Richard L. Altstatt

Space application requirements for organic avionics

The NASA Marshall Space Flight Center is currently evaluating polymer based components for application in launch vehicle and propulsion system avionics systems. Organic polymers offer great advantages over inorganic corollaries. Unlike inorganics with crystalline structures defining their sensing characteristics, organic polymers can be engineered to provide varying degrees of sensitivity for various parameters including electro-optic response, second harmonic generation, and piezoelectric response. While great advantages in performance can be achieved with organic polymers, survivability in the operational environment is a key aspect for their practical application. The space environment in particular offers challenges that must be considered in the application of polymer based devices. These challenges include: long term thermal stability for long duration missions, extreme thermal cycling, space radiation tolerance, vacuum operation, low power operation, high operational reliability. Requirements for application of polymer based devices in space avionics systems will be presented and discussed in light of current polymer materials.

Genesis Radiation Environment

The Genesis spacecraft launched on 8 August 2001 sampled solar wind environments at L1 from 2001 to 2004. After the Science Capsule door was opened, numerous foils and samples were exposed to the various solar wind environments during periods including slow solar wind from the streamer belts, fast solar wind flows from coronal holes, and coronal mass ejections. The Survey and Examination of Eroded Returned Surfaces (SEERS) program led by NASAs Space Environments and Effects program had initiated access for the space materials community to the remaining Science Capsule hardware after the science samples had been removed for evaluation of materials exposure to the space environment. This presentation will describe the process used to generate a reference radiation Genesis Radiation Environment developed for the SEERS program for use by the materials science community in their analyses of the Genesis hardware.

Materials Interactions with Space Environment: International Space Station - May 2000 to May 2002

The set of materials interactions with the space flight environment that have produced the largest impacts on the verification and acceptance of flight hardware and on flight operations of the International Space Station (ISS) Program during the May 2000 to May 2002 time frame are described in this paper. In-flight data, flight crew observations, and the results of ground-based test and analysis directly supporting programmatic and operational decision-making are reported.

Ion Flux Environments in Interplanetary Space

†‡ § Spacecraft surfaces in interplanetary space facing the Sun are exposed to 0.5 to 10 keV solar wind H + and He ++ ions. Light ions of these energies have been shown to modify material surfaces through a number of processes includi ng sputtering, blistering, and exfoliation. While solar wind is traditionally consider ed a benign radiation environment, current plans for designing space systems with very thin materials and coatings for mission critical components that depend on surface properties i ncluding reflective sunshades, solar sail propulsion systems, and reflective thermal regulati on materials, it is important to consider the potential risks for damage of these systems due to solar wind ions. This paper provides a status report on development of solar wind ion environment models for use in engineering analyses of materials exposed to the interplanetary space environment. Techniques for reconstructing ion environments from solar wind plasma moments and energetic ion flux measurements are described and envi ronment models derived from solar wind data sets are presented. Finally, statistical estimat es of solar wind ion fluence environments are applied to estimates of sputter rates and blister formation for metal coatings as a function of radial distance from the Sun