News articles keep referring to the James Webb Space Telescope's sunshield as "about the size of a tennis court", which raises the question: could it function as a tennis court? Or, more specifically, if you threw a tennis ball at it, would the tennis ball bounce off the sunshield elastically, or would it tear through the sunshield fabric, or would something else happen?

(extra credit question: Is the answer time-dependent? e.g. perhaps the sunshield is nice and strong and elastic now, but will grow weaker or more brittle over time, due to radiation damage?)

  • $\begingroup$ Long time ago since I read it, but yes, the sunshield is expected to fail over time - think of long term sun exposure damaging your skin. $\endgroup$ Jan 25, 2022 at 1:05

1 Answer 1


Answer: Yes

The first (sunward) layer of the sunshield is .002" thick Kapton. According to Dupont (the manufacturer) the yield strength is 10,000psi https://www.matweb.com/search/datasheet_print.aspx?matguid=46461ce29078477daf39c20f499e0bc8 . So you could use it for a tennis court ... or a trampoline.

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    $\begingroup$ The relevant parameters here are not just the yield strength but the tension over which it is spread out and the rigidity of the frame over which it is stretched. Put another way the yield strength doesn't tell you whether the kapton would simply crumple and envelope the tennis ball like a bag. $\endgroup$
    – Puffin
    Oct 29, 2022 at 12:14

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