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

Posted on by Fraser Cain

Keep an Eye on the Weather in Space

NASA is returning to the Moon–not just robots, but people. In the decades ahead we can expect to see habitats, greenhouses and power stations up there. Astronauts will be out among the moondust and craters, exploring, prospecting, building.

Good thing.

On January 20th, 2005, a giant sunspot named “NOAA 720” exploded. The blast sparked an X-class solar flare, the most powerful kind, and hurled a billion-ton cloud of electrified gas (a “coronal mass ejection”) into space. Solar protons accelerated to nearly light speed by the explosion reached the Earth-Moon system minutes after the flare–the beginning of a days-long “proton storm.”

Here on Earth, no one suffered. Our planet’s thick atmosphere and magnetic field protects us from protons and other forms of solar radiation. In fact, the storm was good. When the plodding coronal mass ejection arrived 36 hours later and hit Earth’s magnetic field, sky watchers in Europe saw the brightest and prettiest auroras in years: gallery.

The Moon is a different story.

“The Moon is totally exposed to solar flares,” explains solar physicist David Hathaway of the Marshall Space Flight Center. “It has no atmosphere or magnetic field to deflect radiation.” Protons rushing at the Moon simply hit the ground–or whoever might be walking around outside.

The Jan. 20th proton storm was by some measures the biggest since 1989. It was particularly rich in high-speed protons packing more than 100 million electron volts (100 MeV) of energy. Such protons can burrow through 11 centimeters of water. A thin-skinned spacesuit would have offered little resistance.

“An astronaut caught outside when the storm hit would’ve gotten sick,” says Francis Cucinotta, NASA’s radiation health officer at the Johnson Space Center. At first, he’d feel fine, but a few days later symptoms of radiation sickness would appear: vomiting, fatigue, low blood counts. These symptoms might persist for days.

Astronauts on the International Space Station (ISS), by the way, were safe. The ISS is heavily shielded, plus the station orbits Earth inside our planet’s protective magnetic field. “The crew probably absorbed no more than 1 rem,” says Cucinotta.

One rem, short for Roentgen Equivalent Man, is the radiation dose that causes the same injury to human tissue as 1 roentgen of x-rays. A typical dental x-ray, for example, delivers about 0.1 rem. So, for the crew of the ISS, the Jan. 20th proton storm was like 10 trips to the dentist–scary, but no harm done.

On the Moon, Cucinotta estimates, an astronaut protected by no more than a space suit would have absorbed about 50 rem of ionizing radiation. That’s enough to cause radiation sickness. “But it would not have been fatal,” he adds.

Right: The Jan. 20th proton storm photographed from space by a coronagraph onboard the Solar and Heliospheric Observatory (SOHO). The many speckles are solar protons striking the spacecraft’s digital camera. [More]

To die, you’d need to absorb, suddenly, 300 rem or more.

The key word is suddenly. You can get 300 rem spread out over a number of days or weeks with little effect. Spreading the dose gives the body time to repair and replace its own damaged cells. But if that 300 rem comes all at once … “we estimate that 50% of people exposed would die within 60 days without medical care,” says Cucinotta.

Such doses from a solar flare are possible. To wit: the legendary solar storm of August 1972.

It’s legendary (at NASA) because it happened during the Apollo program when astronauts were going back and forth to the Moon regularly. At the time, the crew of Apollo 16 had just returned to Earth in April while the crew of Apollo 17 was preparing for a moon-landing in December. Luckily, everyone was safely on Earth when the sun went haywire.

“A large sunspot appeared on August 2, 1972, and for the next 10 days it erupted again and again,” recalls Hathaway. The spate of explosions caused, “a proton storm much worse than the one we’ve just experienced,” adds Cucinotta. Researchers have been studying it ever since.

Cucinotta estimates that a moonwalker caught in the August 1972 storm might have absorbed 400 rem. Deadly? “Not necessarily,” he says. A quick trip back to Earth for medical care could have saved the hypothetical astronaut’s life.

Surely, though, no astronaut is going to walk around on the Moon when there’s a giant sunspot threatening to explode. “They’re going to stay inside their spaceship (or habitat),” says Cucinotta. An Apollo command module with its aluminum hull would have attenuated the 1972 storm from 400 rem to less than 35 rem at the astronaut’s blood-forming organs. That’s the difference between needing a bone marrow transplant ? or just a headache pill.

