Posted on by Nancy Atkinson

Book Review: The Final Journey of the Saturn V

Book review by David L. Hamilton

The Final Journey of the Saturn V, by Andrew R. Thomas and Paul N. Thomarios is a good book to add to this summer’s reading list. The nontechnical person should not be deterred by the title since the majority of the book covers the history of the rocket and the space race while the final chapter covers some of the details about the restoration process of the deteriorated Saturn V that weathered outside of Kennedy Space Center Florida for over a decade.

The authors do a great job explaining that during the Cold War the Soviet Union started to surpass the United States in in terms of rocketry and space exploration. For example, the Soviets launched the first satellite into Earth orbit, sent a probe to the Moon, launched the first rocket carrying a man that orbited the Earth, launched the first rocket carrying a woman that orbited the Earth and launched a rocket carrying the first man that walked in space.
All these first by the Soviets had a profound effect on Americans who finally realized that if the United States was going to have an influence in space exploration, they needed to get busy. And busy they got.

After a challenge from President Kennedy to put a man on the Moon and safely return him before the end of the 1960’s and a cash infusion from the United States government, NASA expanded operations that employed over 400,000 individuals who worked for NASA and its many subcontractors. The Saturn V rockets that would take over a dozen men to the moon and launch Skylab into orbit is the end result of the money, manpower and determination that drove the United States of America to take the lead in the space race after the slow start and second place status it held for several years.

Sadly, after making it to the moon several times the public grew tired of NASA and the Moon missions so funding for NASA dried up. Jobs were lost and equipment was neglected and misplaced. Locating and restoring the equipment and preserving it for future generations is covered in the last chapter.

Authors Thomas and Thomarios do a great job of keeping the book nontechnical so that the causal reader who has no science background can easily understand and enjoy it while keeping it interesting enough for the more experienced reader who specializes in the history of space flight.

A real plus for this book is an impressive foreword written by Captain Gene Cernan, Commander of Apollo 17 and the last man to have walked on the Moon. In addition to the foreword, there are many unique photographs ranging from those that made the Moon landings possible to the equipment involved and those in charge of restoring the Saturn V for our future generations.

See more information about the book at the University of Akron Press webpage.

Reviewer David Hamilton and his wife live in Conway, Arkansas. They are amateur astronomers that love spending nights stargazing. David is an Educational Technologist and a multidisciplinary researcher currently attending the University of Arkansas at Little as a graduate student. David is an alumni of the University of Oklahoma and Rose State College.

Posted on by Jason Major

A New Look at Apollo Samples Supports Ancient Impact Theory

Apollo 16 astronaut Charlie Duke collects lunar samples during EVA on April 23, 1972 (NASA)

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New investigations of lunar samples collected during the Apollo missions have revealed origins from beyond the Earth-Moon system, supporting a hypothesis of ancient cataclysmic bombardment for both worlds.

Samples of Apollo 16 breccia that contain chondritic material (JSC)

Using scanning electron microscopes, researchers at the Lunar-Planetary Institute and Johnson Space Center have re-examined breccia regolith samples returned from the Moon, chemically mapping the lunar rocks to discern more compositional detail than ever before.

What they discovered was that many of the rocks contain bits of material that is chondritic in origin — that is, it came from asteroids, and not from elsewhere on the Moon or Earth.

Chondrites are meteorites that originate from the oldest asteroids, formed during the development of the Solar System. They are composed of the initial material that made up the stellar disk, compressed into spherical chondrules. Chondrites are some of the rarest types of meteorites found on Earth today but it’s thought that at one time they rained down onto our planet… as well as our moon.

The Lunar Cataclysm Hypothesis suggests that there was a period of extremely active bombardment of the Moon’s surface by meteorite impacts around 3.9 billion years ago. Because very few large impact events — based on melt rock samples — seem to have taken place more than 3.85 billion years ago, scientists suspect such an event heated the Moon’s surface enough prior to that period to eradicate any older impact features — a literal resurfacing of the young Moon.

There’s also evidence that there was a common source for the impactors, based on composition of the chondrites. What event took place in the Solar System that sent so much material hurtling our way? Was there a massive collision between asteroids? Did a slew of comets come streaking into the inner solar system? Were we paid a brief, gravitationally-disruptive visit by some other rogue interstellar object? Whatever it was that occurred, it changed the face of our Moon forever.

