Re: Proposal for an American Space-Based Economy


A Gamma Ray Imaging Spectrometer (GRIS) is a device for
studying spectrographic images of gamma ray activity
throughout the universe. Since there is such a wide
spectrum of gamma radiation, there needs to be a defined
set of parameters for narrowing the spectrum down to
useable frequency, magnitude, and count that would image
the precious metal content of an Aten asteroid with a
known location and orbit.

First, the energy level in KeV needs to be established for
the atomic transition level of a gold or platinum molecule
in the gamma ray frequency. There are some interesting graphs
related to GRIS used by NASA that are related to GRIS energy
resolution (Fall/1995) that lists the Frequency Wide Harmonic
Magnitude in KeV from 0KeV to 10KeV verses the energy level
from 0 to 8000KeV, or GRIS GAIN energy calibration accuracy
which lists the error in KeV from -1KeV to 1KeV verses the
energy in KeV from 10KeV to 104KeV, or GRIS continuum back-
ground that is the continuum background in counts from
..00001 to 1 cm^-3 sec^-1 MeV^-1 per energy from 10^-2 MeV
to 10 MeV range. The GRIS background spectrumshows counts
from .00001 to 10 cm^ -3 sec^-1 MeV^-1 per energy from 10
KeV to 10,000 KeV range. Thus there are limitations to the
observable gamma field that need to be referenced when
designing narrowband filters for the desired frequency,
magnitude, and count parameters.

Centrifuge Processing of Extraterrestrial Precious Metal

A rotating cylindrical vessel of volume V with incoming
regolith at inlet #1, and hot dilute NaCN and H2O at inlet
#2 is designated as the feed q_j, which is equal to
( q_NaCN + q_regolith ). The inner centrifuge cylinder
is immersed in the outer centrifuge cylinder of annular
volume V_c, which contains recirculated heated machine
oil at temperature T_hf at a flow rate q_h. The outgoing
pipe contains the mixture of products and the remnant
of the reactants at a flowrate of q = q_NaCN + q_regolith
+ q_reactants . Thus the volume V remains constant.

Some Theory on Precious Metal Spectroscopy

Actual atoms scatter, as they absorb, at frequencies
connected with quantum transitions between energy levels.
The spectra resulting from the excitation of inner electrons
provides a connecting link between optical and gamma ray
spectroscopy. Only one electron needs to alter its quantum
numbers in order to reach the excited state from the ground
state. When this happens, a continuous absorption spectrum
joins the series limit just as a normal series, and also
corresponds to ionization leaving not only the outer shell
of the molecule, but also to the excitation of shells lying
still farther in.

Compton scattering causes the scattered X-ray to be a
different wavelength than the incident X-ray. For this
reason, one needs to know the location of the original
X-ray source and the angle of reflection off the surface
of the asteroid, but not necessarily. If an observer had
a known location, and the asteroids position could be
calculated precisely at one time, with scattered wavelengths
observed, and at a later time, both observer and asteroid
were known withscattered wavelengths observed, the
scattered frequencies could be correlated with existing
transition energies and frequencies of the precious metal,
with maximum likelihood of incidental angle. Of course,
this would depend on initial educated guesswork,
involving the exact intensity, frequency, and location
of existing galactic gamma ray source (e.g. from GRB 971214,
12 billion light years away!)

Gamma ray spectroscopy is more suited to locating precious
metal asteroids since gamma rays can penetrate into the
interior of the asteroid unlike infared spectrometers.
The resolution is also much better, with finer spectro-
graphic data being demonstrated much more dramatically
than with the infared type.

The absorption band varies according to how the intensity
of reflection varies with wavelength. For this reason,
we have different states of metals as they would exist
in asteroids.

Check out the NIST Atomic Spectroscopic Database
(Version 1.0) for information on the spectrum of the
different states for each element - There are hundreds
of states for aluminum! Other sources indicate that
spectral emissivity tends to increase with decreasing
wavelength. The normal spectral emissivity for Platinum
at 1 meter wavelength is approximately 0.25 at 1217 degrees
Kelvin.

However, this emissivity is for polished platinum. IMO the
emissivity would be higher (0.05 maximum variation) for
a less smooth surface. Still, a lower surface temperature
(less than 1217 K for platinum) would tend to raise the
spectral emissivity variation a maximum of 0.025. The
total maximum variation in spectral emissivity would
then be about 0.075. Added to the normal spectral
emissivity would equal 0.25 + 0.075 = 0.325.


American

[1]

Space Resources - Breaking the Bonds of Earth by John S. Lewis and
Ruth A. Lewis, Columbia University Press, Copyright 1987

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