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

spike spike66 at att.net
Sun Feb 17 03:10:40 UTC 2013

```On Behalf Of Tomasz Rola

On Sat, 16 Feb 2013, spike wrote:

>>... Regarding your notion of a physical impact, this might transfer some
> momentum, and here's how you estimate how much: find the speed of
> sound in the rock, take the closing speed and calculate a cone going
> aft from impact site outward along the path of the impact.  Then
> calculate a cone with the longitudinal axis being the closing velocity
> and both transverse axes being
[...]

>...Spike, thanks for hints. However... well, I don't know... I mean you
sound like honest and good man, but why on earth would you like me to do
such horrible things?

>...But ok, I will do like you say, only later, ok?

Regards,
Tomasz Rola

--

{8^D

OK, I didn't state it very clearly.  Let me try it Damien Broderick style.

You have perhaps seen what happens when a BB is fired at a glass window.  It
often creates a cone-shaped punch-out, with the impact side hole the size of
the BB and increasing in radius along the path of the BB.  When an impactor
hits a meteoroid at sufficient velocity, we can expect a hole the size of
the impactor on the impact side, increasing in radius as we go back, with a
cone half angle of about 4 to 8 degrees.

With that information, we might be able to estimate the momentum transfer to
the meteoroid, which I fear might be disappointingly small.  At those speeds
I doubt it would break up the rock, but rather would punch a clean
cone-shaped hole.  Of course our intuitions fail for we have little or no
experience in real life with impacts at 20 km/sec.

I would like to see a good simulation of it however.

spike

```