Archives

JPL Releases Iapetus Flyby Map

by Paul Gilster | Dec 31, 2004 | Outer Solar System | 0 Comments

The dark terrain of the Cassini Regio on Iapetus will be the imaging target of the Cassini Saturn orbiter as it whisks past the moon at 2 kilometers per second later today. The Jet Propulsion Laboratory has released this map of the image coverage area. The regions Cassini will view at different imaging scales are shown within colored lines. These images were taken by Voyager in 1981; expect Cassini to deliver much better resolution, not only because of its superior optics, but also because of distance; Voyager passed Iapetus at over half a million miles, while Cassini will close to 76,700 miles (123,400 kilometers).

SETI Institute’s Shostak on the Allen Telescope Array

by Paul Gilster | Dec 31, 2004 | Astrobiology and SETI | 1 Comment

In The New and Improved SETI, the SETI Institute's Seth Shostak weighs in on the Allen Telescope Array, the radio telescope installation that should give a boost to the SETI search as well as offering key research tools to more conventional astronomy. Shostak lists three advantages the ATA will offer SETI researchers, perhaps the most important being the array's ability to make maps of the sky. "In other words," says Shostak, "it's like a radio camera, producing images." Here's his explanation of one ATA advantage: ...the ability to break up a large field of view into small (radio) pixels is also good for the SETI crowd. Consider this: you're a radio astronomer, and your day job is mapping stuff like the Andromeda galaxy. You want your radio pixels to be in a regular, row-and-column matrix, like the members of a marching band. It's a pixel arrangement similar to what your digital camera's CCD has. Fine. But for SETI purposes, you could spread the pixels around a bit, like a few...

Iapetus Flyby Next for Cassini

by Paul Gilster | Dec 30, 2004 | Outer Solar System | 0 Comments

Cassini's post-Huygens separation maneuver occurred without incident on December 27. The course change was needed both to prevent Cassini from following the free-falling Huygens probe into Titan's atmosphere and to set up the required positioning for communications between Cassini and Huygens during the latter's atmospheric entry and descent. Cassini will make a close pass of Iapetus on December 31, and it should be worth watching. Iapetus (pronounced eye-APP-eh-tuss) is the third-largest of Saturn's moons, and it has already gained notoriety because of contrasts in its surface; one side is almost snow-bright, the other dark as tar. This has led to speculation that the surface is undergoing continual resurfacing due to processes that have yet to be identified. Above: Images obtained using ultraviolet (centered at 338 nanometers), green (568 nanometers) and infrared (930 nanometers) filters were combined to produce the enhanced color views at left and center; the image at the right...

New Telescope Should Boost SETI Search

by Paul Gilster | Dec 29, 2004 | Astrobiology and SETI | 0 Comments

290 miles northeast of San Francisco, the University of California at Berkeley and the SETI Institute are building an observatory for galactic and extragalactic radio astronomy at Hat Creek. The Paul Allen Telescope Array (ATA 32), named after Microsoft co-founder Paul Allen, who is a major donor for the project, is to consist of 350 networked 6.1-meter radio dishes spread out along 2.6 acres on the property. In addition to breakthrough radio astronomy, ATA 32 will enable the most comprehensive search for intelligent extraterrestrial signals (SETI) ever attempted. According to this Lab Note by David Pescovitz at Berkeley's College of Engineering , the Allen Telescope Array will speed up the SETI search by a factor of 100. Significantly, the system is designed so that astronomers can do other radio astronomy while the SETI search proceeds. Pescovitz quotes William "Jack" Welch, a UC Berkeley professor of electrical engineering and astronomy who holds UC Berkeley's first Chair in the...

Near-Earth Asteroid No Longer a Threat

by Paul Gilster | Dec 28, 2004 | Asteroid and Comet Deflection, Outer Solar System | 0 Comments

The possibility that a near-Earth asteroid might strike the planet in 2029 has now been ruled out. Asteroid 2004 MN4 had attained press prominence when it emerged that the 400 meter object would pass near the Earth on April 13, 2029, with the odds on impact rising to 1 in 300. That alone made for the kind of story the media love to flog, but the reality all along was that new data about the asteroid's orbit would probably rule out the possibility of impact. And that is just what has happened, thanks to the work of Jeff Larsen and Anne Descour of the Spacewatch Observatory near Tucson, Arizona. By studying archival images of the object, they were able to extend the observational time available to scientists, improving knowledge of the orbit of 2004 MN4 enough to fix its position in space in 2029. The final position is shown in the diagram, with alternate positions ranging through the white line that intersects the projected orbit of the asteroid. It's a close call, but not a...

