Spectacular high Sun view of the Mare Tranquillitatis pit crater revealing boulders on an otherwise smooth floor. Image is 400 meters wide, north is up, NAC M126710873R [NASA/GSFC/Arizona State University].
As promised, the Lunar Reconnaissance Orbiter is taking more detailed looks at the lunar pits, or lava tubes that have been discovered by LRO and the Kaguya spacecraft. These are deep holes on the moon that could open into vast underground tunnels, and could serve as a safe, radiation shielding habitats for future human lunar explorers. Plus, they are just plain intriguing! This image of a pit found in the Sea of Tranquility (Mare Tranquillitatis) was taken as the Sun was almost straight overhead, illuminating the region. By comparing this image with previous images that have different lighting, scientists can estimate the depth of the pit. They believe it to be over 100 meters!
See more “in-depth” look at more of the caves on the Moon, below:
Two views of Mare Ingenii pit Credit: NASA/GSFC/Arizona State University.
These two images show a pit in Mare Ingenii, which reveal different portions of the floor as the Sun crosses from west to east. Again, by measuring the shadows in different lighting, the Sea of Cleverness pit appears to be about 70 meters deep and about 120 meters wide.
These long, winding lava tubes are like structures we have on Earth. They are created when the top of a stream of molten rock solidifies and the lava inside drains away, leaving a hollow tube of rock. There have been hints that the Moon had lava tubes based on observations of long, winding depressions carved into the lunar surface by the flow of lava, called sinuous rilles.
If a human geologist could ever climb down inside these tubes on the Moon, we could learn so much about the Moon’s history, and sort of travel back in time by studying the different layers on the Moon, just like we do on Earth.
Three views of the Marius Hills pit. Credit: NASA/GSFC/Arizona State University.
LROC has now imaged the Marius Hills pit three times, each time with very different lighting. The center view has an incidence angle of 25° that illuminates about three-quarters of the floor. The Marius pit is about 34 meters deep and 65 by 90 meters wide.
Read more about the Ingenii, Tranquillitatis, and Marius pits at the LROC website, and you can search the nearby area for clues in the full LROC NAC frame that may help determine if an extended lava tube system still exists beneath the surface.
The night sky on August 27, 2010. Image from EarthSky.org
[/caption]
I wasn’t going to write an article about the Mars-Moon Hoax this year because I thought it was too passé — we’ve written articles about this email-circulated fallacy every year since 2003 and another article would be like beating a dead horse because surely, there’s no one out there anymore that actually believes Mars can look as big as the full Moon.
But I just looked at some stats and saw that our article on the topic from 2007, “Will Mars Look as Big as the Full Moon On August 27? Nope” has gotten like a gazillion hits the past few days, so obviously people are Googling the topic, wondering if Mars will look as big as the full Moon tonight.
Short answer: No. If you looked at the night sky last night, Mars was not as big as the full Moon then, and it won’t be that big tonight. Moreover, it won’t be that big, ever. It is impossible for Mars to ever look as big as the full Moon. And this year (2010) in August, Mars is just barely visible, as a faint object low in the west after sunset. Take a look at the sky chart above from EarthSky.org which shows you where it is. And you can read more about Mars in 2010 at the EarthSky.org website, which is a great resource for all sorts of science topics and is written by some of the world’s top scientists.
The confusion arises from an erroneous and completely hoaxy email that started in 2003 when Mars was about as close to Earth it will ever get, but still, it was very far away, about 55,758,006 kilometers (34,646,418 miles). It did not look as big as the full Moon then, and it certainly never will. Take a look at JPL’s blog post, “Five Things About Viewing Mars in August” written by outreach specialist Jane Houston Jones. She writes:
“The moon is one-quarter the size of Earth and is relatively close — only about 384,000 kilometers (about 239,000 miles) away. On the other hand, Mars is one-half the size of Earth and it orbits the sun 1-1/2 times farther out than Earth’s orbit. The closest it ever gets to Earth is at opposition every 26 months. The last Mars opposition was in January and the next one is in March 2011.
