Posted on by Fraser Cain

Glimpse at the Envelope of a Young Star

Detailed new images of the starbirth nursery in the Omega Nebula (M17) have revealed a multi component structure in the envelope of dust and gas surrounding a very young star. The stellar newborn, called M17-SO1, has a flaring torus of gas and dust, and thin conical shells of material above and below the torus. Shigeyuki Sako from University of Tokyo and a team of astronomers from the National Astronomical Observatory of Japan, the Japan Aeorospace Exploration Agency, Ibaraki University, the Purple Mountain Observatory of the Chinese Academy of Sciences, and Chiba University obtained these images and analyzed them in infrared wavelengths in order to understand the mechanics of protoplanetary disk formation around young stars. Their work is described in a detailed article in the April 21, 2005 edition of Nature.

The research team wanted to find a young star located in front of a bright background nebula and use near-infrared observations to image the surrounding envelope in silhouette, in a way comparable to how dentists use X-rays to take images of teeth. Using the Infrared Camera and Spectrograph with Adaptive Optics on the Subaru telescope, the astronomers looked for candidates in and around the Omega Nebula, which lies about 5,000 light-years away in the constellation Sagittarius. They found a large butterfly-shaped near-infrared silhouette of an envelope about 150 times the size of our solar system surrounding a very young star. They made follow-up observations of the region using the Cooled Mid-Infrared Camera and Spectrograph on the Subaru telescope and the Nobeyama Millimeter Array at the Nobeyama Radio Observatory. By combining the results from the near-infrared, mid-infrared, and millimeter wave radio observations, the researchers determined that the M17-SO1 is a protostar about 2.5 to 8 times the mass of the Sun, and that the butterfly-like silhouette reveals an edge-on view of the envelope.

The near-infrared observations reveal the structure of the surrounding envelope with unprecedented levels of detail. In particular, observations using the 2.166 emission line of hydrogen (called the Brackett gamma (Br ?) line) show that the envelope has multiple components instead of one simple structure. Around the equator of the protostar, the torus of dust and gas increases in thickness farther way from the star. Thin cone-shaped shells of material extend away from both poles of the star.

The discovery of the multi-component structure puts new constraints on how an envelope feeds material to a protostellar disk forming within its boundaries. “It’s quite likely that our own solar system looked like M17-SO1 when it was beginning to form,” said Sako. “We hope to confirm the relevance of our discovery for understanding the mechanism of protoplanetary disk formation by using the Subaru telescope to take infrared images with high resolution and high sensitivity of many more young stars.?

Original Source: NOAJ News Release

Posted on by Fraser Cain

Genesis Recovery Proceeding Well

Scientists have closely examined four Genesis spacecraft collectors, vital to the mission’s top science objective, and found them in excellent shape, despite the spacecraft’s hard landing last year.

Scientists at NASA’s Johnson Space Center (JSC) in Houston removed the four solar-wind collectors from an instrument called the concentrator. The concentrator targets collected solar-oxygen ions during the Genesis mission. Scientists will analyze them to measure solar-oxygen isotopic composition, the highest-priority measurement objective for Genesis. The data may hold clues to increase understanding about how the solar system formed.

“Taking these concentrator targets out of their flight holders and getting our first visual inspection of them is very important,” said Karen McNamara, Genesis curation recovery lead. “This step is critical to moving forward with the primary science Genesis was intended to achieve. All indications are the targets are in excellent condition. Now we will have the opportunity to show that quantitatively. The preliminary assessment of these materials is the first step to their allocation and measurement of the composition of the solar wind,” she said.

The targets were removed at JSC by a team from Los Alamos National Laboratory, Los Alamos, N.M., where the concentrator was designed and built.

“Finding these concentrator targets in excellent condition after the Genesis crash was a real miracle,” said Roger Wiens, principal investigator for the Los Alamos instruments. “It raised our spirits a huge amount the day after the impact. With the removal of the concentrator targets this week, we are getting closer to learning what these targets will tell us about the sun and our solar system,” he added.

The Los Alamos team was assisted by JSC curators and Quality Assurance personnel from NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Curators at JSC will examine the targets and prepare a detailed report about their condition, so scientists can properly analyze the collectors. The targets will be imaged in detail and then stored under nitrogen in the Genesis clean room.

