🚀 go-pugleaf

On Aug 7, 3:19 pm, Jon Kirwan <j...@infinitefactors.org> wrote:
> On Tue, 7 Aug 2012 05:23:52 -0700 (PDT), dp <d...@tgi-sci.com>
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> >On Aug 7, 5:11 am, Jon Kirwan <j...@infinitefactors.org> wrote:
> >> ...(Most of my work was in the
> >> visible, near UV, and near IR -- but for very different
> >> applications.) I still have some decent setups here and I've
> >> designed some devices that can be made for only a few
> >> dollars, and wavelength calibrated for $8 more, so that high
> >> school students could actually built their own real-world
> >> equipment that could genuinely "do science" and meet
> >> calibration standards. No intensity calibration, though,
> >> sadly. That costs money to do. (Unless you have a suggestion
> >> about how to do it on the cheap?)
>
> >Oh no, I could not possibly have a suggestion. My spectrometers
> >don't seem to have an overlapping wavelength range with yours,
> >mine are xray/gamma. I am practically clueless when it comes to
> >those in the UV and below range, mine generally count single
> >photons.
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> For all those reasons, that is why I would LOVE to see the
> "optics" (and the schematics, as well.) Totally new area for
> me to learn about. In my region, it's all about electron
> transitions -- and no molecular dissassociation.
>
> I'd expect you'd count single photons at those energies --
> just one probably creates quite a shower to deal with. I'd
> like to know, in practice, how one measures the energy.
>
> Also, in space there is a serious problem with "brown crud",
> which is smashed, charged particles that come from the
> satellite's own fabrication scattered into space, which
> because it is charged comes back to the spacecraft at some
> later time, but sticks elsewhere (not where you want it.) I
> don't know if there is a problem with this on Mars -- there
> is an atmosphere of sorts. But I'm curious just the same if
> there is an accumulation problem and how it is dealt with.
>
> >Efficiency calibration is costly on those for gamma, too,
> >though - the calibration source costs thousands. The rest, hm,
> >has become much less expensive since the release of the
> >netmca-3 (one can still spend tens of thousands on it but
> >does not have to any longer).
>
> Now THAT I totally believe. I probably couldn't afford it.
> But I still could learn.
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> >I would be curious what gamma spectrometry the thing is
> >carrying on board, too (if any, but likely so). Unlikely
> >HPGe, but then who knows, Mars is a cold place, they may
> >have figured some practical way to cool things down to
> >about liquid nitrogen.
>
> Well, they certainly don't have much atmospheric pressure to
> worry about.
>
> Which reminds me of another thing. How do they convect the
> internally generated heat away. I recall hearing about
> multiple power systems, operating around 32V at near 2A. More
> than one. This power must be convected/conducted away -- no
> way they want to radiate it. I wonder if they push it
> (costing more heat) towards a vane or arm and drag it around
> on the surface to get rid of it?

The atmosphere won't help much.

Why not?  Thermal conductivity of air is pretty much constant till you
get below 1 Torr or so.  Wiki says the mean pressure on mars is about
0.1 psi, which is ~5 torr.

Re spectrometer calibration:  We had this "black body" source. (from
Ortec?)  That could be used for intensity calibration.  PITA though.

But maybe you could do something on the cheap with a tungsten light
bulb.

George H.
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