Friday, September 23, 2011

Chicken Little


Space Junk in Orbit



Lottie Williams & her Space Crap

Chicken Little was in the woods one day when an acorn fell on her head. It scared her so much she trembled all over. She shook so hard, half her feathers fell out.
"Help! Help! The sky is falling! I have to go tell the king!"
So she ran in great fright to tell the king. Along the way she met Henny Penny.
"Where are you going, Chicken Little?"
"Oh, help! The sky is falling!"
"How do you know?"
"I saw it with my own eyes, and heard it with my own ears, and part of it fell on my head!"
"This is terrible, just terrible! We'd better hurry up."
So they both ran away as fast as they could.

The famous story of Chicken Little is a cautionary tale. It warns us not to get too excited about things that may at first scare us so much that we harm ourselves, but later turn out to be benign. The above fable ends with Chicken Little and her friends getting suckered into a fox's den and then eaten, which is much worse than having an acorn fall on her head.
Of course if there is ample evidence that a catastrophe is truly looming then it would be entirely appropriate to act out in a manner that is beneficial to oneself and others. Calmly.
I'm reminded of the old saying: "Just because you're paranoid doesn't mean that people aren't out to get you."
Sometime this afternoon, between noon and 6:00PM EST, a bit of the sky will really rain down upon us... about 26 large pieces of a satellite that ran out of gas in 2005, some weighing over 300 pounds. The debris will stretch along a 500-mile path, but the thing is, we're not quite sure where that 500-mile stretch will be.
The 6.5 ton (about the size of a city bus) Upper Atmosphere Research Satellite (UARS) was launched on September 12th, 1991 aboard the Space Shuttle Discovery. It was intended to study the Earth's atmosphere for three years, especially ozone and the chemical compounds found in the ozone layer which protects the planet from about 97 to 99% of the Sun's high frequency ultraviolet light, which is potentially damaging to the life forms on Earth. As a matter of fact life on Earth could probably not exist without this protective layer (animal and plant life at least), that is why man-made chlorofluorocarbons (CFCs) and bromofluorocarbons used in aerosols sprays, refrigeration, and industrial cleaning were phased out during the 1980s and 90s (I wonder how easy it would be to do so now with the Tea Baggers in power and so many Republican climate change deniers).
UARS also measures winds and temperatures in the stratosphere as well as the energy input from the Sun.
After UARS initial three year run many of its ten instruments were still functioning and continued to relay data. Indeed six of them were still working this month as the satellite's orbit decayed as a result of it running out of fuel in 2005. Essentially at this time, UARS is completely out of control and tumbling back into our atmosphere at approximately 18,000 MPH (UARS circles the Earth about once every 96 minutes).
Fortunately, as the satellite delves deeper into the Earth's atmosphere it will burn up through friction with that atmosphere... most of it... except for those 26 pieces which are too big to burn completely. They will slow down considerably though, and those pieces are not expected to land anywhere within the United States.
But we don't know where they will land exactly due to the fact that as UARS hits the atmosphere it will change it's trajectory because it is uncontrolled, similar to a stone skipping across the surface of a pond when thrown, it's orbit will change somewhat (as will the atmosphere itself, due to fluctuations of the solar outflow interacting with the atmosphere), making predictions of where it will finally land impossible at this time.
Here's a short video of UARS as it began to interact with the atmosphere last, week taken by amateur astronomer Thierry Legault:
Some people are rather worried about this whole thing, large chunks of hot metal falling from the sky possibly creating all kinds of havoc and damage. Radio host Bill Press concluded his program yesterday morning with commentary concerning the falling satellite. He was worried the debris might land on people and hurt them.
Most people are not too worried however. There is a whole lot of man made crap up there in orbit that falls back to Earth every once in a while. Space Junk or Space Debris (or Space Crap as I like to call it) it's called, which are objects in orbit around the Earth that we sent up there but no longer serve any useful purpose, in fact they're often a hazard to newer operational spacecraft like the International Space Station, which needs to move it's position in space whenever a monitored piece of space crap comes near, which may impact with it at high velocities. It doesn't matter really how big it is, the space crap's velocity relative to the ISS is what matters.
Space crap consists of everything from spent rocket stages and defunct satellites to erosion, explosion and collision fragments. There's a picture of all of the space crap circling the Earth at about 18,000 MPH above. Someone should really go up there and clean that crap up.
Big things have fell down on us before without causing too many problems, some a lot bigger that UARS. The American Skylab space station fell to back Earth in July 1979. It weighed about 100 tons and was big as a house... literally. Bits of it fell in Western Australia (and the Indian Ocean), but no one was injured. However local authorities did fine NASA $400 for littering (the asshats at NASA never paid).
The Russian space station Mir fell back to us in 2001. It weighed 135 tons, but fell into the South Pacific Ocean and didn't hit anything but a bunch of fish. Considering two-thirds of the planet's surface is covered by water, the odds are in favor that anything falling down from the sky will land in it.
In 2003 pieces of the shuttle Columbia, which had exploded upon reentry, rained down on parts of Texas and Louisiana and didn't hit anybody. In fact there's only been one recorded instance of a piece of space crap returning to Earth and hitting someone... and it happened in Oklahoma.
In 1997 Lottie Williams was walking along through a park in Tulsa, minding her own business, when she saw a flash of light in the sky. She thought it was a meteor. A little while later she was struck on the shoulder by a piece of metal thought to come from a disintegrating rocket (picture above).
NASA confirmed that the timing and location of the incident were consistent with the re-entry and breakup of a second-stage Delta rocket that fell to Earth after orbiting for several months. The main wreckage was recovered a couple of hundred miles away in Texas.
Amazingly Lottie was not hurt. She was struck a glancing blow, and the debris was relatively light and probably traveling at a low velocity. It was also subject to wind currents, which mitigated the impact even further.
She was very lucky. I once saw a dramatization of an actual meteorite shooting right through a guy and killing him instantly on "1000 Ways to Die."
Then of course there's this:
NASA has calculated a 1-in-3,200 chance of anyone on Earth being hurt by its satellite’s return to Earth.
And the odds of any one particular person being hit are much lower, about one in 21 trillion.
However if a piece of UARS does happen to land near you, dear readers, you're instructed not to touch it, and go find a policeman or something and have them take over.
I'm told that if you try to steal a piece of UARS, and cart it off home with you, it's against the law, and the NASA cops will come and get you.
Freaking NASA cops! They're everywhere.

Addendum: "NASA's decommissioned Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. EDT Sept. 24. The Joint Space Operations Center at Vandenberg Air Force Base in California said the satellite entered the atmosphere over the North Pacific Ocean, off the west coast of the United States. The precise re-entry time and location of any debris impacts are still being determined. NASA is not aware of any reports of injury or property damage.

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