Eugene Fosness

Development and transition of low-shock spacecraft release devices

The Air Force Research Laboratory (AFRL) has been actively developing low-shock, non-pyrotechnic spacecraft release devices to mitigate problems with traditional pyrotechnic devices. Specifically, pyrotechnic devices produce high shock, contamination, and have costly handling requirements due to their hazardous nature. AFRL has provided funding for development and test of several shape memory alloy (SMA) actuated release devices. Another type of device is based on fuse link technology. Through both ground testing and on-orbit performance, these devices have been shown to reduce shock by at least an order of magnitude, while remaining comparable in size and mass to pyrotechnic devices. Flight heritage includes the U.S. Air Force MightySat I Shape Memory Alloy Release Device (SMARD) experiment that successfully fired and tested two SMA devices. The success of the first low-shock devices is expected to pave the way for numerous applications, such as picosats, large spacecraft release, and fairing and stage separation. A discussion of low-shock technology, current projects, and future potential is presented along with on-orbit test results.

DEPLOYMENT AND RELEASE DEVICES EFFORTS AT THE AIR FORCE RESEARCH LABORATORY SPACE VEHICLES DIRECTORATE

Small satellites require a variety of release devices to accomplish mission-related functions such as separation from the launch vehicle, separation from each other, and deployment of instruments. This paper summarizes low-shock non-pyrotechnic separation efforts that are being managed by the Air Force Research Laboratory Space Vehicles Directorate (AFRL/VS). The AFRL/VS has been actively developing low-shock, non-pyrotechnic spacecraft release devices to mitigate problems associated with traditional pyrotechnic release devices. Specifically, pyrotechnic devices produce high shock, create unnecessary contamination, and have costly handling requirements due to their hazardous nature. Small satellites are particularly susceptible to shock related failure because of the close proximity of sensors and instruments to the shock source. Reducing shock-induced loads on the spacecraft dramatically lowers the overall cost of a spacecrafts design, testing, and operation. Lower loads allow spacecraft components, such as solar arrays and other flexible structures, to be made lighter and use less expensive materials. This results in both smaller mass and reduced production costs. The AFRL/VS is sponsoring the development of several innovative technologies that can provide solutions to these problems. The devices are being designed to replace existing separation and deployment systems.

Recent advances in multi-functional structures

The AFRL and its government and industry partners are actively pursuing a variety of technologies that are revolutionizing the design of future spacecraft structures. Multi-Functional Structures (MFS) is a new design paradigm that seeks to integrate the load carrying capability of traditional structures with other spacecraft functions. The result of this integrated approach is the potential for order of magnitude improvements with respect to mass, cost, and volume. This paper provides an overview of three MFS projects: Lightweight Flexible Solar Array, the Advanced Technology Demonstration System, and Lithium Battery Core (LibaCore). Both technical and programmatic issues associated with maturing this technology and providing a vehicle for affected technology transition are presented. Experience has shown that transitioning new technology requires both technical advancement as well as demonstrating benefits that outweigh potential risks. It also requires developing the confidence needed to insert this technology through appropriate ground and flight demonstrations. The primary purpose of this paper is to show how industry and government can partner successfully to achieve these objectives.

Multiple payload adapters; opening the doors to space

In order to increase the number of satellites that can be flown on a small, fixed budget, low-cost multiple payload adapters (MPAs) are needed to take advantage of excess payload capability on launch systems. This paper will discuss the development of several MPAs at the Air Force Research Laboratory-Space Vehicles Directorate (AFRL/VS) in support of current and future Air Force and DOD requirements. The adapters are being designed using state-of-the-art manufacturing processes, launch vibration isolation, and low-shock separation technology that can accommodate multiple satellite configurations. The MPAs can deploy multiple satellites, in a large range of sizes (15 kg to 1000 kg), depending on the design configuration. The MPAs are being developed to support the Minotaur, the Evolved Expendable Launch Vehicle (EELV), as well as the Space Shuttle. The successful development of these adapters will greatly reduce the cost of launching satellites into orbit by allowing for the efficient use of currently unused payload margins.

On-orbit experiments and applications of shape memory alloy mechanisms

Spacecraft require a variety of mechanisms to accomplish mission-related functions such as deployment, articulation, and positioning. Current off-the-shelf devices such as pyrotechnic separation nuts, paraffin actuators, and other electro-mechanical devices may not be able to meet future satellite requirements, such as low shock and vibration, and zero contamination. The Air Force Research Laboratory (AFRL), with corporate and government partners, has developed Shape Memory Alloy (SMA) spacecraft release mechanisms and hinges as alternatives. In order to meet future goals, the SMA devices have been designed to reduce shock and vibration, reduce parts, and eliminate pyrotechnics. This paper will focus on descriptions and results of on-orbit SMA mechanism experiments and applications. AFRL has flown SMA release devices as part of the Shape Memory Alloy Release Device (SMARD) experiment on MightSat I. The SMARD experiment, that compared the shock and release times of two SMA devices with those of current off-the-shelf devices, was conducted in May 1999 with extremely successful results. In addition, four AFRL funded SMA release mechanisms successfully deployed the Air Force Academy FalconSat spacecraft from the Orbital Sub-Orbital Program Space Launch Vehicle in January 00. AFRL has also conducted an on-orbit experiment with SMA hinges. The hinges were flown as part of the Lightweight Flexible Solar Array program, that was a joint AFRL/DARPA/NASA/Lockheed Martin program to develop innovative solar array technologies. Six SMA hinges were launched as part of the LFSA experiment on the Space Shuttle Columbia in July 1999 with successful results.