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Hubble’s Woes, JWST’s Promise

by Paul Gilster | Jan 31, 2007 | Deep Sky Astronomy & Telescopes | 8 Comments

With its Wide Field Planetary Camera 2, Near Infrared Camera Multi-Object Spectrograph (NICMOS), and Fine Guidance Sensors still operational, the Hubble Space Telescope isn't exactly blind. But the loss of the Advanced Camera for Surveys would be a serious one, and the bad news is that the next servicing mission, scheduled for mid-2008, probably won't be able to fix the problem. ACS lived out its five year operational life but dazzling vistas like the Ultra Deep Field make us yearn for more. Hubble's other instruments are still doing good science. Recall that the UDF itself is actually made up of images from the ACS and NICMOS, leading Centauri Dreams to believe that many observational programs will go forward after adjusting to the change in instrumentation. As always, we make a virtue of necessity, a phrase first recorded by Chaucer that resonates even now in the realm of deep space exploration. Meanwhile, we receive more positive news from the testing of the James Webb Space...

A Close Eye on Fomalhaut

by Paul Gilster | Jan 30, 2007 | Deep Sky Astronomy & Telescopes | 6 Comments

It took six years to develop the design for the 'microshutters' that will fly aboard the James Webb Space Telescope. They will work with its near infrared spectrograph to screen out light from foreground objects. The advantages are enormous: The Webb telescope will be able to adjust its light mask with exquisite precision, something that previous technologies could not achieve to anywhere near this level of performance. We're talking thousands of tiny shutters -- 62,000 to be exact -- each measuring 100 by 200 microns, arranged in four identical grids. They'll function in front of an eight million-pixel detector, allowing only the light from the specific areas under observation to reach the instrument. Moreover, the new technology greatly widens the efficiency of the instrument in terms of observational time. Says Harvey Moseley (principal investigator for the microshutter at GSFC): "The microshutters provide a conduit for faint light to reach the telescope detectors with very little...

Hot Jupiters: The Metallicity Question

by Paul Gilster | Jan 29, 2007 | Exoplanetary Science | 8 Comments

A globular cluster is a glorious thing. Consider Omega Centauri, a vast city of stars about 15,000 light years from Earth. Clusters like this one are composed of millions of Population II stars, meaning they're among the oldest observed stars and may date back as far as twelve billion years. A result of their early formation is that they remain deficient in metals (in astronomical terms, the elements above hydrogen and helium), making them ideal laboratories for a particular branch of exoplanet studies. Image: This image of Omega Centauri, the brightest and largest globular cluster in the sky, was obtained with the Danish 1.5 m telescope at the ESO La Silla observatory. It shows the central part only; the cluster is actually much larger than the field reproduced here. Credit: European Southern Observatory. A growing assumption about the massive 'hot Jupiters' we've found in our early planet hunting is that their existence depends upon a relatively high metallicity in their host star....

First Views of 21-Lutetia

by Paul Gilster | Jan 27, 2007 | Outer Solar System | 4 Comments

Centauri Dreams' view is that the more we can learn about asteroids, the better. And the interest isn't purely scientific. One day we may have to set about nudging an approaching asteroid so as to prevent a collision with Earth, and if that day comes, we'll need to have a plan in place that depends upon a thorough understanding of these objects and their composition. In the long run, asteroid studies are anything but optional. The European Space Agency's Rosetta mission is filling in some of the gaps enroute to comet 67P Churyumov-Gerasimenko. In its sights are two asteroids -- 2867-Steins and 21-Lutetia -- orbiting between Mars and Jupiter. We'll learn a lot more about both between now and July of 2010, by which time Rosetta will have viewed each at close range. Meanwhile, the spacecraft has taken a first look at 21-Lutetia using the onboard OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) instruments. At the time of its observations, the vehicle was roughly 245...

The Big Questions Explored

by Paul Gilster | Jan 26, 2007 | Culture and Society, Exotic Physics | 1 Comment

Sometimes what we don't know is more interesting than what we do. I'm always confounded when I hear people lay out confident scenarios for the human future, each different from the next, when we're still at a stage where we don't even know what the universe is made of. While we're figuring out dark matter and (even worse) dark energy, we can answer some of the other big questions looked at in this article in Wired. What happens to information in a black hole? What causes gravity? How do entangled particles communicate? Some significant names tackle these questions -- not all cosmological by any means -- in entertaining form.

