English: View of Discovery's payload bay showing the ATLAS-2 pallet on STS-56. During STS-56, the Atmospheric Laboratory for Applications and Science 2 (ATLAS-2) unpressurized spacelab pallet and its experiment equipment was documented in the payload bay (PLB) of Discovery, Orbiter Vehicle (OV) 103. ATLAS-2 equipment and instruments include: the igloo (center foreground, only the top is visible); the inverters and pump package (far right); port conical scan sensor (next to pump package at far right); the millimeter-wave atmospheric sounder (MAS) antenna (dish-shaped device at pallet center); the starboard conical scan sensor (small cylinder at far left); and the atmospheric trace module spectroscopy (ATMOS) (box behind conical sensor at far left). Smaller ATLAS-2 instruments located in the center of the pallet include (left to right): Active Cavity Radiometer Irradiance Monitor (ACRIM or ACR); Solar Constant Instrument (SOLCON); Solar Spectrum Instrument (SOLSPEC); and MAS (large box just below antenna). The Shuttle Pointed Autonomous Research Tool for Astronomy 201 (SPARTAN-201) is missing as it was in the midst of separation from OV-103 when the photo was made. The remote manipulator system (RMS) is deployed from its location on the port sill longeron. The PLB aft bulkhead, the vertical tail, and the orbital maneuvering system (OMS) pods backdropped against the Earth limb complete the scene.