Posted on by Nancy Atkinson

End of Mission: GRAIL Spacecraft Impact a Mountain on the Moon

The planned path of the GRAIL spacecrafts’ final orbit. Credit: NASA

“So long, Ebb and Flow, and we thank you,” said GRAIL project manager David Lehman of NASA’s Jet Propulsion Laboratory after the twin GRAIL spacecraft completed a planned formation-flying double impact into the southern face of 2.5-kilometer- (1.5-mile-) tall mountain on a crater rim near the Moon’s north pole. Mission team members estimate the two spacecraft were traveling at a speed of 1.7 kilometers per second (3,760 mph), and likely broke apart on impact. NASA said that most of what remains of the washing machine-sized spacecraft are probably buried in shallow craters, and the size of those craters will hopefully be determined when NASA’s Lunar Reconnaissance Orbiter is able to image the impact site in about two weeks.

NASA has honored the GRAIL team’s request to name Ebb and Flow’s impact sites after astronaut Sally Ride, who passed away earlier this year. She was America’s first woman in space and a member of the GRAIL mission team.

A simulation of the GRAIL impacts:

Impact occurred at 10:28:51 UTC (5:28:51 p.m. EST) and 10:29:21 UTC (5:29:21 p.m. EST). Right now it is night at the impact site, so sunlight should return within two weeks, enabling imaging of the site. LRO also took “before” images of the site during previous daylight orbits.

The impact marked a successful end to the GRAIL(Gravity Recovery and Interior Laboratory)mission, which in just a 90-day prime mission generated the highest-resolution gravity field map of any celestial body — including Earth — and determined the inner crust of the Moon is nearly pulverized.

“Ebb and Flow have removed a veil from the Moon,” said GRAIL principal investigator Maria Zuber during a televised commentary of the impacts today, adding that the mission will enable discoveries for years to come.

Data from GRAIL’s extended mission and main science instruments are still being analyzed, and the findings will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

GRAIL 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. The camera took more than 115,000 total images of the lunar surface, and imaging targets were proposed by middle school students from across the country and the resulting images returned for them to study.

“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 Zuber. “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.”

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.

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.

Screenshot of engineering data showing trajectory of the two GRAIL spacecraft about 2 minutes before Ebb’s impact. Via NASA TV.

“Ebb fired its engines for 4 minutes 3 seconds, and Flow fired its for 5 minutes 7 seconds,” Lehman. “It was one final important set of data from a mission that was filled with great science and engineering data.”

Launched in September 2011, Ebb and Flow had been orbiting the moon since Jan. 1, 2012. The probes were intentionally crashed into the lunar surface because they did not have sufficient altitude or fuel to continue science operations.

Posted on by Andy Tomaswick

NASA Looks Towards Next Mission to the Moon

NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) Observatory sits beside a radio frequency antenna inside an enclosure that blocks external static to detect electromagnetic emissions. Image credit: NASA Ames

With the GRAIL mission ending today, NASA is preparing for its next lunar orbiter mission, which could help pave the way for a potential future human mission to the Moon. While the Moon seems to be an ‘on-again-off-again’ potential human destination, as the GRAIL mission points out, studies of our closest neighbor in space continues to reveal surprises.

But if we are ever going to establish any sort of long-term presence on the Moon, scientists and engineers will have to understand more about the environmental conditions that they’re dealing with. Lunar dust is an environmental factor that requires much more exploration and study, as it may pose one of the biggest problems for humans on the Moon. Lunar dust is as fine as talcum powder and abrasive enough to cause long term problems to the lenses and seals central to the operation of mechanical equipment — not to mention hazards to human health — during any lengthy stay on the Moon.

Artist concept of the LADEE spacecraft in orbit at the Moon. Credit: NASA

To study this unique lunar environmental phenomenon, NASA is in the process of testing the Lunar Atmosphere and Dust Environment Explorer (LADEE) in preparations for its upcoming launch. Recently, LADEE integrated the last of its three main science instruments. The three instruments to be launched with the craft are the Ultraviolet and Visible Light Spectrometer, which will analyze the light signatures of the materials it detects on the Moon, the Neutral Mass Spectrometer, set to detect differences in what little atmosphere there is on the Moon over multiple orbits, and the Lunar Dust Experiment, which will collect and analyze any dust particles that are floating around the sparse atmosphere that LADEE will be flying in.

