Beyond_Earth-_A_Chronicle_of_Deep_Space_Exploration_1958-2016.pdf

Luna 18

Nation: USSR (79)

Objective(s): lunar sample return

Spacecraft: Ye-8-5 (no. 407)

Spacecraft Mass: 5,725 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 256-01 + 11S824 no. 0601L)

A ground model of the Apollo 15 Particles and Fields Satellite. Credit: NASA

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Launch Date and Time: 2 September 1971 / 13:40:40 UT

Launch Site: NIIP-5 / Site 81/24

Scientific Instruments:

• 1. stereo imaging system
• 2. remote arm for sample collection
• 3. radiation detector
• 4. radio altimeter

Results: This was the seventh Soviet attempt to recover soil samples from the surface of the Moon and the first after the success of Luna 16. After two mid-course corrections on 4 and 6 September 1971, Luna 18 entered a circular orbit around the Moon on 7 September at 100 kilometers altitude with an inclination of 35°, an orbit that was off-nominal since the orbit insertion engine cut off 15 seconds earlier than planned. To save propellant, mission planners decided to conduct one (instead of two) orbital corrections to bring the spacecraft into the proper orbit for descent. This firing, held outside direct radio contact, was also not nominal, leaving the vehicle in a 93.4 × 180.3-kilometer orbit (instead of 16.9 × 123.9 kilometers). Telemetry data showed that the pitch program was two orders less than expected due to the low effectiveness of one of the orientation engines, which was working only on fuel and not oxidizer. After a subsequent orbital correction, on 11 September, the vehicle began its descent to the lunar surface. However, due to its off-nominal orbit, the same orientation engine completely failed on all three axes (pitch, yaw, roll). As a result, the roll angle was 10° less than the computed value (since the other orientation engines were not able to fully compensate). Contact with the spacecraft was abruptly lost at 07:47:16.5 UT at the previously determined point of lunar landing. Impact coordinates were 3° 34′ N / 56° 30′ E near the edge of the Sea of Fertility. Officially, the Soviets announced that "the lunar landing in the complex mountainous conditions proved to be unfavorable." Later, in 1975, the Soviets published data from Luna 18's continuous-wave radio altimeter which determined the mean density of the lunar topsoil.

Luna 19

Nation: USSR (80)

Objective(s): lunar orbit

Spacecraft: Ye-8LS (no. 202)

Spacecraft Mass: 5,330 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 257-01 + 11S824 no. 4001L)

Launch Date and Time: 28 September 1971 / 10:00:22 UT

Launch Site: NIIP-5 / Site 81/24

Scientific Instruments:

• 1. 2 TV cameras
• 2. gamma-ray spectrometer (ARL)
• 3. RV-2NLS radiation detector
• 4. SIM-RMCh meteoroid detector
• 5. SG-59M magnetometer
• 6. radio altimeter

Results: Luna 19 was the first "advanced" lunar orbiter whose design was based upon the same Ye-8 class bus used for the lunar rovers and the sample collectors. For these orbiters, designated Ye-8LS, the basic "lander stage" was topped off by a wheelless Lunokhod-like frame that housed all scientific instrumentation in a pressurized container. Luna 19 entered orbit around the Moon on 2 October 1972 with parameters of 141.2 × 133.9 kilometers at 40.5° inclination. After two mid-course corrections on 29 September and 1 October, a final correction on 6 October was to put the spacecraft into proper altitude to begin its imaging mission. However, a failure in a gyro-platform in the orientation system pointed the vehicle incorrectly and Luna 19 ended up in a much higher orbit than planned. As a result, the original high-resolution imaging mission as well as use of the radio altimeter was canceled. Instead, the mission was reoriented to provide panoramic images of the mountainous areas of the Moon between 30° and 60° S latitude and between 20° and 80° E longitude. Because the vehicle was in a contingency spin-stabilized mode, the images unfortunately came out blurred (41 pictures were returned). In an article in Pravda on 17 February 1973, Lavochkin Chief Designer Sergey Kryukov (1918–2005) noted that "prominence in the scientific mission of the Luna 19 station was given to the study of the gravitational field of the Moon" and the location of mascons. Occultation experiments in May and June 1972 allowed scientists to determine the concentration of charged particles at an altitude of 10 kilometers. Additional studies of the solar wind were coordinated with those performed by the Mars 2 and 3 orbiters and Veneras 7 and 8. The gamma-ray spectrometer apparently failed to provide any data. Communications with Luna 19 was lost on 1 November 1972 after 13 months of continuous operation (over 4,000 orbits of the Moon), far exceeding the planned lifetime of three months.

