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The Epsilon Eridani Factor

by Paul Gilster | Jun 17, 2010 | Missions | 25 Comments

When I was a kid, interstellar destinations were sharply defined. It seemed obvious that you didn't even consider Alpha Centauri, because a double-star primary system surely wouldn't allow stable planetary orbits. So you looked around for single stars. Moreover, these should be stars a lot like the Sun, so that when Frank Drake began SETI with Project Ozma, it made all the sense in the world to focus on Tau Ceti and Epsilon Eridani. Both were similar enough to our own star to suggest that they would have planets, and maybe one like ours. For that matter, we had no idea in those distant days whether the Sun was a statistical fluke in having planets or simply a garden-variety star with a system that was all but inevitable. These days we keep finding interesting planets, but so far (other than perhaps in the Gliese 581 system) we haven't found anything enough like the Earth to consider any nearby system an obvious target for an interstellar probe. All that may change, and swiftly, when...

Views of IKAROS (and a Memory)

by Paul Gilster | Jun 16, 2010 | Sail Concepts | 7 Comments

This is what a solar sail looks like in space. The images below were taken by a camera flown aboard the IKAROS mission and then separated from it using a spring, according to the Japan Aerospace Exploration Agency (JAXA). These pictures (and you can find several more here) take me back to my first reading of Cordwainer Smith's 'The Lady Who Sailed the Soul,' in which a far future sail mission involving a sail tens of thousands of kilometers across plays against the tangled relationship of two lives (full text here). IKAROS may be far smaller, but if seeing a deployed sail in space doesn't fire the imagination, what will? A brief snippet from the story: The first sailors had gone out almost a hundred years before. They had started with small sails not over two thousand miles square. Gradually the size of the sails increased. The technique of adiabatic packing and the carrying of passengers in individual pods reduced the damage done to the human cargo. It was great news when a sailor...

750 Planetary Candidates from Kepler

by Paul Gilster | Jun 15, 2010 | Exoplanetary Science | 36 Comments

The release of the first 43 days of Kepler data has demonstrated just how powerful a planet-hunting technology we've put into space. Listen to principal investigator William Borucki (NASA Ames) in a video released yesterday by NASA television: "We're releasing data on 156,000 stars that we've been monitoring with the Kepler mission for 43 days, the first dataset. In these data are some 750 planetary candidates. Some of those are actual planets, some are false positives. Our science team is looking at 400 of those candidates with ground-based telescopes, to figure out which are planets, which aren't." Borucki assumes about fifty percent of the candidates will be false positives, eclipsing binary stars, starspots, or other misleading signals. Now it's in the hands of ground-based telescopes in the Canary Islands, Texas, Arizona and Hawaii to comb through these findings to make the call. The team is also releasing the data for the remaining 350 candidates to the world community of...

CoRoT & Hayabusa: Starting the Week Right

by Paul Gilster | Jun 14, 2010 | Exoplanetary Science, Outer Solar System | 10 Comments

If we ended last week on a high note with the successful deployment of the IKAROS sail, this week started equally well with the return of JAXA's Hayabusa spacecraft, whose re-entry capsule has now been recovered from the Australian desert and is intact. We'll learn once it gets back to Japan how much material from asteroid Itokawa it was able to acquire. But what an exciting finish to this mission, and what a accomplishment by JAXA to survive battery failures, communications problems, engine issues and more and bring this mission home. [youtube gfYA4f-AIL0 500 375] The canister return is the fruit of a seven year journey that saw Hayabusa touch down on Itokawa back in 2005, and although the many glitches caused a three year delay in its return, Hayabusa may well offer us at least trace amounts of material from the asteroid, valuable in helping us understand not only the asteroid itself but also the early history of the solar system. We have so few instances of material recovered from...

Oort Finding: Many Comets From Other Stars

by Paul Gilster | Jun 11, 2010 | Deep Sky Astronomy & Telescopes | 15 Comments

Here's something to put the cap on a scintillating week in space science. It's from Hal Levison (SwRI), who has led an international team in computer simulations focusing on our Sun's earliest days. It turns out that our older assumption that the Oort cloud of comets surrounding the Sun came from the Sun's protoplanetary disk may not be accurate. Yes, our system produced comets, but not enough to account for the Oort's entire population, which swarms in a vast sphere that extends half the distance to Alpha Centauri. Says Levison: "If we assume that the Sun's observed proto-planetary disk can be used to estimate the indigenous population of the Oort cloud, we can conclude that more than 90 percent of the observed Oort cloud comets have an extra-solar origin." Image: Comet McNaught, possibly an interloper from another star, according to recent work. Credit: Stéphane Guisard. The process works like this: We believe the Sun formed in a cluster containing hundreds of closely packed...

