William H. Kinard

MISSE7: Building a Permanent Environmental Testbed for the International Space Station

The Materials on the International Space Station Experiments (MISSE) provide low‐cost material exposure experiments on the exterior of the International Space Station (ISS). The original concept for a suitcase‐like box bolted to the ISS to passively expose materials to space has grown to include increasingly complex in situ characterization. As the ISS completes construction, the facilities available to MISSE experiments will increase dramatically. MISSE7 is the first MISSE to take advantage of this new infrastructure. In addition to material exposure, MISSE7 will include characterization of single‐event radiation effects on electronics and solar cell performance in LEO. MISSE7 will exploit the ISS Express Logistics Carrier power and data capabilities and will leave behind a MISSE specific infrastructure for future missions.

Meteoroid investigations using the long duration exposure facility

The Long Duration Exposure Facility was recovered in January, 1990, following 5.7 years of continuous exposure in low‐Earth orbit. The gravity‐stabilized (non‐spinning) nature of LDEF permits the spatial resolution of the flux and trajectories of impacting meteoroids and spacecraft debris particulates. We have completed the acquisition of high‐resolution, stereoscopic video imaging of all large impact features on the entire LDEF, and present here the preliminary results of our efforts to analyze these digitized images, and extract critical data. We present results of detailed crater surveys of LDEF frame intercostal members, and find an unusual local variation in the impact frequency. In a discussion of impactor fluxes derived from LDEF results we explore apparent directionalities for impacting particulates which are not accounted for in current models. We also describe current efforts to characterize meteoroid residues recovered from the impact craters, and we have found that a low, but significant, frac...

First spatio-temporal results from the LDEF interplanetary dust experiment

Abstract The LDEF Interplanetary Dust Experiment was unique in providing a time history of impacts of micron-sized particles on six orthogonal faces of the vehicle over a span of nearly a full year. Over 15000 hits were recorded, representing a mix of zodiacal dust, meteor stream grains, orbital debris, perhaps beta-meteoroids, and possibly interstellar matter. Although the total number was higher than predicted, the relative panel activity distribution was near expectations. Detailed deconvolution of the impact record with orbital data is underway, to examine each of these populations. Very preliminary results of the fairly crude “first look” analysis suggest that debris is the major particle component at 500 km. The data show clear evidence of some known meteor streams as sharp, tightly-focused events, unlike their visible counterparts. Some apparent debris events show similar signatures. Data from the leading and trailing edges suggest a detection of beta-meteoroids, but the analysis is not yet conclusive. Absolute fluxes and flux ratios are not yet known, since the detector status analysis is yet incomplete.

Overview of the space environmental effects observed on the retrieved Long Duration Exposure Facility (LDEF).

The Long Duration Exposure Facility (LDEF), which encompassed 57 experiments with more than 10,000 test specimens, spent 69 months in low Earth orbit (LEO) before it was retrieved by the Space Shuttle in January 1990. Hundreds of LDEF investigators, after studying for over two years these retrieved test specimens and the onboard recorded data and systems hardware, have generated a unique first-hand view of the long term synergistic effects that the LEO environment can have on spacecraft. These studies have also contributed significantly toward more accurate models of the LEO radiation, meteoroid, manmade debris and atomic oxygen environments. This paper provides an overview of some of the many LDEF observations and the implications these can have on future spacecraft such as Space Station Freedom.