Luna 20

Nation: USSR (81)

Objective(s): lunar sample return

Spacecraft: Ye-8-5 (no. 408)

Spacecraft Mass: 5,725 kg

Mission Design and Management: GSMZ imeni Lavochkina

Launch Vehicle: Proton-K + Blok D (8K82K no. 258-01 + 11S824 no. 0801L)

Launch Date and Time: 14 February 1972 / 03:27:58 UT

Launch Site: NIIP-5 / Site 81/24

Scientific Instruments:

• 1. stereo imaging system
• 2. remote arm for sample collection
• 3. radiation detector
• 4. radio altimeter

Results: This, the eighth Soviet spacecraft launched to return lunar soil to Earth, was sent to complete the mission that Luna 18 had failed to accomplish. After a four-and-a-half day flight to the Moon that included a single mid-course correction on 15 February, Luna 20 entered orbit around the Moon on February 18. Initial orbital parameters were 100 × 100 kilometers at 65° inclination. Three days later at 19:13 UT, the spacecraft fired its main engine for 267 seconds to begin descent to the lunar surface. A second firing at an altitude of 760 meters further reduced velocity before Luna 20 set down safely on the Moon at 19:19:09 UT on 21 February 1972 at coordinates 3° 32′ N / 56° 33′ E (as announced at the time), only 1.8 kilometers from the crash site of Luna 18, in a highland region between Mare Fecunditatis and Mare Crisium. The spacecraft settled on a slope of about 8° to 10°. After landing, the imaging system was used to locate a scientifically promising location to collect a sample, which was done on 23 February, but in stages due to increased soil resistance. After the sample was safely collected, the spacecraft's ascent stage lifted off at 22:58 UT on 22 February and quickly accelerated to 2.7 kilometers/second velocity, sufficient to return to Earth. The small spherical capsule parachuted down safely on an island in the Karkingir river, 40 kilometers northwest of the town of Dzhezkazgan in Kazakhstan at 19:12 UT on 25 February 1972. The 55-gram soil sample differed from that collected by Luna 16 in that the majority (50–60%) of the rock particles in the newer sample were ancient anorthosite (which consist largely of feldspar) rather than the basalt of the earlier one (which contained about 1–2% of anorthosite). They were, in fact, quite similar to samples collected by the Apollo 16 astronauts in April 1972. Like the Luna 16 soil, samples of the Luna 20 collection were exchanged with NASA officials who delivered a sample from the Apollo 15 mission, the exchange taking place on 13 April 1972. Samples were also shared with scientists from France, Czechoslovakia, Great Britain (both Luna 16 and 20), and India. Also, as with Luna 16, in 2009 and 2010, images from NASA's Lunar Reconnaissance Orbiter (LRO) were used to more precisely identify Luna 20's landing site as 3.7866° N / 56.6242° E.

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The plaque carried on Pioneers 10 and 11 showed a human male and female standing next to a Pioneer spacecraft. At the top left are two hydrogen atoms, each in a different energy state. Note the planets of the solar system at the bottom, with a line tracing Pioneer to the third planet from the Sun. Credit: NASA

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Pioneer 10

Nation: USA (51)

Objective(s): Jupiter flyby

Spacecraft: Pioneer-F

Spacecraft Mass: 258 kg

Mission Design and Management: NASA / ARC

Launch Vehicle: Atlas Centaur (AC-27 / Atlas 3C no. 5007C / Centaur D-1A)

Launch Date and Time: 2 March 1972 / 01:49:04 UT

Launch Site: Cape Kennedy / Launch Complex 36A

Scientific Instruments:

• 1. imaging photopolarimeter
• 2. helium vector magnetometer (HVM)
• 3. infrared radiometer
• 4. quadrispherical plasma analyzer
• 5. ultraviolet photometer
• 6. charged particle instrument (CPI)
• 7. cosmic ray telescope (CRT)
• 8. Geiger tube telescope (GTT)
• 9. Sisyphus asteroid/meteoroid detector (AMD)
• 10. meteoroid detectors
• 11. trapped radiation detector (TRD)

