Optical telescopes can have very wide fields of view and are relative
cheap to build and operate making them the obvious choice, especially
in this cash strapped era.
Most important, the photons are FREE.
Unlike all those expensive electrons you
have to buy for radar...
Sterling K. Webb
--------------------------------------------------------------------
----- Original Message -----
From: "Richard A. Kowalski" <kowal...@lpl.arizona.edu>
To: <meteorite-list@meteoritecentral.com>; "Meteorites USA"
<e...@meteoritesusa.com>
Sent: Thursday, April 14, 2011 12:40 AM
Subject: Re: [meteorite-list] Space Radar?
--- On Wed, 4/13/11, Meteorites USA <e...@meteoritesusa.com> wrote:
> From: Meteorites USA <e...@meteoritesusa.com>
> Subject: Re: [meteorite-list] Space Radar? (Was: Cold Asteroids May
> Have A
Soft Heart)
> To: meteorite-list@meteoritecentral.com
> Date: Wednesday, April 13, 2011, 10:15 PM
> Richard, List,
>
> Since smaller meteoroids and asteroids are nearly
> undetectable in space, and we're currently searching
> optically with telescopes. Is it possible to detect
> meteoroids/asteroids with space based radar?
>
> Will radar even work in space? If so, what's the range, and
> how would it work? Do we have something like this?
>
> I know we have space based weather radar satellites, but
> what about pointing them into empty space to search for
> asteroids?
>
> Sorry if this is a dumb question... Just curious.
>
> Regards,
> Eric
Not a dumb question and one that I field every so often.
While it could be possible to detect NEOs and other asteroids usig a
space based radar system, such a system would be ungodly expensive and
difficult to construct and operate.
Remember that radar works by sending our the radio signal and then
observing the reflected energy. The radio telescopes here on earth
that observe asteroids and other planets using radar are huge (The
dishes at Goldstone and Arecibo) and they require huge amounts of
power to operate. The engineering alone would make the project
unlikely and the power requirements make it a non-starter.
Also, while we are familiar with air traffic and weather radar systems
here on the surface, these are vastly less powerful than what would be
required by an NEO detection system. ATC radar can be much less
powerful than required to "paint" every target because most aircraft
have a transponder installed. The transponder in effect "hears" the
radar pulse and transmits essentially a "Here I am!" message in
response. Asteroids of course have no such transponder, so you have to
"paint" the asteroid and then detect the reflected signal.
Finally, most radar systems have narrow beams. This Field of View is
tiny on the two dishes I mentioned. The optical community frequently
gets requests for continuing observations of NEOs that will be
observed with radar to make sure they point the telescope precisely
enough that the asteroid is in their beam. Even a handful of
arcseconds off (an arcsecond is 1/3600 of a degree) and they miss the
asteroid entirely.
Optical telescopes can have very wide fields of view and are relative
cheap to build and operate making them the obvious choice, especially
in this cash strapped era.
Hope this helps
--
Richard Kowalski
Catalina Sky Survey
Lunar and Planetary Laboratory
University of Arizona
http://www.lpl.arizona.edu/css/
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