The DAPS is only capable of moving in the weightless environment on orbit, not in Earth’s gravity on the ground. DAPS therefore was tested on a platform structure with wheels and bearings.
The test includes motions responsible for tracking and slewing between neutron star targets in the sky with NICER's X-ray Timing Instrument, which is stationary during this test because it is too heavy to be moved by the DAPS motors in Earth's gravity.