This simulated color global view of the surface of Venus taken by Magellan is centered at 180° E longitude. Data gaps in Magellan's data were filled in by information from Pioneer Venus. Most notably, the simulated hues are based on color images from the Soviet Venera 13 and Venera 14 spacecraft. Credit: NASA/JPL
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Galileo
Nation: USA (64) Objective(s): Jupiter orbit and atmospheric entry Spacecraft: Galileo (Orbiter and Entry Probe) Spacecraft Mass: 2,380 kg Mission Design and Management: NASA / JPL Launch Vehicle: STS-34R Atlantis Launch Date and Time: 18 October 1989 / 16:53:40 UT Launch Site: Kennedy Space Center / Launch Complex 39B
Scientific Instruments:
Orbiter:
- solid state imager (SSI)
- near-infrared mapping spectrometer (NIMS)
- ultraviolet spectrometer / extreme ultraviolet spectrometer (UVS/EUV)
- photopolarimeter-radiometer (PPR)
- magnetometer (MAG)
- energetic particles detector (EPD)
- plasma subsystem (PLS)
- plasma wave subsystem (PWS)
- heavy ion counter (HIC)
- dust detector subsystem (DDS)
Atmospheric Entry Probe:
- atmospheric structure instrument
- neutral mass spectrometer
- helium abundance interferometer
- net-flux radiometer
- nephelometer
- lightning/radio-emission instrument
Results: Galileo, one of NASA's most ambitious deep space exploration projects, was the result of plans dating back to the early 1980s to deploy a Jupiter orbiter and probe. In its final configuration, the orbiter was a 4.6-meter tall spacecraft designed to operate for 22 months in Jovian orbit using 10 instruments/experiments to study the planet's atmosphere, satellites, and magnetosphere. Galileo, named after the Italian astronomer Galileo Galilei (1564–1642), carried a 337-kilogram probe designed to return data as it entered the Jovian atmosphere (by parachute) to identify atmospheric materials and conditions that cannot be detected from outside. Because of limitations of a Space Shuttle/IUS combination, NASA decided to use a complex multiple gravity assist scheme that required three flybys (two of Earth and one of Venus) on its way to Jupiter. The STS-34R crew released the spacecraft 6.5 hours after launch; an hour later, the two-stage IUS fired to send Galileo on its way.
Galileo flew past Venus at 05:58:48 UT on 10 February 1990 at a range of 16,106 kilometers during which it conducted an extensive survey of the planet (including imaging). Having gained 8,030 kilometers/hour in velocity, the spacecraft flew by Earth twice, the first time at 960 kilometers range at 20:34:34 UT on 8 December 1990 when it detected chemical signatures associated with lifeform activity in atmospheric trace elements on our home planet. The spacecraft also conducted lunar observations. A major problem occurred on 11 April 1991 when the high-gain antenna failed to fully deploy, thus eliminating the possibility of data transmission during its flyby of the asteroid 951 Gaspra. A low-gain antenna was instead used for the remainder of the mission, augmented by ingenious strategies including the use of data compression software that allowed a higher data throughput than was originally possible with the low-gain antenna. Becoming the first human-made object to fly past an asteroid, Galileo approached the minor planet Gaspra to a distance of 1,604 kilometers at 22:37 UT on 29 October 1991. The encounter provided much data including 150 images of the asteroid. Galileo then sped to its second encounter with the Earth–Moon system, with a flyby of Earth at 303.1 kilometers at 15:09:25 UT on 8 December 1992, adding 3.7 kilometers/second to its cumulative velocity. Galileo flew by a second asteroid, 243 Ida, at 16:51:59 UT on 28 August 1993 at a range of 2,410 kilometers, providing further data on minor planets. Later in July 1994, as it was speeding towards Jupiter, Galileo provided astronomers' only direct observations of Comet D/1993 F2 (Shoemaker-Levy 9) as its fragments impacted into the Jovian atmosphere.