In addition to it’s science experiments, LADEE will be technically unique in a few ways. First, it is pioneering NASA’s Modular Common Bus architecture, which will hopefully increase the compatibility between future lunar spacecraft’s communications and power systems and thereby decrease their cost.

LADEE will also carry a “technology demonstration payload,” which will allow it to communicate with Earth using lasers rather than radio waves. This will dramatically increase the speed of information transfer between the spacecraft and its controllers, resulting in almost broadband-internet levels of data exchange. If this technology proves successful it is likely to be used on future lunar exploration missions as well.

LADEE is currently undergoing a battery of environmental tests. Acoustic, vibration, shock and thermal-vacuum test still await the spacecraft after it recently passed the electromagnetic interference test. Assuming it manages to keep its clean bill of health, the spacecraft could be launched on it’s 160 day mission as early as August 2013. With its help, humanity will have a better understanding of how to combat one of the most unfriendly aspects of the lunar environment.

More information on LADEE from NASA

Posted on by Nancy Atkinson

Apollo’s Final Footsteps, 40 years later

Image Credit: NASA/Eugene Cernan

Will there come a time when we on Earth can look up at the Moon and know that people are living there permanently?

40 years ago today, humans left the Moon for the last time during our visits during the Apollo program. Author Andrew Chaikin has been creating a series of videos on why space exploration is important, and to mark the 40th anniversary of the last human footsteps on the moon, he looks back at Apollo 17’s explorations and explains why he believes the Moon is the solar system’s “jewel in the crown,” beckoning us to return.


“The Moon is an ideal place for future astronauts to tackle the enormous challenges of living on other worlds,” Chaikin says, “a kind of outward-bound school for learning to live off-planet that is just three days away from home.”

You can see all of Chaikin’s videos here, and here’s an interview we did with Chaikin last year, “Was the Apollo Program an Anomaly?”

Additionally, read a great article the Amy Shira Teitel wrote for us last year about the Apollo 17 mission’s last Moonwalk.

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Posted on by Nancy Atkinson

Endgame: GRAIL Spacecraft to Slam into Lunar Crater Rim on December 17

The GRAIL mission will come to a dramatic end on Monday as the two spacecraft will be commanded to crash into the rim of an unnamed crater near the Moon’s north pole. This is all according to plan, as the two spacecraft are running out of fuel after being in lunar orbit since New Year’s Day 2012.

“We successfully completed our primary science mission,” said Principal Investigator Maria Zuber, “ and, frankly, in my wildest dreams I don’t think this mission could have gone any better than it has. But when you orbit a planetary body that has lumpy gravity field, you use a lot of fuel.”

On Dec. 17 at about 5:28 EST, the spacecraft dubbed Ebb will undergo a controlled impact into a 2 km high “mountain, a rim of a crater that has been buried in ejecta near north pole of the Moon (coordinates are 75.62°N, 26.63°W). About 30 seconds later Flow will impact, about 40 km apart.

Both spacecraft will hit the surface at 3,760 mph (1.7 kilometers per second). No imagery of the impact is expected because the region will be in shadow at the time.

These maps of Earth’s moon highlight the region where the twin spacecraft of NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission will impact on Dec. Image credit: NASA/GSFC

Additionally, Gruber said that while they hope the Lunar Reconnaissance Orbiter will be able to observe the impact region (at the very least image the region both before and after impact), they don’t expect to there to be a “flash” visible from Earth, and do not believe there will be a significant chance of doing science by kicking up volatiles like LCROSS did, mostly because of the GRAIL spacecraft small size (each about the size of a washing machine) and because of the low angle of impact. The spacecraft have been at a low orbit averaging about 11 km above the surface this week, to be able to map at a high resolution before the fuel ran out.

They chose a mountain-side “since we’re coming in at angle of 1.5 degrees, it would only have left “skid marks” on level surface,” Zuber said. “There was interest in the team in impacting a structure, or a wall, so we could learn about mechanical properties of a crater rim. We’ll be looking at the rim of the crater and understanding how much is intact rock and how much is broken up. It will be very low probability but high scientific payoff if it works, if any volatiles they would be liberated from the impacts.”

The twist on this observation, Zuber said, is this crater is in sunlight most of the time, so if any volatiles come out, it would be surprising.

