Collision Course? A Comet Heads for Mars

March 27, 2013: Over the years, the spacefaring nations of Earth have sent dozens of probes and rovers to explore Mars.  Today there are three active satellites circling the red planet while two rovers, Opportunity and Curiosity, wheel across the red sands below.  Mars is dry, barren, and apparently lifeless.

Soon, those assets could find themselves exploring a very different kind of world.

"There is a small but non-negligible chance that Comet 2013 A1 will strike Mars next year in October of 2014," says Don Yeomans of NASA's Near-Earth Object Program at JPL.  "Current solutions put the odds of impact at 1 in 2000."

In a new ScienceCast video, experts discuss what might happen if Comet 2013 A1 hits Mars. Play it

 

The nucleus of the comet is probably 1 to 3 km in diameter, and it is coming in fast, around 56 km/s (125,000 mph). "It if does hit Mars, it would deliver as much energy as 35 million megatons of TNT," estimates Yeomans.

For comparison, the asteroid strike that ended the dinosaurs on Earth 65 million years ago was about three times as powerful, 100 million megatons. Another point of comparison is the meteor that exploded over Chelyabinsk, Russia, in February of 2013, damaging buildings and knocking people down. The Mars comet is packing 80 million times more energy than that relatively puny asteroid.

An impact wouldn't necessarily mean the end of NASA's Mars program. But it would transform the program-- along with Mars itself.
"I think of it as a giant climate experiment," says Michael Meyer, lead scientist for the Mars Exploration Program at NASA headquarters.  "An impact would loft a lot of stuff into the Martian atmosphere--dust, sand, water and other debris. The result could be a warmer, wetter Mars than we're accustomed to today."
Meyer worries that solar-powered Opportunity might have a hard time surviving if the atmosphere became opaque.  Nuclear-powered Curiosity, though, would carry on just fine.  He also notes that Mars orbiters might have trouble seeing the surface, for a while at least, until the debris begins to clear.

A direct impact remains unlikely.  Paul Chodas of NASA's Near-Earth Object Program stresses that a 1 in 2000 chance of impact means there's a 1999 in 2000 chance of no impact.  "A near-miss is far more likely," he points out.

Even a near miss is a potentially big event.  The latest orbit solutions put the comet somewhere within 300,000 km of the red planet at closest approach.  That means Mars could find itself inside the comet's gassy, dusty atmosphere or "coma."  Visually, the comet would reach 0th magnitude, that is, a few times brighter than a 1st magnitude star, as seen from the Red Planet.

"Cameras on ALL of NASA's spacecraft currently operating at Mars should be able to take photographs of Comet 2013 A1," says Jim Bell, a planetary scientist and Mars imaging specialist at Arizona State University. "The issue with Mars Odyssey and the Mars Reconnaissance Orbiter will be the ability to point them in the right direction; they are used to looking down, not up. Mission designers will have to figure out if that is possible."

Opportunity might have trouble observing the aftermath of a comet impact if dust in the air cuts sunlight to the rover's solar panels. More

"The issue with the Opportunity and Curiosity rovers will be power for imaging at night," he continues. "Opportunity is solar powered and so would need to dip into reserve battery power to operate the cameras at night. Whether or not we will be able to do this will depend on how much power the rover is getting from dusty solar panels in the daytime. On the other hand, Curiosity is nuclear powered, so it could have better odds at night-time imaging."

Researchers will be keenly interested to see how the comet's atmosphere interacts with the atmosphere of Mars.  For one thing, there could be a meteor shower. "Analyzing the spectrum of disintegrating meteors could tell us something interesting about the chemistry of the upper atmosphere," notes Meyer.

Another possibility is Martian auroras.  Unlike Earth, which has a global magnetic field that wraps around our entire planet, Mars is only magnetized in patches.  Here and there, magnetic umbrellas sprout out of the ground, creating a crazy-quilt of magnetic poles concentrated mainly in the southern hemisphere.  Ionized gases hitting the top of the Martian atmosphere could spark auroras in the canopies of the magnetic umbrellas.

Even before the comet flyby was known, NASA had already decided to send a spacecraft to Mars to study the dynamics of the Martian atmosphere.  If the probe, named MAVEN (short for "Mars Atmosphere and Volatile Evolution"), is launched on time in November 2013, it would reach Mars just a few weeks before the comet in 2014.

However, notes MAVEN's principal investigator Bruce Jakosky of the University of Colorado, the spacecraft won't be ready to observe the comet when it reaches Mars.  "It takes a while to get into our science mapping orbit, deploy the booms, turn on and test the science instruments--and so on," he explains.

"MAVEN won't be fully operational until perhaps two weeks after the comet passes.  There are some effects that I would expect to linger for a relatively long period--especially if the comet hits Mars--and we will be able to observe those changes."

Astronomers around the world are monitoring 2013 A1.  Every day, new data arrive to refine the comet's orbit.  As the error bars shrink, Yeomans expects a direct hit to be ruled out.  "The odds favor a flyby, not a collision," he says.

Either way, this is going to be good. Stay tuned for updates as the comet approaches.

Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit: Science@NASA

NASA on asteroid defense: If it’s coming in three weeks, pray

Many captured video or photographs of the asteroid that exploded over Russia February 15, 2013.

The U.S. House Science, Space, and Technology Committee met in a hearing on March 19, 2013 to discuss threats from space.

On February 15, a small asteroid exploded over Chelyabinsk, Russia, generating shock waves that shattered windows and injured some 1,500 people. On that same day, asteroid 2012 DA14 made a close pass by Earth, at a scant 17,200 miles (27,700 km) from our world’s surface, closer than some communication satellites. In response to these events, the U.S. House Science, Space, and Technology Committee met in a hearing on March 19, 2013. The hearing was titled Threats from Space: A Review of U.S. Government Efforts to Track and Mitigate Asteroids and Meteors. Scientists and lawmakers discussed the risk of, and defense strategy for, an unforeseen asteroid or meteor on collision course with Earth. While trying to emphasize the need for adequate funding for detecting and characterizing near-Earth objects, and diverting them if necessary, NASA Administrator Charles Bolden said:

From the information we have, we don’t know of an asteroid that will threaten the population of the United States. But if it’s coming in three weeks…pray.

In other words, unless we know in advance that an asteroid is coming – and therefore have time to divert it – there is little we could do about an asteroid on a collision course with Earth. Bolden added:

The reason I can’t do anything in the next three weeks is because for decades we have put it off.

