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SPACE & SCIENCE NEWS: February 2003
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Probing the heart of darkness Feb 19, 2003
Mars: water, water, everywhere ... Feb 17, 2003

the core of the Milky Way Galaxy
Probing the heart of darkness
(Feb 19, 2003)

For the first time, astronomers have tracked an individual star in orbit around the supermassive black hole that lies at the center of our galaxy and whose location is indicated in the photo. The star in question, known as S0-2, is 15 times as massive as the Sun, appears to be about 10 million years old, and is orbiting the central black hole at a distance of a mere 68 AU (just over 10 billion km - a bit more than the Earth-Pluto distance) and an astonishing speed of 9,000 km per second. The research team, led by UCLA's Andrea Ghez, used the Keck Observatory on Hawaii to obtain unprecedented views of the region of space around Sgr A*. Their data provide the best estimate yet of the mass of the black hole and the extent of its event horizon – the surface from within which nothing can escape back into the outside universe. The mass comes out to three million solar masses – give or take half a million – and the event horizon must be considerably less than 68 AU. But as one puzzle is solved, another emerges. How can a star as big as S0-2 have formed so close to such a gravitational monster? Only more observations will tell.

For more, go here (BBC).

Martian gullies
Mars: water, water, everywhere ...
(Feb 17, 2003)

The latest findings from the Mars Odyssey spacecraft currently in orbit around the Red Planet suggest that there's enough water ice on Mars, if melted, to inundate the entire planet to a depth of at least 13 cm (5 inches) – and that includes only the ice found within the top couple of meters of soil. This is extraordinarly good news both for the prospects of indigenous life, either extinct or extant, and those for future manned Mars missions. Effectively, every kilogram of Martian soil would yield half a kilo of water if it were baked in an oven by visiting astronauts. Localized natural melting would also provide one of the basic requirements for microbial life. And there are strong signs, notably in the form of gullies on the sides of some craters and ravines (such as those shown here) that, on occasions, water still runs across the surface of the planet.

For more on this, visit the Mars Odyssey homepage, this article at, or my own encyclopedia entries, including Mars, life on Mars, Martian vegetation. For more, go here (BBC).


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