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Gemini 5

NSSDCA/COSPAR ID: 1965-068A

Description

Gemini 5, carrying astronauts Gordon Cooper and Charles "Pete" Conrad was the third crewed Earth-orbiting spacecraft of the Gemini series. The flight was designed to last eight days and test rendezvous procedures. The major objectives of this mission were to demonstrate a long-duration crewed flight, evaluate the effects of long periods of weightlessness on the crew, and test rendezvous capabilities and maneuvers using a rendezvous evaluation pod. Secondary objectives included demonstration of all phases of guidance and control systems to support rendezvous and controlled reentry guidance, to evaluate the fuel cell power system and rendezvous radar, to test the capability of either pilot to maneuver the spacecraft in orbit to close proximity with another object, and to conduct 17 experiments.

Mission Profile

Gemini 5 was launched from Complex 19 on 21 August 1965 at 8:59:59 a.m. EST (13:59:59.518 UT) and inserted into a 162.0 x 350.1 km Earth orbit at 9:05:55. The rendezvous evaluation pod (REP), a 34.5 kg optical and electronic duplicate of the Agena planned for use in later Gemini rendezvous missions was deployed two hours into the flight on the second revolution. About 36 minutes into the evaluation of the rendezvous system, the crew noticed the pressure in the oxygen supply tank of the fuel cell system was dropping. At some point earlier in the flight the oxygen supply heater element had failed, and the pressure dropped from nominal pressure of 850 psia to a low of 65 psia 4 hours and 22 minutes into the flight. This was still above the 22.2 psia minimum but it was decided to cancel the REP exercise and power the spacecraft down. An analysis was carried out on the ground and a powering up procedure was started on the seventh revolution. Over the rest of the mission the pressure slowly rose in the fuel cells and sufficient power was available at all times.

Four rendezvous radar tests were conducted during the mission, starting on revolution 14 on the second day. On the third day a simulated rendezvous with a phantom Agena was conducted. On day five thruster number 7 became inoperative and maneuvering system operation became sluggish. Thruster number 8 failed the next day and the system became increasingly erratic. Limited experimental and operational activities continued throughout the remainder of the mission. Retrofire was made on revolution 120 (one revolution early due to a threatening tropical storm near the landing area) at 7:27:42 a.m. EST on August 29. Splashdown occurred at 7:55:13 in the western Atlantic at 29.73 N, 69.75 W after a total mission time of 190:55:14. Splashdown was 169 km short of the target due to a ground-based computer program error. The crew arrived onboard the aircraft carrier U.S.S. Lake Champlain at 9:26 and the spacecraft was recovered at 11:50.

All objectives were achieved except rendezvous with the REP and pilot tests associated with the rendezvous and the demonstration of controlled reentry to a predetermined landing point. Scientific studies included zodiacal light, synoptic terrain, synoptic weather photography, and a cloudtop spectrometer experiment. In addition, five medical and seven technological experiments were performed during the mission. One photography experiment was cancelled because of cancellation of the rendezvous maneuver. The mission demonstrated human ability to adapt to weightlessness over an extended period and then readapt to normal gravity and was considered successful.

Spacecraft and Subsystems

The Gemini spacecraft was a cone-shaped capsule consisting of two components, a reentry module and an adaptor module. The adaptor module made up the base of the spacecraft. It was a truncated cone 228.6 cm high, 304.8 cm in diameter at the base and 228.6 cm at the upper end where it attached to the base of the reentry module. The re-entry module consisted of a truncated cone which decreased in diameter from 228.6 cm at the base to 98.2 cm, topped by a short cylinder of the same diameter and then another truncated cone decreasing to a diameter of 74.6 cm at the flat top. The reentry module was 345.0 cm high, giving a total height of 573.6 cm for the Gemini spacecraft.

The adaptor module was an externally skinned, stringer framed structure, with magnesium stringers and an aluminum alloy frame. The adaptor was composed of two parts, an equipment section at the base and a retrorocket section at the top. The equipment section held fuel and propulsion systems and was isolated from the retrorocket section by a fiber-glass sandwich honeycomb blast shield. The retrorocket section held the re-entry rockets for the capsule.

The reentry module consisted mainly of the pressurized cabin which held the two Gemini astronauts. Separating the reentry module from the retrorocket section of the adaptor at its base was a curved silicone elastomer ablative heat shield. The module was composed predominantly of titanium and nickle-alloy with beryllium shingles. At the narrow top of the module was the cylindrical reentry control system section and above this the rendezvous and recovery section which holds the reentry parachutes. The cabin held two seats equipped with emergency ejection devices, instrument panels, life support equipment, and equipment stowage compartments in a total pressurized volume of about 2.25 cubic meters. Two large hatches with small windows could be opened outward, one positioned above each seat.