What exploded over Russia? Watch two videos with new answers
View from space: Russian meteor entering Earth’s atmosphere

All asteroids within a third of Earth’s distance from the sun in mid-February, 2013 are shown, with Earth at the center, in pseudo 3D. The red oval around Earth represents a distance 10 times greater than the moon’s distance. View larger.. 

Computer-generated image via Scott Manley at Armagh Observatory

NASA is currently tracking about 95 percent of Near Earth Objects (NEOs) that are .62 miles (nearly 1,000 meters) or larger in diameter. White House Science Advisor John Holdren told legislators that:

… an asteroid of that size, a kilometer or bigger, could plausibly end civilization.

So far, none of the objects NASA is tracking appear to be an immediate threat. However, as Chairman Smith pointed out:

The meteor that struck Russia was estimated to be 17 meters and wasn’t tracked at all. The smaller they are, the harder they are to spot, and yet they can be life-threatening. Some space challenges require innovation, commitment and diligence. This is one of them.

A small asteroid – like the one that exploded over Russia on February 15 – would not be world destroying. But clearly objects smaller than .62 miles (1,000 meters) have the potential to cause damage.
Representative Eddie Bernice Johnson (D-TX) said the events on February 15:

… serve as evidence that we live in an active solar system with potentially hazardous objects passing through our neighborhood with surprising frequency.

Artist’s concept of asteroid 2012-DA14, via NASA



John Holdren said the best way to detect objects that might be on a collision course with Earth would be to put an infrared-sensing telescope in a Venus-like orbit. Holdren estimated the cost of such a telescope to be between $500 million and $750 million. Another costly and time-intensive undertaking would be mounting a mission to divert a threatening object after detection. NASA’s hunt for threatening asteroids will be affected by federal sequestration cuts, and at present funding levels NASA estimates it will take nearly 20 years to identify all potentially threatening Near Earth Objects.

One solution that all lawmakers seemed amenable to was crowdsourcing, that is, working with other countries and amateur astronomers to crowdsource the hunt for threatening asteroids. Holdren said:

The odds of a Near-Earth Object strike causing massive casualties and destruction of infrastructure are very small, but the potential consequences of such an event are so large it makes sense to take the risk seriously.

Bottom line: On March 19, 2013, the House Science, Space, and Technology Committee met in a hearing titled Threats from Space: A Review of U.S. Government Efforts to Track and Mitigate Asteroids and Meteors.  Legislators, NASA administrators and others discussed the need for adequate funding for detecting and characterizing near-Earth objects, and diverting them if necessary.

Sunset Comet

March 15, 2013: For a comet, visiting the sun is risky business. Fierce solar heat vaporizes gases long frozen in the fragile nucleus, breaking up some comets and completely destroying others.

That's why astronomers weren't sure what would happen in early March when Comet Pan-STARRS, a first-time visitor to the inner solar system, dipped inside the orbit of Mercury. On March 10^th, NASA’s STEREO-B spacecraft watched as the comet made its closest approach to the sun only 28 million miles away. At that distance, the sun loomed 3 times wider and felt more than 10 times hotter than it does on Earth.

The comet survived.

A new ScienceCast video tracks the progress of Comet Pan-STARRS and the development of its wild tail. Play it

Still intact, Comet Pan-STARRS is emerging from the Sun’s glare into the sunset skies of the northern hemisphere. Solar heating has caused the comet to glow brighter than a first magnitude star. Bright twilight sharply reduces visibility, but it is still an easy target for binoculars and small telescopes 1 and 2 hours after sunset. As of March 15th, people are beginning to report that they can see the comet with the unaided eye.

Discovered in June 2011 by astronomers using the Pan-STARRS survey telescope atop the Haleakala volcano in Hawaii, the comet is paying its first visit to the inner solar system. It hails from the Oort cloud, a deep space reservoir of comets far beyond the orbit of Pluto. Because Comet PanSTARRs is a newcomer, its potential brightness and ability to withstand solar heating was unknown.
Now we know. "It is a gorgeous comet--one of the brightest in years," says astronomer Matthew Knight of the Lowell Observatory.

Comet specialist Emmanuel Jehin of the European Southern Observatory has been monitoring Pan-STARRS using a remote-controlled telescope in Chile. Based on his data, Knight concludes that "Comet Pan-STARRS seems to be producing quite a bit of dust compared to an average comet. This is very good for its visibility, because the extra dust is reflecting sunlight and making Pan-STARRS appear brighter than it would otherwise."

The amount of dust and gas spewing from the comet implies a nucleus on the order of 1 km in diameter--in other words, neither unusually large nor small. Size-wise, it is a fairly typical comet.

NASA's STEREO-B spacecraft photographed "wild striations" in the tail of Comet Pan-STARRS as it passed by the sun. Play the movie

The comet’s tail is anything but typical. STEREO-B images processed by Karl Battams of the Naval Research Lab in Washington DC reveal many wild and ragged striations in the cloud of dust trailing behind Pan-STARRS.  "Wow!" says Battams. "The fine-structure is breathtaking. We think this is caused by some fairly complex interaction between the solar wind and the comet's rotating nucleus. It's going to take computer models to figure this one out."

The comet is now receding from Earth. It will slowly dim as it heads back into deep space. Ironically, though, its visibility will improve for a while as it heads into darker skies away from the sun. In the last weeks of March it could become an easy naked-eye object.

Step outside after sunset, face west, and take a look.

 Production editor: Dr. Tony Phillips | Credit: Science@NASA

Panorama From NASA Mars Rover Shows Mount Sharp

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-097&cid=release_2013-097

PASADENA, Calif. -- Rising above the present location of NASA's Mars rover Curiosity, higher than any mountain in the 48 contiguous states of the United States, Mount Sharp is featured in new imagery from the rover.

A pair of mosaics assembled from dozens of telephoto images shows Mount Sharp in dramatic detail. The component images were taken by the 100-millimeter-focal-length telephoto lens camera mounted on the right side of Curiosity's remote sensing mast, during the 45th Martian day of the rover's mission on Mars (Sept. 20, 2012).

