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Beacon 1



The major objective of the Beacon project was to place a 12-foot diameter inflatable sphere in orbit to study atmospheric density at various levels through visual observations. A secondary objective was to place a third stage instrumented payload casing in orbit. The Beacon 1 mission failed when the upper stages and payload separated from the Redstone first stage prior to first stage burnout.

Mission Profile

Beacon 1 launched on 24 October 1958 at 03:21 UT (23 October, 10:21 p.m. EST) from the Atlantic Missile Range in Cape Canaveral, Florida. At 112 seconds after launch, the Beacon payload broke away from the vehicle. Stages 2 and 3 broke off at 149.9 seconds. The payload fell into the Atlantic Ocean 424 seconds after launch. Total flight time for the first stage was 526 seconds.

Spacecraft and Subsystems

The inflatable 3.66 meter (12 ft) diameter sphere was made of laminated mylar polyester film, 1 mil (25 micrometers) thick, coated on both sides with a microthin (0.45 mil, 11 micrometer) aluminum foil and was uninstrumented. Uninflated, it folded into a cylindrical package with a mass of 4.2 kg (9.26 lbs). The package was held in the bottom of the payload casing, a stainless steel cylindrical shell, 18 cm (7 in) in diameter and 112 cm (44 in) long, mounted on top of the 4th stage motor. An ejection piston device with a 15-pound spring on top of the 4th stage motor was designed to push the payload casing away from the motor after burnout. Above the sphere package within the casing was a connecting valve, bellows, a pressurizing nitrogen bottle, and a squib-actuated valve to inflate the sphere. Above this was a 108.03 MHz, 50 mW phase-modulated Microlock beacon transmitter powered by 8 mercury batteries. Mounted in the top of the structure, covered by a blow-off nose cone, was a small 9-N (2 lb) solid-propellant apogee kick motor and timer. Total mass of the overall payload was about 16.3 kg (36 lbs wt)

Launch Vehicle

The four-stage Jupiter-C, first used for re-entry experiments, was adapted for the Beacon 1 launch and renamed Juno 1. The first stage was a Redstone missile A7 (liquid propellant Hydyne: 60% Unsymmetrical dimethylhydrazine and 40% diethylenetriamine; and liquid oxygen) uprated to 370,000 N (83,000 pounds) of thrust, with a long interstage structure replacing the warhead. The second stage was assembled as a circumferential "tub" of 11 scaled-down Sergeant rockets (solid propellant), the third stage was assembled as three scaled-down Sergeant rockets nested in the center of the "tub", and a single modified Sergeant rocket and casing comprising the fourth stage was mounted on top of this. The three upper stages were rotated as a unit by electric motors before and during launch for attitude stabilization. Total height was 20.9 meters (68.6 ft).

Beacon 1 is sometimes mistakenly referred to as "Explorer VI" in older documents.

Alternate Names

  • Beacon

Facts in Brief

Launch Date: 1958-10-24
Launch Vehicle: Jupiter C (Juno I)
Launch Site: Cape Canaveral, United States
Mass: 4.2 kg

Funding Agency

  • NASA-Office of Space Science Applications United States


  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



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