Posted on by Fraser Cain

Rovers are Getting a Little Dusty

Since landing on Mars a year ago, NASA’s pair of six-wheeled geologists have been constantly exposed to martian winds and dust. Because the rovers use solar power and sunlight is currently limited on Mars, the rovers can only cover from 50 to 100 feet on a good day. The sunlight is seasonal and also power-limiting as the rover’s age and get covered by dust. Among the failure models for eventually retiring the rovers, an electronic glitch or dust accumulation are most likely than a mechanical breakage.

Both rovers have been coated by some dust falling out of the atmosphere during that time, with estimates of the dust thickness ranging from 1 to 10 micrometers, or between 1/100th and 1/10th the width of a single human hair.

Of the two, NASA’s Mars Exploration Rover Spirit is definitely the more dust-laden. The Opportunity rover appears to be collecting less dust, perhaps because of a cleaning by wind or even “scavenging” of dust by frost that forms on the rover some nights during the martian winter. In imagining the texture of the rocks found by the Opportunity rover, the mission team has compared them to spongy sandstone. They are pockmarked, porous, dried and cracked. The voids and holes in these spongy rocks may have arisen from repeated cycles of evaporation to harden the surfaces followed by a washing away to dissolve the more soluble interior portions.

NASA’s Mars Exploration Rover Spirit is definitely the more dust-laden. As a result, Spirit has gradually experienced a decline in power as the thin layer of dust has accumulated on the solar panels, blocking some of the sunlight that is converted to electricity. The panoramic camera team’s analysis indicates that the layer of dust on Spirit’s calibration target is about 70 percent thicker than that on Opportunity’s.

Prior to this mission, the Meridiani plains were compared to the Rust Belt states, those in the middle north of America (Michigan, Ohio, Pennsylvania). The other comparison was to the red dirt found in Oklahoma and northern Texas–the so-called Red River region. In addition to red dirt, the rovers have found bedrock. On earth, bedrock is common in northern New England, particularly Maine and New Hampshire, the Granite state. But the wind blows around enough dry dust on Mars to cover what might be exposed bedrock. This debris layer blankets most of the rest of the planet. Additionally, meteors have pulverized the martian surface leaving a thick crushed layer.

A portion of Mars’ water vapor is moving from the north pole toward the south pole during the current northern-summer and southern-winter period. The transient increase in atmospheric water at Meridiani, just south of the equator, plus low temperatures near the surface, contribute to appearance of the clouds and frost. Frost shows up some mornings on the rover itself. The possibility that it has a clumping effect on the accumulated dust on solar panels is under consideration as a factor in unexpected boosts of electric output from the panels.

The atmosphere of Mars contains water, but in miniscule amounts. “Even though we are currently seeing frequent clouds with Opportunity, if you squeezed all of the water out of the atmosphere, it would only be less than 100 microns deep, about the thickness of a human hair,” said Mark Lemmon of Texas A&M University’s College of Geosciences.

Because of the lack of water, weather on Mars has a lot to do with dust in the atmosphere. A small dust storm one month before the rovers landed spread small amounts of dust around the planet.

“Both rovers saw very dusty skies at first. It was only after the dust settled after a few months that Spirit could see the rim of the crater it was in, Gusev Crater, about 40 miles away,” Lemmon said.

British scientists have speculated that the British Mars Lander, Beagle 2, crashed because the atmosphere was thinner than usual as a result of heating caused by atmospheric dust from the December storm.

“I can think of at least three things could kill us,” said Cornell’s principal investigator for the Mars rovers, Steve Squyres, when discussing the mission lifetime with the Astrobiology Magazine. “The first is dust build-up on the solar arrays. But the dust build-up is not that bad, especially for Opportunity, and with spring approaching both vehicles should do ok for awhile.”

“The second thing is if something mechanical goes wrong,” said Squyres. “The rovers have a lot of moving parts, and we’ve seen a few mechanical funnies on Spirit. Nothing serious, but enough to catch your attention. Stuff could just wear out.”

“The third thing is, we’ve got a lot of single-string electronics in these vehicles,” said Squyres. “There’s not a lot of redundancy. Now, we have the ultimate redundancy in that there are two vehicles. But within each rover there are a lot of electrical parts that, if they just flat-out fail on us, the rover’s dead. Bang! It just dies overnight and never talks to us again. That could happen.”

Original Source: NASA Astrobiology Magazine

Posted on by Fraser Cain

Missing Matter Could Be Clouds of Gas

NASA’s Chandra X-ray Observatory has discovered two huge intergalactic clouds of diffuse hot gas. These clouds are the best evidence yet that a vast cosmic web of hot gas contains the long-sought missing matter – about half of the atoms and ions in the Universe.

Various measurements give a good estimate of the mass-density of the baryons – the neutrons and protons that make up the nuclei of atoms and ions – in the Universe 10 billion years ago. However, sometime during the last 10 billion years a large fraction of the baryons, commonly referred to as “ordinary matter” to distinguish them from dark matter and dark energy, have gone missing.

“An inventory of all the baryons in stars and gas inside and outside of galaxies accounts for just over half the baryons that existed shortly after the Big Bang,” explained Fabrizio Nicastro of the Harvard-Smithsonian Center for Astrophysics, and lead author of a paper in the 3 February 2005 issue of Nature describing the recent research. “Now we have found the likely hiding place of the missing baryons.”

Nicastro and colleagues did not just stumble upon the missing baryons – they went looking for them. Computer simulations of the formation of galaxies and galaxy clusters indicated that the missing baryons might be contained in an extremely diffuse web-like system of gas clouds from which galaxies and clusters of galaxies formed.

These clouds have defied detection because of their predicted temperature range of a few hundred thousand to a million degrees Celsius, and their extremely low density. Evidence for this warm-hot intergalactic matter (WHIM) had been detected around our Galaxy, or in the Local Group of galaxies, but the lack of definitive evidence for WHIM outside our immediate cosmic neighborhood made any estimates of the universal mass-density of baryons unreliable.

The discovery of much more distant clouds came when the team took advantage of the historic X-ray brightening of the quasar-like galaxy Mkn 421 that began in October of 2002. Two Chandra observations of Mkn 421 in October 2002 and July 2003, yielded excellent quality X-ray spectral data. These data showed that two separate clouds of hot gas at distances from Earth of 150 million light years and 370 million light years were filtering out, or absorbing X-rays from Mkn 421.

The X-ray data show that ions of carbon, nitrogen, oxygen, and neon are present, and that the temperatures of the clouds are about 1 million degrees Celsius. Combining these data with observations at ultraviolet wavelengths enabled the team to estimate the thickness (about 2 million light years) and mass density of the clouds.

Assuming that the size and distribution of the clouds are representative, Nicastro and colleagues could make the first reliable estimate of average mass density of baryons in such clouds throughout the Universe. They found that it is consistent with the mass density of the missing baryons.

