Re: [ASTRO] Minicomets bombarding Earth
Jega Arulpragasam (jega@ziplink.net)
Wed, 16 Jul 1997 09:45:49 -0400 (EDT)
Over a week agao, Jim Scotti wrote:
> More importantly, these objects are not being detected by us here at
>Spacewatch. We actually see objects in the size range that Frank expects
>his small comets to be - around 10 meters - and we see them out beyond the
>distance of the moon. From the rate we detect these objects, we estimate
>the impact rate at about 10 per year. That's about 1 million times less
>frequent that Frank's estimated impact rate. We should see these objects
>at rates close to 10,000 per night or one every several seconds.
(snip)
> Another bit of evidence against the small comet hypothesis is the lack
>of detections by the Apollo Seismic experiments. Frank originally argued
>that tidal breakup worked in the moon's vicinity and reduced his mini
>comets to a vapor cloud, but that was shown to not work, and his more
>recent electrostatic breakup mechanism does not work near the moon, so his
>objects hit the moon intact.
Am I right in the impressions i) that Louis Frank's new data is NOW
widely accepted (Dressler a convert?) as showing diffuse patches of water
vapor appear at very high altitudes in the atmosphere, and then
dissipate, and ii) that the alleged, hypothesized if you like, minicomets
have NEVER been observed before breakup, and iii) that such mechanisms as
have been proposed for breakup are not very plausible?
If I am right on these points, it would seem that a natural hypothesis
would be that rather than having compact (10 m) objects of low albedo
breaking up, the objects are much bigger and much more diffuse -- in
fact, about as diffuse as they are when they are first detected by
Frank's instruments. If this were to be the case, would Spacewatch have
detected these objects, even if 10,000 of them were passing by each
night? Would the Apollo seismic experiments be sensitive enough to
detect their impact on the Moon?
While I would I would have guessed not, is the reason for this hypothesis
not being discussed that the answer to at least one of these questions is
"Yes!"? Or is it because there is some overriding theoretical reason
that such diffuse objects cannot exist for any length of time? Would a
loosely (gravitationally) bound set of water molecules following almost
identical orbits get disrupted in a (relatively) short time -- say,
just millions of years or less?
>First, the lunar atmosphere was measured and there's nowhere
>near enough water present.
Ah! A "diffuse cloud" hypothesis would seem to have the same dfficulty
with this as would any " compact minicomet" hypothesis. Nevertheless,
I'm tempted to ask the question. (I have never resisted temptation
before -- and now's no time to start.) Below what rate of (let's say
uniform) deposition, on the visible surface of the Moon, of water from
diffuse clouds would this NOT have been detected?
I would deeply appreciate a response from anyone having the information
to answer these questions. Thank you.
Jega Arulpragasam
Lunenburg, MA 01462
71 deg 43'W 42 deg 37'N