In response.

Yes you could do that though I don't think it'd be of any scientific 
significance to do so.

The initial impulse required to eject rocks with enough speed to get to earth 
may produce some shock effects in the rock.  You may prefer to use rockets if 
you wanted pristine rocks so that the momentum is applied over a greater period 
rather than all at once.

You'd need a good aim. Hitting the atmosphere at an angle where the atmospheric 
deceleration doesn't vapourise the rock would be key. Once you get past the 
lagrange point, the earth would capture the rock (Lagrange point is where lunar 
and terrestrial gravity balance). That's all the return motor on the Apollo 
command module did, get it past that point.
>From there it took about 3 days and you're falling all the way. You're going 
>pretty quick by the time you hit the atmosphere by then. Apollo had to skip 
>across the surface of the atmosphere a few times to lose speed. They had the 
>fortune of manaouvering jets to get in line to hit the earth just right with 
>mid course corrections. A projectile wouldn't have that.

Would it be a meteorite? I would suggest it would be. It came from out there 
and if it makes it to the surface, it's a meteorite. 
I'd probably call it an "anthropogenic meteorite", one caused by the activities 
of man (just like "anthropogenic carbon dioxide". There are plenty of natural 
CO2 sources as well). The meteorites in our collections are currently "natural 
meteorites".

The classification is just a name that tells us the origin. As an example, the 
lunar surface contains "Ferroan Anorthosite" which is anorthosite with iron 
embedded in it. I have several kilos of "Archaen anorthosite" next to my back 
door. It's terrestrial and comes from the Archaen geological period of earth. 
The labels do not effect the chemistry of the rocks but they do help identify 
where they came from. The formal classification and distinguishing of one from 
another may require sophisticated techniques but they are there to pinpoint 
them to a time, place and history.

Rob McC


--- On Fri, 3/20/09, Meteorites USA <e...@meteoritesusa.com> wrote:

> From: Meteorites USA <e...@meteoritesusa.com>
> Subject: [meteorite-list] Artificial Lunar Meteorites?
> To: d...@fallingrocks.com, "meteorite-list@meteoritecentral.com" 
> <meteorite-list@meteoritecentral.com>
> Date: Friday, March 20, 2009, 5:30 AM
> I've got a few silly questions...
> 
> Let's say you had a large canon powered by compressed
> air or some other high pressure gas.
> 
> If you fired a projectile ( a moon rock ) from the surface
> of the moon toward Earth, would you be able to create enough
> force to reach escape velocity?
> If so, how long would it take for that projectile to reach
> Earth?
> Would the projectile continue to increase speed after
> leaving the barrel of the canon or does it stay at the
> velocity from which it leaves the barrel?
> If all these things were possible, and you were able to
> calculate velocity, trajectory, and the entry point into the
> Earth's atmosphere, would the stones survive the trip
> through our atmosphere? And/or how large would the
> projectile have to be to survive atmospheric entry? (I know
> this is a loaded question, please don't get caught up on
> this one, the next one is the question I'm really
> curious about) ;)
> 
> And finally...
> 
> If the projectile (moon rock) did survive all of this,
> would it be considered a meteorite?
> 
> Scientifically speaking wouldn't this be an interesting
> experiment?
> 
> Send a lander to the moon with a BIG canon and launch some
> moon rocks dude! ;)
> 
> Regards,
> Eric Wichman
> Meteorites USA
> 
> 
> In response to
> 
> Dave Gheesling wrote:
> 
> "...Meteorites don't enter our atmosphere attached
> to spheres, and presumably that artificial contraption may
> have made for a different-than-typical result...."
> 
> All best,
> Dave
> www.fallingrocks.com
> ______________________________________________
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