Mkn 421 was observed three times with Chandra’s Low-Energy Transmission Grating (LETG), twice in conjunction with the High Resolution Camera (May 2000 and July 2003) and once with the Advanced CCD Imaging Spectrometer (October 2002). The distance to Mkn 421 is 400 million light years.

NASA’s Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA’s Office of Space Science, Washington. Northrop Grumman of Redondo Beach, Calif., formerly TRW, Inc., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

Original Source: Chandra News Release

Posted on by Fraser Cain

Where Did the Modern Telescope Come From?

If you think about it, it was just a matter of time before the first telescope was invented. People have been fascinated by crystals for millenia. Many crystals – quartz for instance – are completely transparent. Others – rubies – absorb some frequencies of light and pass others. Shaping crystals into spheres can be done by cleaving, tumbling, and polishing – this removes sharp edges and rounds the surface. Dissecting a crystal begins with finding a flaw. Creating a half-sphere – or crystal segment – creates two different surfaces. Light is gathered by the convex frontface and projected toward a point of convergence by the planar backface. Because crystal segments have severe curves, the point of focus may be very close to the crystal itself. Due to short focal lengths, crystal segments make better microscopes than telescopes.

It wasn’t the crystal segment – but the lens of glass – that made modern telescopes possible. Convex lenses came out of glass ground in a way to correct far-sighted vision. Although both spectacles and crystal segments are convex, far-sighted lenses have less severe curves. Rays of light are only slightly bent from the parallel. Because of this, the point where the image takes form is much farther away from the lens. This creates image scale large enough for detailed human inspection.

The first use of lenses to augment sight can be traced back to the Middle East of the 11th century. An Arabian text (Opticae Thesaurus written by scientist-mathematician Al-hazen) notes that segments of crystal balls could be used to magnify small objects. In the late 13th century, an English monk (possibly referencing Roger Bacon’s Perspectiva of 1267) is said to have created the first practical near-focus spectacles to aid in reading the Bible. It wasn’t until 1440 when Nicholas of Cusa ground the first lens to correct near-sightedness -1. And it would be another four centuries before defects in lens shape itself (astigmatism) would be aided by a set of spectacles. (This was accomplished by the British astronomer George Airy in 1827 some 220 years after another – more famous astronomer – Johann Kepler first accurately described the effect of lenses on light.)

The earliest telescopes took form just after spectacle grinding became well-established as a means to correct both myopia and presbyopia. Because far-sighted lenses are convex, they make good “collectors” of light. A convex lens takes parallel beams from the distance and bends them to a common point of focus. This creates a virtual image in space – one that can be inspected more closely using a second lens. The virtue of a collecting lens is twofold: It combines light together (increasing its intensity) – and amplifies image scale – both to a degree potentially far greater than the eye alone is capable of.

Concave lenses (used to correct near-sightedness) splay light outward and make things appear smaller to the eye. A concave lens can increase the focal length of the eye whenever the eye’s own system (fixed cornea and morphing lens) falls short of focusing an image on the retina. Concave lenses make good eyepieces because they enable the eye to more closely inspect the virtual image cast by a convex lens. This is possible because convergent rays from a collecting lens are refracted toward the parallel by a concave lens. The effect is to show a nearby virtual image as though at a great distance. A single concave lens allows the eye lens to relax as if focused on infinity.

Combining convex and concave lenses was just a matter of time. We can imagine the very first occasion occurring as children toyed with the lens-grinder’s toil of the day – or possibly when the optician felt called to inspect one lens using another. Such an experience must have seemed almost magical: A distant tower instantly looms as if approached at the end of a long stroll; unrecognizable figures are suddenly seen to be close friends; natural boundaries – such as canals or rivers – are leapt over as though Mercury’s own wings were attached to the heals…

Once the telescope came to be, two new optical problems presented themselves. Light collecting lenses create curved virtual images. That curve is slightly “bowl-shaped” with the bottom turned toward the observer. This of course is just the opposite of how the eye itself sees the world. For the eye sees things as though arrayed on a great sphere whose center lies on the retina. So something had to be done to draw perimeter rays back toward the eye. This problem was partially resolved by astronomer Christiaan Huygens in the 1650’s. He did this by combining several lenses together as a unit. The use of two lenses brought more of the peripheral rays from a collecting lens toward the parallel. Huygen’s new eyepiece effectively flattened the image and allowed the eye to achieve focus across a wider field of view. But that field would still induce claustrophobia in most observers of today!

The final problem was more intractable – refracting lenses bend light based on wavelength or frequency. The greater the frequency, the more a particular color of light is bent. For this reason, objects displaying light of various colors (polychromatic light) are not seen at the same point of focus across the electro-magnetic spectrum. Basically lenses act in ways similar to prisms – creating a spread of colors, each with its own unique focal point.

Galileo’s first telescope only solved the problem of getting an eye close enough to magnify the virtual image. His instrument was composed of two lenses separable by a controlled distance to set focus. The objective lens had a less severe curve to collect light and bring it to various points of focus depending on color-frequency. The smaller lens – possessed of a more severe curve of shorter focal length – allowed Galileo’s observing eye to get close enough to the image to see magnified detail.

But Galileo’s scope could only be brought to focus near the middle of the eyepiece field of view. And focus could only be set based on the dominant color emitted or reflected by whatever Galileo was viewing at the time. Galileo usually observed bright studies – like the Moon, Venus, and Jupiter – using an aperture stop and took some pride in having come up with the idea!

Christiaan Huygens created the first – Huygenian – eyepiece after the time of Galileo. This eyepiece consists of two plano-convex lenses facing the collecting lens – not a single concave lens. The focal plane of the two lenses lies between the objective and eye lens elements. The use of two lenses flattened the curve of the image – but only over a score or so degrees of apparent field of view. Since Huygen’s time, eyepieces have become much more sophisticated. Beginning with this original concept of multiplicity, today’s eyepieces can add another half-dozen or so optical elements rearranged in both shape and position. Amateur astronomers can now purchase eyepieces off the shelf giving reasonably flat fields exceeding 80 degrees in apparent diameter-2.

The third problem – that of chromatically tinged multi-color images – was not solved in telescopy until a working reflector telescope was designed and constructed by Sir Isaac Newton in the 1670’s. That telescope eliminated the collecting lens altogether – though it still required the use of a refractory eyepiece (which contributes far less to “false color” than the objective does).

Meanwhile early attempts to fix the refractor were to simply make them longer. Scopes to 140 feet in length were devised. None had especially exorbitant lens diameters. Such spindly dynasaurs required a truly adventurous observer to use – but did “tone down” the color problem.

Despite eliminating color error, early reflectors had problems too. Newton’s scope used a spherically ground speculum mirror. Compared to the aluminum coating of modern reflector mirrors, speculum is a weak performer. At roughly three-quarters the light gathering ability of aluminum, speculum loses about one magnitude in light grasp. Thus the six-inch instrument devised by Newton behaved more like a contemporary 4 inch model. But this is not what made Newton’s instrument hard to sell, it simply provided very poor image quality. And this was due to the use of that spherically ground primary mirror.