IKAROS Deployment in Translation

by Paul Gilster | Jun 11, 2010 | Sail Concepts | 4 Comments

For those of you interested in the key IKAROS post describing the final deployment of the sail, Lionel Ward has been so kind as to translate it in context. I'm leaving out the actual photographs, which you can see via the links posted in my previous IKAROS coverage -- and also here in context -- but here is the text from JAXA: ------- 2010?6?11?[??]? A world first! Solar Powered Electrical Sail deployment and power generation is successful! ????????????????&????? On June 8th the finalization of the primary deployment was executed, and on June 9th the secondary deployment was executed. 6?8?????????????????6?9?????????????? IKAROS’ state at the end of the primary is detailed over on the Ikaros blog. ???????????????????????????? Upon sending the command to initiate secondary deployment, a state of nervousness persisted in the command center during the 46 second propagation delay (the separation from earth is 7.4 million km!) until the initial data could be seen. That deployment had...

IKAROS Deployment Photos Arriving

by Paul Gilster | Jun 11, 2010 | Sail Concepts | 1 Comment

IKAROS now appears to be fully deployed and generating power from its photovoltaic cells. The IKAROS blog even has a photo of the cake with which the sail team celebrated the success, but you'll also want to go to this IKAROS page for a look at further imagery, one of which is the photo shown below. The page has four similar photographs from different cameras aboard the spacecraft, and if I'm reading this right, more photos will be posted here as they become available. JAXA has also made available this news release about the deployment. Lionel Ward, our Japanese translator extraordinaire, will be sending translations of the IKAROS blog postings and recent tweets from JAXA later today, and I'll post these as a way of archiving the information here. This afternoon (1800 or so UTC) I'll have today's regular Centauri Dreams post up, but I wanted to share this image and give you the pointer for more as soon as possible. What an achievement this mission has turned out to be even this early...

? Pictoris b: A New Planet and Its Implications

by Paul Gilster | Jun 10, 2010 | Exoplanetary Science | 2 Comments

One of the problems with determining how planets form is the nature of the dusty gas-rich disks that surround their stars. We're learning as we study these things that the disks around young stars disperse quickly in astronomical terms, within several million years. Thus finding a massive planet around a young star like Beta Pictoris is noteworthy. It demonstrates that such planets can form in short-order. What's doubly fascinating about the new find is that this planet was discovered by direct imaging techniques, and that it is as close to its star as Saturn is to ours. Have a look at the imagery below, made using the European Southern Observatory's Very Large Telescope and an adaptive optics instrument that removes atmospheric blurring and other effects. It's a composite showing the faint source in the 2003 image and contrasting it with the motion of the object as seen in the autumn of 2009. The object can be seen to have moved to the other side of the disk. As we only have direct...

Holding for Later Today

by Paul Gilster | Jun 10, 2010 | Administrative | 4 Comments

Update: As of 1611 UTC, the IKAROS blog is reporting "IKAROS state has been confirmed to be good." More images and data are in the works, but we're not likely to see anything until tomorrow. It's getting late in Japan (2306 JST as I write, or 1406 UTC), and although a JAXA tweet promised new photos for today, the IKAROS blog is still showing the same deployment image we looked at yesterday. More as it becomes available and, naturally, I'm also following the fortunes of Hayabusa, now on final approach to the Woomera Test Range in South Australia. Re-entry is targeted for June 13. Meanwhile, I'm holding on a story (not on IKAROS) that comes off embargo this afternoon and will be posting today's main entry in a few hours.

IKAROS Sail Deployment in Progress

by Paul Gilster | Jun 9, 2010 | Sail Concepts | 5 Comments

Update: The IKAROS blog reports "The operation ended today as planned." That must count as good news for the sail, now 7,480,787 kilometers from Earth, but we still need confirmation that the sail's 'secondary' deployment is now complete. Maybe this is it: Japanese space journalist Mitsunari Kita, who is attending a press conference re the Hayabusa mission, has sent out a tweet (@kitamitsunari) congratulating the IKAROS team on full deployment of the sail (1805 UTC). What extraordinary times these are for the Japan Aerospace Exploration Agency (JAXA). We are in the midst of an interplanetary solar sail mission even as the Hayabusa asteroid explorer prepares for re-entry over Australia, an event that should occur around 1400 UTC on June 13. The Hayabusa craft will release its 16-inch-wide entry capsule some three hours before landing. We've concentrated on IKAROS in these pages, but what a story Hayabusa has been, launched in 2003 to explore the asteroid Itokawa, which it did, but not...

