VALIDATION OF A UNIQUE CONCEPT FOR A LOW-COST, LIGHTWEIGHT SPACE-DEPLOYABLE ANTENNA STRUCTURE

Large space-deployable antennas are needed for a variety of applicatio ns that include mobile communications, radiometry, active microwave se nsing, very-long-baseline interferometry, DoD space-based radar and mi crospacecraft. Investigators in these fields identify the need for str uctures up to tens of meters in size for operation from 1 to 90 GHz, b ased on different aperture configurations. The selection criteria comm on to all of the users are low cost, lightweight, high reliability and good reflector surface precision. Fortunately, a unique class of spac e structures has recently emerged that offers great potential for sati sfying these criteria. They are referred to as inflatable deployable s tructures. A good example of such a concept is under development at L' Garde Inc.Serious interest from the user community will depend on real istic demonstrations of the viability of the concept. This means that large, lightweight, low-cost structures need to be developed and used to demonstrate deployment reliability in realistic service environment s. The technology data base for the L'Garde inflatable concept will ac commodate the development of reflector antenna structures up to 30 m i n diameter. Since the concept utilizes very low inflation pressure to maintain the required geometry on orbit, gravity-induced deflection of the structure precludes any meaningful ground-based demonstrations of functional performance. Therefore this concept has been selected for a NASA In-Space Technology Experiment Program (IN-STEP) space-based ex periment. The objectives of this experiment are to validate and charac terize the mechanical functional performance of a 14-m-diameter inflat able deployable reflector antenna structure in the orbital operational environment. The experiment will be carried by the NASA Spartan space craft, which is launched, deployed and recovered by the STS. The Spart an will provide mounting, attitude control, power and data recording f or the antenna experiment. The antenna concept development will benefi t from both the experiment and supporting technology developments. Res ults of this experiment are expected to verify the feasibility of fabr icating a large space structure for only a few million dollars, demons trate the reliability of deployment, characterize the quality of the r eflector surface and correlate the analytical performance prediction m odels with actual measured characteristics. Technology developments in support of the experiment, to be conducted at NASA Langley Research C enter and the University of Colorado, will include investigation of ne w and advanced flexible materials, as well as system studies to assess the adequacy of this structural concept for specific classes of appli cations and for the development of analytical performance production t ools. These combined results will be used to advance the technology of the concept with respect to improving surface precision and performan ce predictability and accommodating larger size structures with differ ent configurations in different orbits.