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Re: AMSAT HEO design evolution (longish)



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 
"HEO-projects"
like Phase-3 belong to the past century and just...  we don't want to accept 
it.
The money cost is unbelievable high.  Definitely is necessary to re-assign 
the
"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
Satellite
community by offering DX + overseas QSOs.

73, Mak SV1BSX


----- Original Message ----- 
From: <G0MRF@aol.com>
To: <m5aka@yahoo.co.uk>; <amsat-bb@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
> ask
> some fundamental questions about the way we design  satellites and fund
> their
> launch.
>
> The problem:  AMSAT High Earth Orbiting satellites have historically  had
> a
> 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
> million
> (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
> say
> 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
> approach
> 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
> project
> currently being persued is  the ESA ESEO educational mission with AMSAT UK
> providing
> a U/S transponder as  part of a redundant communications system for the
> spacecraft.
> 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
> NA
> board who have an apparently impossible task to fulfil, but their
> enthusiasm  to
> elicit support has let expectations exceed funding ability. - The response
> ha
> s been vocal. But at least they are trying.
> Finally on the funding issue, what have we done in the last 8 years?
> We've
> had the Eagle fund. We've had the successful AO-51 fund raising campaign,
> but
> really, since the launch of AO-40 in November 2000 we haven't  saved for
> this
> 'HEO' eventuality. If we are ever going to replace spacecraft in  the
> future,
> fund raising needs to be more sustained and less impulse led. We  have
> little
> 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
> substantially.
> 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
> those
> satellites have still given us usable communications. Do we  need all
> 60kg?
> How about raising the perigee to give a long life and  a slight increase
> in
> inclination to get us out of the GTO belt around from  around 7 degrees to
> 15
> degrees?   I wonder what the saving is there,  400 Newton motor down to 50
> Newton
> motor. Fuel from 60kg down to  15kg?  Saving = 45 + 5kg  = 1.5 million
> Euros?
> 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
> a
> 300 Watt BLF278 type device and was designed to give a huge signal.
> Equally,
> I  also recall receiving a worked all continents satellite award for QSOs
> I
> 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
> power
> in a  100kHz wide transponder? After all, if there are fewer amateurs, we
> can
> 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
> unreasonable,
> 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
> into
> 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
> stationkeeping
> 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
> them,
> 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
> satellite
> go through a couple of eclipses a day. As battery life is proportional
> (or
> worse) to depth of discharge of the batteries, it's not surprising that
> most
> AMSAT spacecraft suffer battery failure. But with limited funds we really
> need
> to design in a mode so that 5 years on, the batteries can be switched out
> of
> circuit and a sensible geometry of solar panels can continue to provide
> some
> daylight only functionality.
>
> Conclusion:
> 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
> spacecraft
> is better than no spacecraft at all.
>
> Thanks..........a quiet day here!
>
> David
>
> Could we do HEO within a 50kg budget?  = 1.5million Euros spread over  a
> 10
> year lifespan?
>
>
>
>
>
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