Explorer 32, also known as Atmosphere Explorer-B (AE-B), was a NASA satellite launched by the United States to study the Earth's upper atmosphere. It was launched from Cape Canaveral on a Delta C1 launch vehicle, on 25 May 1966. It was the second of five "Atmosphere Explorer", the first being Explorer 17. Though it was placed in a higher-than-expected orbit by a malfunctioning second stage on its launch vehicle, Explorer 32 returned data for ten months before failing due to a sudden depressurization. The satellite reentered the Earth's atmosphere on 22 February 1985.

The Explorer program is a NASA exploration program that provides flight opportunities for physics, geophysics, heliophysics, and astrophysics investigations from space. Launched in 1958, Explorer 1 was the first spacecraft of the United States to achieve orbit. Over 90 space missions have been launched since. Starting with Explorer 6, it has been operated by NASA, with regular collaboration with a variety of other institutions, including many international partners.

Launchers for the Explorer program have included Juno I, Juno II, various Thor, Scout, Delta and Pegasus launch vehicles, and Falcon 9.

Currently, the program has three classes: Medium-Class Explorers (MIDEX), Small Explorers (SMEX), and University-Class Explorers (UNEX), with select Missions of Opportunity operated with other agencies.