Data was obtained on silicone-bonded fiberglass, isocyanurate foam, and two dozen other insulators. Materials were selected to withstand heat sterilization, outer space, and the Martian atmosphere. Significant environmental parameters were vibration, landing shock, and launch venting

Conti, J. C.

Mcgee, J. V.

Mcpherson, J. I.

Wilbers, O. J.

English

NASA Technical Reports Server

January 1978
	 B73-10020 
•	 NASA TECH BRIEF 
NASA Pasadena Office
P 
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V 
Evaluation of Thermal Insulation Materials 
A study of thermal insulation materials and their 
potential application in the Viking-1973 soft-lander 
mission to Mars has resulted in the accumulation of 
a significant body of data on a silicone-bonded fiber-
glass, an isocyanurate foam, and two dozen other 
types of insulators. The data provide useful guide-
lines for the design of thermal insulation systems for 
everyday applications. 
The candidate thermal insulation materials used 
in the .study are commercially available; they were 
selected on the premise that they should withstand 
heat sterilization, outer space, and the Martian atmo-
'- sphere. The study was performed in five phases: (1) 
Selection of candidate materials; (2) Definition of 
specific tests to simulate the Mars mission environ-
ments; (8) Selection of two materials on the basis of 
results of screening tests; (4) Definition and design of 
applicable insulation systems; (5) Subjecting the se-
lected materials and insulation systems to significant 
Mars mission environmental conditions. 
The environmental parameters considered most sig-
nificant were heat sterilization (185°C for 884 hours 
in dry nitrogen), vibration, landing shock, and ex-
posure to the Martian surface environment; launch 
venting was also identified as a critical parameter. 
Rapid screening tests were used for determining re-
sistance of candidate materials to heat sterilization; 
in a thermogravinietric apparatus, samples were 
heated at 50 per minute to 285°C (100°C above the 
heat sterilization temperature) in order to accelerate 
long-term changes which might occur during an 
actual 884-hour sterilization cycle. The thermal dif-
fusivity test involved transient heating of the materials 
by a milliwatt heater in the center of a 15-cm cube of
the sample; the power input was selected to provide 
a heater temperature rise of 10°C in 12 minutes. The 
thermal conductivity was derived from analysis of the 
temperature rise per unit heat input; the tests were 
performed in vacuum, at ambient atmospheric pres-
sure, and in a simulated Martian atmosphere. 
Interpretation of the results of the screening tests 
led to the selection of an isocyanurate foam and a 
silicone-bonded fiberglass for further study; accord-
ingly, these materials were fabricated into insulation 
system modules (ISM) of the forms which prior study 
had indicated to be optimum for the nature of the 
insulating material. The foam material was bonded 
into a foam sandwich structure which took advantage 
of the load-carrying capability of the foam to provide 
a structure weight half as large as that required for 
the silicone-bonded fiberglass. Bonded fiberglass was 
selected over unbonded material because its inherent 
resiliency allowed a loose lay-up in an ISM design 
with a beaded and corrugation-stiffened structure. 
Insulation system modules were exposed to the ac-
tual sterilization test (135°C, 884 hours) and to a 
thermal performance test (relative heat loss in vacuum 
and in a Martian atmosphere). Unfortunately, the 
foam ISM fragmented during a preliminary pump-
down of the test chamber even though foam samples 
had successfully withstood numerous pumpdown 
cycles in the screening tests. The remaining silicone-
bonded fiberglass ISM successfully underwent the 
launch vibration test [16.1 g (rms)], the landing shock 
test [120-g pulse for 12.8 msec], and an exhaustive 
thermal conductivity test covering the predicted range 
of Martian atmospheric pressure, temperature, and 
gas compositions.
(continued overleaf) 
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https://ntrs.nasa.gov/search.jsp?R=19730000020 2020-03-17T06:38:12+00:00Z
NASA CR-109612 (N70-25585), Martian Soft 
Lander Insulation Study. 
Source: 0. J
. 
Wilbers, J . C. Conti,
J . V. McGee, and J . I. McPherson of
McDonnell Douglas Corporation
under contract to
NASA Pasadena Office 
(NPO-11586)
Note: 
The following documentation may be obtained 
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Springfield, Virginia 22151 
Single document price $6.00 
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B73-10020	 Category 04


Evaluation of thermal insulation materials

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