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'[OT:] Whoops'
2004\10\17@190418 by Dave VanHorn

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Chinese satellite crashes into building

BEIJING - Part of a Chinese satellite that was returning from orbit crashed
into an apartment building, wrecking the top floor but causing no injuries,
media reports said yesterday.


http://straitstimes.asia1.com.sg/eyeoneastasia/story/0,4395,278696,00.html

The Youth Daily, quoting Chinese space experts, said: 'The landing
technology of our country's satellites is very mature and the precision of
the landing point is among the best in the world.' -- AFP, AP


So it's the government version of "I meant to do that!" ?

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2004\10\17@192119 by Jinx

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> So it's the government version of "I meant to do that!" ?

So it was a friendly "we know where you live" message
to a dissident ?

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2004\10\17@192803 by Dave VanHorn

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At 06:19 PM 10/17/2004, Jinx wrote:

> > So it's the government version of "I meant to do that!" ?
>
>So it was a friendly "we know where you live" message
>to a dissident ?

Maybe they just meant that they were in the top 10 list of accuracy of
return point, by country.

:)
 

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2004\10\17@194628 by hilip Stortz

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yeah, and it would almost have to be a surveillance satellite in the
first place, returning the whole thing just as we recover film packs
being parachuted back to earth (i'm sure we're still doing that with
some of our spy satellites).  if a spy satellite fails the public
doesn't usually know, unless the whole thing is supposed to come back
and the landing part of it is what broke.

Dave VanHorn wrote:
--------
> So it's the government version of "I meant to do that!" ?
------

--
President George W. Bush, Vice President Richard B. Cheney, Secretary of
Defense Donald H. Rumsfeld,
and Attorney General John D. Ashcroft have committed violations and
subversions of the Constitution
of the United States of America.  <http://www.VoteToImpeach.org>  They should
be charged with high treason
and as leaders deserve the highest penalty.  If there is no rule of law
there can be no civilization.
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2004\10\17@195631 by Dave VanHorn

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At 06:48 PM 10/17/2004, Philip Stortz wrote:

>yeah, and it would almost have to be a surveillance satellite in the
>first place, returning the whole thing just as we recover film packs
>being parachuted back to earth (i'm sure we're still doing that with
>some of our spy satellites).

I don't think so, but they don't always tell me these things.
My father worked on some of those systems back in the late 60's and early 70's.

The film capacity would be a pretty severe limitation.
AFAIK, there isn't anything that they can't do without film these days.

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2004\10\17@210603 by Jinx

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> Maybe they just meant that they were in the top 10 list of accuracy of
> return point, by country.
>
> :)

Ha. Still, better than "a part of a Chinese _astronaut_ crashed into...."

(actually, the reporting give me the initial impression that the satellite
had
broken up, when in fact the bit that crashed is the part that's supposed
to be recovered - which it was, kind of)

'The landing technology of our country's satellites is very mature and
the precision of the landing point is among the best in the world.'

That is just such wishy-washy PR. The obvious question that anyone
who read that would ask is if it's very mature and precise, it shouldn't
have crashed. It did, so why ? It just seems so hard for any admin to
just 'fess up and say there was an error somewhere. All they've done
now is get an extra splatter of egg (foo yong) on their faces.  Guys guys
guys, at least in public try blaming the equipment first

Could be they were using counterfeit gear, although goodness what
country indulges in that sort of practice.........


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2004\10\20@134446 by hilip Stortz

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it definitely was done that way on some satellites at one time.  i
suspect it's still being done for high resolution work, video is still
much lower resolution.  some of these satellites film the entire planet
every day or so, and then eject a film container on a parachute etc.
which is then developed and studied both manually and by computer
imaging looking for any change.  of course for more real time
surveillance video type techniques are used, but they are limited in the
area and resolution trade offs available, i.e. with film you can image
the whole planet with high resolution film and optics and enlarge it
later, concentrating on the areas that are interesting or that show a
significant change over time.  i'm sure many of the satellites still use
film for these reasons, while others don't, and there may be some that
have both capabilities.  spy satellites are pretty sophisticated and a
great deal is spent on them, some can even change their orbit on
command, requiring a significant fuel reserve.  the limits shrink
rapidly when nearly infinite money is available, as it often is for
these types of projects.