Newton’s mirror did not bring all rays of light to common focus. The fault didn’t lay with the speculum – it lay with the shape of the mirror which – if extended 360 degrees – would make a complete circle. Such a mirror is incapable of bringing central light beams to the same point of focus as those nearer the rim. It wasn’t until 1740 when Scotland’s John Short corrected this problem (for on-axis light) by parabolizing the mirror. Short accomplished this in a very practical manner: Since parallel rays nearer the center of a spherical mirror overshoot marginal rays, why not just deepen the center and rein them in?

It wasn’t until the 1850’s that silver replaced speculum as the mirror surface of choice. Of course the more than 1000 parabolic reflectors fabricated by John Short all had speculum mirrors. And silver, like speculum, loses reflectivity rather quickly over time to oxidation. By 1930, the first professional telescopes were being coated with more durable and reflective aluminum. Despite this improvement, small reflectors bring less light to focus than refractors of comparable aperture.

Meanwhile, refractors evolved too. During John Short’s time, opticians figured out something Newton had not – how to get red and green light to merge at a common point of focus by refraction. This was first accomplished by Chester Moor Hall in 1725 and rediscovered a quarter century later by John Dolland. Hall and Dolland combined two different lenses – one convex and other concave. Each consisted of a different glass type (crown and flint) refracting light differently (based on refractive indices). The convex lens of crown glass did the immediate task of collecting light of all colors. This bent photons inward. The negative lens splayed the converging beam slightly outward. Where the positive lens caused red light to overshoot focus, the negative lens caused red to undershoot. Red and green blended and the eye saw yellow. The result was the achromatic refractor telescope – a type favored by many amateur astronomers today for inexpensive, small aperture, wide-field, but – in shorter focal ratios – less than ideal image quality use.

It wasn’t until the mid-nineteenth century that opticians managed to get blue-violet to join red and green at focus. That development initially came out of the use of exotic materials (flourite) as an element in the doublet objectives of high-powered optical microscopes – not telescopes. Three element telescope designs using standard glass types – triplets – solved the problem as well some forty years later (just before the twentieth-century).

Today’s amateur astronomers can choose from a wide assortment of scope types and manufacturers. There is no one scope for all skies, eyes, and celestial studies. Issues of field flatness (particularly with fast Newtonian telescopes), and hefty optical tubes (associated with large refractors) have been addressed by new optical configurations developed in the 1930’s. Instrument types – such as the SCT (Schmidt-Cassegrain telescope) and MCT (Maksutov-Cassegrain telescope) plus newton-esque Schmidt and Maksutov variants and oblique reflectors – are now manufactured in the USA and throughout the world. Each scope type developed to address some valid concern or another related to scope size, bulk, field flatness, image quality, contrast, cost, and portability.

Meanwhile refractors have taken center stage among optophiles – folks wanting the highest possible image quality irrespective of other constraints. Fully apochromatic (color-corrected) refractors provide some of the most stunning images available for optical, photographic, and CCD imaging use. But alas, such models are limited to smaller apertures due to significantly higher costs of materials (exotic low-dispersion crystals & glass), manufacture (up to six optical surfaces must be shaped) and greater load bearing requirements (due to heavy disks of glass).

All of today’s variety in scope types began with the discovery that two lenses of unequal curvature could be held up to the eye to transport human perception over great distances. Like many great technological advances, the modern astronomical telescope emerged out of three fundamental ingredients: Necessity, imagination, and a growing understanding of the way energy and matter interact.

So where did the modern astronomical telescope come from? Certainly the telescope went through a long period of constant improvement. But perhaps, just perhaps, the telescope is at essence a gift of the Universe itself exulting in profound admiration through human eyes, hearts, and minds…

-1 Questions exist as to who first created spectacles correcting far- and near-sighted vsion. It is unlikely that Abu Ali al-Hasan Ibn al-Haitham or Roger Bacon ever used a lens in this way. Confusing the issue of provenance is the question of how spectacles were actually worn. It is likely that the first visual aid was simply held to the eye as a monocle – necessity taking over from there. But would such a primitive method be historically recounted as “the origin of the spectacle”?

-2 The ability of a particular eyepiece to compensate for a necessarily curved virtual image is limited fundamentally by effective focal ratio and scope archetecture. Thus telescopes whose focal length are many times their aperture present less of an instantaneous curve at the “image plane”. Meanwhile scopes that refract light initially (catadioptics as well as refractors) have the advantage of better handling off-axis light. Both factors increase the radius of curvature of the projected image and simplify the eyepiece’s task of presenting a flat field to the eye.

About The Author:
Inspired by the early 1900’s masterpiece: “The Sky Through Three, Four, and Five Inch Telescopes”, Jeff Barbour got a start in astronomy and space science at the age of seven. Currently Jeff devotes much of his time observing the heavens and maintaining the website Astro.Geekjoy.

Posted on by Fraser Cain

Swift is Now Fully Operational

The Swift satellite’s Ultraviolet/Optical Telescope (UVOT) has seen first light, capturing an image of the Pinwheel Galaxy, long loved by amateur astronomers as the “perfect” face-on spiral galaxy. The UVOT now remains poised to observe its first gamma-ray burst and the Swift observatory, launched into Earth orbit in November 2004, is now fully operational.

Swift is a NASA-led mission dedicated to the gamma-ray burst mystery. These random and fleeting explosions likely signal the birth of black holes. With the UVOT turned on, Swift now is fully operational. Swift’s two other instruments — the Burst Alert Telescope (BAT) and the X-ray Telescope (XRT) — were turned on over the past several weeks and have been snapping up gamma-ray bursts ever since.

“After many years of effort building the UVOT, it was exciting to point it toward the famous Pinwheel Galaxy, M101,” said Peter Roming, UVOT Lead Scientist at Penn State. “The ultraviolet wavelengths in particular reveal regions of star formation in the galaxy’s wispy spiral arms. But more than a pretty image, this first-light observation is a test of the UVOT’s capabilities.”

Swift’s three telescopes work in unison. The BAT detects gamma-ray bursts and autonomously turns the satellite in seconds to bring the burst within view of the XRT and the UVOT, which provide detailed follow-up observations of the burst afterglow. Although the burst itself is gone within seconds, scientists can study the afterglow for clues about the origin and nature of the burst, much like detectives at a crime scene.

The UVOT serves several important functions. First, it will pinpoint the gamma-ray burst location a few minutes after the BAT detection. The XRT provides a burst position within a 1- to-2-arcsecond range. The UVOT will provide sub-arcsecond precision, a spot on the sky far smaller than the eye of a needle at arm’s length. This information is then relayed to scientists at observatories around the world so that they can view the afterglow with other telescopes.