At opposition, Mars will be 101 million kilometers (63 million miles) from Earth, almost twice as far as in 2003. So from that distance, Mars could never look the same as our moon.”
NASA usually writes an article about this every year as well — and this year it is called “The Mutating Mars Hoax.”
Every year, Universe Today has been debunking the erroneous email that has been going around since 2003. If you’d like to look back, here are a few: 2009, 2008, 2007, 2006, and 2005. If you don’t believe Fraser and me, Phil Plait the Bad Astronomer debunks the email here, here , here, and here’s the original one back in 2003.
The first quarter moon is actually the third phase of the moon each cycle. In the Northern Hemisphere during this phase, the right hand 50% of the moon is visible during the afternoon and the early part of the night. In the Southern Hemisphere the left hand 50% of the moon can be seen. This lunar phase follows the new moon and the waxing crescent.
A lunar phase is the appearance of an illuminated portion of the moon as seen by an observer. For this article the observer is always on Earth. The lunar phases vary in a definite cycle as the moon orbits the Earth. The phases change based on the changing relative positions of the Earth, moon, and Sun. Half of the moon’s surface is always illuminated by the Sun, but the portion of the illuminated hemisphere that is visible to an observer can vary from 100%(full moon) to 0%(new moon). The only exception is during a lunar eclipse. The boundary between the light and dark portions of the moon is called the terminator.
There are 8 moon phases. These phases are: new moon, waxing crescent, first quarter moon, waxing gibbous, full moon, waning gibbous, last quarter moon, and waning crescent. The phases progress in the same manner each month. Earlier, it was mentioned that the lunar phase depends on the position of the Earth, moon, and Sun. During the new moon the Earth and Sun are on the opposite side of the moon. During the full moon the Earth and Sun are on the same sides of the Moon. The occasions when the Earth, Sun, and moon are in a straight line(new and full moon) are called syzygies.
When the moon passes between Earth and the Sun during a new moon, you might think that its shadow would cause a solar eclipse. On the other hand, you might think that during a full moon the Earth’s shadow would cause a lunar eclipse. The plane of the moon’s orbit around the Earth is tilted by about five degrees compared to the plane of Earth’s orbit around the Sun(called the ecliptic plane). This tilt prevents monthly eclipses. An eclipse can only occur when the moon is either new or full, but it also has to be positioned near the intersection of the Earth’s orbital plane about the Sun and the Moon’s orbit plane about the Earth, so there are between four and seven eclipses in a calendar year.
The first quarter moon is only one of eight lunar phases. You should research them all for a better understanding of the Earth/Moon system.
We have written many articles about the phases of the moon for Universe Today. Here’s an article about the 8 phases of the moon, and here’s an article about the moon phases for 2010.
Earth and Moon from 114 Million Miles.Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
[/caption]
A new image to add to the family photo album! The MESSENGER spacecraft is working its way to enter orbit around Mercury in March of 2011, and while wending its way, took this image of the Earth and Moon, visible in the lower left. When the image was taken in May 2010, MESSENGER was 183 million kilometers (114 million miles) away from Earth. For context, the average separation between the Earth and the Sun is about 150 million kilometers (93 million miles). It’s a thought provoking image (every one of us is in that image!), just like other Earth-Moon photos — Fraser put together a gallery of Earth-Moon images from other worlds, and this one will have to be added. But this image was taken not just for the aesthetics.
This image was taken as part of MESSENGER’s campaign to search for vulcanoids, small rocky objects hypothesized to exist in orbits between Mercury and the Sun. Though no vulcanoids have yet been detected, the MESSENGER spacecraft is in a unique position to look for smaller and fainter vulcanoids than has ever before been possible. MESSENGER’s vulcanoid searches occur near perihelion passages, when the spacecraft’s orbit brings it closest to the Sun. August 17, 2010 was another such perihelion, so if MESSENGER was successful in finding any tiny asteroids lurking close to the Sun, we may hear about it soon.
mages from Moon Zoo showing trails from tumbling boulders in the Montes Alpes/Vallis Alpes region on the Moon. Credit: NASA/LRO/Moon Zoo.