Dave VanHorn wrote:
{Quote hidden}

-------

--
President George W. Bush, Vice President Richard B. Cheney, Secretary of
Defense Donald H. Rumsfeld,
and Attorney General John D. Ashcroft have committed violations and
subversions of the Constitution
of the United States of America.  <http://www.VoteToImpeach.org>  They should
be charged with high treason
and as leaders deserve the highest penalty.  If there is no rule of law
there can be no civilization.


____________________________________________

2004\10\20@153838 by Howard Winter

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Philip,

On Wed, 20 Oct 2004 10:27:05 -0600, Philip Stortz wrote:

> it definitely was done that way on some satellites at one time.

Yes, I believe "Corona" was the project name for the first set of these.  If I remember rightly the film "Ice
Station Zebra" was based around recovering a film canister that went astray.

I think they were usually recovered in the air by an aircraft with a big "V" shaped catching arm on the front,
snaring the parachute cord.  Can you imagine the face of the first pilot being told what he had to do?  :-)

Cheers,


Howard Winter
St.Albans, England


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2004\10\20@164821 by Russell McMahon

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> I think they were usually recovered in the air by an aircraft with a big
> "V" shaped catching arm on the front,
> snaring the parachute cord.  Can you imagine the face of the first pilot
> being told what he had to do?  :-)

Yes - a look of utter glee !!!!


       RM

____________________________________________

2004\10\20@200942 by Jake Anderson

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i'd go so far as to say i'm 90% sure that there are no film based satellites
in orbit.
SPOT has ~1m ground resolution as i recall the most detailed of the
commercial satellite fleet and it is digital, it can cover the same point on
the earth every 3 days though at different angles.

if the CCD sensor has more resolution than the optics then it isnt hard to
do. I havent heard of anybody shooting video from space, though it would
probbly be possible you would need to be in very low orbit with a mirror
around the size of hubble to make it actually worthwhile.

using film would be horribly inefficent, rather than spending 500 million
dollars 3 or 4 times a year to launch a new satellite because your old one
ran out of film, spend 500 million dollars on a CCD, it will be far more
sensitive than film (QE of ~1 vs 0.2) and far higher resolution.
put a BigAss (TM) ground station somewhere you controll, and download the
data every day or so.
with a few ground stations you could download every 90 minutes or so. rather
than film where if something goes wrong you have to go chasing this film
canister somewhere in the arctic while the people you are spying on are
doing the same.


> {Original Message removed}

2004\10\22@215323 by hilip Stortz

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you show me a ccd with more pixels than a 2" wide piece of high
resolution film and i might believe you!  the point is to photograph
whole countries, with far better resolution than one meter, more like
several centimeters or better.  it is possible in the i.r. and in the
visible when weather allows.  film is cheap.  the cost of launching a
satellite with something other than the shuttle isn't that high, and it
doesn't take that much film.  even the old ones had enough film to work
for years.  i've seen footage of the navy recovering film at sea (a long
time ago, but i'm sure it's still done, film has much, much higher
resolution than any ccd array any one has ever made).  besides, the
bottleneck hasn't been in data collection for a long time, it's in
processing that information.  with film you scan it at your'
convenience, it's already archived and you can search around on it
forever.  apparently computers have been used for a long time to detect
"changes", and then those areas are manually viewed by experts.  using
film would be very, very efficient.  how much secure bandwidth do you
need to cover europe even at 1M resolution in the i.r. and visible at
12+bits?  a lot, and encryption is expensive as well, particularly for
long data streams with some known properties (sending essentially the
same data, i.e. the parts that haven't changed much, over and over makes
it very, very hard to produce a secure encryption).  

