[FPSPACE] Fear and Loathing on the Launch Pad

[Jens Kieffer-Olsen]

-----Original Message-----
From: E.P. Grondine [mailto:epgrondine at hotmail.com] 
Sent: Saturday, May 2, 2009 03:21 AM

> The reason Baptistina type asteroids are rare 
> is because they're captured dead comets and 
> comet fragments.

 Well, let's take a brief look at the orbit of
 298 Baptistina. Its eccentricity is 0.096, its
 perihelion and aphelion 2.047 AU and 2.481 AU
 respectively. 

 That makes for an asteroid with an orbit much closer
 to circular than most asteroids, since according
 to the Wikipedia experts Prussing and Conway: "Most
 of the solar system's asteroids have eccentricities
 between 0 and 0.35 with an average value of 0.17." 

 The eccentricities of comets lie in an entirely
 different range. From the same Wikipedia article:
 "The eccentricity of comets is most often close to 1.
 Periodic comets have highly eccentric elliptical orbits,
 with eccentricities just below 1; Halley's Comet's
 elliptical orbit, for example, has a value of 0.967.
 Non-periodic comets follow near-parabolic orbits and
 thus have eccentricities very close to 1. Examples
 include Comet Hale-Bopp with a value of 0.995086 and
 Comet McNaught with a value of 1.000030."

 Your favourite comet SW3 has an eccentricity of 0.6934
 and corresponding perihelion and aphelion of 0.9391 AU
 and 5.187 AU respectively. That makes it a full-blown
 comet.

 Arguing as you are, Ed, that 298 Baptistina with
 a near-circular orbit is a "captured dead comet"
 comes across, frankly speaking, like a load of bull!

--
Jens Kieffer-Olsen
Slagelse, Denmark