This layered mound, also called Aeolis Mons, in the center of Gale Crater rises more than 3 miles (5 kilometers) above the crater floor location of Curiosity. Lower slopes of Mount Sharp remain a destination for the mission, though the rover will first spend many more weeks around a location called "Yellowknife Bay," where it has found evidence of a past environment favorable for microbial life.

A version of the mosaic that has been white-balanced to show the terrain as if under Earthlike lighting, which makes the sky look overly blue, is at http://photojournal.jpl.nasa.gov/catalog/PIA16768 . White-balanced versions help scientists recognize rock materials based on their terrestrial experience. The Martian sky would look like more of a butterscotch color to the human eye. A version of the mosaic with raw color, as a typical smart-phone camera would show the scene, is at http://photojournal.jpl.nasa.gov/catalog/PIA16769 .

In both versions, the sky has been filled out by extrapolating color and brightness information from the portions of the sky that were captured in images of the terrain.

NASA's Mars Science Laboratory project is using Curiosity and the rover's 10 science instruments to investigate environmental history within Gale Crater, a location where the project has found that conditions were long ago favorable for microbial life.

Malin Space Science Systems, San Diego, built and operates the Mast Camera (Mastcam) instrument. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory mission for the NASA Science Mission Directorate, Washington, and built the rover.

For more information about the mission, visit http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl .

Follow the mission on Facebook at http://www.facebook.com/marscuriosity and on Twitter at http://www.twitter.com/marscuriosity .

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Computer glitch suspends Nasa Mars rover operation

Nasa's Mars rover Curiosity is pictured in this February 3, 2013 handout self-portrait. A computer glitch, possibly caused by radiation, has put on hold the Mars rover Curiosity's first attempt to analyse powder from inside an ancient rock, officials said.
Image by: NASA / REUTERS

A computer glitch, possibly caused by radiation, has put on hold the Mars rover Curiosity's first attempt to analyse powder from inside an ancient rock, officials say.

Engineers said they hope the Nasa rover can resume limited science operations this week.

"I don't expect there to be any long-term impact," project manager Richard Cook told Reuters. But "it's probably too early to tell."

The $2.5 billion robotic geology station was in the middle of analysing its first samples drilled out from the interior of a rock when its primary computer developed a problem on Wednesday.

The craft transmitted the results of four onboard laboratory tests to ground controllers before science operations were suspended, Cook said.

The rover landed inside the Gale Crater impact basin, located near the Martian equator, on Aug. 6, 2012, for a two-year mission to see if the planet most like Earth in the solar system has or ever had the chemistry and conditions to support microbial life.

Engineers over the weekend switched the rover to its identical backup computer system.

On Monday Curiosity was beginning to emerge from the shutdown of all but essential systems following the electronic brain transplant. Meanwhile, troubleshooting on the faulty computer system is under way.

"We plan to do a couple of more checkouts on the original computer, probably on Wednesday," Cook said.

The problem is in a flash memory system and may have been the result of a radiation hit, he added.

"If I were to guess the most likely cause, that would be it," Cook said.

Engineers want to restore Curiosity's damaged computer system so that it can be returned to service as a backup. The rover had been using its A-side computer system since before landing.

The B-side system, now in operation, was last used during Curiosity's nine-month cruise from Earth to Mars.

Results of the rover's chemical analysis of the rock sample remain set for release on March 12, lead scientist John Grotzinger wrote in an email to Reuters.

Scientists chose the rock in part because it is shot through with what appear to be minerals that form in the presence of water. Water is believed to be necessary for life.

- Times Live

The Dargon spaceship high over Mount Etna - both spitting fire. (3 March 2013)

The Dragon spaceship high over Mount Etna - both spitting fire. - Cmdr Hadfield

Van Allen Probes Discover a New Radiation Belt

Feb. 28, 2013: Earth's radiation belts were one of the first discoveries of the Space Age. A new finding published in today's issue of Science shows that we still have much to learn about them. NASA's twin Van Allen Probes, launched just last August, have revealed a previously unknown third radiation belt around Earth.

"Even 55 years after their discovery, Earth's radiation belts still are capable of surprising us," said Nicky Fox, Van Allen Probes deputy project scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "We thought we knew the radiation belts, but we don't."

A video from the Goddard Space Flight Center recaps the discovery of the new radiation belt. Play it

Previous observations of the Van Allen belts dating back to the late 1950s have documented two distinct regions of trapped radiation surrounding our planet, known as the inner and outer radiation belts. Particle sensors aboard the twin Van Allen Probes quickly revealed to scientists the existence of a transient, third radiation belt. Scientists observed the third belt for four weeks before a powerful interplanetary shock wave from the sun annihilated it.

Each of the two Van Allen Probes carries an identical set of five instrument suites that allow scientists to gather data on the belts in unprecedented detail. Key data for this discovery came from the Relativistic Electron Proton Telescope (REPT) instrument, part of the probes' Energetic Particle, Composition, and Thermal Plasma Suite (ECT).

"This is the first time we have had such high-resolution instruments look at time, space and energy together in the outer belt," says Daniel Baker, lead author of the study and REPT instrument lead at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado in Boulder. "Previous observations of the outer radiation belt resolved it as a single blurry element. When we turned REPT on just two days after launch, we clearly saw the new belt and a [gap] between it and the outer belt."

Back in the 1950s when the radiation belts were discovered, they had little effect on ordinary people. Today the radiation belts are crucial to our high-tech society.  Hundreds of satellites used for everything from weather prediction to GPS to television routinely skim the belts, subjecting themselves to energetic particles that can damage solar panels and short-circuit sensitive electronics.  During geomagnetic storms when the belts are swollen by solar activity, whole fleets of satellites can be engulfed, imperiling the technological underpinnings of daily life on the planet below. The Van Allen Probes directly address these down-to-Earth problems

"The fantastic new capabilities and advances in technology in the Van  Allen Probes allow scientists to see in unprecedented detail how the radiation belts are populated with charged particles, what causes them to change, and how they affect the upper reaches of Earth's atmosphere," says John Grunsfeld, NASA's associate administrator for science in Washington DC.

For more information about the Van Allen Probes, visit  http://www.nasa.gov/vanallenprobes

Production editor: Dr. Tony Phillips | Credit: Science@NASA

What Exploded over Russia?

Feb. 26, 2013:  When the sun rose over Russia's Ural Mountains on Friday, Feb. 15th, many residents of nearby Chelyabinsk already knew that a space rock was coming. Later that day, an asteroid named 2012 DA14 would pass by Earth only 17,200 miles above Indonesia. There was no danger of a collision, NASA assured the public.