film, still used for movies for a reason (yeah, some people have played
with digital solutions, they aren't ready, they aren't ready for space
even with the nsa having it's own wafer fab).  again, i've seen it, and
the footage was convincing and it's logical.  these satellites are
tremendously sophisticated.  we even have some that can temporarily go
into very low orbit and "hear" things, probably only jets being tested
or bomb test etc., but we do have the capability, we had it a long, long
time ago.  in the 70's there were reports we could read newspaper
headlines, that's not unreasonable under good conditions with great
optics.  adaptive or flexible optics have been around for a long time,
they can adapt to things like thermal distortion from the atmosphere.
the main job of the film satellites is to find new missile and other
military bases and follow troop movements.  you need good resolution to
determine exactly what you are looking at, particularly with the well
known use of decoys.  you need to see just how a building was built and
what went into it, you need to see just who is marching.  in vietnam we
had seismic troop monitoring sensors to detect troop movement, they were
disguised as rocks and drop out of planes by the 10's or 100's of
thousands and reported daily to a satellite!  

these people have unlimited money for all intensive purposes.  the
satellites with ccd and similar sensors are for real time observation of
particularly interesting events and can easily be re-tasked, i.e. they
can change their orbital height and direction on command to reach
specific areas at specific times or to frequently pass over key areas.
those same areas are also photographed on high resolution film to
provide the details.  it can be dropped to earth at any time and
processed in under an hour, ready for intelligence people on the ship to
start critical analysis of those same key areas with enough resolution
to see exactly what is going on, to count people and know if they are
men or women, if they are in uniform, what types of construction gear
they are using, how thick walls are and what they are made out of etc.
hell, we've used gamma ray spectroscopy to map some of the minerals on
the moon and other planets!  that requires a high energy gamma beam and
a gamma spectrometer, you basically make some of the material you are
"analyzing" radioactive and then look at the gamma it emits during decay
(many isotopes decay rapidly enough to observe, and they produce
specific wavelengths or energy levels of gamma radiation) and use the
spectroscopic data to determine what elements are present on or near the surface.

it's about resolution, high, high resolution over very large areas.  how
wide a stripe can the largest ccd array take?  how many pixels?  how
wide is that at 1/4M (conservative, i'm sure the film is much higher)?
how many passes would it take to image 1000km square?  with film you can
do huge areas in very few passes, and you get large sections at the same
time which you need for analysis, you want to be able to see a whole
complex at the same instant in time, not pieces of it hours or minutes
apart.  you can't count planes, trucks, and bombs on a base without
seeing the whole thing at the same time, and that's one of the things we
like to be able to do.  to see trucks come and go and count them etc.
i'm 100% sure film is still widely used in addition to other techniques.
each has it's own advantages and weaknesses, it's own niche in
intelligence gathering.  it's not about the efficient use of money, it's
about efficiently collecting as much data as possible.  you need great
optics for film or ccd, but film has always had much better resolution
and sensitivity.  to the small extent that money does matter, it's a lot
cheaper to put film behind those optics than a ccd, and more reliable.
even collecting film cans at sea is more reliable than downloading
through a dish, that can be jammed, it's very hard for another power to
know when the film can will drop or which ship is picking it up today,
and if they did put aircraft in the way we could rearrange our schedule,
if it has to be downloaded it has to be stored, hard drives in space are
not at all easy, and you still have to find a dish to send it to,
regularly, and try to keep people from intercepting it and knowing
exactly what you know (bluffing is a huge part of the intelligence game).

like i said, resolution, resolution, resolution.  some film is really
amazing, electronic image sensors have a very long way to go to compete
with film.  and film stores the data as well as collecting it and it's
easy to make film work in space.

spot's resolution is limited by what the government was willing to allow
them to do, it's not an indication of what can be done with really good
optics.  in fact it's proof that real spy satellites can do much, much
better.  and spot can't cover much area in a day or a wide stripe in
each pass at that resolution.  it can do wide stripes at lower
resolution or it can do small areas at that artificially low resolution
and the image sensor is the limit on that.  even with the spot optics
film could do a wider track at 1M resolution, but spot has a different
mission, and for a private enterprise huge naval operations in
international water are a bit expensive, and unnecessary for spot's
mission.  you can also cram a truly huge amount of film in a small
space, so getting enough aboard to last a long time isn't that big a
problem, and that problem is also reduced by using very high resolution film.

