The Humidity Sounder for Brazil (HSB) was an instrument launched on NASA's Earth Observing System satellite Aqua launched in May 2002. It was a four-channel passive microwave radiometer, with one channel at 150 GHz and three channels at 183 GHz. It was very similar in design to the AMSU-B instrument, except it lacked the 89 GHz surface sounding channel. It was intended to study profiles of atmospheric water vapor and provide improved input data to the cloud-clearing algorithms in the Unified AIRS Retrieval Suite, but the scan mirror motor failed on February 5, 2003. It worked with the Atmospheric Infrared Sounder and AMSU-A to form the AIRS Sounding Suite.