Brief discriptions of the following 13 experiments are included: ultrahigh vacuum petrology facility; artificial comet free flyer; artificial comet (tethered); cosmic dust detector; cosmic dust collector; dust collection using tethered satellites; artificial magnetosphere; microgravity petrological studies; slitless ultraviolet spectrometer; orbital determination and capture experiment (ODACE); high velocity sputtering of amorphous silicates; particle release experiments; and calibration of gamma and X-ray remote sensingprobes

Corso, G.

Devincenzi, D.

Duba, A.

Freeman, J.

Lopez, R.

Nuth, J. A., III

Stephens, J.

Strong, I.

Wolfe, J.

English

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5.0 REPORT ON OPPORTUNITITES AND/OR TECHNIQUES FOR HIGH-CALIBER
EXPERIMENTAL RESEARCH (OTHER) PROPOSALS FOR SSPEX
Joseph A. Nuth (Chairman), NASA Headquarters; George Corso, Northwestern
University; Donald DeVincenzi, NASA Headquarters; A1 Duba, Lawrence Livermore
Laboratory; John Freeman, Rice University; Ramon Lopez, Rice University; James
Stephens, Jet Propulsion Laboratory; Ian Strong, Los Alamos National
Laboratory; John Wolfe, San Jose State University
5.1 Introduction
Unlike the previous summary reports, the only unifying factor among the
experiments discussed in this section is that they are all unique
Opportunities and/or Techniques for High-callber Experimental Research
TOTHER!). Many of th_ investlgatlon_ discussed iF this report_ere submitted
to the SSPEX workshops as abstracts, although several additional experiments
have been added as a result of workshop discussions. Despite the enormous
diversity of the investigations proposed, several common concerns have emerged
regarding the availability of "standard" items.
Several people expressed a desire for one or more windows. These can be
located either in the lab module, as a transparent hatch cover or in the
habitability module. In general, these would not be in constant use -in fact
they probably would be used only rarely. Windows should "look" both
"upstream" and "downstream" from the station and should also be available for
Earth and "deep space" views. Because they would be used only occasionally,
positioning behind mobile equipment racks in the lab module could be
considered.
Another requirement of several of the proposed investigations is the
development of automated tether systems; if possible, small (<500 m) tether
systems should be able to travel along tracks spanning much of the station.
Another possibility is the attachment of small tethers to one or more remote
manipulator arms(s) or to one or more deployable booms. A boom which can hold
a shield several hundred meters "in front of" the station (or above it) in
order to avoid local contamination is a necessity for several experiments. Of
course, investigators assume some astronaut EVA time for limited servicing,
equipment and/or sample changes, as well as deployment or retrieval of the
experiment.
One additional factor which requires thought is the degree of overlapping
needs or use of common equipment for very different experiments. For example,
the experiment proposed by Walker could provide a very large shield to create
the ultra high vacuum required by Duba or Nuth (see abstracts). Could such an
ultrahigh vacuum facility be useful to a larger community? Could the small
tethers required by Lopez be used to deploy and retrieve Stephens' artificial
comet? Could the tall gun proposed for the craterlng experiments be used to
fire projectiles into the atmosphere at speeds greater than 25 km/s and thus
create an artificial meteor? Could the dust collectors proposed by torso be
mounted on all tethered upper atmospheric research satellites?
Along these same lines, mutual interferences among experlments--or Space
Station operatlon--must be considered. As examples, could particles released
by Strong or Stephens interfere with the collection efforts of Walker? How
many tethers could be deployed around the station, and in which directions,
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before they constitute a navigational hazard? How large a disturbance to
microgravity experiments would result by firing projectiles into the upper
atmosphere (or doing cratering studies)?
Many of the experiments described in the abstracts are in the "formative"
stage of development. Still, all of the proposals utilize the space station
environment for investigations which could never be performed on Earth. None
are suitable for flight on the KC-135, although several could be developed as
Shuttle experiments. In some cases (e.g. Strong ([2) and Williams (8))
development of Shuttle experiments is under way.
The following includes brief descriptions of 13 experiments; 9 of these
were presented to workshop participants. Another is mentioned in the "Banks"
Report as a candidate for IOC. Two more experiments were discussed by
participants at the workshop, as an outgrowth of other experiments already
under discussion. A final "calibration" experiment was discussed by Boynton
at an earlier meeting. Considering the number and variety of Planetary
Science experiments which keep emerging these should be considered as the
vanguard of many more proposals.
5.2 Specific Experiments
Ultrahigh Vacuum Petrology Facility
Duba proposes placing a large (>3 m diam.) shield in front of (or above)
the Space Station. The region behind the shield would experience a very low
pressure due to the shield "sweeping" ambient gas away as it travels at
orbital velocity (8 km/s). Pressures of 10-15 torr of H and He seem possible,
while atom partial pressures less than 10-20 torr could be obtained. In this
very low pressure region Duba proposes to study the high temperature
metamorphism of carbonaceous chondrites. In particular he proposes to measure
the variation in the electrical conductivity of the sample as a function of
both time and temperature in order to test the theory that the observed
differences in composition of asteroids (as a function of their orbital
seml-major axis) could be due to electromagnetic heating during the early
history of the solar system.
Artificial Comet-Free Flyer
Stephens proposes placing several large "chunks of ice" into orbit in
which finely dispersed dust particles and several radio thermometers have been
frozen. The object of the experiments is to determine the dependence of the
temperature structure within the comet on both the composition and
concentration of the dust. In particular, he wants to test the hypothesis
that a significant quantity of volatiles could be trapped inside of "dead"
comets and protected by a highly efficient insulating layer of "hardened",
extremely porous dust.
Artificial Comet - Tethered
In this experiment Stephens proposes to tether materials similar to those
described in (2) in order that the "comets" can be recovered for later study
on earth. In this way the thickness of the insulating layer, as well as its
