by Paul Gilster | Nov 13, 2007 | Administrative, Culture and Society |
“The Future of the Vision for Space Exploration” is the title of a panel I’ll be moderating tomorrow in Washington DC. In fact, by the time you read this, I should be in transit and looking forward to renewing several good friendships. It’s the first session of the Seed/Schering-Plough Science + Society breakfast series, taking place in the House Energy and Commerce Committee Room on Capitol Hill, the goal being to discuss our future in space for an audience of policymakers and Congressional staffers.
The event’s organizers have lined up quite a panel:
- Louis Friedman, executive director of The Planetary Society and long-term advocate of a sound and far-reaching space policy, with extensive background at JPL and experience on missions ranging from Mariner to Voyager and Galileo.
- Steven Squyres, principal investigator for the science payload on the Mars Exploration Rover project, co-investigator on several other Mars missions including the 2009 Mars Science Laboratory, and member of the imaging team for the Cassini Saturn mission.
- Gregory Matloff, author of The Starflight Handbook (Wiley, 1989) and co-author (with Les Johnson and C Bangs) of Living Off the Land in Space (Copernicus, 2007). Dr. Matloff is a long-time researcher into interstellar issues and author of over one hundred scientific and technical papers.
- Edward Belbruno, the master of ‘chaotic’ orbits that offer spectacular fuel efficiency, as proven in the rescue of the Japanese Hiten lunar mission and in ESA’s SMART-1 mission to the Moon. Dr. Belbruno is author of the recent Fly Me to the Moon (Princeton University Press, 2007).
It will be a quick turnaround — I should be back in 36 hours — but do be aware that it affects posting here. I never travel with a computer (and doubt I would have time to do any editing during the trip anyway), which means that any comments left on Centauri Dreams during travel time may go without moderation for up to a day or so. I’ll get to them as soon as I return. Larry Klaes will have the lead on Wednesday and I’ll be back with a new post of my own the following morning.
by Paul Gilster | Nov 12, 2007 | Deep Sky Astronomy & Telescopes |
We have much to learn about cosmic rays but the basics seem established. They are protons and subatomic particles including the nuclei of atoms like hydrogen, oxygen, carbon, nitrogen or iron. Low-energy cosmic rays are known to come from the Sun and presumably other stars, while medium-energy cosmic rays can be explained through stellar explosions. But there are events so powerful that they dwarf all others. A cosmic ray with an energy of 300 billion billion electron volts was detected in 1991, the highest levels ever associated with the phenomena.
Where do such ultra-high energy particles come from? They’re 100 million times more energetic than anything we can produce with particle accelerators. Fortunately, the fact that they travel more or less in a straight line, not being deflected as strongly as their lower-energy cousins, makes observations of their origin possible. Now the more than 370 scientists working with the Pierre Auger Observatory in Argentina think they have found the source: The centers of active galaxies with supermassive black holes, known as Active Galactic Nuclei (AGN).
The idea makes intuitive sense even if the correlations the scientists have found need to be weighed against data from other groups in order to be confirmed (and it must be said that we still have much to discover about the specific processes that drive this type of cosmic ray across the universe). The Auger collaboration focused its work on the 77 ultra-high energy cosmic ray events recorded since 2004, when it began collecting data. The observatory detects particles from air showers, created when the cosmic rays encounter the upper atmosphere, cascading into secondary particles that can spread across forty or more square kilometers.
Image: One of the Auger Observatory’s surface detectors. The Andes Mountains provide a snow-capped backdrop to the west of the surface detector array. Credit: Pierre Auger Observatory.
By ultra-high energy, we’re talking about cosmic rays with energy above 4 x 1019 electron volts, or 40 EeV. And it turns out that the highest energy events Auger has detected — the 27 events with energy above 57 EeV — did not arrive at the Earth from random directions. The group compared them with the known locations of 318 Active Galactic Nuclei, finding the cosmic rays correlated well with the locations of AGNs in nearby galaxies like Centaurus A. Galaxies with an AGN seem to be those that have suffered a collision with another galaxy or otherwise experienced a massive disruption in the last few hundred million years.
The data seem compelling: A random origin would imply that only five or six of the high energy events would correlate with the known locations of active galaxies. The researchers believe there is only a one in one hundred chance that what they are seeing is random. That the AGNs themselves are relatively nearby is accounted for by the assumption that ultra-high energy cosmic rays from more distant sources would lose energy before reaching Earth because of interactions with the cosmic microwave background.