As the name applies, the UVOT captures the optical and ultraviolet component of the fading burst afterglow. “The ‘big gun’ optical observatories such as Hubble, Keck, and VLT have provided useful data over the years, but only for the later portion of the afterglow,” said Keith Mason, the U.K. UVOT Lead at University College London?s Mullard Space Science Laboratory. “The UVOT isn’t as powerful as these observatories, but has the advantage of observing from the very dark skies of space. Moreover, it will start observing the burst afterglow within minutes, as opposed to the day-long or week-long lag times inherent with heavily used observatories. The bulk of the afterglow fades within hours.”

The ultraviolet portion will be particularly revealing, said Roming. “We know nearly nothing about the ultraviolet part of a gamma-ray burst afterglow,” he said. “This is because the atmosphere blocks most ultraviolet rays from reaching telescopes on Earth, and there have been few ultraviolet telescopes in orbit. We simply haven’t yet reached a burst fast enough with a UV telescope.”

The UVOT’s imaging capability will enable scientists to understand the shape of the afterglow as it evolves and fades. The telescope’s spectral capability will enable detailed analysis of the dynamics of the afterglow, such as the temperature, velocity, and direction of material ejected in the explosion.

The UVOT also will help scientists determine the distance to the closer gamma-ray bursts, within a redshift of 4, which corresponds to a distance of about 11 billion light years. The XRT will determine distances to more distant bursts.

Scientists hope to use the UVOT and XRT to observe the afterglow of short bursts, less than two seconds long. Such afterglows have not yet been seen; it is not clear if they fade fast or simply don’t exist. Some scientists think there are at least two kinds of gamma-ray bursts: longer ones (more than two seconds) that generate afterglows and that seem to be caused by massive star explosions, and shorter ones that may be caused by mergers of black holes or neutron stars. The UVOT and XRT will help to rule out various theories and scenarios.

The UVOT is a 30-centimeter telescope with intensified CCD detectors and is similar to an instrument on the European Space Agency’s XMM-Newton mission. The UVOT is as sensitive as a four-meter optical ground-based telescope. The UVOT’s day-to-day observations, however, will look nothing like M101. Distant and faint gamma-ray burst afterglows will appear as tiny smudges of light even to the powerful UVOT. The UVOT is a joint product of Penn State and the Mullard Space Science Laboratory.

Swift is a medium-class explorer mission managed by NASA Goddard. Swift is a NASA mission with participation of the Italian Space Agency and the Particle Physics and Astronomy Research Council in the United Kingdom. It was built in collaboration with national laboratories, universities and international partners, including Penn State University in Pennsylvania, U.S.A.; Los Alamos National Laboratory in New Mexico, U.S.A.; Sonoma State University in California, U.S.A.; the University of Leicester in Leicester, England; the Mullard Space Science Laboratory in Dorking, England; the Brera Observatory of the University of Milan in Italy; and the ASI Science Data Center in Rome, Italy.

Original Source: Eberly College of Science News Release

Posted on by Fraser Cain

Digging on Mars Won’t Be Easy

Imagine this scenario. The year is 2030 or thereabouts. After voyaging six months from Earth, you and several other astronauts are the first humans on Mars. You’re standing on an alien world, dusty red dirt beneath your feet, looking around at a bunch of mining equipment deposited by previous robotic landers.

Echoing in your ears are the final words from mission control: “Your mission, should you care to accept it, is to return to Earth–if possible using fuel and oxygen you mine from the sands of Mars. Good luck!”

It sounds simple enough, mining raw materials from a rocky, sandy planet. We do it here on Earth, why not on Mars, too? But it’s not as simple as it sounds. Nothing about granular physics ever is.

Granular physics is the science of grains, everything from kernels of corn to grains of sand to grounds of coffee. These are common everyday substances, but they can be vexingly difficult to predict. One moment they behave like solids, the next like liquids. Consider a dump truck full of gravel. When the truck begins to tilt, the gravel remains in a solid pile, until at a certain angle it suddenly becomes a thundering river of rock.

Understanding granular physics is essential for designing industrial machinery to handle vast quantities of small solids–like fine Martian sand.

The problem is, even here on Earth “industrial plants don’t work very well because we don’t understand equations for granular materials as well as we understand the equations for liquids and gases,” says James T. Jenkins, professor of theoretical and applied mechanics at Cornell University in Ithaca, N.Y. “That’s why coal-fired power plants operate at low efficiencies and have higher failure rates compared to liquid-fuel or gas-fired power plants.”

So “do we understand granular processing well enough to do it on Mars?” he asks.

Let’s start with excavation: “If you dig a trench on Mars, how steep can the sides be and remain stable without caving in?” wonders Stein Sture, professor of civil, environmental, and architectural engineering and associate dean at the University of Colorado in Boulder. There’s no definite answer, not yet. The layering of dusty soils and rock on Mars isn’t well enough known.

Some information about the mechanical composition of the top meter or so of Martian soils could be gained by ground-penetrating radar or other sounding devices, Sture points out, but much deeper and you “probably need to take core samples.” NASA’s Phoenix Mars lander (landing 2008) will be able to dig trenches about a half-meter deep; the 2009 Mars Science Laboratory will be able to cut out rock cores. Both missions will provide valuable new data.

To go even deeper, Sture (in connection with the University of Colorado’s Center for Space Construction) is developing innovative diggers whose business ends vibrate into soils. Agitation helps break cohesive bonds holding compacted soils together and can also help mitigate the risk of soils collapsing. Machines like these might one day go to Mars, too.

Another problem is “hoppers”–the funnels miners use to guide sand and gravel onto conveyor belts for processing. Knowledge of Martian soils would be vital in designing the most efficient and maintenance-free hoppers. “We don’t understand why hoppers jam,” Jenkins says. Jams are so frequent, in fact, that “on Earth, every hopper has a hammer close by.” Banging on the hopper frees the jam. On Mars, where there would be only a few people around to tend equipment, you’d want hoppers to work better than that. Jenkins and colleagues are researching why granular flows jam.

And then there’s transportation: The Mars rovers Spirit and Opportunity have had little trouble driving miles around their landing sites since 2004. But these rovers are only about the size of an average office desk and only about as massive as an adult. They’re go-carts compared to the massive vehicles possibly needed for transporting tons of Martian sand and rock. Bigger vehicles are going to have a tougher time getting around.

Sture explains: As early as the 1960s when scientists were first studying possible solar-powered rovers for negotiating loose sands on the Moon and other planets, they calculated “that the maximum viable continuous pressure for rolling contact pressure over Martian soils is only 0.2 pounds per square inch (psi),” especially when traveling up or down slopes. This low figure has been confirmed by the behavior of Spirit and Opportunity.

A rolling contact pressure of only 0.2 psi “means that a vehicle has to be light-weight or has to have a way of effectively distributing the load to many wheels or tracks. Reducing contact pressure is crucial so the wheels don’t dig into soft soil or break through duricrusts [thin sheets of cemented soils, like the thin crust on windblown snow on Earth] and get stuck.”

