Orbital surveillance satellites now exceed 1 inch resolution.

The most recent public estimates of spy satellite resolution
capabilities give them as about 10 centimeters, 4 inches. However, it
is widely known that the most advanced astronomical space
observatories lag what is currently available for military and
intelligence satellites. The Hubble Space Telescope for example was
derived from early technology surveillance satellites.
Then since the James Webb Space Telescope has a segmented 6.5
diameter mirror, very likely this at least is available now for
surveillance satellites.
I discussed the capabilities for such a mirror for space-borne
imaging in the post below. At 300 km altitude it would have better
than 3 cm resolution, about an inch. Spy satellites frequently have
elliptical orbits that can bring their altitude to half this at
closest approach, so their max resolution will be perhaps half this,
1.5 cm to 1 cm.
The James Webb Space Telescope is however an infrared telescope. The
question I had was whether the mirror smoothness tolerances required
at visible wavelengths were available using the beryllium material
used in the segmented mirror of the James Webb. From this web site we
may conclude that this is indeed possible:

ESO Press Photos 34a-b/97
12 December 1997.
First M2-Unit and Beryllium Mirror Delivered to ESO.
http://www.eso.org/outreach/press-re...hot-34-97.html

The ESO's Very Large Telescope (VLT) uses 1.2 meter beryllium mirrors
for its secondaries. This requires visible wavelength smoothness since
the VLT will operate at both visible and infrared wavelengths. The
James Webb hexagonal mirror segments are each 1.3 meters in diameter.
So we may conclude beryllium mirrors of this size could be polished to
the smoothness required for visible light observations.

This question was raised by me in regards to astronomical planetary
imaging: how soon could this be adapted to space missions to the
planets? The James Webb telescope is a 4 billion dollar mission.
However, a large part of this cost probably has to do with the fact of
the high reliability required for this mission that has to operate far
away from the Earth and therefore can not be serviced by human
missions, and because of the fact the entire spacecraft's structure
has to be optimized to keep the cryogenic temperatures required for
the highly sensitive infrared observations.
Reductions in cost for similar sized planetary missions can be fueled
by commercial imaging interests. It is clear there there would be
commercial uses for Earth imaging at 1 inch resolution, though this
would raise clear privacy concerns. The technology for producing such
large foldable space mirrors has been patented so can now be licensed
by commercial imaging concerns:


Deployable space-based telescope.
Abstract
A large aperture light-weight space borne telescope is provided which
may be launched by a relatively small launch vehicle. A 6 to 8 meter
primary telescope composed of, e.g., 30 segments arranged in two
concentric rings is provided. Supplemental outer mirror segments are
stowed behind and substantially perpendicular to the main mirror which
is usable in the absence of supplemental mirror deployment. Deployment
of outer mirrors segments provides a large aperture telescope with a
large field of view. Other deployable components include a secondary
mirror, a bus, deployable with respect to the optics portion, and one
or more sun shade sheets or panels.
Patent number: 5898529
Filing date: Jun 20, 1997
Issue date: Apr 27, 1999
Inventors: Wallace W. Meyer, Robert A. Woodruff
Assignee: Ball Aerospace & Technologies, Inc.
http://www.google.com/patents?vid=USPAT5898529



Bob Clark



************************************************** *********************
Newsgroups: sci.astro, sci.physics, sci.geo.geology,
alt.sci.planetary, sci.astro.amateur
From: "Robert Clark"
Date: 10 Jan 2007 09:12:09 -0800
Local: Wed, Jan 10 2007 1:12 pm
Subject: We will soon be able to resolve Mars microbes from orbit. ;-)

On another space oriented forum I noted:

"It took 20 years to increase the resolution by a factor or 10 over
Viking with the Mars Global Surveyor mission. But only 10 years to
increase the resolution over that of MGS by a factor of 10 with Mars
Reconnassance Orbiter.
Could we increase the resolution over MRO by another factor of 10 to,
gulp, 3 cm per pixel in only 5 years this time?"

Funny though, that rather off-the-cuff estimate of mine is close to
what is possible.
To resolve 3 cm in the optical from say a 300 km orbit would require
a
6 meter mirror. The James Webb Space Telescope will have a 6.5 meter
mirror and is scheduled for launch in 2013. But it was originally
scheduled for launch in 2011:

James Webb Space Telescope.
http://en.wikipedia.org/wiki/James_Webb_Space_Telescope

So going by this rate, it'll be 3mm/pixel 2.5 years after that, and
300 microns 1.25 years after that, and ...
Hmm, in less than a decade then we should be able to resolve
microbes
from space.

