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Huge Outburst from a Magnetar

by Paul Gilster | Jun 18, 2009 | Deep Sky Astronomy & Telescopes | 6 Comments

We get yet another example of space-based observatories complementing each other with the recent outburst of X-rays and gamma rays detected last August. The Swift satellite first noted the event on August 22, while the European Space Agency's XMM-Newton satellite began making detailed spectral studies of the radiation twelve hours later, followed by the Integral observatory. The outburst went on for more than four months, accompanied by hundreds of smaller bursts. The source for these events was a magnetar, a type of neutron star that is the most highly magnetized object known, with a magnetic field some 10,000 million times stronger than Earth's. The new magnetar, christened SGR 0501+4516, is of the type known as Soft Gamma-Ray Repeaters (SGR), and is the first such found in the last decade. Magnetars are known for spectacular periods of irregular burst activity, changing their luminosity up to ten orders of magnitude on timescales of just a few milliseconds. We occasionally discuss...

Two Angles on Meteorites

by Paul Gilster | Jun 17, 2009 | Asteroid and Comet Deflection | 7 Comments

Meteorites are in the news in two starkly different ways this week, but I'll lead with a story that has implications for how planetary systems like ours are born. Philipp Heck (University of Chicago) and colleagues have been analyzing interstellar grains from the Murchison meteorite, a large object that fell near the town of Murchison, Victoria in Australia in 1969. The Murchison grains are thought to have been blown into space by dying stars long before the formation of Earth. We'd like to know more about such grains because they became incorporated into the earliest solids forming in the Solar System, and hence offer a window into that era. Moreover, their composition helps us understand a bit more about their history. "The concentration of neon," says Heck, "produced during cosmic-ray irradiation, allows us to determine the time a grain has spent in interstellar space." Image: A fragment of the Murchison meteorite. Copyright New England Meteoritical Services, 2001. The...

Notes & Queries 6/16/09

by Paul Gilster | Jun 16, 2009 | Culture and Society | 18 Comments

Life Beneath the Ice Three kilometers down in the Greenland ice sheet is what I call an extreme environment. Even so, Penn State researchers have been able to bring a bacterium called Herminiimonas glaciei back to life after a dormancy of 120,000 years in these conditions. The work involved incubating the samples at 2 degrees Celsius for seven months, then at 5 degrees Celsius for a further four and a half, a patient process rewarded by the appearance of the purple-brown bacteria. Ten to fifty times smaller than E. coli, Herminiimonas glaciei evidently used its size to survive in liquid veins amongst the ice crystals. Jennifer Loveland-Curtze describes the find: "These extremely cold environments are the best analogues of possible extraterrestrial habitats. The exceptionally low temperatures can preserve cells and nucleic acids for even millions of years. H. glaciei is one of just a handful of officially described ultra-small species and the only one so far from the Greenland ice...

A Longer Life for Earth’s Biosphere?

by Paul Gilster | Jun 15, 2009 | Astrobiology and SETI | 15 Comments

If we can find a way to double the lifespan of Earth's biosphere, we'll have changed the odds for finding extraterrestrial civilizations. After all, the amount of time an advanced culture can exist is one of the variables in the famous Drake equation, which estimates how many intelligent civilizations there are in the Milky Way. Lengthen potential habitability and you give any civilization that much more chance to spread into the cosmos. Thus recent work out of Caltech intrigues us in several directions. Joseph Kirschvink and colleagues look at effects that could add a billion years on to our planet's projected habitability. Consider: Earth took some four billion years to develop intelligent life, leaving us about a billion before our planet becomes uninhabitable. That result would be caused by a brighter and hotter Sun, the loss of carbon dioxide in the atmosphere through the weathering of rocks, and the eventual evaporation of water from the oceans, leaving nothing alive. Reducing...

Modeling an Interstellar Future

by Paul Gilster | Jun 13, 2009 | Culture and Society | 3 Comments

The bet between Tibor Pacher and myself continues to draw emails, proving that my friend Tibor was right when he saw an interstellar wager as a teaching opportunity. I still maintain that an interstellar mission will not be launched anywhere near as early as 2025, but Tibor does have his advocates, as you can see on the Long Bets site. Moreover, it's been useful to plug in distances and velocities for a 2000-year mission to a place like Proxima Centauri when I speak to audiences about how large the distance between the stars really is. 2000 years is a long time, but we're still talking 650 kilometers per second, and just 20 years to the Oort Cloud! And as a guy who used to build model airplanes back in my youth, first in plastic and then from balsa wood (wonderful memories of working with kits of World War I and II aircraft from Guillow), I can relate to Tibor's latest venture. MiniSpaceWorld is an attempt to create, at a European site still to be determined, a wide-ranging exhibit...

