Mission Specialist (MS) Peter J.K. Wisoff (bottom), wearing an Extravehicular Mobility Unit (EMU), works with the antenna on the European Retrievable Carrier (EURECA) while Payload Commander (PLC) G. David Low, on the Remote Manipulator System (RMS) robot arm, hovers above. The two astronauts were conducting Detailed Test Objective (DTO) procedures in the payload bay of Endeavour. Low, also suited in an EMU, is anchored to the RMS via a Portable Foot Festraint (PFR) Manipulator Foot Restraint (MFR). DTO results will assist in refining several procedures being developed to service the Hubble Space Telescope (HST) on mission STS-61 in December 1993. Visible in Endeavour's payload bay (PLB) are the open Spacelab (SL) tunnel adapter hatch (foreground), SPACEHAB-01 (Commercial Middeck Augmentation Module (CMAM) (foreground), and the top of the Superfluid Helium On Orbit Transfer (SHOOT) payload. The astronauts and Endeavour's vertical stabilizer and Orbital Maneuvering System (OMS) pods are backdropped against the blackness of space.