A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Space Shuttle
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

National Space Policy: NSDD-42 (issued on July 4th, 1982)



 
 
Thread Tools Display Modes
  #62  
Old June 18th 04, 06:51 PM
Sander Vesik
external usenet poster
 
Posts: n/a
Default National Space Policy: NSDD-42 (issued on July 4th, 1982)

In sci.space.policy Scott M. Kozel wrote:

GPS is not "offensive space-based weaponry", and for you to assert that
it is, shows you have an agenda to post disinformation about the topic.


Fine. And I doubt many people would argue against that. But surely you
don't want to claim that specificly military tailored and military
controlled navigation satellites used in weapons targeting are part
not of space militarisation?

--
Sander

+++ Out of cheese error +++
  #63  
Old June 18th 04, 07:40 PM
Derek Lyons
external usenet poster
 
Posts: n/a
Default GPS Megadeath

Steven James Forsberg wrote:

: The problem with that is... We had no need of such a capability.
: What an SSBN needs is a method of knowing it's position *without*
: having to surface, or preferably even coming close to the surface. We
: already had that capability with SINS, SINS/ESGM, and with ESGN.
: From the point of view of an SSBN, GPS is 'nice-to-have', not 'must
: have'.

I'm not certain I quite agree with that.


You may do so. I'll refute as best I can without risking a
vacation in Kansas. (Do keep in mind I did this stuff for a living.)

The USN definitely needed such a capability. For starters, SSBNs launch
from relatively close to the surface, and in launching advertise themselves
very well, and are not supposed to be anywhere near an enemy when they
do. Thus, coming close to or at the surface is not such a liability.


SSBN's launch from considerably beneath periscope depth. Transiting
to PD and back to launch depth not only increases the length of the
launch process, but increases the 'something is up' signature. We
won't launch if we know we are being shadowed, but for obvious reasons
we always behave as if we are being shadowed and just don't know it.
Thus coming close to the surface does the two things the USN has
always avoided (and spent a great deal of money to avoid[1]);
increasing the length of the launch sequence and increasing the launch
signature. Thus coming to or close to the surface is a liability.

[1] For example, modifying the valves used to pressurize the launch
tubes in order to reduce the noise they generated. The pressurization
and flow control valves in the hovering system were also modified for
greater quietness because setting up that system as we made other
launch preps was a noisy and very obvious signature.

Across the history of the SSBN force reducing the indiscretion rate
and reducing the length and signature of the launch process have been
right behind accuracy (and not far behind at that) in the goals and
requirements of the system. Thus LORAN capability was added to the
bouy and wire (discussed below) and the BQS-3 secure fathometer
developed to avoid surface exposure. We did/do have mast mounted
antenna for Transit/GPS, but these are used as little as possible to
avoid going near the surface.

This is particularly true if you are going to be using satcomms for any
purpose - verification, mission update, etc.


We don't, not really. Satcomm is a backup for two other systems, one
which allows us to patrol deep (the bouy) and another which allows us
to patrol near (but not breaking as satcomm requires) the surface (the
wire). Also, SSIXS is a store-and-forward system (which requires
interrogation by the SSBN) rather than the continuous comms provided
by the systems the surface fleet and the rest of the DoD uses.

Secondly, the USN wanted to be able to use SSBN launched missiles
in counterfire, not a a countervalue, role. You can nuke a city without too
much accuracy, but if you want to plink hardened silos and buried targets
accuracy becomes much more important.


Certainly accuracy is important, but SSBN/SLBM system design also has
to consider issues (outlined above) that an ICBM system does not.
That was a prime driver behind the development of the ESGM/ESGN. Not
only was it more accurate than SINS, but it also required fewer and
less frequent (possibly detectable) external updates to maintain
overall system accuracy.

D.
--
Touch-twice life. Eat. Drink. Laugh.
  #65  
Old June 18th 04, 09:51 PM
Peter Stickney
external usenet poster
 
Posts: n/a
Default GPS Megadeath

In article ,
(Derek Lyons) writes:
(Stuf4) wrote:
You could likewise argue that Air Force strategic bombers had no need
for GPS because they had INS supplemented with TACAN and RADAR.


The behavior of the USAF across it's history supports that argument,
they were a latecomer to GPS, not an early adopter. The bombers
depended on radar and visual sightings once they entered the bombing
run. One suspects their involvement was more attributeable to
politics (increasing the accuracy of manned bombers increases their
viability, and being involved in a program that was in space but not
USAF controlled) as any desire for accuracy.


The big military beneficiary of GPS was the Army. The biggest problem
all commanders have had throughout history hasn't been finding the
enemy, but ficuring out where you own troops are. Maps get misread,
phase lines misreported, terrain features mis-identified, etc.
Nowadays, it's possible for a GPS-equyipped army to have a single,
undisuptable source for position information that isn't as susceptible
to being flummoxed by teh ministrations of a 2nd Lt.

