1612. Small Mass Measurement Instrument – for Measuring Weight Under Weightless Conditions

Paper

Abstract

Animal metabolic function tests and other experiments to be conducted by the National Aeronautics and Space Administration (NASA) on the Space Shuttle require equipment for accurate determination of weight, or mass. Standard weighing equipment requires a gravity field for operation, so equipment designed to provide an accurate weighing capability in a near zero gravity environment had to be developed to fulfill NASA’s requirements. The small mass measurement instrument (SMMI) was developed by Southwest Research Institute (SWRI) for NASA to fill this need. It can be used to measure small animals, biological samples, and other items. The SMMI is included in the life sciences laboratory equipment (LSLE), which will support life sciences payloads and experiments on Spacelab.
The SMMI is based upon technology developed earlier for the Skylab missions. The SMMI has characteristics of a simple oscillating spring-mass system for which the period of oscillation is a function of the mass of the system. The inertial characteristics of mass are used to measure that mass. Significant work was performed to greatly expand the specimen range, improve the stability and repeatability, and increase the accuracy for this model of the SMMI. The semiautomatic instrument has the capacity to measure specimens from less than 0.002 pound (one gram) to over 22 pounds (10,000 grams) with an accuracy on the order of ~0.05 per cent. The SMMI has a key board, liquid crystal display, and microprocessor, which provide capabilities for entering and deleting data, display of messages or prompts and specimen weight values, memory, and self-calibration features. The SMMI has been tested, certified, and accepted by NASA and is scheduled for use beginning with Spacelab 4.