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December 10, 2010

Carnival of Space 180

The Carnival of Space 180 is up at Starry Critters

Astronotes writes that Red Dwarf stars could be the most important type of star in the universe.

A G-type star has but a brief window for life to flourish on its planets, before it expands to a red giant in a cosmic eye blink, then spending perhaps a quadrillion years as a cooling white dwarf. In contrast, a red dwarf will shine steadily but faintly on its children across a lifetime perhaps a thousand times that of the Sun. Eventually there will be a time when red dwarfs are the only living stars in the Universe, all the others which gleam so bright today will be dead stellar husks. If thinking beings can arise on the planets of red dwarfs, one day the Universe will belong to them.

The Sun is expected to exist as a main sequence star for some 10 billion years, but a red dwarf one tenth its size ought to shine on for a thousand times longer, ten trillion years.

Red dwarfs not only outnumber every other type of star in the Universe but will outlive every other type of star.




Centauri Dreams considers the transition from interplanetary travel to interstellar travel.

As we continue our push out into the Solar System, we’re going to run into the natural limits of our navigation methods. The Deep Space Network can track a spacecraft from the ground and achieve the kind of phenomenal accuracy that can thread a Cassini probe through a gap in the rings of Saturn. But positional errors grow with distance, and can mount up to 4 kilometers per AU of distance from the Earth.

To go beyond the Solar System, we’ll need a method that works independently, without the need for ground station assistance. Pulsar navigation is one way around the problem.

A pulsar interstellar GPS system in a recent simulated test had the accuracy of the order of a few hundred meters if a continuous set of data is assumed.

An X-ray pulsar based positioning system could pinpoint an object to within 10 meters, an improvement on the 100-meter or so accuracy of the radio pulsar system. Either system would be accurate enough to track a spacecraft speeding at 19,000 meters per second. X-ray antennas are also smaller and lighter than radio antennas.

Pulsars are extremely weak radio sources and detecting them normally requires a large radio telescope -- a heavy payload for spacecraft. So the researchers propose to create their own sources of pulsing radiation by planting bright radio wave emitters on celestial bodies like Mars, the moon or even asteroids. Pulsars that emit X-rays, a much brighter signal.

Pulsar-based systems may not be as precise as GPS, but they could be a backup system for GPS if the ground control for the satellites fails.

This site had the following in the 180th carnival of space -
My God its three times more full of stars. A better count of red dwarf stars finds 20 times more in elliptical galaxies. The estimate for stars in the universe is now 300 Sextillion.

There is probably a dark jupiter (or several) around the edge of the solar system

Life can have arsenic instead of phosphate as a basic building block. NOTE: there has been a lot of recent controversy about the quality of the research.


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