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CX2SA > SATDIG 12.08.08 01:59l 772 Lines 27920 Bytes #999 (0) @ WW
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Today's Topics:
1. DO-64 observation (Luc Leblanc)
2. Re: [eu-amsat] AMSAT UK P3E Lecture Available (Joe Westbrook)
3. Searching for Az/El Rotor (iz1dsj(AT)sparks.it)
4. Re: Fw: Re: [eu-amsat] AMSAT UK P3E Lecture Available
(Luc Leblanc)
5. Re: WD9EWK's first non-FM satellite QSOs today! (K & R Yoksh)
6. Re: WD9EWK now on VO-52! (i8cvs)
7. Re: WD9EWK now on VO-52! (Alan P. Biddle)
8. Re: WD9EWK's first non-FM satellite QSOs today!
(n3tl(AT)bellsouth.net)
9. Re: DO-64 observation (wouter weggelaar)
10. Re: Delfi-C3 (wouter weggelaar)
11. AMSAT HEO design evolution (longish) (G0MRF(AT)aol.com)
12. Re: DO-64 observation (Rick Mann)
----------------------------------------------------------------------
Message: 1
Date: Sun, 10 Aug 2008 11:58:35 -0400
From: Luc Leblanc <lucleblanc6(AT)videotron.ca>
Subject: [amsat-bb] DO-64 observation
To: info(AT)delfic3.nl
Cc: amsat-bb(AT)AMSAT.Org, eu-amsat(AT)yahoogroups.com
Message-ID: <489ED7EB.19583.BA63C2(AT)lucleblanc6.videotron.ca>
Content-Type: text/plain; charset=US-ASCII
First experience with do-61 (DELFI C-3) this morning here.
1-No body was on the satellite only me calling CQ
2-From AOS to TCA signal was very good about +-3 DB above noise level
3-At TCA signal dropped below noise level too week for SSB but week for CW
4-From TCA to LOS signal remain below noise level and became too weak even for
CW
I suspect the satellite antenna configuration show some directivity or it is
the satellite attitude who seems to favour some part of the
orbit pass? I was never able to received my SSB dowlink on the eastern pass
only a week CW carrier one time. There is some audio AGC as
increasing the audio level make's not a big change on the dowlink. I was able
to uplink with the FT-847 RF gain control completely turned
off (about 1 or 2 watts).
I don't know if my results are in line with what the team planned but when the
sat was on data mode i was able to copy it from AOS to LOS
but i think the TX power is reduced in transponder mode?
It make's another one to experiment with and a preamp is imperative to be able
to work it with ease. Just have to get some folk's on it
here to be able to check it again.
"-"
Luc Leblanc VE2DWE
Skype VE2DWE
www.qsl.net/ve2dwe
WAC BASIC CW PHONE SATELLITE
------------------------------
Message: 2
Date: Sun, 10 Aug 2008 11:32:09 -0500
From: "Joe Westbrook" <k7zt(AT)suddenlink.net>
Subject: [amsat-bb] Re: [eu-amsat] AMSAT UK P3E Lecture Available
To: "John B. Stephensen" <kd6ozh(AT)comcast.net>, "Luc Leblanc"
<lucleblanc6(AT)videotron.ca>, <eu-amsat(AT)yahoogroups.com>
Cc: amsat-bb(AT)amsat.org
Message-ID: <001501c8fb06$a2b18e60$0302a8c0(AT)corp.global.level3.com>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
John:
Yes, you may have heard statements like in the past we've relied on charity,
and Amateur Radio Operators alone can not fund a launch, what you haven't
heard are any solutions for launching any HEOs. It seems that the DL folks
haven't lost that as a focus, they acknowledge that as expensive as it is to
launch an HEO, it is still doable. 3 - 4M Euros $4 - 5M at least they gave
us a tangible figure we can work with. This amount may be a reach for
AMSAT-NA alone, but given that we finally understand what it would take to
make a HEO Launch reality, then why wouldn't we shift ALL funding toward
that effort? Following the PE3 launch, if any surplus remains, the
surplus could be transferred to the next HEO opportunity (Eagle). If no
surplus remains then at least we would have one working HEO deployed.
Additionally, at least we know the PE3 platform is well vetted, and would
have the lowest risk. Rather than spending time and resources on a new,
untested platform why wouldn't we just facilitate PE3 FIRST?