Admittedly though, the JWST is a 4 billion dollar mission. Also it
uses a beryllium metal mirror for infrared astronomy only. The
beryllium makes the mirror lightweight but it is unclear if you can
achieve the much more stringent smoothness requirements at optical
wavelengths with a metal mirror.
As for the data storage and transmission of the large files for such
high resolution images, data storage capacity and costs are doubling
and halving each year, respectively:

Bye-bye hard drive, hello flash.
By Michael Kanellos
Staff Writer, CNET News.com
Published: January 4, 2006, 10:00 AM PST
"Currently, NAND chips double in memory density every year. The
cutting-edge 4-gigabit chips of 2005, for example, will soon be
dethroned by 8-gigabit chips. (Memory chips are measured in gigabits,
or Gb, but consumer electronics manufacturers talk about how many
gigabytes, or GB, are in their products. Eight gigabits make a
gigabyte, so one 8Gb chip is the equivalent of 1GB.)
"Another driving factor in the uptake of the technology is cost: NAND
drops in price about 35 to 45 percent a year, due in part--again--to
Moore's Law and in part to the fact that many companies are bringing
on
new factories."
http://news.com.com/Bye-bye+hard+dri...0-1006_3-60058...

MRO uses the type of flash memory chips discussed here.

Also, interestingly NASA had planned a laser communication orbiter
for
Mars for launch in 2010 before it was canceled:

Record Set for Space Laser Communication.
By Ker Than
Staff Writer
posted: 05 January 2006
02:11 pm ET
http://www.space.com/missionlaunches...aser_comm.html

Mars Telecommunications Orbiter: Interplanetary Broadband.
By Bill Christensen
posted: 05 May 2005
06:41 am ET
http://www.space.com/businesstechnol...novel_marstele...

This would have allowed data transmission rates of a hundred times
greater than what is currently available.

It was the great cost overruns overruns that led to cancelling of
the
Mars Telecommunications Orbiter, and great cost overruns also
threatened JWST as well.
That the costs for computer technology are dropping exponentially
with
capacity increasing exponentially is no doubt fueled by the free
market
in this sphere.
Conversely, that launch costs are staying static is no doubt because
the launches are controlled by large governments. When private
companies become the primary financer and purveyor of launches, the
launch costs will also drop dramatically.


Bob Clark

************************************************** *********************

On Apr 23, 5:49 am, Robert Clark wrote:
I discussed the capabilities for such a mirror for space-borne
imaging in the post below. At 300 km altitude it would have better
than 3 cm resolution, about an inch. Spy satellites frequently have
elliptical orbits that can bring their altitude to half this at
closest approach, so their max resolution will be perhaps half this,
1.5 cm to 1 cm.

Nah. Looking at this morning's imagery of your house, I can't
even make out for sure how many eggs you had. So don't be too
paranoid.

Cute dog you have. Some interesting titles in your library too.

- Randy

Surely the correct title for this post would be:

"It may be possible for future orbital surveillance satellites to exceed 1
inch resolution", as this appears to be the claim you are actually making.

In article ,
"Peter Webb" wrote:

Surely the correct title for this post would be:

"It may be possible for future orbital surveillance satellites to exceed 1
inch resolution", as this appears to be the claim you are actually making.

It would take one HELL of a focal length!

On Tue, 24 Apr 2007 03:36:18 GMT, Orval Fairbairn
wrote:

It would take one HELL of a focal length!

About 55 meters. But for a 6.5 meter aperture, that's just f/8.4, which
is pretty much the sweet spot for RC and Cassegrain designs.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

The advantage seems to be not in narrower and narrower area scans,
but in higher orbits that allow long dwell times over targets of interest --
eventually, you'd want an optical instrument in GEO that had tenth-meter
resolution -- or in Sun-Earth L1 so you have a continuously sunlit surface
to observe.

On Fri, 27 Apr 2007 11:29:57 -0500, "Jim Oberg"
wrote:

The advantage seems to be not in narrower and narrower area scans,
but in higher orbits that allow long dwell times over targets of interest --
eventually, you'd want an optical instrument in GEO that had tenth-meter
resolution -- or in Sun-Earth L1 so you have a continuously sunlit surface
to observe.

Good point. A theoretical ground resolution of one inch is all very
well, but doesn't do you much good if you can't aim your camera to that
precision. When Hubble imaged the Moon, it had to execute some tricky
attitude changes to reduce motion blur, and was only partly successful.
Various deep space probes have done the same when making close flybys of
moons.

One advantage of a large objective, besides resolution, is that you
collect a lot of photons and can make a shorter exposure. I'm sure this
is critical to getting high resolution ground images of the Earth, where
the atmosphere limits resolution (less of a problem looking down than
looking up, but still something that has to be dealt with).

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

"Jim Oberg" wrote:
The advantage seems to be not in narrower and narrower area scans,
but in higher orbits that allow long dwell times over targets of interest --
eventually, you'd want an optical instrument in GEO that had tenth-meter
resolution -- or in Sun-Earth L1 so you have a continuously sunlit surface
to observe.

Actually, Sun-Earth L1 isn't that good a position. You want some
shadows and some angle.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Orval Fairbairn wrote:
In article ,
"Peter Webb" wrote:

Surely the correct title for this post would be:

"It may be possible for future orbital surveillance satellites to exceed 1
inch resolution", as this appears to be the claim you are actually making.

It would take one HELL of a focal length!

It's not like you'd be limited for space!

Orval Fairbairn wrote:

It would take one HELL of a focal length!


Think of that hypothetical gizmo... you could pull it off looking at the
Moon, or another atmosphere-free body.
But peering down though sixty miles of turbulent atmosphere?
It would make more sense to use radar.

Pat