That requirement implies that a vehicle for moving heavier loads–people, habitats, equipment–might be “a huge Fellini-type thing with wheels 4 to 6 meters (12 to 18 feet) in diameter,” says Sture, referring to the famous Italian director of surreal films. Or it might have enormous open-mesh metal treads like a cross between highway-construction backhoes on Earth and the lunar rover used during the Apollo program on the Moon. Thus, tracked or belted vehicles seem promising for carrying large payloads.

A final challenge facing granular physicists is to figure out how to keep equipment operating through Mars’ seasonal dust storms. Martian storms whip fine dust through the air at velocities of 50 m/s (100+ mph), scouring every exposed surface, sifting into every crevice, burying exposed structures both natural and manmade, and reducing visibility to meters or less. Jenkins and other investigators are studying the physics of aeolian [wind] transporting of sand and dust on Earth, both to understand the formation and moving of dunes on Mars, and also to ascertain what sites for eventual habitats might be best protected from prevailing winds (for example, in the lee of large rocks).

Returning to Jenkins’s big question, “do we understand granular processing well enough to do it on Mars?” The unsettling answer is: we don’t yet know.

Working with imperfect knowledge is okay on Earth because, usually, no one suffers much from that ignorance. But on Mars, ignorance could mean reduced efficiency or worse preventing the astronauts from mining enough oxygen and hydrogen to breathe or use for fuel to return to Earth.

Granular physicists analyzing data from the Mars rovers, building new digging machines, tinkering with equations, are doing their level best to find the answers. It’s all part of NASA’s strategy to learn how to get to Mars … and back again.

Original Source: Science@NASA

Posted on by Fraser Cain

Interview Asteroid Researcher Dr. David J. Tholen

With all the recent news about asteroids and comets, I figure you’ve got a lot of questions. Well, now’s your chance to get some answers. We’ve lined up astronomer Dr. David J. Tholen, a professor at the University of Hawaii, Institute for Astronomy who specializes in the search for Earth-crossing asteroids. Once again, visit the forum, post your questions for David, and we’ll pick through and send him some zingers. I’ll publish his answers in an upcoming issue of Universe Today.

Click here to visit the forum and post your question.

Thanks!

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

What’s Up This Week – Jan 31 – Feb 6, 2005

Image credit: Emmanuel Mallart
Monday, January 31 – So, where is Comet Machholz and what has it been doing while the Moon was out? Heading north! As we’ve watched its rapid progress (a degree a day at times!) since it first appeared in the south, you will now find Machholz tonight just southeast of Eta Cassiopeia. Having made its closest approach to the Sun and heading for the outer limits, C/2004 Q2 will soon start to shrink and fade, but it’s still a prime time player! Catch it tonight…

As we relaxed and viewed the “Great Orion Nebula” last week, I am sure that many of you realize this is a highly complex region of sky that deserves much more attention to detail. With the Moon satisfactorily out of the way during the early evening hours, let’s take the time to do a much more serious study over the next few evenings.

Tonight our goal is Iota Orionis. Known to the Arabs as “the Bright One of the Sword”, we know it as the southern-most star in its asterism’s namesake. Iota is estimated to be around 2000 light years away and is about 20,000 times brighter than our own Sol, but in the telescope you will find Iota to be an easy and charming triple star. The bluish B star is relatively close at 11″ in separation, but a bright 6.9 in magnitude. Much more distant at 50″ is the reddish C star, and far more disparate at magnitude 11. Iota itself is a spectroscopic binary and you will note another “white” double (Struve 747) unrelated to Iota about 8′ to the southwest.

Staying at high power, the reason I ask you to look here tonight is not to conquer a Herschel 400 object, but to study a region of the sky that would be far more impressive if it weren’t for its alluring neighbor. If you look closely, you will see that Iota is involved in a great region of emission nebula known as the NGC 1900 along with a small open cluster known as H 31. To be sure, the area is vague, as are all low surface brightness nebulae, but do look to the east of Iota where a much brighter, roundish area makes an unmistakable appearance!

Tuesday, February 1 – If you are up early this morning, today is the best time to catch lunar feature – Rupes Recta. The angle of the lighting will be just perfect to highlight this 110 km long feature!

Please take a moment to remember Columbia – the first Space Shuttle to travel to Earth orbit – and its brave crew who left us two years ago today. Rick D. Husband, William C. McCool, Michael P. Anderson, David M. Brown, Kalpana Chawla, Laurel Blair Salton Clark, and Ilan Ramon… We wish you godspeed.

Tonight let’s head for the “holy grail” of multiple star systems as we look into the fueling core of the M42 – Theta Orionis. Are you ready to walk into “the Trap”? Even the smallest of telescopes can reveal the four bright stars that comprise the quadrangle at the heart of the Great Orion Nebula known as the “Trapezium”. Both the beginner and the seasoned veteran know that there are actually eight stars in this region and the journey we are about to undertake requires both aperture and fine skies. But what can you really see?

All four primary stars are easy. A steady hand with binoculars and even the most modest of telescopes make this foursome an awesome sight… And they seem to be in a dark “notch” of their own, don’t they? A telescope of 150mm in aperture will reveal two additional 11th magnitude stars, but excellent skies could mean the even smaller aperture could detect them. They will appear as “red” companions to the “blue/white” primary stars. But what of the other two? The remaining two components average about magnitude 16, putting them within reach of large amateur scopes, but what would you see?

When I first began observing the Trapezium area with a 12.5″ telescope, I was sure that I would never see the two faintest members of the group. I was new to challenging double stars and had never looked at a diagram. (To this day, I still prefer to observe and describe things first and confirm them later. Knowing in advance what you are “supposed” to see colours what you “can” see.) I had seen the fainter stars that appeared as doubles, along with a faint wink here and there as well as one to the outside that made the whole thing appear like a pentagon. Little did I realize I was perceiving all eight members, and there seemed to be so much more just on the edge of my perception. Thus began my own personal quest to study the “Trapezium” on a more professional level, just like challenging galaxy studies.

Using the 31″ reflector at Warren Rupp Observatory, it was time to “walk into the Trap” and to answer all my observing questions through visual confirmation. While at first glance with a small telescope, the background region in this area might appear a black void – it is not. The nebula continues here, but changes form. Instead of seeing “smoke-like” filaments, the region around the Trapezium is scalloped, like fish scales. You can never see this in a photograph! I realized immediately that both the G and H stars that I had always questioned were quite within range of my 12.5″ as I recognized the pattern. Then a moment of perfect clarity came and the view literally exploded in dozens of stars buried within the field surrounding these eight known as the “Trapezium”.