Ok, I'll speech for myself here, but the GEO ride-share simply isn't an
opportunity that will interest the HEO crowd. Launching an appliance to
serve the disaster response community and entry level satellite users won't
do a thing to satisfy the need for a HEO. I don't care if it's free, like
AO51, I would probably get on it, make a couple contacts say "that's nice"
and be done with it. Please understand, I'm not saying to abandon GEO as a
viable option, just don't spend a cent on it until we launch an HEO.
What we need is a satellite that enables the real sprit and intent of the
Amateur Radio Service, to push the envelop of the technology, allow for
experimentation, consider all of the alternative antenna solutions that our
resourceful community developed to receive the 2.4Gig Down Link. No rotator
required, different feed systems, a fairly modest resource outlay to get on
the air. I did it with a totally home brewed system in a restricted
neighborhood back yard. Had a blast and learned allot.
----- Original Message -----
From: "John B. Stephensen" <kd6ozh(AT)comcast.net>
To: "Luc Leblanc" <lucleblanc6(AT)videotron.ca>; <eu-amsat(AT)yahoogroups.com>
Cc: <amsat-bb(AT)amsat.org>
Sent: Friday, August 08, 2008 3:14 PM
Subject: [amsat-bb] Re: [eu-amsat] AMSAT UK P3E Lecture Available
> I've been hearing these two statments from AMSAT-NA officals for at least
> 2
> years -- in person and on this BB.
>
> 73,
>
> John
> KD6OZH
>
> ----- Original Message -----
> From: "Luc Leblanc" <lucleblanc6(AT)videotron.ca>
>>
>> Very nice presentations. One attract my attention was made by Peter
>> Guelzow DB2OS one one of his slide we can read:
>>
>> ATTRACTIVENESS OF AMATEUR RADIO HAS DROPPED SIGNIFICANTLY
>>
>> FUNDING A SATELLITE FROM AMATEUR RESSOURCES ALONE NEVER WORKED BEFORE AND
>> WILL NOT WORK NOW.
>>
>> I don't how to explain how all the wisdom and reality knowledge seems to
>> be concentrated in Europe when speaking about amateur satellite?
>
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 3
Date: Sun, 10 Aug 2008 20:31:40 +0200 (CEST)
From: iz1dsj(AT)sparks.it
Subject: [amsat-bb] Searching for Az/El Rotor
To: Amsat-bb(AT)amsat.org
Message-ID: <3017.77.54.14.52.1218393100.squirrel(AT)webmail.comm.cc>
Content-Type: text/plain;charset=iso-8859-1
While on holiday I started planning a sat station, so I'm searching for an
used Yaesu 5400/5500/5600 rotor system.
If somebody wants to sell his one, possibly in Europe (coustoms and
shipping would be less expensive), contact me, otherwise in September will
buy a new one :( Hi!
Thanks.
IZ1DSJ Jack (iz1dsj(AT)sparks.it)
------------------------------
Message: 4
Date: Sun, 10 Aug 2008 20:43:13 -0400
From: Luc Leblanc <lucleblanc6(AT)videotron.ca>
Subject: [amsat-bb] Re: Fw: Re: [eu-amsat] AMSAT UK P3E Lecture
Available
To: amsat-bb(AT)AMSAT.Org
Cc: eu-amsat(AT)yahoogroups.com
Message-ID: <489F52E1.19130.29AB917(AT)lucleblanc6.videotron.ca>
Content-Type: text/plain; charset=US-ASCII
On 11 Aug 2008 at 9:02, Tim Tuck wrote:
> Trevor wrote:
>
> > Off the top of my
> > head I can only think of three AMSAT groups that have more than 100
members,
> > AMSAT-NA, AMSAT-UK and AMSAT-DL. (I really would love to be proved wrong
on
> > that).
> >
>
> AMSAT-VK currently has 159 members at last count. We're very active on the
LEO's
> down here and many of us are actively recruiting members.
>
> More info at...
> http://au.groups.yahoo.com/group/amsatvk/
>
> cheers
>
> Tim
>
>
> --
>
> VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT-VK :: AMSAT
>
>
After all it seems some here are also running for WISDOM but i'm could be a
bit over optimistic when i throw the 6000 sat fans i was
probably induced in error by Paris Hilton fans group? It remain a fact that 2
groups having the same funding issues prefer to follow their
own same satellite project?
BTW She's 40 years old and she never know where to send her money? Did any one
ever think if she can help our cause? It could be sound
foolish but thinking twice it could be not so foolish after all...