Jake Anderson wrote:
{Quote hidden}

> > {Original Message removed}

2004\10\23@020043 by Adrian Round

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source=Film based satellites were phased out in the late 70’s.   While quite advanced for their time, they suffered from a number of problems.  You had no idea of what imagery you had captured prior to recovering the canister.  Was your mission targeting valid (not always), was the target obscured by cloud (frequently), did the film transport mechanism fail (sometimes), do I de-orbit the canister early and waste the remaining film, are the images from the start of the mission still relevant when you de-orbit the canister (hopefully)?

In the 80’s, C4I systems evolved to allow commanders to use what had previously been viewed as “strategic” intelligence at the tactical level.  The film-canister return systems could not keep pace with this new requirement for near real time space based intelligence.   Digital imaging and near real-time distribution of the data resolved this issue.  Now you had almost instant images, rapid assessment of the mission success or the need for retargeting, and intelligence information in the hands of the commanders in time for it to be employed at the tactical level.  Best of all, just like digital cameras in the civilian world, you can take lots of pictures without worrying about wasting the film.  Not sure about something, take a picture.  If it turns out to be nothing, all that’s is wasted is photons on a solar array and some bandwidth.  Given that the resolution of the digital imaging systems surpassed that of the older film return systems, you could also do the “strategic” intelligence gathering as well.



---
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2004\10\24@062400 by Lee Jones

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The assertions in this message bothered me such that I had to
address the technical issues involved.

>> i'd go so far as to say i'm 90% sure that there are no film based
>> satellites in orbit.

> you show me a ccd with more pixels than a 2" wide piece of high
> resolution film and i might believe you!

Assuming 100 line pairs per millimeter, a reasonable value for high
resolution film, a 2" wide swath of film would need 5,080 pixels for
equivalent resolution.  To get 100 lpm, you need an excellent optics
system conpensated for the rapid satellite motion and decent seeing
conditions.  Large, expensive, but doable.  As to brightness, film
can retain 5 to 7 f-stops of dynamic range.

Look at Creo's Leaf Valeo 22 megapixel digital back (5,356x4056) with
12 f-stops of dynamic range; output is 16-bits per channel; removable
back for medium format cameras.  It is a battery operated stand-alone
unit (i.e. does not need to be tethered to a computer).

Or look at the Sinar 54H or 54S digital backs at 22 megapixels
(5,440x4,080); output is 14-bits per RGB color channel.

These are examples of commerical products that have been on the market
for a year or more.  There are other, similar competing products.  All
are robust and inexpensive enough (though certainly not cheap) to be
viable commercial products.

We can probably assume that the classified research & development
groups of a major world power, such as the United States National
Reconaisance Office, would have been able to create a device with
at least this much capability in small manufacturing volumes for
spy satellites for a number of years now.  Remember, price is not
a major concern.


> the point is to photograph whole countries, with far better
> resolution than one meter, more like several centimeters or better.
> it is possible in the i.r. and in the visible when weather allows.
> film is cheap.  the cost of launching a satellite with something
> other than the shuttle isn't that high, and it doesn't take that
> much film.

Let's posit that the US wanted to monitor the old Soviet Union.

Russia is 16,995,000 square kilometers.  The Soviet Union had far
larger land area.  But I'll stay with 17 x 10^6 square kilometers.
That's 17 x 10^12 square meters.  And let's assume that there is
no overlap between strips of film.  In reality, there would be some
overlap, but using no overlap sets an absolute minimum of film needed.

At 1 meter resolution, that means we need 17 x 10^12 pixels to cover
Russia.  At 5,080 pixels per 2" wide, we'd need a 2" wide strip of
film that's 1.32 x 10^6 inches or 110,000 feet or 33,500 meters long.
If the film is 0.005 inches thick (I just measured some 120 film),
then this is at least 8 cubic feet of film for one image of Russia.

To meet your "far better resolution than one meter" specification,
let's use roughly 3cm resolution.  That requires 1,000 times as much
film.  That's 8,000 cubic feet or 230 cubic meters of film.  And you
need more film to provide for overlap, more volume for film handling
mechanisms, more volume for light-tight film canisters that can
withstand reentry, lots more film for subsequent reimaging passes to
allow comparative analysis, etc.

That's just more volume than can fit into a spy satellite.