Image Captures Departing Huygens Probe

by Paul Gilster | Dec 27, 2004 | Outer Solar System | 0 Comments

The Huygens probe, captured in the photograph below as it departs from the Cassini Saturn orbiter, is now on course for its January 14th descent into Titan's atmosphere. Look for the probe in the upper right quadrant of the image. Huygens' separation from Cassini was achieved by firing explosive bolts; the probe was then pushed away by springs and rollers at roughly one foot per second. Image: The Cassini spacecraft snapped this image of the European Space Agency's Huygens probe about 12 hours after its release from the orbiter. The probe successfully detached from Cassini on Dec. 24, 2004, and is on course for its January 14 encounter with Titan. Credit: NASA/JPL. The journey to Titan's surface should be quite a ride. According to this European Space Agency release, the probe will enter the atmosphere on Titan's day side over its southern hemisphere. After the main parachute deploys, the probe will extend its instrument booms and begin collecting data about the moon's atmosphere....

A Thought for the Holidays

by Paul Gilster | Dec 25, 2004 | Culture and Society | 0 Comments

Huygens is now safely on its way. More on this, and on Cassini's post-separation course correction, next week. Until then, best wishes for the holidays, along with a thought from Arthur C. Clarke's Interplanetary Flight: An Introduction to Astronautics (London: Temple Press Limited, 1960): There is no way back into the past; the choice, as Wells once said, is the universe--or nothing. Though men and civilizations may yearn for rest, for the dream of the lotus-eaters, that is a desire that merges imperceptibly into death. The challenge of the great spaces between the worlds is a stupendous one; but if we fail to meet it, the story of our race will be drawing to its close.

Huygens Poised for Separation

by Paul Gilster | Dec 24, 2004 | Outer Solar System | 0 Comments

The Huygens probe separation from the Cassini Saturn orbiter is scheduled to occur late this evening; according to this JPL press release, NASA expects a confirmation of the maneuver around 11 PM EST. The probe, which has been attached to Cassini for the seven-year trip to Saturn, has remained in sleep mode except for periodic 'awakenings' every six months to test its instruments. This evening, Huygens will be pushed away from the orbiter by tension-loaded springs and will begin its solo journey toward Titan, which it is expected to reach on January 14. Both Huygens and Cassini are at this point on an impact trajectory with Titan, to ensure the accuracy of the probe's arrival at the moon. On December 27, Cassini will change its course, putting it into proper position for radio communications during the probe's descent. The best source for Huygens information is either ESA's Cassini-Huygens page or NASA's Cassini page. The Cassini imaging team page is also well worth checking. While...

Understanding Massive Terrestrial Worlds Around Other Stars

by Paul Gilster | Dec 24, 2004 | Exoplanetary Science | 0 Comments

Diana Valencia, a graduate student at Harvard, has been working with professor of geophysics Richard O'Connell in a study of the possible internal structure of large terrestrial planets around other stars. Their presentation "Internal Structure and Scaling Laws of Massive Terrestrial Planets" was given at the American Geophysical Union's fall meeting. From the abstract: "The focus of this study is to calculate the internal structure of massive terrestrial planets starting from the knowledge acquired on the Earth and other solar system planets. With the use of equations of state for the Earth and physical laws we obtain radial structure profiles of mass, pressure and density, including all major phase changes for massive Earth-like planets." Why is this work important? Because the first mission likely to detect a terrestrial-type planet is Kepler, scheduled for launch in 2006. The spacecraft will attempt to detect such planets by watching for their transit across a distant stellar...

New Camera Could Detect Red Dwarfs Closer than Centauri

by Paul Gilster | Dec 23, 2004 | Deep Sky Astronomy & Telescopes | 0 Comments

The UK's new Wide Field Camera (WFCAM) has just begun operations at the United Kingdom Infrared Telescope site in Hawaii. WFCAM is designed to survey huge swathes of the sky at infrared (heat radiation) wavelengths, and should be able to work with deep sky objects as well as close brown dwarfs and other stars that, although relatively nearby, may have eluded detection. The 'survey' part of its job description means WFCAM is designed for a large field of view; no other infrared camera now operating can equal its range. The early results are spectacular. The two images shown here are among the earliest made by WFCAM. They focus on the area of intense star formation in the constellation Orion, some 1500 light years from Earth. To give you an idea of this telescope's range, the full images it made of this region are 3600 times larger than Hubble's infrared camera. By varying the type of infrared filters, the new camera shows thousands of young stars that would ordinarily be hidden by gas...