[/caption]
There’s probably a great story in this image, if only someone was there to witness it as it happened! This is an image from Moon Zoo, the citizen science project from the Zooniverse that asks people to look at images from the Lunar Reconnaissance Orbiter and search for craters, boulders and more. And often, the Zooites find some very interesting features on the Moon, like this one and the ones below that include tracks from rolling, bounding, tumbling and sometimes bouncing boulders. Then the task for the scientists is to figure out what actually happened to get these boulders moving — was it an impact, are the boulder on the bottom of a hill, or was it some other unknown catalyst? As Zooniverse founder Chris Lintott says, “The Moon has its own landscape that is really quite dramatic, so it’s a world well worth exploring.”
LRO image from Moon Zoo.
Why look for tumbling boulders? Moon Zoo scientist Dr. Katie Joy gave this explanation:
“One of the main reasons we are asking Moon Zoo users to search for scars left behind by tumbling boulders is to help support future lunar exploration initiatives. Boulders that have rolled down hillsides from crater walls, or massifs like the Apollo 17 landing site, provide samples of geologic units that may be high up a hillside and thus difficult to access otherwise by a rover or a manned crew vehicle. If mission planning can include traverses to boulders that have rolled down hills, and we can track these boulders back up to the part of hillside from where they have originated, it provides a neat sampling strategy to accessing more geological units than would have been possible otherwise… Thus we hope to use Moon Zoo user data to produce a map of known boulder tracks (and terminal boulders) across the Moon.”
If you want to join in on the fun of looking for mysteries on the Moon, check out Moon Zoo, or the Zooniverse for more citizen science projects where you can get involved in helping scientists do real science.
Hadley Rille, the landing site for Apollo 15. Credit: NASA
[/caption]
With all the recent news of water on the Moon, a new paper published today in the journal Science may offer a surprise – or it may bring us back to previous assumptions about the Moon. A new analysis of eleven lunar samples from the Apollo missions by Zachary Sharp from the University of New Mexico and his colleagues indicates that when the Moon formed, its interior was essentially dry. While the recent findings of ubiquitous water and hydroxyl on the surface as well as water ice in the lunar poles are not challenged by this new finding, it does dispute — somewhat — two other recent papers that proposed a wetter lunar interior than previously thought. “The recent LCROSS findings were of water on the lunar surface due to cometary impacts, and the ice is from the comets themselves,” Sharp told Universe Today. “We are talking about water that was present in the molten early Moon 4.5 billion years ago.”
The accepted theory of how the Moon formed is that a Mars-sized body slammed into our early Earth, creating a big disk of debris that would ultimately form into the Moon.
Although planetary scientists are still refining models of the Moon’s formation, there is much to suggest a dry Moon. Any water would have been vaporized by the high temperatures generated by the impact and cataclysm that followed, and vapor would have escaped into space. The assumption is that the only way there could be water in the Moon’s interior if is the impactor was especially water-rich, and also if the Moon solidified quickly, which is considered unlikely.
But earlier this year, Francis McCubbin and his team from the Carnegie Institution for Science released their findings of a surprisingly high abundance of water molecules — as high as several thousand parts per million — bound to phosphate minerals within volcanic lunar rocks, which would have formed well beneath the lunar surface and date back several billion years.
Additionally, in 2008, Alberto Saal of Brown University and colleagues found a slightly lower abundance of water in the lunar mantle, but it was significantly higher than the previous estimate of 1 part per billion.
These two findings have been pushing lunar scientists to find possible alternative explanations for the Moon’s formation to account for all the water.