With the most energetic cosmic rays hitting the Earth only rarely — about one event per square kilometer per century — it takes a large observing platform to record useful information about them. But Auger’s unique configuration in Argentina seems up to the task. It’s an array of detectors covering 1200 square miles and including 1400 particle detectors, with 1600 planned. The detectors are large, instrumented water tanks that can detect the particles produced by air showers (see image above). In addition, four sites with a total of 24 telescopes detect the flashes that occur when a cosmic ray triggers such a shower.
Among the flurry of news releases covering the cosmic ray news, this one from the University of Utah provides perhaps the most comprehensive backgrounder (and that makes sense, as Utah is home to the High Resolution (HiRes) Fly’s Eye experiment, a cosmic ray detection project on a smaller scale than Auger). The paper from the Pierre Auger Collaboration (with extensive list of authors listed at the end) is “Correlation of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects,” Science Vol. 318. No. 5852 (9 November 2007), pp. 938-943 (DOI: 10.1126/science.1151124). Abstract available.
by Paul Gilster | Nov 10, 2007 | Culture and Society |
When we think interstellar, the possibility of a sudden breakthrough offering quick travel — Epsilon Eridani in an afternoon — often dominates the debate. But the second path to the stars is the more gradual migration approach that Gregory Matloff, Les Johnson and the artist C Bangs talk about in their Living Off the Land in Space (New York: Copernicus, 2007). As discussed in this article in the Brooklyn Daily Eagle, the trio made their case at NYC College of Technology/CUNY on Thursday evening, leading off not with a starship but a prairie schooner. The point is trenchant: How can we leverage and extend existing technologies to get us into deep space without breakthroughs in physics?
“In going into space, we need to think differently. All of these technologies we describe in our book could be done today,” says Johnson (NASA MSFC), who manages the agency’s Space Science Programs and Projects Office. Technologies such as solar sails, their great historical precedent being the clipper ships that once plied our seas. Solar sails are entirely plausible within today’s physics and offer an evolutionary engineering pathway to bigger and faster missions and, who knows, perhaps beamed-power versions that might ultimately take us to the stars. The point being that some of us see interstellar emigration as inevitable with or without the paraphernalia of Star Trek‘s Enterprise.
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Growing plants in space? It’s tricky business, says David Hemming in Gardening in Microgravity. For one thing, water doesn’t permeate the soil in these conditions the way it does on Earth, while pollination can also be affected. And watch out for plant debris, which could block critical ventilation systems. But as we commit ourselves to extended stays in space, we’ve got to learn about plants that can adapt to low light intensity and high carbon dioxide conditions. Hemming cites Mary Musgrave’s “Growing Plants in Space” on the subject, appearing in CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 2007. 2, No. 065, 9 pp (available here).
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Lately, I’ve found myself in more and more conversations about SETI. Why, since we’re spending so much time looking and listening, haven’t we heard anything? The inevitable corollary is, why are my tax dollars going to fund something this unlikely to pay off? The answer usually comes as a surprise: In the United States, at least, SETI has been funded solely through private donations since 1993. It’s frustrating to have to keep pointing this out, and I gather Seth Shostak (SETI Institute) is feeling some of the same heat. Thus his recent essay attempting a justification for continuing the SETI search.
For those who will argue that those private funds should be re-directed, Shostak looks to past precedent:
Shouldn’t philanthropists opt for the most effective project, in terms of societal improvement? That may sound good, but even aside from issues of free will, that argument leads to a terminally murky battle on what’s important and what isn’t. And sometimes what’s unimportant today can become very important tomorrow.
Consider some examples. In Italy at the start of the 17th century, Medici family members Ferdinand and Cosimo proffered a regular allowance to an ambitious academic from Padua, Galileo Galilei. The guy found spots on the Sun and moons around Jupiter. You could have bought some meals with that money instead. But Galileo’s work turned our worldview upside down by showing that Copernicus was right. I’m glad he got the florins.
Two hundred years later, Emperor Joseph II of Austria ponied up some coins to fund Wolfgang Mozart. Was this a good idea? Mozart was just writing music, for goodness sake. You can’t eat music (unless you’re a goat). But I can feast on it, and I do.