Life-Bearing Planets in the Interstellar Dark?

by Paul Gilster | Dec 22, 2004 | Exoplanetary Science | 2 Comments

David J. Stevenson, who is George Van Osdol Professor of Planetary Science at CalTech, has an entertaining way with titles. The average scientific paper has a title whose tone is dry, direct and frequently off-putting. Stevenson gives us these, as any scientist must, but give him the chance and he produces the Swiftian "A Modest Proposal: Mission to Earth's Core," which ran in Nature in 2003 (available here). He has also written, fascinatingly, on the possibilities of oceans on worlds other than Europa; thus his 1999 essay "An Ocean in Callisto?" (The Planetary Report Vol. 19 No 3, pp. 7-11), and "An Ocean in Uranus?" (The Planetary Report Vol. 6 No 16, 1986). At the recent American Geophysical Union meeting, Stevenson produced the ultimate in what we writers call the 'omniscient viewpoint' by presenting "How to Build a Planetary System." So how do you build a planetary system? It turns out that we know surprisingly few answers. Stevenson argues that while such systems are common (at...

Saturnian Moons Continue to Surprise Scientists

by Paul Gilster | Dec 21, 2004 | Outer Solar System | 0 Comments

Cassini's most interesting view of Titan's atmosphere to date is shown here, highlighting what appears to be layer after layer of haze. The image is in the ultraviolet and taken from Titan's night side; the haze layers extend several hundred kilometers above the surface. The region shown here is in Titan's equatorial region, about 10 degrees south latitude. A nice wrap-up of Cassini data from both Titan and Dione, as presented at the American Geophysical Union's fall meeting in San Francisco, can be found on this JPL page. Especially noteworthy is the peculiar, braided character of the fractures on Dione's surface, where the terrain consists of ice cliffs apparently created by tectonic forces. "This is one of the most surprising results so far. It just wasn't what we expected," said Dr. Carolyn Porco, Cassini imaging team leader (Space Science Institute, Boulder, CO). We are now just three days away from the separation of the Huygens Titan probe from the Cassini orbiter, with descent...

Hunting Antimatter High Above Antarctica

by Paul Gilster | Dec 20, 2004 | Antimatter | 0 Comments

Other than high-energy particle accelerators, where on Earth would you look for antimatter? The answer seems to be high above Antarctica. A team of scientists led by Akira Yamamoto of Japan's High Energy Accelerator Research Organization (KEK) is actively hunting antimatter that may be striking the Earth from space. The detector: an instrument carried by a 40-million cubic foot balloon that is circling the South Pole at an altitude of 39 kilometers (24 miles). If successful, the team will learn a good deal about antimatter and may prove the existence of so-called Hawking radiation, low-energy antiprotons created by ancient black holes from the Big Bang era. Called BESS-Polar (Balloon-borne Experiment with a Superconducting Spectrometer), the experiment is a collaborative effort that unites KEK and various Japanese agencies including the Japan Aerospace Exploration Agency with NASA. BESS has been tested in Canada and used to study cosmic rays; it also collected a small number of...

A Thought for the Weekend

by Paul Gilster | Dec 18, 2004 | Culture and Society | 0 Comments

"We hesitate about where to go from here in space. Yet our delay in exploiting this window of opportunity could close off choices for our descendants if the no-growth paradigm--or a failure of nerve--should come to dominate the industrial nations... Because of our technologies, and the scales of our political and economic organizations, we now have the option of taking a conscious evolutionary step, expanding the presence and influence of humanity beyond the biosphere that evolved us--and possibly beyond the limits that otherwise would constrain our future... Our generation is the first to have this choice. It may be up to us to prove that intelligence armed with technology has long-term survival value." -- Michael Michaud in Life in the Universe (AAAS Selected Symposium 31, 1979). Found in the online repository Space Quotes to Ponder.

Aerocapture: A Spectacular, Flaming Arrival

by Paul Gilster | Dec 17, 2004 | Missions | 0 Comments

The nuclear-electric mission to Neptune discussed here on the 14th is one of two now being studied by NASA. The other is powered by chemical rockets and, like Cassini, would use gravity assists to reach Neptune in considerably less time. Its team, led by Andrew Ingersoll of the California Institute of Technology, is working on a design that, like University of Idaho professor David Atkinson's nuclear-electric mission, will be submitted to NASA in mid-2005. A faster mission has many advantages, but a major question arises: how do you stop when you get there? Unlike Voyager, the Neptune missions are to be capable of orbiting the planet and dispatching probes to both it and its largest moon, Triton. One answer Ingersoll's team is studying is aerocapture, which uses the destination planet's atmosphere to alter the spacecraft's trajectory, putting it into orbit after a single pass. If this sounds familiar, you may recall the aerocapture maneuver in the film 2010, a spectacular, flaming...

