A $5 radiometer on a satellite should be accurate to several decimal
places over at least one important band width. Other coatings could
be calibrated to work for the rest of the spectrum.

All we need is to be accurate to the nearest watt/m^2. What's the big
holdup in determining net increases in incoming radiation energy?


Bret Cahill

Bret Cahill wrote:
>
> A $5 radiometer on a satellite should be accurate to several decimal
> places over at least one important band width. Other coatings could
> be calibrated to work for the rest of the spectrum.
>
> All we need is to be accurate to the nearest watt/m^2. What's the big
> holdup in determining net increases in incoming radiation energy?

The data are politically unacceptable. Studies are being conducted to
create telemetry dynamically sensitive to the needs of liars and
criminals.

Uncle Al says, "Where there are no corrections needed there is no
Official Truth to be had."

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz4.htm

Bret Cahill wrote:
> A $5 radiometer on a satellite should be accurate to several decimal
> places over at least one important band width. Other coatings could
> be calibrated to work for the rest of the spectrum.
>
> All we need is to be accurate to the nearest watt/m^2. What's the big
> holdup in determining net increases in incoming radiation energy?
>
>
> Bret Cahill
>

Perhaps consider the following article:

> http://www.nature.com/nature/journal.../410355a0.html

Greetings,

Q

--
The difference between us and the Titanic is the band.

A $5 sensor??? A 4.40 screw is more than that when you havee to put it into
space!

--
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net

On Jan 10, 1:56*pm, Bret Cahill <BretCah...*peoplepc.com> wrote:
> A $5 radiometer on a satellite should be accurate to several decimal
> places over at least one important band width. *Other coatings could
> be calibrated to work for the rest of the spectrum.
>
> All we need is to be accurate to the nearest watt/m^2. *What's the big
> holdup in determining net increases in incoming radiation energy?
>
> Bret Cahill

Space is a tough place. Solar flares (charged particles), harsh solar
radiation unfiltered by the earth's atmosphere, and the general lack
of a repairman make for a harsh environment that degrades equipment.
The fact that so many of the GPS Block IIA satellites are still
working is a testimony to the folks who built them.

Here are some problems with CERES Aqua as documented on slide 6 here:
http://aqua.nasa.gov/doc/presentatio...icki_CERES.ppt

"CERES Mirror Attenuator Mosaic solar diffusers showed coating
degradations in first two years on orbit. Weakened initial stability
confirmation.
--Improve coatings on FM-5.

CERES FM-4 SW channel failed March 30, 2005. Total and Window
channels remain nominal. Obtained primary second instrument data
requirement: > 2 years of rotating azimuth.
--But if CERES FM-3 fails, will need to derive CERES SW on FM-4 using
MODIS/CERES merged at night for LW, and then apply in daytime for
Total - LW = SW.

All CERES instruments have shown SW optics transmission loss when in
rotating azimuth mode (1 to 2% over 5 years).
--Physical model in testing, Rev1 released to correct all-sky and
clear-ocean. Edition 3 in 2007 will begin more rigorous correction
for all scene types. All CERES instruments now in crosstrack to
eliminate further changes.

Data fusion more difficult than anticipated: climate accuracy "

If you haven't worked with satellites it may be hard to appreciate the
very real challenges involved.

--Mike Jr.

On Jan 10, 10:56*am, Bret Cahill <BretCah...*peoplepc.com> wrote:
> A $5 radiometer on a satellite should be accurate to several decimal
> places over at least one important band width. *Other coatings could
> be calibrated to work for the rest of the spectrum.
>
> All we need is to be accurate to the nearest watt/m^2. *What's the big
> holdup in determining net increases in incoming radiation energy?

A $5 radiometer that's sensitive to say 500 nm in the blue-green
would do fine, yes? Keep in mind that it will have to survive being
illuminated by the sun's total spectrum, not just that one narrow
line. You know, all the energetic protons and electrons, gamma and x-
rays, hard UV and so on that are very hard on electronics and optics.
Not to mention occasional micrometeoroids or stray toolbelts at
several miles per second, and the occasional solar flare, which can
include huge EMP.

Filter it you say? Fine, but remember your filter must survive all
the above _and_ maintain its transmittance at the specified line over
its lifetime without degrading, which would corrupt the sensor's data.


Mark L. Fergerson

> > A $5 radiometer on a satellite should be accurate to several decimal
> > places over at least one important band width. *Other coatings could
> > be calibrated to work for the rest of the spectrum.
>
> > All we need is to be accurate to the nearest watt/m^2. *What's the big
> > holdup in determining net increases in incoming radiation energy?
>
> * A $5 radiometer that's sensitive to say 500 nm in the blue-green
> would do fine, yes? Keep in mind that it will have to survive being
> illuminated by the sun's total spectrum, not just that one narrow
> line. You know, all the energetic protons and electrons, gamma and x-
> rays, hard UV and so on that are very hard on electronics and optics.
> Not to mention occasional micrometeoroids or stray toolbelts at
> several miles per second, and the occasional solar flare, which can
> include huge EMP.
>
> * Filter it you say? Fine, but remember your filter must survive all
> the above _and_ maintain its transmittance at the specified line over
> its lifetime without degrading, which would corrupt the sensor's data.
>
> * Mark L. Fergerson

Just expose a piece of plastic up there for a month or a year, bring
it back and inspect the damage.

