[amsat-bb] Re: AMSAT HEO design evolution (longish)
sv1bsx at yahoo.gr
Mon Aug 11 14:06:38 PDT 2008
Hi David, Hi all,
I found your statement very logical and I agree with you. Definitely we must
be more "flexible" in the new era and no "glued". Probably the
like Phase-3 belong to the past century and just... we don't want to accept
The money cost is unbelievable high. Definitely is necessary to re-assign
"HEO's concept" according to the currently & future era.
However, in addition to your Email I would like to remind that:
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) where
described the possibility for a MEO OSCAR, by using a small propellant
system onboard in order to be able to put the satellite higher than any LEO.
Thus the launching-cost should be very reasonable - even nowadays.
I don't know if that is possible in practice - I am not an expert about
that! However sounds to me as a great challenge for Ham radio, if a new
kind of Satellite-orbit could be available for Amateur Radio operators
If we can't to put a HEO in orbit, why not a MEO? The footprint is
spectacular vis-a-vis to a LEO.
Not like a HEO, but good enough in order to keep "warm" the Amateur
community by offering DX + overseas QSOs.
73, Mak SV1BSX
----- Original Message -----
From: <G0MRF at aol.com>
To: <m5aka at yahoo.co.uk>; <amsat-bb at amsat.org>
Sent: Monday, August 11, 2008 8:00 PM
Subject: [amsat-bb] AMSAT HEO design evolution (longish)
> Given the understandable negative content of the posts recently regarding
> the AMSAT HEO satellite debate, perhaps it's time to return to basics and
> some fundamental questions about the way we design satellites and fund
> The problem: AMSAT High Earth Orbiting satellites have historically had
> mass between 150kg for P3 and 650kg+ for AO-40 and at 30,000 Euros per
> kg, we
> do not have the resources to self finance the launch costs of 4.5
> (30k x 150) to 15 million Euros to launch.
> However, AO-40 was probably a 1-off and will never be repeated. So let's
> 4 - 5 million.
> The way forward?
> 1) Raising the funds for the standard launch cost of the typical AMSAT HEO
> is beyond us. So other external funding solutions are needed either by
> providing a service which is paid for. - An example of exploring this
> route is the
> AMSAT NA proposed Advanced Communications Project via Intelsat.
> A second approach, is to include commercial payloads within the AMSAT
> spacecraft, or perhaps including AMSAT 'functionality' within other
> commercially or
> educationally funded spacecraft. Again, there are examples of this
> for LEOs. Delfi C3 is one success story. Also, and had it worked for more
> than a few orbits the ESA Education department / SSETI Express XO-53 was
> another. But at HEO the opportunites are very rare indeed, the only
> currently being persued is the ESA ESEO educational mission with AMSAT UK
> a U/S transponder as part of a redundant communications system for the
> As we have been reminded in the past few days, self funding never worked
> before and it wont work in the future. I feel some sympathy for the AMSAT
> board who have an apparently impossible task to fulfil, but their
> enthusiasm to
> elicit support has let expectations exceed funding ability. - The response
> s been vocal. But at least they are trying.
> Finally on the funding issue, what have we done in the last 8 years?
> had the Eagle fund. We've had the successful AO-51 fund raising campaign,
> really, since the launch of AO-40 in November 2000 we haven't saved for
> 'HEO' eventuality. If we are ever going to replace spacecraft in the
> fund raising needs to be more sustained and less impulse led. We have
> to show for the last 8 years.
> 2) There is however another option which may be self financing. A
> fundamental spacecraft redesign to reduce the mass to a figure we can
> afford to launch.
> Over the last 25 years, the mass of a P3 spacecraft has remained fairly
> constant. About 90kg of structure and payload with an additional 60kg of
> bi-propellent fuel. There are probably ways of trimming this back
> In LEO sat design we have seen a reduction in size from 400kg to the SSTL
> microsat of about 120kg in the 1980's. These days the SSTL 'microsat' has
> evolved down to 3 - 5kg. with projects like the NASA Nanosail design. But
> no such
> revolution has taken place in HEO satellites
> So, a few possibilities. You can probably think of more......
> a) The 60kg of fuel has been needed to raise perigee and increase
> inclination from a typical geostationary transfer orbit. But there have
> been orbital
> change manoeuvres that have not gone to plan e.g. AO-10 and AO-40, but
> satellites have still given us usable communications. Do we need all
> How about raising the perigee to give a long life and a slight increase
> inclination to get us out of the GTO belt around from around 7 degrees to
> degrees? I wonder what the saving is there, 400 Newton motor down to 50
> motor. Fuel from 60kg down to 15kg? Saving = 45 + 5kg = 1.5 million
> OK the figures are guesswork, but there must be savings.
> b) Spacecraft design. During our time with P3 spacecraft, we have seen
> transponder power change dramatically. I recall the first few days of
> AO-40 when I
> heard the 2m beacon stronger than many local FM stations. But then it used
> 300 Watt BLF278 type device and was designed to give a huge signal.
> I also recall receiving a worked all continents satellite award for QSOs
> made on the experimental AO-13 mode S transponder. That was 1 Watt (max)
> into a
> 5 turn helix on 2400. So, in the future, do we need 45 or 50 Watts of
> in a 100kHz wide transponder? After all, if there are fewer amateurs, we
> use less bandwidth saving power and mass in the process. 8 Watts and
> 50kHz? A consequence of such a design change would require a
> groundstation with
> more than a patch antenna to pick up the signal. But is that
> dishes are cheaper than launches.
> c) Two final thoughts. Firstly, isn't the world moving away from metal
> structures to carbon and ceramic composites. Mass saving perhaps.
> Secondly, I
> don't think AMSAT with it's limited resources can afford to put spacecraft
> orbit that will fail the moment the batteries die. Let's not dwell on the
> excellent Delfi example, but instead look at the Intelsat spacecraft. Is
> it not
> the case that they have a 10 year lifespan which is limited by
> fuel? While they operate 24/7 the power comes from the solar cells. The
> batteries are used only in eclipse. With our P3 designs, as I understand
> the spacecraft can not function on solar cells alone. Unfortunately, the
> advantage of our chosen HEO orbits also mean that the batteries on a P3
> go through a couple of eclipses a day. As battery life is proportional
> worse) to depth of discharge of the batteries, it's not surprising that
> AMSAT spacecraft suffer battery failure. But with limited funds we really
> to design in a mode so that 5 years on, the batteries can be switched out
> circuit and a sensible geometry of solar panels can continue to provide
> daylight only functionality.
> Funding campaigns need to run over several years within a rolling plan to
> supply launch funding.
> Designs need to evolve to include new technologies. Mass reduction = lower
> launch cost should be near the top of the list.
> With fewer amateurs, and modern digital modes we need less bandwidth.
> It is not unreasonable for an AMSAT member to need a moderate size of
> antenna to work an HEO. So, lower power in space.
> Lifespan needs to be increased and with HEO that means battery failure
> should be anticipated and mitigated in the design. A daylight operating
> is better than no spacecraft at all.
> Thanks..........a quiet day here!
> Could we do HEO within a 50kg budget? = 1.5million Euros spread over a
> year lifespan?
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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