15 Oct
2009
15 Oct
'09
6:12 a.m.
Can't we just ask one of the guys on the ISS to lean out of the window, take a quick pic with his Canon Snappy as it comes round and then e-mail it to us ? :-D
--
David
KG4ZLB
www.kg4zlb.com
Tim - N3TL wrote:
> Please see Page 19 of the May-June 2008 issue of The AMSAT Journal.
>
> Patrick Seitzer, WA4DSR, provided a photo of AO-40 taken by the University of Michigan's Curtis-Schmidt Telescope at Cerro Tololo Inter-American Observatory in Chile. Following is information from a University of Michigan Web page about the telescope:
>
> "The Curtis-Schmidt telescope is a 0.61 meter aperture f/3.5 Schmidt telescope located at the Cerro Tololo Inter-American Observatory, about 500 km north of Santiago, Chile. This telescope was originally installed at the University of Michigan's Portage Lake Observatory in 1950, and moved to the much clearer skies of north central Chile in 1966.
> It is named for Heber D. Curtis, Director of the University of Michigan Observatories from 1930 until 1942.
> The telescope is dedicated to optical studies of artificial space debris for NASA's Orbital Debris Program Office at the Johnson Space Center. Projects include optical surveys for debris and follow-up observations to determine orbits and photometric properties of recently discovered debris."
>
> If you find the Journal photo, you'll see a field with dozens of blurred stars and one sharp litttle white dot, which is AO-40. I believe it's safe to say that obtaining an image with the detail necessary to try assess damage is impossible.
>
> 73 to all,
>
> Tim - N3TL
>
>
>
>
> ________________________________
> From: Mark VandeWettering [email protected]
> To: [email protected]
> Sent: Thursday, October 15, 2009 2:57:40 AM
> Subject: [amsat-bb] On the possibility of imaging AO-40 with earth bound telescopes...
>
>
>
> It's not going to work. AO-40 just isn't big enough. For fun,
> let's worth through
> some of the details.
>
>
>
>
>
>
>
> Table 1. Nominal Orbit Parameters for AO-40
> Orbit Parameter Value
> Semimajor Axis (km) 36,245
> Perigee Height (km) 1,042
> Apogee Height (km) 58,691
> Eccentricity 0.797
> Inclination (deg) 6.04
> Period (hours) 19.1
>
> Let's look at a couple of potential telescopes. The short tube
> refractor that you linked to has an 80 mm (roughly 3 inch) aperature.
> According to the Rayleigh criterion, that scope should be able to
> resolve angles as small as about 1.5 arc seconds. At perigee, the
> resolving power is 1042000 * tan(1.5 arc seconds), or about 7.5 meters
> (or 25 feet). To increase the resolution by a factor of 2, you need
> to to double the aperature. To get resolutions down to 1/2 a foot,
> you need an aperature 50x larger, or 150 inches.
>
> This doesn't take into account any effects of atmosphere either.
> it's actually fairly rare to get sub arcsecond resolution from any
> earthbound telescope without using adaptive optics.. This limits the
> practicality of high resolution imaging.
>
> Impressive photos of the space shuttle, ISS and HST have been taken
> using amateur equipment, but these objects are both closer and an
> order of magnitude larger than AO-40. While we might be able to
> measure spin rate and the like by measuring the brightness curve,
> actual imaging of the satellite isn't likely.
>
> 73 Mark K6HX
> _______________________________________________
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> _______________________________________________
> Sent via [email protected]. Opinions expressed are those of the author.
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>
>