Maybe that's why, when the morning sky lit up with a second sun and a shock wave shattered windows in hundreds of buildings around Chelyabinsk, only a few people picking themselves off the ground figured it out right away. This was not a crashing plane or a rocket attack.

"It was a meteor strike--the most powerful since the Tunguska event of 1908," says Bill Cooke of NASA's Meteoroid Environment Office.

A new ScienceCast video reviews what researchers have learned about the Russian meteor. Play it

 

In a coincidence that still has NASA experts shaking their heads, a small asteroid completely unrelated to 2012 DA14 struck Earth only hours before the publicized event. The impactor flew out of the blue, literally from the direction of the sun where no telescope could see it, and took everyone by surprise.

"These are rare events and it is incredible to see them happening on the same day," says Paul Chodas of NASA's near-Earth Object Program at JPL.

Researchers have since pieced together what happened. The most telling information came from a network of infrasound sensors operated by the Comprehensive Test Ban Treaty Organization (CTBTO). Their purpose is to monitor nuclear explosions.

Listen to the infrasound recording, sped up 135x into the range of human hearing. Play it
 

Infrasound is a type of very low-frequency sound wave that only elephants and a few other animals can hear. It turns out that meteors entering Earth's atmosphere cause ripples of infrasound to spread through the air of our planet. By analyzing infrasound records, it is possible to learn how long a meteor was in the air, which direction it traveled, and how much energy it unleashed.

The Russian meteor's infrasound signal was was the strongest ever detected by the CTBTO network. The furthest station to record the sub-audible sound was 15,000km away in Antarctica.

Western Ontario Professor of Physics Peter Brown analyzed the data: "The asteroid was about 17 meters in diameter and weighed approximately 10,000 metric tons," he reports. "It struck Earth's atmosphere at 40,000 mph and broke apart about 12 to 15 miles above Earth's surface. The energy of the resulting explosion exceeded 470 kilotons of TNT." For comparison, the first atomic bombs produced only 15 to 20 kilotons.

Based on the trajectory of the fireball, analysts have also plotted its orbit. "It came from the asteroid belt, about 2.5 times farther from the sun than Earth," says Cooke.
Comparing the orbit of the Russian meteor to that of 2012 DA14, Cooke has shown that there is no connection between the two. "These are independent objects," he says. "The fact that they reached Earth on the same day, one just a little closer than the other, appears to be a complete coincidence." [orbit diagram]

Infrasound records confirm that the meteor entered the atmosphere at a shallow angle of about 20 degrees and lasted more than 30 seconds before it exploded. The loud report, which was heard and felt for hundreds of miles, marked the beginning of a scientific scavenger hunt. Thousands of fragments of the meteor are now scattered across the Ural countryside, and a small fraction have already been found.

Preliminary reports, mainly communicated through the media, suggest that the asteroid was made mostly of stone with a bit of iron--"in other words, a typical asteroid from beyond the orbit of Mars," says Cooke. "There are millions more just like it."

And that is something to think about as the cleanup in Chelyabinsk continues.

Author: Dr. Tony Phillips |Production editor: Dr. Tony Phillips | Credit: Science@NASA

NASA Rover Confirms First Drilled Mars Rock Sample

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2013-067&cid=release_2013-067

PASADENA, Calif. -- NASA's Mars rover Curiosity has relayed new images that confirm it has successfully obtained the first sample ever collected from the interior of a rock on another planet. No rover has ever drilled into a rock beyond Earth and collected a sample from its interior.

Transfer of the powdered-rock sample into an open scoop was visible for the first time in images received Wednesday at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"Seeing the powder from the drill in the scoop allows us to verify for the first time the drill collected a sample as it bore into the rock," said JPL's Scott McCloskey, drill systems engineer for Curiosity. "Many of us have been working toward this day for years. Getting final confirmation of successful drilling is incredibly gratifying. For the sampling team, this is the equivalent of the landing team going crazy after the successful touchdown."

The drill on Curiosity's robotic arm took in the powder as it bored a 2.5-inch (6.4-centimeter) hole into a target on flat Martian bedrock on Feb. 8. The rover team plans to have Curiosity sieve the sample and deliver portions of it to analytical instruments inside the rover.

The scoop now holding the precious sample is part of Curiosity's Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) device. During the next steps of processing, the powder will be enclosed inside CHIMRA and shaken once or twice over a sieve that screens out particles larger than 0.006 inch (150 microns) across.

Small portions of the sieved sample later will be delivered through inlet ports on top of the rover deck into the Chemistry and Mineralogy (CheMin) instrument and Sample Analysis at Mars (SAM) instrument.

In response to information gained during testing at JPL, the processing and delivery plan has been adjusted to reduce use of mechanical vibration. The 150-micron screen in one of the two test versions of CHIMRA became partially detached after extensive use, although it remained usable. The team has added precautions for use of Curiosity's sampling system while continuing to study the cause and ramifications of the separation.

The sample comes from a fine-grained, veiny sedimentary rock called "John Klein," named in memory of a Mars Science Laboratory deputy project manager who died in 2011. The rock was selected for the first sample drilling because it may hold evidence of wet environmental conditions long ago. The rover's laboratory analysis of the powder may provide information about those conditions.

NASA's Mars Science Laboratory Project is using the Curiosity rover with its 10 science instruments to investigate whether an area within Mars' Gale Crater ever has offered an environment favorable for microbial life. JPL, a division of the California Institute of Technology, Pasadena, manages the project for NASA's Science Mission Directorate in Washington.

An image of the drill's rock powder held in the scoop is online at: http://photojournal.jpl.nasa.gov/catalog/PIA16729 .

For more about the mission, visit: http://www.jpl.nasa.gov/msl , http://www.nasa.gov/msl .

You can follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity and http://www.twitter.com/marscuriosity .

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov

NASA loses communication with Space Station

(CNN) -- NASA lost communication with the International Space Station on Tuesday and has established only sporadic connections since, according to NASA spokesman Josh Byerly.

The space agency says it is currently only able to communicate every 90 minutes when the facility passes over ground stations in Russia.

The station, which is carrying one American astronaut and two Russian cosmonauts, does not appear to be in danger, Byerly said.

