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Crews, Jeanne Lee

Publications and source records attributed to Crews, Jeanne Lee.

Flexible Shields for Protecting Spacecraft Against Debris

A report presents the concept of Flexshield a class of versatile, lightweight, flexible shields for protecting spacecraft against impacts by small meteors and orbiting debris. The Flexshield concept incorporates elements of, but goes beyond, prior spacecraft-shielding concepts, including those of Whipple shields and, more recently, multi-shock shields and multi-shock blankets. A shield of the Flexshield type includes multiple outer layers (called bumpers in the art) made, variously, of advanced ceramic and/or polymeric fibers spaced apart from each other by a lightweight foam. As in prior such shields, the bumpers serve to shock an impinging hypervelocity particle, causing it to disintegrate vaporize, and spread out over a larger area so that it can be stopped by an innermost layer (back sheet). The flexibility of the fabric layers and compressibility of the foam make it possible to compress and fold the shield for transport, then deploy the shield for use. The shield can be attached to a spacecraft by use of snaps, hook-and-pile patches, or other devices. The shield can also contain multilayer insulation material, so that it provides some thermal protection in addition to mechanical protection.

Christiansen, Eric L.

Hypervelocity impact shield

A hypervelocity impact shield and method for protecting a wall structure, such as a spacecraft wall, from impact with particles of debris having densities of about 2.7 g/cu cm and impact velocities up to 16 km/s are disclosed. The shield comprises a stack of ultra thin sheets of impactor disrupting material supported and arranged by support means in spaced relationship to one another and mounted to cover the wall in a position for intercepting the particles. The sheets are of a number and spacing such that the impacting particle and the resulting particulates of the impacting particle and sheet material are successively impact-shocked to a thermal state of total melt and/or vaporization to a degree as precludes perforation of the wall. The ratio of individual sheet thickness to the theoretical diameter of particles of debris which may be of spherical form is in the range of 0.03 to 0.05. The spacing between adjacent sheets is such that the debris cloud plume of liquid and vapor resulting from an impacting particle penetrating a sheet does not puncture the next adjacent sheet prior to the arrival thereat of fragment particulates of sheet material and the debris particle produced by a previous impact.

Cour-Palais, Burton G.

Augmentation of orbital debris shielding for Space Station Freedom

Augmentation concepts for the Space Station Freedom (SSF) are described in detail and advantages and disadvantages of various proposals are evaluated. It is pointed out that early augmentation of SSF debris shielding, which would take place 6-9 years after the First Element Launch, could provide the greatest advantages to the program in terms of weight, cost, and safety benefits. Potential augmentation concepts include an attached, rigid aluminum second bumper; the multi-shock shield concept; a mesh double bumper concept; a debris shield augmentation element; a multi-shock airbag protection concept for 2-10 cm debris; and a debris sweeper. Requirements for and operation and deployment of these concepts are described in detail and an example of the augmentation effect on cumulative SSF probability of no-failure from debris and meteoroid impacts is given. An estimate of predicted encounter rates between debris and a 100 m radius sphere around SSF is presented.

Christiansen, Eric L.

Hypervelocity impact studies using a rotating mirror framing laser shadowgraph camera

The need to study the effects of the impact of micrometeorites and orbital debris on various space-based systems has brought together the technologies of several companies and individuals in order to provide a successful instrumentation package. A light gas gun was employed to accelerate small projectiles to speeds in excess of 7 km/sec. Their impact on various targets is being studied with the help of a specially designed continuous-access rotating-mirror framing camera. The camera provides 80 frames of data at up to 1 x 10 to the 6th frames/sec with exposure times of 20 nsec.

Parker, Vance C.