Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

Results: Mars 2 was the first of two orbiter-lander combination spacecraft sent to Mars by the Soviet Union during the 1971 launch period. The orbiters were roughly cylindrical structures fixed to a large propellant tank base. The landers were egg-shaped modules with petals that would open up on the Martian surface. The 1,000 kilogram landers (of which 355 kilograms was the actual capsule on the surface) were fastened to the top of the bus and protected by a braking shell for entry into the Martian atmosphere. After jettisoning the shell, the landers would deploy parachutes to descend to the Martian surface. Each lander also carried 4-kilogram mini-rovers called PrOP-M (for Pribor otsenki prokhodimosti-Mars, or Device to Evaluate Mobility—Mars), a box-shaped robot that was equipped with skids; the device would move by moving the body forward (at a speed of 1 meter/minute) with the ski resting on the soil. The range of the device, connected by an umbilical cord to supply power and transmit data, was 15 meters. PrOP-M carried a penetrometer and a radiation densimeter. If the device ran into an obstacle, sensors at the front would send a signal to an automated control system on the lander, which would then send a command to back up PrOP-M, turn it "right" (if the obstacle was towards the left) or "left" (if the obstacle was towards the right), and then take one step forward again. As Mars 2 made its way to the Red Planet, controllers performed two successful mid-course corrections, on 17 June and 20 November 1971. On 27 November 1971, Mars 2 implemented its final mid-course correction after which the lander probe separated to initiate atmospheric entry. At this point, the onboard computer was designed to implement final corrections to the trajectory and spin up the lander around its longitudinal axis and then fire a solid propellant engine to initiate reentry in a specific direction. As it happened, after the final course correction, the trajectory of the spacecraft had been so accurate that there was no need for further corrective measures. Because of pre-programmed algorithms that simply assumed a deviated trajectory, the lander was put into an incorrect attitude after separation to compensate for the "error." When the reentry engine fired, the angle of entry proved to be far too steep. The parachute system never deployed and the lander eventually crashed onto the Martian surface at 4° N / 47° W. It was the first human-made object to make contact with Mars. The Mars 2 orbiter meanwhile successfully entered orbit around Mars at 20:19 UT on 27 November 1971. Parameters were 1,380 × 25,000 kilometers at 48.9° inclination, with an orbital period of 1,080 minutes, slightly less than the expected 1,440 minutes. In a clear obfuscation of the truth, the Soviets claimed that one of the two French Stéréo-1 instruments was lost with the other instruments on Mars 2, when in fact, Stéréo-1 was not carried on Mars 2 but the earlier failed Kosmos 419. [See Mars 3 for Mars 2 orbiter program.]

Mars 3

Nation: USSR (78)

Objective(s): Mars orbit and landing

Spacecraft: M-71 (4M no. 172)

Spacecraft Mass: 4,650 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 249-01 + 11S824 no. 1301L)

Launch Date and Time: 28 May 1971 / 15:26:30 UT

Launch Site: NIIP-5 / Site 81/23

Scientific Instruments:

Orbiter:

• 1. infrared bolometer (radiometer)
• 2. microwave radiometer (radiotelescope)
• 3. infrared photometer (CO2 gas absorption strips)
• 4. IV-2 interference-polarized photometer
• 5. photometer to measure brightness distribution
• 6. 4-channel UV photometer
• 7. imaging system (two cameras, each capable of 480 images)
• 8. ferrozoid tricomponent magnetometer
• 9. ion trap
• 10. RIEP-2801 spectrometer for charged particles
• 11. cosmic ray detector
• 12. radiotransmitter (for determination of structure of atmosphere through refraction)
• 13. D-127 charged particle traps [unconfirmed]
• 14. Stéréo-1 radio-astronomy experiment
• 15. modulation-type ion trap

Lander:

• 1. gamma-ray spectrometer
• 2. x-ray spectrometer
• 3. thermometer
• 4. anemometer
• 5. barometer
• 6. imaging system (two cameras)
• 7. mass spectrometer
• 8. penetrometer (on PrOP-M)
• 9. gamma-ray densitometer (on PrOP-M)

Results: Like its predecessor, Mars 3 was successfully sent on a trajectory to the Red Planet. The spacecraft completed three mid-course corrections on 8 June, 14 November, and 2 December 1971. At 09:14 UT on 2 December 1971, the lander separated from the orbiter and 4.5 hours later began entry into the Martian atmosphere. Finally, at 13:47 UT, the probe successfully set down intact on the Martian surface becoming the first human-made object to perform a survivable landing on the planet. Landing coordinates were 44.90° S / 160.08° W. The bus meanwhile entered orbit around Mars with parameters of 1,530 × 214,500 kilometers at 60.0° inclination, significantly more eccentric than originally planned—at least 11 times higher than nominal. Immediately after landing, at 13:50:35 UT, the lander probe began transmitting a TV image of the Martian surface although transmissions abruptly ceased after 14.5 seconds (or 20 seconds according to some sources). Because of a violent dust storm that raged across the planet, controllers surmised that coronal discharge may have shorted all electric instrumentation on the lander. The received image showed only a gray background with no detail, probably because the two imaging "heads" had still not deployed in 20 seconds to their full height to see the surface. After the initial contact, the ground lost all contact with the lander probe. The Mars 3 orbiter, like the Mars 2 orbiter, had problems with its imaging mission. Because the orbiters had to perform their imaging mission soon after entering orbit—mainly because the chemicals on board for developing film had a finite lifetime—they could not wait until the dust storms subsided on the surface. As a result, the photographs from both orbiters showed few details of the surface. On 23 January 1972, Pravda noted that "the dust storm is still making photography and scientific measurement of the planet difficult" but added on 19 February that "information obtained [more recently] shows that the dust storm has ended." Later analysis showed that the dust storm began during the first 10 days of October and lasted three months although the atmosphere contained residual dust until late January. Additionally, controllers had set the cameras at the wrong exposure setting, making the photos far too light to show much detail. Despite the failure of the imaging mission, both orbiters carried out a full cycle of scientific experiments returning data on properties of the surface and atmosphere—including on the nature and dynamics of the dust storm and water content in the Martian atmosphere—until contact was lost almost simultaneously, according to Lavochkin, in July 1972. TASS announced completion of both orbital missions on 23 August 1972. The French Stéréo-1 instrument on Mars 3 operated successfully for 185 hours over nearly seven months returning a megabyte of data on solar radiation. In April 2013, NASA announced that its Mars Reconnaissance Orbiter (MRO) may have imaged hardware from Mars 3, including its parachute, heat shield, braking engine, and the lander itself. These were found in 2008 by a community of Russian space enthusiasts who were following the mission of Curiosity.