IKAROS Nears Full Deployment Attempt

by Paul Gilster | Jun 8, 2010 | Sail Concepts | 3 Comments

Update: The IKAROS team has not confirmed full deployment of the sail, but does indicate we'll have an update tomorrow. The IKAROS solar sail is partially deployed but the complete deployment was delayed while the mission's engineers tried to figure out why the spacecraft's spin rate has been increasing. JAXA's updates are in Japanese, but the Planetary Society's Emily Lakdawalla seems to be more skilled at untangling Google Translate than I am and has also used a translation from a user on the excellent unmannedspaceflight.com site to come up with IKAROS details. Thus we learn that the sail is currently deployed about five meters. A new update just in from JAXA points to an attempt at full sail deployment just a few hours from now. This video shows the process at work. [youtube 7Mb47w0vB04 500 375] From what JAXA says, there is no danger to the spacecraft from the increased spin rate, but the pause in deployment arose simply because the team wanted to pin down an explanation for the...

Jupiter Impacts Add Up

by Paul Gilster | Jun 6, 2010 | Asteroid and Comet Deflection | 8 Comments

These days we think of Giovanni Cassini in relation to Saturn, for obvious reasons, but the Italian astronomer (1625-1712) did a lot more than discovering the division in the rings of Saturn that would later bear his name. In addition to his studies of the Saturnian moons, Cassini shares credit for the discovery of Jupiter's Great Red Spot, and in conjunction with Jean Richer, made parallax observations of Mars that allowed its distance to be determined in 1672. But back to Jupiter, for in 1686 Cassini reported seeing a dark spot on the planet, one that from his description was roughly the size of the largest impact made by the Comet P/Shoemaker-Levy comet fragments in 1994. We're dealing with crude telescopes and lack of corroborating information with Cassini's observation, but Shoemaker-Levy left us with Hubble imagery when it struck the giant planet after breaking apart into more than twenty pieces enroute. I mention Cassini's early sighting because it's possible he was also...

Complex Reactions on Titan

by Paul Gilster | Jun 4, 2010 | Outer Solar System | 32 Comments

Finding life on Mars would be a huge accomplishment, but finding life on Titan would be a fundamentally different kind of discovery. Martian life might well be related to us because of the exchange of materials between our two worlds, the inevitable result of planetary impacts and the scattering of debris. But Titan is a far more unearthly place than Mars, its chemistry exotic, its climate seemingly beyond the range of any life form we have ever discovered. Life on Titan should be evidence of that 'second genesis' planetary scientists dream of identifying. Image: This artist concept shows a mirror-smooth lake on the surface of the smoggy moon Titan. Cassini scientists have concluded that at least one of the large lakes observed on Saturn's moon Titan contains liquid hydrocarbons, and have positively identified ethane. This result makes Titan the only place in our solar system beyond Earth known to have liquid on its surface. Credit: NASA/JPL. Now we have two papers based on Cassini...

Manned Missions to the Outer System

by Paul Gilster | Jun 3, 2010 | Outer Solar System | 22 Comments

Ralph McNutt's contributions to interstellar mission studies are long-term and ongoing. We've looked at the Innovative Interstellar Explorer concept he has been studying at the Applied Physics Laboratory (Johns Hopkins), but IIE itself rose out of earlier design studies for a spacecraft that would penetrate the heliopause to reach true interstellar space. One possibility for that earlier probe was a 'Sun-diver' maneuver, a close pass by the Sun to gain a gravitational slingshot effect, followed by an additional kick from an onboard booster. The thinking a few years back was to reach 1000 AU in less than fifty years, but Innovative Interstellar Explorer has lost the Sun-diver maneuver and focuses on a more realistic 200 AU, as part of a NASA Vision Mission study that contemplates a gravitational assist at Jupiter and the use of radioisotope electric propulsion. IIE is subject to the same funding constraints as any other mission of this nature but it's well worth perusing its specs on...

A Solitary Astronomer No Longer

by Paul Gilster | Jun 2, 2010 | Deep Sky Astronomy & Telescopes | 7 Comments

Students now getting their degrees in astronomy and even postdocs working in the field have come along at a time when datasets are widely shared. It was not always so, as Alexander Szalay can attest. A professor of physics and astronomy at Johns Hopkins, Szalay was an early player in the Sloan Digital Sky Survey, leading the design of the archive and becoming involved with the statistical tools needed to analyze its holdings. Back in the 1990s, Szalay recalls in the Chronicle of Higher Education (thanks to Regina Oliver for the tip), the astronomy community had no tradition of making data from projects like the SDSS public. In fact, astronomy at the time was a more tightly controlled enterprise. Telescope time, as always, was difficult to get, and no scientist wants critical findings to be claimed by someone else. Szalay remembers that era and the changes that quickly followed: One incident demonstrates the mood at the time. A young astronomer saw a dataset in a published journal and...