Curiously enough, it was at just about that time that we find the first fossil evidence of life on Earth. If there’s indeed a correlation, then whatever happened to wipe out the Moon’s oldest craters may also have cleared the slate for life here — either by removing any initial biological development that may have occurred or by delivering organic materials necessary for life in large amounts… or perhaps a combination of both.

Timeline for the Lunar Cataclysm Hypothesis (LPI)

The new findings from the Apollo samples provide unambiguous evidence that a large-scale impact event was taking place during this period  on the Moon — and most likely on Earth too. Since the Moon lacks atmospheric weathering or water erosion processes it serves as a sort of “time capsule”, recording the evidence of cosmic events that take place around the Earth-Moon neighborhood. While evidence for any such impacts would have long been erased from Earth’s surface, on the Moon it’s just a matter of locating it.

In fact, due to the difference in surface area, Earth may have received up to ten times more impacts than the Moon during such a cosmic cataclysm. With over 1,700 craters over 20 km identified on the Moon dating to a period around 3.9 billion years ago, Earth should have  17,000 craters over 20 km… with some ranging over 1,000 km! Of course, that’s if the craters could had survived 3.9 billion years of erosion and tectonic activity, which they didn’t. Still, it would have been a major event for our planet and anything that may have managed to start eking out an existence on it. We might never know if life had gained a foothold on Earth prior to such a cataclysmic bombardment, but thanks to the Moon (and the Apollo missions!) we do have some evidence of the events that took place.

Sample of lunar impact melt breccia, showing exterior and chondrule-filled interior. (Click for sample report.) Source: JSC

The LPI-JSC team’s paper was submitted to the journal Science and accepted for publication on May 2. See the abstract here, and read more on the Lunar Science Institute’s website here.

And if you want to browse through the Apollo lunar samples you can do so in depth on the JSC Lunar Sample Compendum site.

Posted on by Nancy Atkinson

Viewing Alert: New Interview Series with Neil Armstrong

Apollo 11 landing site. Credit: NASA

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There’s a new four-part interview series with Apollo astronaut Neil Armstrong, and part 1 is now available for viewing. The first man to walk on the Moon gives a personal commentary on Apollo 11’s historic lunar landing, his thoughts on leadership and taking risks to innovate for the future. With the future of NASA’s program currently under scrutiny, throughout the series Armstrong will talk about his position on the policy direction of the space agency, speaks candidly on his early life, and even tackles conspiracy theorist claims that the Moon landing never happened – using images from Google Moon to demonstrate their path. The series also includes previously unseen footage of the lunar descent. Armstrong doesn’t give many interviews, and the show’s producers say this is the first on-camera interview Armstrong has done since 2005. The episodes are from evoTV’s series, The Bottom Line.

The different parts will be released over the next few weeks:

Part 1 – Space Race: now available

Part 2 – Blast Off available 8 May

Part 3 – Giant Leap available 15 May

Part 4 – Presidential Pride available 22 May

Posted on by Nancy Atkinson

‘Seeing’ Cosmic Rays in Space

The Apollo Light Flash Moving Emulsion Detector (ALFMED), an experiment to record of incidents cosmic ray particles hitting astronauts. Credit: NASA

Astronauts have long reported the experience of seeing flashes while they are in space, even when their eyes are closed. Neil Armstrong and Buzz Aldrin both reported these flashes during the Apollo 11 mission, and similar reports during the Apollo 12 and 13 missions led to subsequent Apollo missions including experiments specifically looking at this strange phenomenon. These experiments involved blindfolding crewmembers and recording their comments during designated observation sessions, and later missions had a special device, the Apollo Light Flash Moving Emulsion Detector (ALFMED), which was worn by the astronauts during dark periods to record of incidents of cosmic ray hits.

It was determined the astronauts were ‘seeing’ cosmic rays zipping through their eyeballs. Cosmic rays are high-energy charged subatomic particles whose origins are not yet known. Fortunately, cosmic rays passing through Earth are usually absorbed by our atmosphere. But astronauts outside the atmosphere can find themselves “seeing things that aren’t there,” wrote current International Space Station astronaut Don Pettit, who told about his experience of seeing these flashes on his blog:

“In space I see things that are not there. Flashes in my eyes, like luminous dancing fairies, give a subtle display of light that is easy to overlook when I’m consumed by normal tasks. But in the dark confines of my sleep station, with the droopy eyelids of pending sleep, I see the flashing fairies. As I drift off, I wonder how many can dance on the head of an orbital pin.”