Genesis was launched Aug. 8, 2001, from Cape Canaveral Air Force Station, Fla., on a mission to collect solar wind particles. Sample collection began Dec. 5, 2001, and was completed April 1, 2004. After an extensive recovery effort, following its Sept. 8, 2004, impact at a Utah landing site, the first scientific samples from Genesis arrived at JSC Oct. 4, 2004.

Original Source: NASA News Release

Posted on by Fraser Cain

Audio: Alpha, Still Constant After All These Years

Image credit: SDSS
Listen to the interview: Alpha, Still Constant After All These Years (3.3 MB)

Or subscribe to the Podcast: universetoday.com/audio.xml

Fraser Cain: Can you give me the primer on Alpha?

Jeffery Newman: So Alpha is one of the constants that describes the strength of a fundamental force; there are 4 fundamental forces: electromagnetism, the weak force, the strong force and gravity and Alpha basically determines the strength of the electromagnetic force compared to the other 4. As such, it’s a very basic part of the quantum theory of how these forces work and how they scale with energy (and) how they scale with time in the universe.

Fraser: What in the universe depends on it; how would the universe be different if Alpha was different?

Newman: Because Alpha determines how strong the electromagnetic force is; that’s the force that holds atoms together; that’s the force that causes things to interact with light, so if the force (Alpha) had different strength, atoms wouldn’t hold together, as well or they might hold together too strongly to allow chemical interactions. As well, if light and atoms didn’t interact very well, it would be very hard to see for instance, as we do. It is essential to our life. Because it’s so fundamental, it has ramifications all over the place that you wouldn’t even expect that can have affects on almost every interaction an atom undergoes or how an atom is structured.

Fraser: Where did the prediction come from that Alpha should remain constant since the Big Bang? Why was this even open to speculation?

Newman: It was generally expected that it was a universal constant of the universe. There were predictions in fact, that it was not just a constant, but a very simple constant that would be an integer; whatever 136 or whatever 137. For a while it was thought to be the value; not a 137.1, but a 137 even. That turned out to be numerology; it didn’t hold true, but it’s a value that comes out of nowhere, but is a fundamental part of the standard model of particle physics and all the other standard values of particle physics are things like the mass of an electron, the very basic thing. We would expect that there would be numbers that would describe the universe as a whole and if they describe the universe as a whole, they should describe they should describe it at any time or any place. Only in the last 20 or so years, when there have been unification theories, that predict many extra dimensions; there are theories that also predict that the constants of the universe as we perceive them are influenced by the presence of these extra dimensions and over time or over space, the values of these constants could actually change because of the extra degrees of freedom provided by these dimensions. Dark energy theories today also can predict changes in Alpha over time.

Fraser: Now I had reported a week before your story had come out that some Australian researchers had found that Alpha had been changing which I guess was a pretty big announcement. Do you know what research they had done to determine that it had changed?

Newman: So they’re using ? again an astrophysical method; trying to look at observations of very distant objects, deep in the past; in the distant universe, and tried to use those observations to look at quantities that should depend on Alpha; in their case, they’re looking at the wavelengths of light that are absorbed by gasses between us and quasars that are very bright objects, very far away. They have a method that tried to use many different kinds of elements counterbalancing each other trying to get as much sensitivity to Alpha as possible, but because it’s a complicated method, it requires a lot of complicated calculations. It’s certainly a more complicated method than the one we’ve tried. We’ve tried to keep things simple. So there are actually some groups who have used the same method and some of them have found changes in Alpha and some of them have found no change in Alpha with the method the Australian group is using.

Fraser: What was the method that you had used?

Newman: We are looking, not at quasars, not at the very brightest objects, but rather at galaxies which are more abundant. So we can look at greater numbers of objects. And it turns out that we are looking at a particular simple set of measurements, set of wavelengths; transitions in atoms that we can use to measure Alpha. It depends in a very straightforward way on the value of Alpha over time, so by making a pretty simple measurement, we were able to set a constraint on how Alpha could evolve without having to worry about lots of atomic physics and nuclear physics, but just the simplest thing we can do. Alpha is called the Fine Structure Constant, and we were actually measuring the strength of a Fine Structure transition in oxygen atoms.