But now, Sharp and his team studied a wide range of lunar basalts and measured the composition of chlorine isotopes. Using gas source mass spectrometry they found a wide range of chlorine isotopes contained in the samples which are 25 times greater than what is found in rocks and minerals from Earth and from meteorites.
Chlorine is very hydrophilic, or attracted to water, and is an extremely sensitive indicator of hydrogen levels. Sharp and his team say that, if lunar rocks had initial hydrogen contents anywhere close to those of terrestrial rocks, then the fractionation of chlorine into so many different isotopes would never have happened on the Moon. Because of this Sharp and his colleagues say their results suggest a very dry interior of the Moon.
Sharp proposes that Saal and McCubbin’s calculations of high hydrogen contents in some lunar samples are not typical, and perhaps those samples are the product of certain igneous processes that resulted in their “extremely volatile enrichment.” They do not, however, represent the high and variable isotopic chlorine values reported in the majority of lunar rocks, Sharp said.
Still, there could be a compromise between the varied findings. “There are uncertainties that one has to take into account when doing this type of study, ” Sharp told Universe Today, “and if we take the low estimates of Saal and McCubbin’s papers, they are not so different from our findings.”
But the discrepancies, however small, show that perhaps we can’t make generalizations about the entire Moon from limited samples.
“We have not yet looked for water in a wide range of lunar samples,” said Jeff Taylor from the University of Hawaii, who was not involved in any of the aforementioned studies. “It is quite possible that the initial differentiation of the Moon and subsequent processes such as mantle overturn concentrated whatever water the Moon had into certain areas. Until we measure more samples, including samples from the farside (represented by many of the lunar meteorites and eventually by sample-return missions), we will not know for sure how much water is in the bulk Moon.”
In combination, all the recent studies of the lunar surface show there is likely a complex chemistry on the Moon that we have yet to understand.
“In other words,” said Taylor, “we need more work!”
High-resolution view from LRO of an unusual crater near Moon’s north pole, Rozhdestvensky (110 miles, or 177 kilometers in diameter). Credit: NASA
[/caption]
Radar has been used since the 1960s to map the lunar surface, but until recently it has been difficult to get a good look at the Moon’s poles. In 2009, the Mini-SAR radar instrument on the Chandrayaan-1 spacecraft was able to map more than 95% of both poles at 150 meter radar resolution, and now the Mini-RF instrument on the Lunar Reconnaissance Orbiter — which has 10 times the resolution of the Mini-SAR — is about halfway through its first high-resolution mapping campaign of the poles. The two instruments are revealing there are likely massive amounts of water in the permanently shadowed craters at the poles, with over 600 million metric tons at the north pole alone. “If that was turned into rocket fuel, it would be enough to launch the equivalent of one Space Shuttle per day for over 2,000 years,” said Paul Spudis, principal investigator for the Mini-SAR, speaking at the annual Lunar Forum at the Ames Research Center in July.
Both Spudis and Ben Bussey, principal investigator for LRO’s Mini-RF shared images from their respective instruments at the Forum, highlighting polar craters that exhibit unusual radar properties consistent with the presence of ice.
They have found over 40 craters on the Moon’s north pole that exhibit these properties.
Both instruments provide details of the interior of shadowed craters, not able to be seen in visible light. In particular, a measurement called the circular polarization ratio (CPR) shows the characteristics of the radar echoes, which give clues to the nature of the surface materials in dark areas. The instruments send pulses of left-polarized radio waves to measure the surface roughness of the Moon. While smooth surfaces send back a reversed, right-polarized wave, rough areas return left-polarized waves. Ice, which is transparent to radio waves, also sends back left-polarized waves. The instruments measure the ratio of left to right circular polarized power sent back, which is the CPR.