It’s a strong case, but the fact that Shostak has to make it speaks to the dangers of public inattention. SETI sells itself through the sheer wonder of learning we are not alone. But the notion that the entire enterprise is some vast NASA project that is sucking the life out of budgets that would otherwise feed the poor persists among many of those who have only a casual interest in the subject. That’s not good for SETI, whose advocates need to get across not just its reliance on private philanthropy but the energizing possibility that individuals — not just their governments — can make a real difference in determining humanity’s place in the cosmos.
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The conference Humans in Outer Space – Interdisciplinary Odysseys, held in Vienna on October 11-12, created a trans-disciplinary dialogue of the sort we could use in the SETI/METI debate. The latter, which concerns the question of listening or, alternatively, actually broadcasting messages to nearby stellar systems, would benefit from the Vienna model, bringing in not just space scientists but anthropologists, psychologists, philosophers, political scientists and writers to attempt a broad human perspective on big issues. Nicolas Peter (European Space Policy Institute) spoke of a ‘third age’ of exploration:
“It will involve industry, universities and other non-governmental organisations. This adventure will be driven primarily by a quest for knowledge, involving not only the hard sciences but arts and humanities as well. We’re evolving towards an open market situation where a lot of new actors will be able to join the new space race.”
Can a global exploration policy one day emerge to help us coordinate our growth into the Solar System? In today’s fractious world, the idea seems the unlikeliest of dreams, but it’s the kind of dream worth striving for as long as a healthy commercial space sector continues to push the envelope of the possible. What we don’t need are monolithic governmental space strategies that proceed at the expense of private initiatives. What we can hope for are multidisciplinary approaches that draw on international cooperation while allowing sound ideas to flourish. Here’s to Nicolas’ open markets, new actors and their dreams.
by Paul Gilster | Nov 9, 2007 | Exoplanetary Science |
If you’re looking for an analog to the Sun, you have to do more than find a solitary G-class star. Three stars markedly like the Sun — 18 Scorpius, HD 98618, and HIP 100963 — still differ in having several times more lithium than our star. Figuring out whether the low amount of lithium is an unusual trait has ramifications for the search for life in the cosmos. You could theoretically push the issue by saying that the Sun’s composition is unlikely to be found elsewhere, making extraterrestrial life rare.
But that conjecture, which was a stretch to begin with, may be dampened by the recent findings about HIP 56948. 200 light years away in the constellation Draco, the star mimics the Sun’s lithium levels. And there’s an additional bonus: Bill Cochran’s team, also at McDonald, has demonstrated that HIP 56948 hosts no ‘hot Jupiters,’ giant worlds so close to their primary that they orbit in a matter of days. Thus this finding, developed using data from the 2.7-meter instrument at McDonald Observatory (University of Texas), shows us an interesting target for future terrestrial planet hunter missions, and perhaps for SETI researchers as well.
Image: HIP 56948 is more like the Sun than any known star. Located 200 light-years away in Draco, the dragon, the star is too dim to see with the unaided eye. Credit: Tim Jones/McDonald Obs./UT-Austin.
Hot Jupiters, of course, do not rule out terrestrial worlds in the same system. We know little enough about how the formation and probable migration of these planets into the inner system would affect smaller rocky worlds. But finding true Solar analogs gives us the chance to study stars like ours in a broader context, learning how accurate it is to consider Sol as the baseline for a variety of astrophysical studies. Moreover, the same team has found a second Solar analog with similar lithium levels, HIP 73815. It’s a list that’s bound to grow.
The paper is Melendez, “HIP 56948: A Solar Twin With a Low Lithium Abundance,” in press at Astrophysical Journal Letters (abstract).
by Paul Gilster | Nov 9, 2007 | Culture and Society |
Emily Lakdawalla is hosting the 28th Carnival of Space at her Planetary Society weblog, a compilation including plenty of coverage on Comet Holmes, the unusually active object that, New Scientist opines, may have suffered a collision with an asteroid. Intriguing speculation, though Centauri Dreams readers will probably find Music of the Spheres‘ entry on 55 Cancri the most interstellar-minded. Bruce looks at the similarities between that system’s new planet and Allen Steele’s Coyote. From the novel of the same name, it’s a moon orbiting a giant planet in its star’s habitable zone, a scenario tantalizingly similar to the recent discovery.