In a report on the Apollo experiment, astronauts described the types of flashes they saw in three ways: the ‘spot’, the ‘streak’, and the ‘cloud’; and all but one described the flashes as ‘white’ or ‘colorless.’ One crewmember, Apollo 15 Commander David Scott, described one flash as “blue with a white cast, like a blue diamond.”

Pettit described the physics/biology of what takes place:

“When a cosmic ray happens to pass through the retina it causes the rods and cones to fire, and you perceive a flash of light that is really not there. The triggered cells are localized around the spot where the cosmic ray passes, so the flash has some structure. A perpendicular ray appears as a fuzzy dot. A ray at an angle appears as a segmented line. Sometimes the tracks have side branches, giving the impression of an electric spark. The retina functions as a miniature Wilson cloud chamber where the recording of a cosmic ray is displayed by a trail left in its wake.”

Pettit said that the rate or frequency at which these flashes are seen varies with orbital position.

“There is a radiation hot spot in orbit, a place where the flux of cosmic rays is 10 to 100 times greater than the rest of the orbital path. Situated southeast of Argentina, this region (called the South Atlantic Anomaly) extends about halfway across the Atlantic Ocean. As we pass through this region, eye flashes will increase from one or two every 10 minutes to several per minute.

A cosmic ray hit on a camera appears as a segmented line in the image. Credit: NASA/Don Pettit..

During the Apollo missions, astronauts saw these flashes after their eyes had become dark-adapted. When it was dark, they reported a flash every 2.9 minutes on average. Only one Apollo crewmember involved in the experiments did not report seeing the phenomenon, Apollo 16’s Command Module Pilot Ken Mattingly, who stated that he had poor night vision.

These cosmic rays don’t just hit people, but things in space, too, and sometimes cause problems. Pettit wrote:

“Free from the protection offered by the atmosphere, cosmic rays bombard us within Space Station, penetrating the hull almost as if it was not there. They zap everything inside, causing such mischief as locking up our laptop computers and knocking pixels out of whack in our cameras. The computers recover with a reboot; the cameras suffer permanent damage. After about a year, the images they produce look like they are covered with electronic snow. Cosmic rays contribute most of the radiation dose received by Space Station crews. We have defined lifetime limits, after which you fly a desk for the rest of your career. No one has reached that dose level yet.”

The Phantom Torso experiment, AKA, Fred. Credit: NASA

There are experiments on board the ISS to monitor how much radiation the crew is receiving. One experiment is the Phantom Torso, a mummy-looking mock-up of the human body which determines the distribution of radiation doses inside the human body at various tissues and organs.

There’s also the Alpha Magnetic Spectrometer experiment, a particle physics experiment module that is mounted on the ISS. It is designed to search for various types of unusual matter by measuring cosmic rays, and hopefully will also tell us more about the origins of both those crazy flashes seen in space, and also the origins of the Universe.

A tall order!

Posted on by Jason Major

Why Are Lunar Shadows So Dark?

A lunar boulder peeks out into the sunlight. (NASA/GSFC/Arizona State University)

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A lunar boulder catches the last edge of the setting sunlight in this image from the Lunar Reconnaissance Orbiter Camera. The boulders litter the floor of an unnamed 3.5 km wide (2.17 mile wide) crater located within the much larger crater Lobachevskiy. The smaller crater’s rim casts its shadow along the left side of the image, and raises the question: why are shadows on the Moon so dark?

On Earth, air scatters light and allows objects not in direct sunlight to be still well-lit. This is an effect called Rayleigh scattering, named for the British Nobel-winning physicist Lord Rayleigh (John William Strutt.) Rayleigh scattering is the reason why the sky is blue, and (for the most part) why you can still read a magazine perfectly well under an umbrella at the beach.

On the Moon there is no air, no Rayleigh scattering. So shadows are very dark and, where sunlight hits, very bright. Shadowed areas are dramatically murky, like in the LROC image above, yet there’s still some light bouncing around in there — this is due to reflected light from the lunar surface itself.

