[meteorite-list] Artificial Lunar Meteorites?

From: Jeff Grossman <jgrossman_at_meteoritecentral.com>
Date: Fri, 20 Mar 2009 06:23:14 -0400
Message-ID: <49C36E92.3010207_at_usgs.gov>

As to the question of "is it a meteorite?", not according to the Rubin
and Grossman definition (Meteorite! 4 (3), p. 24-25, 1998):

"A meteorite is a natural solid object that was transported by natural
means from the body on which it formed to a region outside the dominant
gravitational influence of that body and was later
accreted by a natural body larger than itself."

jeff

Sterling K. Webb wrote:
> Eric Wichman wrote:
>
>
>> 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.
>>
>
> Why not use a small rocket or a rail gun or a mass driver or...?
> Doesn't matter to the problem how you launch it, OK?
>
>
>
>> 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?
>>
>
> That's an engineering question. If you're a good enough
> engineer, the answer is YES.
>
>
>
>> Would the projectile continue to increase speed after leaving
>> the barrel of the canon...?
>>
>
> Eric, go read a book by that nice Mr. Galileo or Mr. Newton.
> Seriously. Get a simple old-fashioned physics text about dynamics
> and the basic laws of motion and energy.
>
> If you toss a rock, does it continue to speed up AFTER
> it leaves your hand? If it did, then the experience of tossing
> a rock would be that it goes further and further, faster
> and faster, until it's so fast that it begins to glow with
> frictional heat and blazes out the Earth's atmosphere like
> a meteorite!
>
> Funny. When I toss a rock, it just makes a little arc
> and goes Plop! in my neighbor's yard.
>
>
>
>> or does it stay at the velocity from which it leaves the barrel?
>>
>
> If you toss a rock straight up, does it continue at the same
> constant 32mph that it had when it left your hand and climb
> at a steady speed upward against the Earth's gravity, until it
> leaves the Earth's atmosphere behind and enters space...
> all at a stately 32mph?
>
> When I toss a rock straight up, it slows down and down
> until it can't go any higher, then falls back and hits me on
> the head. In the interests of experimental science, I suggest
> you get some good hefty rocks and try these tests. Space
> travel would be so easy if your Laws of Motion were true.
>
> OK, skip the tests.
>
> You're on the Moon. You pick up a big rock and fit it
> into your Super Duper Steam Powered Slingshot, capable
> of firing a rock at 2380 meters per second, which oddly
> enough is the Moon's excape velocity. (Actually you could
> be a bit slower and still get to the Earth.)
>
> The rock leaves the Super Duper Steam Powered Slingshot
> at 2380 meters per second. After only one second of traveling
> upward against the Moon's gravity, the rock is only traveling
> at 2378.378 meters per second. That's because the Moon's
> gravity is pulling back down on the rock with a force sufficient
> to slow it down by 1.622 meters per second.
>
> The Moon's gravity will continue to slow the rock at the rate
> of 1.622 meters per second per second until, about 2 days later,
> the rock is just barely crawling along at a snail's pace thousands
> of miles above the Moon, when it reaches a place where the
> strong gravity of the faraway Earth is pulling foward on the rock
> just as strongly as the gravity of the much closer but weaker
> Moon is pulling back on it, and the rock starts to fall toward
> the Earth, now gaining speed instead of losing it.
>
> Three days or so later, your mild-mannered rock will come
> blazing into the Earth's atmosphere at a speed of almost 11,186
> meters per second!
>
>
>> Would the stones survive the trip through our atmosphere?
>>
>
> Here's where aim counts: the right angle of approach or perhaps
> a grazing orbit or two before re-entry... Anything is possible
> if you have sufficiently accurate control of your path. It's
> do-able.
>
>
>
>> If the projectile (moon rock) did survive all of this,
>> would it be considered a meteorite?
>>
>
> That would depend on how the argument on this List came out...
>
>
>
>> Scientifically speaking, wouldn't this be an interesting experiment?
>>
>
> Scientifically speaking, no... But, dude, it would be so much
> kewler than a potato cannon or even a watermelon cannon!
>
>
>
> Sterling K. Webb
>
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
>

-- 
Dr. Jeffrey N. Grossman       phone: (703) 648-6184
US Geological Survey          fax:   (703) 648-6383
954 National Center
Reston, VA 20192, USA

Received on Fri 20 Mar 2009 06:23:14 AM PDT