Pegasus/SciSat Launch Cost

(Allen Thomson) wrote:
That's correct, (AFAIK, also). Several years ago some people interested
in missile proliferation (I think it was the CHOP operation at Kirtland)
looked into this and found that the altitude/velocity limitations in
a number of commercial GPS systems were implemented in the display
drivers, not the GPS engines themselves.

Ick. As I understood it, they were supposed to be locked out in the
engines.

D.
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Ian Stirling wrote:
For the pretty fundamental reason that you've got to have a position
solution in order to work out if you should blank the display...
(well, there are some limits, but only well above the posted limits)

Um, no.

If the GPS engine knows there are limits, it obviously knows they are
being exceeded, and refuses to send the data to the display.

There is nothing fundemental about the blanking being done in the
display vice the engine.

D.
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Derek Lyons wrote:
Ian Stirling wrote:
For the pretty fundamental reason that you've got to have a position
solution in order to work out if you should blank the display...
(well, there are some limits, but only well above the posted limits)

Um, no.

If the GPS engine knows there are limits, it obviously knows they are
being exceeded, and refuses to send the data to the display.

True, if they are seperate.
There is often one microprocessor doing both the display driving, and the
decoding of the GPS signal, hooked to the GPS reciever circuitry and the LCD.
The reciever may do lots of signal processing, but probably won't go all the
way to a position, as it's designed under the assumption there will be a micro
somewhere in the system.
Any limits from the reciever will typically be due to design limitations,
such as loop stability/noise tradeoffs which give jerk limits, and VCO
range which gives velocity limits.

However, the velocity limits are with respect to the satellites, and if
you are willing to ignore the ones you are moving away from, commercial
recievers pretty much have to be able to cope with the 2000m/s (?) of
relative motion, plus the ~500m/s of the artificial speed limit, for a
total of 2500m/s.
If you'r going towards a satellite going away from you, then you'll probably
get a usable position up till well over 4Km/s.

There is nothing fundemental about the blanking being done in the
display vice the engine.

Fundamental, no, but the economics tend to imply it for most of the chipsets
I've looked at.
You don't want to add a seperate micro just to do position calculation and
pass it to a display micro.
(for small GPS units, for really expensive ones where the display may be
a much harder and more expensive task than the GPS decoding things may
change)

--
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---------------------------+-------------------------+--------------------------
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"Colonel K" wrote in message om...
"Alex Terrell" wrote in message
om...
I think a lot of the above (not all) could be digitised, which would
reduce cost and improve reliability. For telemetary transmitters,
modify a satellite phone.

You're silly.

Your wit knows no bounds.

Please explain what elements of telemetary cannot use a modified satellite phone.

If launch costs were lower, people would design cheaper, less relaible
satellites. Increased volume would again push the price down).

Tremendously doubtful.

Why spend $300 million on a comsat if I can launch it for $5 million?

"Alex Terrell" wrote in message
om...
"Colonel K" wrote in message
om...
"Alex Terrell" wrote in message
om...
I think a lot of the above (not all) could be digitised, which would
reduce cost and improve reliability. For telemetary transmitters,
modify a satellite phone.

You're silly.

Your wit knows no bounds.

Thank you (takes a bow).

Please explain what elements of telemetary cannot use a modified satellite
phone.

I'd like to see you qualify a satellite telephone for the job you just
specified. It'd be cheaper and more reliable to use the products available
now.

If launch costs were lower, people would design cheaper, less relaible
satellites. Increased volume would again push the price down).

Tremendously doubtful.

Why spend $300 million on a comsat if I can launch it for $5 million?

Because that $300M buys a tremendous amount of long-lived capability. The
launch price is not a factor in the equation. Quality and reliability of
service to customers is.

-Colonel K

"Colonel K" wrote:

"Derek Lyons" wrote in message
...
AFAIK there are no GPS receivers outside of government hands that will
perform in an accelerating booster. (There are hard limits inside
commercial chips specifically to prevent provide cheap guidance
systems to folks we'd rather not have.)

