Mariner 4
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| Mariner 4 | |
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| Organization | NASA |
|---|---|
| Mission type | Flyby |
| Flyby of | Mars |
| Launch date | November 28, 1964 at 14:22:01 UTC |
| Launch vehicle | Atlas-Agena D launch vehicle |
| Mission duration | November 28, 1964 to December 21, 1967 |
| NSSDC ID | 1964-077A |
| Mass | 260.68 kg |
| Power | 170 W |
| Orbital elements | |
| Semimajor axis | 199591220 km |
| Eccentricity | 0.17024754 |
| Inclination | 2.51 |
| Orbital period | 562.888 |
| Apoapsis | 233571130 km |
| Periapsis | 165611300 km |
Mariner 4 (Mariner-Mars 1964) was the fourth in a series of spacecraft intended for planetary exploration in a flyby mode and performed the first successful flyby of the planet Mars, returning the first pictures of the Martian surface. It captured the first images of another planet ever returned from deep space; their depiction of a cratered, seemingly dead world shook the scientific community.[1] Mariner 4 was designed to conduct closeup scientific observations of Mars and to transmit these observations to Earth. Other mission objectives were to perform field and particle measurements in interplanetary space in the vicinity of Mars and to provide experience in and knowledge of the engineering capabilities for interplanetary flights of long duration.
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[edit] Spacecraft and subsystems
The Mariner 4 spacecraft consisted of an octagonal magnesium frame, 1270 mm across a diagonal and 457 mm high. Four solar panels were attached to the top of the frame with an end-to-end span of 6.88 m, including solar pressure vanes which extended from the ends. A 1,168 mm diameter high gain parabolic antenna was mounted at the top of the frame as well. An omnidirectional low gain antenna was mounted on a 2235 mm tall mast next to the high gain antenna. The overall height of the spacecraft was 2.89 m. At the bottom center of the spacecraft the television camera was mounted on a scan platform. 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, in addition to the TV camera, were a magnetometer, dust detector, cosmic ray telescope, trapped radiation detector, solar plasma probe, and ionization chamber/Geiger counter.
Power was supplied by 28,224 solar cells contained in the four 176 x 90 cm solar panels, which could provide 310 W at Mars. A rechargeable 1200 W•h 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. Solar pressure vanes, each with an area of 0.65 square meter, were attached to the tips of the solar panels. Positional information was provided by four Sun sensors, and an Earth, a Mars, and a Canopus sensor.
Telecommunications equipment consisted of a dual, S-band 7 W triode cavity amp/10 W TWTA transmitter and a single receiver which could send and receive data via the low- and high-gain antennas at 8⅓ or 33⅓ bit/s. Data could also be stored on a tape recorder with a capacity of 5.24 million bits for later transmission. All operations were controlled by a command subsystem which could process any of 29 direct command words or 3 quantitative word commands for midcourse maneuvers. The central computer and sequencer operated stored time-sequence commands using a 38.4 kHz synchronization frequency as a time reference. Temperature control was achieved through the use of adjustable louvers mounted on six of the electronics assemblies, multilayer insulating blankets, polished aluminum shields, and surface treatments.
Instruments:
- Mars TV Camera
- Helium Magnetometer
- Cosmic-Ray Telescope
- Occultation
- Celestial Mechanics
[edit] Mission profile
[edit] Launch
After launch from Cape Canaveral Air Force Station Launch Complex 12 the protective shroud covering Mariner 4 was jettisoned and the Agena D/Mariner 4 combination separated from the Atlas D booster at 14:27:23 UTC on 28 November 1964. The Agena D first burn from 14:28:14 to 14:30:38 put the spacecraft into an Earth parking orbit and the second burn from 15:02:53 to 15:04:28 injected the craft into a Mars transfer orbit. Mariner 4 separated from the Agena D at 15:07:09 and began cruise mode operations. The solar panels deployed and the scan platform was unlatched at 15:15:00 and Sun acquisition occurred 16 minutes later.