The loss in communications is not considered unprecedented, though it's considered a cause for concern, officials said.

- CNN

We Probably Wouldn't Even See A Doomsday Asteroid Until It Was Too Late

Via the European Space Agency, an artist's rendering of Apophis.

Forget blowing up a doomsday asteroid with nuclear bombs. We probably won’t even see it coming.

David Ewalt reports on asteroid 99942 Apophis, a hunk of space rock discovered back in 2004 that astronomers said had “a small chance” of collision “with the Earth in the year 2029, causing an explosion equivalent to 1480 megatons of TNT–nearly 30 times larger than the biggest hydrogen bomb ever detonated.”

We had a “close pass” with the asteroid yesterday—veering around 9 million miles close to our planet.

According to Ewalt, scientists are now claiming the asteroid is about 20% bigger than they first thought, and even though it’s still not likely that Apophis will collide with our planet, if it did the impact would be even more dire. The near pass should help scientists project collision likelihood well into the future.

Apophis is what we refer to as a Near Earth Object (or NEO.) NEOs are “small objects in the solar system (asteroids and short-period comets) with orbits that regularly bring them close to the Earth and which, therefore, are capable someday of striking our planet,” according to NASA.

What’s actually frightening about NEOs is that there are actually lots and lots of them that we don’t even know about. 99942 Apophis is an outlier not because it could theoretically hit Earth, but because we know about it in the first place. Scientists tagged it as a possible 2029 collision. That’s quite a few years to formulate some sort of defense.

So how much warning will we really have if an asteroid is about to hit Earth? The answer is pretty grim.

“With so many of even the larger NEOs remaining undiscovered, the most likely warning today would be zero,” NASA informs us. We would see nothing at all until suddenly, just as the impact occurred, we noticed a “flash of light and the shaking of the ground as it hit.” Then poof.

Compared to the sudden, unanticipated impact, “if the current surveys actually discover a NEO on a collision course, we would expect many decades of warning. Any NEO that is going to hit the Earth will swing near our planet many times before it hits, and it should be discovered by comprehensive sky searches like Spaceguard. In almost all cases, we will either have a long lead time or none at all.”

Apophis obviously falls into the “many decades” camp, though it’s unlikely it will hit Earth in our lifetime.

The more likely scenario? I’ll be typing a post like this one when suddenly “a flash of light and the shaking of the ground” and then…well you get the picture.

Not much fanfare, I’ll admit, but life is usually stranger—and more abrupt—than the movies.

Erik Kain - Forbes

Comet PANSTARRS possibly visible to eye in March 2013

It’s too early to know whether Comet ISON or Comet PANSTARRS – the two exciting comets of 2013 – will dazzle or fizzle. But these two are worth watching!

There is a lot of excitement about Comet ISON, which might become a very bright comet, visible across the globe, by the end of 2013. But, before that happens, a second comet might become visible to the eye alone around the time it is closest to the sun in March of 2013. The Pan-STARRS telescope in Hawaii discovered this comet in June 2011. Since comets carry the names of their discoverers, it has been designated C/2011 L4 (PANSTARRS). Only the largest telescopes on Earth could glimpse Comet PANSTARRS when it was first discovered, but amateurs telescopes began to pick it up by May 2012. By October 2012, its surrounding coma was seen to be large and fine at an estimated 75,000 miles (120,000 kilometers) wide. In March 2013, by some estimates, this comet should get as bright as Venus, but do remember that comets are notoriously difficult to predict. As comet-hunter David Levy once famously said:

Comets are like cats; they have tails, and they do precisely what they want.

Look below for a month-by-month Comet PANSTARRS viewing guide.

Comet C/2011 L4 (PANSTARRS) was exceedingly faint when Hawaii’s Pan-STARRS 1 telescope discovered it on June 6, 2011.

March 5, 2013. Comet PANSTARRS passes closest to Earth at 1.10 Astronomical Units, (AU). One AU equals one Earth-sun distance, about 93 million miles or 150 million kilometers. In other words, this comet will pass slightly farther from us than our distance from the sun. No worries about it hitting us.

March 10. The comet passes closest to the sun – as close as our sun’s innermost planet, Mercury – at 0.30 AU – or about 28 million miles (45 million kilometers). Comets are typically brightest and most active around the time they are closest to the sun when solar heating vaporizes ice and dust from the comet’s outer crust. Not only will the comet quickly brighten, but it should also develop the long classic comet dust tail.

Throughout March 2013. The comet should be visible in the Northern Hemisphere evening sky low in the west after sunset. It will higher each night during March 2013 as it moves from being in front of the constellation Pisces to being in front of the constellations Pegasus and Andromeda. At this time, the comet should have its bright dust tail, and be visible to the unaided eye. It should, at least, if it lives up to expectations.

April 2013. No matter how bright it gets in March, the comet will surely fade as April arrives, as it moves away from the sun and back out into the depths of space. But it will be located far to the north on the sky’s dome and will be circumpolar for northerly latitudes in the Northern Hemisphere. That means it might be visible somewhere in the northern sky throughout the night for northern observers. What’s more, the comet will be near in the sky to another beautiful and fuzzy object in our night sky, the Andromeda Galaxy (M31), the nearest large spiral galaxy to our Milky Way. If the comet truly is bright then, and if it still has a substantial tail, it’ll be an awesome photo opportunity!

Comet PANSTARRS on the evening of April 6, 2013. This view is to the east that evening. The oval near the comet is the Andromeda galaxy. You’ll want a dark sky to see both the comet and the galaxy. Chart via Dave Eagle at www.eagleseye.me.uk. Used with permission. View larger.

By the way, Comet PANSTARRS is considered a non-periodic comet. It probably took millions of years to come from the great Oort comet cloud surrounding our solar system. Once it rounds the sun, experts say, its orbit will shorten to only 110,000 years. It is, for sure, a once-in-a-lifetime comet.

Bottom line: As 2013 begins, there are two comets to get excited about. One is Comet PANSTARRS, which will be brightest in March 2013. The other is Comet ISON, which might become a daylight comet in late 2013. Although a comet’s movement in our sky can be predicted, its brightness cannot be. It’s too early to know whether Comet PANSTARRS or Comet ISON – the two exciting comets of 2013 – will dazzle or fizzle. But these two are worth watching!

- EarthSky

Quadrantid meteors in moonlight before dawn January 3

Quadrantid meteor streaking by Spica, Virgo's brightest star. Photo via Navicore.