Modern spaceships are even safer. “We measure the shielding of our ships in units of areal density–or grams per centimeter-squared,” says Cucinotta. Big numbers, which represent thick hulls, are better:

The hull of an Apollo command module rated 7 to 8 g/cm2.

A modern space shuttle has 10 to 11 g/cm2.

The hull of the ISS, in its most heavily shielded areas, has 15 g/cm2.

Future moonbases will have storm shelters made of polyethelene and aluminum possibly exceeding 20 g/cm2.

A typical space suit, meanwhile, has only 0.25 g/cm2, offering little protection. “That’s why you want to be indoors when the proton storm hits,” says Cucinotta.

But the Moon beckons and when explorers get there they’re not going to want to stay indoors. A simple precaution: Like explorers on Earth, they can check the weather forecast–the space weather forecast. Are there any big ‘spots on the sun? What’s the chance of a proton storm? Is a coronal mass ejection coming?

All clear? It’s time to step out.

Original Source: Science@NASA Article

Posted on by Fraser Cain

Biggest Stars Make the Biggest Magnets

Astronomy is a science of extremes–the biggest, the hottest, and the most massive. Today, astrophysicist Bryan Gaensler (Harvard-Smithsonian Center for Astrophysics) and colleagues announced that they have linked two of astronomy’s extremes, showing that some of the biggest stars in the cosmos become the strongest magnets when they die.

“The source of these very powerful magnetic objects has been a mystery since the first one was discovered in 1998. Now, we think we have solved that mystery,” says Gaensler.

The astronomers base their conclusions on data taken with CSIRO’s Australia Telescope Compact Array and Parkes radio telescope in eastern Australia.

A magnetar is an exotic kind of neutron star–a city-sized ball of neutrons created when a massive star’s core collapses at the end of its lifetime. A magnetar typically possesses a magnetic field more than one quadrillion times (one followed by 15 zeroes) stronger than the earth’s magnetic field. If a magnetar were located halfway to the moon, it could wipe the data from every credit card on earth.

Magnetars spit out bursts of high-energy X-rays or gamma rays. Normal pulsars emit beams of low-energy radio waves. Only about 10 magnetars are known, while astronomers have found more than 1500 pulsars.

“Both radio pulsars and magnetars tend to be found in the same regions of the Milky Way, in areas where stars have recently exploded as supernovae,” explains Gaensler. “The question has been: if they are located in similar places and are born in similar ways, then why are they so different?”

Previous research has hinted that the mass of the original, progenitor star might be the key. Recent papers by Eikenberry et al (2004) and Figer et al (2005) have suggested this connection, based on finding magnetars in clusters of massive stars.

“Astronomers used to think that really massive stars formed black holes when they died,” says Dr Simon Johnston (CSIRO Australia Telescope National Facility). “But in the past few years we’ve realized that some of these stars could form pulsars, because they go on a rapid weight-loss program before they explode as supernovae.”

These stars lose a lot of mass by blowing it off in winds that are like the sun’s solar wind, but much stronger. This loss would allow a very massive star to form a pulsar when it died.

To test this idea, Gaensler and his team investigated a magnetar called 1E 1048.1-5937, located approximately 9,000 light-years away in the constellation Carina. For clues about the original star, they studied the hydrogen gas lying around the magnetar, using data gathered by CSIRO’s Australia Telescope Compact Array radio telescope and its 64-m Parkes radio telescope.

By analyzing a map of neutral hydrogen gas, the team located a striking hole surrounding the magnetar. “The evidence points to this hole being a bubble carved out by the wind that flowed from the original star,” says Naomi McClure-Griffiths (CSIRO Australia Telescope National Facility), one of the researchers who made the map. The characteristics of the hole indicate that the progenitor star must have been about 30 to 40 times the mass of the sun.

Another clue to the pulsar/magnetar difference may lie in how fast neutron stars are spinning when they form. Gaensler and his team suggest that heavy stars will form neutron stars spinning at up to 500-1000 times per second. Such rapid rotation should power a dynamo and generate superstrong magnetic fields. `Normal’ neutron stars are born spinning at only 50-100 times per second, preventing the dynamo from working and leaving them with a magnetic field 1000 times weaker, says Gaensler.

“A magnetar goes through a cosmic extreme makeover and ends up very different from its less exotic radio pulsar cousins,” he says.

