scientists assess likelihood of Earth-impacting comets

According to geological and observational records, the chance of a Near Earth Object (NEO) hitting our planet is entirely possible.

Now, a new international project called NEOShield will assess the likelihood of Earth’s collision with a deadly asteroid or comet and decide what to do about it should the event occur.

Led by the German space agency’s (DLR) Institute of Planetary Research, the project began last week and will involve researchers from across Europe, Russia and the US.

According to Jonathan Amos of the BBC, an object around the size of a car enters the Earth’s atmosphere about once a year. An object the size of a football field enters the Earth’s atmosphere about every 2,000 years and every few million years, a rock enters the Earth’s atmosphere that could cause truly catastrophic damage.

While over 90 percent of these rocks have been identified and do not appear to be coming near the Earth, scientists will focus their efforts on investigating the other 10 percent and researching methods to deflect or lessen the effects of such an impact.

At the end of the three and a half year study, NEOShield scientists are hoping to propose their findings to politicians and launch a mission to demonstrate the appropriate technology, saving us from any scenarios reminiscent of Armageddon or Deep Impact.

Image: ESA

Spectacular Christmas Comet Amazes ESO Skywatchers

This photo comes from a time-lapse sequence taken by Gabriel Brammer from ESO just two days ago on 22 December 2011. 

Gabriel was finishing his night shift as support astronomer at the Paranal Observatory when the comet rose over the horizon just before dawn.

CREDIT: G. Brammer/ESO

A stunning comet that survived a recent brush with the sun is amazing astronomers again, this time in dazzling new photos captured just before sunrise over Chile.

The comet Lovejoy may not be the famed Star of Bethlehem, but it still provided a jaw-dropping sight for astronomer Gabriel Brammer, photographed the comet rising ahead of the sun on Dec. 22 at Paranal Observatory in Chile's high Atacama Desert.

Brammer is a support astronomer for the European Southern Observatory (ESO), which runs the Paranal facility. His time-lapse photos of comet Lovejoy show it rising ahead of the sun as the Paranal astronomers fire a laser beam, which serves as a guide star, into the sky. Our Milky Way galaxy and the moon are also visible in the images.

"On the last morning of my shift I tried to try catching it on camera before sunrise," Brammer said in a statement.

"The tail of the comet was easily visible with the naked eye, and the combination of the crescent moon, comet, Milky Way and the laser guide star was nearly as impressive to the naked eye as it appears in the long-exposure photos."

ESA Proba-2 tracks Comet Lovejoy through Sun’s fiery corona

ESA’s Proba-2 micro-satellite joined a flotilla of spacecraft observing deep-frozen Comet Lovejoy’s plunge through the million degree corona enshrouding the Sun, providing a close-up extreme ultraviolet view of the comet passing just 120 000 km from the Sun’s surface – and then, surprisingly, surviving.

Lovejoy had not been predicted to endure its swing by the Sun, but is now headed back out to the colder outer reaches of the Solar System, and should be visible from Earth’s northern hemisphere in mid-January.

Proba-2’s SWAP imager took part in a coordinated effort to track Comet Lovejoy as it came closest to the Sun on 16 December, working along with the ESA/NASA SOHO solar watchdog, Japan’s Hinode mission, NASA’s twin STEREO spacecraft and its Solar Dynamics Observatory.

SWAP showed the comet as a bright streak in the solar corona, with interactions between the comet tail causing brief coronal brightening and wiggles in the comet’s tale.

This was only the second time ever that a comet has been observed through an extreme-ultraviolet (EUV) solar telescope. The instrument’s observations – interrupted briefly as Proba-2 crossed behind Earth – show the comet going behind the Sun and then emerging back into view from the other side.

Comets are drawn to the gravitational pull of the Sun like moths to a flame – SOHO has identified thousands of Sun-grazing comets over the last 16 years. But up until now, what happens when a comet draws closest to the Sun has been a mystery.

Comets in the Sun’s neighbourhood usually seen with ‘coronagraph’ telescopes that block out the bright solar disc to observe the faint solar corona they are tuned for. This makes detailed images of comets nearing the Sun very hard to obtain.

It turns out however that EUV imagers that detect the extreme ultraviolet corona from the solar disk can also show the comet. Since the dust and other material making up a comet’s tail do not radiate at EUV wavelengths, this came as a surprise.