Asteroid 2008TC3 is now the Almahata Sitta meteorite

For decades, geologists have classified meteorites based on their geochemistry, and astronomers have classified asteroids based on their reflectance spectra. Until now, these have been difficult to cross-correlate. To do so requires one of two methods. The first is to build a robotic spacecraft to land on an asteroid, pick up a piece, and safely return it to the Earth. The second is to find an asteroid on a collision course with Earth, and then pick up the pieces after the impact. This paper uses the latter approach.

Emily and Amir over at the Planetary Society have excellent write ups. Have a look if you haven't seen them. The smoke trail pics are particularly cool.

For long time fans of the lounge, this result shows that my estimate was 22 km NW of the main debris field, and 12 km NNE of the closest fragment. Had I remembered to move south by tan(latitude) x altitude from the apparent fireball location, I might have actually picked it. Now you know why I'm not a structural geologist.

I think it's fantastic that three of the Sudanese are high in the authorship list, and that they involved their undergrads on the project. Opportunities to do cutting edge science don't come along all that often for undergrads at African universities, and it is great that these young people were able to make a genuine contribution to Earth and planetary science. The nature paper is a fairly easy read, for those with access.

The paper briefly mentions that some of the carbonaceous matter in this meteorite was diamond. I referenced a couple of ureilite diamond papers in my thesis; they are considered classic examples of impact-formed diamonds.

Of course, the wonder of this discovery inevitably brings in discussion of missiles in space to deflect future impactors. I would like to go on the record as against such projects.

First of all, they would deprive us of great science, like this.

Secondly, the missiles and bombs inevitably nominated as the tools of choice for asteroid deflection are way more dangerous than asteroids are.

Thirdly, any technology which can deflect an asteroid away from the Earth can deflect an asteroid from one part of the Earth to another. We have enough ways of killing each other already.

And finally, bolide's don't kill people. Volcanoes do. And nobody wants to blow them up.

We don't blow up tsunamis, or hurricanes, or river floods either. We predict when and where they are going to happen, tell people to get out of the way, and then fix the damage after the event. There is no reason the same procedure can't be used for impactors, once early detection and prediction becomes commonplace. Given any sort of discount rate at all, a warning system will be far cheaper, safer, and saner than building a multi-zillion dollar doomsday bomb to deflect the asteroid.

Meteorite detection will only improve with time. In fact, I suspect that within my lifetime, an Earth-impacting object on a collision course with an accessible part of the developed world will be detected at least 24 hours in advance. I am even prepared to make a prediction about the first such event. That is this:

Once the orbit is calculated, and the target and time is announced, more people will travel into the target zone than away from it. I might even be one of them.

Jenniskens, P., Shaddad, M., Numan, D., Elsir, S., Kudoda, A., Zolensky, M., Le, L., Robinson, G., Friedrich, J., Rumble, D., Steele, A., Chesley, S., Fitzsimmons, A., Duddy, S., Hsieh, H., Ramsay, G., Brown, P., Edwards, W., Tagliaferri, E., Boslough, M., Spalding, R., Dantowitz, R., Kozubal, M., Pravec, P., Borovicka, J., Charvat, Z., Vaubaillon, J., Kuiper, J., Albers, J., Bishop, J., Mancinelli, R., Sandford, S., Milam, S., Nuevo, M., & Worden, S. (2009). The impact and recovery of asteroid 2008 TC3 Nature, 458 (7237), 485-488 DOI: 10.1038/nature07920