Category Archives: meteorites

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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life, meteorites

It’s Raining Primordial Soup

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and the Meteorite You Rode in On

A few entries back I talked about the symposium about life in the universe that I attended last week. One of the talks we heard was about the existence of minerals and molecules in space that are the precursors to the building blocks of life. These are things like amino acids, which are pivotal in the soup of life.

Image:NWA869Meteorite.jpgWell, news comes today that confirms the the idea that meteorites are very rich sources of amino acids. Given that meteorites rain down on Earth all the time (and have done so throughout our planet’s history, it’s pretty much a given that they were generous donors to the “primordial soup” from which life on Earth sprang a few billion years ago. Scientists at the Carnegie Institution of Washington have discovered high concentrations of amino acids in two meteorites; those levels are ten times higher than other previous measurements. (For those of you who’d like to see the science results, the scientists involved have uploaded a paper for your reading pleasure.)

Amino acids are the backbones of proteins, which themselves are the “stuff” of which life is made. That’s a very simplified version of the larger biochemical story. Essentially, you have to have proteins to get life, and while some amino acids undoubtedly simmered from the stew of stuff available on early Earth, it’s plausible to assume that some of them rode in from space on meteorites. Specifically, a type of meteorite known as CR Chondrite , which contain some of the oldest and most primitive organic materials dating back to the time of our solar system’s formation. (The image at left is a sample of the NWA 869 meteorite, which is a chondrite of a similar type to a CH.)

We’ve long known that comets, which come from the Oort Cloud and have peppered Earth throughout its history, also carry organics and have long been thought of as carriers of such materials. Finding amino acids that contributed to Earth’s “soup of life” in meteorites is another step toward understanding the conditions and materials that formed the solar system