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Comet ISON

Posted on 2013/12/03 by admin

NASA — Did comet Ison survive its trip around the sun? After several days of continued observations, scientists continue to work to determine and to understand the fate of Comet ISON: There’s no doubt that the comet shrank in size considerably as it rounded the sun and there’s no doubt that something made it out on the other side to shoot back into space. The question remains as to whether the bright spot seen moving away from the sun was simply debris, or whether a small nucleus of the original ball of ice was still there. Regardless, it is likely that it is now only dust.

Comet ISON, which began its journey from the Oort Cloud some 3 million years ago, made its closest approach to the sun on Nov. 28, 2013. The comet was visible in instruments on NASA’s Solar Terrestrial Relations Observatory, or STEREO, and the joint European Space Agency/NASA Solar and Heliospheric Observatory, or SOHO, via images called coronagraphs. Coronagraphs block out the sun and a considerable distance around it, in order to better observe the dim structures in the sun’s atmosphere, the corona. As such, there was a period of several hours when the comet was obscured in these images, blocked from view along with the sun. During this period of time, NASA’s Solar Dynamics Observatory could not see the comet, leading many scientists to surmise that the comet had disintegrated completely. However, something did reappear in SOHO and STEREO coronagraphs some time later – though it was significantly less bright.

Whether that spot of light was merely a cloud of dust that once was a comet, or if it still had a nucleus – a small ball of its original, icy material – intact, is still unclear. It seems likely that as of Dec. 1, there was no nucleus left. By monitoring its changes in brightness over time, scientists can estimate whether there’s a nucleus or not, but our best chance at knowing for sure will be if the Hubble Space Telescope makes observations later in December 2013.

Regardless of its fate, Comet ISON did not disappoint researchers. Over the last year, observatories around the world and in space gathered one of the largest sets of comet observations of all time, which should provide fodder for study for years to come. The number of space-based, ground-based, and amateur observations were unprecedented, with twelve NASA space-based assets observing over the past year.

VIDEO
Comet ISON is shown approaching the sun and curving away from it in this movie containing imagery from both NASA’s Solar Terrestrial Relations Observatory and the joint ESA/NASA Solar and Heliospheric Observatory from November 2013. ISON dims dramatically as it streams away from the sun.

Galaxy Growth Like Watching Paint Dry

Posted on 2013/11/01 by admin

NASA — Watching a tree grow might be more frustrating than waiting for a pot to boil, but luckily for biologists, there are tree rings. Beginning at a tree trunk’s dense core and moving out to the soft bark, the passage of time is marked by concentric rings, revealing chapters of the tree’s history.

Galaxies outlive trees by billions of years, making their growth impossible to see. But like biologists, astronomers can read the rings in a galaxy’s disk to unravel its past. Using data from NASA’s Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX), scientists have acquired more evidence for the “inside-out” theory of galaxy growth, showing that bursts of star formation in central regions were followed one to two billion years later by star birth in the outer fringes.

“Initially, a rapid star-forming period formed the mass at the center of these galaxies, followed later by a star-forming phase in the outer regions. Eventually, the galaxies stop making stars and become quiescent,” said Sara Petty of Virginia Tech, Blacksburg, Va., lead author of a paper appearing in the October 2013 issue of the Astronomical Journal. “This later star-forming phase could have been caused by minor mergers with gas-rich neighbors, which provide the fuel for new stars.”

The discovery may also solve a mystery of elderly galaxies. The galaxies in the study, known as “red and dead” for their red color and lack of new star births, have a surprising amount of ultraviolet light emanating from the outer regions. Often, ultraviolet light is generated by hot, young stars, but these galaxies were considered too old to host such a young population.

The solution to the puzzle is likely hot, old stars. Petty and colleagues used a new multi-wavelength approach to show that the unexplained ultraviolet light appears to be coming from a late phase in the lives of older stars, when they blow off their outer layers and heat up.

