My mistake on the method of propulsion... Thanks for clearing that up
for me Chris.. ;)
On 11/4/2010 10:03 AM, Chris Peterson wrote:
Eric-
The Yarkovsky effect does not work by vaporizing material. It is
related to the momentum of photons.
In the case of outgassing, the momentum is very low compared with the
momentum of the nucleus, so the effect on the orbit is small as well.
The Yarkovsky effect is also quite small on a body the size of
Hartley. I think Yarkovsky dominates because it is a continuous
process over the entire orbit, whereas outgassing only occurs during
the time the nucleus is near the Sun. But in reality, both effects, as
well as others (like gravitational perturbation) produce an orbit that
can't be accurately predicted too far into the future. It is important
to regularly recalculate orbital elements for bodies like this if very
precise position information is required. I noticed during the flyby
this morning that there seemed to be a miscalculated close passage
time, which was corrected by a few minutes when the comet's orbit was
recalculated.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message ----- From: "Meteorites USA"
<[email protected]>
To: <[email protected]>
Sent: Thursday, November 04, 2010 10:35 AM
Subject: Re: [meteorite-list] EPOXI images of Comet Hartley 2
Hi Gary, Your explanation of the outgassing of comets and Count
Deiro's question, made me think of one of the proposed ways of
deflecting asteroids which uses the Yarkovsky effect to focus the
suns energy on the outer surface of the asteroid thereby vaporizing
material and causing a propulsive force to nudge the asteroid into a
new orbit.
So, if the Yarkovsky effect will work on asteroids, what's the
difference between that, and Comet Hartley 2's outgassing on the
orbit of the body? Is the force from the outgassing that much less
than what the Yarkovsky effect could produce?
Regards,
Eric
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