Fraser: How precise is the calculations that you’re coming up with?

Newman: The precision is mostly limited by the just the number of objects we have in the DEEPTWO Redshift Survey; the dataset we’ve used to do this. Now, out of 50,000 objects in the survey, we have about 500 we can use for this test. That gives us a precision of about a part in 30,000 on the value of Alpha.

Fraser: Because I recall the Australians, it (Alpha) had changed in 1 in 100,000 or something like that?

Newman: Yes, so we can’t yet rule out their measurement. It’s modestly discrepant at this point. No scientist would look at these values and say one rules out the other because their nominal precision is high. The question is could there be something systematically wrong with the measurement; could there be something that goes wrong with that technique? Given that different groups have gotten different values it’s likely that something is wrong with one of the groups or the other; either the group that defines a change in Alpha or the group that doesn’t. We can’t yet rule that out, but with a larger sample, using our simple method, we can make a determination.

Fraser: What would it take then for you to be able to come to a conclusive answer that both you; the changers and the static people come to an agreement?

Newman: I think that more data coming from us would certainly help because currently we are able to show that we are not limited by any sort of systematic error or systematic uncertainty in what we’re doing. We are limited just by random errors and random errors, you can make better if you have a larger sample. The other techniques, the other groups are also trying to get more data to reduce their errors and to try to do measurements of a couple of different types to see if they can get consistent answers, not just with this more complex version of the method of looking at quasars, but now they are taking a step back and trying to use a slightly simpler method of that as well. So, hopefully these will converge and try to come to a common answer once their data sets come in.

Fraser: Right. Let’s say that you are wrong and it (Alpha) has been changing over time, what could that mean for the future of the universe? If it keeps going.

Newman: So the changes that are found are relatively slow; even the groups that do find significant changes and the changes that are found would be expected to get slower and slower as time goes on. Most predictions are that if Alpha does change, that it’s mostly changing in the first seconds of the universe. It just gets slower and slower and slower after that. So a secondary effect in the end, if it’s very slowly changing, the stars will burn out before it changes enough to affect the chemistry and interactions of atoms.

Posted on by Fraser Cain

Penumbral Lunar Eclipse, April 24

Image credit: NASA
NASA is planning to send people back to the Moon. Target date: 2015 or so. Too bad they won’t be there this Sunday because, on April 24th, there’s going to be a solar eclipse, and you can only see it from the Moon.

On Earth, solar eclipses happen when the Moon covers the Sun. On the Moon, the roles are reversed. It’s Earth that covers the Sun. Such an eclipse is “a marvelous sight,” according to Apollo 12 astronaut Alan Bean, who saw one in 1969. He was flying home from the Moon along with crewmates Pete Conrad and Dick Gordon when their spaceship flew through Earth’s shadow. “Our home planet [eclipsed] our own star.”

No one will see the April 24th eclipse, but we can imagine what it would be like:

You’re standing on the Moon. It’s broad daylight, almost high noon. The Sun is creeping slowly across the sky. How slowly? A lunar day is about 29.5 Earth-days long. So the Sun moves 29.5 times slower than our Earth-sense tells us it should. At that leisurely pace, the Sun approaches a dark but faintly-glowing disk three times its own size.

The disk is Earth with its nightside facing the Moon. You can see moonlit clouds floating over Earth’s dark oceans and continents. You can also see a faintly glowing ring of light around the planet–that’s Earth’s atmosphere with sunlight trickling through it. A telescope would show you Earth’s city lights, too. Beautiful.

Then the eclipse begins.

Looking through dark-filtered glasses, you watch the Sun slip behind Earth. Earth’s atmosphere, lit from behind, glows red, then redder, a ring of fire the color of sunset, interrupted here and there by the tops of the highest clouds.

Ninety minutes later–patience is required!–only a little bit of the Sun remains poking out over the edge of the planet. Arranged just so, the pair remind you of a giant sparkling diamond ring.

The Sun never completely vanishes because this eclipse is partial, not total. During a total eclipse, Earth would hide the Sun completely, which has the odd effect of turning the Moon blood red. But that’s another story.

