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Surveyor 4

NSSDCA/COSPAR ID: 1967-068A

Description

This spacecraft was the fourth in a series designed to achieve a soft landing on the moon and to return photography of the lunar surface for determining characteristics of the lunar terrain for Apollo lunar landing missions. Equipment on board included a television camera and auxiliary mirrors, a soil mechanics surface sampler, strain gauges on the spacecraft landing legs, and numerous engineering sensors. After a flawless flight to the Moon, radio signals from the spacecraft ceased during the terminal-descent phase at 2:02:40 UT (41 seconds after main retrorocket ignition) on 17 July 1967, approximately 2.5 min before planned touchdown. Contact with the spacecraft was never reestablished, and the mission was unsuccessful. It was not known if only communications were lost and the lander proceeded with a soft landing, or if there were other failures and the lander crashed. The landing target was estimated to be 0.43 N, 1.62 W (or 0.37 N, 1.55 W) for a soft landing and 0.47 N, 1.44 W (or 0.469 N, 1.086 W) for a ballistic crash. It is also possible the spacecraft solid propellant retrorockets exploded, causing destruction of Surveyor 4.

Spacecraft and Subsystems

The basic Surveyor spacecraft structure consisted of a tripod of thin-walled aluminum tubing and interconnecting braces providing mounting surfaces and attachments for the power, communications, propulsion, flight control, and payload systems. A central mast extended about one meter above the apex of the tripod. Three hinged landing legs were attached to the lower corners of the structure. The legs held shock absorbers, crushable, honeycomb aluminum blocks, and the deployment locking mechanism and terminated in footpads with crushable bottoms. The three footpads extended out 4.3 meters from the center of the Surveyor. The spacecraft was about 3 meters tall. The legs folded to fit into a nose shroud for launch.

A 0.855 square meter array of 792 solar cells was mounted on a positioner on top of the mast and generated up to 85 Watts of power which was stored in rechargeable silver-zinc batteries. Communications were achieved via a movable large planar array high gain antenna mounted near the top of the central mast to transmit television images, two omnidirectional conical antennas mounted on the ends of folding booms for uplink and downlink, two receivers and two transmitters. Thermal control was achieved by a combination of white paint, high IR-emittance thermal finish, polished aluminum underside. Two thermally controlled compartments, equipped with superinsulating blankets, conductive heat paths, thermal switches and small electric heaters, were mounted on the spacecraft structure. One compartment, held at 5 - 50 degrees C, housed communications and power supply electronics. The other, held between -20 and 50 degrees C, housed the command and signal processing components. The TV survey camera was mounted near the top of the tripod and strain gauges, temperature sensors, and other engineering instruments are incorporated throughout the spacecraft. One photometric targets was mounted near the end of a landing leg and one on a short boom extending from the bottom of the structure. Other payload packages, which differed from mission to mission, were mounted on various parts of the structure depending on their function.

A Sun sensor, Canopus tracker and rate gyros on three axes provided attitude knowledge. Propulsion and attitude control were provided by cold-gas (nitrogen) attitude control jets during cruise phases, three throttlable vernier rocket engines during powered phases, including the landing, and the solid-propellant retrorocket engine during terminal descent. The retrorocket was a spherical steel case mounted in the bottom center of the spacecraft. The vernier engines used monomethyl hydrazine hydrate fuel and MON-10 (90% N2O2, 10% NO) oxidizer. Each thrust chamber could produce 130 N to 460 N of thrust on command, one engine could swivel for roll control. The fuel was stored in spherical tanks mounted to the tripod structure. For the landing sequence, an altitude marking radar initiated the firing of the main retrorocket for primary braking. After firing was complete, the retrorocket and radar were jettisoned and the doppler and altimeter radars were activated. These provided information to the autopilot which controlled the vernier propulsion system to touchdown.

The Surveyor program involved building and launching seven Surveyor spacecraft to the Moon at a total cost of $469 million.

Alternate Names

  • 02875
  • Surveyor4

Facts in Brief

Launch Date: 1967-07-14
Launch Vehicle: Atlas-Centaur
Launch Site: Cape Canaveral, United States
Mass: 283 kg

Funding Agency

  • NASA-Office of Space Science Applications (United States)

Discipline

  • Planetary Science

Additional Information

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

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Leonard D. JaffeProject ScientistNASA Jet Propulsion Laboratory

Selected References

  • Surveyor 4 mission report, JPL, Calif. Inst. Technol., TR 32-1210, Pasadena, CA, Jan. 1968.
Surveyor

Surveyor at National Air and Space Museum

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