Toward a Soft Machine

by Paul Gilster | Jan 26, 2007 | Autonomy and Robotics | 3 Comments

When Project Daedalus was being designed back in the 1970s, the members of the British Interplanetary Society who were working on the starship envisioned it being maintained by 'wardens,' robots that would keep crucial systems functional over the 50-year mission to Barnard's Star. Invariably, that calls up images of metallic machines, stiff in construction and marked by a certain ponderous clumsiness. True or false, it's a view of robotics that has persisted until relatively recently. But if you're going to do long-term maintenance on a starship, you'd better be more flexible. And that makes a Tufts initiative interesting not just from a space perspective but for applications in medicine, electronics, manufacturing and more. The Biomimetic Technologies for Soft-bodied Robots project aims to produce machines that draw on the model of living cells and tissues. Five Tufts departments will work with a $730,000 grant from the W.M. Keck Foundation to get the job started. Check out what's...

A Cometary Transformation

by Paul Gilster | Jan 25, 2007 | Outer Solar System | 10 Comments

Somehow I missed Mike Brown's recent thoughts on 2003 EL61, the oddly elongated Kuiper Belt object that's as big as Pluto along its longest dimension. Fortunately, the BBC recently covered the story. At the American Astronomical Society meeting in Seattle, Brown (Caltech) had discussed the instability of the object's orbit, pointing out that it is headed for an eventual encounter with Neptune. A possible outcome: Two million years from now, 2003 EL61 may be a comet. "When it becomes a comet," says Brown, "It will be the brightest we will ever see."

First Light for COROT

by Paul Gilster | Jan 25, 2007 | Exoplanetary Science | 3 Comments

The COROT space telescope doesn't start scientific observations until February, but the protective cover of the 30 centimeter instrument has now been opened. So far so good. A preliminary calibration exercise -- using the constellation of the Unicorn near Orion -- delivers data of excellent quality. This news from the European Space Agency should keep exoplanet hunters primed as the search for transiting worlds takes to space. A diagram of COROT's interesting orbit can be found here.

‘Light Science’ Finds Titan Jet Stream

by Paul Gilster | Jan 25, 2007 | Outer Solar System | 2 Comments

When I interviewed the Jet Propulsion Laboratory's James Lesh several years ago, he explained how space scientists could use radio signals to do science. It's the ultimate technique for taking advantage of what's at hand. If your spacecraft is moving behind a planet it's investigating as seen from Earth, the changes to its signal as it disappears behind the disk tell you much about the composition of the planetary atmosphere. "One person's noise," said Lesh, "is another person's signal." Of course, that kind of work isn't limited to radio. Twice on November 14, 2003 Titan passed in front of a star, the events separated by just seven and a half hours. As you would expect, the occultation tracks were different, one visible from the Indian Ocean and southern Africa, the other from the Americas and western Europe. The effects of Titan's atmosphere on the starlight have, in each case, supplied information about the movement of gases around the frigid world. This work required observations...

Tweaking the Past

by Paul Gilster | Jan 24, 2007 | Exotic Physics | 1 Comment

It was Richard Feynman who proposed that particles like positrons -- the antimatter equivalent of the electron -- were actually normal particles traveling backward in time. Feynman would develop the idea with John Wheeler, and it continues to resonate with John Cramer (University of Washington), whose 'transactional' interpretation of quantum mechanics works with particle interactions that depend upon movement forward and backward in time. In December we looked at an experiment Cramer is developing to study this effect, which is best known as retrocausality. So it's nice to see that Patrick Barry's fine article on Cramer's work, and retrocausality in general, is available online from the San Francisco Chronicle. Originally written for New Scientist, the article is thus freed from that magazine's firewall and available for general access. A snippet: While Cramer last week prepared to start a series of experiments leading up to the big test of retrocausality, some researchers expect...