Partial eclipses, while not as eerie or dramatic as total eclipses, are still good. In fact, future space tourists will probably rocket to the Moon to see them. It’ll be an exclusive club, people who’ve witnessed Earth taking a bite out of the Sun. The membership in 2005 is only two: Alan Bean and Dick Gordon, the surviving crew of Apollo 12.

Stuck on Earth, what can you do? As a matter of fact, it is possible to observe this Sunday’s solar eclipse from Earth in a roundabout way:

During the eclipse, Earth’s shadow will fall across the Moon and we can see that happen. Our planet’s shadow has two parts, a dark inner core called the umbra and a pale outer fringe called the penumbra. (Aside: Step outside on a sunny day and look at your own shadow. It’s dark in the middle and pale-fuzzy around the edges. You have your own umbra and penumbra.) The Moon on April 24th will glide through Earth’s penumbra, producing what astronomers call a “penumbral lunar eclipse.”

Penumbral eclipses are not easy to see because the penumbra is so pale. If you’re enthusiastic about such things, however, it’s worth a look. A subtle but distinct shading should be visible across northern parts of the Moon during greatest eclipse around 09:55 UT on Sunday morning, April 24th. That’s 02:55 a.m. PDT or 05:55 a.m. EDT in North America. The best place to be is the Hawaiian Islands where the eclipse happens only 5 minutes before local midnight on Saturday, April 23rd. The Moon will be high in the sky, ideally placed.

Even in Hawaii the experience is subtle. Not impressed? You’re just on the wrong world.

Original Source: Science@NASA

Posted on by Fraser Cain

Solar Nebula Lasted 2 Million Years

Image credit: William K. Hartmann/PSI
The oxygen and magnesium content of some of the oldest objects in the universe are giving clues to the lifetime of the solar nebula, the mass of dust and gas that eventually led to the formation of our solar system.
Specimen from the Allende Meteorite

By looking at the content of chondrules and calcium aluminum-rich inclusions (CAIs), both components of the primitive meteorite Allende, Lab physicist Ian Hutcheon, with colleagues from the University of Hawaii at Manoa, the Tokyo Institute of Technology and the Smithsonian Institution, found that the age difference between the two fragments points directly to the lifetime of the solar nebula.

CAIs were formed in an oxygen-rich environment and date to 4.567 billion years old, while chondrules were formed in an oxygen setting much like that on Earth and date to 4.565 billion, or less, years old.

?Over this span of about two million years, the oxygen in the solar nebula changed substantially in its isotopic makeup,? Hutcheon said. ?This is telling us that oxygen was evolving fairly rapidly.?

The research appears in the April 21 edition of the journal Nature.

One of the signatures of CAIs is an enrichment of the isotope Oxygen 16 (O-16). An isotope is a variation of an element that is heavier or lighter than the standard form of the element because each atom has more or fewer neutrons in its nucleus. The CAIs in this study are enriched with an amount of O-16 4 percent more than that found on Earth. And, while 4 percent may not sound like much, this O-16 enrichment is an indelible signature of the oldest solar system objects, like CAIs. CAIs and chondrules are tens of millions of years older than more modern objects in the solar system, such as planets, which formed about 4.5 billion years ago.

?By the time chondrules formed, the O-16 content changed to resemble what we have on Earth today,? Hutcheon said.

In the past, the estimated lifetime of the solar nebula ranged from less than a million years to ten million years. However, through analysis of the mineral composition and oxygen and magnesium isotope content of CAIs and chondrules, the team was able to refine that lifespan to roughly two million years.

?In the past the age difference between CAIs and chondrules was not well-defined,? Hutcheon said. ?Refining the lifetime of the solar nebula is quite significant in terms of understanding how our solar system formed.?

Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy’s National Nuclear Security Administration.

Original Source: LLNL News Release

Posted on by Fraser Cain

Extreme Life in Yellowstone Gives More Hope for Life on Mars

University of Colorado at Boulder researchers say a bizarre group of microbes found living inside rocks in an inhospitable geothermal environment at Wyoming’s Yellowstone National Park could provide tantalizing clues about ancient life on Earth and help steer the hunt for evidence of life on Mars.

