2011年9月19日星期一

An estimated 26 of those pieces will survive the re-entry

"There are too many variations on solar activity herve leger dresses for cheap which affect the atmosphere, the drag on the vehicle," said Nicholas Johnson, chief scientist for orbital debris at NASA.

The good news is that the satellite will probably splatter into the open ocean, because Earth is a water planet. And humans, for all their sprawl, occupy a very limited portion of its surface.

NASA did a calculation of the odds that someone would be struck by its debris. It's very unlikely: About a 1-in-3,200 chance that one person somewhere in the world will be struck. That's not the odds for any specific person (say, a reader of this story), but for the entire human population, which is about 7 billion.

The satellite was launched on the space shuttle Discovery in 1991 and spent 14 years studying the atmosphere as part of an effort to understand, among herve leger geometric jacquard dress other things, the human influence on climate change. But NASA decided in 2005 that its work had become redundant to that performed by other satellites, and the satellite received its scientific pink slip.

When satellite fragments hit the surface, people should be cautious about handling them. There's nothing toxic in the mix, but somebody could get cut on the metal, Johnson said. And, for the record, the debris belongs to the U.S. government.
It's the biggest piece of NASA space junk to fall to Earth in more than 30 years. It should create a light show. The satellite will partially burn up during re-entry, and, by NASA's calculation, break into about 100 pieces, creating fireballs that should be visible even in daytime.

An estimated 26 of those pieces will survive the re-entry burn and will spray themselves in a linear debris field 500 miles long. The largest chunk should weigh about 300 pounds.

As the Friday-ish crash gets closer, NASA will refine its estimate cheap herve leger bandage dresses of timing and location, but the fudge factor will remain high.
Serreze said that in 2007, the year of record low Arctic sea ice, there was a “nearly perfect” set-up of specific weather conditions. Winds pushed in more warm air over the Arctic than usual, helping to melt sea ice, and winds also pushed the floating ice chunks together into a smaller area. “It is interesting that this year, the second lowest sea ice extent ever recorded, that we didn’t see that kind of weather pattern at all,” he said.

The last five years have been the five lowest Arctic sea ice extents recorded since satellite measurements began in 1979, said CU-Boulder’s Walt Meier, an NSIDC scientist. “The primary driver of these low sea ice conditions is rising temperatures in the Arctic, and we definitely are heading in the direction of ice-free summers,” he said. “Our best estimates now indicate that may occur by about 2030 or 2040.”

There still is a chance the sea ice extent could fall slightly due to changing winds or late season melt, said Meier. During the first week of October, CU-Boulder’s NSIDC will issue a full analysis of the 2011 results and a comparison to previous years.