[meteorite-list] Space Radar?

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 14 Apr 2011 01:35:34 -0500
Message-ID: <6B0D1330E2DF4F3A89A33CE28F665BB3_at_ATARIENGINE2>

> 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" <kowalski at lpl.arizona.edu>
To: <meteorite-list at meteoritecentral.com>; "Meteorites USA"
<eric at meteoritesusa.com>
Sent: Thursday, April 14, 2011 12:40 AM
Subject: Re: [meteorite-list] Space Radar?


> --- On Wed, 4/13/11, Meteorites USA <eric at meteoritesusa.com> wrote:
>
> > From: Meteorites USA <eric at meteoritesusa.com>
> > Subject: Re: [meteorite-list] Space Radar? (Was: Cold Asteroids May
> > Have A
> Soft Heart)
> > To: meteorite-list at 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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Received on Thu 14 Apr 2011 02:35:34 AM PDT