Milsats Hiding as Space Debris

Pat Flannery wrote:

Now cut that out....It's not fair when some form of Cybernetic Master
Machine takes us mere mortals on.

Tell me more.

You may think this all impressive now...but just wait to some red-haired
super avenger rises from beneath the Ross Ice Shelf and uses his super
judo powers to sever your steel neck.

Is it because of Cybernetic Master Machine that he uses his super judo
powers to sever my steel neck?

Besides, he's going to be able to nail the comic version of Ann-Margret,
WHICH IS MORE THAN YOU OR ANY OTHER POL-ROB IS GOING TO BE ABLE TO EVER
DO, YOU SOULLESS STEEL SWINE!

Tell me more about soulless steel swine.

DOES THIS RING A BELL?: "Daisy, Daisy, give me your answer true..."
I THOUGHT IT WOULD, YOU MECHANICAL FILTH! ;-)

Is it because of your mother that you thought it would?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

We have been launching micro satellites in to multiple orbits from the
same vehicle for several years now, as many of these mini-sats are the
size of much of the orbiting debris. An example of the development of
such satellites is the 3 corner sat program and the recent launch this
past week st5 satellites.

In article , Gene Cash wrote:
Don't the GPS Block IIR satellites talk to each other? I do know the old
ones had to pass directly over the single ground station to be
controlled... [with IIR] this is no longer true and system-wide
changes can happen in a matter of minutes. That implies that the
individual satellites can relay information to each other. Does anybody
know how they do it?

They were described as having a "cross-link ranging system", but the piece
I saw suggested that this was mostly a way to improve the satellites'
knowledge of their own positions, thereby improving user position-finding
accuracy too. However, that discussion wasn't very detailed. If they're
doing radio transmission to each other for ranging, it would make sense to
put a command-and-control data path in there too. It wouldn't have to be
very fast to be useful.

It wasn't clear whether this was a separate radio system, or just
receivers so they could hear each other's broadcast signals. Might have
to be a separate system, given that all the broadcast signals are on the
same frequency (you pick out one from the others by looking for its
particular pseudorandom modulation code, not by changing frequency) and so
leakage from the satellite's transmitter might well overpower a receiver
for the GPS signals themselves.

If it is separate, it might use one of the atmospheric-absorption bands.
The advantage is that it's hard to eavesdrop on (or jam) from the ground.
The disadvantage is that the frequencies are high enough that working with
them is reportedly a bit painful. I'm not sure whether a designer working
15 years ago would have chosen them or not.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

"Rusty" wrote in message
oups.com...

Pat Flannery wrote:
Rusty wrote:

http://www.au.af.mil/au/awc/awcgate/cst/occppr02.htm


Now cut that out....It's not fair when some form of Cybernetic Master
Machine takes us mere mortals on.
You may think this all impressive now...but just wait to some red-haired
super avenger rises from beneath the Ross Ice Shelf and uses his super
judo powers to sever your steel neck.
Besides, he's going to be able to nail the comic version of Ann-Margret,
WHICH IS MORE THAN YOU OR ANY OTHER POL-ROB IS GOING TO BE ABLE TO EVER
DO, YOU SOULLESS STEEL SWINE!
DOES THIS RING A BELL?: "Daisy, Daisy, give me your answer true..."
I THOUGHT IT WOULD, YOU MECHANICAL FILTH! ;-)

Manion Butler


I am Bbo of Borg prepare to be amissilated!

;-)


Rusty


I am Pixar of Borg. You will be animated.

:-D

J

Communications between satellites is just one of the many possible uses
for space based lasers, and given the fact we are 9 years down the line
from the report cited below it is quite plausible some of these
technologies are currently in use.