Upon formal study, I found that there are around 300 such stars within 5′ of the Theta Orionis complex that exceed magnitude 17. According to Strand, the expansion rate puts them at an approximate age of 30,000 years, making it the youngest star cluster known. Regardless of what size telescope you use, you owe it to yourself to take the time to power up on the “Trap”. Since the time the area was revealed to my eyes in all its open glory, I have seen scallops in the nebula and both fainter members on nights with exceptional seeing in much smaller telescopes. No matter how many stars you are able to resolve out of this region, you are looking into the very beginnings of starbirth… A womb with a view!

Wednesday, February 2 – Do you get up for work before dawn? Take a moment to step outside and have a look at Jupiter. Our solar system’s largest planet will go stationary (retro) in its orbit during the early morning hours. You’ll find it within 3 degrees of Spica!

Tonight our study region is to the northeast of the Great Orion Nebula (M42) and has a designation of its own – M43. Discovered by De Mairan in the latter half of the 18th century, this emission nebula appears to be separate from the M42, but the division known as “the Fish Mouth” is actually caused by dark gas and dust within the nebula itself. At the heart of it is 7th magnitude “Bond’s Star” – and wouldn’t 007 be proud? This unusually bright OB star is creating a matter-bound Stromgren sphere!

Translated loosely, this star is actually ionizing the gas near it, making a orb shaped area of glowing hydrogen gas. Its size is governed by the density of both the gas and dust that surround “Bond’s Star”. This “exciting” star of our show is more properly known as Nu Orionis and near it lies a dense concentration of neutral material known as the “Orion Ridge”. It is this combination of dust – mixed with gases – that make for a well balanced area of star formation!

And besides… It’s just cool. 😉

Thursday, February 3 – This morning at 14:00 UT, the Moon will have reached maximum libration, turning Crater Otto Struve our way. And speaking of the Moon, on this day in 1966, the first soft landing on the lunar surface was achieved by Soviet Luna 9. Spaseba!

Lace up your Nikes and let’s head out tonight above The Great Orion Nebula and find “The Running Man”…

Located just a half a degree north of the M43, this tripartite nebula consists of three separate areas of emission and reflection nebulae that seem to be visually connected. The NGC 1977, NGC 1975 and NGC1973 would probably be pretty spectacular if they were a bit more distant from their grand neighbor! This whispery soft, conjoining nebula’s fueling source is multiple star 42 Orionis. To the eye, a lovely “triangle” of bright nebula with several enshrouded stars make a wonderfully large region for exploration. Can you see the “Running Man” within?

Friday, February 4 – Wake up, Europe! This morning the crescent Moon will occult Antares for a substantial portion of viewers. Please check IOTA tables for viewing areas and times. Klare nacht!

For those of us not so fortunate, we can always look about 8 degrees north of Mars this morning for Pluto as we note its discoverer – Clyde Tombaugh – born on this day in 1906.

Let’s return again to Orion tonight, but preferably with binoculars since we will be studying a very large region known as “Barnard’s Loop”. Extending in a massive area about the size of the “bow”, you will find Barnard’s photographic namesake to the eastern edge of Orion, where it extends almost half the size of the constellation between Alpha and Kappa.

Because the Orion complex contains so many rapidly evolving stars, it stands to reason that a supernova should have occurred at some time. “Barnard’s Loop” is quite probably the shell leftover from such a cataclysmic event. If taken as a “whole”, it would encompass 10 degrees of sky!

For the most past, the nebula itself is very vague, but the eastern arc (where we are observing tonight) is relatively well defined against the starry field. Although it is similar to the Cygus Loop (“Veil Nebula”), our Barnard Loop is far more ancient. If you have transparent, dark skies? Enjoy! You can trace several degrees of this ancient remnant using just binoculars.

Saturday, February 5 – On this day in 1963, the first quasar redshift was measured by Maarten Schmidt and in 1974 Mariner 10 captured the first close-up photos of Venus.

Tonight I ask you to once again take out your telescopes and explore a region with me that we have previously visited – the M78. It is for the very sake of amateur astronomy that I ask you to do this… And here is why!

On January 23, 2004 a young backyard astronomer named Jay McNeil was checking out his new 3″ telescope by taking some long exposures of the M78. Little did Jay know at the time, but he was about to make a huge discovery! When he later developed his photographs, there was a nebulous patch there that had no designation. When he reported his findings to the professionals, they confirmed it had no official designation and that Jay had stumbled onto something quite unique! It is believed that Jay’s discovery was a variable accretion disc around newborn star – IRAS 05436-0007. Little is known about the region, but it seems that it had been caught in a photo once in the past but never studied. Even the Digital Sky Surveys had no record of it!

Although Jay’s discovery might not be bright enough tonight to be seen just south of the M78, it is a variable and circumstance plays a big role in any observation. Before you think that being a backyard astronomer has no real importance to science — remember a teenager in a Kentucky backyard with a 3″ telescope…

Catching what professionals had missed!

Sunday, February 6 – Do you need a smile? Then look at the waning crescent Moon this morning. On this day in 1971, Apollo 14 astronaut Alan Shepherd was the first human to “tee off” from the lunar surface! I wonder if that golf ball is still orbiting?!

Tonight let’s return again to Orion’s “Belt” and bright eastern star Zeta. Having visited this before, we know Alnitak is a delightful triple as well as home to the incredible “Flame” and “Horsehead” nebula. Heading next to the western-most of the trio, we find Delta – or Mintaka. Even small telescopes will be delighted to find that Mintaka is also a double with its 6.7 magnitude “blue” companion at an easy separation of 53″ north of the primary.

But you knew I was saving the best for last, didn’t you?

Now let’s go for the center-most star and identify Epsilon. Known to the Arabs as Alnilam, or the “Belt of Pearls”, Epsilon is a super-giant star that resides about 1600 light years away from us. For those with average telescopes, you will notice a “haze” around Alnilam and you would be correct. It is also surrounded by a reflection nebula
NGC1990 – a circular gaseous region that spans around 20 light years, fueled by Epsilon’s bluish light. The NGC1990 is surrounded by “Herbig-Haro” or “HH” bi-polar jets. It is rumored that an 8″ or 10″ telescope at 250x will reveal these globules as 14th magnitude “fuzzy stars”. What do you see?

Until next week? Keep exploring the fantastic Orion region. There are many planetary nebulae and open star clusters (even a galaxy or two) waiting for you! Do not be discouraged if you cannot see some of these things on your first try – astronomy is like anything else – it takes Practice! If you don’t have skies tonight? Have Patience. And if you are still learning what type of conditions it takes to see things at their best? Be Persistent! Practice + Patience + Persistence = Perfection!

Light speed…. ~Tammy Plotner

Posted on by Fraser Cain

Mars Glows at Night

Image credit: ESA
The SPICAM instrument on board ESA?s Mars Express has detected light emissions over the nightside of Mars caused by the production of nitrogen oxide in the atmosphere.