Few places – even in our solar system — have a CPR greater than 1 but such places have thick deposits of ice, such as Martian polar caps, or the icy Galilean satellites. They are also seen in rough, rocky ejecta around fresh, young craters, but there, scientists also observe high CPR outside the crater rim such as in this image, below of the Main L crater on the Moon.
The fresh impact crater Main L (14 km diameter), which shows high CPR inside and outside its rim. The histograms at right show that the high CPR values within (red line) and outside the crater rim (green line) are nearly identical. Credit: NASA
Most of the Moon has low CPR, but dozens of anomalous north pole craters, such as a small 8 km crater within the larger Rozhdestvensky crater, had a high CPR on the inside, with a low CPR on the rims. That suggests some material within the craters, rather than surface roughness, caused the high CPR signal.
“Geologically, we don’t expect rough, fresh surfaces to be present inside a crater rim but absent outside of it,” Spudis said. “This confirms the high CPR in these anomalous craters is not caused by surface roughness, and we interpret this to mean that water ice is present in these craters.” An “anomalous” crater on the floor of Rozhdestvensky, near the north pole of the Moon. The histogram of CPR values clearly shows that interior points (red line) have higher CPR values than those outside the crater rim (green line). Credit: NASA
Additionally, the ice would have to be several meters thick to give this signature. “To see this elevated CPR effect, the ice must have a thickness on the order of tens of wavelengths of the radar used,” he said. “Our radar wavelength is 12.6 cm, therefore we think that the ice must be at least two meters thick and relatively pure.”
Recent Mini-SAR images (top image) from LRO confirm the Chandrayaan-1 data, with even better resolution. The Mini-RF, Bussey said, is equivalent to a combination of the Arecibo Observatory and the Greenbank Radio telescope in looking at the Moon. “Our polar campaign will map from 70 degrees to the poles and so far we are very pleased with the coverage and quality of the data,” Bussey said.
Spudis said they are seeing less anamolous craters on the Moon’s south pole, but both he and Bussey are looking forward to comparing more data between the two radar instruments to learn more about the permanently shadowed craters on the Moon.
Additionally, other instruments on LRO will also provide insights into the makeup of these anomalous craters.
This schematic shows the daytime cycle of hydration, loss and rehydration on the lunar surface. Credit: University of Maryland/McREL.
[/caption]
“Water cycle on the Moon” is a phrase that many people – including lunar scientists – were never expecting to hear. This surprising new finding of ubiquitous water on the surface of the Moon, revealed and confirmed by three different spacecraft last year, has been one of the main topics of recent discussion and study by lunar researchers. But figuring out the cycle of how water appears and disappears over the lunar day remains elusive. As of now, scientists suspect a few different processes that could be delivering water and hydroxyl (OH) to the lunar surface: meteorites or comets hitting the Moon, outgassing from the Moon’s interior, or the solar wind interacting with the lunar regolith. But so far, none of the details of any of these processes are adding up.
Dana Hurley from The Johns Hopkins University Applied Physics Laboratory is part of team of scientists attempting to model the lunar water cycle, and she discussed the work at the NASA Lunar Science Institute’s third annual Lunar Forum at Ames Research Center, July 20-22, 2010.
“When we do the model, we assume the way that the water is lost is through photodissociation, and so that sets the timescale,” Hurley told Universe Today. “And using that timescale the amount that is coming in through the solar wind or micrometeorites can’t add up to the amount observed if it is in steady state, so something is not jiving.”
Photodissociation involves the breaking up of a substance into simpler components by the radiant energy of sunlight.
It appears the amount of water varies over the course of the lunar day. Two observations a week apart by a spectrometer on the repurposed Deep Impact spacecraft (now called EPOXI) showed the region that was near the Moon’s terminator at dawn had a detectable amount of water and hydroxyl, and a week later when it was near noon, those substances were gone. But the new region at dawn then had H2O and OH.
One theory holds that the water and hydroxyl are, in part, formed from hydrogen ions in the solar wind. By local noon, when the moon is at its warmest, some water and hydroxyl are lost. By evening, the surface cools again, and the water and hydroxyl return.