The CU-Boulder research team reported the microbes were discovered in the pores of rocks in a highly acidic environment with high concentrations of metals and silicates at roughly 95 degrees F in Yellowstone’s Norris Geyser Basin. The new study shows the microbe communities are subject to fossilization and have the potential to become preserved in the geologic record.

Scientists believe similar kinds of geothermal environments may once have existed on Mars, where astrobiologists have intensified the search for past and present life forms in recent years.

A paper by CU-Boulder doctoral student Jeffrey Walker, postdoctoral fellow John Spear and Professor Norman Pace of CU-Boulder’s molecular, cellular and developmental biology department and the Center for Astrobiology appears in the April 21 issue of Nature.

The research was funded by the National Science Foundation and NASA.

“This is the first description of these microbial communities, which may be a good diagnostic indicator of past life on Mars because of their potential for fossil preservation,” said Walker. “The prevalence of this type of microbial life in Yellowstone means that Martian rocks associated with former hydrothermal systems may be the best hope for finding evidence of past life there.”

Located about 20 miles northwest of Yellowstone Lake, Norris Geyser Basin is considered to be the hottest and most active geyser basin in Yellowstone and perhaps the world. It also is extremely acidic, according to the researchers.

“The pores in the rocks where these creatures live has a pH value of one, which dissolves nails,” said Pace. “This is another example that life can be robust in an environment most humans view as inhospitable.”

The process used to identify the organisms developed by Pace is much more sensitive than standard lab-culturing techniques that typically yield a small, biased fraction of organisms from any environment, said Walker. In this method, the researchers detected and identified organisms by reading gene sequences.

“Each kind of organism has a unique sequence, which is used to map its position in the tree of life,” said Walker. “It’s a family tree of sorts that describes the genetic relationship between all known organisms.”

Walker discovered the new microbe community in 2003 after breaking apart a chunk of sandstone-like rock in the Norris Geyser Basin. “I immediately noticed a distinctive green band just beneath the surface,” he said. “It was one of those ‘eureka’ moments.”

An analysis determined the green band was caused by a new species of photosynthetic microbes in the Cyanidium group, a kind of alga that is among the most acid-tolerant photosynthetic organisms known, said Walker. Cyanidium organisms made up about 26 percent of the microbes identified in the Norris Geyser Basin study by the CU-Boulder team, Walker said.

Surprisingly, the most abundant microbes identified by the team were a new species of Mycobacterium, a group of microbes best known for causing human illnesses like tuberculosis and leprosy, Walker said. Extremely rare and never before identified in such extreme hydrothermal environments, Mycobacterium made up 37 percent of the total number of microbes identified by the CU-Boulder team.

Pace described the new life form in the Norris Geyser Basin as “pretty weird.” “It may well be a new type of lichen-like symbiosis,” said Pace, who won a MacArthur Fellowship, or “genius grant,” in 2001. “It resembles a lichen, but instead of being comprised of a symbiosis between a fungus and an alga, it seems to be an association of the Mycobacterium with an alga.”

While photosynthesis appears to be a key energy source for most of the creatures, at least some Yellowstone microbes are believed to get energy from the dissolved metals and hydrogen found in the pore water of the rock, Walker said. A study by the CU-Boulder team published by the National Academy of Sciences in January 2005 indicated Yellowstone microbe populations living in hot springs at temperatures more than 158 degrees F use hydrogen as their primary fuel source.

The research effort in the Norris Geyser Basin shows that rock formation processes occurring in the hydrothermal environment under study make very real fossil imprints of the organisms embedded in the rock at various stages, showing how the distinctive fossils develop over time, according to the research team.

“Remnants of these communities could serve as ‘biosignatures’ and provide important clues about ancient life associated with geothermal environments on Earth or elsewhere in the Solar System,” the authors wrote in Nature.

