In a meeting, Dr. Wernher von Braun, Frederick C. Durant III, Alexander Satin, David Young, Dr. Fred L. Whipple, Dr. S. Fred Singer, and Commander George W. Hoover agreed that a Redstone rocket with a Loki cluster as the second stage could launch a satellite into a 200-mile orbit without major new developments. This became a joint Army-Navy study project after meeting at Redstone Arsenal on August 3. Project Orbiter was a later outgrowth of this proposal and resulted in the launching of Explorer I on January 31, 1958.

Research and development Policy Council (DOD) unanimously recommended that the time-risk factor in the scientific satellite program be brought to the attention of the Secretary of the Defense for determination as to whether a Redstone backup program was indicated.

Secretary of Defense Neil McElroy directed the Army to proceed with the launching of the Explorer earth satellites. This order, in effect, resumed the Orbiter project that had been eliminated from the IGY satellite planning program on September 9, 1955. Von Braun was to modify two Jupiter-C missiles (modified Redstones) and attempt to place an artificial earth satellite in orbit by March 58.

Explorer I, the first U.S. earth satellite, was launched by a modified Army Ballistic Missile Agency Jupiter-C. Explorer I, developed by the Jet Propulsion Laboratory, carried the U.S.-IGY (International Geophysical Year) experiment of James A. Van Allen and resulted in the discovery of the radiation belt around the earth.

In its first NASA use from Vandenberg AFB a Scout rocket (#122) was successfully launched. The 18-pound Explorer 19 atmosphere density satellite was successfully injected into orbit. 12 foot dia. balloon; identical to Explorer 9; atmospheric density studies. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

The primary objective of GEOS-A was to provide global geodetic measurements for determining the positions of fiducial control points on the Earth to an accuracy of 10 meters in an Earth centre of mass co-ordinate system, and to determine the structure of the Earth's gravity field to 5 parts in 10 million. Instrumentation included (1) four optical beacons, (2) laser reflectors, (3) a radio range transponder, (4) Doppler beacons, and (5) a range and range rate transponder. These were designed to operate simultaneously to fulfil the objectives of locating observation points (geodetic control stations) in a three dimensional earth centre-of-mass co-ordinate system within 10 m of accuracy, of defining the structure of the earth's irregular gravitational field and refining the locations and magnitudes of the large gravity anomalies, and of comparing results of the various systems onboard the spacecraft to determine the most accurate and reliable system. In January 1967, a failure in the satellite's command system rendered several geodetic systems inoperable. Radio doppler measurements and the passive laser reflector experiment could continue indefinitely, however. Additional Details: here....

Ionospheric research; data correlated with Alouette 2. The Explorer 31, Direct Measurement Explorer, was launched with a Canadian Alouette II on November 28, 1965, on a Thor-Agena rocket from Vandenberg Air Force Base, California. The double-launch project, known as ISIS-X was the first in a new co-operative NASA-Canadian Defense Research Board program for International Satellites for Ionospheric Studies. Explorer 31 was in orbit with an apogee just over a kilometre more than Alouette's and with a perigee of just more than a kilometre lower. The orbits were some 3000 km at apogee and 500 km at perigee. Eight ionospheric measurement experiments sampled the environment both forward and after the satellite's path.

Earth magnetic tail measurements. Lunar Orbit (Selenocentric). The Westinghouse Aerospace Division, under contract to National Aeronautics and Space Administration's Goddard Space Flight Center, engaged in the system design, integration, assembly and launch support for Anchored Interplanetary Monitoring Platform Satellite, officially designated Explorer 35 by the National Aeronautics and Space Administration. It was launched on July 19, 1967, with the primary objectives of investigation of interplanetary plasma and the interplanetary magnetic field out to and at the lunar distance, in either a captured lunar orbit or a geocentric orbit of the earth. In the geocentric orbit, the apogee was near or beyond the lunar distance. In a lunar orbit, additional objectives included obtaining data on dust distribution, lunar gravitational field, ionosphere, magnetic field, and radiation environment around the moon. AIMP-E also studied spatial and temporal relationships of geophysical and interplanetary phenomena simultaneously being studied by several other National Aeronautics and Space Administration satellites. The investigation in the vicinity of the moon provided for measurements of the characteristics of the interplanetary dust distribution, solar and galactic cosmic rays, as well as a study of the magnetohydrodynamic wake of the earth in the interplanetary medium at the lunar distances.

The geodetic instrumentation systems included (1) four optical beacons, (2) two C-band radar transponders, (3) a passive radar reflector, (4) a sequential collation of range radio range transponder, (5) a Goddard range and range rate transponder, (6) laser reflectors, and (7) Doppler beacons. Non-geodetic systems included a laser detector and a Minitrack interferometer beacon. The objectives of the spacecraft were to optimise optical station visibility periods and to provide complementary data for inclination-dependent terms established by the Explorer 29 (GEOS 1) gravimetric studies. The spacecraft was placed into a retrograde orbit to accomplish these objectives. Operational problems occurred in the main power system, optical beacon flash system, and the spacecraft clock, and adjustments in scheduling resulted in nominal operations.

In its first use at Cape Canaveral, a NASA Long Tank Thrust Augmented Thor/ Delta boosted Explorer 43 into orbit. This was the first "Super Six" configuration Thor/Delta, with strap-on solid-rocket boosters motors, to be launched from the Eastern Test Range. Earth magnetosphere research. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).