GRAIL project manager David Lehman said that Friday morning (December 14) the spacecraft will each be executing a maneuver will targeting the impact site, that will also position them to avoid what are called “historic heritage sites,” where the US and Russians have put soft landers on the Moon.

Then they’ll turn off the science instruments, followed by a series of engineering demonstrations to help with future missions over the weekend. About 54 minutes before impact, they’ll burn the remaining fuel to complete the last maneuver.

Lehman said there is a bit of challenge in hitting the crater rim. “We need to clear a ridge and then keep from going through a gap in the rim, because otherwise it would keep going and hit the far side of the Moon.”

Lehman added he was sad to see the mission end. “I’m kind of hoping tonight that a gas station will pull up to our spacecraft and refuel it.”

During their prime mission, from March through May, Ebb and Flow collected data while orbiting at an average altitude of 34 miles (55 kilometers). Their altitude was lowered to 14 miles (23 kilometers) for their extended mission, which began Aug. 30 and sometimes placed them within a few miles of the moon’s tallest surface features.

The duo’s 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.

“It is going to be difficult to say goodbye,” said Zuber. “Our little robotic twins have been exemplary members of the GRAIL family, and planetary science has advanced in a major way because of their contributions.”

Posted on by Nancy Atkinson

One Spacecraft Captures Another in Lunar Orbit

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This is awesome! It is the first footage of one orbiting robotic spacecraft taken by another orbiting robotic spacecraft at Earth’s moon. “Flow,” one of two satellites making up NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission, captured this video of NASA’s Lunar Reconnaissance Orbiter (LRO) as it flew by at a distance of about 20 kilometers (12 miles) on May 3, 2012. LRO is the single bright pixel that moves from top left to bottom right. The Moon’s south polar region is in the background, much of which is in darkness.

This footage was taken by Flow’s “MoonKam” camera, which is an educational camera run by the GRAIL team and Sally Ride Science.

Posted on by Nancy Atkinson

Herschel Spacecraft Won’t “Bomb” the Moon, But GRAIL Will

Artist concept of Ebb and Flow, the two GRAIL spacecraft in orbit of the Moon. Credit: NASA

The Herschel space telescope is slated to be decommissioned next March as the observatory’s supply of cryogenic helium will be depleted. One idea for “disposing” of the spacecraft was to have it impact the Moon, a la the LCROSS mission that slammed into the Moon in 2009, and it would kick up volatiles at one of the lunar poles for observation by another spacecraft, such as the Lunar Reconnaissance Orbiter. However, that idea has been nixed in favor of parking Herschel in a heliocentric orbit. But don’t be disappointed if you were hoping for a little lunar fireworks. There will soon be a double-barreled event as the twin GRAIL spacecraft will impact the moon’s surface on December 17, 2012.

NASA will be providing more information about the GRAIL spacecrafts’ impacts at a briefing on Thursday, but the Gravity Recovery and Interior Laboratory (GRAIL) team said last week that they were still formulating ideas for the impact scenario, and looking at the possibility of aiming the crashes so they are within the field-of-view of instruments on LRO. The two spacecraft are running out of fuel – Principal Investigator Maria Zuber said they have to do three maneuvers every day to keep the spacecraft from slamming into the Moon on their own – and earlier this year the duo were lowered from their prime mission orbit of 55 kilometers above the Moon to 23 km, and this week were lowered to 11 km to enable even higher resolution data.

The two spacecraft have been providing unprecedented detail about the Moon’s internal structure as they send radio signals to each other and monitor any changes in distance between the two as they circle the Moon. Changes as small as 50 nanometers per second have been measured, and last week the team detailed how they were able to create the most detailed gravity map of the Moon, as well as make determinations that the Moon’s inner crust is nearly pulverized.

We’ll provide more information about the GRAIL impacts when it becomes available, but preliminary details are that the impacts will take place on Dec. 17 at 19:28 UTC (2:28 p.m. EST).

The impact by LCROSS (Lunar Crater Observation and Sensing Satellite) confirmed the presence of water ice and an array of volatiles in a permanently shadowed crater at the Moon’s South Pole, and it is expected GRAIL would be targeted for similar observations.