Original Source: University of Colorado News Release

Posted on by Fraser Cain

Podcast: Alpha, Still Constant After All These Years

There’s a number in the Universe which we humans call alpha – or the fine structure constant. It shows up in almost every mathematical formula dealing with magnetism and electricity. The very speed of light depends on it. If the value for alpha was even a little bit different, the Universe as we know it wouldn’t exist – you, me and everyone on Earth wouldn’t be here. Some physicists have recently reported that the value for alpha has been slowly changing since the Big Bang. Others, including Jeffrey Newman from the Lawrence Berkeley National Laboratory have good evidence that alpha has remained unchanged for at least 7 billion years.
Continue reading “Podcast: Alpha, Still Constant After All These Years”

Posted on by Fraser Cain

Spitzer Sees an Alien Asteroid Belt

NASA’s Spitzer Space Telescope has spotted what may be the dusty spray of asteroids banging together in a belt that orbits a star like our Sun. The discovery offers astronomers a rare glimpse at a distant star system that resembles our home, and may represent a significant step toward learning if and where other Earths form.

“Asteroids are the leftover building blocks of rocky planets like Earth,” said Dr. Charles Beichman of the California Institute of Technology, Pasadena, Calif. Beichman is lead author of a paper that will appear in the Astrophysical Journal. “We can’t directly see other terrestrial planets, but now we can study their dusty fossils.”

Asteroid belts are the junkyards of planetary systems. They are littered with the rocky scraps of failed planets, which occasionally crash into each other, kicking up plumes of dust. In our own solar system, asteroids have collided with Earth, the moon and other planets.

If confirmed, the new asteroid belt would be the first detected around a star about the same age and size as our Sun. The star, called HD69830, is located 41 light-years away from Earth. There are two other known distant asteroid belts, but they circle younger, more massive stars.

While this new belt is the closest known match to our own, it is not a perfect twin. It is thicker than our asteroid belt, with 25 times as much material. If our solar system had a belt this dense, its dust would light up the night skies as a brilliant band.

The alien belt is also much closer to its star. Our asteroid belt lies between the orbits of Mars and Jupiter, whereas this one is located inside an orbit equivalent to that of Venus.

Yet, the two belts may have one important trait in common. In our solar system, Jupiter acts as an outer wall to the asteroid belt, shepherding its debris into a series of bands. Similarly, an unseen planet the size of Saturn or smaller may be marshalling this star’s rubble.

One of NASA’s future planet-hunting missions, SIM PlanetQuest, may ultimately identify such a planet orbiting HD 69830. The mission, which will detect planets as small as a few Earth masses, is scheduled to launch in 2011.

Beichman and colleagues used Spitzer’s infrared spectrograph to observe 85 Sun-like stars. Only HD 69830 was found to possibly host an asteroid belt. They did not see the asteroids themselves, but detected a thick disk of warm dust confined to the inner portion of the star system. The dust most likely came from an asteroid belt in which dusty smash-ups occur relatively frequently, about every 1,000 years.

“Because this belt has more asteroids than ours, collisions are larger and more frequent, which is why Spitzer could detect the belt,” said Dr. George Rieke, University of Arizona, Tucson, co-author of the paper. “Our present-day solar system is a quieter place, with impacts of the scale that killed the dinosaurs occurring only every 100 million years or so.”

To confirm that the dust detected by Spitzer is indeed ground-up asteroids, a second less-likely theory will have to be ruled out. According to the astronomers, it is possible a giant comet, almost as big as Pluto, got knocked into the inner solar system and is slowly boiling away, leaving a trail of dust. This hypothesis came about when the astronomers discovered the dust around the star consists of small silicate crystals like those found in comet Hale-Bopp. One of these crystals is the bright green-colored gem called forsterite.

“The ‘super comet’ theory is more of a long shot,” Beichman said, “but we’ll know soon enough.” Future observations of the star using Spitzer and ground-based telescopes are expected to conclude whether asteroids or comets are the source of the dust.

Other authors of this study include G. Bryden, T. Gautier, K. Stapelfeldt and M. Werner of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.; and K. Misselt, J. Stansberry and D. Trilling of the University of Arizona.

The Jet Propulsion Laboratory manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center, at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. Spitzer’s infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Dr. Jim Houck of Cornell.

For artist’s concepts and more information, visit: www.spitzer.caltech.edu/spitzer.

Original Source: Spitzer News Release

Posted on by Fraser Cain

Is There Water on the Moon?

The first object in the night sky most of us ever saw, the Moon remains a mystery. Haunted by poets, looked upon by youngsters in love, studied intensely by astronomers for four centuries, examined by geologists for the last 50 years, walked upon by twelve humans, this is Earth’s satellite.