Buzz was well-lit by reflected light, even in Eagle's shadow. (NASA/Apollo Image Archive)

Lunar regolith is composed of fine, angular particles of very reflective dust. It tends to reflect light directly back at the source, and will illuminate objects within shadows as well — as seen in Apollo mission photographs. Astronauts within the shadow of the landing modules were still visible, and their suits were well illuminated by reflected light from the lunar surface. Some people have used this as “proof” that the landings were actually filmed on a sound stage under artificial lights, but in reality it’s all due to reflected light.

Here’s a great run-though of the lunar landing photos and how lighting on the Moon works.

So even though air isn’t scattering the sunlight on the Moon, there’s still enough reflection to sneak light into the shadows… but not much. It gets dark — and quickly cold — in there!

And if you’re one of those who likes to get a better look into the shadows, here’s the same image above with the dark areas brightened enough to see details:

Shadow world revealed! (NASA/GSFC/Arizona State University/J. Major)

Some interesting boulder trails in there!

See this image on Arizona State University’s LROC news page here, and zoom into the full NAC scan here.

Posted on by Irene Antonenko

If the Moon Currently has Liquid Magma, Why isn’t it Erupting?

A new look at old data has given scientists more insight into the Moon's core. Credit: Science

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Last year, scientists took another look at the seismic data collected by Apollo era experiments and discovered that the lower mantle of the Moon, the part near the core-mantle boundary, is partially molten (e.g., Apollo Data Retooled to Provide Precise Readings on Moon’s Core, Universe Today, Jan. 6, 2011). Their findings suggest that the lowest 150 km of the mantle contains anywhere from 5 to 30% liquid melt. On the Earth, this would be enough melt for it to separate from the solid, rise up, and erupt at the surface. We know that the Moon had volcanism in the past. So, why is this lunar melt not erupting at the surface today? New experimental studies on simulated lunar samples may provide the answers.

It is suspected that the current lunar magmas are too dense, in comparison to their surrounding rocks, to rise to the surface.  Just like oil on water, less dense magmas are buoyant and will percolate up above the solid rock. But, if the magma is too dense, it will stay where it is, or even sink.

Motivated by this possibility, an international team of scientists, led by Mirjam van Kan Parker from the VU University Amsterdam, has been studying the character of lunar magmas. Their findings, which were recently published in the Journal Nature Geoscience, show that lunar magmas have a range of densities that are dependent on their composition.

Ms van Kan Parker and her team squeezed and heated molten samples of magma and then used X-ray absorption techniques to determine the material’s density at a range of pressures and temperatures. Their studies used simulated lunar materials, since lunar samples are considered too valuable for such destructive analysis. Their simulants modelled the composition of Apollo 15 green volcanic glasses (which have a titanium content of 0.23 weight %) and Apollo 14 black volcanic glasses (which have a titanium content of 16.4 weight %).

Samples of these simulants were subjected to pressures up to 1.7 GPa (atmospheric pressure, at the surface of the Earth, is 101 kPa, or 20,000 times less than what was achieved in these experiments). However, pressures in the lunar interior are even greater, exceeding 4.5 GPa. So, computer calculations were conducted to extrapolate from the experimental results.

Apollo 15 green glass beads
Apollo 15 green glass beads. Credit: NASA

The combined work shows that, at the temperatures and pressures typically found in the lower lunar mantle, magmas with low titanium contents (Apollo 15 green glasses) have densities that are less than the surrounding solid material. This means they are buoyant, should rise to the surface, and erupt. On the other hand, magmas with high titanium contents (Apollo 14 black glasses) were found to have densities that are about equal to or greater than their surrounding solid material. These would not be expected to rise and erupt.

Since the Moon has no active volcanic activity, the melt currently located at the bottom of the lunar mantle must have a high density. And, Ms van Kan Parker’s results suggest that this melt should be made of high titanium magmas, like those that formed the Apollo 14 black glasses.

A new look at old data has given scientists more insight into the Moon's core. Credit: Science

This finding is significant, because high titanium magmas are thought to have formed from titanium-rich source rocks. These rocks represent the dregs that were left at the base of the lunar crust, after all the buoyant plagioclase minerals (which make up the crust) had been squeezed upwards in a global magma ocean. Being dense, these titanium-rich rocks would have quickly sunk to the core-mantle boundary in an overturn event. Such an overturn even had been postulated over 15 years ago. Now, these exciting new results provide experimental support for this model.

