Thursday, December 30, 2010

SPACE - Two For Science

"'Zombie' satellite returns to life" by Denise Chow, 12/29/2010


A "zombie satellite" that spent months sending out signals while it was adrift in orbit has sprung back to life, resetting itself after its unexplained breakdown in space earlier this year.

"The most critical phases of Galaxy 15's recovery have been successfully completed," officials at Intelsat, the communications provider that owns the satellite, said of the newly responsive satellite.

The Galaxy 15 communications satellite lost contact with its flight control center in April. But in an unexpected twist, the stricken satellite's telecommunications broadcast package remained in operation. With Intelsat operators unable to control the solar-powered satellite, Galaxy 15 continued to transmit signals, posing a risk of interfering with the signals of neighboring satellites.

In the months that followed, Intelsat worked closely with the operators of other broadcast satellites to ensure that their communications services — which included television broadcasts — would not be affected when Galaxy 15 drifted by.

But that drama in space has ended.

On Dec. 23, the battery on Galaxy 15 — which relied on solar panels pointed at the sun to generate power — became completely drained, Intelsat officials said. Once that happened, the satellite reset itself as designed and began accepting commands from Intelsat's control center.

"We have placed Galaxy 15 in safe mode, and at this time, we are pleased to report it no longer poses any threat of satellite interference to either neighboring satellites or customer services," Intelsat officials announced.

"Universe's most massive black holes got huge early" by Staff 12/29/2010


The first rapid growth spurt of the universe's most massive black holes occurred much earlier than astronomers previously thought, and are still growing fast, a new study finds.

A team of astronomers from Tel Aviv University in Israel determined that the first period of fast growth of the most massive black holes occurred when the universe was only about 1.2 billion years old not 2 to 4 billion years old, as had been thought. Astronomers estimate the universe is about 13.7 billion years old.

In the study, astronomers also determined that the universe's oldest and most massive black holes are also growing at a very fast rate. The findings will be detailed in an upcoming issue of the Astrophysical Journal. [ Photos: Black Holes of the Universe ]

Black hole giants

Most galaxies in the universe, including our own Milky Way, harbor supermassive black holes at their center. These black holes vary in mass from about one million to about 10 billion times the mass of the sun.

To detect these giants, astronomers look for the enormous amount of radiation emitted by the gas that falls into the black holes when they are actively accreting matter. This gas pouring into massive black holes is thought to be the means by which they grow.

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