"-"
Luc Leblanc VE2DWE
Skype VE2DWE
www.qsl.net/ve2dwe
WAC BASIC CW PHONE SATELLITE
------------------------------
Message: 5
Date: Mon, 11 Aug 2008 01:23:41 -0500
From: "K & R Yoksh" <yokshs(AT)sbcglobal.net>
Subject: [amsat-bb] Re: WD9EWK's first non-FM satellite QSOs today!
To: <amsat-bb(AT)amsat.org>
Message-ID: <002201c8fb7a$cd822720$6401a8c0(AT)MAIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Clint Bradford said:
> lo and behold, Athens, Georgia's own N3TL came through. It was a 4.1
> degree of elevation pass for him. Let me repeat
> that, in case you thought there was a typo: FOUR POINT ONE DEGREES OF
> ELEVATION for Tim in Georgia. But he
> was cheating: he was using a full five Watts output on his Yaesu FT-60. I
> refuse to use high power during my demos...(grin)
N3TL has gone QRO!?! <grin> I worked him the other day on AO-51 when was
using 50 mW!
73.
Kyle Yoksh
K0KN
Olathe, Kansas
------------------------------
Message: 6
Date: Mon, 11 Aug 2008 12:10:21 +0200
From: "i8cvs" <domenico.i8cvs(AT)tin.it>
Subject: [amsat-bb] Re: WD9EWK now on VO-52!
To: <amsat-bb(AT)wd9ewk.net>, "AMSAT-BB" <amsat-bb(AT)amsat.org>
Message-ID: <001d01c8fb9a$77b2c8c0$0201a8c0(AT)tin.it>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Patrick STODDARD (WD9EWK/VA7EWK)" <amsat-bb(AT)wd9ewk.net>
To: <amsat-bb(AT)amsat.org>
Sent: Monday, August 11, 2008 5:20 AM
Subject: [amsat-bb] WD9EWK now on VO-52!
> Hi all!
snip
>
> I then planned to make one more attempt on FO-29 before returning
> to Phoenix this afternoon. I found a nice high (maximum elevation
> 75 degrees) pass at 1835-1851 UTC. I could hear the downlink about
> a minute or so into the pass, and could hear myself through FO-29
> shortly after that. Around the halfway point of the pass, I lost
> the downlink. I was not able to hear it for the remainder of the
> pass.
>
> My radios checked out OK, so now I need to take a look at my Yagi
> and coax. I had a coax issue crop up a few months ago, so that
> could be the problem. I have not read anything that would indicate
> a new problem on FO-29, and I'm hoping there are no problems with
> that satellite.
>
> Patrick WD9EWK/VA7EWK
> http://www.wd9ewk.net/
Hi Patrick, WD9EWK/VA7EWK
With FO-29 a low noise preamplifier antenna mounted is mandatory.
Actually FO-29 is working very well even in full eclipse here during
the night south-bound orbits.
When you are able to receive the CW beacon all the way during a whole
orbit then your receiving system is OK for it.
73" de
i8CVS Domenico
------------------------------
Message: 7
Date: Mon, 11 Aug 2008 05:55:55 -0500
From: "Alan P. Biddle" <APBIDDLE(AT)UNITED.NET>
Subject: [amsat-bb] Re: WD9EWK now on VO-52!
To: <amsat-bb(AT)amsat.org>
Message-ID: <31247B9079084386A0D52BF86BB09A33(AT)WA4SCA>
Content-Type: text/plain; charset="us-ascii"
Patrick,
How are they going to keep them down on the (FM) farm once they discover
SSB?!
73s and welcome!
Alan
WA4SCA
------------------------------
Message: 8
Date: Mon, 11 Aug 2008 12:48:42 +0000
From: n3tl(AT)bellsouth.net
Subject: [amsat-bb] Re: WD9EWK's first non-FM satellite QSOs today!
To: "K & R Yoksh" <yokshs(AT)sbcglobal.net>, <amsat-bb(AT)amsat.org>
Message-ID:
<081120081248.12961.48A03529000F0F6F000032A122243651029B0A02D2089B9A019C
04040A0DBF049BCC02(AT)att.net>
Content-Type: text/plain; charset="utf-8"
QRO again, indeed!
There was a reason for the "Duracell experiment" here in northeast Georgia. I
started out just wanting to see whether I could work any of the three Mode-J
satellites on "flea power," as Rick, WA4NVM, has dubbed it. Back on July 8th,
I put a fresh set of two AA Duracells in the BCA-23 battery case for my Yaesu
VX-7R HT, and replaced the standard rechargeable battery pack with it. On
alkalines, the radio wlll operate either at 300 mW RF out or 50 mW RF out.