These dense, titanium-rich rocks are also expected to have a lot of radioactive elements, which tend to get left behind when other elements are preferentially taken up by mineral crystals. The resulting radiogenic heat from the decay of these elements could explain why parts of the lower lunar mantle are still hot enough to be molten. Ms van Kan Parker and her team further speculate that this radiogenic heat could also be helping to keep the lunar core partially melted even today!

Sources:
X-Rays Illuminate the Interior of the Moon, Science Daily, Feb. 19, 2012.
Neutral buoyancy of titanium-rich melts in the deep lunar interior, van Kan Parker et al. Nature Geoscience, Feb. 19, 2012, doi:10.1038/NGEO1402.

Posted on by Ken Kremer

China Unveils High Resolution Global Moon Map

China Publishes High Resolution Full Moon map from Chang'e-2 Lunar Orbiter. Chinese scientists assembled a full moon map using images captured by the Chang’e-2 spacecraft with an an unprecedented resolution of 7-meters. Credit: China Space Program

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Chinese scientists have assembled the highest resolution map ever created of the entire Moon and unveiled a series of global Moon images on Monday, Feb. 6.

The composite Lunar maps were created from over 700 individual images captured by China’s Chang’e-2 spacecraft and released by the country’s State Administration of Science, Technology and Industry for National Defence (SASTIND), according to reports from the state run Xinhua and CCTV new agencies.

“The map and images are the highest-resolution photos of the entirety of the Moon’s surface to be published thus far,” said Liu Dongkui, deputy chief commander of China’s lunar probe project, reports Xinhua.

Of course there are much higher resolution photos of numerous individual locations on the Moon taken from orbit by the spacecraft of other countries and from the surface by NASA’s Apollo lunar landing astronauts as well as unmanned Russian & American lunar landers and rovers.

China unveils High Resolution Global Moon map from Chang'e-2 Lunar Orbiter
Credit: China Space Program

Chang’e-2 is China’s second lunar probe and achieved orbit around our nearest neighbor in space in October 2010. It was launched on Oct. 1, 2010 and is named after a legendary Chinese moon goddess.

The images were snapped between October 2010 and May 2011 using a charge-coupled device (CCD) stereo camera as the spacecraft flew overhead in a highly elliptical orbit ranging from 15 km to 100 km altitude.

The Chang’e-2 maps have a resolution of 7 meters, which is 17 times greater than from China’s first lunar orbiter; Chang’e-1, launched in 2007.

Global Lunar Map from China’s Chang'e-2 Lunar Orbiter. Credit: China Space Program

In fact the maps are detailed enough that Chinese scientists were able to detect traces of the Apollo landers, said Yan Jun, chief application scientist for China’s lunar exploration project.


Chang’e-2 also captured high resolution photos of the “Sinus Iridum”area , or Bay of Rainbows, where China may land their next Moon mission. The camera had the ability to resolve features as small as 1 meter across at the lowest altitude.

The satellite left lunar orbit in June 2011 and is currently orbiting the moon’s second Lagrange Point (L2), located more than 1.5 million km away from Earth.

Chinese space program officials hope for a 2013 liftoff of the Chang’e-3 lunar rover, on what would be China’s first ever landing on another celestial body. China’s next step beyond the rover may be to attempt a lunar sample return mission in 2017.

Demonstrating the ability to successfully conduct an unmanned lunar landing is a key milestone that must be achieved before China can land astronauts on the Moon, perhaps within the next decade.

NASA’s twin GRAIL spacecraft recently achieved Lunar orbit over the New Year’s weekend. The duo of probes were just renamed as “Ebb and Flow” – the winning entries in an essay naming contest submitted by 4th Grade US students from Bozeman, Montana.

At this time NASA does not have the funding or an approved robotic lunar landing mission, due to severe budget cuts.And even worse NASA cuts will be announced shortly !

Russia hopes to send the Lunar Glob spacecraft to land on the Moon around 2015.

Since the United States has unilaterally scuttled its plans to return American astronauts to the Moon’s surface, it’s very possible that the next flag planted on the Moon by humans will be Chinese.