GALEX and WISE turned out to be the ideal duo for the study. GALEX was sensitive to the ultraviolet light, whereas WISE sees the infrared light coming from older stars. GALEX is no longer operating, but WISE was recently reactivated to hunt asteroids, a project called NEOWISE (see http://www.jpl.nasa.gov/news/news.php?release=2013-257 ). Both telescopes have large fields of view, allowing them to easily capture images of entire galaxies.

“The synergy between GALEX and WISE produces a very sensitive measurement of where the hot, older stars reside in these red-and-dead galaxies,” said Don Neill, co-author of the paper from the California Institute of Technology, Pasadena. “This allows us to map the progress of star formation within each galaxy.”

Ned Wright of UCLA, a co-author of the study and the principal investigator of WISE before it was reactivated, compares the multi-wavelength range of the two telescopes to musical notes, “WISE itself covers the equivalent of a three-octave range, while WISE and GALEX together cover a seven-octave range.”

The technical paper for this study is online at http://arxiv.org/abs/1307.6282 .

NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages and operates the recently activated NEOWISE mission for NASA’s Science Mission Directorate. The WISE mission was selected competitively under NASA’s Explorers Program managed by the agency’s Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. More information is online at http://www.nasa.gov/wise and http://wise.astro.ucla.edu and http://jpl.nasa.gov/wise .

Caltech led the Galaxy Evolution Explorer mission and was responsible for science operations and data analysis. JPL managed the mission and built the science instrument. The mission was developed under NASA’s Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d’Etudes Spatiales (CNES) in France collaborated on this mission. Graphics and additional information about the Galaxy Evolution Explorer are online at http://www.nasa.gov/galex and http://www.galex.caltech.edu.

Russian Meteor Plume

Posted on 2013/08/22 by admin

Atmospheric physicist Nick Gorkavyi missed witnessing an event of the century last winter when a meteor exploded over his hometown of Chelyabinsk, Russia. From Greenbelt, Md., however, NASA’s Gorkavyi and colleagues witnessed the atmospheric aftermath. The explosion created a never-before-seen belt of “meteor dust” that circulated through the stratosphere for at least three months.

Shortly after dawn on Feb. 15, 2013, the meteor, or bolide, measuring 18 meters across and weighing 11,000 metric tons, screamed into Earth’s atmosphere at 18.6 km/s (41,600 mph). Burning from the friction with Earth’s thin air, the space rock exploded 23 km above Chelyabinsk, releasing more than 30 times the energy from the atom bomb that destroyed Hiroshima. Video: What Exploded over Russia?

Some of the surviving pieces of the Chelyabinsk bolide fell to the ground. But the explosion also deposited hundreds of tons of dust up in the stratosphere, allowing the NASA-NOAA Suomi National Polar-orbiting Partnership satellite to make unprecedented measurements of how the material formed a thin but cohesive and persistent stratospheric dust belt.

“We wanted to know if our satellite could detect the meteor dust,” said Gorkavyi, of NASA’s Goddard Space Flight Center in Greenbelt, Md., who led the study, which has been accepted for publication in the journal Geophysical Research Letters. “Indeed, we saw the formation of a new dust belt in Earth’s stratosphere, and achieved the first space-based observation of the long-term evolution of a bolide plume.”

Gorkavyi and colleagues combined a series of satellite measurements with atmospheric models to simulate how the plume from the bolide explosion evolved as the stratospheric jet stream carried it around the Northern Hemisphere.

About 3.5 hours after the initial explosion, the Ozone Mapping Profiling Suite instrument’s Limb Profiler on Suomi detected the plume high in the atmosphere at an altitude of about 40 km, quickly moving east at about 300 kph (190 mph).

The day after the explosion, the satellite detected the plume continuing its eastward flow in the jet and reaching the Aleutian Islands. Larger, heavier particles began to lose altitude and speed, while their smaller, lighter counterparts stayed aloft and retained speed – consistent with wind speed variations at the different altitudes.

By Feb. 19, four days after the explosion, the faster, higher portion of the plume had snaked its way entirely around the Northern Hemisphere and back to Chelyabinsk. But the plume’s evolution continued: At least three months later, a detectable belt of bolide dust persisted around the planet.

