Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

Composite of images taken by the Soviet Mars 5 spacecraft from Martian orbit on 23 February 1974. Credit: Don Mitchell

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Mars 6

Nation: USSR (88)

Objective(s): Mars flyby and Mars landing

Spacecraft: M-73P (3MP no. 50P)

Spacecraft Mass: 3,880 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 281-01 + 11S824 no. 1901L)

Launch Date and Time: 5 August 1973 / 17:45:48 UT

Launch Site: NIIP-5 / Site 81/23

Scientific Instruments:

Spacecraft Bus:

• 1. magnetometer
• 2. plasma traps
• 3. cosmic ray sensors
• 4. micrometeoroid detectors
• 5. Gémeaux-S1 and Gémeaux-T instruments for study of solar proton and electron fluxes
• 6. Stereo-5 antenna

Lander:

• 1. thermometer
• 2. barometer
• 3. accelerometer
• 4. radio-altimeter
• 5. mass spectrometer
• 6. soil analyzer

The Soviet Mars 6 spacecraft. The lander aeroshell is visible on top. Credit: Don Mitchell

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Results: Mars 6 was one of two combination flyby-lander launched by the Soviet Union during the 1973 launch period. The landers were very similar in design to the Mars 2 and Mars 3 landers dispatched by the Soviets in 1971, except the spacecraft was now comprised of a flyby vehicle (instead of an orbiter) and a 1,000-kilogram lander. Mars 6 completed its first mid-course correction en route to Mars at 23:45 UT on 12 August 1973, but immediately a tape recorder on board failed, forcing controllers to use a backup. Then on 3 September, there was a major failure in the telemetry system that transmitted scientific and operations data from the spacecraft. Only two channels remained operational, neither of which provided the ground with any direct data on the status of the flyby vehicle's systems. Controllers could only use a time-consuming "playback" mode for the reception of data. Ultimately, the flyby spacecraft automatically performed all its functions and at 05:01:56 UT (signal reception time) on 12 March 1974, the lander successfully separated from its mother ship at a distance of 46,000 kilometers from Mars. About 4 hours later, at 09:05:53 UT, it entered the Martian atmosphere at a velocity of 5,600 meters/second. The parachute system deployed correctly at an altitude of 20 kilometers (at 09:08:32) when speed had been reduced to about 600 meters/second, and scientific instruments began to collect and transmit data (to the flyby vehicle) as the probe descended. The only useful data was, however, directly from the lander to Earth, and its information was rather "weak" and difficult to decode. It appeared that the lander was rocking back and forth under its parachute far more vigorously than expected. Nevertheless, Mars 6 returned the first direct measurements of the temperature and pressure of the Martian atmosphere as well as its chemical composition (using the radio-frequency mass spectrometer) to Earth. The data indicated that argon made up about one-third of the Martian atmosphere. Moments before the expected landing, the ground lost contact with the probe. The last confirmed data was information on ignition of the soft-landing engines received about 2 seconds before impact, the probe landing at 09:11:05 UT at 23.9° S / 19.5° W. Later investigation never conclusively identified a single cause of loss of contact. Probable reasons included failure of the radio system or landing in a geographically rough area. The Mars 6 flyby bus, meanwhile, collected some scientific information during its short flyby (at a minimum range of 1,600 kilometers to the surface) before heading into heliocentric orbit.

Mars 7

Nation: USSR (89)

Objective(s): Mars flyby and Mars landing

Spacecraft: M-73P (3MP no. 51P)

Spacecraft Mass: 3,880 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 281-02 + 11S824 no. 2001L)

Launch Date and Time: 9 August 1973 / 17:00:17 UT

Launch Site: NIIP-5 / Site 81/24

Scientific Instruments:

Spacecraft Bus:

• 1. magnetometer
• 2. plasma traps
• 3. KM-73 cosmic ray detector
• 4. micrometeoroid detectors
• 5. Gémeaux-S1 and Gémeaux-T instruments for study of solar proton and electron fluxes
• 6. Stereo-5 antenna

