[meteorite-list] FW: Comets vs. asteroids

[Rob Matson]

Hi E.P.,

I hesitate to respond from work since the oddities of the
MetList prevent my posts from reaching it when I reply from
my work e-mail address (perhaps to the relief of many members).
Nevertheless, I'll press on and forward the message from my
home account when I get there (though the subject matter is
veering off-topic, and few people care about this subject).

> Hi Bob -

[FYI, "Bob" is not my name. I realize that it's a popular
short version of "Robert", but I have never signed an email
by anything other than Rob.]

> There were so many falacies in your post that with my stroke
> damage I let some major howlers get through in my reply.

E.P. (Ed?) -- I don't post falacies, I post facts. On those
occasions when I post opinions, I label them as such. You're
not going to trip me up when the subject matter is solar
system dynamics, comets, asteroids, optics, physics, orbital
mechanics or general astronomy, so please don't even try.

> Actually, turbine, combustion chamber and propellant line
> failures give some warning, and the (s)hutdown/abort systems
> can be brought into play.  Not so with solids, which have
> sudden catastrophic failure modes ...

I don't think I need to remind you that it wasn't the Shuttle's
SRBs that exploded -- it was the External Tank. Yes, the SRBs
were *responsible* for rupturing that tank, but that wasn't a
fault of the solid propellant. If the Shuttle had been 100%
solids it wouldn't have exploded. The crew would still have
been lost (since there was no escape option in 1986), but *had*
there been a rapid egress system, their chances of survival
certainly would have been better if they hadn't been riding
a liquid bomb.

> Why Mike resized the CEV so that it exceeded EELV capablities
> and required a large solid launcher is a great question. Given
> your work with Griffin in SDIO, I would ask about the need for
> large solid launchers for defense purposes, but then this is a
> public forum. I assume Garver, Ladwig, and Obama already know,
> they'll share want they want to with us sometime next week...

Completely off-topic and of no interest to me.

>> Well, where do you draw the line on the expense of your
>> "insurance policy"

> Ask the Chinese. Their national emblem is a dragon commemorating
> a comet; their first emperor was killed in an impact event; they
> lost nearly all their commercial shipping fleet to impact mega-
> tsunami around 1431 CE, which left them open to foreign attack
> and centuries of suffering.

That's a cop-out -- I'm not asking the Chinese, I'm asking you.
How much money are you willing to throw at this perceived
deficiency? If you were presenting a proposal to Congress or
the American people, do you really think your ancient Chinese
examples would be that persuasive?

> I haven't broken CAPS out into CZ5 launches yet, to come up with
> remin costs. Whatever the cost, the value returned by CAPS far
> exceeds the value of flying a few men to Mars for a few days.

To average citizens in 2009 trying to stay in their homes and
feed their families, I'd say there was little value in either
activity. The only way you'll get their attention is through
extortion:  perhaps threatening to deprive them of American
Idol or The Bachelor.  --Rob