April 2006

A Practical Positron Rocket?

April 19, 2006

Antimatter seems the boldest — and newest — of propulsion concepts, but in fact Eugen Sänger’s work on the uses of antimatter in rocketry goes back to the 1930s. The German scientist thought it would be possible to reflect gamma rays produced by the annihilation of electrons and positrons to produce thrust. His work wowed [...]

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A Targeting Strategy for Optical SETI

April 18, 2006

Optical SETI has generally adopted the conventions of conventional SETI by targeting nearby, Sun-like stars. It’s a strategy that makes sense, but given the number of potential transmitting stars and the need for broader surveys, what we’d ultimately like to find is a strategy for optimizing our chances, a way of looking for optical signals [...]

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The Riches of an ‘Empty’ Field

April 17, 2006

The image below is merely a marker — it leads to something far grander. For what you’re looking at is a small part of a vast image of ‘empty’ space, made with over 64 hours of observations using the Wide-Field Camera on the 2.2-meter La Silla telescope in Chile. Rather than linking to a simple [...]

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A Key Paper from an Astounding Source

April 15, 2006

Most papers about interstellar flight appear in serious venues like Acta Astronautica or the Journal of the British Interplanetary Society. The latter, in fact, has emerged as the leading arena for such discussions, and the growth of the arXiv site has brought many new ideas to light in the digital realm. It may be surprising, [...]

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Microlensing and Its Limits

April 14, 2006

Recent exoplanet detections like the ‘super Earth’ found orbiting a red dwarf 9000 light years away have put the spotlight on gravitational microlensing. The phenomenon occurs when light from a background star is deflected by the gravity of an intervening object; in other words, one star passing quite near or in front of a far [...]

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Updating the SETI Hunt

April 13, 2006

I see that SETI@home is concerned about being able to continue its matching funds program from the University of California and is actively soliciting donations. It’s a terrific project, of course, and the numbers are staggering: with early expectations of raising 100,000 participants, SETI@home wound up with 5.4 million volunteers who donated 2.4 million years [...]

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A Warm ‘Saturn’ Around 51 Peg?

April 12, 2006

A brief heads-up on the ongoing work on 51 Peg, which Greg Laughlin and team are studying to see if additional planets can be found in the voluminous data. 51 Peg, remember, was the first example of an extrasolar planet being found around a main-sequence star. The dataset goes back ten years and is far [...]

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10th Planet a Highly Reflective Puzzle

April 12, 2006

We know little enough about our system’s tenth planet (once called 2003 UB313 and now unofficially called Xena), but as new observations come in, we’re learning that it is a mysterious place indeed. The latest news comes from the Space Telescope Science Institute, which pegs the object’s size at five percent larger than Pluto. That [...]

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Astronomical Breakups in the News

April 11, 2006

The sky seems to be full of interesting objects that are breaking apart. They’re always worth studying, as we learned through the impacts of the famous ‘string of pearls’ comet — Shoemaker-Levy 9 — on Jupiter in 1994. For one thing, the celestial display they afford is uncommonly interesting; for another, they are a reminder [...]

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On Interstellar Dust and Fast Probes

April 10, 2006

Here’s why we’ll have to know a great deal about the interstellar medium — the stuff between the stars — before we ever send out probes at a substantial fraction of lightspeed. The gas and dust forming into dark, concentrated knots in the image below creates so-called ‘Bok globules,’ named after astronomer Bart Bok, who [...]

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