I worked a few stations on 300 mW, then decided to see what I could do on 50
mW. Four states and Ontario later, I realized there was an opportunity here to
indulge my addiction to QRP!
I switched back to the rechargeable pack and ran full power - 5 watts into an
Arrow handheld yagi - for a couple more weeks before deciding to launch the
"Duracell experiment" full-on. From July 31 through Aug.3, I operated
exclusively on Duracells running 50mW RF out. At 13:58 UTC on Aug. 3, I was
thrilled to make my first-ever contact with W1AW (any band, any mode) - via
AO-51 - with Mark, WA8SME, at the controls up there. That contact also gave me
the last one I needed to apply for (subject to receiving all the QSL cards, of
course) the AMSAT Satellite Communications Achievement Award using ALL 50 mW
contacts, and on the SAME SET of Duracells!
I worked Mark again on Aug. 5 - during a demo he was doing for teachers - on
50mW RF out. I was able to squeeze one more contact out of those batteries -
with K4DLG in Florida, the next day. In all, I made 50 contacts on 50 mW RF
out and three contacts on 300 mW RF out on those two Duracells, with stations
in 20 states, Ontario, Mexico and Venezuela. I'm going to find a small, nice
piece of wood and mount those Duracells for display in my shack!
Kyle is one of the contacts whose card will be included in the AMSAT award
application. Thank you for that! And thanks to everyone who has worked so hard
to get all of our amateur satellites into orbit. I hope to join Patrick
(WD9EWK) on some of the other-mode satellites before too much longer.
73 to all,
Tim - N3TL
-------------- Original message from "K & R Yoksh" <yokshs(AT)sbcglobal.net>:
--------------
> Clint Bradford said:
>
> > lo and behold, Athens, Georgia's own N3TL came through. It was a 4.1
> > degree of elevation pass for him. Let me repeat
> > that, in case you thought there was a typo: FOUR POINT ONE DEGREES OF
> > ELEVATION for Tim in Georgia. But he
> > was cheating: he was using a full five Watts output on his Yaesu FT-60. I
> > refuse to use high power during my demos...(grin)
>
> N3TL has gone QRO!?! I worked him the other day on AO-51 when was
> using 50 mW!
>
> 73.
>
> Kyle Yoksh
> K0KN
> Olathe, Kansas
>
>
>
>
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
------------------------------
Message: 9
Date: Mon, 11 Aug 2008 15:12:56 +0200
From: "wouter weggelaar" <wouterweg(AT)gmail.com>
Subject: [amsat-bb] Re: DO-64 observation
To: "Luc Leblanc" <lucleblanc6(AT)videotron.ca>
Cc: amsat-bb(AT)amsat.org, info(AT)delfic3.nl, eu-amsat(AT)yahoogroups.com
Message-ID:
<7abd0e260808110612qd784f7dg561f49f9065e7e13(AT)mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi Luc,
Thanks for your report here on the BB,
Did you try to switch your polarization between LHCP and RHCP?
As Delfi-C3 goes over the earths poles, it flips itself 180 degrees in
Z axis (perpendicular to earth). Otherwise one side will be always
exposed to sunlight and things might run hot / degrade in time.
Due to this flip, the polarization sense changes depending on which
pass you are tracking (ascending from south to north, or descending
from north to south)
If you do not switch polarization sense, you can observe big
differences between those two.
Please bear in mind that Delfi does not have any active attitude
control system and solely relies on passive stabilization.
During a pass, polarization might change due to slow rotations. You
could try to switch polarization within a pass and see whichever is
stronger.
Delfi-C3 does have an RF AGC within the IF-stage, so uplinking more
power than necessary only limits other weaker stations and does not
improve your own signal.
We received some reports about people uplinking using a FT817 with
abt. 5 Watts into an arrow antenna, so your 1 or 2 watts with a good
antenna could do miracles...;)
Reports of Delfi-C3 (DO-64) transponder operation are greatly
appreciated and can be sent to info at delfic3.nl or via the BB.
On behalf of the Delfi-C3 team,
Best 73's
Wouter Weggelaar
PA3WEG
Delfi-C3 Command Team
On Sun, Aug 10, 2008 at 5:58 PM, Luc Leblanc <lucleblanc6(AT)videotron.ca>
wrote:
> First experience with do-61 (DELFI C-3) this morning here.