structure could be determined and correlated with its "insulating efficiency".
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An additional advantage of tethered comets is observation of the development
of the dust plume as a function of exposure to various levels of solar
insulation.
Cosmic Dust Detector
Wolfe proposed placing a relatively large (I-2 m2) acoustic impact
detector on the space station in order to measure the long term anlsotropy of
the flux of cosmic dust particles. Using acoustic spectral analysis he feels
that it is possible to derive some compositional information about the
impacting particle as well as its directions and momentum. In this way,
information about both the flux and composition of asteroldal, cometary and
interstellar particles might be gained.
Cosmic Dust Collector
In this experiment, Wolfe proposes placing an electrostatic decelerator
on the space station. The detector is capable of decelerating particles
entering the collector with velocities as high as 25-30 km/s, and will
simultaneously reject relatively slow moving debris in the vicinity of the
station. Periodic return of the collector surface would allow the recovery of
pristine cosmic dust samples which have not been contaminated by the earth's
atmosphere. Such materials would constitute an extremely valuable resource to
the exobiology community.
Dust Collection using Tethered Satellites
Corso proposed outfitting satellites lowered into the Earth's upper
atmosphere with cosmic dust collectors. In this way he hopes to collect large
numbers of relatively uncontaminated particles soon after their arrival. In
fact, using this method it could be possible to determine to within a few
hours the time of arrival of particular particles and thus correlate them with
known meteor showers. Such a collection would be complementary to both the
stratospheric and space station efforts.
Artificial Magnetosphere
Lopex proposes suspending a strong magnet from a tether approximately 200
m or so above the space station in order to create an artificial
magnetosphere. Diagnostic probes could be suspended on mobile tethers
downstream from this magnet to probe its interaction with the ambient plasma.
In addition ionic tracers such as Barium could be released "upwind" at will.
A series of non-tethered experiments might also be necessary to probe the
effect of the tether on the plasma sheath.
Micro-gravity Petrological Studies
Williams and Lofgren have constructed a highly efficient furnace system
which accurately controls the redox conditions under which the experiments are
performed. They propose to fly this system aboard space station in order to
study the effect of cooling rate on the resulting texture of chondrule-like
materials. Efforts to study this problem in I g are frustrated by the
settling of early condensates from the melt and, in some cases, by buoyancy
driven convection.
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Slitless UV Spectrometer (Construction and Calibration)
Wdowiak, et al. have proposed the construction of a Slitless UV
Spectrometer to obtain meteor spectrap and especially to determine the
relative ratios of the blogenlc elements in these meteors. If the craterlng
community (or SDI) places a tall gun (or similar facility) into orbit it might
be possible to fire projectiles of known composition into the earth's
atmosphere along well determined trajectories at speeds approaching 25 km/s.
Such a facility not only could be used to accurately calibrate the
spectrometer but could also be used to test models of atmospheric entry
phenomena.
ODACE - Orbital Determination and Capture Experiment
Walker proposed building a large dust collector (I0 m x 10 m) with the
capability to determine the velocity of the impacting particle. When
"interesting" particles are observed the small cell (I0 cm x I0 cm) containing
the particle would be returned to earth for study. At this time it might be
possible to precisely determine the orbital parameters of the particle as well
as a significant amount of compositional and structural information. A cosmic
dust collector is mentioned in the Bank's Report as a high priority item for
IOC.
High Velocity Sputtering of Amorphous Silicates
This experiment grew out of discussions with A1 Duba and others at the
workshop. If we put a hole in the middle of A1 Duba's shield (which could be
closed off -of course) then this would be an excellent source of 7-8 km/s
oxygen, nitrogen, helium and hydrogen atoms with which to carry out sputtering
experiments. It might also be possible to charge these atoms using an
electron gun so that one could electromagnetically separate the beam into its
atomic components. This device could serve as a useful experimental facility
for material science experiments. In particular, Nuth wants to study the
metamorphism of amorphous iron and magnesium silicates exposed to such a beam
in order to better understand the processing of these materials via shocks in
the interstellar medium.
Particle Release Experiments
Strong and coworkers have not yet established a definitive set of
particle release experiments to be performed from the space station, in part
because they have not yet carried out a planned series of releases from the
space shuttle. These experiments will take advantage of the unique
observational capabilities of the AMOS Facility in Hawaii in order to measure
various properties of the released particles such as the scattering,
absorption and extinction efficiencles as well as the speed with which the
particles become aligned in the earth's magnetic field. The results of these
early shuttle experiments will determine the particular experiments which best
utilize the unique opportunities afforded by the space station.
Calibration of Gamma and X-ray Remote Sensing Probes
Boynton mentioned this possibility at a previous meeting and it is
included here for completeness. He suggests that the best place to calibrate
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a remote sensing tool such as a gamma ray or x-ray fluorescence spectrometer
is in the space environment. On earth, only single llne gamma ray sources are
available for use as excitation probes for natural samples. Similarly, no
continuous "natural" x-ray spectra are available with which to calibrate x-ray
fluorescence detectors. Much better instrument calibrations would be
available if one could observe transported natural samples such as basalts,
granites and various ices - or even observe various parts of the station
itself prior to launch to their ultimate planetary targets.
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Report on opportunities and/or techniques for high-caliber experimental research (other) proposals for SSPEX

Report on opportunities and/or techniques for high-caliber experimental research (other) proposals for SSPEX

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