Artist’s concept of Herschel at the L2 libration point one million miles from Earth. Credit: ESA

The Herschel team had said earlier this year that because the cryogenic superfluid helium coolant is running out — and the spacecraft needs to be at temperatures as low as 0.3 Kelvin, or minus 459 degrees Fahrenheit to make its observations — one idea of getting rid of the spacecraft would be to impact it on the Moon. This week, they posted on the Herschel website that ‘the lunar impact option is feasible, but carries an additional cost on top of that of the heliocentric orbit option. The ESA Executive has decided that the Herschel spacecraft will be “parked” indefinitely in heliocentric orbit.”

The Herschel operational large halo orbit around L2 is unstable, and so the orbit needs regular “maintenance,” and consequently, after end-of-helium (expected in March 2013), the spacecraft will need to be “parked” somewhere else with no need of orbit maintenance.

Herschel team member Chris North told Universe Today that the mission operators needed to get some engineering tests done to determine if the Moon impact was feasible. “Basically they hand it over to engineers who do things that are considered too risky during the scientific mission itself – e.g. test the attitude control to its limits to see what it can withstand!” North said via email. He added that most people he had spoken with were all for the impact, — having it “go out in a blaze of glory.”

But, surprisingly, the costs for impact are greater than leaving it in a parking orbit for a few hundred years. It’s orbit may have to be maintained again in the future, as some estimates put it at potentially impacting Earth at some point in several hundred years.

And for anyone worried that a lunar impact by the GRAIL spacecraft will “hurt” the Moon, one look at the Moon shows that it has been hit in the past and continues to get impacted by asteroids and meteoroids, with no adverse affect to its orbit.

As LCROSS principal investigator Tony Colaprete said about the LCROSS impact, “What we’re doing with the Moon is something that occurs naturally four times a month on the Moon, whether we’re there or not. The difference with LCROSS is that it is specifically targeted at a certain spot, Cabeus crater,” and that the laws of physics mean there will be a miniscule perturbation.

Even though the Centaur rocket stage that hit the Moon was expect to kick up about 350 tons of lunar regolith, “The impact has about 1 million times less influence on the Moon than a passenger’s eyelash falling to the floor of a 747 jet during flight,” Colaprete said.

The two GRAIL spacecraft are about the size of washing machines, much smaller than the Centaur rocket, so will have less of an impact.

Posted on by Nancy Atkinson

Golden Spike to Offer Commercial Human Missions to the Moon

A proposed Golden Spike lunar lander on the Moon. Credit: Golden Spike Company

A proposed Golden Spike lunar lander on the Moon. Credit: Golden Spike Company

A group of space experts, media figures and even politicians announced today a new commercial company to bring paying passengers to the Moon. The Golden Spike Company is looking to “implement and operate a human space transportation system at commercially successful price points,” the company says on their website, focusing “on generating a sustainable human lunar exploration business that generates profits through multiple high value revenue streams.”

Initial estimates for a ticket to the Moon and back with Golden Spike are a cool $1.5 billion. But they aren’t only focusing on individuals as paying customers, but also other space companies and even governmental entities.

The people behind Golden Spike include their CEO Alan Stern, Principal Investigator for the New Horizons mission to Pluto who is also involved with several other space-related ventures such as Uwingu, former Apollo flight director Gerry Griffin, former shuttle flight director Wayne Hale and politician Newt Gingrich, who touted the idea of building colonies on the Moon while he was a US presidential candidate.

Golden Spike’s video preview:

During an announcement at the National Press Club today — made on the eve of the 40th anniversary of the launch of Apollo 17, the last human exploration of the Moon — Griffin said that a group of like-minded individuals got together and concluded that time is ripe for such exploration that could be afforded by corporations, nations and individuals. Golden Spike looks to provide turn-key services such as vehicles, mission planning, mission ops, and crew training to create a reliable and affordable lunar exploration system that will be U.S. based

Stern said they will not build new hardware but adapt crew capsules already in development and use existing infrastructure and launchers. However, they are looking to developing their own lunar spacesuits and lunar landers.

Their tentative plan is to use a series of launches where the first launch sends a lunar lander to orbit the Moon and a second launch brings the crew, which will then dock with the lander and head to the Moon.

Stern said their costs per flight are not much higher than some recent robotic lunar missions that have been flown and they will offset their costs with spaceship naming rights, media rights, and other enticements, plus they hope to have several investors as backers.

They also want to bring public along as an integral part of the mission.

“We realize this is science fiction. We intend to make it science fact,” Stern was quoted as saying.