If magnetars are indeed born from massive stars, then one can predict what their birth rate should be, compared to that of radio pulsars.

“Magnetars are the rare `white tigers’ of stellar astrophysics,” says Gaensler. “We estimate that the magnetar birth rate will be only about a tenth that of normal pulsars. Since magnetars are also short-lived, the ten we have already discovered may be almost all that are out there to be found.”

The team’s result will be published in an upcoming issue of The Astrophysical Journal Letters.

This press release is being issued in conjunction with CSIRO’s Australia Telescope National Facility.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: CfA News Release

Posted on by Fraser Cain

Dr. Seth Shostak Answers Your Questions About SETI

Is there any other way a civilization can be detected other than by EM radiation (IR, UV, radiowave, microwave, etc) detection? What’s the probability of finding an intelligent lifeform in our lifetime? – Alfchemist

Well, sure, there are other possibilities for finding cosmic company. You could look for messages being transmitted by particle beams (even neutrinos), and this has been suggested. But the problem is that these require harder-to-build transmitters and receivers, and are also susceptible to absorption by interstellar gas. So they don’t seem to offer much advantage. The other possibility is to find some evidence of “alien engineering” — maybe sophisticated beings on other worlds have managed to rearrange the stars in their neighborhood, or build huge, starshine-collecting solar panels that we could somehow spot from afar. Some experiments have been done to locate such massive construction projects, but it’s hard to know how to look or even what to look for.

I think it’s likely that the new telescopes being built for SETI will trip across a signal by the year 2025.

The SETI Project and SETI@home have processed a bunch of data. Other than the search for intelligent signals, have you learned anything new about the universe from all this information? – corkft

In fact, not too much. This is rather surprising, because the history of astronomy suggests that whenever you build a new instrument, able to look at a previously unobserved bit of either space or the spectrum, you usually trip across some unexpected object or other. SETI projects have receivers with VERY narrow frequency channels. But there really doesn’t seem to be any natural phenomena that lend themselves to being discovered with such equipment. In a sense this justifies SETI’s assumption that any narrow-band signal would convincingly prove intelligence!

What is the maximum distance at which SETI can detect signals which are not deliberately beamed at us, such as normal radio telecommunications traffic? And are there plans to increase this range? – Steve t

Our best SETI experiments to date could detect Earth-like “leakage” signals at no more than 1 light-year’s distance. So not too far. But keep in mind that (1) our experiments do get more sensitive with time, so this distance will increase, and (2) we’ve only had radio for a century. Aliens, who may have invented this technology thousands or even millions of years ago, will undoubtedly have some transmitters and antenna systems capable of putting out signals far more powerful than what we manage with our erudite and always entertaining commercial television efforts!

To what degree does our SETI search make assumptions about the rate of information transfer? What transfer rates are we currently equipped to detect, and in what modulation modes? – wstevenbrown

We don’t worry at all about modulation, or schemes for encoding messages. That’s something to be considered after you’ve found that their transmitter is on! At the moment, all SETI experiments simply look for narrow-band (typically 1 Hz or narrower) components to a signal… somewhat akin to the “carrier” signal for earthly transmissions, but not limited to those. We also look for slowly pulsing signals, too. But the point is that at least some fraction of the aliens’ transmissions are assumed to put a lot of energy into a narrow bandwidth… making those signal components more easily detectable.

Assuming Big Bang origins, how soon would sufficient astronomical metallicity have occurred to produce a 0.8% or better probability of the formation of CHON-based life supporting planets? Is there any way to evaluate how “typical” is the time required for our evolutionary path to technical competence? – GOURDHEAD

Well this depends on where you are, as the metallicity varies across the Galaxy. I can’t speak to “0.8% or better probability,” as I don’t know where this number comes from and there’s no way to estimate it anyway. But put it this way: even in the oldest globular cluster star systems in our Galaxy — choked with stars that were born more than 10 billion years ago — there’s enough of the heavy elements (“metals”) to make earth-like worlds. I don’t think there was much “dead time” between the formation of galaxies and the growth of the heavy element abundance to the point where life was possible.

Do the recent conclusions that radio signals from advanced civilizations may be indistinguishable from the thermal radiation of their parent stars give you second thoughts on the likelihood of finding a positive signal? – Greg

Nope. It’s true that an optimally encoded signal would look like (white) noise, and I’m sure that advanced societies will be very good at encoding. But there are always applications for which you need some narrow-band signals. For example, you might have a solar-system-wide GPS network for interplanetary navigation. Or big radar sets for tracking incoming, long-period comets. Not to mention a deliberate broadcast to galactic brethren…!