But, Hurley said, the solar wind in steady state does not reproduce the observed surface density of water and hydroxyl.
Additionally, looking at the other possible sources — the known source rate of micrometeoroids and comets — doesn’t provide the amount of observed H20 and OH either.
“We’d really like to have a lot more observations to understand how it evolves over the course of the day,” Hurley said. Water in Polar Regions on the Moon Credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS
In her talk, Hurley said her team has been trying to look at all possible angles and ideas, including recent larger comet hits on the Moon, or potentially a seasonal event where water deposited at winter poles could be released when it warms up in summer. But so far none of these ideas have been tested or modeled, and as of now do not provide a solution to the daily cycle of water that was observed.
She also noted that since there are obviously some unique processes going on, the interaction between the surface and atmosphere needs more study.
“The surface and atmosphere are coupled,” Hurley said in an interview with Universe Today. “The atmosphere is produced from the surface; there is no atmosphere that lasts for a long time on the Moon and it is constantly being produced and lost. And so it is coming from the surface, either from something that is coming from the lunar regolith grains or something that is interacting with those grains, whether it is solar wind or something that is impacting. So, the surface is the source of the atmosphere and that atmosphere comes back and interacts with the surface again. And you really have to understand that whole system.”
So, what is her best guess as to the source of the water?
Hurley said there has to be some sort of recycling going on within the regolith, and perhaps a complex surface chemistry that allows the H20 and OH to exist for longer periods of time, which would better explain the surface density.
“What I’ve looked at is what could be happening in the atmosphere and how things hop around from the surface up and then back down to the surface,” she said. “The lunar regolith is rather loose, and these small particles and gases can go down within the regolith and be within the top several centimeters and work their way down and back out. So there is an exchange going on in that top layer that is kind of acting as a reservoir. That is my best guess of what is going on.”
If there’s only one thing we’ve learned from all the highly successful recent Moon missions – the Lunar Reconnaissance Orbiter, LCROSS, Chandrayaan-1 and Kaguya — it’s that the Moon is perplexingly different from our perceptions of the past 40 years. The discovery of water and volatiles across the surface and in the permanently shadowed regions at the poles changes so many of the notions we’ve had about Earth’s constant companion. Basically, just within the past year we’ve realized the Moon is not a dry, barren, boring place, but a wetter, richer and more interesting destination than we ever imagined. And so, the proposal for NASA to effectively turn away from any human missions to the Moon, as well as Administrator Charlie Bolden’s ‘been there, done that’ comments is quite perplexing – especially for the lunar scientists who have been making these discoveries.
“It’s been quite a year for the Moon,” said Clive Neal, a lunar geologist from Notre Dame, speaking last week at the NASA Lunar Science Institute’s annual Lunar Forum at Ames Research Center. “And things got quite depressing around February 2010.”
That’s when President Obama proposed a new budget that effectively would end the Constellation program and a return to the Moon.
At the Forum, lunar scientists shared their most recent findings – as well as their attempts to model and comprehend all the data that is not yet understood. But they saved any discussion of NASA’s future until the final presentation of the meeting.
“Hopefully this talk will stop you from running out of here ready to hang yourself or slit your wrists,” quipped Neal, who led the final session.
The week began, however, with keynote speaker Andrew Chaikin – author of the Apollo ‘bible,’ “A Man on the Moon,” and several other space-related books — saying, “We have to erase that horrendous ‘been there done that’ notion.” Chaikin also shared a famous Peanuts cartoon showing Lucy pulling the football out from under from Charlie Brown. No caption was needed for everyone to understand to what Chaikin was referring.
“With all of these new discoveries, we should have ample reason to believe that humans will follow,” said Chaikin. But right now, he added, the man in the Moon looks a little like Rodney Dangerfield. “The Moon wants – and deserves – respect.”