Results: Pioneer 10, the first NASA mission to the outer planets, garnered a series of firsts perhaps unmatched by any other robotic spacecraft in the space era: the first vehicle placed on a trajectory to escape the solar system into interstellar space; the first spacecraft to fly beyond Mars; the first to fly through the asteroid belt; the first to fly past Jupiter; and the first to use all-nuclear electrical power (two SNAP-19 radioisotope thermal generators [RTGs] capable of delivering about 140 W during the Jupiter encounter). After launch by a three-stage version of the Atlas Centaur (with a TE-M-364-4 solid propellant engine modified from the Surveyor lander), Pioneer 10 reached a maximum escape velocity of 51,682 kilometers/hour, faster than any previous human-made object at that point in time. Controllers carried out two course corrections, on 7 March and 26 March, the latter to ensure an occultation experiment with Jupiter's moon Io. There were some initial problems during the outbound voyage when direct sunlight caused heating problems, but nothing to endanger the mission. On 15 July 1972, the spacecraft entered the asteroid belt, emerging in February 1973 after a 435 million-kilometer voyage. During this period, the spacecraft encountered some asteroid hits (although much less than expected) and also measured the intensity of Zodiacal light in interplanetary space. In conjunction with Pioneer IX (in solar orbit), on 7 August, Pioneer 10 recorded details of one of the most violent solar storms in recent record. At 20:30 UT on 26 November, the spacecraft reported a decrease in the solar wind from 420 to 250 kilometers/second and a 100-fold increase in temperature, indicating that it was passing through the front of Jupiter's bow shock where the solar wind clashed with the planet's magnetosphere. In other words, it had entered Jupiter's magnetosphere. By 1 December, Pioneer 10 was returning better images of the planet than possible from Earth. (It had already begun imaging as early as 6 November 1973). Command-and-return time was up to 92 minutes by this time. Pioneer 10's closest approach to Jupiter was at 02:26 UT on 4 December 1973 when the spacecraft raced by the planet at a range of 130,354 kilometers at a velocity of approximately 126,000 kilometers/hour. Of the spacecraft's 11 scientific instruments, 6 operated continuously through the encounter. The spacecraft passed by a series of Jovian moons, obtaining photos of Callisto, Ganymede, and Europa (but not of Io, as the photopolarimeter succumbed to radiation by that time). Approximately 78 minutes after the closest approach, Pioneer 10 passed behind Jupiter's limb for a radio occultation experiment. In addition, the infrared radiometer provided further information on the planet's atmosphere. Between 6 November and 31 December, the vehicle took about 500 pictures of Jupiter's atmosphere with a highest resolution of 320 kilometers, clearly showing such landmarks as the Great Red Spot. The encounter itself was declared over on 2 January 1974. Pioneer 10 fulfilled all objectives except one due to false commands triggered by Jupiter's intense radiation. Based on incoming data, scientists identified plasma in Jupiter's magnetic field. The spacecraft crossed Saturn's orbit in February 1976, recording data that indicated that Jupiter's enormous magnetic tail, almost 800 million kilometers long, covered the whole distance between the two planets. Still operating nominally, Pioneer 10 crossed the orbit of Neptune (then the outermost planet) on 13 June 1983, thus becoming the first human-made object to go beyond the furthest planet. NASA maintained routine contact with Pioneer 10 for over two decades until 19:35 UT on 31 March 1997 (when the spacecraft was 67 AU from Earth) when routine contact was terminated due to budgetary reasons. Intermittent contact, however, continued, but only as permitted by the onboard power source, with data collections from the Geiger tube telescope and the charged particle instrument. Until 17 February 1998, Pioneer 10 was the farthest human-made object in existence (69.4 AU) when it was passed by Voyager 1. A NASA ground team received a signal on the state of spacecraft systems (still nominal) on 5 August 2000. The spacecraft returned its last telemetry data on 27 April 2002 and less than a year later, on 23 January 2003, it sent its last signal back to Earth when it was 12.23 billion kilometers from Earth. That signal took 11 hours and 20 minutes to reach Earth. By that time, it was clear that the spacecraft's RTG power source had decayed, thus delivering insufficient power to the radio transmitter. A final attempt to contact Pioneer 10 on 4 March 2006 failed. Originally designed for a 21-month mission, the mission's lifetime far exceeded expectations. By 5 November 2017, the inert Pioneer 10 spacecraft was roughly 118.824 AUs (or 17.776 billion kilometers) from Earth, a range second only to Voyager 1. The spacecraft is generally heading in the direction of the red star Aldebaran which forms the eye of the Taurus constellation. It is expected to pass by Aldebaran in about two million years. Pioneer 10 is heading out of the solar system in a direction very different from the two Voyager probes and Pioneer 11, i.e., towards the nose of the heliosphere in an upstream direction relative to the inflowing interstellar gas. In case of an intercept by intelligent life, Pioneer 10 carries an aluminum plaque with diagrams of a man and a woman, the solar system, and its location relative to 14 pulsars. The expectation is that such intelligent life would be able to interpret the diagram to determine the position of the Sun (and thus, Earth) at the time of launch relative to the Pulsars.