The scientists’ model simulations, based on the initial Suomi NPP observations and knowledge about stratospheric circulation, confirmed the observed evolution of the plume, showing agreement in location and vertical structure.

“Thirty years ago, we could only state that the plume was embedded in the stratospheric jet stream,” said Paul Newman, chief scientist for Goddard’s Atmospheric Science Lab. “Today, our models allow us to precisely trace [the dust from] the bolide and understand its evolution as it moves around the globe.”

The full implications of the study remain to be seen. Every day, tens of metric tons of small material from space encounters Earth and is suspended high in the atmosphere. Even with the addition of the Chelyabinsk debris, the environment there remains relatively clean. Particles are small and sparse, in contrast to a stratospheric layer just below where abundant natural aerosols from volcanoes and other sources collect.

Still, with satellite technology now capable of more precisely measuring tiny atmospheric particles, scientists can embark on new studies in high-altitude atmospheric physics. How common are previously unobservable bolide events? How might this debris influence stratospheric and mesospheric clouds?

Scientists previously knew that debris from an exploded bolide could make it high into the atmosphere. In 2004, scientists on the ground in Antarctica made a single lidar observation of the plume from a 1,000-ton bolide.

“But now in the space age, with all of this technology, we can achieve a very different level of understanding of injection and evolution of meteor dust in atmosphere,” Gorkavyi said. “Of course, the Chelyabinsk bolide is much smaller than the ‘dinosaurs killer,’ and this is good: We have the unique opportunity to safely study a potentially very dangerous type of event.”

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

A meteor weighing 10,000 metric tons exploded 14 miles above Chelyabinsk, Russia, on Feb. 15, 2013. Unlike similar past events, this time scientists had the sensitive instruments on the Suomi NPP satellite to deliver unprecedented data and help them track and study the meteor plume for months. Play the video

Earth From 900 Million Miles

Posted on 2013/07/23 by admin

NASA’s Cassini spacecraft captured the color images of Earth and the moon from its perch in the Saturn system nearly 900 million miles (1.5 billion kilometers) away. MESSENGER, the first probe to orbit Mercury, took a black-and-white image from a distance of 61 million miles (98 million kilometers) as part of a campaign to search for natural satellites of the planet.

In the Cassini images Earth and the moon appear as mere dots — Earth a pale blue and the moon a stark white, visible between Saturn’s rings. It was the first time Cassini’s highest-resolution camera captured Earth and its moon as two distinct objects.

It also marked the first time people on Earth had advance notice their planet’s portrait was being taken from interplanetary distances. NASA invited the public to celebrate by finding Saturn in their part of the sky, waving at the ringed planet and sharing pictures over the Internet. More than 20,000 people around the world participated.

“We can’t see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19,” said Linda Spilker, Cassini project scientist, at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Cassini’s picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth.”

Pictures of Earth from the outer solar system are rare because from that distance, Earth appears very close to our sun. A camera’s sensitive detectors can be damaged by looking directly at the sun, just as a human being can damage his or her retina by doing the same. Cassini was able to take this image because the sun had temporarily moved behind Saturn from the spacecraft’s point of view and most of the light was blocked.

A wide-angle image of Earth will become part of a multi-image picture, or mosaic, of Saturn’s rings, which scientists are assembling. This image is not expected to be available for several weeks because of the time-consuming challenges involved in blending images taken in changing geometry and at vastly different light levels, with faint and extraordinarily bright targets side by side.

“It thrills me to no end that people all over the world took a break from their normal activities to go outside and celebrate the interplanetary salute between robot and maker that these images represent,” said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. “The whole event underscores for me our ‘coming of age’ as planetary explorers.”

In the MESSENGER image, Earth and the moon are less than a pixel, but appear very large because they are overexposed. Long exposures are required to capture as much light as possible from potentially dim objects. Consequently, bright objects in the field of view become saturated and appear artificially large. (To view the MESSENGER images, visit: http://go.nasa.gov/16Vnt5G)

“That images of our planet have been acquired on a single day from two distant solar system outposts reminds us of this nation’s stunning technical accomplishments in planetary exploration,” said MESSENGER Principal Investigator Sean Solomon of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y. “And because Mercury and Saturn are such different outcomes of planetary formation and evolution, these two images also highlight what is special about Earth. There’s no place like home.”