SPICAM is a dual ultraviolet/infrared spectrometer dedicated primarily to the study of the atmosphere and ionosphere of Mars. Spectroscopy of ?airglow? and radiometry are powerful methods for remote sensing investigations of the physics of upper atmospheres of the terrestrial planets.

For instance, Martian ?dayglow? spectra reveal the effect of extreme ultraviolet radiation from the Sun on carbon dioxide in Mars?s upper atmosphere, and show it to be a major heating mechanism and involved in the production of an ionosphere.

?Dayglow? and ?nightglow? effects are emissions of light in the upper atmosphere which are produced when atoms combine to form molecules, releasing energy in the form of photons. Dayglow is visible in the dayside upper atmosphere, and nightglow over the nightside.

The ultraviolet spectrum of the nightglow seen by SPICAM is produced when nitrogen and oxygen atoms combine to produce nitrogen oxide molecules (?recombination?) and release energy.

A similar ultraviolet nightglow on Venus had been detected with Mariner 5 and Pioneer Venus, but the first real evidence for this process was a spectrum acquired with the ESA/NASA International Ultraviolet Explorer satellite which identified the nightglow emissions as coming from nitrogen oxide recombination.

Scientists proposed that nitrogen and oxygen atoms are produced on the Venus day side by a process called ?electron ultraviolet photodissociation?. This is the break-up of oxygen, nitrogen and carbon dioxide molecules by ultraviolet light. The separate atoms were then transported to the nightside where recombination occurs.

These findings were later supported by detailed Pioneer Venus spectra and computer modelling of Venusian atmospheric circulation. Until now, however, this kind of nightglow had never been seen on Mars. It is thought that the mechanism responsible for the nightglow emissions on Mars is the same as that causing the nightglow on Venus.

These nightglow emissions are important tracers of atmospheric transport at high altitudes, which could be used in refining circulation models of the Martian atmosphere.

Original Source: ESA News Release

Posted on by Nancy Atkinson

A Pristine View of the Universe… from the Moon

Image credit: University of Arizona
Over 30 years ago, Dr. Roger Angel came to the University of Arizona, drawn by the favorable conditions for astronomical observing in the Tucson, Arizona area: several telescopes are conveniently nearby, and of course, the weather is wonderfully temperate. But now, Angel proposes to build a telescope in a location somewhat more remote and not quite so balmy: a polar crater on the moon.

Known for his innovations in lightweight telescope mirrors and adaptive optics, Angel now leads a team of scientists from the U.S. and Canada who are exploring the feasibility of building a Deep-Field Infrared Observatory near one of the lunar poles using a Liquid Mirror Telescope (LMT).

This concept is one of 12 proposals that began receiving funding last October from the NASA Institute for Advanced Concepts (NIAC). Each gets $75,000 for six-months of research to make initial studies and identify challenges in development. Projects that make it through the first phase are eligible for as much as $400,000 more over two years.

LMTs are made by spinning a reflective liquid, usually mercury, on a bowl-shaped platform to form a parabolic surface, perfect for astronomical optics. Isaac Newton originally proposed the theory, but the technology to actually create such a device successfully has only recently been developed. Just a handful of LMTs are being used today, including a 6-meter LMT in Vancouver, Canada, and a 3-meter version that NASA uses for its Orbital Debris Observatory in New Mexico.

On Earth, LMTs are limited in size to about 6 meters in diameter because the self-generated wind that comes from spinning the telescope disturbs the surface. Additionally, like other Earth-based telescopes, LMTs are subject to atmospheric absorption and distortion, greatly reducing the range and sensitivity of infrared observing. But the atmosphere-free moon, Angel says, provides the perfect location for this type of telescope while supplying the gravity necessary for the parabolic mirror to form.

The potential of an LMT on the moon is to make a very big telescope. For reference, the Hubble Space Telescope has a 2.4 meter mirror, and the James Webb Space Telescope (JWST) being developed for launch in 2011 will have a 6 meter mirror. The concept for Angel’s NIAC proposal is a 20 meter mirror, but with the research the team has done so far, they are now looking at creating very large mirrors, with 100 meters being the big end option. They are considering smaller LMTs as well. “We obviously can’t go to the moon and make a 100 meter mirror the first thing,” Angel said. “We’re looking at a sequence of scale sizes of 2 meters, 20 meters, and 100 meters, and are looking at what the potential is for each one.” Angel believes the 2 meter telescope could be made without any human presence on the moon, and set up as a robotic telescope, much like the scientific instruments on the Mars rovers are operating now.

The limitation of a liquid mirror is that it only points straight up, so it’s not like a standard telescope that can be pointed in any direction and track objects in the sky. It only looks at the area of sky that is directly overhead.

So, the scientific goal for a LMT is to not look over the whole sky, but to take one area of space and look at it intensely. This type of astronomy has been very “profitable,” as Angel described it, in terms of the wealth of information that?s been gathered. Some of the most productive scientific efforts from the Hubble Space Telescope have been its “Deep Field” photographs.

To be able to look at only one area of space at all times drives Angel and his team to look to one of the lunar poles for the best location for this telescope. As at Earth’s poles, looking straight up from the poles on the moon always provides the same extragalactic field of view. “If we go to the North or South Pole of the moon, we?re going to image one patch of sky all the time, and so that allows you to make an extremely deep integration, much deeper even than the Hubble Deep Field.” Combine that with a large aperture, and this telescope would provide a depth of observation which would be unmatched with any telescope on Earth or in space. “That?s the niche or particular strength of this telescope,” Angel said.

Another upside of liquid mirrors is that they are very inexpensive compared to the process of making a standard mirror by creating, polishing and testing a big, rigid piece of glass, or creating smaller pieces which have to be polished, tested and then joined together very accurately. Also, LMTs don’t need expensive mounts, supports, tracking systems, or a dome.

“The total cost of the James Webb Telescope is expected to exceed a billion dollars, with the price tag on the mirror alone around a quarter of a million dollars,” Angel said. “That mirror is 6 meters, so if we scale that technology to even bigger mirrors in space, we?re eventually going to break the bank, and we won?t be able to afford them by the present technology of making the polished mirror and getting it up to space.”

Even though the 2 meter telescope would be a prototype, it would still be astronomically valuable. “We could do things that are complimentary to the Spitzer Space Telescope and the Webb Telescope, as the 2 meter telescope on the moon would fill the territory in between those two telescopes.” A 20 meter mirror would provide resolution 3 times greater than the JWST, and by integrating, or leaving the “shutter” open for long periods, like a year, objects 100 times fainter could be viewed. A 100 meter mirror would provide data that is off the charts.

One of the challenges in developing an LMT on the moon is to create the bearings to spin the platform smoothly and at a constant speed. Air bearings are used for LMTs on Earth, but with no air on the moon, that is impossible. Angel and his team are looking at cryogenic levitation bearings, similar to what?s used for magnetic levitation trains to get a frictionless motion by using a magnetic field. Angel added, “As a bonus, with the low temperatures on the moon you can do that without expending any energy because you can make a superconducting magnet that allows you to make a levitation bearing that doesn’t require a continuous input of electrical power.”

