[meteorite-list] Space station moves to avoid debris

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sat, 3 Feb 2007 18:55:19 -0600
Message-ID: <010401c747f7$248cf420$904ae146_at_ATARIENGINE>

Hi, Rob, Darren, List,

    One gram traveling at 1000 m/sec, when stopped
abruptly, releases its kinetic energy, which is 1000
joules [kg x (m/s)^2]. The combustion energy of
TNT is 4600 joules per gram, so that energy release
is the equivalent is 217 milligrams of TNT. Doesn't
sound like that much, does it?

    In the USA, the legal limit for fireworks is 50
milligrams of pyrotechnic material. [Code of Federal
Regulations, Title 16, Volume 2, Section 1500.85].
This is the traditional M-50, or perhaps the "cherry
bomb." Since pyrotechnics are weaker than TNT,
imagine four to eight "cherry bombs" concentrated
on one tiny spot...

    Of course, today's "cherry bombs" are not as
good as yesterday's (pre-regulation) "cherry bombs,"
but as a child, I fractured the brass casing (3" x 12")
of a shell for 37mm anti-aircraft cannon with ONE
"cherry bomb." No better fun for an nine-year-old
than a bagful of small high explosives and a bunch
of old cannon shells, is there?

    How thick are the walls of your space station?
Your space suit? Your visor? That hose you're
breathing through? Or any of the thousands of
things you need to stay alive?

   If that gram is coming in from beyond the
Earth's gravity, you could close on it at almost
20 km/sec, the equivalent is about 85 grams of
TNT. Disastrous.

    If the orbit of a piece of rubble is not oriented
with your orbit, but at an angle to it, you and the
object are "crossing" at some vector product of
your velocities. This is the most serious and likely
hazard.

    If you were in an equatorial orbit and the rubble
was in a polar orbit and you had a geometrically
"perfect" collision, the impact velocity would be
1.414 times the orbital velocity, with each gram
carrying the equivalent of 27.3 grams of TNT in
kinetic energy. Known in the trade as the Chop
Suey Special.


Sterling K. Webb
-------------------------------------------------------------
----- Original Message -----
From: "Rob McCafferty" <rob_mccafferty at yahoo.com>
To: "Gerald Flaherty" <grf2 at verizon.net>;
<meteorite-list at meteoritecentral.com>
Sent: Saturday, February 03, 2007 2:16 PM
Subject: Re: [meteorite-list] Space station moves to avoid debris



--- Gerald Flaherty <grf2 at verizon.net> wrote:

 but a centimeter sized particle traveling at
> those speeds??
> Help.
> Jerry Flaherty

What Darren said is how I understand it too. As for
1cm particles, nah This shield is designed to protect
against micrometeorids travelling at a relative speed
of 20km/s. It'll not protect you from big stuff though
I suppose the relative speeds of orbital debris is
likely travelling much slower.

Even so, wouldn't fancy their chances against a pea
sized bit of weather sat even if it ONLY had a
collision speed of 1000m/s

Rob McC
Received on Sat 03 Feb 2007 07:55:19 PM PST