And as we look towards the Moon with thoughts of setting up a permanent home there, one new question is paramount: does the Moon have water? Although none has been definitely detected, recent evidence suggests that it’s there.

Why should there be water on the Moon? Simply for the same reason that there’s water on Earth. A favorite theory is that water, either as water by itself or as its components of hydrogen and oxygen, was deposited on Earth during its early history–mostly during a period of “late heavy bombardment” 3.9 billion years ago–by the impacts of comets and asteroids. Because the Moon shares the same area of space as Earth, it should have received its share of water as well. However, since it has only a tiny fraction of Earth’s gravity, most of the Moon’s water supply should have evaporated and drifted off into space long ago. Most, but perhaps not all.

In ancient times, observers commonly thought the Moon had abundant water–in fact, the great lava plains like Mare Imbrium were called maria, or seas. But when Neil Armstrong and Buzz Aldrin landed on the Moon in 1969, they stepped out not into the water of the Sea of Tranquillity, but onto basaltic rock. No one was surprised by that–the idea of lunar maria had been replaced by lava plains decades earlier.

As preparations were underway in the mid 1960s for the Apollo program, questions about water on the Moon were barely on the radar screen. Geologists and astronomers were divided at the time as to whether the lunar surface was a result of volcanic forces from beneath, or cosmic forces from above. Grove Carl Gilbert in 1893 already had the answer. That famous geologist suggested that large asteroidal objects hit the Moon, forming its craters. Ralph Baldwin articulated the same idea in 1949, and Gene Shoemaker revived the idea again around 1960. Shoemaker, almost alone among geologists of his day, saw the Moon as a fertile subject for field geology. He saw the craters on the Moon as logical impact sites that were formed not gradually in eons, but explosively in seconds.

The Apollo flights confirmed that the dominant geological process on the Moon is impact-related. That discovery, in turn, ushered in a new question: Since Earth’s water was probably delivered largely by comets and asteroids, could this process have done the same for the Moon? And could some of that water still be there?

In 1994, the SDI-NASA Clementine spacecraft orbited the Moon and mapped its surface. In one experiment, Clementine beamed radio signals into shadowed craters near the Moon’s south pole. The reflections, received by antennas on Earth, seemed to come from icy material.

That makes sense. If there is water on the Moon, it’s probably hiding in the permanent shadows of deep, cold craters, safe from vaporizing sunlight, frozen solid.

So far so good, but… the Clementine data were not conclusive, and when astronomers tried to find ice in the same craters using the giant Arecibo radar in Puerto Rico, they couldn’t. Maybe Clementine was somehow wrong.

In 1998, NASA sent another spacecraft, Lunar Prospector, to check. Using a device called a neutron spectrometer, Lunar Prospector scanned the Moon’s surface for hydrogen-rich minerals. Once again, polar craters yielded an intriguing signal: neutron ratios indicated hydrogen. Could it be the “H” in H2O? Many researchers think so.

Lunar Prospector eventually sacrificed itself to the search. When the spacecraft’s primary mission was finished, NASA decided to crash Prospector near the Moon’s south pole, hoping to liberate a bit of its meager layer of water. Earth’s satellite might briefly become a comet as amounts of water vapor were released.

Lunar Prospector crashed, as planned, and several teams of researchers tried to detect that cloud, but without success. Either there was no water, or there was not enough water to be detected by Earth-based telescopes, or the telescopes were not looking in precisely the right place. In any event, no water was found from Prospector’s impact.

In 2008, NASA plans to send a new spacecraft to the Moon: the Lunar Reconnaissance Orbiter (LRO), bristling with advanced sensors that can sense water in at least four different ways. Scientists are hopeful that LRO can decide the question of Moon water once and for all.

Our interest is not just scientific. If we are indeed to build a base on the Moon, the presence of water already there would offer a tremendous advantage in building and running it. It’s been 35 years since we first set foot on the Moon. Now ambitious eyes once again look toward our satellite not just as a place to visit, but as a place to live.

