Daily Archives: October 6, 2008

meteorites, meteors, NEOs, spaceguard survey

Asteroid Piece on Course for Earth

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No Damage Expected and It’s Not a Threat

As reported on Phil Plait’s Bad Astronomy site and through the Minor Planets Center at the Harvard-Smithsonian Center for Astrophysics, an object called 2008 TC3 is going to enter Earth’s atmosphere tonight and burn up over Sudan.  It’s very small–only about 2 meters across–which means that by the time it gets through our atmosphere, only a few small rocks will be left to rain down on the desert (if any of it is left to fall). The entry time, as reported by Steve Chesley of NASA JPL is 2:45 UT October 7 (equivalent to 10:46 p.m. Eastern time in the U.S.).  For folks along the path of entry, it should be a great bolide to watch as it streaks in from space!

So, the amazing thing about this predicted impact is NOT that it is going to occur, although that’s pretty neat. It’s not even that it’s a piece of space rock coming in — although it should be pretty darned spectacular to see!  No, the coolest thing about this whole thing is that this is the first time an incoming asteroid and potential impact has ever been predicted. The sightings of this thing have been coming in from the SpaceGuard Survey over the past half day and they are good enough to predict the time of the object’s entry into our atmosphere. It’s pretty amazing that the survey has been able to spot something this small.

Now, in case you’ve seen some woo-woo reports about this thing, it’s not anything more than an incoming rock from space. There’s lots of them out there, and given enough time, we’re bound to see one or two of this size come in every once in a while.  There’s nothing magical or mystical about it. It’s all quite natural.

Of course, questions are arising about its possible effect on Earth. According to Andrea Milani at the University of Pisa,

“the effect of this atmospheric impact will be the release, in either a single shot or maybe a sequence of explosions, of about 1 kiloton of energy. This means that the damage on the ground is expected to be zero. The location of these explosions is not easy to predict due to the  atmospheric braking effects. The only concern is that they might be  interpreted as something else, that is man-made explosions. Thus in  this case, the earlier the public worldwide is aware that this is a  natural phenomenon, which involves no risk, the better.”

Folks who track these things for a living are hoping that scientists will be able to mobilize some spectrographs and cameras to do some in-depth studies of the object as it comes in.  Such studies will help astronomers figure out the shape and chemical composition of the naturally occurring rocks it was made of, and help determine where it first formed in the solar system some 4.5 billion years ago.

The meteor should be visible from eastern Africa. It will likely appear as an extremely bright fireball traveling rapidly across the sky from northeast to southwest. It should enter the atmosphere over northern Sudan at a shallow angle.

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chemistry, cosmic chemistry

Searching for Life Elsewhere

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The Chemistry of Life

Some years ago I wrote a documentary planetarium presentation called Oceans in Space. It’s about the search for life on other worlds. We made a big deal in the show about how life needs three things to survive: water, warmth, and organic material (food). That’s fine as far as it goes, but the devil is in the details when it comes to figuring out what ELSE life needs to exist.

Of course the criteria describe Earth’s environment, but they also very generally cover a number of possible life-supporting places NOT on our planet. But, just because a place might satisfy all three criteria doesn’t guarantee that it supports (or even has) life. The solar system has a number of worlds that have water and warmth and even some organic material to serve as “food” for life forms. Mars has many places that were once inundated with water. Some of the smaller icy water-rich moons of the outer solar system, such as Enceladus and Europa, could also support microbial life (if nothing else). But, so far we’ve found no evidence for life in these places, and in fact, there are many places on Earth where life doesn’t thrive. What do they have in common?

According to researchers at the University of Arizona, who have been chosen by NASA to focus on the criteria that will guide our future searches for life on other worlds, it’s possible that those places may lack enough chemical elements to support life.  So, while having water and warmth are a good start, if you don’t have the right chemical mix, it may be tough to start and sustain life.

Chemistry IS necessary for life, there’s no question about it. Last March I attended a seminar at Radcliffe Institute in Cambridge, Massachusetts, and the chemical origins of life were the main topic of conversation. (You can read the article I wrote about it here.) The message that “chemistry is life” was really forcefully brought home — and the details are fascinating.

The UA team (and its partners at the University of California, Riverside; University of California, Merced; Rice University and University of Illinois – Chicago, as well as NASA Goddard Space Flight Center, the Australian Centre for Astrobiology at the University of New South Wales and the National Autonomous University of Mexico, under the direction of Dr. Ariel Anbar, plans to refine the criteria to guide the search for life by characterizing life’s elemental requirements. In other words, they’ll delve into the necessary chemistry that life needs to form and thrive.

The team will explore the relationship between the elemental composition of organisms and their environments, the impact of planetary processes on the abundance of bioessential elements, and the effects of astrophysical processes on the abundance of life-supporting elements. This is an important area of study for astrobiology and I look forward to seeing results from their work as time goes by.

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