Posted on by Amy Shira Teitel

The Thirty-Ninth Anniversary of the Last Moonwalk

Image Credit: NASA/Eugene Cernan

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On December 13, 1972, Apollo 17 Commander Eugene A. Cernan and Lunar Module Pilot (LMP) Harrison H. “Jack” Schmitt made the final lunar EVA or moonwalk of the final Apollo mission. Theirs was the longest stay on the Moon at just over three days and included over twenty-two hours spent exploring the lunar surface during which they collected over 250 pounds of lunar samples.

To commemorate the thirty-ninth anniversary of this last EVA, NASA posted a picture of Schmitt on the lunar surface as its ‘Image of the Day.’ 

Apollo 17, the only lunar mission to launch at night. Image Credit: NASA/courtesy of nasaimages.org

Apollo 17 launched on a Saturn V rocket on December 7, 1972. Four days later on December 11, Cernan and Schmitt moved into the Lunar Module Challenger and descended to a touchdown in the Taurus-Littrow valley. Command Module Pilot Ron Evans, meanwhile, stayed in orbit aboard the Command Module America.

The Taurus-Littrow valley was chosen as the best landing spot to take advantage of Apollo 17’s capabilities. It was a “J mission,” one designed for extended EVAs that would take the astronauts further from the LM than any previous missions using the Lunar Rover. It was also a geologically interesting area. Here, the astronauts would be able to reach and collect samples from the old lunar highlands as well as relatively young volcanic regions. For this latter goal, Apollo 17’s greatest tool was its LMP, Schmitt.

When NASA began looking for its first group of astronauts in 1959, candidates had to be affiliated with the military, trained engineers, and have logged at least 1,500 hours of flying time in jets. The same basic criteria were applied to the second and third group of astronauts selected in 1962 and 1963 respectively.

Cernan's Apollo 17 lunar suit is currently on display at the Smithsonian National Air and Space Museum, just one of the 137 million Apollo-era artifacts in the museum's collection. Image Credit: National Air and Space Museum

The fourth group brought a change. In June 1965, six trained scientists joined NASA’s astronaut corps. For this group, PhDs were a necessity and the previous flight hours requirement was dropped. Three of the men selected were physicists, two were physicians, and one, Schmitt, was a trained geologist.

Schmitt had explored the geological possibilities of a a lunar mission as a civilian. Before he joined NASA, he worked with the U.S. Geological Survey’s Astrogeology Center in Flagstaff, Arizona. There he devised training programs designed to teach astronauts enough about geology as well as photographic and telescopic mapping to make their journeys to the Moon as fruitful as possible. He was among the astrogeologists that instructed NASA’s astronauts during their geological field trips.

After joining the astronaut corps, Schmitt spent 53 weeks catching up to his colleagues in flight proficiency. He also spent hundreds of hours learning to fly both the Lunar Module and the Command Module. All the while, he remained an integral part of the astronauts’ lunar geology training, often assisting crews in finding and collecting the right kinds of rocks from a control station in Houston during a lunar mission.

Schmitt’s lunar companion, Gene Cernan, was an Apollo veteran. As the LMP on Apollo 10, he had flown within eight miles of the lunar surface but didn’t have enough fuel — or NASA’s blessing — to actually land. As commander of Apollo 17, he spent more time on the Moon than any other man. As commander, he entered the LM after Schmitt at the end of their final moonwalk. His bootprints remain the most recent human-made mark on the lunar surface.

Cernan and Schmitt abord the LM Challenger during their Apollo 17 mission. Image Credit: NASA/courtesy of nasaimages.org
Posted on by Jason Major

How the Moon Became Magnetized

astronauts faced possible radiation dangers on the Moon.
Apollo 17 astronaut Harrison "Jack" Schmitt at Tracy Rock on the lunar surface. If a solar storm had hit the Moon while the astronauts were on the surface exploring, it could have been a disaster. Credit: NASA.

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It’s been a mystery ever since the Apollo astronauts brought back samples of lunar rocks in the early 1970s. Some of the rocks had magnetic properties, especially one collected by geologist Harrison “Jack” Schmitt. But how could this happen? The Moon has no magnetosphere, and most previously accepted theories state that it never did. Yet here we have these moon rocks with undeniable magnetic properties… there was definitely something missing in our understanding of Earth’s satellite.

Now a team of researchers at the University of California, Santa Cruz thinks they may have cracked this enigmatic magnetic mystery.

