Whipple shield

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Whipple shield used on NASA's Stardust probe

The Whipple shield or Whipple bumper, invented by Fred Whipple,[1] is a type of hypervelocity impact shield used to protect manned and unmanned spacecraft from collisions with micrometeoroids and orbital debris whose velocities generally range between 3 and 18 kilometres per second (1.9 and 11.2 mi/s).

As opposed to monolithic shielding of early spacecraft, Whipple shields consist of a relatively thin outer bumper placed a certain distance off the wall of the spacecraft. This improves the shielding-to-mass ratio, critical for spaceflight components, but also increases the thickness of the spacecraft walls, which is not ideal for fitting spacecraft into launch vehicle fairings. The advantage of a bumper placed at a standoff over a single thick shield is that the bumper wall can shock the incoming particle and cause it to disintegrate. This spreads out the impulse of the particle over a larger area of the inner wall of the spacecraft.

There are several variations on the simple Whipple shield. Multi-shock shields,[2][3] like the one used on the Stardust spacecraft, use multiple bumpers spaced apart to increase the shield's ability to protect the spacecraft. Whipple shields that have a filling in between the rigid layers of the shield are called stuffed Whipple shields.[4][5] The filling in these shields is usually a high-strength material like Kevlar or Nextel aluminium oxide fiber.[6] The type of shield, the material, thickness and distance between layers are varied to produce a shield with minimal mass that will also minimize the probability of penetration. There are over 100 shield configurations on the International Space Station alone,[7] with higher-risk areas having better shielding.

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References[edit]

  1. ^ Whipple, Fred L. (1947), "Meteorites and Space Travel", Astronomical Journal, 52: 131, Bibcode:1947AJ.....52Q.131W, doi:10.1086/106009 
  2. ^ Cour-Palais, Burton G.; Crews, Jeanne L. (1990), "A Multi-Shock Concept for Spacecraft Shielding", International Journal of Impact Engineering, 10 (1-4): 135–146, doi:10.1016/0734-743X(90)90054-Y 
  3. ^ US 5067388, Crews, Jeanne L. & Burton G. Cour-Palais, "Hypervelocity Impact Shield", issued November 26, 1991 
  4. ^ Christiansen, Eric L.; Crews, Jeanne L.; Williamsen, Joel E.; Robinson, Jennifer H.; Nolen, Angela M. (1995), "Enhanced Meteoroid and Orbital Debris Shielding", International Journal of Impact Engineering, 17 (1-3): 217–228, doi:10.1016/0734-743X(95)99848-L 
  5. ^ US 5610363, Crews, Jeanne L.; Eric L. Christiansen & Jennifer H. Robinson et al., "Enhanced Whipple Shield", issued March 11, 1997 
  6. ^ 3M Nextel Ceramic Fabric Offers Space Age Protection (PDF), 3M Company, retrieved September 4, 2011 
  7. ^ Christiansen, Eric L. (2003), Meteoroid/Debris Shielding (Technical Report), Washington DC: National Aeronautics and Space Administration, p. 13, TP−2003-210788 

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