All the reasoning below is quite progressive. Thanks, everyone. If I can piggy-back on Trevor's suggestions, I suspect a cubesat-based collaboration with a university group that wants to try out a new propulsion scheme would be idea. We would offer our expertise in communications and antenna design and, more importantly, our telemetry-collecting strength-in-numbers. They would build the propulsion system, either ion-based, or sail, or whatever.
Consider that, for us, many kinds of failures of these sorts of propulsion systems would not be catastrophic: we'd just have another LEO at 700km to play with. Moreover, if the satellite took 2 years to reach its target altitude, I think we'd all find it great fun to watch and track that. Perhaps if it were a propulsion system like ion, that requires the use of the solar panels, we could periodically switch the propulsion off and try out the transponder to 'wet our whistles'.
Finally, this sort of scheme would be very nicely suited for S-band work, since the doppler shift would not be as painful with the higher altitude. With the lower altitude, but lower power, perhaps the 60cm dish could be used, thereby allowing a more easily camouflaged antenna set-up for US hams in restricted circumstances. (The uplink antenna is something of a problem, but perhaps 50w on 70cm into a attic-mounted beam would still do well.)
Nobody's mentioned attitude control yet. I assume that with a propulsion system attitude will have to be finely controlled. Is this a problem?
73, Bruce VE9QRP
On Mon, Aug 11, 2008 at 6:55 PM, Trevor m5aka@yahoo.co.uk wrote:
A MEO orbit at 4500 km would be good compromise between range, path loss, radiation, time delay and doppler shift but the problem is geting there or to higher MEOs. Inevitably you'd end up with a propulsion system on your sat to get from a 'cheap' 700 km orbit. But once you've got such a system the additional costs to get it into an HEO orbit are negligable.
However, as the web page http://www.g0mrf.freeserve.co.uk/MEOSAT.htm shows there are other propulsion systems that are feasable assuming you're prepared to wait longer to achieve the final orbit.
One of the great things about Cubesats is that they allow you to try experiments such as alternate means of achieving orbital changes at 'little' cost.
73 Trevor M5AKA
--- On Mon, 11/8/08, Graham Shirville g.shirville@btinternet.com wrote:
From: Graham Shirville g.shirville@btinternet.com Subject: Re: [amsat-bb] Re: AMSAT HEO design evolution (longish) To: "SV1BSX" sv1bsx@yahoo.gr, G0MRF@aol.com, m5aka@yahoo.co.uk, amsat-bb@amsat.org Date: Monday, 11 August, 2008, 10:29 PM
if we can not launch a HEO, why not about a MEO? I
remember a nice page
around Internet (unfortunately I can't find this
page any longer)
Try one of David's own pages:
http://www.g0mrf.freeserve.co.uk/MEOSAT.htm
Really interesting and thought provoking reading!
73
Graham G3VZV
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