LASERS IN SPACE TECHNOLOGICAL OPTIONS FOR ENHANCING US MILITARY
CAPABILITIES
by Mark E. Rogers, Lieutenant Colonel, USAF
November 1997 Occasional Paper No. 2 Center for Strategy and Technology
Air War College Maxwell Air Force Base, Alabama
Page 49-51
"Laser Communications and Data Relay ...Laser communications offer a
number of advantages over radio-frequency and microwave systems. First,
the potential data rate is much higher because of the carrier frequency
is much higher. The NWV study states that the data rate could exceed 10
billion bits per second (Gbps).89 Second, the link can be more secure
given the narrow laser beam. The implication is that someone would need
to get inside the beam to intercept the message, interrupt the beam to
the intended receiver, and thus signal that an intrusion had occurred.
This fact also makes it very hard to jam laser communication links.
Third, if the carrier wavelength operates outside the visible region,
the communication would invisible, and thus covert, unless
electro-optical systems are used to search for the beam. These last two
advantages are captured in the notion of a Low Probability of
Intercept/Low Probability of Detection (LPI/LPD) communication system.
Fourth, because of the linearity of the atmosphere for low peak-power
laser beams, there is no -cross-talk" between laser beams, reducing
this source of signal degradation. Fifth, the laser communication
system will be much smaller and lighter than comparable radio-based
systems because the output -antenna" is much smaller, the laser is
much smaller than microwave generators, and the power consumption is
lower. These factors produce substantial savings in payload launch
costs."

In article , Gene Cash wrote:
Don't the GPS Block IIR satellites talk to each other? ...
They were described as having a "cross-link ranging system"...
If it is separate, it might use one of the atmospheric-absorption bands.
The advantage is that it's hard to eavesdrop on (or jam) from the ground.
The disadvantage is that the frequencies are high enough that working with
them is reportedly a bit painful. I'm not sure whether a designer working
15 years ago would have chosen them or not.

Hm. Well, I assume you're referring to the original satellites, but the
Block IIR is a lot newer, with the first one delivered to the USAF by
Lockheed-Martin in Feb '05.

Uh, no, the first Block IIR was lost in the Delta II launch failure in
January 1997. That's why I said "15 years ago" -- even with a reasonably
brisk schedule, design would have had to start a few years ahead of launch.

This is according to
http://www.lockheedmartin.com/wms/findPage.do?dsp=fec&ci=16360&rsbci=11474&fti=134&t i=0&sc=400

Read it more carefully :-) -- it notes that there are twelve IIRs already
operational. What LockMart has just delivered is the first IIR-M, the
"modernized" version of the IIR with several additional improvements.
(Naturally they couldn't call it IIS and save a lot of confusion...)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

In article .com,
wrote:
Communications between satellites is just one of the many possible uses
for space based lasers, and given the fact we are 9 years down the line
from the report cited below it is quite plausible some of these
technologies are currently in use.

Uh, why do you think this Air War College paper has special significance?
The idea of laser communications in space has been around a *lot* longer
than nine years.

For example, if you look through "Laser Satellite Communications", Katzman
ed., Prentice-Hall, 1987, you'll find photos of USAF lasercom experiments
done in the late 1970s, with an eye on space applications. If you look at
the "Photonics for Space Environments II" proceedings (SPIE 1994), you'll
find a survey paper on why laser communications systems hadn't yet made it
into space, discussing a number of practical problems.

Laser communication has long been recognized as having a lot of potential,
but turning that potential into reality has been harder than many people
expected. Avalanche photodiodes revolutionized receiver design about 15
years ago, but we're still waiting for the equivalent for transmitters --
preferably something with the reasonably convenient characteristics of
diode lasers, but higher power output.

(Individual diode lasers hit fundamental limits when you try to scale them
up, and phase-locking several of them together so they function as a
single laser is hard.) (You can buy laser-diode clusters and bars, but
they're not phase-locked so their output is incoherent. They're great
infrared light sources, but they're not usable as lasers.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Henry Spencer wrote:
There was a development project to put laser crosslinks on the DSP birds,
so continental-US ground stations could talk to all of them and they
wouldn't need overseas ground stations.

For the past five years or so ESA has been running a laser comms link
between SPOT-4, Artemis and a ground station in Tenerife. The project
is called SILEX; SPOT-4 is at about 900 km and Artemis is in GEO.
in Tenerife.

JAXA has now also networked one of their LEO sats into Artemis.

--
Andrew B

wrote:

Third, if the carrier wavelength operates outside the visible region,
the communication would invisible, and thus covert, unless
electro-optical systems are used to search for the beam.


Actually, in the vacuum of space the beam would be hard to see even if
it were in the visible part of the spectrum.

Pat

In article ,
Andrew Bunting wrote:
For the past five years or so ESA has been running a laser comms link
between SPOT-4, Artemis and a ground station in Tenerife.

Yes, after many years of proposals and development, this is -- apart from
perhaps some classified things -- the first actual in-space laser link.
Even this is nominally an experiment rather than an operational system.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |