[ExI] (NASA.gov) NASA to chronicle close Earth flyby of asteroid (fwd)

Tomasz Rola rtomek at ceti.pl
Sat Feb 16 15:59:06 UTC 2013

On Sat, 16 Feb 2013, Anders Sandberg wrote:

> On 16/02/2013 01:59, Tomasz Rola wrote:
> > Very unnerving is the realisation that despite whole NEO search, this 
> > thing has caught the planet pants down (or I don't know how else to 
> > sum this up).
> Nah, this is a too small impactor to be part of spaceguard and the other 
> NEO programs (their cut-off is around 140 meters). This size will 
> typically be picked up by radar or observations during the final plunge, 
> if they are detected at all. As I argue in my commentary 
> http://blog.practicalethics.ox.ac.uk/2013/02/live-from-the-shooting-gallery-what-price-impact-safety/ 
> looking for them is not a bad idea, but it is not a major way of 
> improving planetary safety.

The same numbers can tell somewhat different stories. Yours is hard to 
disagree with, but OTOH Russian impactor had - by recent estimates - 15m 
diameter. I read about incoming NEOs in a kind of systematic manner, out 
of curiosity, and it's not unusual to have predictions about 25m objects 
coming in a month or so. The 2012DA14 is said to have 65m and I knew about 
it since few months (and it had been first observed year ago). So I guess 
it is not unthinkable to have a warning about 15m impactor coming in a 
week. Um, wait, maybe not. The thing marched 12mln km in a week (assuming 
20kmps pace). Ok, but if we set up perimeter at Moon's orbit, this gives 
about 4-5h alert time before impact. Should be enough to prepare some a-a 

I mean, it is cool to say something like "bah, a kilometer-wide impactor 
we could bother about but mere 20m is peanuts to us, it's only umpteen 
statistical deaths per year". But I think limits should be pushed a little 
further. Especially that we should maybe bother more about small to medium 
size and faaast asteroids, coming out of nowhere. Right now we are mostly 
good to find things that float on Earth-like orbits. AFAIK, of course.

Tomasz Rola

** A C programmer asked whether computer had Buddha's nature.      **
** As the answer, master did "rm -rif" on the programmer's home    **
** directory. And then the C programmer became enlightened...      **
**                                                                 **
** Tomasz Rola          mailto:tomasz_rola at bigfoot.com             **

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