I agree with much of what Dan, N8GFV, says. Our best hope of a high altitude
satellite is probably a hosted payload on a GEO sat. To make that viable we
need to consider the entire mission. GEO satellite operators are a for-profit
business and every aspect of a commercial satellite has a dollar value. The
major items are spectrum, power and fuel. Since hams bring their own spectrum,
that is a no cost item for us. If we need to use satellite power then we would
need to pay the market rate for the percentage of the total satellite resource
used for the design lifetime of the satellite, typically 15 years. If the
payload can be disabled by the operator we may be able to negotiate a pay as
you go plan so that we don't have to pre-pay 15 years worth of power.
Developing very power efficient transponder systems will reduce our costs.
Trading bandwidth for power by using digital encoding, strong FEC, regenerative
transponders with DSP signal enhancement will all aid in the reductio!
n of the power required to close a link.
The other big cost factor is fuel. As previously stated here, station keeping
is a critical element in GEO satellites and with the advances of component
technology, a satellites lifetime in orbit is determined primarily by the
amount of station keeping fuel it can carry. The more fuel, the longer the
satellite life, the more time the operator can use to recover their investment
and make money. Every ounce added to the satellite affects the cost of the
launch and possibly the amount of fuel that can be carried on board. Whether
this is the case or not, the added satellite weight WILL add to the launch cost
that we would have to pay.
The good news is that the AMSAT community and the satellite operators have
common interests in making satellites less expensive and more efficient. By
building on the technology pioneered in ARISSAT-1 we MAY be able to get some
cooperation from a commercial operator to deploy a technology demonstration
package as a hosted payload. This might be more probable than one thinks.
Satellite operators are EXTREMELY conservative and don't deploy new technology
until it is thoroughly proven. The commercial satellite market is running out
of real estate. Many of the big operators are at over 80% capacity. Since they
are for-profit organizations, they are running out of product quickly and will
not be able to grow their business. All the major operators are investing large
amounts of money to promote a hosted payload business where government and
scientific users can bring their own bandwidth to a transponder or payload on
the operators platform. A low cost, high performance, innovativ!
e payload COULD be a great advertising tool for a commercial operator. The
operator would get the payload for zero cost and could also get part of the
launch cost subsidized by AMSAT in return for a real world, open source
demonstration tool.
If we build this payload along the lines of Tom Clark's C-C rider concept with
a 5 GHz up/ 3 GHz. down transponder we can probably even use the satellites low
gain telemetry antenna, further reducing payload costs.
Sorry for the lengthy post but I have been thinking about this for a while and
this seemed like a good opportunity to finally put it in writing.
HowieAB2S
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