How will the new Allen Telescope Array (ATA) be incorporated into SETI ? – 6EQUJ5

In the summer of 2005, there will be 32 antennas working at the ATA, and the SETI Institute will initiate a scan of the densest parts of the galactic plane. This is a straightforward SETI experiment that will scrutinize lots of stars, albeit stars that are (on average) thousands of light-years away. As the ATA gets built out to 350 antennas, it will switch over to targeting individual, relatively nearby (less than 1,000 light-years) star systems. By 2025, it should be able to check out as many as a million such systems.

Should an alien signal be identified, what would be the protocol for alerting the people of Earth? Would the news be limited to a few,or would be announced for all to listen? – Duane

Well, there’s no secrecy in SETI, and it’s been our experience that whenever we pick up an “interesting” signal, the media are on top of the story right away. So you can be sure you’ll be reading about any signal long before the SETI researchers themselves have fully checked it out to convince themselves that it isn’t interference or a software bug!

Posted on by Fraser Cain

Moss Grows in a Spiral… in Space

Experiments on moss grown aboard two space shuttle Columbia missions showed that the plants didn’t behave as scientists expected them to in the near-absence of gravity.

The common roof moss (Ceratodon purpureus) grew in striking, clockwise spirals, according to Fred Sack, the study’s lead investigator and a professor of plant cellular and molecular biology at Ohio State University.

He and his colleagues noted this even in moss cultures grown aboard the second of the two space shuttle missions, STS-107, which had disintegrated upon its reentry in early 2003. Most of the hardware that contained the moss was later recovered on the ground, with some of the moss cultures still intact.

The researchers expected random, unorganized growth, as seen with every other type of plant flown in space.

“We don’t know why moss grew non-randomly in space, but we found distinct spiral patterns,” Sack said.

He and his colleagues report their findings in the current online edition of the journal Planta.

Common roof moss is a relatively primitive plant in which certain cells, called tip cells, are guided by gravity in their growth. This gravity response is only seen when moss is kept in the dark, as light overrides gravity’s effect.

Moss originates from chains of cells with growth only taking place in the tip-most cell of a chain. When grown in the dark, the tip cells grow away from gravity’s pull this gets the cells out of the soil and into the light.

The way these tip cells respond to gravity is exceptional, Sack said. In most plants, gravity guides the growth of roots or stems, which are made up of many cells. But in moss it is just a single cell that both senses and responds to gravity.

Common roof moss was grown in Petri dishes in lockers aboard two Columbia shuttle missions the first in 1997 and the other in early 2003. Although most of the experimental moss hardware from this mission was later recovered on the ground, only 11 of the 87 recovered cultures grown on this flight were usable.

Astronauts followed similar experimental procedures on both flights. The astronauts chemically fixed the moss cultures before each mission reentered Earth’s atmosphere. This process stopped all growth in the moss.

Control studies conducted at Kennedy Space Center in Florida used hardware and procedures similar to those used aboard each flight. However, these moss cultures were either kept stationary or turned at a slow spin on a clinostat a machine that resembles a record turntable placed on its edge, and is used to negate the effects of gravity.

On earth gravity controls the direction of moss growth so thoroughly that it grows straight away from the center of the earth, just like shoots in a field of corn. In space, scientists expected the cells to grow erratically in all directions since there was no gravity cue.

Instead, the moss grew non-randomly in two successive types of patterns: The first pattern resembled that of spokes in a wheel, where the cells grew outward from where they were originally sown. Later, the tips of the filaments grew in arcs so that the entire culture showed clockwise spirals. The same patterns were found when the moss was grown on a clinostat on the ground.

Even with the limited data from STS-107, 10 of the 11 salvageable moss cultures showed this kind of strong radial growth and spiraling.

Ground controls grown in normal conditions of gravity grew as moss normally would on earth.

The results are unusual, Sack said, as this is the first time researchers report seeing this kind of plant growth response in space.

“Unlike the ordered response of moss cells in space, other types of plants grow randomly,” he said. “So in moss, gravity must normally mask a default growth pattern. This pattern is only revealed when the gravity signal is lost or disrupted.