Earthlight’s Bio-signature Measured

by Paul Gilster | Jun 12, 2009 | Astrobiology and SETI | 5 Comments

Among the most interesting of the future missions now being weighed by NASA, TESS (the Transiting Exoplanet Survey Satellite) would help scientists using the James Webb Space Telescope know where to look for Earth-like planets around nearby stars. While the invaluable Kepler mission scans 100,000 distant stars, hoping to gain statistics on Earth-sized exoplanets, TESS would have a different aim, looking for transiting terrestrial worlds around only the brightest stars. A 2012 launch is possible if the mission is approved. Here's Greg Laughlin (UC-Santa Cruz) on TESS' possibilities: TESS... provides the cheapest, shortest, and most direct path to the actual characterization of a potentially habitable planet. Included in the 2.5 million brightest stars are a substantial number of M dwarfs. Detailed Monte-Carlo simulations indicate that there's a 98% probability that TESS will locate a potentially habitable transiting terrestrial planet orbiting a red dwarf lying closer than 50 parsecs....

A Planetary Detection in Andromeda?

by Paul Gilster | Jun 11, 2009 | Exoplanetary Science | 10 Comments

Gravitational microlensing has been actively employed in the search for MACHOs (Massive Astrophysical Compact Halo Objects) in the galactic halo, although with ambiguous results. The idea here is to find large, dark objects by detecting the microlensing effects they produce on stars behind them. While these dark matter studies have looked toward the Large Magellanic Cloud, we are using the same technique elsewhere in the planet hunt, finding that exoplanets can magnify the light of stars behind them in the galactic bulge, producing a clear detection. Remember, for this kind of work, you want a dense background field of stars because the alignment needed for microlensing is obviously rare. The Magellanics are ideal, as is the galactic bulge, and so, for that matter, is M31, the Andromeda galaxy. And if our early exoplanet work, relying on radial velocity and transit methods, has naturally produced large planets in the Jupiter class, microlensing can be quite effective at smaller...

Planets Forming Around a Close Binary

by Paul Gilster | Jun 10, 2009 | Exoplanetary Science | 7 Comments

Planets around binary stars continue to be a major interest here, given our fascination with nearby Alpha Centauri. Thus the recent radio interferometry images captured by the Submillimeter Array radio telescope system (Mauna Kea) come right to the top of the queue. We're looking at a young binary system called V4046 Sagittarii, providing a glimpse of planetary system formation occurring around two stars of roughly the Sun's mass. This system is approximately 240 light years from our own. Image: Submillimeter Array image of the rotating, gaseous disk surrounding the young twin-star system V4046 Sagittarii (located at the white dot in the image). Note the size of the V4046 Sagittarii disk relative to the orbit of Neptune, shown to scale at the lower right (the filled oval at lower left represents the size of the smallest structures that could be detected in the image). The disk is tipped from our perspective, such that it appears as elliptical rather than circular. The image is...

Alpha Centauri Hunt Intensifies

by Paul Gilster | Jun 9, 2009 | Exoplanetary Science | 20 Comments

I love Greg Laughlin's remark to the Washington Post's Joel Achenbach in last week's article Astronomers Seek New Home Closer to Home. Having discussed Debra Fischer's ongoing search for Alpha Centauri planets and his own theories on planet formation around binary stars, Laughlin points out where we stand today: "We have what is to all appearances by far the best planet in the galaxy. And we have no workable backup plan." The Washington Post article doubtless draws on Lee Billings' earlier piece in SEED Magazine called The Long Shot, which discusses with an elegance rare in science writing the attempt to find planets around the Centauri stars by Fischer as well as Michel Mayor's Geneva team. Mayor has been using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument at La Silla, the Cadillac of radial velocity instrumentation (and boy does that auto industry reference date me!). Competition can work wonders, and having two teams on the case can only bode well for quick...

Tuning Up the Interstellar Ramjet

by Paul Gilster | Jun 8, 2009 | Advanced Rocketry | 15 Comments

Catching my eye in the latest Carnival of Space, hosted by Brian Wang at Next Big Future, is Adam Crowl's write-up of a rethinking of an exotic ramjet technology. Robert Bussard put the interstellar ramjet into the public eye back in 1960 in a paper proposing that a starship moving fast enough would be able to use the hydrogen between the stars as a source of fuel, enabling a constant acceleration at one g. You'll recognize the Bussard ramjet in Poul Anderson's classic novel Tau Zero (originally published in Galaxy in 1967 as To Outlive Eternity). The Problem with Slow Fusion Anderson's 'Leonora Christine' was a runaway starship, accelerating ever closer to lightspeed until she was punching through entire galaxies in times experienced by the crew as mere minutes. But we don't have to get quite that extreme with the Bussard idea. It's built around the premise of gathering fuel along the way so as to avoid the vast mass ratio problems of conventional rocketry. We can imagine an...

