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Shielding of robots in space

  1. Oct 29, 2005 #1
    1. how does NASA protect its robots in space(eg satellites, space stations etc) from solar radiation ???????????????????
    ( their processors, chips etc )
    I've checked lot of sites for it but none of them mentioned about their shielding. does this mean that radiation have negligible effects on robots??

    2. how does radiation affect metals in space?
    i've heard that metals become brittle. is it true???
    If yes then by what rate?? how to protect them them??

    somebody PLEASE HELP!!!!!!!!!!!!!!!!!!!!!!:bugeye:
     
  2. jcsd
  3. Oct 29, 2005 #2
    This might help. http://www.northerndiecast.com/emi.htm
    http://www.eas.asu.edu/~holbert/eee460/spacerad.html

    http://lsda.jsc.nasa.gov/books/apollo/S2ch3.htm

    Electronics can be shielded from electromagnetic waves with the help of metals because of metals' conductivity.

    Also since a lot of the satellites are near Earth, the solar radiation dose is highly reduced in comparision to open space. The rest is absorbed through appopriate shielding.

    Magnetic shielding is an option but as of now, still untested. We have little experience with superconducting electromagnets in open space.

    I should also note that even with high shielding, a person in say Apollo 11 would experience much more radiation than a person on Earth. However because he doesn't have to stay in space forever, the net radiation dose will cause little harm. The same applies to electronics. An exposure to space without shielding would likely have little effect on electronics. A prolonged exposure would likely spoil them.
     
    Last edited: Oct 29, 2005
  4. Oct 29, 2005 #3

    Astronuc

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    Staff: Mentor

    Basically, NASA and military use radiation hardened microchips which are specially designed to operate in radiation fields. Shielding involves a trade off with mass. Basically one can use the satellite structure as shielding. Radiation affects the microelectronics more signficantly than the structural materials.

    Space Radiation Effects on Integrated Circuits - http://parts.jpl.nasa.gov/asic/Appendix.3.html

    Design for Radiation Tolerance - http://parts.jpl.nasa.gov/asic/Sect.3.4.html#rad.hard.1

    The RAD750 microprocessor is specifically developed for radiation environment - see http://en.wikipedia.org/wiki/RAD750

    http://www.baesystems.com/newsroom/2002/feb/040202news1.htm

    In space, high energy particles ionize the atoms and knock them out of equilibrium position in the crystal lattice - and this is the same problem in nuclear reactors. The knocking of atoms produces higher levels of dislocations in the structure, which becomes somewhat stronger, but also more brittle. One simply designs the structure with this in mind.

    The embrittelment of a metal tends to saturate with dose (integral of dose rate with respect to time), i.e. the dislocation density essentially saturates. We now have correlations of material properties, e.g. hardness and strength, with respect to dose - or displacements per atom (dpa).
     
  5. Oct 29, 2005 #4

    Danger

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    Gold Member

    I've also seen something about 'vacuum lock' of metal machinery. I believe that it has to do with van der Waals forces siezing parts up when there's no air between them. Special very broad temperature-range lubricants are required. Can you elaborate, Astro?
     
  6. Nov 1, 2005 #5

    Astronuc

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    Staff: Mentor

    I know that was an issue back in the days of Mercury, Gemini, Apollo and Skylab - before ISS. I don't know how big an issue it is these days.

    I believe is related to simple atomic (primarily surface) diffusion between surfaces in contact, especially warm or heated surfaces.

    I searched for a good discussion or paper of the phenomenon, but couldn't find one. You're right Danger, there are special lubricants for vacuum and a broad temperature range.
     
  7. Nov 7, 2005 #6
    thanx.
    but for lubricating do we require air as a medium??o:)
     
  8. Nov 7, 2005 #7

    Danger

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    Gold Member

    No. Most lubricants, in fact, preclude air as well as moisture. That's why they also work as metal preservatives.
     
  9. Nov 9, 2005 #8
    Thanx For The Info :-)
     
  10. Nov 10, 2005 #9
    A shameless plug for my research group since we work on radiation shielding of Solar Particle Events, Trapped Radiation (Van Allen radiation) and Galatic Cosmic Rays:
    http://csmb.larc.nasa.gov/csmbexternal/home.htm

    I know- shameless.
     
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