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

Not Getting the Newsletter?

If you’ve signed up to receive Universe Today for free by email, but you haven’t been getting them, you’ll need to see if your email provider has set up some kind of SPAM-blocking software. Unfortunately, the Universe Today newsletter smells like SPAM to some of these blocking programs, and it’ll never reach you. Check to see if it’s automatically being dumped into your junk mail folder. Complain to your system administrator. Demand your Universe… today!

Alternatively, you can always join the Universe Today Gmail swap in the forum. I love Gmail, especially since it doesn’t mark Universe Today as SPAM – wise move Google. If you want an invite, visit the forum. If you’ve got invites to spare, visit the forum.

Fraser Cain
Publisher
Universe Today

Posted on by Fraser Cain

Expedition 10 Completes Spacewalk

Image credit: NASA
The residents of the International Space Station ventured outside today for a 5-hour, 28-minute spacewalk to install a work platform, cables and robotic and scientific experiments on the exterior of the Zvezda Service Module.

Clad in Russian Orlan spacesuits, Expedition 10 Commander and NASA Science Officer Leroy Chiao and Flight Engineer Salizhan Sharipov left the Pirs Docking Compartment airlock at 1:43 a.m. CST and quickly set up tools and tethers for their excursion. With no one left inside, Station systems were either deactivated or put in autonomous operation for the duration of the spacewalk. Hatches were also closed between the U.S. and Russian segments of the complex in the unlikely event the crew would not have been able to return to the outpost.

The first order of business was the installation of a Universal Work Platform at the forward end of the large conical section of Zvezda. Atop the platform they mounted a German commercial experiment called Rokviss (Robotics Component Verification on ISS).

The Rokviss consists of a small double-jointed manipulator arm, an illumination system and a power supply. An antenna for the robotic device to receive commands was also installed by Chiao and Sharipov along with cabling. At first the antenna did not receive the proper power. Chiao and Sharipov returned to the antenna work site and remated two electrical connectors. Russian engineers then reported that the Rokviss system was operating normally.

The system is designed to be commanded by operators on the ground in Germany. It can also be operated by the crew from a workstation inside Zvezda. Rokviss will test the ability of lightweight robotic joints to operate in the vacuum of space for future assembly work or satellite repair and servicing.

Chiao and Sharipov moved a Japanese commercial experiment from one bracket on the outside of Zvezda to an adjacent bracket. The experiment, first deployed on Station by the Expedition 3 crew in October 2001, resembles an open attach? case and is designed to collect data on micrometeoroid impacts and the effect of the microgravity environment on a number of materials housed on witness plates.

Chiao and Sharipov then moved to another section of Zvezda to inspect nearby environmental system vents that are used for the Elektron oxygen-generator, the Vozdukh carbon dioxide scrubber and a particle contaminant purification device.

Sharipov reported that he saw both a white and brownish residue near the Elektron and Vozdukh ports and what appeared to be an oily substance on insulation surrounding the ports. Russian specialists added the task to the spacewalk a few weeks ago in light of recent technical problems with those systems, and will analyze photos taken by Sharipov to see if any corrosion or clogging of the vent ports may have contributed to periodic problems with those components.

As the spacewalk drew to a close, Chiao and Sharipov installed a Russian experiment called Biorisk near the hatch to the Pirs airlock. Biorisk consists of several canisters on a bracket that contain microorganisms and materials that will collect data on the effect of the space environment for ecological analysis back on Earth.

With their work complete, Chiao and Sharipov returned to Pirs and closed the hatch at 7:11a.m. CST to complete their spacewalk. After repressurizing Pirs, Chiao and Sharipov were scheduled to return to the Station, remove their spacesuits, reactivate the ISS systems and open the hatches to the U.S. segment. The crew will begin its sleep period early this afternoon and enjoy an off-duty day on Thursday.

It was the first spacewalk for Sharipov and Chiao?s fifth. The excursion was the 57th in support of ISS assembly and maintenance, the 32nd staged from the ISS itself and the 14th from Pirs. A total of 343 hours and 45 minutes of spacewalking time has been logged in the Station?s lifetime.

Chiao and Sharipov are scheduled to conduct a second spacewalk in late March to install additional equipment for the maiden arrival of the European Space Agency?s ?Jules Verne? Automated Transfer Vehicle (ATV) cargo ship. The unpiloted cargo carrier is targeted for launch late this year.

For more on NASA, the crew’s activities aboard the Space Station, future launch dates and Station sighting opportunities from anywhere on the Earth, visit: http://www.nasa.gov

The next International Space Station Status report will be issued on Friday, Jan. 28, or earlier if events warrant.

Original Source: NASA News Release

Posted on by Fraser Cain

SMART-1’s First Image of the Moon

Image credit: ESA
ESA’s SMART-1 captured its first close-range images of the Moon this January, during a sequence of test lunar observations from an altitude between 1000 and 5000 kilometres above the lunar surface.

SMART-1 entered its first orbit around the Moon on 15 November 2004. It has spent the two months following spiralling down to the Moon and testing its array of instruments.

The first four days after being captured by the lunar gravity were very critical. There had been the risk, being in an ‘unstable’ trajectory, of escaping the Moon’s orbit or crashing onto the surface. Because of this, the electric propulsion system (or ‘ion engine’) started a thrust to stabilise the capture.

