The Multispectral Scanner (MSS) aboard Landsats 1–5 measured light in four spectral bands: two visible and two near-infrared. Landsats 1, 2, and 3 had an 18-day revisit cycle; Landsats 4 and 5 maintained a 16-day revisit cycle. Data from MSS proved to be superior to the Return Beam Vidicon, which was intended to be the prime instrument of the early Landsats.