The AIr Force's biggest problems, wrt GPS vs. on-board targeting
systems, is that it's only useful for weapons direction if you
actually know where the target is. Even today, most of the world's
maps aren't usable. (Show me the Syrian/Iraqi border for example -
it's never been properly surveyed, and you can't tell where it is, on
the ground.) This doesn't even include stuff like teh deliberate
disinformation that the Soviets engaged in, misstating the position of
geographic features and significant facilities by a wide margin.
(Yes, we're using GPS-aided weapons now. (Although INS is actually
the primary, and the GPS system provides updates) But in those cases,
either the target is spotted adn located by a nobserver who now,
through GPS, knows their own position, and can thus provide a good
location independant of the cartography, or teh target is spotted by
systems on board the aircraft - the same sort of deal, now that the
airplane can tell where it is.)


--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster
  #66  
Old June 19th 04, 12:20 AM
Scott M. Kozel
external usenet poster
 
Posts: n/a
Default National Space Policy: NSDD-42 (issued on July 4th, 1982)

Sander Vesik wrote:

Scott M. Kozel wrote:

GPS is not "offensive space-based weaponry", and for you to assert that
it is, shows you have an agenda to post disinformation about the topic.


Fine. And I doubt many people would argue against that. But surely you
don't want to claim that specificly military tailored and military
controlled navigation satellites used in weapons targeting are part
not of space militarisation?


I just got done refuting that notion. GPS has many civil uses, and is
no more "space militarisation" than is things like computers,
calculators, and microelectronics that makes modern satellites feasible,
plus weather satellites and other communication satellites.

Accurate ICBMs and SLBMs existed by the thousands, on both sides of the
Iron Curtain, decades before GPS ever existed.
  #67  
Old June 19th 04, 02:13 AM
Sander Vesik
external usenet poster
 
Posts: n/a
Default National Space Policy: NSDD-42 (issued on July 4th, 1982)

In sci.space.policy Scott M. Kozel wrote:
Sander Vesik wrote:

Scott M. Kozel wrote:

GPS is not "offensive space-based weaponry", and for you to assert that
it is, shows you have an agenda to post disinformation about the topic.


Fine. And I doubt many people would argue against that. But surely you
don't want to claim that specificly military tailored and military
controlled navigation satellites used in weapons targeting are part
not of space militarisation?


I just got done refuting that notion. GPS has many civil uses, and is
no more "space militarisation" than is things like computers,
calculators, and microelectronics that makes modern satellites feasible,
plus weather satellites and other communication satellites.


This is simply nonsense. When was the last time you saw a receiver on
sale that could actually make use of all GPS? GPS is not in any way
comparable to computers or modern electronics. It is not even designed
for civilian use, you may as well claim military cargo planes are not
military aircraft at all.

In fact, if you go by US laws, any placement of satellites in orbit at
all is space militarisation due to classification of satellites and
satellite technology as munitions


Accurate ICBMs and SLBMs existed by the thousands, on both sides of the
Iron Curtain, decades before GPS ever existed.


Which is utterly irrelevant to whetever GPS is space militarisation
or not.

--
Sander

+++ Out of cheese error +++
  #68  
Old June 19th 04, 02:36 AM
gcash
external usenet poster
 
Posts: n/a
Default GPS Megadeath

(Peter Stickney) writes:

The AIr Force's biggest problems, wrt GPS vs. on-board targeting
systems, is that it's only useful for weapons direction if you
actually know where the target is. Even today, most of the world's
maps aren't usable. (Show me the Syrian/Iraqi border for example -
it's never been properly surveyed, and you can't tell where it is, on
the ground.) This doesn't even include stuff like teh deliberate
disinformation that the Soviets engaged in, misstating the position of
geographic features and significant facilities by a wide margin.
(Yes, we're using GPS-aided weapons now. (Although INS is actually
the primary, and the GPS system provides updates) But in those cases,
either the target is spotted adn located by a nobserver who now,
through GPS, knows their own position, and can thus provide a good
location independant of the cartography, or teh target is spotted by
systems on board the aircraft - the same sort of deal, now that the
airplane can tell where it is.)


And to bring this back to space, I believe the last Shuttle hi-res mapping
mission had this as one of it's objectives. It's really really hard to get the
full resolution data from the government.

I remember an article about one of the research projects that benefitted was
trying to map/model the Amazon. They finally had terrain data that predicted
the Amazon would flow to the sea. Their former elevation data was too
inaccurate.

Does anyone remember TERCOM guidance for cruise missiles? The acronym stood
for TERrain COMparision and tried to fit output from a mapping radar in the
missile to a digital map, to figure out where it was. It sucked, but it was
eventually brute-forced to work. This was because we didn't have any decent
maps of the USSR. I'm sure they chucked that sucker as soon as GPS receivers
dropped below 50 lbs.

-gc

--
I've noticed lately that the paranoid fear of computers becoming intelligent
and taking over the world has almost entirely disappeared from the common
culture. Near as I can tell, this coincides with the release of MS-DOS.
-- Larry DeLuca
  #69  
Old June 19th 04, 02:53 AM
Scott M. Kozel
external usenet poster
 
Posts: n/a
Default National Space Policy: NSDD-42 (issued on July 4th, 1982)

Sander Vesik wrote:

Scott M. Kozel wrote:
Sander Vesik wrote:
Scott M. Kozel wrote:

GPS is not "offensive space-based weaponry", and for you to assert that
it is, shows you have an agenda to post disinformation about the topic.