The annual Quadrantid meteor shower is expected to produce its greatest number of meteors in the wee hours before dawn tomorrow: Thursday, January 3. Before dawn on January 4 might also be a possibility – especially for far eastern Asia. This year, 2013, the waning gibbous moon will be in the sky during the peak hours for watching meteors. But you might see some of the brighter meteors, even in moonlight.

The Quadrantid meteor shower is capable of matching the meteor rates of the better known August Perseid and December Geminid showers. It has been known to produce up to 50-100 or more meteors per hour in a dark sky. This shower favors the Northern Hemisphere. That’s because its radiant point – the point in the sky from which the meteors appear to radiate – is far to the north on the sky’s dome.

So why isn’t the Quadrantid shower as celebrated as the Perseid and Geminid showers? It’s because the Quadrantid shower has a narrow peak that lasts for only a few hours. If you miss the peak – which is easy to do – this otherwise tepid shower is sure to disappoint.

If you’re thinking of watching the Quadrantids, go right ahead. Meteor shower peaks are rarely certain, and sometimes a gamble on a shower will reward you with a good show. Just be aware you might not see a whole lot of meteors! No matter where you are in the Northern Hemisphere, the best time to watch is between midnight and dawn, local time. Unfortunately, the waning gibbous moon will rise at about the time that the shower’s radiant is coming up. Afterwards, the moon will shine for the rest of the night.

The Quadrantid shower is named after the defunct 19th century constellation Quadrans Muralis. If you trace the paths of the Quandrantids backward, they appear to radiate from a point where this constellation once reigned in the sky. If you wish, you can locate the Quadrantid radiant in reference to the Big Dipper and the bright star Arcturus. Use the chart at the top of this post.

But you don’t need to find the radiant to enjoy the Quadrantids. You need a dark, open sky, and you need to look in a general north-northeast direction for an hour or so before dawn. That’s the Quadrantid meteor shower – before dawn January 3, 2013 – for the world’s northerly latitudes. If you’re in Asia, you might try between midnight and dawn on January 4 as well. Who knows? Some of the Quadrantids meteors might be bright enough to dazzle you, even in bright moonlight.

- EarthSky

Christmas Sky Show

Dec. 21, 2012: Just when you thought Christmas was over: At the end of the day on Dec. 25th, a pair of holiday lights will pop out of the deepening twilight. Jupiter and the Moon are having a Christmas conjunction.

It’s a beautiful apparition, visible all around the globe. Even city dwellers, who often miss astronomical events because of light pollution, can see the show. Separated by less than 2 degrees, the bright pair will beam right through urban lights.

A new ScienceCast video previews the Christmas-night conjunction of the Moon and Jupiter. Play it

For anyone who gets a telescope for Christmas, the timing is perfect. Jupiter and the Moon are among the most satisfying targets for backyard optics. A quick sweep of the telescope from Jupiter to the Moon and back again will reveal Jupiter's storms and cloud belts, the Moon's mountains and impact craters, and of course the four Galilean satellites circling the giant planet like a miniature solar system.

Jupiter's Great Red Spot is spinning up. Learn more about it in the ScienceCast video Christmas Sky Show

Jupiter's trademark Great Red Spot will also be on display--and it is worth a look. Astronomers recently announced that the enormous swirling storm, twice as wide as the planet Earth, is "spinning up."

Actually, explains planetary scientist Glenn Orton of NASA's Jet Propulsion Laboratory, "the Red Spot is shrinking." He likens it to "the iconic picture of a figure skater pulling her arms in to spin faster. As the size contracts, the spin rate increases."

John Rogers, head of the British Astronomical Association's Jupiter Section, noticed the phenomenon in recent pictures of Jupiter snapped by amateur astronomers. He was able to track a dark cloudy feature as it swirled three times around the Red Spot's central vortex. The circulating streak completed the circuit in only 4.0 days, shorter than the 4.5 days Rogers measured in 2006 using the same method.

Looking back in time, "the trend of decreasing rotation period has been consistent at least since Voyager visited Jupiter in 1979," says Rogers. As the spot shrinks, it also changes shape. Decades ago the Red Spot looked like a sausage – now it’s more circular.

What happens next is hard to say. "Perhaps the Red Spot will continue to shrink and eventually disappear," speculates Rogers. "Or perhaps it will be rejuvenated if some new storm arises to reinforce it."

One thing is certain, Christmas night is a good time to look. The Red Spot will be transiting Jupiter's middle for observers across North America and will be perfectly positioned for telescopic observations.

But you don't need a telescope to enjoy the show. Step outside at sunset on Dec. 25th and look east. After all, Christmas isn't really over until you've seen the holiday lights.


Author: Dr. Tony Phillips |Production editor: Dr. Tony Phillips | Credit: Science@NASA

Magnetic pole reversal not a sign of doomsday

A schematic diagram of Earth's interior and the movement of magnetic north from 1900 to 1996. The outer core is the source of the geomagnetic field. Graphic Credit: Dixon Rohr / NASA

Scientists understand that Earth’s magnetic field has flipped its polarity many times over the millennia. In other words, if you were alive about 800,000 years ago, and facing what we call ‘north’ with a magnetic compass in your hand, the needle would point to ‘south.’

This is because a magnetic compass is calibrated based on Earth’s poles. The N-S markings of a compass would be 180 degrees wrong if the polarity of today’s magnetic field were reversed. Many doomsday theorists have tried to take this natural geological occurrence and suggest it could lead to Earth’s destruction. But would there be any dramatic effects? The answer, from the geologic and fossil records we have from hundreds of past magnetic polarity reversals, seems to be ‘no.’

Reversals are the rule, not the exception. Earth has settled in the last 20 million years into a pattern of a pole reversal about every 200,000 to 300,000 years, although it has been more than twice that long since the last reversal. A reversal happens over hundreds or thousands of years, and it is not exactly a clean back flip. Magnetic fields morph and push and pull at one another, with multiple poles emerging at odd latitudes throughout the process. Scientists estimate reversals have happened at least hundreds of times over the past three billion years. And while reversals have happened more frequently in “recent” years, when dinosaurs walked Earth a reversal was more likely to happen only about every one million years.

