Experiments that explore chemical and physical aspects of volatilization reactions that require the microgravity and low pressure in or near the projected Space Station are proposed

Anderson, D. M.

Gilbert, M. C.

Hajash, A.

Hoskins, E.

Popp, R. K.

English

NASA Technical Reports Server

VOLATILIZATION-DEVOLATILIZATION REACTIONS 
1 Gilbert, M.C. lt2, Anderson, D.M. I, Hajash, A. , 
Hoskins, E ., Popp, R.K. 1 1 
'Program in Petrology and Geochemistry, Department of 
2Coordinator for Cosmochemical Experimentation 
Geology, Texas A&M University, College Station, TX 77843  
Experiments that explore chemical and physical aspects of 
volatilization reactions that require the microgravity and low 
pressure in or near the projected Space Station are proposed. 
Chemical Aspects: 
We envisage a program of experiments utilizing near zero 
pressure conditions available with molecular shield technology 
(see Duba, Electrical Conductivity. . . ,this report) attached to 
the Space Station to study: 
a) reaction rates of mineral devolatilization. Two mineral 
groups, the amphiboles and micas (and all the sheet 
silicates in general) are primary carriers of H20 and F 
in rock-forming processes. The important reaction type: 
hydrous solid = anhydrous solids + vapor, studied over a 
range of temperatures from 130OoC to as close to 
space-ambient temperature as reaction rates can be 
measured will provide fundamental limiting data on the 
energetics of the crystalline state. The amphiboles and 
micas can be synthesized in their pure OH- and F-forms 
so that comparative data of great value could be derived 
from experimental studies in the Space Station. The 
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b) 
Physical 
time frame for the experiments will be a few days to 60 
days. Gravity control is not essential, but pressures 
less than 10 -lo Pa are required. 
the equilibrium vapor pressure of volatile-bearing 
mineral species. Completing equilibrium studies at very 
low pressures would allow fixation of the reaction 
boundaries - expressed, for example, in conventional 
fH20-1/T diagrams - in parts of the diagrams not 
accessible on Earth. These experiments would utilize 
pressures from station-ambient preferably to < 10 -lo Pa. 
Aspects : 
We suggest a program focused on the precipitation, growth, and 
recrystallization of various cosmically important minerals, 
particularly ices of H 2 0  and C02,  and mixtures of these, to 
study: 
a) textural patterns and their evolution with sequential 
modification of boundary conditions. Meteorites, and 
especially asteroidal material subsequently to be 
obtained, can provide information on their formation 
histories as well as that of the solar system through 
detailed textural studies. These studies will have to 
be calibrated against synthetically produced textures 
from the Station experiments. 
These experiments would need both controlled gravity 
(-10'5g) and access to pressure ranges from 
station-ambient (-1 bar) to space ambient (molecular 
shield to obtain <lo 
60 days. Slowly rotating furnaces would probably 
prevent crystal settling conditions for such long 
periods. 
Pa) over time-scales of 1 day to -10 
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scattering, absorption, and reflectivity of radar and 
other wavelength radiation. Ices and particulate 
silicates are important constituents of dispersed 
planetary matter. The proposed measurements are to 
provide baseline data for all our remote sensing studies 
of these materials, particularly fragile aggregates of 
such material which could not be synthesized or 
maintained under 1 g. Initial experimental requirements 
are the same as under the sections above. Subsequent to 
synthesis radiation sources and detectors on or near for 
comparable analysis the station will be required in some 
cases before returning samples to earth. 
Technical Requirement Summaries: 
Volume: 2 m3 for the first three experiments 
Mass : Estimated 10-30 kg for assembly 
Temperature: Space-ambient to 130OoC 
Pressure : Space-ambient (<lo -lo Pa) to station ambient 
g-level : 
Duration : 
to g for certain experiments. 
Rotation of the sample may be required to 
offset effects of density aggregation on 
longer (month +) experiments. 
Experiments will last from about 1 day 
(possibly even hours at T > 1000°C) to 60 
days. 
Instrumentation: Power controllers, continuous temperature and 
pressure measurements down to the 
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space-ambient, gas analysis 
(mass spectrometry), gas pressure controllers 
and flow rate regulators. 
Crew Interaction: Conditions during experiments can be 
controlled automatically, but sample changing 
and periodic human monitoring required. Some 
physical measurements will have to be 
performed by crew. 
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Volatilization-devolatilization reactions

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