There must be a gazillion dirt cheap ways to determine the radiation
balance to any accuracy necessary.


Bret Cahill

On Jan 11, 10:52*am, Bret Cahill <BretCah...*peoplepc.com> wrote:
> > > A $5 radiometer on a satellite should be accurate to several decimal
> > > places over at least one important band width. *Other coatings could
> > > be calibrated to work for the rest of the spectrum.
>
> > > All we need is to be accurate to the nearest watt/m^2. *What's the big
> > > holdup in determining net increases in incoming radiation energy?
>
> > * A $5 radiometer that's sensitive to say 500 nm in the blue-green
> > would do fine, yes? Keep in mind that it will have to survive being
> > illuminated by the sun's total spectrum, not just that one narrow
> > line. You know, all the energetic protons and electrons, gamma and x-
> > rays, hard UV and so on that are very hard on electronics and optics.
> > Not to mention occasional micrometeoroids or stray toolbelts at
> > several miles per second, and the occasional solar flare, which can
> > include huge EMP.
>
> > * Filter it you say? Fine, but remember your filter must survive all
> > the above _and_ maintain its transmittance at the specified line over
> > its lifetime without degrading, which would corrupt the sensor's data.
>
> > * Mark L. Fergerson
>
> Just expose a piece of plastic up there for a month or a year, bring
> it back and inspect the damage.

And then attribute it to what, specifically?

> There must be a gazillion dirt cheap ways to determine the radiation
> balance to any accuracy necessary.

No, you'd need to do Earth-surface comparison studies, exposing
identical samples of black plastic to every kind of radiation the
stuff you sent up was exposed to, but in isolation; this piece gets X-
rayed, that piece gets hard UV, and so on, then correlate all the
separate damage indicators and compare with the orbited sample.

I think you'll go over that $5 budget rather quickly.


Mark L. Fergerson

> > > > A $5 radiometer on a satellite should be accurate to several decimal
> > > > places over at least one important band width. *Other coatings could
> > > > be calibrated to work for the rest of the spectrum.
>
> > > > All we need is to be accurate to the nearest watt/m^2. *What's the big
> > > > holdup in determining net increases in incoming radiation energy?
>
> > > * A $5 radiometer that's sensitive to say 500 nm in the blue-green
> > > would do fine, yes? Keep in mind that it will have to survive being
> > > illuminated by the sun's total spectrum, not just that one narrow
> > > line. You know, all the energetic protons and electrons, gamma and x-
> > > rays, hard UV and so on that are very hard on electronics and optics.
> > > Not to mention occasional micrometeoroids or stray toolbelts at
> > > several miles per second, and the occasional solar flare, which can
> > > include huge EMP.
>
> > > * Filter it you say? Fine, but remember your filter must survive all
> > > the above _and_ maintain its transmittance at the specified line over
> > > its lifetime without degrading, which would corrupt the sensor's data..
>
> > > * Mark L. Fergerson
>
> > Just expose a piece of plastic up there for a month or a year, bring
> > it back and inspect the damage.

> * And then attribute it to what, specifically?

Whatever amount of radiation damaged a similar target by that amount.

> > There must be a gazillion dirt cheap ways to determine the radiation
> > balance to any accuracy necessary.

> * No, you'd need to do Earth-surface comparison studies, exposing
> identical samples of black plastic to every kind of radiation the
> stuff you sent up was exposed to, but in isolation;

We really just need to know _changes_ from year to year.

> this piece gets X-
> rayed, that piece gets hard UV, and so on, then correlate all the
> separate damage indicators and compare with the orbited sample.

Sounds like the rocket will be cheaper . . .

> * I think you'll go over that $5 budget rather quickly.

$5 was for something with a moving part.

Using several different materials for different regions of the
spectrum could easily be less than $5.

How big does the target _need_ to be?


Bret Cahill

Mike Jr wrote:
> On Jan 10, 1:56 pm, Bret Cahill <BretCah...*peoplepc.com> wrote:
>> A $5 radiometer on a satellite should be accurate to several decimal
>> places over at least one important band width. Other coatings could
>> be calibrated to work for the rest of the spectrum.
>>
>> All we need is to be accurate to the nearest watt/m^2. What's the big
>> holdup in determining net increases in incoming radiation energy?
>>
>> Bret Cahill
>
> Space is a tough place. Solar flares (charged particles), harsh solar
> radiation unfiltered by the earth's atmosphere, and the general lack
> of a repairman make for a harsh environment that degrades equipment.
> The fact that so many of the GPS Block IIA satellites are still
> working is a testimony to the folks who built them.
>
> snip
> --Mike Jr.

I second this. I worked on a lite-sat program that originally set out to
use COTS (commercial off-the-shelf) equipment as much as possible. It
was very disappointing to find how little of it met environmental
requirements. When I read the original post, that was the first thing
that entered my mind. Even the cost of testing the part to the space
and launch environment would be orders of magnitude beyond the five bucks.