“It appears NASA’s focus might be shifting to Near Earth Objects,” said Neal, “but the Moon is the nearest Near Earth Object. It’s quicker, safer and cheaper to get humans there, and the important thing to recognized that there’s a lot left to explore, and a lot to do on the Moon.”
Only 5% of the Moon’s surface has been explored by humans, and Neal showed scaled maps of the Apollo landing sites overlaid on maps of Africa, Europe and the US, revealing just how small a portion of the Moon has been explored directly by humans. The map below shows the Apollo 11 crew’s movement on the Moon can fit within the size of a soccer (football) field.
Apollo 11 VS. a soccer (football) field. Credit: NASA History website. Click for larger version.
Additionally, the latest data reveal that the Apollo sites were in no way representative of the entire Moon.
In light of the proposed plan to give up on the Moon, Neal said there probably is a lot of misperceptions by the American public, as well as in other countries that there’s nothing to do or learn at the Moon. But he believes nothing could be further from the truth.
“What we’ve heard over the last couple of days are fantastic talks and seen wonderful posters in regard to the vibrancy of lunar exploration and science, and seen that exploration enables science and that science enables exploration. The Moon is a Rosetta Stone for solar system exploration and science. The recognition of a possible lunar magma ocean has resulted in terrestrial and Martian magma oceans being proposed. This could be the way terrestrial planets evolve and the Moon is begging us to go back and explore to figure that out.”
There’s also the studies of preserved impacts on the lunar surface which represents a look back in time where we can figure out how to do date planetary surfaces, test cataclysm hypotheses, and study how airless bodies undergo space weathering, which has a direct application to NEO research. Studying cold trap deposits has direct applicability to learning more about the planet Mercury, and lunar regolith contains information about the history of our Sun.
There are proposals for doing radio astronomy from the lunar farside, which will probe the dark ages of the Universe and look back to when the first stars turned on. “So the Moon is a gateway to the Universe,” Neal said. “You can do so much more with the moon — its not just the moon, it’s the solar system and beyond.”
In addition there are many unresolved scientific questions about the Moon. What are the locations and origins of shallow Moon quakes, and large lunar seismic events? How does the lunar regolith affect transmission of seismic energy? What is the nature of the lunar volatiles in the permanently shadowed regions at the lunar poles? What is the mechanism for the adsorption of water, hydroxyl and other minerals recently found on the Moon’s surface? What is nature of lunar core?
When Constellation was proposed, returning to the Moon was said to be a testbed for going on to Mars. It would be a safe and more economical way to test out systems and technology needed for going to the Red Planet. So, what has changed?
Primarily the budget. There weren’t enough funds in Constellation’s coffers to go to the Moon and then Mars. It primarily became a Moon-only program, which many said, didn’t bring us to the “real” destination that everyone really wants: Mars.
And money is still the real issue for not returning to the Moon in the new proposals of going to NEO’s and then Mars. If money weren’t an object, we’d do it all.
But the Moon offers a great local to test out human missions to Mars. “The Moon offers one-sixth of Earth’s gravity,” Neal said,” and we do not know what happens to the human body over time in that gravity, and we can only extrapolate what happens there and on Mars’ one-third gravity. We could test out life support, the growth of crops, the radiation environment and more. The ‘feed forward’ there is quite important where you can simulate a Mars mission on Moon. To develop and test your radiation shielding in the real environment on the Moon is more of a test than flying on the space station.”
Both Neal and Chaikin said they could go on and on about the benefits of returning to the Moon, and they also book-ended the Lunar Forum by saying it is up to the lunar scientists and Moon enthusiasts to educate the public, other scientists and even NASA about the importance of the Moon.
“We have to do a better job of educating the public – even dealing with the conspiracy theorists,” Neal said. “We need to get into schools and educate about what NASA has done, and what they are doing now. We all take responsibility for that.”