Going the other way, a nation wanting to monitor the US, gives
roughly comparable answers.  The US is roughly 1/2 the land area
of Russia.


> film, still used for movies for a reason (yeah, some people have
> played with digital solutions, they aren't ready

Movie production has moved to mixed film and digital or entirely
digital.  Post-production steps are almost entirely digital now.

Film is still used for movie distribution because digital methods of
projection are too expensive or technically infeasible.  LCD light
modulation equipment either doesn't have the resolution or can't
handle the high temperatures present near a sufficiently bright
light source or both to create theater size images.  Or, if they
can do it, the equipment can't do it long enough to be economical.


> we even have some [satellites] that can temporarily go into very low
> orbit and "hear" things, probably only jets being tested or bomb test
> etc., but we do have the capability, we had it a long, long time ago.

This is just not feasible.  Spy satellite orbit adjustments are already
limited by the amount of propellent that can be carried.  The energy
needed for the delta-V (change in orbital velocity) to radically
change orbital altitude weighs way too much.


> it's about resolution, high, high resolution over very large areas.
> how wide a stripe can the largest ccd array take?  how many pixels?
> how wide is that at 1/4M (conservative, i'm sure the film is much
> higher)? how many passes would it take to image 1000km square?  with
> film you can do huge areas in very few passes

Using 9" wide aerial film at 1 meter resolution, you'd image a strip
of ground that was just over 22 kilometers wide.  So it would take
45 passes to 65 passes (at 30% overlap) to cover a 1000km wide strip.

                                               Lee Jones

____________________________________________

2004\10\24@152950 by Peter L. Peres

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On Sun, 24 Oct 2004, Lee Jones wrote:

> The assertions in this message bothered me such that I had to
> address the technical issues involved.
>
>>> i'd go so far as to say i'm 90% sure that there are no film based
>>> satellites in orbit.
>
>> you show me a ccd with more pixels than a 2" wide piece of high
>> resolution film and i might believe you!

A linear ccd can exceed the number of pixels a film can have simply
because it can be made wider (several strips partly overlapping f.ex. to
guarantee perfect registraton at junctions). Your scanner probably already
does this. A $100 scanner will scan 4000+ pixels with only 600dpi.

The problems with ccds so far have been dynamic range and poor low light
operation. Both have been overcome afaik. Then there is the small problem
of umpteen billions of bytes to store and to download. That has been
solved too.

So I don't think they use film anymore, except for very special
applications.

Peter
____________________________________________

2004\10\25@080403 by Alan B. Pearce

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>So I don't think they use film anymore,
>except for very special applications.

In all this discussion about film in satellites, everyone seems to have
forgotten why they hired some stunt flyers to grab the Genesis spacecraft -
they no longer had the experience to catch these things, as they no longer
retrieve film canisters.

____________________________________________

2004\10\26@065952 by Peter L. Peres

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On Mon, 25 Oct 2004, Alan B. Pearce wrote:

>> So I don't think they use film anymore,
>> except for very special applications.
>
> In all this discussion about film in satellites, everyone seems to have
> forgotten why they hired some stunt flyers to grab the Genesis spacecraft -
> they no longer had the experience to catch these things, as they no longer
> retrieve film canisters.

It wasn't that, afaik something failed and the capsule came screaming down
(no parachute deployment). You don't catch something like that, you move
out of the way probably, and hope for the best. Also they were trying to
recover aerogel not film.

Peter
____________________________________________

2004\10\26@075142 by Alan B. Pearce

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>It wasn't that, afaik something failed and the
>capsule came screaming down (no parachute deployment).

Correct, but the guys in the helicopters who were out there to catch it if
the parachutes had deployed, were stunt pilots from the movie industry, who
had been hired for the purpose because NASA and the US military no longer
have people experienced in doing this catching, because they do not use film
anymore - my original point.

____________________________________________

2004\10\26@081628 by Russell McMahon

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>> ... Genesis spacecraft ...

> It wasn't that, afaik something failed and the capsule came screaming down
> (no parachute deployment).

The g sensors used to trigger the deployment system were connected backwards
(or, viewed another way) the sensors were installed upside down.




       RM


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