Original Source: Science@NASA

Posted on by Fraser Cain

Perfect Liquid Hints at Early Universe

Physicists working to re-create the matter that existed at the birth of the universe expected something like a gas and ended up with the “perfect” liquid, four teams of researchers reported at an April 18 meeting of the American Physical Society. One of the teams is led by MIT.

“These truly stunning findings have led us to conclude that we are seeing something completely new–an unexpected form of matter–which is opening new avenues of thought about the fundamental properties of matter and the conditions that existed just after [the Big Bang],” said Raymond Orbach, director of the U.S. Department of Energy’s Office of Science, the primary supporter of the research.

Unlike ordinary liquids, in which individual molecules move about randomly, the new matter seems to move in a pattern that exhibits a high degree of coordination among the particles–something like a school of fish that responds as one entity while moving through a changing environment. That fluid motion is nearly “perfect,” as defined by the equations of hydrodynamics.

Picture a stream of honey, then a stream of water. “Water flows much more easily than honey, and the new liquid we’ve created seems to flow much more easily than water,” said Wit Busza, leader of the MIT team and the Francis Friedman Professor of Physics. Other MIT faculty involved in the work are Professor Bolek Wyslouch and Associate Professor Gunther Roland, both of physics.

Busza notes that the results don’t rule out that a gas-like form of matter existed at some point in the young universe, but the data do suggest “something different, and maybe even more interesting, at the lower energy densities created at RHIC (Relativistic Heavy Ion Collider).”

The research has also led to several other surprises. For example, “there is an elegance we see in the data that is not reflected in our theoretical understanding–yet,” said Roland.

Birth of the universe
About ten millionths of a second after the Big Bang, physicists believe that the universe was composed of a gas of weakly interacting objects, quarks and gluons that would ultimately clump together to form atomic nuclei and matter as we know it.

So, over the last 25 years, scientists have been working to re-create that gas, or quark-gluon plasma, by building ever-larger atom smashers. “The idea is to accelerate nuclei to nearly the speed of light, then have them crash head-on,” Busza said. “Under those conditions the plasma is expected to form.” The current results were achieved at the Relativistic Heavy Ion Collider located at the DOE’s Brookhaven National Laboratory.

RHIC accelerates gold nuclei in a circular tube some 2 kilometers in diameter. In four places the nuclei collide, and around those sites teams of scientists have built detectors to collect the data. The four instruments–STAR, PHENIX, PHOBOS and BRAHMS–vary in their approaches to tracking and analyzing particles’ behavior. The work reported at the APS meeting summarizes the first three years of RHIC results from all four devices. Papers from each team will also be published simultaneously in an upcoming issue of the journal Nuclear Physics A.

MIT is the lead institution for PHOBOS, a collaboration between the United States, Poland and Taiwan. “We are very small,” said Busza, who developed the concept for the device. “STAR and PHENIX each cost about $100 million and have some 400 staff. We cost less than $10 million and have about 50 people,” he said. (BRAHMS is also small.)

Nevertheless, the PHOBOS team got the first physics results from three of the five RHIC experimental runs and tied for first on a fourth. (The fifth run is still being analyzed.)

For one of those runs, the team collected the data, analyzed them and submitted a paper on the work all within five weeks. “That’s unheard of in high-energy physics,” said Busza, who credits Roland with the fast turnaround. “He was the person who managed the extraction of the physics from the data.”

What’s next?
Although the larger RHIC detectors will continue to collect data, PHOBOS has been retired. “From a cost-benefit perspective, we feel we’ve extracted as much knowledge as we can from such a small experiment,” Busza said.

So the team is now looking to the future. The members hope to continue their studies at RHIC’s successor, the Large Hadron Collider (LHC) being built in Europe. That facility will have 30 times the collision energy of RHIC, which will bring the scientists that much closer to the conditions at the birth of the universe. “At LHC we’ll test what we think we learned from RHIC,” Busza said. “We also expect new surprises, perhaps even bigger surprises,” he concluded.

MIT research staff currently involved in PHOBOS are Maarten Ballintijn, Piotr Kulinich, Christof Roland, George Stephans, Robin Verdier, Gerrit vanNieuwenhuizen and Constantin Loizides. Six graduate students are also on the team; the research has already resulted in five theses, with two on the way.

Original Source: MIT News Release