Nimbus 4 (also called Nimbus D) was a meteorological satellite. It was the fourth in a series of the Nimbus program. The satellite orbited the Earth once every 1 hour and 47 minutes, at an inclination of 80°. Its perigee was 1,092 kilometers (679 mi) and apogee was 1,108 kilometers (688 mi).

Nimbus 4, the fourth in a series of second-generation meteorological research and development satellites, was designed to serve as a stabilized, earth-oriented platform for the testing of advanced meteorological sensor systems, and for collecting meteorological data. The polar-orbiting spacecraft consisted of three major structures: a ring-shaped sensor mount, solar paddles, and the control system housing.

The solar paddles and the control system were connected to the sensor mount by a truss structure, giving the satellite the appearance of an ocean buoy. Nimbus 4 was nearly 3.7 metres (12 ft) tall, 1.45 metres (4.8 ft) in diameter at the base, and about 3 metres (9.8 ft) across with solar paddles extended. The torus-shaped sensor mount, which formed the satellite base, housed the electronics equipment and battery modules. The lower surface of the torus ring provided mounting space for sensors and telemetry antennas. An H-frame structure mounted within the center of the torus provided support for the larger experiments and tape recorders. Mounted on the control system housing, which was on top of the spacecraft, were Sun sensors, horizon scanners, gas nozzles for attitude control, and a command antenna. The use of an advanced attitude-control subsystem permitted the spacecraft's orientation to be controlled to within plus or minus 1 deg for all three axes (pitch, roll, and yaw). There were 9 primary experiments.

The spacecraft performed well until 14 April 1971, when attitude problems started. The experiments operated on a limited time basis after that time until 30 September 1980.

Approximately 1 hr and 41 min after launch, the satellite was ejected from the final stage of the launch vehicle into a near-circular, near-polar orbit. The objectives of the spacecraft were:

(1) To study new techniques for accurate real-time determination of positions on the earth's surface involving a triangulation technique using satellite transponders and ground-based tracking facilities,

(2) To test relay and one-way ranging techniques used by the Defense Navigation Satellite System

(3) To obtain information about ionospheric effects on satellite geodetic surveys. The 18.14-kg satellite was shaped like a rectangular box (0.36 m by 0.30 m by 0.23 m).

Power was supplied by solar cells mounted on the satellite's exterior. The telemetry transmissions were made by flexible metal tape antennas that were wound around the satellite's structure and deployed after orbital injection. The satellite obtained excellent data for a 6-month period (May 1970 to October 1970). Owing to a lack of funding, however, further tracking was discontinued and, as of January 14, 1972, the satellite was orbiting in an operational off mode.