Mariner 9

Nation: USA (49)

Objective(s): Mars orbit

Spacecraft: Mariner-71I / Mariner-I

Spacecraft Mass: 997.9 kg

Mission Design and Management: NASA / JPL

Launch Vehicle: Atlas Centaur (AC-23 / Atlas 3C no. 5404C / Centaur D-1A)

Launch Date and Time: 30 May 1971 / 22:23:04 UT

Launch Site: Cape Kennedy / Launch Complex 36B

Scientific Instruments:

• 1. imaging system
• 2. ultraviolet spectrometer
• 3. infrared spectrometer
• 4. infrared radiometer

Results: Mariner 9 was the second in the pair of identical spacecraft launched in 1971 to orbit Mars. The first spacecraft, Mariner 8, failed to reach Earth orbit. Based on a wide octagonal structure, these vehicles used a bi-propellant propulsion system with a fixed thrust of 136 kgf for orbital insertion around Mars. All scientific instrumentation on the spacecraft were mounted on a movable scan platform "underneath" the main bodies. The span of the spacecraft over its extended solar panels was 6.9 meters. After an en route mid-course correction on 5 June 1971, at 00:18 UT on 14 November 1971, Mariner 9 ignited its main engine for 915.6 seconds to become the first human-made object to enter orbit around a planet. Initial orbital parameters were 1,398 × 17,916 kilometers at 64.3° inclination. (Another firing on the fourth revolution around Mars refined the orbit to 1,394 × 17,144 kilometers at 64.34° inclination). The primary goal of the mission was to map about 70% of the surface during the first three months of operation. The dedicated imaging mission began in late November, but because of the major dust storm at the planet during this time, photos of the planet taken prior to about mid-January 1972 did not show great detail. Once the dust storm had subsided, from 2 January 1972 on, Mariner 9 began to return spectacular photos of the deeply pitted Martian landscape, for the first time showing such features as the great system of parallel rilles stretching more than 1,700 kilometers across Mare Sirenum. The vast amount of incoming data countered the notion that Mars was geologically inert. There was some speculation on the possibility of water having existed on the surface during an earlier period, but the spacecraft data could not provide any conclusive proof. By February 1972, the spacecraft had identified about 20 volcanoes, one of which, later named Olympus Mons, dwarfed any similar feature on Earth. Based on data from Mariner 9's spectrometers, it was determined that Olympus Mons, part of Nix Olympica—a "great volcanic pile" possibly formed by the eruption of hot magma from the planet's interior—is about 15–30 kilometers tall and has a base with a diameter of 600 kilometers. Another major surface feature identified was Valles Marineris, a system of canyons east of the Tharsis region that is more than 4,000 kilometers long, 200 kilometers wide, and in some areas, up to 7 kilometers deep. On 11 February 1972, NASA announced that Mariner 9 had achieved all its goals although the spacecraft continued sending back useful data well into the summer. By the time of last contact at 22:32 UT on 27 October 1972 when it exhausted gaseous nitrogen for attitude control, the spacecraft had mapped 85% of the planet at a resolution of 1–2 kilometers, returning 7,329 photos (including at least 80 of Phobos and Deimos). Thus ended one of the great early robotic missions of the space age and undoubtedly one of the most influential. The spacecraft is expected to crash onto the Martian surface sometime around 2020.

Apollo 15 Particle and Fields Subsatellite

Nation: USA (50)

Objective(s): lunar orbit

Spacecraft: Apollo 15 P&FS

Spacecraft Mass: 35.6 kg

Mission Design and Management: NASA / MSC

Launch Vehicle: Apollo 15 CSM-112 (itself launched by Saturn V SA-510)

Launch Date and Time: 26 July 1971 / 13:34:00 UT (subsatellite ejection on 4 August 1971 / 20:13:19 UT)

Launch Site: Kennedy Space Center / Launch Complex 39A

Scientific Instruments:

• 1. magnetometer
• 2. S-band transponder
• 3. charged particle detectors

Results: This small satellite was deployed by the Apollo 15 crew—David R. Scott, Alfred M. Worden, and James B. Irwin—shortly before leaving lunar orbit. The probe was designed around a hexagonal structure with a diameter of 35.6 centimeters that was equipped with three instrument booms. Power supply came from solar panels and chemical batteries. The instruments measured the strength and direction of interplanetary and terrestrial magnetic fields, detected variations in the lunar gravity field, and measured proton and electron flux. The satellite confirmed Explorer XXXV's finding that while Earth's magnetic field deflects the incoming solar wind into a tail, the Moon acts as a physical barrier due to its weak field and creates a "hole" in the wind. An electronic failure on 3 February 1972 formally ended the mission. Although it originally had a one-year design life, all mission objectives were fulfilled.