April 2006

A New Probe of Dark Energy

April 29, 2006

What we know about dark energy can be pretty much summed up in these words: “We know that it dominates the universe. In fact, it comprises an estimated 73 percent of the universe, while so-called dark matter accounts for 23 percent, and matter of the familiar kind — the stars, galaxies, all known life — […]

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Cometary Breakup Continues

April 28, 2006

73P/Schwassmann-Wachmann is proving to be a far more interesting object than first anticipated. The comet is closing toward the Sun and will swing around it on June 7, passing the Earth along the way at a distance of 11.7 million kilometers. The fascination comes from watching its ongoing disintegration, which has broken the comet into […]

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Via Solar Array to the Outer Planets

April 27, 2006

New Scientist is covering the work of Rudolph Meyer (UCLA), who envisions a vehicle that sounds for all the world like a cross between a solar sail and an ion engine. And in a way, it is: Imagine a flexible solar panel a solid 3125 square meters in size, and imagine this ‘solar-electric membrane’ weighing […]

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A Powerful Resource on ‘Hot Jupiters’

April 27, 2006

That oh so interesting planetary system around 51 Peg continues to fascinate exoplanet hunters. After all, this was the first planetary discovery around a main sequence star, and the formidable dimensions of the radial velocity dataset accrued before and since the discovery may lead to other planets in the same system. For the latest on […]

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Ultraviolet Limits on Habitable Worlds

April 26, 2006

Habitable zones, and our idea of what constitutes them, change over time. We know, for example, that the habitable zone around a given star should migrate outward as main sequence stars become brighter with age. Thus the notion of the ‘continuously habitable zone’ (CHZ) has emerged, the region where a planet remains in habitable conditions […]

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Modeling Black Hole Mergers

April 25, 2006

Any guesses as to what the most powerful event in the universe is? According to a team of NASA scientists working with breakthrough computer modeling techniques, it’s the merger of two massive black holes. When the event occurs, gravitational waves muscle out from the collision site at the speed of light. Each such merger generates […]

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Eberhardt Rechtin: Death of a Pioneer

April 24, 2006

Centauri Dreams is saddened to learn of the death of Eberhardt Rechtin, a pioneer of deep space exploration. The list of his accomplishments is long: Rechtin served as CEO of Aerospace Corporation (El Segundo, CA), as chief engineer of Hewlett-Packard, and as director of the Defense Advanced Research Projects Agency. But his career is best […]

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A Boost for Innovative Interstellar Explorer

April 22, 2006

The Innovative Interstellar Explorer mission discussed recently in these pages has received new support in a study of alternative propulsion concepts. IIE, you may remember, would use radioisotope electric propulsion (REP), tapping xenon as propellant. The mission’s goal is to deliver a scientific payload to 150-200 AU within a 15 to 20 year time frame; […]

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Three Planets, and a New Category

April 21, 2006

Three new planets have just been announced, but contrary to expectations, the number of planetary detections has not been picking up in recent times. The peak rate was 34 planetary discoveries in 2002, with the years since showing about 25 planets per year. There are a number of reasons for the slowdown, among them the […]

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Antimatter’s Advantages (and the Catch)

April 20, 2006

One of the beauties of antimatter is its efficiency. A fission reaction uses up about 1 percent of the available energy inside matter, whereas the annihilation of antimatter and matter converts 100 percent of the mass into energy. No wonder tiny amounts of antimatter can have such powerful effects. Put a gram of matter together […]

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