Vega 1
Nation: USSR (102) Objective(s): Venus atmospheric entry and landing, Halley’s Comet flyby Spacecraft: 5VK (no. 901) = 5VS (Venus orbiter) + 5VP (Halley flyby + Venus lander) Spacecraft Mass: c. 4,840 kg Mission Design and Management: NPO imeni Lavochkina Launch Vehicle: Proton-K + Blok D-1 (Proton-K no. 329-01 + 11S824M no. 11L) Launch Date and Time: 15 December 1984 / 09:16:24 UT Launch Site: NIIP-5 / Site 200/39
Scientific Instruments:
Lander:
- meteorological complex to measure temperature and pressure
- VM-4 instrument to measure moisture content
- Sigma-3 gas chromatograph
- IFP aerosol x-ray fluorescence spectrometer
- ISAV-A optical aerosol analyzer
- ISAV-S ultraviolet spectrometer
- LSA laser aerosol meter
- Malakhit-M aerosol mass spectrometer (MS 1S1)
- BDRP-AM25 soil x-ray fluorescence spectrometer + drill
- GS-15STsV gamma-ray spectrometer
- PrOP-V penetrometer/soil ohmmeter
Balloon:
- temperature and pressure sensors
- vertical wind anemometer
- nephelometer
- light level/lighting detector
Bus:
- magnetometer (MISHA)
- PLAZMAG-1 plasma energy analyzer
- Tyunde-M energetic particle analyzer
- neutral gas mass spectrometer (ING)
- APV-V high-frequency plasma wave analyzer
- APV-N low-frequency plasma wave analyzer
- dust mass spectrometer (PUMA)
- SP-1 and SP-2 dust particle counters
- dust counter and mass analyzer (DUCMA)
- Foton dust particle recorder
- imaging system (TVS)
- infrared spectrometer (IKS)
- ultraviolet, visible, infrared imaging spectrometer (TKS)
Results: The twin-spacecraft Vega project, named after the combination of Venera and Gallei, the Russian words for "Venus" and "Halley," was perhaps the most ambitious deep space Soviet mission to date. The mission had three major goals: to place advanced lander modules on the surface of Venus, to deploy balloons (two each) in the Venusian atmosphere, and by using Venusian gravity, to fly the remaining buses past the Comet Halley. The entire mission was a cooperative effort between the Soviet Union (who provided the spacecraft and launch vehicle) with contributions from Austria, Bulgaria, Hungary, the German Democratic Republic (East Germany), Poland, Czechoslovakia, France (whose contribution was significant), and the Federal Republic of Germany (West Germany). In addition, one instrument, a comet dust (flux) analyzer, was provided by an American cosmic ray physicist, John A. Simpson (1916–2000), at the University of Chicago. This instrument turned out to be the only American instrument that directly studied Halley's comet during its 1986 encounter.
While the landers were similar to ones used before for exploring Venus, the balloon gondolas were completely new Soviet-made vehicles that carried U.S.-French nephelometers to measure aerosol distribution in the atmosphere. The cometary flyby probes, which contained a 120-kilogram scientific package, were protected against high-velocity impacts from dust particles. After a successful flight to Venus, Vega 1 released its 1,500-kilogram descent module on 9 June 1985, two days before atmospheric entry. As the lander descended, at 61 kilometers altitude, it released the first helium-inflated plastic balloon with a hanging gondola underneath it. Mass was around 20.8 kilograms. As the balloon drifted through the Venusian atmosphere (controlled partly by ballast), it transmitted important data on the atmosphere back to a network of tracking antennas on Earth. Balloon 1 survived for 46.5 hours, eventually succumbing due to battery failure, having traversed about 11,600 kilometers. The lander set down safely on the ground at 03:02:54 UT on 11 June 1985 at 8.1° N / 176.7° longitude on the night side of Venus in the Mermaid Plain north of Aphrodite and transmitted from the surface for 56 minutes. Temperature and pressure at the landing site were 467°C and 93.88 atmospheres, respectively. The soil sample drill failed to complete its soil analysis, having spuriously deployed about 15 minutes before reaching the surface, but the mass spectrometer returned important data.
The Vega 1 bus flew by Venus at a range of 39,000 kilometers and then headed for its encounter with Halley. After course corrections on 25 June 1985 and 10 February 1986, the spacecraft began its formal studies of the comet on 4 March when it was 14 million kilometers from its target. During the 3-hour encounter on 6 March 1986, the spacecraft approached to within 8,889 kilometers (at 07:20:06 UT) of Halley. Vega 1 took more than 500 pictures via different filters as it flew through the gas cloud around the coma. Although the spacecraft was battered by dust, none of the instruments were disabled during the encounter. Vega 1 collected a wealth of information on Halley including data on its nucleus, its dust production rate, its chemical composition, and its rotational rate. After subsequent imaging sessions on 7 and 8 March 1986, Vega 1 headed out to heliocentric orbit where it continued to transmit data from at least some of its instruments until last contact on 30 January 1987.