In order for a world to have a magnetic field, it needs to have a molten core. Earth has a multi-layered molten core, in which heat from the interior layer drives motion within the iron-rich outer layer, creating a magnetic field that extends far out into space. Without a magnetosphere Earth would have been left exposed to the solar wind and life as we know it could may never have developed.

Apollo 17 lunar rock sample

Simply put, Earth’s magnetic field is crucial to life… and it can imbue rocks with magnetic properties that are sensitive to the planet-wide field.

But the Moon is much smaller than Earth, and has no molten core, at least not anymore… or so it was once believed. Research of data from the seismic instruments left on the lunar surface during Apollo EVAs recently revealed that the Moon may in fact still have a partially-liquid core, and based on a paper published in the November 10 issue of Nature by Christina Dwyer, a graduate student in Earth and planetary sciences at the University of California, Santa Cruz, and her co-authors Francis Nimmo at UCSC and David Stevenson at the California Institute of Technology, this small liquid core may once have been able to produce a lunar magnetic field after all.

The Moon orbits on its axis at such a rate that the same side always faces Earth, but it also has a slight wobble in the alignment of its axis (as does Earth.) This wobble is called precession. Precession was stronger due to tidal forces when the Moon was closer to Earth early in its history. Dwyer et al. suggest that the Moon’s precession could have literally “stirred” its liquid core, since the surrounding solid mantle would have moved at a different rate.

This stirring effect – arising from the mechanical motions of the Moon’s rotation and precession, not internal convection – could have created a dynamo effect, resulting in a magnetic field.

This field may have persisted for some time but it couldn’t last forever, the team said. As the Moon gradually moved further away from Earth the precession rate slowed, bringing the stirring process – and the dynamo – to a halt.

“The further out the moon moves, the slower the stirring, and at a certain point the lunar dynamo shuts off,” said Christina Dwyer.

Still, the team’s model provides a basis for how such a dynamo could have existed, possibly for as long as a billion years. This would have been long enough to form rocks that would still exhibit some magnetic properties to this day.

The team admits that more paleomagnetic research is needed to know for sure if their proposed core/mantle interaction would have created the right kind of movements within the liquid core to create a lunar dynamo.

“Only certain types of fluid motions give rise to magnetic dynamos,” Dwyer said. “We calculated the power that’s available to drive the dynamo and the magnetic field strengths that could be generated. But we really need the dynamo experts to take this model to the next level of detail and see if it works.”

In other words, they’re still working towards a theory of lunar magnetism that really sticks.

 

Read the article by Tim Stephens on the UCSC website.

 

Posted on by Jason Major

Apollo Astronaut Returns “Stolen” Camera

Apollo 14 astronaut Ed Mitchell on the Moon, February 5, 1971. Credit: NASA.

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In a follow-up to a recent Universe Today article, Apollo astronaut and sixth-man-on-the-moon Ed Mitchell has agreed to return a lunar Data Acquisition Camera (DAC) that he kept from the Apollo 14 mission, rather than face a court date next year over a suit filed by NASA in June.

The 16mm camera was “rescued” from the Apollo 14 landing module by Mitchell as it was about to be released from the orbiter after the astronauts’ visit to the Moon in February 1971. The lander – with everything remaining in it – would later crash onto the Moon’s surface.

Not only did Mitchell consider it a waste of a valuable piece of historic equipment, but there was a then-standing policy that astronauts could keep certain items from their missions as mementos.

This Data Acquisition Camera (DAC) was one of two 16mm cameras on the Apollo 14 lunar module "Antares" when it landed on the moon on Feb, 5, 1971. Credit: FLSD

Mitchell had had the DAC until May 2010, when he put it and other items up for auction at New York’s Bonhams auction house as a part of their “Space History Sale”. It was at that time that NASA filed a suit against the 80-year-old Mitchell, claiming that he had no rightful ownership of the camera. Mitchell’s attempt to get the case dismissed was denied by a Florida district court judge earlier this month, who stated that there was no statute or jurisdiction on such cases, being filed by a federally-run organization.

Rather than go to court in October 2012, Mitchell agreed in district court this past Thursday to “relinquish all claims of ownership, legal title, or dominion” over the camera.

Mitchell and the federal prosecutors will each be responsible for their own legal fees.

Read the original Universe Today story here, and for more details see the article on collectSpace.com.