[edit] Mars flyby
After 7½ months of flight involving one midcourse maneuver on 5 December 1964, the spacecraft flew by Mars on July 14 and July 15, 1965. Planetary science mode was turned on at 15:41:49 UT on 14 July. The camera sequence started at 00:18:36 UT on July 15 (7:18:49 p.m. EST on July 14) and 21 pictures using alternate red and green filters, plus 21 lines of a 22nd picture were taken. The images covered a discontinuous swath of Mars starting near 40° N, 170° E, down to about 35° S, 200° E, and then across to the terminator at 50° S, 255° E, representing about 1% of the planet's surface. The closest approach was 9,846 km from the Martian surface at 01:00:57 UT 15 July 1965 (8:00:57 p.m. EST 14 July). The images taken during the flyby were stored in the onboard tape recorder. At 02:19:11 UT Mariner 4 passed behind Mars as seen from Earth and the radio signal ceased. The signal was reacquired at 03:13:04 UT when the spacecraft reappeared. Cruise mode was then re-established. Transmission of the taped images to Earth began about 8.5 hours after signal reacquisition and continued until 3 August. All images were transmitted twice to ensure no data was missing or corrupt.
The spacecraft performed all programmed activities successfully and returned useful data from launch until 22:05:07 UT on 1 October 1965, when the distance from Earth (309.2 million km) and the antenna orientation temporarily halted signal acquisition.
[edit] Micrometeoroid hits and end of communications
Data acquisition resumed in late 1967. The cosmic dust detector registered 17 hits in a 15 minute span on 15 September, part of an apparent micrometeoroid shower which temporarily changed the spacecraft attitude and probably slightly damaged the thermal shield. Later it was speculated that the probe passed through the debris of Comet D/Swift, and even made a close flyby of that comet's possibly shattered nucleus at only 20 million kilometers.[1] [2]
On December 7 the gas supply in the attitude control system was exhausted, and on December 10 and 11 a total of 83 micrometeoroid hits were recorded which caused perturbation of the attitude and degradation of the signal strength. On 21 December 1967 communications with Mariner 4 were terminated.
[edit] Results
The total data returned by the mission was 5.2 million bits (about 634kB). All experiments operated successfully with the exception of the ionization chamber/Geiger counter which failed in February 1965 and the plasma probe, which had its performance degraded by a resistor failure on 6 December 1964. The images returned showed a Moon-like cratered terrain (which later missions showed was not typical for Mars, but only for the more ancient region imaged by Mariner 4). A surface atmospheric pressure of 4.1 to 7.0 mbar (410 to 700 pascal) and daytime temperatures of −100 degrees Celsius were estimated and no magnetic field was detected.
.jpg/120px-Mars_(Mariner_4).jpg) The first close-up image ever taken of Mars, this photo shows an area about 330 km across by 1200 km from limb to bottom of frame. |
 The best Mariner 4 image, showing craters. |
 Mosaic of frame 1&2. The Martian atmosphere is visible over the planet's limb. |
 Mosaic of frame 9&10. |
 Mosaic of frame 11&12. |
Images of craters and measurements of a thin atmosphere, indicating a relatively inactive planet exposed to the harshness of space, generally dissipated hopes of finding intelligent life on Mars. Life there had been the subject of speculation and science fiction for centuries. If there was life on Mars, after Mariner 4 most concluded it would probably be smaller, simpler forms.
Mariner 4 may have concluded the gradual change, in science fiction, from describing intelligent aliens as dwellers on other planets in our Solar System, to describing them as living on planets circling distant stars.
The total cost of the Mariner 4 mission is estimated at $83.2 million. Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.
[edit] See also
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[edit] Notes
- ^ Mariner IV - First Flyby of Mars: Some personal experiences, Bill Momsen, p.2, accessed 2008-04-22