Angel called the bearings a critical component of the telescope. “With no air on the moon to create wind, there?s no limit to size or reaching the accuracy that you require as long as the bearing is alright,” Angel said.

One evolution of the project since receiving the NIAC funding is the location of the telescope. In the initial proposal, Angel’s team favored the south pole of the moon in the Shackleton crater. But the north pole actually offers a better field of view for extragalactic observation, they realized, and Angel awaits data from the European Space Agency’s SMART-1 lunar orbiter that recently began surveying the polar regions of the moon.

“In the polar regions there are some craters where the sun never illuminates and never heats the ground,” Angel said. “It is extremely cold there, not too far above absolute zero. Rather than build the telescope under such hostile conditions, we would attempt to build the telescope on a peak of the either of the poles, where there would be sunshine almost continuously. This would provide solar power and the conditions would be better for the people living there. All you have to do is put a cylindrical Mylar screen around the telescope to prevent the sun from ever hitting it and it will cool off just like in the bottom of the craters.”

With infrared observing, a cold telescope is vital to be able to see colder and fainter objects in space. Having the telescope at near absolute zero (0 degrees Kelvin, -273 C, -460 F) would be ideal. Since mercury will freeze at those temperatures, another challenge for the project is finding the right liquid to spin for the mirror. Some of the candidates are ethane, methane, and other small hydrocarbons, like the liquids that were found on Titan by the Huygens probe, which landed on Saturn’s largest moon on January 14.

“But these liquids are not shiny, so you have to figure out how to deposit a shiny metal like aluminum directly onto the surface of the liquid,” Angel said. “Normally when we make an astronomical telescope we make the mirrors out of glass, which doesn?t reflect very much and then you evaporate aluminum or silver onto the glass. On the moon we would have to evaporate the metal onto the liquid rather than the glass.”

That’s one of the key areas of research under the NIAC award. In initial studies, Angel’s team has been able to evaporate a metal onto a liquid, although not yet at the cold temperatures required. However, they are encouraged by the results so far.

Angel’s team is atypical for a NIAC project, in that it’s an international collaboration, and NIAC doesn’t fund international partners. “It happens that the world experts on making spinning liquid mirror telescopes are all in Canada, so it was kind of essential that if we’re thinking of doing that on the moon that we bring them in,” Angel said. “Luckily, they have come in on their own ticket, so to speak, and are excited by the project.”

The Canadian members of the team are Emanno Borra, from Laval University in Quebec, who has been researching and building LMTs since the early 1980’s, and Paul Hickson, from University of British Columbia, who, with Borra’s help, built the 6 meter LMT in Vancouver. Other collaborators include Ki Ma at the University of Texas at Houston who is an expert on the cryogenic bearings, Warren Davison from the University of Arizona who is a mechanical engineering expert in telescopes, and graduate student Suresh Sivanandam.

NIAC was created in 1998 to solicit revolutionary concepts from people and organizations outside the space agency that could advance NASA’s missions. The winning concepts are chosen because they “push the limits of known science and technology,” and “show relevance to the NASA mission,” according to NASA. These concepts are expected to take at least a decade to develop.

Angel says that receiving the NIAC award is a great opportunity. “We will undoubtedly write a proposal for Phase II (of the NIAC funding),” he said. “We’ve identified during Phase I what are some of the most critical issues in this project, and what practical steps we should take now. We’ve opened some questions, and there are some simple tests we can do to see if there are any show stoppers or not.”

The biggest hurdle in making the Lunar Infrared Observatory a reality is, most likely, completely out of Angel’s hands. “The moon is a very interesting place to do science,” Angel said. “However, it’s predicated on a substantial commitment of resources by NASA to return to the moon.” Certainly, to build the large 20 or 100 meter telescopes there would have to be a manned presence on the moon. “So,” Angel continued, “by hitching your science in that direction, you become the tail of a very big dog over which you have absolutely no control”?

Angel hopes that NASA and the United States can maintain the momentum of the Vision for Space Exploration and return to the moon. “I think ultimately that moving out into space is something that humans have an urge to do and will do sometime,” Angel said. “When that happens, having interesting things to do once we get there is important. We have to know why we left the surface of this planet to go to the moon. We’re exploring, yes, but we can explore not only the moon, but use that as a place to do scientific research beyond the moon. I think it’s something that in the big picture should happen.”

Nancy Atkinson is a freelance writer and NASA Solar System Ambassador. She lives in Illinois.

Posted on by Fraser Cain

Pluto and Charon Could Have Formed Together

The evolution of Kuiper Belt objects, Pluto and its lone moon Charon may have something in common with Earth and our single Moon: a giant impact in the distant past.

Dr. Robin Canup, assistant director of Southwest Research Institute’s? (SwRI) Department of Space Studies, argues for such an origin for the Pluto-Charon pair in an article for the January 28 issue of the journal Science.

Canup, who currently is a visiting professor at the California Institute of Technology, has worked extensively on a similar “giant collision” scenario to explain the Moon’s origin.

In both the Earth-Moon and Pluto-Charon cases, Canup’s smooth particle hydrodynamic simulations depict an origin in which a large, oblique collision with the growing planet produced its satellite and provided the current planet-moon system with its angular momentum.

While the Moon has only about 1 percent of the mass of Earth, Charon accounts for a much larger 10 to 15 percent of Pluto’s total mass. Canup’s simulations suggest that a proportionally much larger impactor – one nearly as large as Pluto itself – was responsible for Charon, and that the satellite likely formed intact as a direct result of the collision.

According to Canup, a collision in the early Kuiper Belt – a disk of comet-like objects orbiting in the outer solar system beyond Neptune – could have given rise to a planet and satellite with relative sizes and angular rotation characteristics consistent with those of the Pluto-Charon pair. The colliding objects would have been about 1,600 to 2,000 kilometers in diameter, or each about half the size of the Earth’s Moon.

“This work suggests that despite their many differences, our Earth and the tiny, distant Pluto may share a key element in their formation histories. This provides further support for the emerging view that stochastic impact events may have played an important role in shaping final planetary properties in the early solar system,” said Canup.

The “giant impact” theory was first proposed in the mid-1970s to explain how the Moon formed, and a similar mode of origin was suggested for Pluto and Charon in the early 1980s. Canup’s simulations are the first to successfully model such an event for the Pluto-Charon pair.

Simulations published by Canup and a colleague in Nature in 2001 showed that a single impact by a Mars-sized object in the late stages of Earth’s formation could account for the iron-depleted Moon and the masses and angular momentum of the Earth-Moon system.

This was the first model to simultaneously explain these characteristics without requiring that the Earth-Moon system be substantially modified after the lunar forming impact.

This research was supported by the National Science Foundation under grant no. AST0307933.

Original Source: SwRI News Release