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

Solar Radiation Storms

Posted on 2013/05/16 by admin

Solar radiation storms continue. It takes about two days for the effects to reach Earth.

A solar flare is a sudden brightening observed over the Sun’s surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy (about a sixth of the total energy output of the Sun each second or 160,000,000,000 megatons of TNT equivalen.) They are mainly followed by a colossal coronal mass ejection also known as a CME. The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event.

X-rays and UV radiation emitted by solar flares can affect Earth’s ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb operation of radars and other devices operating at these frequencies.

The radiation risks posed by coronal mass ejections are a major concern in discussions of a manned mission to Mars, the moon, or other planets. Energetic protons can pass through the human body, causing biochemical damage,[10] presenting a hazard to astronauts during interplanetary travel. Some kind of physical or magnetic shielding would be required to protect the astronauts. Most proton storms take at least two hours from the time of visual detection to reach Earth’s orbit. A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured,[11] giving astronauts as little as 15 minutes to reach shelter.

Region 1748 has been quiet but current analysis shows it still has the potential for more large events. SWPC forecasters are watching this region very carefully as it rotates further on the disk and into a more geoeffective position.

A CME, from the X1 flare on 15 May, is expected to arrive here late on 17 May but very little effects are forecast.

Space Debris and Data Security

Posted on 2013/04/30 by admin

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Committed to promoting safety and transparency in the space domain, U.S. Strategic Command maintains a registry of tens of thousands of man-made objects in space and shares the information freely with anyone who seeks it through a command-run website.

Air Force Space Command, recognizing that collisions could damage orbiting satellites and cause more space junk, started the database as a pilot program before turning the project over to Stratcom in 2010, said Air Force Col. Lina Cashin, Stratcom’s division chief for space, cyber and deterrence policy and security cooperation.

The project, which involves regular tracking of old rocket bodies, debris and about 1,000 active satellites, has become one of Stratcom’s most universally popular products, Cashin said.

Space-Track.org has 85,000 account holders in 185 countries.

In addition to providing basic satellite catalog data to all account holders, Stratcom provides more advanced data services on request. The command also has agreements in place with 35 commercial companies to expedite information-sharing, and hopes to enter similar agreements with space-faring nations to better support their space operations, Cashin said.

Space situational awareness is crucial to Stratcom’s efforts to understand what is going on in space and to cope with the increasing amount of space debris, she explained.

Both the National Space Policy and the National Security Space Strategy call on the United States to be a leader in sharing satellite positional information to the greatest extent possible, Cashin said.

“We think that providing more transparency on the data that we have to satellite owners and operators — whether they are commercial, intergovernmental or foreign entities — promotes a more stable environment in space,” Cashin said.

“We want to share information with the rest of the world that we think can help them, and in turn help us be more responsible space operators.”

The registry serves a two-fold mission for those with satellites in orbit or planning to launch them, she explained. Nations and commercial companies can tap basic satellite data to plan space launches that won’t collide with objects already in space. And in the event that one of their satellites comes dangerously close to another object, Stratcom provides emergency notification so they can adjust course, if necessary.

During 2012, the command provided orbital data to 90 commercial and foreign organizations and 180 U.S. entities, Air Force Gen. C. Robert Kehler, Stratcom’s commander, reported to Congress last month.

“We received nearly 500,000 satellite observations and screened over 1,000 active satellites on a daily basis,” he told the Senate and House armed services committees. Based on those screenings, he said, the command issued more than 10,000 warnings of potential collisions, supported 75 “avoidance maneuvers” to prevent them and filled more than 300 requests for orbital data from 85 entities.

“Those numbers will go [up] every year,” Kehler told Congress. He emphasized the need for improvements to Stratcom’s space situational awareness capabilities and established “rules of the road” that govern behavior in space and allow the command to detect problems as they occur.

Space has changed dramatically since the Russians launched Sputnik in 1957, Cashin said. Sixty nations are now considered “space-faring,” with others anxious to join them to take advantage of the communication, navigation and other capabilities satellites and other space-based assets provide.

