Tech Briefs

Low-Cost, High-Performance MMOD Shielding

Relatively inexpensive fiberglass fabric is proposed in place of costlier materials.

Lyndon B. Johnson Space Center, Houston, Texas

High-performance micro-meteoroid and orbital debris (MMOD) shielding can be constructed from low-cost, off-the-shelf materials. The advantage in using this innovation is in achieving considerable reduction in both cost and mass of the shielding necessary to protect spacecraft from hypervelocity MMOD particle impacts. For instance, in a typical application of this technology for a visiting vehicle used to transport cargo to the International Space Station (ISS) over ten years, an estimated $330,000 is saved (at the time of this reporting) in using a less-expensive MMOD fabric over conventional materials, and an estimated 2,000-kg mass is reduced from the MMOD shielding using the materials and techniques described here compared to conventional means.

Micro-meteoroid and orbital debris shields typically contain relatively expensive ceramic fabrics. For instance, the majority of the MMOD shields on the ISS US Laboratory module contain six layers of ceramic cloth. The purposes of the ceramic fabric in MMOD shields are to break up the incoming MMOD particle or hypervelocity projectile, and cause the debris resulting from the break-up to disperse laterally before impacting subsequent layers of the shield. Ceramics have excellent dynamic properties to achieve good projectile breakup, for either high-density orbital debris particles or lower-density meteoroid particles, by creating relatively high shock pressures in the impacting projectile. Analytical evaluation of various potential materials was conducted to determine which material has suitable characteristics for MMOD protection. Based on these evaluations and cost estimates, materials that could provide suitable MMOD protection at lower cost were identified.

Using inexpensive fiberglass fabric in place of the more expensive ceramic cloth is currently used to protect the SpaceX Dragon commercial cargo vehicle from MMOD particles. This innovation will likely be used on future inflatable modules, and is being considered by Orbital Sciences for use on the Cygnus commercial cargo vehicle. Other future spacecraft can also use this technology in their MMOD shields.

This work was done by Eric Christiansen and Dana Lear of Johnson Space Center, and Frankel Lyons and Bruce Davis of Jacobs Technology. MSC-25250-1

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