SETI and Its Critics

by Paul Gilster | Jan 24, 2007 | Astrobiology and SETI, Culture and Society | 8 Comments

From the Paramus Post, a story by Bruce Lieberman looks at contrasting views of SETI: On both sides of the SETI debate, scientists acknowledge that what's certain is the limit of what they know. "I personally think that because the origin of life is an extremely difficult process ... even simple life is very rare in the galaxy," Zuckerman said. "But I have no particular claims other than my gut feeling." Shostak has publicly debated Zuckerman on the issue, and he remains confident that future searches will make contact. "I doubt that I would conclude that nobody's out there," he said. "To me that seems like a last-resort option. But that's simply my feeling on the matter. And my feeling on the matter ... actually means nothing because what counts is what you can find. "That's the difference between science and belief." A quick overview of the topic, available here.

A World Lit by Three Suns

by Paul Gilster | Jan 23, 2007 | Exoplanetary Science | 12 Comments

Habitable planets in multiple star systems are one of science fiction's great tropes. Find a second star somewhere in the daylight sky and you know you're not in Kansas anymore. It makes slow going today, but as a kid I was struck with William F. Temple's The Three Suns of Amara (1962), a story whose questionable science and creaky plot was somewhat mitigated by its striking imagery. For Amara managed to weave its orbit through a triple star system in which each star was a different color. Talk about great visual effects! Image: My battered copy of Temple's The Three Suns of Amara, rescued from a closet. Not the best novel I've ever read, but it did instill a lifelong fascination with habitable planets in multiple star systems. Yesterday we looked at Elisa Quintana's work on habitable planets in binary systems, and while reviewing for that story, I found Temple's Amara again coming to mind. For it turns out we do have five confirmed exoplanets known to orbit one member of a triple...

Binary Stars and Terrestrial Worlds

by Paul Gilster | Jan 22, 2007 | Exoplanetary Science | 12 Comments

The findings about possible terrestrial worlds around the Alpha Centauri stars have become more encouraging than ever. Key work in this regard has been performed by Elisa Quintana and collaborators, who have shown in their simulations that, depending on initial disk inclinations, 3-5 such planets might form around Centauri A and 2-5 around Centauri B. We've already discussed that research and I don't want to linger on Quintana's 2002 paper (reference below) other than to note one interesting comparison. When the same initial disk parameters are placed around a single star like the Sun, the accretion of the planetary disk occurs over a much larger expanse of time. Evidently a stellar companion hastens the process of planetary formation, one billion years in the case of the Sun vs. perhaps 200 million years in the Centauri scenario. Quintana, Jack Lissauer (both at NASA Ames) and team went on from that study to look at planet formation around close binaries. And they've now turned to...

A Quiet Day at the Galactic Core

by Paul Gilster | Jan 20, 2007 | Deep Sky Astronomy & Telescopes | 4 Comments

The mammoth black hole Sagittarius A* isn't the only interesting thing near the center of our galaxy. The European Space Agency's Integral observatory, working with gamma rays, tracks about eighty high-energy sources in the area. About ten of those closest to the galaxy's center had faded when Integral performed a series of observations last April. A mysterious force? Hardly. "All the sources are variable and it was just by accident or sheer luck that they had turned off during that observation," says Erik Kuulkers of ESA's Integral Science Operations Center. Fair enough, and useful for astronomers, who were able to use the sudden quiet to look for still fainter sources, and to set limits on the brightness of the x-ray binaries involved. These consist of two stars orbiting each other, one a normal star, the other a collapsed object -- a white dwarf, neutron star or black hole. The compressed star pulls off gaseous material from its companion, heating it to a million degrees...

Quick Turnaround to Barnard’s Star

by Paul Gilster | Jan 20, 2007 | Culture and Society | 5 Comments

A relativistic trip to Barnard's Star? Those who read French will want to check out the log of such a journey as Philippe Guglielmetti sees it. Traveling at a constant 1g for acceleration and braking, the mission reaches 0.99999 c, travel time twelve years but only three as experienced by the crew. The fictionalized journey plays fast and loose with the star itself, as Adam Crowl notes in a comment below, but the trip is fun even with my rusty French. Have a look.

Seeing an Empty Cosmos

by Paul Gilster | Jan 20, 2007 | Astrobiology and SETI | 12 Comments

Michael Anissimov looks out at a universe devoid of intelligence other than our own. Here's a clip, referring to Frank Tipler's 1980 paper "Extraterrestrial intelligent beings do not exist": It was quite a few years ago when I looked up to the stars, with Dr. Tipler's book in my hand, that I realized he was right - the stars are empty, ready to be harvested and spun into pure energy with the help of gravitational singularity goodness. No aliens, green bug-eyed ones or otherwise, are waiting there to be inconvenienced. And this: Luckily, hypertelescopes may finally put the nail in the coffin of SETI - perhaps 100 years from now. We will be able to see even the simplest of flora, if they exist in large numbers on exoplanets. (Though what we should really be looking for are Dyson spheres or disappearing stars, and as far as we can tell, there are absolutely none.) After we look at a good thousand earth-sized objects and see nothing there but vast, dead wastes, we'll start getting used...