That makes space situational awareness more important than ever before in what Cashin characterized as an increasingly congested, competitive and contested domain.

In addition to the tens of thousands of fist-size manmade objects Stratcom regularly monitors, those too small to be tracked with current sensors could reach into the hundreds of thousands, she said.

The collision of an Iridium Communication Inc. satellite and a Russian Kosmos satellite in 2009 generated some 2,200 pieces of trackable debris. China’s anti-satellite test in 2007 generated more than 4,500 pieces — more than 3,000 of them still in orbit, and many to remain so for hundreds of years, Cashin said.

Meanwhile, space is increasingly competitive as more countries, civilian agencies and commercial companies jockey for an advantage within increasingly limited real estate.

Particularly coveted is the area of geosynchronous orbit at an altitude of about 22,000 miles directly over the equator, explained Air Force Brig. Gen. David Thompson, Stratcom’s deputy director for global operations. This orbit provides the best location for communications satellites, all requiring separation from other satellites to prevent interference.

“Those specific spots and those orbits are increasingly scarce, increasingly expensive and increasingly sought-after,” Thompson said.

That’s made space more contested as users want to take advantage of what it offers — and sometimes deny others’ access in the process.

Kehler told Congress he’s made a priority of ensuring that space capabilities that have become integral to the American way of warfare are available “whenever and wherever they are needed.”

The general also emphasized the importance of promoting trust and collaboration in space, a global common shared by nations and nongovernmental space operators around the globe.

Cashin reiterated the importance of promoting trust and collaboration in space.

“We are shifting to be completely transparent and share with our allies and partners so we can promote a … safe and stable space environment that benefits us all,” Cashin said. “As space becomes increasingly congested, competitive and contested, collaboration with our allies is more important now than ever before.”

By Donna Miles, from www.defense.gov
American Forces Press Service

Human Asteroid Initiative

Posted on 2013/04/12 by admin

NASA’s FY2014 budget proposal includes a plan to robotically capture a small near-Earth asteroid and redirect it safely to a stable orbit in the Earth-moon system where astronauts can visit and explore it.

Performing these elements for the proposed asteroid initiative integrates the best of NASA’s science, technology and human exploration capabilities and draws on the innovation of America’s brightest scientists and engineers. It uses current and developing capabilities to find both large asteroids that pose a hazard to Earth and small asteroids that could be candidates for the initiative, accelerates our technology development activities in high-powered solar electric propulsion and takes advantage of our hard work on the Space Launch System rocket and Orion spacecraft, helping to keep NASA on target to reach the President’s goal of sending humans to Mars in the 2030s.

When astronauts don their spacesuits and venture out for a spacewalk on the surface of an asteroid, how they move and take samples of it will be based on years of knowledge built by NASA scientists and engineers who have assembled and operated the International Space Station, evaluated exploration mission concepts, sent scientific spacecraft to characterize near-Earth objects and performed ground-based analog missions.

As early as the 1970s, NASA examined potential ways to use existing hardware to visit an asteroid to understand better its characteristics. On the International Space Station, scientific investigations and technology demonstrations are improving knowledge of how humans can live and work in space. The agency also has examined many possible mission concepts to help define what capabilities are needed to push the boundaries of space exploration.

During the early space shuttle flights and through assembly of the space station, NASA has relied on testing both in space and on Earth to try out ideas through a host of analog missions, or field tests, that simulate the complexity of endeavors in space.

Through 16 missions in the National Oceanic and Atmospheric Administration’s underwater Aquarius Reef Base off the coast of Key Largo, Fla., aquanauts have tested techniques for human space exploration. These underwater tests have been built upon the experience gained by training astronauts in the Neutral Buoyancy Laboratory at NASA’s Johnson Space Center in Houston to assemble and maintain the space station. The NASA Extreme Environment Mission Operations (NEEMO) 15 and 16 missions in 2011 and 2012, respectively, simulated several challenges explorers will face when visiting an asteroid, including how to anchor to and move around the surface of a near-Earth object and how to collect samples of it.