Image Credit: Peter Reid /NASA

Earth’s polarity is not a constant. Unlike a classic bar magnet, or the decorative magnets on your refrigerator, the matter governing Earth’s magnetic field moves around. Geophysicists are pretty sure that the reason Earth has a magnetic field is because its solid iron core is surrounded by a fluid ocean of hot, liquid metal. This process can also be modeled with supercomputers.

Ours is, without hyperbole, a dynamic planet. The flow of liquid iron in Earth’s core creates electric currents, which in turn create the magnetic field. So while parts of Earth’s outer core are too deep for scientists to measure directly, we can infer movement in the core by observing changes in the magnetic field. The magnetic north pole has been creeping northward – by more than 600 miles (1,100 km) – since the early 19th century, when explorers first located it precisely. It is moving faster now, actually, as scientists estimate the pole is migrating northward about 40 miles per year, as opposed to about 10 miles per year in the early 20th century.

The science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia. While the conditions that cause polarity reversals are not entirely predictable – the north pole’s movement could subtly change direction, for instance – there is nothing in the millions of years of geologic record to suggest that any of the 2012 doomsday scenarios connected to a pole reversal should be taken seriously. A reversal might, however, be good business for magnetic compass manufacturers.

- EarthSky

Ebb and Flow crash into moon

Washington - Two Nasa probes crashed into the moon on Monday after spending months gathering data by orbiting miles above the lunar surface, the US space agency said.

The site where the tiny probes, dubbed Ebb and Flow, crashed will be named after astronaut Sally Ride, the first American woman in space.

Ride, who died earlier this year, had led the GRAIL mission's MoonKam project for students from around the world to choose targets for the probes' cameras.

"Sally was all about getting the job done, whether it be in exploring space, inspiring the next generation, or helping make the GRAIL mission the resounding success it is today," GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge said in a statement.

"As we complete our lunar mission, we are proud we can honour Sally Ride's contributions by naming this corner of the moon after her."

Ebb and Flow slammed into the lunar surface as planned at 22:28 GMT and 22:29 GMT at a whopping 1.7km/second. The Sally K Ride Impact Site is on the southern surface of a mountain near a crater named Goldschmidt.

There was no image of the crash because the area was in the dark at the time, Nasa said.

The probes were destroyed after running low on fuel and sinking too low in orbit to conduct any more missions, the space agency said.

During their work life the probes took more than 115 000 images of the lunar surface, generating the highest resolution gravity map ever gathered from a celestial body.

The map will help provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved, according to scientists.

"We will miss our lunar twins, but the scientists tell me it will take years to analyse all the great data they got, and that is why we came to the moon in the first place," said GRAIL project manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena, California.

"So long, Ebb and Flow, and we thank you."

Launched in September 2011, Ebb and Flow had been orbiting the moon since 1 January. At some points, they were flying just a few kilometres above the moon's tallest mountains.

Ebb and Flow fired their main engines until the tanks were empty, allowing Nasa to determine precisely how much fuel is left and help improve predictions of fuel needs for future missions.

The $500m GRAIL mission was the 110th moon exploration mission.

Those missions include the six manned Apollo flights from 1969 to 1972 that saw 12 Americans land on the lunar surface.

- AFP/News24

Will our solar system cross the galactic plane on December 21, 2012?

Will our solar system cross the plane of our Milky Way galaxy in 2012? No. The solar system will not cross the galactic plane on December 21, 2012 – or on any other date in 2012 – or anytime soon. Sure, our Milky Way galaxy is flat and round, like a pancake. And yes, the sun does weave in and out of the galaxy’s flat plane. However, astronomers have determined that we’re currently moving away from, not toward the galactic plane. By astronomers’ estimates, our solar system last crossed the plane of the Milky Way galaxy some 3 million years ago. We won’t do so again for another 30 million years.

See the video below to visualize where we reside relative to the galactic plane.

This video is from Morehead Planetarium / Science360 in Chapel Hill, North Carolina. It’s one of a series of excellent videos by Morehead attempting to answer the many wild, crazy, improbable and false doomsday scenarios related to December 2012. Thank goodness this month is finally here. Soon it’ll be January. See you in 2013!

Bottom line Morehead Planetarium / Science360 produced a good video discussing the fact that our solar system will not cross through the plane of our Milky Way galaxy on December 21, 2012. In fact, we won’t pass through the galactic plane again for 30 million years.

- Earth Sky

Will the solar system planets align on December 21, 2012?

No, the planets of the solar system will not align at the solstice on December 21, 2012.

The diagram below shows the positions of all the solar system planets (and the dwarf planet Pluto) at the instant of the December 2012 solstice (2012 December 21 at 11:12 UTC).

Positions of the planets on December 21, 2012

The positions of the solar system planets on the December 21 solstice (2012 December 21 at 11:12 Universal Time) Image credit: Solar System Live.

Look for yourself. Do these scattered planets look aligned to you? If you squint, I suppose you could say the planets Jupiter, Earth and Venus appear aligned in space. However, such an “alignment” is not rare. If you could somehow reside above the solar system, and continually watch the planets move in space over years or millenia, you’d find that the planets make all sorts of patterns with respect to each other, endlessly, as they orbit the sun. How could it be otherwise?

Should you ever want to know the positions of the planets at the drop of the hat, click here or here.
By the way, the above diagram shows the planetary positions from the direction north of the ecliptic – Earth’s orbital plane. As seen from the north of the ecliptic, the planets go counter-clockwise around the sun. The planets circle the sun on nearly – but not exactly – the same plane that Earth does. The portion of the planetary orbit highlighted in blue lies north of (above) the ecliptic – Earth’s orbital plane – while that highlighted in green resides south of the ecliptic.

Perhaps you’ve seen images such as the one below. We used this image ourselves on our December 1 night sky post, in which we spoke of all the solar system planets being visible in December.

Relative sizes of planets and dwarf planets of the solar system. Image credit: Wikimedia Commons.

This portrayal of the solar system gives the relative sizes of the sun and planets, and the order of the planets (and dwarf planets) going outward from the sun. But this illustration is not dated December 21, 2012. It has no date at all. It does not show the relative distances of the planets, or their positions relative to the plane of the solar system, or their locations in orbit on December 21, 2012 or any other day. In short, this illustration does not show the planets lining up on December 21, 2012.