Reportedly, Golden Spike has conferred with NASA on their plans.

While there are already a number of skeptics about this new endeavor, others see it as a step forward.

“Conquering the space frontier requires leadership at NASA and a partnership between commercial companies and governments,” stated Commercial Space Fight President Michael Lopez-Alegria. “I’m thrilled to see the Golden Spike announcement, which harnesses space leaders with years of experience to launch an exciting new private space venture. In the last few years we’ve learned that commercial space, by speaking to the dreams and aspirations of people around the world, can create new excitement for space travel, bringing us ever closer to our shared goal of sustainably extending human activity beyond Earth.”

Other board members include new-space entrepreneur Esther Dyson and Taber McCallum, co-founder and CEO of Paragon Space Development Corporation. The list of advisers for the company former NASA engineer and author Homer Hickam, Bill Richardson, who has served as U.N. ambassador, energy secretary and the governor of New Mexico, space historian and author Andrew Chaikin, former NASA flight surgeon Jonathan Clark, Nancy Conrad who is founder of The Conrad Foundation and is the widow of Apollo 12 moonwalker Pete Conrad.

Golden Spike also lists United Launch Alliance, Armadillo Aerospace, Masten Space Systems and several other space-industry companies as being involved with this new endeavor.

Golden Spike was the name given to the ceremonial spike that joined the rails of the first transcontinental railroad across the United States in 1869, which opened up the Western frontier to new opportunities.

“We’re not just about America going back to the moon; we’re about American industry and American entrepreneurial spirit leading the rest of the world to an exciting era of human lunar exploration,” said Stern in a press release. “It’s the 21st century, we’re here to help countries, companies, and individuals extend their reach in space, and we think we’ll see an enthusiastic customer manifest developing.”

See the Golden Spike website

Sources: Thanks to Jeff Foust (@jeff_foust) for live-Tweeting the press conference and to Doug Messier from Parabolic Arc for live blogging the event.

Posted on by Nancy Atkinson

Moon’s Inner Crust Almost Completely Pulverized

This image shows a highly porous crust on the lunar surface, a consequence of fractures generated by billions of years of impact cratering. Credit: NASA/JPL-Caltech/ IPGP

From looking at the Moon’s surface, we know it has taken a beating from asteroids and comets pummeling its surface. But new details from the GRAIL mission reveal the lunar interior just below the surface has been walloped as well, and is almost completely pulverized. This surprising finding, along with the discovery of deep fractures, suggests that in its first billion years, the Moon may have endured a history of massive impacts, more than previously thought. By inference, this means Earth and other terrestrial planets in the Solar System endured huge early impacts, too.

“It was known that planets were battered by impacts, but nobody had envisioned that the [Moon’s] crust was so beaten up,” said Maria Zuber, Principal Investigator for the GRAIL mission. “This is a really big surprise, and is going to cause a lot of people to think about what this means for planetary evolution.”

The new GRAIL data agrees with recent studies that suggest that the Late Heavy Bombardment may have lasted much longer than originally estimated and well into the time when early life was forming on Earth. Additionally, this “late-late” period of impacts — 3.8 billion to 2.5 billion years ago — was not for the faint of heart. Various blasts may have rivaled those that produced some of the largest craters on the Moon, and could have been larger than the dinosaur-killing impact that created the Chicxulub crater 65 million years ago.

From GRAIL’s measurements, Zuber and her team have now stitched together a high-resolution map of the Moon’s gravity (read more about it in our previous article.)

But the resulting map also reveals an interior gravitational field consistent with an incredibly fractured lunar crust. Compared to the surface, the map of the interior looks extraordinarily smooth. Except for the large impact basins, the Moon’s upper crust largely lacks dense rock structures and is instead likely made of porous, pulverized material.

This moon map shows the gravity gradients calculated by NASA’s GRAIL mission. Red and blue correspond to stronger gravity gradients. Image credit: NASA/JPL-Caltech/CSM

GRAIL’s lunar gravity map has also revealed numerous structures on the Moon’s surface that were unresolved by previous gravity maps of any planet, including volcanic landforms, impact basin rings, and many simple, bowl-shaped craters. From GRAIL’s measurements, scientists have determined that the Moon’s crust, ranging in thickness from 34 to 43 kilometers, is much thinner than planetary geologists had previously suspected. The crust beneath some major basins is nearly nonexistent, indicating that early impacts may have excavated the lunar mantle, providing a window into the interior.

