[meteorite-list] Comets vs. asteroids

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Mon, 12 Jan 2009 22:09:52 -0800 (PST)
Message-ID: <860945.73620.qm_at_web36903.mail.mud.yahoo.com>

Hi Bob -

> You replied:

> The cost for construction, launch and mission operations of
> a single surveillance sensor capable of achieving a fraction of what
> you want would dwarf the current expenditures of all ground-based
> NEO work.

Yes, and so...

> While I certainly agree that a space-based platform offers
> clear advantages over the ground,

We agree there.

> you have to weigh that high cost against the degree of incremental
> improvement provided.

What you have to weigh that high cost against is the fact that mankind nearly went the way of the dinosaur several times over the last six million years, and several mt DNA groups disappeared more recently than that, and several nations disappeared more recently than that.

> NEO searches *are* funded, and I believe at a level commensurate with the > risk.

I don't believe so. Of course, the difference between you and myself is in our estimates of the risk. Mine is built on historical and geological data... yours on hopes and Morrison's theoretical models. Speaking of money, how many tens of millions has NASA wasted looking for Nemesis? Any way I can get 15% of that under the False Claims Act?
 
> The risk, while real, is puny compared to more mundane threats.

While we certainly have a lot of "mundane" threats, risk equals probability of occurrence versus loss per occurrence. Since you brought up threats, what is NASA expecting, invaders from Mars?

> You and I will almost certainly not live long enough to see the
> earth impacted by any object of significance (and I plan to live another > half century or more.)

Perhaps, but based on the impacts at Rio Curaca in 1930 and Rupunini in 1935 and the small bit in Norway in 2006, try a five kiloton blast in 2022 from a 30 m fragment of SW3.
 
> The odds of a 75-meter impactor (of any flavor) are indeed
> close to one, but only if you're willing to wait long enough. But you
> can't say the odds of being blind-sided by one are unity

With NASA's current and planned detectors, yes I can.

>-- we have space-based sensors operating 24/7

Now that's news there - are your IR detectors capable of finding 75 m objects with the luminence of a chunk of charcoal at several lunar distances? Figure in the travel times, and that's about what's needed just for a simple warning of Tunguska type objects.

> and dozens of highly capable ground-based instruments
> scattered around the globe, so there is at least some
> chance of spotting such an interloper before impact.
> (Don't forget the 3-meter object that Catalina Sky Survey spotted about a
> day before impact in Sudan.)

Specious rationalization of the worst sort, Bob - you mention 3 meters, but you do not mention luminence. Did you work the Columbia foam impact by any chance?
 
Once again, it was a comet that killed the dinosaurs, not an asteroid.
 
> What's the difference?

Don't you know the difference between a comet and an asteroid?

> Do you think comets are invisible?

No. Do you?

> In terms of detection, there is no difference between an earth-crossing
> asteroid and a short period comet.

Oh really?

> If you're arguing that the main threat is a long-period comet, then
> fine. But a space-based sensor won't help you in that case.

Really?

...
> That's simply not true unless you're talking about
> significant aperture and a huge number of CCD detectors (gigapixel
> class). How much aperture are you talking about putting up in orbit?

You put it on the Moon - see the CAPS study, if NASA has not destroyed all their copies of it. In that case, ask the Chinese space leadership to give you a copy back.

> The PANSTARRS PS1 telescope construction was completely
> funded by the Air Force. Gates and Simonyi provided $30 million to LSST
> (Large Synoptic Survey Telescope). While LSST has the capability to
> detect smaller NEOs, this is not its purpose.

Then why is NASA advertising it that way - what is NASA doing, lying again?

Actually, all it really comes down to again and again and again is the NASA PR machine fobbing off bad impact hazard estimates and bogus impact science. One more time, it wasn't an asteroid that killed the dinosaurs, it was a comet.
 
> You seem to have this obsession with comets, the unsubstantiated claim
> that NASA doesn't care about them,

NASA impact risks from comets and asteroids are published, and they're defective.

> and that somehow we have designed special, hobbled sensors that are blind > to them and can only detect asteroids.

Its simply the make pretend aspects of NASA's rationalizations that drive me up a wall.

> And we're all aware of your disdain for Michael Griffin, who
> nevertheless happens to be one of the smartest people who
> has ever run NASA.

I first met Mike around the time of SEI - at least then he didn't try to pretend that he knew what he was doing. Smartest people to ever run NASA? Try Paine, try Fletcher, try Truly, try Goldin - at least none of them were on Thiokol's payroll. Oh yeah, I really love the way Mike resized the CEV to make it fit the Ares 1. Thankfully, there's Direct to get us out of this mess.

> Mike has a half dozen degrees in physics and engineering, and I
> had first-hand experience working with him on the Delta 180
> programs when he was at JHU/APL and SDIO.

If SDIO or the Air Force want a large solid launcher for defense purposes, then they can pay for it out of their budgets. Wernher von Braun said it a long time ago: solids lack abort modes.

> You may not like the direction that he took NASA, but his decisions were > not made in ignorance.

The historical office debrief will come soon. And the correspondence will be available in the archives. All of it.

In the meantime, here's a hot idea: let's shut down NASA, and get Walmart to buy CAPS from China for us: Flaster, Bletter, Cheapel. Or do you think that the southern and western states' military industrial companies might object?

> --Rob

E.P. Grondine
Man and Impact in the Americas



      
Received on Tue 13 Jan 2009 01:09:52 AM PST