Control, Propulsion, and Power

Attitude control was effected by two translation-maneuver hand controllers, an attitude controller, redundant horizon sensor sytems, and reentry control electronics, with guidance provided via an inertial measuring unit and radar system. The orbital attitude and maneuver system used a hypergolic propellant combination of monomethylhydrazine and nitrogen tetroxide supplied to the engines by a helium system pressurized at 2800 psi. Two 95 lb translation thrusters and eight 23 lb attitude thrusters were mounted along the bottom rim of the adaptor, and two 79 lb and 4 95 lb thrusters were mounted at the front of the adaptor. Power was supplied by a fuel cell power system to a 22- to 30-volt DC two-wire system. During reentry and post-landing power was supplied by four 45 amp-hr silver-zinc batteries.

Communications

Voice communications were performed at 296.9 MHz with an output power of 3 W. A backup transmitter-receiver at 15.016 MHz with an output power of 5 W was also available. Two antenna systems consisting of quarter-wave monopoles were used. Telemetry was transmitted via three systems, one for real time telemetry, one for recorder playback, and a spare. Each system was frequency-modulated with a minimum power of 2 W. Spacecraft tracking consisted of two C-band radar transponders and an acquisition-aid beacon. One transponder is mounted in the adaptor with a peak power output of 600 W to a slot antenna on the bottom of the adaptor. The other is in the reentry section, delivering 1000 W to three helical antennas mounted at 120 degree intervals just forward of the hatches. The acquisition-aid beacon was mounted on the adaptor and had a power of 250 mW.

Reentry

At the time of reentry, the spacecraft would be maneuvered to the appropriate orientation and equipment adaptor section would be detached and jettisoned, exposing the retrorocket module. The retrorockets consisted of four spherical-case polysulfide ammonium perchlorate solid-propellant motors mounted near the center of the reentry adaptor module, each with 11,070 N thrust. They would fire to initiate the spacecraft reentry into the atmosphere, with attitude being maintained by a reentry control system of 16 engines, each with 5.2 N thrust. The retrorocket module would then be jettisonned, exposing the heat shield at the base of the reentry module. Along with the ablative heat shield, thermal protection during reentry was provided by thin Rene 41 radiative shingles at the base of the module and beryllium shingles at the top. Beneath the shingles was a layer of MIN-K insulation and thermoflex blankets. At an altitude of roughly 15,000 meters the astronauts would deploy a 2.4 meter drogue chute from the rendezvous and recovery section. At 3230 meters altitude the crew releases the drogue which extracts the 5.5 meter pilot parachute. The rendezvous and recovery section is released 2.5 seconds later, deploying the 25.6 meter main ring-sail parachute which is stored in the bottom of the section. The spacecraft is then rotated from a nose-up to a 35 degree angle for water landing. At this point a recovery beacon is activated, transmitting via an HF whip antenna mounted near the front of the reentry module.

Gemini Program

The Gemini program was designed as a bridge between the Mercury and Apollo programs, primarily to test equipment and mission procedures in Earth orbit and to train astronauts and ground crews for future Apollo missions. The general objectives of the program included: long duration flights in excess of of the requirements of a lunar landing mission; rendezvous and docking of two vehicles in Earth orbit; the development of operational proficiency of both flight and ground crews; the conduct of experiments in space; extravehicular operations; active control of reentry flight path to achieve a precise landing point; and onboard orbital navigation. Each Gemini mission carried two astronauts into Earth orbit for periods ranging from 5 hours to 14 days. The program consisted of 10 crewed launches, 2 uncrewed launches, and 7 target vehicles, at a total cost of approximately 1,280 million dollars.

Alternate Names

  • 01516

Facts in Brief

Launch Date: 1965-08-21
Launch Vehicle: Titan II
Launch Site: Cape Canaveral, United States
Mass: 3605.0 kg

Funding Agency

  • NASA-Office of Manned Space Flight (United States)

Disciplines

  • Astronomy
  • Earth Science
  • Human Crew
  • Space Physics

Additional Information

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

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. William C. SchneiderProject ManagerNASA Headquarters 
Dr. Charles W. MathewsProject ManagerNASA Headquarters 
Dr. George E. MuellerProgram ManagerNASA Headquartersinfo@kistleraero.com

Selected References

Gemini midprogram conference including experimental results, NASA, SP-121, 1966. (Papers Presented at the Manned Spaceflight Center, Houston, Feb. 23-25, 1966)

Gemini summary conference, NASA, SP-138, Wash, DC, Feb. 1967.

Gemini 5 sustains accelerated U.S. pace, Space Technol. International, 8, No. 4, 4-12, Oct. 1965.

Grimwood, J. M., et al., Project Gemini technology and operations - A chronology, NASA, NASA SP-4002, Wash., DC, 1969.

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