“If you look at surface of the Moon and how heavily cratered it is,” said Zuber during a press briefing on Wednesday from the American Geophysical Union conference, “that tells us that all terrestrial planets looked that way, but Earth’s history is not preserved because of atmospheric and erosional processes on our planet. So, if we want to study those early periods, we need to go somewhere else, and the Moon is the perfect place for that.”

Zuber said that from finding an incredible fracturing of the Moon’s upper crust, we now know the crust of other planets likely have these same fractures as well. “We have reason to believe that the fractures on the terrestrial planets are deeper, and perhaps as in case of the Moon, even into the mantle. This effects planetary evolution, such as how planets lose heat,” she said.

Fractures also provide a pathway for fluids.

“Mars has been theorized to have an ancient ocean, and we wonder where it went,” said Zuber. “The ocean could well be underground, and we’ve seen evidence of water underground on Mars. If there were ever microbes on the surface of Mars, they could have gone very deep, so this finding opens up possibilities like that, and really opens a window to the early stages of our Solar System and just how violent a place it was.”

In addition to GRAIL’s discoveries, Zuber said another major accomplishment has been the performance of the spacecraft themselves. To achieve the mission’s science goals, the two probes, which can travel more than 200 kilometers apart, needed to be able to measure changes in the distance between them to within a few tenths of a micron per second. But GRAIL actually outperformed its measurement requirements by about a factor of five, resolving changes in spacecraft distance to several hundredths of a micron per second.

“On this mission, with two spacecraft, everything had to go perfectly twice,” Zuber says, adding proudly, “Imagine you’re a parent raising a twins, and your children sit down at the piano and play a duet perfectly. That’s how it feels.”

See an image gallery from the GRAIL mission here.

Sources: GRAIL press conference from AGU, MIT, JPL

Posted on by Nancy Atkinson

GRAIL First Results Provide Most Precise Lunar Gravity Map Yet

This map shows the gravity field of the moon as measured by NASA’s GRAIL mission. Image credit: NASA/ARC/MIT

The first science results from NASA’s twin GRAIL lunar orbiters provide incredible detail of the Moon’s interior and the highest resolution gravity field map of any celestial body, including Earth.

The Gravity Recovery and Interior Laboratory (GRAIL) data shows ancient internal structures that were previously unknown, provides details that are up to five orders of magnitude better than previous studies of the Moon, and delivers unprecedented information about the Moon’s surface and gravity field.

The twin spacecraft, nicknamed Ebb and Flow, send radio signals to each other and any changes in distance between the two as they circle the Moon are measured, down to changes as small as 50 nanometers per second. “That’s 1/ 20,000th the velocity that a snail moves,” said Maria Zuber, GRAIL Principal Investigator, speaking at the American Geophysical Union conference today.

The new gravity maps reveals an abundance of features such as tectonic structures, volcanic landforms, basin rings, crater central peaks and numerous simple, bowl-shaped craters. Data also show the moon’s gravity field is unlike that of any terrestrial planet in our solar system.

The instruments on the GRAIL spacecraft can probe inside the planet. Incredible videos released today shows an abundance of detail that the team said they are only just beginning to study.

Subtracting away the gravity from surface features provides what is called a Bouguer gravity map. What remains is a view of mass anomalies inside the Moon due to either variations in crustal thickness or mantle density. In the video above, the prominent nearside circular highs (in red) indicate the well-known mass concentrations or ‘mascons,’ but many similar newfound far-side features are also visible.

“Ninety-eight percent of local gravity is associated with topography, while 2 percent are other gravitational features,” said Zuber. “You can see bull’s-eyes of the lunar mascons, but otherwise we see a smooth inner surface. The only way this could happen is if impacts to the early Moon shattered the inner surface.”

These maps of the moon show the “Bouguer” gravity anomalies as measured by NASA’s GRAIL mission. Image credit: NASA/JPL-Caltech/CSM

The Bougeur gravity map also revealed evidence for ancient volcanic activity under the surface of the Moon and strange linear gravitational anomalies.

“In the gradients of Bouguer gravity map, saw features we didn’t expect,” said Jeff Andrews-Hanna, GRAIL co-investigator. “We identified a large population of linear gravitational anomalies. We don’t see any expression of them on topography maps, so we infer that these are an ancient internal structures.”