NASA also has simulated an asteroid mission as part of its 2012 Research and Technology Studies ground test at Johnson. During the simulation, a team evaluated how astronauts might do a spacewalk on an asteroid and accomplish other goals. While performing a spacewalk on a captured asteroid will involve different techniques than the activities performed during recent analog exercises, decisions made about ways to best sample an asteroid will be informed by the agency’s on-going concept development and past work.

Scientific missions also have investigated the nature of asteroids to provide a glimpse of the origins of the solar system. From the Pioneer 10 spacecraft, which in 1972 was the first to venture into the Main Asteroid Belt, to the Dawn mission, which recently concluded its investigations of asteroid Vesta and is on its way to the dwarf planet Ceres, NASA’s forays help us understand the origins of the solar system and inform decisions about how to conduct missions to distant planetary bodies. Scientists both at NASA and across the world also continue to study asteroids to shed light on their unique characteristics.

As NASA ventures farther into the solar system, the agency continues to simulate and evaluate operations and technical concepts for visiting an asteroid.

When Does an Asteroid Become a Meteor?

Posted on 2013/02/15 by admin

EARTH — NASA has been watching an asteroid, Asteroid 2012 DA14, fly near Earth; however, they missed another asteroid that became a meteor in Russia. An asteroid when it enters the Earth’s atmosphere. Usually, they burn up upon entry. Not this time.

A Russian health official estimated 1,000 people were injured when a 10 ton meteor exploded in the sky. A resident said, “There was panic. People had no idea what was happening. Everyone was going around to people’s houses to check if they were OK. We saw a big burst of light, then went outside to see what it was and we heard a really loud thundering sound.”

The sonic boom shattered 1,000,000 square feet of glass.

NASA says, “”According to NASA scientists, the trajectory of the Russian meteorite was significantly different than the trajectory of the asteroid 2012 DA14, making it a completely unrelated object. Information is still being collected about the Russian meteorite and analysis is preliminary at this point. In videos of the meteor, it is seen to pass from left to right in front of the rising sun, which means it was traveling from north to south. Asteroid DA14’s trajectory is in the opposite direction, from south to north.”

Earthrise On Christmas

Posted on 2012/12/24 by admin

This photo of “Earthrise” over the lunar horizon was taken by the Apollo 8 crew on December 24, 1968, showing Earth for the first time as it appears from deep space.

Astronauts Frank Borman, Jim Lovell and William Anders had become the first humans to leave Earth orbit, entering lunar orbit on Christmas Eve. In a historic live broadcast that night, the crew took turns reading from the Book of Genesis, closing with a holiday wish from Commander Borman: “We close with good night, good luck, a Merry Christmas, and God bless all of you — all of you on the good Earth.”

Earthrise: First Color Photograph of Earth

NASA Crashing Rockets Into the Moon

Posted on 2012/12/172012/12/17 by admin

PASADENA, CA. — NASA conducted a lunar surface impact mission of its twin Gravity Recovery and Interior Laboratory (GRAIL) spacecraft Monday, Dec. 17. The event was broadcast on NASA Television and streamed on the agency’s website.

The two probes hit a mountain near the lunar north pole at approximately 2:28 p.m. Monday, bringing their successful prime and extended science missions to an end.

Commentary originated from the control room at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

Data from the GRAIL twins are allowing scientists to learn about the moon’s internal structure and composition in unprecedented detail. The two probes are being sent purposely into the moon because they do not have enough altitude or fuel to continue science operations.

Last Flight for GRAIL’s Twin Spacecraft

This animation shows the final flight path for NASA’s twin Gravity Recovery and Interior Laboratory (GRAIL) mission spacecraft, which will impact the moon on Dec. 17, 2012, around 2:28 p.m. PST. Their successful prime and extended science missions now completed, the twin GRAIL spacecraft Ebb and Flow are being sent purposefully into the moon because their low orbit and fuel state precludes further scientific operations.

The animations were created from data obtained by NASA’s Lunar Reconnaissance Orbiter.

Image credit: NASA/JPL-Caltech/GSFC/ASU