Digital Wizardry Captures the Tarantula Nebula

by Paul Gilster | Dec 16, 2004 | Deep Sky Astronomy & Telescopes | 0 Comments

Back when I was a kid gawking at images from the Palomar telescope, it seemed that the only way to see farther and better was to build bigger mirrors. We've learned how to do that, of course, but new techniques from adaptive optics to space-borne coronagraphs have made it possible to see things never before revealed. The latest weapon in the astronomers' arsenal is to me the most fascinating; it's the use of computers to combine imagery and tease out new information. The National Virtual Observatory is a case in point, creating the tools needed to maintain interoperating databases. "In a few years it will be easier to "dial-up" a part of the sky than wait many months to access a telescope," according to the NVO's Web site. And now we've got this remarkable image of 30 Doradus, the Tarantula Nebula. 30 Doradus is located in the Large Magellanic Cloud some 170,000 light years from Earth. A small, irregular galaxy that orbits the Milky Way, the LMC seems to be a region of active star...

Remembering “Out Around Rigel”

by Paul Gilster | Dec 15, 2004 | Culture and Society | 4 Comments

Every technology appears in a context, meaning there is a cultural dimension to our creations that will shape and, in turn, be shaped by them. Centauri Dreams occasionally looks at stories, novels and films that have shaped our idea of interstellar flight. Today it's "Out Around Rigel," by Robert H. Wilson, which ran in the December, 1931 issue of Astounding Stories. To my knowledge, Wilson published only one science fiction story, but in its day it was a bombshell. Wilson's tale is simple enough: two adventurers named Garth and Dunal set out from their home on a terraformed Moon of the future to travel to the star Rigel. Garth's ship is the ultimate in new tech; he boasts that with it, they can "...go in a year to the end of the universe. But, for a starter, how about a thousand light-years around Rigel in six months?" Taking the bait, a skeptical Dunal goes onboard even as he questions Garth's science, pointing out that Einsteinian relativity makes it clear nothing can go faster...

Terrestrial Worlds in the Alpha Centauri System?

by Paul Gilster | Dec 14, 2004 | Exoplanetary Science | 1 Comment

More than half of all main sequence stars occur in multiple star systems, and we've already found 19 planets in such systems (Tau Bootis and 55 Rho Cancri are examples). But most of our models of planetary formation have been based upon single stars. Are planets common in double star systems? The answer has huge implications for the number of possible planets, and it's a fascinating issue because the the nearest stars, the Alpha Centauri triple star system, are now considered capable of sustaining planets. Paul Wiegert and Matt Holman showed in 1997 that stable orbits can exist within 3 AU of Alpha Centauri A or B, and they calculated a habitable zone around Centauri A of 1.2 to 1.3 AU, with a zone around Centauri B of 0.73 to 0.74 AU. Planets at Jupiter-like distances seem to be ruled out around Centauri because of the disruptive effects of the two primary stars; after all, Centauri A and B sometimes close to within 10 AU, roughly the distance of Saturn from the Sun. The red dwarf...

A Nuclear-Powered Neptune Orbiter

by Paul Gilster | Dec 12, 2004 | Outer Solar System | 0 Comments

The outer planets, worthy science targets in their own right, could also be considered something of a dry run for a true interstellar probe. And now details of a nuclear-powered mission to Neptune are beginning to emerge; they're coming out of a 12-month planning study funded by NASA and led by Boeing Satellite Systems. Particularly intriguing about Neptune is its moon Triton, which many scientists now believe to be a Kuiper Belt object, a planetoid not formed by Neptunian debris but captured long ago by the planet's gravity. A key part of the mission will be to deploy landers to Triton's surface. A December 17 session at the American Geophysical Union fall meeting will be another shakedown of the concept, which the Neptune team has been fine-tuning at various conferences (and how I missed this one in Centauri Dreams' earlier story on the AGU is beyond me). The session is "A Neptune/Triton Vision Mission Using Nuclear Electric Propulsion." Image: This picture of Neptune was produced...

A Quote for the Weekend

by Paul Gilster | Dec 11, 2004 | Culture and Society | 0 Comments

"Future historians will give a few paragraphs to the Saturn rockets that took us to the Moon, the shuttle that conquered Low Earth Orbit, and the aerospace plane, but they are likely to spend much more time looking at the underlying principles on which their own civilization was founded. They will know that physical technologies are the vessels for the exploration that takes place in human societies, but are not the essence of the transformations that they engender." Frank White, from The Overview Effect: Space Exploration and Human Evolution (Boston: Houghton Mifflin, 1987), p. 161.

« Older Entries

Charter

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).

Now Reading

On Comments

If you'd like to submit a comment for possible publication on Centauri Dreams, I will be glad to consider it. The primary criterion is that comments contribute meaningfully to the debate. Among other criteria for selection: Comments must be on topic, directly related to the post in question, must use appropriate language, and must not be abusive to others. Civility counts. In addition, a valid email address is required for a comment to be considered. Centauri Dreams is emphatically not a soapbox for political or religious views submitted by individuals or organizations. A long form of the policy can be viewed on the Administrative page. The short form is this: If your comment is not on topic and respectful to others, I'm probably not going to run it.

Follow by E-Mail

Advanced Propulsion Research