Lander:

• 1. thermometer
• 2. barometer
• 3. accelerometer
• 4. radio-altimeter
• 5. mass spectrometer
• 6. soil analyzer

Results: Mars 7 was the last of the four Soviet spacecraft sent to Mars in the 1973 launch period (although it arrived at Mars prior to Mars 6). On its way to Mars, the spacecraft performed a single mid-course correction at 20:00 UT on 16 August 1973. En route to Mars, there were failures in the communications systems, and controllers were forced to maintain contact via the only remaining radio-communications complex. On 9 March 1974, the flyby spacecraft ordered the lander capsule to separate for its entry into the Martian atmosphere. Although the lander initially refused to "accept" the command to separate, it eventually did. Ultimately, the lander's main retro-rocket engine failed to fire to initiate entry into the Martian atmosphere. As a result, the lander flew by the planet at a range of 1,300 kilometers and eventually entered heliocentric orbit. The flyby probe did, however, manage to collect data during its encounter with the Red Planet while contact was maintained until 25 March 1974. Both the failures on Mars 4 (computer failure) and 7 (retro-rocket ignition failure) were probably due to the faulty transistors installed in the circuits of the onboard computer which were detected prior to launch. Data from Mars 7 was being analyzed as late as 2003 when researchers published results based on data collected by the KM-73 cosmic ray detector in September 1973 en route to Mars.

Mariner 10

Nation: USA (55)

Objective(s): Mercury flyby, Venus flyby

Spacecraft: Mariner-73J / Mariner-J

Spacecraft Mass: 502.9 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Atlas Centaur (AC-34 / Atlas 3D no. 5014D / Centaur D-1A)

Launch Date and Time: 3 November 1973 / 05:45:00 UT

Mariner 10 took this image of Venus on 5 February 1974. The original photo was color-enhanced to provide more contrast in Venus's cloudy atmosphere. Credit: NASA

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Launch Site: Cape Canaveral / Launch Complex 36B

Scientific Instruments:

• 1. 2 telescopes/cameras
• 2. infrared radiometer
• 3. ultraviolet airglow spectrometer
• 4. ultraviolet occultation spectrometer
• 5. magnetometer
• 6. charged particle telescope
• 7. plasma analyzer

