Tuesday, February 15, 2011

Harassing Comets

Tempel 1

The Formation of Comets 4.6 Billion Years

Deep Impact

Sneeking Up On Tempel 1

Just Before The Hit

KA BOOM! Take That Comet!

Stardust Approaching

Just imagine if you can dear readers you're a nice comet, tooling around the inner solar system between the Mars and Jupiter, making a complete rotation around the sun (the comet's year) every five or six years, not hurting anybody, minding your own business, doing this for thousands, or millions of years, possibly longer, when POW! you've been given a massive cheap shot from this tiny spacecraft from the United States of America!
How rude.
Well that's exactly what happened on the 4th of July back in 2005 to the short period comet Tempel 1 by the Deep Impact spacecraft, the first time we've assaulted a comet in this manner, assuredly not the last.
As a matter of fact last night, on Valentine's Day, we returned to the aggrieved hunk of ice, dust, and rock to photograph it, kind of adding insult to injury if you ask me.
Why did we do this? With the both Republicans and the Democrats (Obama's budget presented to Congress yesterday) both wanting to place the burden of their mismanagement of the economy on the backs of the working poor and middle class, rather than raising taxes on the ultra-rich and corporations that quite frankly don't need all that money to begin with, why are we spending million of dollars to go out and offend harmless comets that just want to get along? The simple answer dear readers is to see what's inside.
Why do we care what's inside a comet? Funny you should ask. It all goes back to what a comet actually is.
A comet is a hunk of ice, dust, and rock.
We've got plenty of ice, dust, and rock here at home. What's so special about comet rock?
Comet rock has been around since the origen of the solar system about 4.6 billion years ago (I apologize to my Christian friends who continue to believe the Earth is only 10,000 years old, however you're simply dead wrong... and I can prove it!). That means comet rock, dust, ice, and gases are those that existed when the solar system was born. Primordial rock, dust, ice, and gas if you will. By studying it we are studying the conditions that existed before the Earth and other planets were formed, giving us a better understanding of the accretion processes that allowed our solar system to come into being (above is an actual picture of comets forming during the birth of the solar system, not easy to come by, I'll tell you).
Rocks here on Earth, or the Moon, or other planets have gone through various processes like erosion and weathering, or if they're underground from heat and pressure. So they can't tell us what the conditions of the local area in space were like 4.6 billion years ago. No, we need pristine comet rock for that.
So, back in 2005 the Deep Impact spacecraft snuck up on the unsuspecting comet on Independence Day, a distracting ploy most likely. As you can see in the component picture above there is that "Smart Instrumented Impactor," attached. It has a camera embedded in it as well. The whole thing weighed 815 pounds back here on Earth, so it had quite a bit of mass to it. It had a payload of 660 pounds of 100% copper. Why you ask? Why do we waste our good American copper on this comet? Good question. The good folks at NASA wanted to photograph the crater that would be made after the impacter hit the comet, and analyze the debris that would fly out which was the whole purpose of the mission, to see what the heck was inside the poor comet. The NASA people did not expect there to be any copper already in the comet. I don't know why. Anyway, copper reacts slowly with other elements so if there was some there they did not expect it to interfere much with their measurements.
Okay, now we get to the dastardly deed. As I said the spacecraft snuck up on the unsuspecting comet. It released the impactor and got out of the way. The impactor began taking its own pictures. There's one above if you don't believe me. The last picture it took before sucker punching Tempel 1 was 3.7 seconds before impact. It quickly maneuvered in front of the comet so they actually collided head on... and POW (picture above)! KA BOOM (or there would have been a "KA BOOM!" if there was any sound in outer space, but there's not, so the whole thing happened silently. (my apologies to George Lucas, and any other producer/director who has used sound effects in outer space scenes, however you're simply dead wrong. Stanley Kubrick is the only director that I know of who had the guts not to use sound effects in the space scenes of 2001, and he came away with a classic of modern cinema))!
At first the NASA mission controllers couldn't even see the new crater they had created because of all of the dust that had ejected due to the collision, but later discovered it was about 328 feet wide and up to 98 feet deep. Outgassing from the impact lasted for 13 days. Scientists were able to collect a whole bunch of interesting data, and determined that Tempel 1 possibly formed near the gas giant planets Uranus and Neptune a long time ago.
Okay, that brings us to the Stardust spacecraft that took pictures of Tempel 1 again, last night, from a distance of 125 miles, taking a series of 72 high resolution pictures as it zipped by at more than 24,000 miles per hour. Again those clever folks at NASA used a holiday to distract its victim. This happened at 8:37PM my time.
Tempel 1 will be the first comet to be seen at close range twice, and scientists will make a then-and-now comparison, to see how much it has changed in 5 1/2 years.
“Here’s a chance where we can see what has changed, how much has changed,” said Joseph Veverka, a professor of astronomy at Cornell and the mission’s principal investigator, “so we’ll start unraveling the history of a comet’s surface."
Interestingly enough the Tempel 1 encounter with Stardust was not the spacecraft's original mission. Heck no. After it was launched in 1999, the Stardust circled the Sun and flew by Earth for a gravity boost to rendezvous with the comet Wild 2 near Jupiter. On Jan. 2, 2004, the Stardust came within 149 miles of the comet and deployed shields to protect itself from cometary dust while extending a 160-square-inch collector filled with a material called aerogel. It scooped up a lot of comet dust (interstellar particles too). Stardust then returned to Earth and jettisoned the collection capsule which fell back to the ground on top of a bunch of Mormons somewhere in Utah.
Mission scientist thought to themselves, hey, our budget is being cut due to the horrible handling of the economy under George Bush and the Republicans, and the Stardust craft is still up there... might as well send it on another mission, which they did back in 2007.
Well at least Tempel 1 can take some satisfaction in knowing that after last night's encounter the Stardust craft will run out of gas and won't be able to bother it again.
It is free once again to roam the inner solar system, winding it's way around the sun, without fear of molestation.
For the time being that is.

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