Status: Operational 1967. First Launch: 1967-06-14. Last Launch: 1967-06-14. Number: 1 . Gross mass: 244 kg (537 lb).
Mariner 5 carried a complement of experiments to probe Venus's atmosphere with radio waves, scan its brightness in ultraviolet light, and sample the solar particles and magnetic field fluctuations above the planet.
The spacecraft was fully attitude stabilized, using the sun and Canopus as references. A central computer and sequencer subsystem supplied timing sequences and computing services for other spacecraft subsystems. The octagonal bus structure had four solar panels and was 3-axis stabilized using cold gas thrusters. S-Band communications via were via either the low gain or high gain antenna. A thermal shield protected the spacecraft from solar radiation. The spacecraft instruments measured both interplanetary and Venusian magnetic fields, charged particles, and plasmas, as well as the radio refractivity and UV emissions of the Venusian atmosphere. The mission was termed a success.
NASA NSSDC Master Catalog Description
The Mariner 5 spacecraft was the fifth in a series of spacecraft used for planetary exploration in the flyby mode. Mariner 5 was a refurbished backup spacecraft for the Mariner 4 mission and was converted from a Mars mission to a Venus mission. The project objectives were to pass within 2000 km of Venus to provide data on the structure of the planet's atmosphere and its radiation and magnetic field environment. Mariner 5 was also designed to return data on the interplanetary environment before and after planetary encounter.
The Mariner 5 spacecraft consisted of an octagonal magnesium frame, 127 cm across a diagonal and 45.7 cm high. Four solar panels were attached to the top of the frame. A 116.8 cm diameter high gain parabolic antenna was mounted at the top of the frame as well. An omnidirectional low gain antenna and the magnetometer were mounted on a 223.5 cm tall mast next to the high gain antenna. The overall height of the spacecraft was 289 cm. The octagonal frame housed the electronic equipment, cabling, midcourse propulsion system, and attitude control gas supplies and regulators. Most of the science experiments were mounted on the outside of the frame. Science instruments were a magnetometer, S-band occultation telemetry, UV photometer, trapped radiation detector, dual frequency propagation beacon, Faraday cup, and celestial mechanics.
Power was supplied by 17,640 n/p solar cells contained in the four solar panels with an end-to-end span of 550 cm, which could provide 555 W at Venus. A rechargeable 1200 W-hr silver-zinc battery was also used for maneuvers and backup. Monopropellant hydrazine was used for propulsion, via a 4-jet vane vector control 222-N motor installed on one of the sides of the octagonal structure. Attitude control was provided by 12 cold nitrogen gas jets mounted on the ends of the solar panels and three gyros. Positional information was provided by two primary Sun sensors, secondary Sun sensors, an Earth sensor, a planet sensor, a Venus terminator sensor, and Canopus star tracker.
Telecommunications equipment consisted of a dual, S-band 6.5-W triode cavity amp/10.5-W TWTA transmitter and a single receiver which could send and receive data via the low- and high-gain antennas at 8 1/3 or 33 1/3 bps. Data could also be stored on a tape recorder for later transmission. All operations were controlled by a command subsystem. The central computer and sequencer operated stored time-sequence commands. Temperature control was maintained through the use of adjustable louvers, deployable sunshade, multilayer insulating blankets, polished aluminum shields, surface treatments, and reference units mounted on three solar panels.
Mariner 5 was launched from the Eastern Test Range of Cape Kennedy on an Atlas Agena Don 14 June 1967 at 06:01:00 UT. A mid-course correction (a 17.66 second burn) was made on 19 June. Mariner 5 reached Venus on 19 October and began transmitting data. Closest approach at an altitude of 4094 km occurred at 17:34:56 UT. At this time Venus was approximately 79.5 million km from Earth. Mariner 5 passed in front of Venus' orbit and was occulted from Earth for approximately 26 minutes. Data transmissions occurred after the encounter. Contact was lost on 4 December 1967, but was temporarily regained on 14 October 1968. The spacecraft is now in heliocentric orbit. The spacecraft instruments measured both interplanetary and Venusian magnetic fields, charged particles, and plasmas, as well as the radio refractivity and UV emissions of the Venusian atmosphere. The mission was termed a success. Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.
Credit: Manufacturer Image
Mariner 5 flew by Venus on October 19, 1967 at an altitude of 3,990 kilometres. With more sensitive instruments than its predecessor Mariner 2, Mariner 5 was able to shed new light on the hot, cloud-covered planet and on conditions in interplanetary space. Operations of Mariner 5 ended in November 1967. The spacecraft instruments measured both interplanetary and Venusian magnetic fields, charged particles, and plasmas, as well as the radio refractivity and UV emissions of the Venusian atmosphere.