Vega 2
Nation: USSR (103) Objective(s): Venus atmospheric entry, Halley’s Comet flyby Spacecraft: 5VK (no. 902) = 5VS (Venus orbiter) + 5VP (Halley flyby + Venus lander) Spacecraft Mass: 4,840 kg Mission Design and Management: NPO imeni Lavochkina Launch Vehicle: Proton-K + Blok D-1 (8K82K no. 325-02 + 11S824M no. 12L) Launch Date and Time: 21 December 1984 / 09:13:52 UT Launch Site: NIIP-5 / Site 200/40
Scientific Instruments:
Lander:
- meteorological complex to measure temperature and pressure
- VM-4 instrument to measure moisture content
- Sigma-3 gas chromatograph
- IFP aerosol x-ray fluorescence spectrometer
- ISAV-A optical aerosol analyzer
- ISAV-S ultraviolet spectrometer
- LSA laser aerosol meter
- Malakhit-M aerosol mass spectrometer (MS 1S1)
- BDRP-AM25 soil x-ray fluorescence spectrometer + drill
- GS-15STsV gamma-ray spectrometer
- PrOP-V penetrometer/soil ohmmeter
Balloon:
- temperature and pressure sensors
- vertical wind anemometer
- nephelometer
- light level/lighting detector
Bus:
- magnetometer (MISHA)
- PLAZMAG-1 plasma energy analyzer
- Tyunde-M energetic particle analyzer
- neutral gas mass spectrometer (ING)
- APV-V high-frequency plasma wave analyzer
- APV-N low-frequency plasma wave analyzer
- dust mass spectrometer (PUMA)
- SP-1 and SP-2 dust particle counters
- dust counter and mass analyzer (DUCMA)
- Foton dust particle recorder
- imaging system (TVS)
- infrared spectrometer (IKS)
- ultraviolet, visible, infrared imaging spectrometer (TKS)
Results: Vega 2 was the sister spacecraft to Vega 1, and essentially performed a near-identical mission to its twin. The main lander probe set down without problems at 03:00:50 UT on 15 June 1985 in the northern region of Aphrodite, about 1,500 kilometers south-east of Vega. Landing coordinates were 7.2° S / 179.4° longitude. Temperature and pressure were recorded as 462°C and 87.11 atmospheres, respectively. The spacecraft transmitted from the surface for 57 minutes. Unlike its twin, the Vega 2 lander was able to collect and investigate a soil sample; the experiment identified an anorthosite-troctolite rock, rarely found on Earth, but present in the lunar highlands. According to the lander's data, the area was probably the oldest explored by any Venera vehicle. The mass spectrometer did not return any data. The balloon, released upon entry into the atmosphere, flew through the Venusian atmosphere, collecting data like its twin and survived for 46.5 hours of data transmission, traveling a slightly longer distance than its compatriot from Vega 1. Neither balloon on Vega 1 nor Vega 2 detected any lightning in the Venusian atmosphere.
After releasing its lander, the flyby probe continued on its flight to Comet Halley. The spacecraft initiated its encounter on 7 March 1986 by taking 100 photos of the comet from a distance of 14 million kilometers. Vega 2's closest approach (8,030 kilometers) to Halley was at 07:20 UT two days later when the spacecraft was traveling at a velocity of 76.8 kilometers/second (slightly lower than Vega 1's 79.2 kilometers/second). During the encounter, Vega 2 took 700 images of the comet of much better resolution than those from its twin, partly due to the presence of less dust outside of the coma during this transit, although many of the images were overexposed due to a failure in the primary pointing software. Ironically, Vega 2 sustained an 80% power loss during the encounter (as compared to Vega 1's 40%). Seven instruments between the two spacecraft were partially damaged, although no instrument on both were incapacitated. After further imaging sessions on 10 and 11 March 1986, Vega 2 finished its primary mission and headed out into heliocentric orbit. Like Vega 1, Vega 2 continued "a series of scientific investigations" until last contact on 24 March 1987.