it's probably pushing on conductive material nearby with an electrostatic force.
You think a Doctorate expert in electrostatics would miss that?
Dr. Buhler’s background confirms that he is indeed one of NASA’s top experts in electrostatics. In addition to overseeing the management of electrostatic discharge (ESD) and ESD safety for the Space Shuttle, the ISS, and Hubble, Dr. Buhler also established NASA’s Electrostatics and Surface Physics Laboratory at Kennedy Space Center.