Viking Lander: subsurface water analyzing probe. [Mars subsoil]

Technical Report · Wed Oct 01 00:00:00 EDT 1969

DOI:https://doi.org/10.2172/5181244· OSTI ID:5181244

Simmons, G J

A small terradynamic (soil penetrating) vehicle, to be released from the Viking Lander at an altitude of between 5000 and 6000 feet before the terminal descent on the vernier rockets begins, will implant a sensor package 3 to 5 feet beneath the surface to measure water content of Mars subsoil. As it penetrates the soil, the vehicle separates into a probe which carries the primary instrumentation and a tail section which contains the power supply, secondary sensors, and transmitter and antenna assembly. The two sections remain linked by a hard wire umbilical which provides for power and data flow between the sections. After impact, a soil moisture subsystem would be activated to gather approximately 100 milligrams of soil at the depth of the penetrating probe. After the mass of the sample is measured, its water content would be determined by heating in a sealed known volume and measuring the dew point of the resulting water vapor with a specular reflection dew point indicator. The penetrating probe and the tail section each contain a pair of aluminum oxide hygrometer elements and one sensistor temperature sensor which, on request by an on-board programmer will measure temperature and absolute water content of the vapor phase in equilibrium with the surrounding soil. Once each 8 hours, the digitized output of the sensors would be transmitted by the RF link to the Lander. This apparatus is expected to measure the water vapor in equilibrium with the soil water in concentrations as low as 0.01 microgram per liter at --60/sup 0/C and absolute soil water in amounts as small as 10 micrograms per gram of soil. A radioisotope power supply would provide an expected life for this instrumentation package in excess of the proposed 90-day mission for the Mars Viking Lander.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• OSTI ID: 5181244
• Report Number(s): SC-SR-69-737
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
MARS PLANET
SOILS
MOISTURE GAGES
DESIGN
DATA ACQUISITION
DEW POINT
HUMIDITY
HYGROMETRY
MOISTURE
POWER SUPPLIES
PROBES
SNAP BATTERIES
VAPORS
DIRECT ENERGY CONVERTERS
ELECTRONIC EQUIPMENT
FLUIDS
GASES
MEASURING INSTRUMENTS
PLANETS
RADIOISOTOPE BATTERIES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
440300* - Miscellaneous Instruments- (-1989)