“The Moon is not going to get the respect it deserves unless people are out there talking about it,” said Chaikin.
A. Light microscopy image of 72255,89. (B) Higher magnification image of transition from light to dark material in area shown in (A). (C) Raman spectra of three types of graphite analyzed in the sample. Credit: A. Steele, et al.
[/caption]
Long-held secrets continue to be unlocked from the Moon. Researchers taking a new look at a rock brought back by the Apollo 17 mission have discovered graphite in the form of tiny whiskers within the lunar sample. Just like the recent finding of water on the Moon, it was previously thought that any carbon present in the Apollo rocks came from terrestrial contamination from the way the lunar samples were collected, processed or stored. Andrew Steele, who led a team from the Carnegie Institution’s Geophysical Laboratory said the graphite could have come from carbonaceous impactors that struck both the Moon and Earth during the Late Heavy Bombardment, approximately 4.1 to 3.8 billion years ago, and if so, could provide a new and important source of information about this period in the solar system’s early history.
“We were really surprised at the discovery of graphite and graphite whiskers,” Steele said. “We were not expecting to see anything like this.”
The tiny graphite whiskers or needles were found in multiple spots within a specific area of lunar sample 722255 from the Mare Serenitatis impact crater in the Taurus-Littrow region, indicating that the minerals are in fact from the Moon and not just contamination.
Steele told Universe Today that he and his team don’t think the graphite originated on the Moon, but haven’t ruled it out completely.
“Our initial thought is that it is from the impactor, as we find it in a very fine grained impact melt breccias,” he said in an email. “I am currently looking in more pristine lunar rocks, i.e. lavas that do not contain evidence of meteorite material, for carbon phases.”
He added that the graphite may have come from the impactor itself, or it may have formed from the condensation of carbon-rich gas released during the impact.
The team used Raman imaging spectroscopy (CRIS) on a thin section of a freshly fractured surface of the rock. This identifies minerals and carbon species and their spatial relationship to each other beneath the surface of a sample. Steele said even though this rock has been on Earth since 1972, new techniques and instruments allowed for the new discovery.
“The analytical spot size is smaller and so we can look at smaller phases,” he said. “The sensitivity is better in the newer instruments and we can use spatially resolved methods that are much more sensitive than in the Apollo era.”
Impact breccias are made up of a jumble of smaller fragments that formed when the moon was struck by an asteroid or other object.
Other previous spectroscopy of the Moon’s surface has also found trace amounts of carbon, but it was thought to have come from the solar wind. However, Steele said he and his team have also ruled that out as the source.
“Several lines of reasoning confirm that the observed graphite and graphite whiskers (GW) are indigenous to the sample,” said the team in their paper. “In particular, all known GW synthesis methods involve deposition from a carbon-containing gas at relatively high temperatures ranging from 1273 to ~3900 K. Thus, the GWs identified in 72255 cannot have been synthesized as a result of sample handling and preparation. Moreover, they could not have been implanted by solar wind, because this carbon is typically too small to identify structurally at the magnifications used. The crystalline graphite grains detected here are likely either intact remnants of graphite and GWs from the Serentatis impactor, or they could have formed from condensation of carbon-rich gas released during impact.”
Steele said their findings indicate that impacts may be another process by which GWs can form in our solar system. Additionally, it appears carbonaceous material from impacts at the time of the Late Heavy Bombardment (LHB), and at a time when life may have been emerging on Earth, does survive on the Moon.
“The Solar System was chaotic with countless colliding objects 3.8 billion years ago,” Steele said in a press release. “Volatiles—compounds like water and elements like carbon were vaporized under that heat and shock. These materials were critical to the creation of life on Earth.”
While the impacts to Earth during that period have since been erased, craters on the Moon are still pristine, so the Moon potentially holds a record of the meteoritic carbon input to the Earth-Moon system, when life was just beginning to emerge on Earth.
The research is published in the July 2, 2010, issue of Science.