Fine. And I doubt many people would argue against that. But surely you
don't want to claim that specificly military tailored and military
controlled navigation satellites used in weapons targeting are part
not of space militarisation?


I just got done refuting that notion. GPS has many civil uses, and is
no more "space militarisation" than is things like computers,
calculators, and microelectronics that makes modern satellites feasible,
plus weather satellites and other communication satellites.


This is simply nonsense. When was the last time you saw a receiver on
sale that could actually make use of all GPS? GPS is not in any way
comparable to computers or modern electronics. It is not even designed
for civilian use, you may as well claim military cargo planes are not
military aircraft at all.


You're the one who is posting nonsense. Obviously you've never seen the
commercially available receivers that instantly provide the exact
coordinates of a location to within a few feet. That has valuable civil
navigational uses.

In fact, if you go by US laws, any placement of satellites in orbit at
all is space militarisation due to classification of satellites and
satellite technology as munitions


Complete, utter nonsense.

Accurate ICBMs and SLBMs existed by the thousands, on both sides of the
Iron Curtain, decades before GPS ever existed.


Which is utterly irrelevant to whetever GPS is space militarisation
or not.


It is totally relevant, since those ICBMs and SLBMs can be (and were)
very accurate without GPS.

You're just looking for any far-fetched excuse possible to attack the
U.S.
  #70  
Old June 19th 04, 03:57 AM
Stuf4
external usenet poster
 
Posts: n/a
Default GPS Megadeath

From Derek Lyons:
(Stuf4) wrote:
You could likewise argue that Air Force strategic bombers had no need
for GPS because they had INS supplemented with TACAN and RADAR.


The behavior of the USAF across it's history supports that argument,
they were a latecomer to GPS, not an early adopter. The bombers
depended on radar and visual sightings once they entered the bombing
run. One suspects their involvement was more attributeable to
politics (increasing the accuracy of manned bombers increases their
viability, and being involved in a program that was in space but not
USAF controlled) as any desire for accuracy.


Perhaps I was not clear enough the first time. Derek, GPS was funded
because:

INS was neither accurate nor reliable.


INS may be accurate after being fixed to a known location, but INS
*does not measure position*. It does not even measure velocity. It
measures acceleration. And that means that the slightest error gets
integrated into a larger error in velocity, which gets integrated into
an EVEN LARGER error in position. Over short periods of time, INS
accelerometers were well known for running the position away with a
skewed platform.

Bomber missions take several hours and there are long stretches of
time between fixes where INS's often behave badly. It took diligence
of a highly skilled navigator to keep the INS "corralled", so to
speak, by regularly pumping good fixes into the system.

....and *even then* it was known to go inaccurate. Aside from errors
within the INS itself, even highly skilled navigators would make
errors in identifying radar targets to fix off of (there were lots of
other sources of error as well).


The optimal solution was to measure position directly, instead of
integrating all those errors.

The Air Force was in on the *ground floor* for the DNSS (renamed GPS),
so I don't know why anyone would say that they were latecomers. The
Navy had a 2-D system that worked at extremely low velocity. Jets
can't stop like subs can. And jets need 3-D position. It *was* the
Air Force who created such a system.

The most significant GPS contribution from the Navy was the atomic
clocks. The basics of the signal theory came from the Air Force. As
derived from MOSAIC, it was the technology that was designed for
positioning ICBM launches that gave us the system we use today. Air
Force technology.


Notice that even today the space shuttle is involved with a GPS
upgrade. For every flight to date it had multiple INS with multiple
TACAN. If this was deemed reliable and accurate enough then the GPS
conversion would be a complete waste of time and money.

Now talk to the astronauts and see how badly the want GPS.


They want it because it's available. There was certainly no such
clamor during the design phase.


While the shuttle is capable of doing automatic navigation fixes from
TACAN stations, it still suffers the accuracy problems inherent in INS
systems that don't get precise position updates.

Part of astronaut pilot training is practicing landings with *bad
nav*.


This is why they want GPS. They don't like the idea of their nav
system taking them down to a spot that is so far off the runway that
they crash. The primary issue isn't convenience. It isn't technology
fashion trends.

It's a matter of living, versus not.


The reason why there was no "clamor during the design phase" was
because there was no GPS when shuttle was designed. It was just a
theory.


~ CT
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Lunar base and space manufacturing books for sale Martin Bayer Space Shuttle 0 May 1st 04 04:57 PM
Unofficial Space Shuttle Launch Guide Steven S. Pietrobon Space Shuttle 0 April 2nd 04 12:01 AM
Clueless pundits (was High-flight rate Medium vs. New Heavy lift launchers) Rand Simberg Space Science Misc 18 February 14th 04 04:28 AM
Unofficial Space Shuttle Launch Guide Steven S. Pietrobon Space Shuttle 0 February 2nd 04 04:33 AM
Unofficial Space Shuttle Launch Guide Steven S. Pietrobon Space Shuttle 0 September 12th 03 01:37 AM


All times are GMT +1. The time now is 06:32 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.