The so-called planetary alignment associated with December 2012 solstice is only one of numerous fraudulent claims made by pseudoscientific doomsday prognosticators. Our advice is to celebrate the solstice as our ancestors have done since time immemorial and to enjoy New Year’s celebrations! We’ll see you in 2013.

Bottom line: The planets of our solar system will not align on December 21, 2012. This post contains a diagram showing the positions of the planets on that day.

- Earth Sky

From Cassini for the Holidays: A Splendor Seldom Seen

The full version of this story with accompanying images is at:

http://www.jpl.nasa.gov/news/news.php?release=2012-402&cid=release_2012-402

PASADENA, Calif -- Just in time for the holidays, NASA's Cassini spacecraft, in orbit around Saturn for more than eight years now, has delivered another glorious, backlit view of the planet Saturn and its rings.

On Oct. 17, 2012, during its 174th orbit around the gas giant, Cassini was deliberately positioned within Saturn's shadow, a perfect location from which to look in the direction of the sun and take a backlit view of the rings and the dark side of the planet. Looking back towards the sun is a geometry referred to by planetary scientists as "high solar phase;" near the center of your target's shadow is the highest phase possible. This is a very scientifically advantageous and coveted viewing position, as it can reveal details about both the rings and atmosphere that cannot be seen in lower solar phase.

The last time Cassini had such an unusual perspective on Saturn and its rings, at sufficient distance and with sufficient time to make a full system mosaic, occurred in September 2006, when it captured a mosaic, processed to look like natural color, entitled "In Saturn's Shadow" (http://photojournal.jpl.nasa.gov/catalog/?IDNumber=PIA08329 ). In that mosaic, planet Earth put in a special appearance, making "In Saturn's Shadow" one of the most popular Cassini images to date.

The mosaic being released today by the mission and the imaging team, in celebration of the 2012 holiday season, does not contain Earth; along with the sun, our planet is hidden behind Saturn. However, it was taken when Cassini was closer to Saturn and therefore shows more detail in the rings than the one taken in 2006.

The new processed mosaic, composed of 60 images taken in the violet, visible and near infrared part of the spectrum, can be found at http://www.nasa.gov/cassini , http://saturn.jpl.nasa.gov and http://ciclops.org .

"Of all the many glorious images we have received from Saturn, none are more strikingly unusual than those taken from Saturn's shadow," said Carolyn Porco, Cassini's imaging team lead based at the Space Science Institute in Boulder, Colo.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the U.S., England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov

Steve Mullins 720-974-5859

Space Science Institute, Boulder, Colo.

media@ciclops.org

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NASA's GRAIL Lunar Impact Site Named for Astronaut Sally Ride

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.php?release=2012-401&cid=release_2012-401

PASADENA, Calif. -- NASA has named the site where twin agency spacecraft impacted the moon Monday in honor of the late astronaut Sally K. Ride, who was America's first woman in space and a member of the probes' mission team.

Last Friday, Ebb and Flow, the two spacecraft comprising NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, were commanded to descend into a lower orbit that would result in an impact Monday on a mountain near the moon's north pole. The formation-flying duo hit the lunar surface as planned at 2:28:51 p.m. PST (5:28:51 p.m. EST) and 2:29:21 p.m. PST (5:29:21 p.m. EST) at a speed of 3,760 mph (1.7 kilometers per second). The location of the Sally K. Ride Impact Site is on the southern face of an approximately 1.5-mile-tall (2.5-kilometer) mountain near a crater named Goldschmidt.

"Sally was all about getting the job done, whether it be in exploring space, inspiring the next generation, or helping make the GRAIL mission the resounding success it is today," said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. "As we complete our lunar mission, we are proud we can honor Sally Ride's contributions by naming this corner of the moon after her."

The impact marked a successful end to the GRAIL mission, which was NASA's first planetary mission to carry cameras fully dedicated to education and public outreach. Ride, who died in July after a 17-month battle with pancreatic cancer, led GRAIL's MoonKAM (Moon Knowledge Acquired by Middle School Students) Program through her company, Sally Ride Science, in San Diego.

Along with its primary science instrument, each spacecraft carried a MoonKAM camera that took more than 115,000 total images of the lunar surface. Imaging targets were proposed by middle school students from across the country and the resulting images returned for them to study. The names of the spacecraft were selected by Ride and the mission team from student submissions in a nationwide contest.

"Sally Ride worked tirelessly throughout her life to remind all of us, especially girls, to keep questioning and learning," said Sen. Barbara Mikulski of Maryland. "Today her passion for making students part of NASA's science is honored by naming the impact site for her."

Fifty minutes prior to impact, the spacecraft fired their engines until the propellant was depleted. The maneuver was designed to determine precisely the amount of fuel remaining in the tanks. This will help NASA engineers validate computer models to improve predictions of fuel needs for future missions.

"Ebb fired its engines for 4 minutes 3 seconds, and Flow fired its for 5 minutes 7 seconds," said GRAIL project manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It was one final important set of data from a mission that was filled with great science and engineering data."

The mission team deduced that much of the material aboard each spacecraft was broken up in the energy released during the impacts. Most of what remained probably is buried in shallow craters. The craters' size may be determined when NASA's Lunar Reconnaissance Orbiter returns images of the area in several weeks.

Launched in September 2011, Ebb and Flow had been orbiting the moon since Jan. 1, 2012. The probes intentionally were sent into the lunar surface because they did not have sufficient altitude or fuel to continue science operations. Their successful prime and extended science missions generated the highest-resolution gravity field map of any celestial body. The map will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

"We will miss our lunar twins, but the scientists tell me it will take years to analyze all the great data they got, and that is why we came to the moon in the first place," Lehman said. "So long, Ebb and Flow, and we thank you." JPL manages the GRAIL mission for NASA's Science Mission Directorate in Washington. GRAIL is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft.

Join the conversation on Twitter by following the hashtag #GRAIL. To learn more about all the ways to connect and collaborate with NASA, visit: http://www.nasa.gov/connect .

For the mission's press kit and other information about GRAIL, visit: http://www.nasa.gov/grail . You can follow JPL News on Facebook at: http://www.facebook.com/nasajpl and on Twitter at: http://www.twitter.com/nasajpl .

D.C. Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

Dwayne Brown 202-358-1726
Headquarters, Washington
dwayne.c.brown@nasa.gov

Sarah McDonnell 617-253-8923
Massachusetts Institute of Technology, Cambridge, Mass.
s_mcd@mit.edu

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