“The fascinating question is why would moss have a backup growth response to conditions it has never experienced on earth? Perhaps spirals are a vestigial growth pattern, a pattern that later became masked when moss evolved the ability to respond to gravity.

Sack conducted the study with Volker Kern, who is now at Kennedy Space Center and was at Ohio State at the time of the study; David Reed, with Bionetics Corp. based at Kennedy Space Center; with former Ohio State colleagues Jeanette Nadeau, Jochen Schwuchow and Alexander Skripnikov; and with Jessica Lucas, a graduate student in Sack’s lab.

Support for this research came from the Exploration Systems Mission Directorate of the National Aeronautics and Space Administration.

Original Source: Ohio State University News Release

Posted on by Fraser Cain

New Spacecraft Will Map the Edge of Our Solar System

A satellite that will make the first map of the boundary between the Solar System and interstellar space has been selected as part of NASA’s Small Explorer program. The Interstellar Boundary Explorer (IBEX) mission will be launched in 2008.

IBEX is the first mission designed to detect the edge of the Solar System. As the solar wind from the sun flows out beyond Pluto, it collides with the material between the stars, forming a shock front. IBEX contains two neutral atom imagers designed to detect particles from the termination shock at the boundary between the Solar System and interstellar space.

IBEX also will study galactic cosmic rays, energetic particles from beyond the Solar System that pose a health and safety hazard for humans exploring beyond Earth orbit. IBEX will make these observations from a highly elliptical orbit that takes it beyond the interference of the Earth’s magnetosphere. Dr. David McComas of Southwest Research Institute in San Antonio will lead IBEX. It will cost approximately $134 million. The Small Explorer program (SMEX) consists of rapid, small, and focused science exploration missions.

“Explorer missions continue to efficiently address NASA’s objectives, because of the competitive character of the Explorer Program. Dr. McComas and his co-investigators submitted a compelling proposal. It had sufficient details to convince other independent scientists, engineers, technologists, cost analysts, and program managers this is an exciting and breakthrough experiment for NASA to sponsor,” said NASA’s Deputy Associate Administrator for the Science Mission Directorate, Dr. Ghassem Asrar.

“The mission will continue the NASA Explorer Program’s successful record of scientific exploration of space over the past four decades, and it supports the Vision for Space Exploration,” Asrar added.

NASA has decided to continue studying another proposed mission, the Nuclear Spectroscopic Telescope Array (NuSTAR). It is the first telescope capable of detecting black holes in the local universe with 1,000 times more sensitivity than previous missions sensitive to energetic X-rays. A decision on proceeding to flight development with NuSTAR will be made by early 2006. Dr. Fiona Harrison of the California Institute of Technology, Pasadena, Calif. is the Principal Investigator for NuSTAR.

The Explorer Program is designed to provide frequent, low-cost access to space for physics and astronomy missions with small to mid-sized spacecraft. NASA has successfully launched six SMEX missions since 1992. The missions include the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) launched in February 2002, and the Galaxy Evolution Explorer launched in April 2003. The next SMEX mission is the Aeronomy of Ice in the Mesosphere (AIM) mission, scheduled to launch in September 2006. AIM will study the Earth’s highest clouds for clues to climate change.

The selected proposals were among 29 SMEX and eight mission-of-opportunity proposals submitted to NASA in May 2003. They were in response to an Explorer Program Announcement of Opportunity issued in February 2003. NASA selected six proposals in November 2003 for detailed feasibility studies.

Funded by NASA, up to $450,000 each, these studies focus on cost, management, and technical plans, including small business involvement and educational outreach. NASA’s Goddard Space Flight Center, Greenbelt, Md., manages the Explorer Program for the Science Mission Directorate.

For information and artist’s concepts of these missions on the Internet, visit: NuSTAR

For information about NASA’s Explorer Program on the Internet, visit:
http://explorers.gsfc.nasa.gov/

Original Source: NASA News Release

Posted on by Fraser Cain

Dark Matter Halos Were the First Objects

Ghostly haloes of dark matter as heavy as the earth and as large as our solar system were the first structures to form in the universe, according to new calculations from scientists at the University of Zurich, published in this week’s issue of Nature.

Our own galaxy still contains quadrillions of these halos with one expected to pass by Earth every few thousand years, leaving a bright, detectable trail of gamma rays in its wake, the scientists say. Day to day, countless random dark matter particles rain down upon the Earth and through our bodies undetected.