LightSail-1 Nears Critical Design Review

by Paul Gilster | Jun 1, 2010 | Sail Concepts | 5 Comments

The crescent Earth is lovely in this ultraviolet photo taken by the Japanese Akatsuki probe, now enroute to Venus. The shot was made at a distance of about 250,000 kilometers and keeps me in mind of the IKAROS solar sail demonstrator, which was launched along with Akatsuki and several other payloads on May 20. It's been tricky keeping up with IKAROS (let's just say my Japanese is not up to speed, and neither is Google Translate), but a 'tweet' from JAXA yesterday said that four cameras aboard the spacecraft had captured images of deployed tip masses, a cause for applause in the IKAROS control room. Photos of that deployment (on May 28) are available on this JAXA site. The sail deployment procedure begins with release of the tip masses and proceeds through stages, as shown below. Image: Deployment procedure for IKAROS. We'll follow IKAROS with great interest as we move toward full sail deployment. Meanwhile, word from Louis Friedman at the Planetary Society is that LightSail-1 is...

vIcarus: Interstellar Mission in Cyberspace

by Paul Gilster | May 31, 2010 | Missions | 7 Comments

One of the most useful technologies the Project Daedalus team lacked when designing its interstellar probe back in the 1970s was the personal computer. Today's effort to re-visit Project Daedalus can draw on the strength of intercontinental networking for fast communications and widespread computer availability to design a probe differently. It's exciting to hear that the Project Icarus team plans vIcarus, a 'virtual' interstellar mission drawing on the completed Icarus design and 'flown' through ongoing computer simulation. Spun out in real time, vIcarus will give designers and the public a chance to follow the mission step by step. Andreas Tziolas (Variance Dynamical Corporation) discussed the idea on the Project Icarus blog recently, noting that over the next few years, the Icarus team will be creating computational models for propulsion, fault repair, communications, flight through the interstellar medium and all the factors impinging upon the behavior and stability of the...

To Join the ‘Galactic Club’

by Paul Gilster | May 28, 2010 | Astrobiology and SETI | 42 Comments

Is there a 'Galactic Club' of civilizations to which our species might one day deserve admission? If so, the club's members are being mighty quiet about their existence. But David Schwartzman (Howard University) thinks it might be out there. In that case, he finds three possible explanations for the 'Great Silence,' our failure to detect any signs of extraterrestrial intelligence in the last fifty years. He rejects the first, the notion that we are alone in the galaxy -- life is, in his view, all but inevitable in the universe, and he's keen on the idea of high levels of intelligence developing on many worlds, as he tells us in this article in Astrobiology Magazine: I have argued that encephalization - larger brain mass in comparison to body mass -- and the potential for technical civilizations are not very rare results of self-organizing biospheres on Earth-like planets around Sun-like stars. Biotically-mediated climatic cooling creates the opportunity for big-brained multicellular...

The Milky Way from Outside

by Paul Gilster | May 27, 2010 | Deep Sky Astronomy & Telescopes | 17 Comments

We sometimes forget the conditions under which great images get made. A few years back, in one of the earliest posts on his systemic site, Greg Laughlin (UC-Santa Cruz) showed the image you see below, a famous shot made by the Hubble telescope of the 'Sombrero Galaxy,' M104. It's obvious why this image is a classic. As Greg notes, "The glow of its halo makes the idea of 100 billion stars seem comprehensible." But look at the follow-up picture, which Greg made to demonstrate his point. While the Hubble image is a long CCD time-exposure to light gathered by a 240 cm mirror, your own eyes would deliver something considerably different. From 300,000 light years, M104 is noticeable only as a dim and lurking shape. You can see the same effect for yourself if you find the Andromeda Galaxy, subtening an angle larger than the full Moon in our skies but as evanescent as smoke when viewed by the naked eye. The dim, fuzzy object is out there if you know where to look, but it's not exactly...

WISE: First Survey Ends in July

by Paul Gilster | May 26, 2010 | Deep Sky Astronomy & Telescopes | 8 Comments

What a glorious image WISE has given us. The Wide-field Infrared Survey Explorer has finished three-quarters of its infrared map of the entire sky, with the final images scheduled for July, after which time the spacecraft will spend three months on a second survey before its solid-hydrogen coolant (needed to keep its infrared detectors chilled) runs out. The public WISE catalog will be released a little over a year from now, but we can already marvel at spectacles like the Heart and Soul nebulae, seen below. Be sure to click on the image, presented at the American Astronomical Society meeting in Miami, to enlarge it and spend some time among the newly forming stars. Image: Located about 6,000 light-years from Earth, the Heart and Soul nebulae form a vast star-forming complex that makes up part of the Perseus spiral arm of our Milky Way galaxy. The nebula to the right is the Heart, designated IC 1805 and named after its resemblance to a human heart. To the left is the Soul nebula,...

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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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