Aldrin relied on a felt-tip marker, since the non-conductive tip would close the contact without shorting it out, or causing a spark.
奥尔德林当时使用的是毡制粗头笔，它的尖头是不导电的，接触开关不会造成短路或引发火花。
2
KDP (Potassium Dihydrogen Phosphate, it is shorting KH2PO4) crystal is a non-linear optical material used for laser frequency conversion and electrooptic modulators.