Results: Mariner 10 was the first spacecraft sent to the planet Mercury; the first mission to explore two planets (Mercury and Venus) during a single mission; the first to use gravity-assist to change its flight-path; the first to return to its target after an initial encounter; and the first to use the solar wind as a major means of spacecraft orientation during flight. The primary goal of the Mariner 10 was to study the atmosphere (if any), surface, and physical characteristics of Mercury. Soon after leaving Earth orbit, the spacecraft returned striking photos of both Earth and the Moon as it sped to its first destination, Venus. During the coast, there were numerous technical problems, including malfunctions in the high-gain antenna and the attitude control system. In January 1974, Mariner 10 successfully returned data (sans photographs) on Comet C/1973 E1 Kohoutek, the first time a spacecraft returned data on a long-period comet. After mid-course corrections on 13 November 1973 and 21 January 1974, Mariner 10 approached Venus for a gravity-assist maneuver to send it towards Mercury. On 5 February 1974, the spacecraft began returning images of Venus, the first picture showing the day-night terminator of the planet as a thin bright line. Overall, Mariner 10 returned a total of 4,165 photos of Venus and collected important scientific data during its encounter. Closest flyby range was 5,768 kilometers at 17:01 UT on 5 February. Assisted by Venusian gravity, the spacecraft now headed to the innermost planet, which it reached after another mid-course correction on 16 March 1974. As Mariner 10 approached Mercury, photos began to show a very Moon-like surface with craters, ridges, and chaotic terrain. The spacecraft's magnetometers revealed a weak magnetic field. Radiometer readings suggested nighttime temperatures of –183°C and maximum daytime temperatures of 187°C. Closest encounter came at 20:47 UT on 29 March 1974 at a range of 703 kilometers. An occultation experiment as the vehicle crossed behind the nightside of the planet indicated a lack of an atmosphere or ionosphere. Leaving Mercury behind, the spacecraft looped around the Sun and headed back to its target, helped along by subsequent course corrections on 9 May, 10 May, and 2 July 1974. Mariner 10 flew by Mercury once more at 20:59 UT on 21 September 1974 at a more distant 48,069 kilometers range, adding imagery of the southern polar region. The spacecraft used solar pressure on its solar panels and high-gain antenna for attitude control. Mariner 10 once again sped away from Mercury before a final and third encounter with Mercury, enabled by three maneuvers (on 30 October 1974, 13 February 1975, and 7 March 1975), the last one actually to avoid impact with the planet. The third flyby, at 22:39 UT on 16 March 1975, was the closest to Mercury, at a range of 327 kilometers. Because of the failure of a tape recorder and restrictions in the rate of data reception, only the central quarter of each of 300 high resolution images was received during this encounter. Last contact with the spacecraft was at 12:21 UT on 24 March 1975 after the spacecraft exhausted its supply of gas for attitude control. Overall, Mariner 10 returned over 2,700 pictures during its three Mercury flybys that covered nearly half of the planet's surface. Some of the images showed detail as small as 100 meters wide. Perhaps the most impressive surface feature was the Caloris basin, characterized by a set of concentric rings and ridges and about 2,500 kilometers in diameter. The mission was the last visit to Mercury by a robotic probe for more than 30 years.

Luna 22

Nation: USSR (90)

Objective(s): lunar orbit

Spacecraft: Ye-8LS (no. 206)

Spacecraft Mass: 5,700 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 282-02 + 11S824 no. 0701L)

Launch Date and Time: 29 May 1974 / 08:56:51 UT

Launch Site: NIIP-5 / Site 81/24

Scientific Instruments:

• 1. 2 TV cameras
• 2. ARL-M gamma-ray spectrometer
• 3. RV-2N-1 radiation detector
• 4. SIM-RMCh meteoroid detector
• 5. SG-70 magnetometer
• 6. AKR-1 low-frequency space radio wave detector
• 7. 8 pairs of friction materials with different lubricants
• 8. 12 kinds of coatings with different reflective properties
• 9. Vega radio-altimeter

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Results: Luna 22 was the second of two "advanced" lunar orbiters (the first being Luna 19) designed to conduct extensive scientific surveys from orbit. Launched about a year after termination of Lunokhod 2 operations on the lunar surface, Luna 22 performed a single mid-course correction en route the Moon on 30 May before entering lunar orbit on 2 June 1974. Initial orbital parameters were 219 × 222 kilometers at 19° 35′ inclination. An orbital correction on 9 June put the spacecraft in its nominal orbit of 244 × 25 kilometers for its primary imaging mission. The spacecraft carried out four mapping sessions; a fifth one was canceled due to a significant decrease in the perilune from 24.5 kilometers (on 9 June) to 15.4 kilometers (on 12 June). Nevertheless, Luna 22 provided the best Soviet imagery of the Moon. In addition to its primary mission of surface photography, Luna 22 also performed investigations to determine the chemical composition of the lunar surface, recorded meteoroid activity, searched for a lunar magnetic field, measured solar and cosmic radiation flux, and continued studies of the irregular magnetic field. Through various orbital changes—including a burn on 11 November 1974 to put the vehicle into a high 1,437 × 171-kilometer orbit to conduct gravitational experiments—Luna 22 performed without any problems, continuing to return photos 15 months into the mission, although its primary mission ended by 2 April 1975. The spacecraft's maneuvering propellant was finally depleted on 2 September and the highly successful mission was formally terminated in early November 1975. Luna 22 remains the final Soviet or Russian dedicated lunar orbiter.