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DEPLOYABLE ANTENNAS SPACE PROPULSION SPACE STRUCTURES MISSILE DEFENSE TARGETS

The technology L.Garde offers for space structures include the rigidizable telescopic boom, rigidizable space truss structures, high accuracy inflatable parabolic membrane antennas and solar concentrators. L.Garde has patented the telescopic boom technology and currently using this technology for the NASA Solar Sail Technology Demonstration Mission. The solar sail support booms use L.Garde’s Sub-Tg rigidizable composite material. The 14 m diameter inflatable antenna for NASA’s Inflatable Antenna Experiment (IAE) program was designed and built by L.Garde. It flew off the Space Shuttle Endeavour STS-77 mission in May 1996. The other space structures that use the L.Garde rigidizable technology are (a) the ISAT (Innovative Space-Based Radar Antenna Technology) truss of DARPA, (b) support booms of the inflatably-deployed rectangular membrane waveguide, (c) 25m long antenna of the DSX (demonstration and science experiments), (d) Cibola flight experiment antennas, (e) space solar power truss, and many others. The main advantage of using rigidizable materials is their low mass and low stowed (conformable) volume.

The ITSAT was a program originally funded by DARPA in the early 1990s. Its objective was to design and building a lightweight, low stowed volume, high power density solar array panel. The program was in two phases and culminated in the build of the 2.94 kg, 112W ITSAT solar panel. The solar panel was only partially populated with live cells due to budget constraints. The cells used were crystalline Si cells from Ammonix and were mounted on a Kapton substrate. The array was z-folded along the array length to a stowed volume of only 1.11m x 20cm x 10cm. The support structure consisted of a pair of rigidizable aluminum laminate booms on either side of the panel. These booms rigidize by inflation slightly above the aluminum yield point, after which inflatant is no longer needed.

With today’s high efficiency photovoltaic technology, the areal power density can be increased four-fold to about 400 W/m². The specific power can be increased to 140 W/kg. The array panel shown was flight qualified: it was vibration tested at 12 g’s in all axes and thermal cycled between -85 and 70C. It was deployed in a space chamber at -90C.

A lightweight, low stowed-volume deployable-retractable cylindrical structure was designed and fabricated in support of a number of L.Garde projects. The cylindrical object could be repeatedly deployed and retracted for the purpose of providing low-cost methods to calibrate the US Space Situational Awareness (SSA) sensors was further investigated in Phase II. The ultimate goal is to enhance US SOSI systems to enable the US to maintain its abilities to execute space control missions. It will ensure freedom of action in space and support defensive space control through detection, characterization, and identification an attack as well as identification of the attacker and their capabilities.

Phase II resulted in a conceptual objective system design that was enabled by thermally stable, high strain elastomeric composite material developed through sub-scale prototype development and testing. The majority of the Phase II effort focused on identifying methods to enable the mechanical sub-system and demonstrating that the selected method can achieve the system specifications. A system and configuration that could accomplish the goals of the project were identified and demonstrated through sub-scale prototypes. This design was successfully scaled upward to 1 m diameter prototypes which was the limit of available fabrication equipment and facilities. The key to the project was the thermally stable, high strain elastomeric composite material which enabled the design concept.

Several 1 m diameter prototypes were fabricated and were tested to demonstrate the feasibility of the mechanical concept. MORE >