“These dark matter haloes were the gravitational ‘glue’ that attracted ordinary matter, eventually enabling stars and galaxies to form,” said Prof. Ben Moore of the Institute for Theoretical Physics at the University of Zurich, a co-author on the Nature report. “These structures, the building blocks of all we see today, started forming early, only about 20 million years after the big bang.”

Dark matter comprises over 80 percent of the mass of the universe, yet its nature is unknown. It seems to be intrinsically different from the atoms that make up matter all around us. Dark matter has never been detected directly; its presence is inferred through its gravitational influence on ordinary matter.

The Zurich scientists based their calculation on the leading candidate for dark matter, a theoretical particle called a neutralino, thought to have been created in the big bang. Their results entailed several months of number crunching on the zBox, a new supercomputer designed and built at the University of Zurich by Moore and Drs. Joachim Stadel and Juerg Diemand, co-authors on the report.

?Until 20 million years after the big bang, the universe was nearly smooth and homogenous?, Moore said. But slight imbalances in the matter distribution allowed gravity to create the familiar structure that we see today. Regions of higher mass density attracted more matter, and regions of lower density lost matter. Dark matter creates gravitational wells in space and ordinary matter flows into them. Galaxies and stars started to form as a result about 500 million years after the big bang, whereas the universe is 13.7 billion years old.

Using the zBox supercomputer that harnessed the power of 300 Athlon processors, the team calculated how neutralinos created in the big bang would evolve over time. The neutralino has long been a favoured candidate for “cold dark matter,” which means it does not move fast and can clump together to create a gravitational well. The neutralino has not yet been detected. This is a proposed “supersymmetric” particle, part of a theory that attempts to rectify inconsistencies in the standard model of elementary particles.

For the past two decades scientists have believed that neutralinos could form massive dark matter haloes and envelope entire galaxies today. What has emerged from the Zurich team’s zBox supercomputer calculation are three new and salient facts: Earth-mass haloes formed first; these structures have extremely dense cores enabling quadrillions to have survived the ages in our galaxy; also these “miniature” dark matter haloes move through their host galaxies and interact with ordinary matter as they pass by. It is even possible that these haloes could perturb the Oort cometary cloud far beyond Pluto and send debris through our solar system.

?Detection of these neutralino haloes is difficult but possible?, the team said. The halos are constantly emitting gamma rays, the highest-energy form of light, which are produced when neutralinos collide and self-annihilate.

“A passing halo in our lifetime (should we be so lucky), would be close enough for us to easily see a bright trail of gamma rays,” said Diemand, now at the University of California at Santa Cruz.

The best chance to detect neutralinos, however, is in galactic centres, where the density of dark matter is the highest, or in the centres of these migrating Earth-mass neutralino haloes. Denser regions will provide a greater chance of neutralino collisions and thus more gamma rays. “This would still be difficult to detect, like trying to see the light of a single candle placed on Pluto,” said Diemand.

NASA’s GLAST mission, planned for launch in 2007, will be capable of detecting these signals if they exist. Ground-based gamma-ray observatories such as VERITAS or MAGIC might also be able to detect gamma rays from neutralino interactions. In the next few years the Large Hadron Collider at CERN in Switzerland will confirm or rule out the concepts of supersymmetry.

Images and computer animations of a neutralino halo and early structure in the universe based on computer simulations are available at http://www.nbody.net

Albert Einstein and Erwin Schr?dinger were amongst the previous professors working at the Institute for Theoretical Physics at the University of Zurich, who made substantial contributions to our understanding of the origin of the universe and quantum mechanics. The year 2005 is the centenary of Einstein’s most remarkable work in quantum physics and relativity. In 1905 Einstein earned his doctorate from the University of Zurich and published three science-changing papers.

Note to editors: The innovative supercomputer designed by Joachim Stadel and Ben Moore is a cube of 300 Athlon processors interconnected by a two-dimensional high-speed network from Dolphin/SCI and cooled by a patented airflow system. Refer to http://krone.physik.unizh.ch/~stadel/zBox/ for more details. Stadel, who led the project, noted: “It was a daunting task assembling a world-class supercomputer from thousands of components, but when it was completed it was the fastest in Switzerland and the world’s highest density supercomputer. The parallel simulation code we use splits up the calculation by distributing separate parts of the model universe to different processors.”

Original Source: Institute for Theoretical Physics ? University of Zurich News Release

Posted on by Fraser Cain

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