New Horizons Primes for Jupiter

by Paul Gilster | Jan 19, 2007 | Missions, Outer Solar System | 5 Comments

The New Horizons mission may have one primary target, the Pluto/Charon binary at the edge of the Kuiper Belt, but the science along the way should be interesting indeed. Up next in late February is the Jupiter flyby, whose powerful gravity assist will boost New Horizons' velocity past 23 km/s and provide the needed stress tests to put onboard instrumentation through its paces and refine the methods for data collection. But there's plenty to do in Jupiter space beyond setting up for the 2015 Pluto encounter. For one thing, Jupiter's magnetosphere extends far beyond the planet itself, and New Horizons will be the first probe to move along the 'tail' of this stream of charged particles. These studies will complement the earlier magnetosphere work of Cassini and Galileo. All told, 700 observations of Jupiter and the Galilean moons are planned, with data gathering from January through June, including looks at the ring system and a close-up look at the 'Little Red Spot' the storm that's...

Of Fermi and Slow Probes

by Paul Gilster | Jan 18, 2007 | Astrobiology and SETI | 18 Comments

Some day alien civilizations may pick up television or radio signals from Earth. But does this mean they're likely to visit us? Danish researcher Rasmus Bjørk (Niels Bohr Institute, Copenhagen) doubts it. "Even then, unless they can develop an exotic form of transport that gets them across the galaxy in two weeks it's still going to take millions of years to find us," says Bjørk in an article in The Guardian. "There are so many stars in the galaxy that probably life could exist elsewhere, but will we ever get in contact with them? Not in our lifetime." Bjørk is in the news because he set up a computer simulation to investigate how long it would take to explore the galaxy. Suppose we build eight probes which, along the way, send out eight more mini-probes, all headed for different stars that are likely to have life. Bjørk's plan is to search only within the galactic habitable zone, to use flyby probes only, and to fan out the spacecraft at one tenth the speed of light. The aim is to...

Deflating Scientific Prose

by Paul Gilster | Jan 18, 2007 | Culture and Society | 3 Comments

What's wrong with scientific papers? Ask physicist and science fiction author Gregory Benford, who tackles the question in a wonderful pastiche for COSMOS. "The sad truth is that hardly anybody ever reads a paper all the way through," Benford writes. "A study by a British physics journal showed that the average number who get through the whole paper was 0.5 - and that included the author! Apparently, most scientists can't bear to reread their own work." Benford's 'study' appears under the title "How to write an awesome scientific paper." Using the nom de guerre Bea Realist, he skewers over-inflated prose and bloated egos without mercy. A sample, touching on the awful overuse of the passive voice: The scientist is, by his reliance on the passive voice, hobbled, leading to sentences like this one, in which the subject, a lumpy noun, is acted upon by pallid adjectives and wan verbs, all without ever saying exactly who the action is done by, so that the sentences get longer and longer as...

‘Cosmic Search’ Available Online

by Paul Gilster | Jan 17, 2007 | Astrobiology and SETI | 3 Comments

It's a pleasure to see that Cosmic Search is now accessible on the Internet. Appearing first in 1979, this magazine devoted solely to SETI was well ahead of its time, trying to generate interest in a popular audience that had not yet become familiar with the concepts driving the search for life in the universe. In those days long before SETI@Home, I learned about Cosmic Search through the Society of Amateur Radio Astronomers, a group I had joined in the mistaken belief that I had could create my own receiving station and do interesting science. That hope was never realized, a victim of my clumsiness with hardware, and I contented myself with reading and learning. Cosmic Search was a true gift, covering the range of SETI investigations and stuffed with reading from the likes of Philip Morrison, Frank Drake, Ronald Bracewell and many other familiar names. Go to the site, where you can scroll through the listings and see for yourself how SETI looked 25 years ago. Cosmic Search will...

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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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