>
> 1-No body was on the satellite only me calling CQ
> 2-From AOS to TCA signal was very good about +-3 DB above noise level
> 3-At TCA signal dropped below noise level too week for SSB but week for CW
> 4-From TCA to LOS signal remain below noise level and became too weak even
for CW
>
> I suspect the satellite antenna configuration show some directivity or it is
the satellite attitude who seems to favour some part of the
> orbit pass? I was never able to received my SSB dowlink on the eastern pass
only a week CW carrier one time. There is some audio AGC as
> increasing the audio level make's not a big change on the dowlink. I was
able to uplink with the FT-847 RF gain control completely turned
> off (about 1 or 2 watts).
>
> I don't know if my results are in line with what the team planned but when
the sat was on data mode i was able to copy it from AOS to LOS
> but i think the TX power is reduced in transponder mode?
>
> It make's another one to experiment with and a preamp is imperative to be
able to work it with ease. Just have to get some folk's on it
> here to be able to check it again.
> "-"
>
>
> Luc Leblanc VE2DWE
> Skype VE2DWE
> www.qsl.net/ve2dwe
> WAC BASIC CW PHONE SATELLITE
>
>
>
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 10
Date: Mon, 11 Aug 2008 15:43:45 +0200
From: "wouter weggelaar" <wouterweg(AT)gmail.com>
Subject: [amsat-bb] Re: Delfi-C3
To: "WILLIAMS MICHAEL" <k9qho6762(AT)sbcglobal.net>
Cc: amsat-bb(AT)amsat.org
Message-ID:
<7abd0e260808110643p6fd1d048kda3435961fad7c41(AT)mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Mike,
Please read my reply to Luc Leblanc on the BB.
you can find this at:
http://www.amsat.org/pipermail/amsat-bb/2008-August/013142.html
Because Delfi has no active attitude control system, polarization might
change.
Switching polarization might help, but I understand this is not
possible for you.
You could try to figure out which passes work best for you.
Reports are appreciated!
Regards,
Wouter Weggelaar
PA3WEG
Delfi-C3 Command Team
On Mon, Aug 11, 2008 at 12:56 AM, WILLIAMS MICHAEL
<k9qho6762(AT)sbcglobal.net> wrote:
> I'm having trouble receiving DO-64.
>
> It seems to be strongest at the beginning of the pass and then gets weaker.
>
> What is the polarization of the up link and down link?
>
> I'm using a KLM 14 el LHCP for down link and 11 turn helix RHCP for up
link.
>
> When conditions are good (no local QRM) , I can hear AO7, VO-5, and FO-29
easily AOS/LOS even thought I have ground clutter up to about 20 degrees with
my antennas 8 ft. off the ground.
>
> I would be interested in how strong others are receiving DO-64 and at what
signal strengths.
>
> By the way, the beacon sounds stronger than the transponder signals.
>
> Tnx,
>
> Mike K9QHO
> AMSAT 33589
> _______________________________________________
> Sent via AMSAT-BB(AT)amsat.org. Opinions expressed are those of the author.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
------------------------------
Message: 11
Date: Mon, 11 Aug 2008 13:00:55 EDT
From: G0MRF(AT)aol.com
Subject: [amsat-bb] AMSAT HEO design evolution (longish)
To: m5aka(AT)yahoo.co.uk, amsat-bb(AT)amsat.org
Message-ID: <c85.32848160.35d1ca47(AT)aol.com>
Content-Type: text/plain; charset="US-ASCII"
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?
------------------------------
Message: 12
Date: Mon, 11 Aug 2008 11:50:47 -0700
From: Rick Mann <rmann(AT)latencyzero.com>
Subject: [amsat-bb] Re: DO-64 observation
To: wouter weggelaar <wouterweg(AT)gmail.com>
Cc: amsat Org <amsat-bb(AT)amsat.org>
Message-ID: <65F392B4-4ED5-4528-A8D1-D2E01630079A(AT)latencyzero.com>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
On Aug 11, 2008, at 06:12:56, wouter weggelaar wrote:
> As Delfi-C3 goes over the earths poles, it flips itself 180 degrees in
> Z axis (perpendicular to earth). Otherwise one side will be always
Are you saying it has an active attitude control that it uses to
change orientation right as it crosses the poles? Or is the satellite
rotating with a period equal to that of its orbit?
TIA,
--
Rick
------------------------------
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End of AMSAT-BB Digest, Vol 3, Issue 405
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