Discoverer 20 was a satellite placed in a near-polar orbit to continue evaluation of the Agena B system, with particular emphasis on the spacecraft's stabilization system in order to overcome instability problems encountered on previous Discoverers and to attempt ejection, deceleration, reentry through the atmosphere, and recovery of an instrument package. The satellite's scientific experiment package of radiation dosimeters, infrared radiometers, and microwave band detectors was identical to that of Discoverer 18 (launched December 7, 1960). Also included were the necessary telemetry and a 300-lb reentry capsule. The capsule was a bowl-shaped configuration 33 in. in diameter and 27 in. deep. A conical afterbody increased the total length to about 40 in. The recovery capsule payload included photographic film packs, nuclear track plates, and biological specimens. In addition to the external lights for optical tracking, the satellite carried a precision tracking experiment. The total package weighed 2450 lb. Recovery of the capsule was not attempted due to a system malfunction, and thus the scientific experiment data obtained were limited.