A linear gravity anomaly intersecting the Crisium basin on the nearside of the moon has been revealed by NASA’s GRAIL mission. The GRAIL gravity gradient data are shown at left, with the location of the anomaly indicated. Red and blue correspond to stronger gravity gradients. Topography data over the same region from NASA’s Lunar Reconnaissance Orbiter’s Lunar Orbiter Laser Altimeter are shown at right; these data show no sign of the gravity anomaly. Credit: NASA/JPL-Caltech/CSM

For example, this image of Crisium Basin, which forms one of the ‘man on moon’s’ eyes, the gravity maps shows a linear feature crossing the basin while topography maps show no such correlating feature. “This tells us the gravity anomaly formed before the impacts,” Andrews-Hanna said.

These maps of the near and far side of the moon show the gravity gradients as measured by NASA’s GRAIL mission, highlighting a population of linear gravity anomalies. Image credit: NASA/JPL-Caltech/CSM

Additional data reveal that the Moon’s inner crust in almost completely pulverized. Read more about it in our second article on the new GRAIL results.

Other data reveal the crust of the Moon is thinner than previously thought.

“Using GRAIL gravity data, we found the average thickness of the crust is 32-34 kilometers which is about 10 km less than previous studies,” said Mark Wieczorek, GRAIL Co-Investigator. “We found the bulk abundance of aluminum on Moon is nearly the same as that of the Earth. This is consistent with a recent hypothesis that the Moon is derived of materials from the Earth when it was formed during a giant impact event.”

NASA’s GRAIL mission took this flyover video above the Mare Orientale basin of Earth’s moon. It was collected by the MoonKAM aboard GRAIL’s Ebb spacecraft on April 7 and 8, 2012. Movie credit: NASA/JPL-Caltech/Sally Ride Science

During its prime mission, the two GRAIL spacecraft orbited just 55 km above the Moon’s surface. This close distance is why GRAIL is producing the best gravity field data for any planet, including Earth.

“GRACE is still collecting great data about Earth’s gravity field, but because Earth has an atmosphere, GRACE has to orbit at 500 km,” said Zuber. “Nothing beats going low.”

Zuber said the GRAIL team learned from GRACE and were able to make “some judicious improvements.” She also suggested this technology should be used for every planetary body in the solar system, and threw out an enticing idea: “Imagine mapping currents beneath the surface of Europa,” she said.

GRAIL finishes the primary science mission in May and are currently working in an extended mission where the spacrafts’ altitude was lowered to just 23 km above the surface. “We are opening another window interms of geophysics, and so you’ll be hearing results from the new data sets soon,” said Sami Asmar, GRAIL team member.

At a AGU conference session later in the day, Zuber revealed that tomorrow, December 6, 2012, the team will lower the GRAIL spacecraft down to just 11 km above the lunar surface.

Artist concept of GRAIL mission, with two twin spacecraft in tandem orbits around the moon to measure its gravity field in unprecedented detail. Image credit: NASA/JPL

The extended mission will end soon, in mid-December, and soon after that, the two spacecraft will be crashed intentionally onto the lunar surface. The team said today that they are still formulating ideas for the impact scenario, and looking at the possibility of aiming the crashes so they are within the field-of-view of instruments on NASA’s Lunar Reconnaissance Orbiter.

Posted on by Nancy Atkinson

40 Years After Apollo, the Moon Still Beckons

A lunar mining facility harvests oxygen from the resource-rich volcanic soil of the eastern Mare Serenitatis.Credit: NASA/Pat Rawlings

40 years ago this week, the final Apollo mission, Apollo 17, launched to the Moon. In this new video produced by author Andrew Chaikin, geologist Paul Spudis of the Lunar and Planetary Institute explains why the Moon still beckons, “not just to visit, not just put a footprint there, but to go and understand it, to collect its rock and understand its history, to recover a lost chapter of a previous existence.” Right now, we understand just a small part of the history of our Solar System, and the Moon holds that history in its rocks. Additionally, newly found water on the Moon — estimates say about 600 million metric tons could be at the lunar poles — could allow us to “live off the land” in space.

A lunar mining facility harvests oxygen from the resource-rich volcanic soil of the eastern Mare Serenitatis. Credit: NASA/Pat Rawlings.