SETA: Finding a ‘Graveyard Civilization’

by Paul Gilster | Jun 5, 2009 | Astrobiology and SETI | 38 Comments

Imagine an extraterrestrial civilization that manages to colonize the entire galaxy. Then imagine the colonizing civilization collapsing so definitively that no trace of its existence has yet been detected, at least from our planet. We can call it, as Jacob Haqq-Misra and Seth Baum (Pennsylvania State University) do in a recently released paper, a 'graveyard civilization,' one whose remains might still be accessible provided we know where and how to look. Pushing the Limits of Growth What could bring down such a civilization? The idea here is that we can explain the Fermi paradox ('Where are they?') by assuming that exponential growth is not a sustainable development pattern for intelligent civilizations. The authors draw on human experience in analyzing this possibility. Here's the gist of it: The consequences of unsustainable development are often dire. In many documented cases, resource depletion caused by human activities has led to the permanent collapse of human populations,...

Slow Weather on Titan

by Paul Gilster | Jun 4, 2009 | Outer Solar System | 8 Comments

With a dense atmosphere of nitrogen and methane, Titan is the only moon in our Solar System that shares Earth-like characteristics in climate. But Titan's climate, receiving one hundred times less sunlight at ten times Earth's distance from the Sun, operates at a much slower pace. The seasons on the distant moon last more than seven Earth years, and the motion of its clouds is slow and deliberate. We've had a good look via the Cassini spacecraft at the movement of those clouds, some two hundred of them being examined between July 2004 and December 2007 in a study of global circulation patterns. Summer changes to fall at the equinox in August of this year. We're at a time when the circulation models say clouds in the southern latitudes should have already disappeared, but it's clear from the Cassini imagery that many clouds remained as late as 2007. Image: This infrared image of Saturn's moon Titan shows a large burst of clouds in the moon's south polar region. These clouds form and...

Antimatter Propulsion: A Critical Look

by Paul Gilster | Jun 3, 2009 | Antimatter | 38 Comments

Antimatter's allure for deep space propulsion is obvious. If matter is congealed energy, we need to find the best way to extract that energy, and our existing rockets are grossly inefficient. Even the best chemical rocket pulls only a billionth of the energy available in the atoms of its fuel, while a fission reaction, powerful as it seems, is tapping one part in a thousand of what is available. Fusion reactions like those in a hydrogen bomb use up something on the order of one percent of the total energy within matter. But antimatter can theoretically unlock all of it. Freeing Trapped Energy The numbers are startling. A kilogram of antimatter, annihilating with ordinary matter, can produce ten billion times the amount of energy released when a kilogram of TNT explodes. Heck, a single gram of antimatter, which is about 1/25th of an ounce, would get you as much energy as you could produce from the fuel tanks of two dozen Space Shuttles. This is the ultimate kick if we can figure out a...

Meteorites a Key to Habitability?

by Paul Gilster | Jun 2, 2009 | Astrobiology and SETI | 5 Comments

You wouldn't think life on a planet being bombarded by debris in the early days of its solar system would have much chance for survival. Indeed, the prospect of being pummeled for millions of years in the Late Heavy Bombardment has led to scenarios in which life started, was extinguished, and re-started on this planet, the idea being that the massive cratering we see on objects like the moon was also being enacted here. But maybe we can make a virtue of necessity and consider what all those incoming objects might have done long-term to improve the atmospheres of the planets they landed on. So goes the thinking in a new study that examines the composition of ancient meteorites to see what they would do when heated to temperatures like those caused by a fiery descent to Earth. Using a method called pyrolysis-FTIR, in which the meteorite fragments were quickly heated (at a remarkable 20,000 degrees Celsius per second), the team measured the carbon dioxide and water vapor released. It...

Millisecond Pulsars for Starship Navigation

by Paul Gilster | Jun 1, 2009 | Communications and Navigation | 19 Comments

If we can use GPS satellites to find out where we are on Earth, why not turn to the same principle for navigation in space? The idea has a certain currency -- I remember running into it in John Mauldin's mammoth (and hard to find) Prospects for Interstellar Travel (AIAA/Univelt, 1992) some years back. But it was only a note in Mauldin's 'astrogation' chapter, which also discussed 'marker' stars like Rigel (Beta Orionis) and Antares (Alpha Scorpii) and detailed the problems deep space navigators would face. The European Space Agency's Ariadna initiative studied pulsar navigation relying on millisecond pulsars, rotating neutron stars that spin faster than 40 revolutions per second. The pitch here is that pulsars that fit this description are old and thus quite regular in their rotation. Their pulses, in other words, can be used as exquisitely accurate timing mechanisms. You can have a look at ESA's "Feasibility study for a spacecraft navigation system relying on pulsar timing...