Results of the LDEF meteoroid and debris special investigation group

Abstract The Long Duration Exposure Facility was recovered in January, 1990, following 5.7 years of continuous exposure in low-Earth orbit. The gravity-stabilized nature of LDEF permits the resolution of the flux and trajectories of impacting meteoroids and spacecraft debris particulates. We have completed the collection of high-resolution, stereoscopic video imaging of all large impact features on the entire LDEF, and present here the preliminary results of our efforts to reduce these digitized images, and extract critical data. Contrary to our prior assumption, we find that impact craters in the T6 Al alloy are not paraboloid in cross section, but rather are better described by a 6th-order polynomial curve. We explore the implications of this discovery. We present results of detailed crater surveys of LDEF frame intercostal members, finding a unusual local variation in the impact frequency. In a discussion of impactor fluxes derived from LDEF results we explore apparent directionalities for impacting particulates which are not accounted for in current models. We briefly describe the special database designed and used by the M&D SIG. Finally, we present a list of recommendations for further LDEF analyses which will be necessary to ensure the safe design of spacecraft.

Shuttle and MIR Special Environmental Effects and Hardware Cleanliness

The Evaluation of Space Environment and Effects on Materials (ESEM) experiments were developed, flown in-space on the STS-85 mission (August 1997), returned to Earth and analysed as one element of a collaboration between the National Space Development Agency (NASDA) of Japan and the National Aeronautics and Space Agency (NASA) of the United States. The primary objectives of the ESEM experiments were to investigate atomic oxygen effects on materials, cosmic dust and man-made debris, and Shuttle-induced contamination. In particular, the change in scattering of light from the 1/4 mil aluminized Kapton film due to atomic oxygen erosion and Shuttle-induced molecular contamination are discussed. The MIR environmental effects payload (MEEP) was attached to the docking module of the MIR space station for 18 months during calendar years 1996 and 1997 (March 1996, STS 76 to October 1997, STS 86). A solar panel array with more than 10 years space exposure was removed from the MIR core module in November 1997 and returned to Earth in January 1998, STS 89. MEEP and the returned solar array are part of the International Space Station (ISS) Risk Mitigation Program. This space flight hardware has been inspected and studied by teams of space environmental effects (SEE) investigators for micrometeoroid and space debris effects, space exposure effects on materials and electrical performance. This paper reports changes in cleanliness of parts of MEEP and the solar array due to the space exposures. Special attention is given to the extensive water soluble residues deposited on some of the flight hardware surfaces. Directionality of deposition and chemistry of these residues are discussed.

MISSE 5 Thin Films Space Exposure Experiment

Abstract The Materials International Space Station Experiment (MISSE) is a set of space exposure experiments using the International Space Station (ISS) as the flight platform. MISSE 5 is a co-operative endeavor by NASA-LaRC, United Stated Naval Academy, Naval Center for Space Technology (NCST), NASA-GRC, NASA-MSFC, Boeing, AZ Technology, MURE, and Team Cooperative. The primary experiment is performance measurement and monitoring of high performance solar cells for U. S. Navy research and development. A secondary experiment is the telemetry of this data to ground stations. A third experiment is the measurement of low-Earth-orbit (LEO) low-Sun-exposure space effects on thin film materials. Thin films can provide extremely efficacious thermal control, designation, and propulsion functions in space to name a few applications. Solar ultraviolet radiation and atomic oxygen are major degradation mechanisms in LEO. This paper is an engineering report of the MISSE 5 thin films 13 months space exposure experiment.

Particle generation by silicone potting compound of returned Mir solar cells

A solar panel with more than ten years space exposure was returned to Earth in January 1998. Methy-phenyl silicone was used for both the adhesive between the coverglasses and silicon wafer, and for the potting compound between individual solar cells. Glass fiber scrim was used for structural integrity of the panel. Atomic oxygen in low-Earth-orbit interacted with the exposed silicone and converted the outermost layer (several microns thick) to oxidized silicon, i.e. SiOx, where x~2. This brittle SiOx served to protect underlying silicone from oxidation, unless the film was removed by some means. There is much evidence of microeruptions within the potting compound and spewing of silicone and SiOx film debris across the solar cell coverglasses. Ten of 409 solar cells of a returned panel have been scanned with a 50x brightfield microscope. This paper presents measurements of millimeter size SiOx particles and, glass fibers on the returned solar cell coverglasses. Erosion of the potting compound is also discussed.