OSC buys a COTS GPS unit for Pegasus. It's built by Honeywell and called
SIGI - Space Integrated GPS/INS.

http://www.ais.honeywell.com/dss/sgp...ts/gn-sigi.htm

COTS does not mean anyone can walk in off the street and by them. It
merely means that it is not a specially designed item. (It
specifically does not mean an item in serial production.)

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

Text-Only Version:
http://www.io.com/~o_m/columbia_loss_faq.html

Enhanced HTML Version:
http://www.io.com/~o_m/columbia_loss_faq_x.html

Corrections, comments, and additions should be
e-mailed to , as well as posted to
sci.space.history and sci.space.shuttle for
discussion.

"Derek Lyons" wrote in message
...
COTS does not mean anyone can walk in off the street and by them. It
merely means that it is not a specially designed item. (It
specifically does not mean an item in serial production.)

If you are a commercial customer and meet the criteria (a valid peaceful use
for the device) you can buy one. In aerospace, that's COTS. If your idea of
COTS means buying it at Radio Shack, then you should rethink your
definition.

-Colonel K

"Colonel K" wrote

"Derek Lyons" wrote

COTS does not mean anyone can walk in off the street and by them. It
merely means that it is not a specially designed item. (It
specifically does not mean an item in serial production.)

If you are a commercial customer and meet the criteria (a valid peaceful use
for the device) you can buy one. In aerospace, that's COTS. If your idea of
COTS means buying it at Radio Shack, then you should rethink your
definition.


True and true. It is, however, an interesting and sometimes
instructive exercise to see what you *can* build (or at least
design) using no-fooling, walk-in-and-buy-it equipment.

(Allen Thomson) :

"Colonel K" wrote

"Derek Lyons" wrote

COTS does not mean anyone can walk in off the street and by them. It
merely means that it is not a specially designed item. (It
specifically does not mean an item in serial production.)

If you are a commercial customer and meet the criteria (a valid peaceful
use
for the device) you can buy one. In aerospace, that's COTS. If your idea
of
COTS means buying it at Radio Shack, then you should rethink your
definition.


True and true. It is, however, an interesting and sometimes
instructive exercise to see what you *can* build (or at least
design) using no-fooling, walk-in-and-buy-it equipment.

For COTS I find my biggest problem is finding the correct supplier. Right
now I am looking for a small all stainless-steel or all alumium rotary vane
pump, just the pump - no motor - I need to pump low pressure H2O2 vapours.
So far I have hit over a hundred online catalogs and called half a dozens
local suppliers. No luck so far, I know such exist as the big industrial
ones do, but all the companies I have called said they don't have any or any
that small. I am also not sure the person at Fisher Science understood me
right and may think they don't have something that infact they do have. And
don't let me get in how bad *SOME* online catalogs are organized, some are
missing critcal hyperlinks to needed data, but one site I was on *ALL* the
hyperlinks only point to the same useless pages. Plus too many just point to
thier sales force, I hate having to explain what I am doing to a saleman who
often has no engineering background, he (usually) get lost the moment you
leave the pre-planned sales script.

Earl Colby Pottinger
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In article ,
ed kyle wrote:
That's $144,000 per kg! ... The spacecraft/mission
cost seems quite reasonable by comparison. (Maybe Canada
should develop its own space launcher, eh?)

Believe me, some of us have thought about it. :-) Really hard to get the
Canadian government to fund it, however. Partly there's an ingrained
inferiority complex, a belief that Canada couldn't *possibly* do something
that daring all by itself, so anyone who tries to sell Canada on it must
be a con man. Partly there was a strategic decision made several decades
ago that Canada would not build its own launchers, and whether or not the
old reasons still apply, it has attained the status of religious dogma in
the funding agencies -- even propulsion research tends to be dismissed as
something that Canada Just Doesn't Do. Sigh.
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