Astrometry Bags a ‘Cold Jupiter’

by Paul Gilster | May 29, 2009 | Exoplanetary Science | 29 Comments

We're now up to 347 detected exoplanets around 293 stars. The latest find turns out to be intriguing on several counts. VB 10 is a red dwarf about 20 light years away in the constellation Aquila. Its newly detected planet is a gas giant with a mass six times that of Jupiter, a 'cold Jupiter' not so different from our own. Interestingly, although the star is considerably more massive, both planet and star should have roughly the same diameter. Image: This artist's diagram compares our solar system (below) to the VB 10 star system. Astronomers successfully used the astrometry planet-hunting method for the first time to discover a gas planet, called VB 10b, around a very tiny star, VB 10. All of the bodies in this diagram are shown in circular insets at the same relative scales. Astrometry involves measuring the wobble of a star on the sky, caused by an unseen planet yanking it back and forth. Because the VB 10b planet is so big relative to its star, it really tugs the star around. The...

Radio Supernovae and the ATA

by Paul Gilster | May 28, 2009 | Deep Sky Astronomy & Telescopes | 6 Comments

We think of the Allen Telescope Array, currently comprising only 42 of the 350 radio dishes planned, as a SETI instrument, capable of digging faint signals out of a wider field of stars than ever before. But the ATA is also engaged in an astrophysical survey of the sky at radio wavelengths, one that will look for radio bursts from supernovae. A glimpse of what it is looking for has just been reported in M82, a small irregular galaxy about twelve million light years from Earth. We're talking about a so-called 'radio supernova,' an exploding star undetectable by optical or X-ray telescopes. The new object is the brightest supernova seen in radio wavelengths in the last twenty years, and one of only a few dozen of its kind observed so far. And while the ATA will help us locate future radio objects of its kind, this one was found with the Very Large Array in New Mexico, and later confirmed through the NRAO's Very Long Baseline Array. Image (click to enlarge): Zooming into the center of...

Maps of an Alien Earth

by Paul Gilster | May 27, 2009 | Exoplanetary Science | 7 Comments

Anyone who thought the Deep Impact mission was over when the spacecraft drove an impactor into comet Tempel 1 some four years ago has been given a lesson in the strategy of extended missions. Now heading for a flyby of comet Hartley 2 (late in 2010), Deep Impact is also doing yeoman work in the study of extrasolar planets. That phase of the mission is called Extrasolar Planet Observations and Characterization (EPOCh), but the spacecraft housing both investigations is now referred to as EPOXI. If the acronyms can be confusing, the latest news from EPOXI is straightforward, and encouraging. A paper slated for summer publication in the Astrophysical Journal reports on the spacecraft's observations of our own planet, made in 2008 when it was between 17 and 33 million miles from Earth. The idea was to tune up our capabilities at observing distant planets, using spectral information to map the distribution of continents and oceans. EPOXI's High Resolution Imager thus set up a trial of...

Growing the Interstellar Probe

by Paul Gilster | May 26, 2009 | Autonomy and Robotics | 20 Comments

Centauri Dreams reader Brian Koester passed along a link to a provocative video last month that spurs thoughts about the nature of interstellar probes. The video is a TED talk delivered by Paul Rothemund in 2007. For those not familiar with it, TED stands for Technology, Entertainment, Design, a conference that began in 1984 and now brings together interesting scientific figures whose challenge is to give the best talk they can on their specialty within the span of eighteen minutes. I've been pondering Rothemund's talk for some time. You can call this Caltech bioengineer a 'DNA origamist,' meaning that he is exploring ways to fold DNA into shapes and patterns. As becomes clear in his presentation, folding DNA into 'smiley' faces or maps has a certain wow factor, but once you get past the initial wonder of working at this level, you begin to appreciate how research in DNA nanotechnology points toward self-assembling devices that can be built at the micro-scale. Molecular Computing to...

Creating Stars in the Laboratory

by Paul Gilster | May 25, 2009 | Advanced Rocketry | 15 Comments

The 192 lasers of the National Ignition Facility at Lawrence Livermore National Laboratory in California can focus 500 trillion watts of power onto a pellet of hydrogen fuel the size of a pencil eraser. With full-scale experiments slated to begin soon, we'll learn much about the feasibility of nuclear fusion on Earth, hoping to extract more energy from the process than goes into making it happen. The forms of hydrogen at play here are deuterium and tritium, which fuse to form helium. Image: All of the energy of NIF's 192 beams is directed inside a gold cylinder called a hohlraum, which is about the size of a dime. A tiny capsule inside the hohlraum contains atoms of deuterium (hydrogen with one neutron) and tritium (hydrogen with two neutrons) that fuel the ignition process. Credit: National Ignition Facility. Inertial confinement fusion using lasers is a different approach than the magnetic confinement method used at the International Thermonuclear Experimental Reactor (ITER),...

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In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).

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