The ion engine was switched on until 29 December, allowing SMART-1 to make ever-decreasing loops around the Moon. The engine was switched off between 29 December and 3 January 2005 to allow scientists to start observations. At this point, the AMIE camera took the close-up lunar images. The engine was switched off again to optimise fuel consumption on 12 January, and SMART-1 will spend until 9 February making a medium resolution survey of the Moon, taking advantage of the favourable illumination conditions.

ESA’s SMART-1 Project Scientist Bernard Foing said “A sequence of test lunar observations was done in January at distances between 1000 and 5000 kilometres altitude, when the electric propulsion was paused. We are conducting more survey test observations until the electric propulsion resumes from 9 February to spiral down further towards the Moon. SMART-1 will arrive on 28 February at the initial orbit with altitudes between 300 and 3000 kilometres to perform the first phase of nominal science observations for five months.”

The first close-up image shows an area at lunar latitude 75? North with impact craters of different sizes. The largest crater shown here, in the middle left of the image, is Brianchon. The second largest, at the bottom of the image, is called Pascal.

At low illumination angles, the crater shadows allow scientists to derive the height of crater rims.

“This image was the first proof that the AMIE camera is still working well in lunar orbit,” says AMIE Principal Investigator Jean-Luc Josset of Space-X.

The composite images shown here were created to show larger-scale features. The first mosaic shows the complex impact crater Pythagoras and the strip of images (bottom) was produced from images taken consecutively along one orbit.

Starting with this mosaic, SMART-1 scientists expect to build up a global medium-resolution context map, where high-resolution images later observed from lower altitude can be integrated.

Original Source: ESA News Release

Posted on by Fraser Cain

Milky Way’s Black Hole Was Active Recently

The centre of our galaxy has been known for years to host a black hole, a ‘super-massive’ yet very quiet one. New observations with Integral, ESA’s gamma-ray observatory, have now revealed that 350 years ago the black hole was much more active, releasing a million times more energy than at present. Scientists expect that it will become active again in the future.

Most galaxies harbour a super-massive black hole in their centre, weighing a million or even a thousand million times more than our Sun.

Our galaxy too, the Milky Way, hosts a super-massive black hole at its centre. Astronomers call it Sgr A* (pronounced ‘Sagittarius A star’) from its position in the southern constellation Sagittarius, ‘the archer’.

In spite of its enormous mass of more than a million suns, Sgr A* appears today as a quiet and harmless black hole. However, a new investigation with ESA’s gamma-ray observatory Integral has revealed that in the past Sgr A* has been much more active. Data clearly show that it interacted violently with its surroundings, releasing almost a million times as much energy than it does today.

This result has been obtained by a international team of scientists led by Dr Mikhail Revnivtsev (Space Research Institute, Moscow, Russia, and Max Planck Institute for Astrophysics, Garching, Germany). As Revnivtsev explains, “About 350 years ago, the region around Sgr A* was literally swamped in a tide of gamma rays.”

This gamma-ray radiation is a direct consequence of Sgr A*’s past activity, in which gas and matter trapped by the hole’s gravity are crushed and heated until they radiate X-rays and gamma rays, just before disappearing below the ‘event horizon’ – the point of no return from which even light cannot escape.

The team were able to unveil the history of Sgr A* thanks to a cloud of molecular hydrogen gas, called Sgr B2 and located about 350 light-years away from it, which acts as a living record of the hectic black hole’s past.

Because of its distance from the black hole, Sgr B2 is only now being exposed to the gamma rays emitted by Sgr A* 350 years ago, during one of its ‘high’ states. This powerful radiation is absorbed and then re-emitted by the gas in Sgr B2, but this process leaves behind an unmistakable signature.

“We are now seeing an echo from a sort of natural mirror near the galactic centre – the giant cloud Sgr B2 simply reflects gamma rays emitted by Sgr A* in the past,” says Revnivtsev. The flash was so powerful that the cloud became fluorescent in the X-rays and was even seen with X-ray telescopes before Integral. However, by showing how high-energy radiation is reflected and reprocessed by the cloud, Integral allowed scientists to reconstruct for the first time the hectic past of Sgr A*.

The high state or ‘activity’ of black holes is closely linked to the way in which they grow in size. Super-massive black holes are not born so big but, thanks to their tremendous gravitational pull, they grow over time by sucking up the gas and matter around them. When the matter is finally swallowed, a burst of X-rays and gamma rays results. The more voracious a black hole, the stronger the radiation that erupts from it.

The new Integral discovery solves the mystery of the emission from super-massive but weak black holes, such as Sgr A*. Scientists already suspected that such weak black holes should be numerous in the Universe, but they were unable to tell how much energy and of which type they emit. “Just a few years ago we could only imagine a result like this,” Revnivtsev says. “But thanks to Integral, we now know it!”

As for the duration of the latest high state of Sgr A*, 350 years ago, Revnivtsev and his team have evidence that it must have lasted at least ten years and probably much longer. The team also expect that Sgr A* will become bright again in the foreseeable future. Detecting the next burst would provide much needed information about the duty cycle of super-massive black holes.

Original Source: ESA News Release