Fobos 2
Nation: USSR (105) Objective(s): Mars flyby, Phobos encounter Spacecraft: 1F (no. 102) Spacecraft Mass: 6,220 kg Mission Design and Management: NPO imeni Lavochkina Launch Vehicle: Proton-K + Blok D-2 (8K82K no. 356-01 + 11S824F no. 1L) Launch Date and Time: 12 July 1988 / 17:01:43 UT Launch Site: NIIP-5 / Site 200/40
Scientific Instruments:
Orbiter:
- Lima-D laser mass spectrometer analyzer
- Dion secondary ion mass analyzer
- radar system (without Plazma ionosphere study instrument, only on Fobos 1) (RLK)
- videospectrometric system (VSK)
- KRFM-ISM infrared spectrometer
- Termoskan infrared spectrometer
- GS-14 STsF gamma-emission spectrometer
- Ogyust optical radiation spectrometer (ISO)
- scanning energy-mass spectrometer (ASPERA)
- plasma spectrometer (MPK)
- Ester electron spectrometer
- plasma wave analyzer (APV-F / PWS)
- flux gate magnetometer (FGMM)
- magnetometer (MAGMA)
- x-ray photometer (RF-15)
- ultrasound spectrometer (SUFR)
- gamma-ray burst spectrometer (VGS)
- Lilas gamma-ray burst spectrometer
- solar photometer (IFIR)
- Termoskop
- Taus proton and alpha-particle spectrometer
- Harp ion and electron spectrometer
- Sovikoms energy, mass, and charge spectrometer
- Sled charged-particle spectrometer
DAS:
- Alfa x-ray and alpha-particle backscattering spectrometer
- Stenopee (Libratsiya) sun sensor to measure librations
- 2 cameras
- vibration measurement instrument (VIK) + temperature sensor
- transponder
PrOP-FP:
- penetrometer with ground sampler
- accelerometers
- x-ray fluorescence spectrometer
- magnetometer (MFP)
- kappameter
- gravimeter
- surface temperature sensors
- instrument to measure surface electrical resistance
- instrument to measure position tilt
Results: Fobos 2 had the same mission as its twin Fobos 1, to orbit Mars and fly past Phobos (on 13 June 1989) but had an additional payload, a small 43-kilogram instrumented "hopper" known as PrOP-FP that would make 20-meter jumps across the surface of Phobos for about 4 hours. The orbiter also had a slightly different instrument complement—it did not carry the IPNM, Plazma, and Terek instruments carried on Fobos 1. PrOP-FP (Device to Evaluate Mobility—Phobos) had its own power supply system, radio transmitter, and a suite of scientific instruments. This "rover" was designed to perform hops ranging from 10 to 40 meters and take data measurements after each hop. Despite some onboard anomalies, Fobos 2 carried out two en route course corrections on 21 July 1988 and 23 January 1989. One of the two radio transmitters failed, while its Buk computer was acting erratically due to faulty capacitors in the computer's power supply, a fact that was known before launch.
At 12:55 UT on 29 January 1989, the spacecraft fired its engine to enter orbit around Mars. Initial orbital parameters were 819 × 81,214 kilometers at 1.5° inclination. In the initial months in orbit around Mars, the spacecraft conducted substantive investigations of the Red Planet and also photographed areas of its surface. During this period, controllers implemented four further orbital corrections in order to put its trajectory on an encounter course with Phobos. The spacecraft also jettisoned its Fregat upper stage (which had fired its engine to enter Mars orbit). Fobos 2 took high resolution photos of the moon on 23 February (at 860 kilometers range), 28 February (320 kilometers), and 25 March 1989 (191 kilometers), covering about 80% of its surface. Release of its lander was scheduled for 4–5 April 1989, but on 27 March during a regularly planned communications session at 15:58 UT, there was no word from the spacecraft. A weak signal was received between 17:51 and 18:03 UT, but there was no telemetry information. The nature of the signal indicated that the spacecraft had lost all orientation and was spinning. Future attempts to regain communication were unsuccessful and the mission was declared lost on 14 April 1989. The most probable cause was failure of the power supply for the Buk computer, something that had actually happened earlier in the mission (on 21 January 1989). On this occasion, controllers failed to revive the vehicle. Roald Sagdeev (1932– ), the director of the Institute of Space Research noted in the journal Priroda (Nature) in mid-1989 that "I think we should seek the cause of the failure in the very organization of the project, in its planning" adding that "the relationships between the customer [the science community] and contractor [Lavochkin] … are clearly abnormal."
Galileo's atmospheric entry probe, based on the design of the large probe of the Pioneer Venus multiprobe, was finally released on 13 July 1995 when the spacecraft was still 80 million kilometers from Jupiter. The probe hit the atmosphere at 6.5° N / 4.4° W at 22:04:44 UT on 7 December 1995, traveling at a relative velocity of 48 kilometers/hour, and returned valuable data for 58 minutes as it plunged into the Jovian cauldron. The entry probe endured a maximum deceleration of 228 g's about a minute after entry when temperatures scaled up to 16,000°C. The probe's transmitter failed 61.4 minutes after entry when the spacecraft was 180 kilometers below its entry ceiling, evidently due to the enormous pressure (22.7 atmospheres). Data, originally transmitted to its parent and then later transmitted back to Earth, indicated an intense radiation belt 50,000 kilometers above Jupiter's clouds, few organic compounds, and winds as high as 640 meters/second. The entry probe also found less lightning, less water vapor, and half the helium than had been expected in the upper atmosphere.
The Galileo orbiter, meanwhile, fired its engine at 00:27 UT on 8 December, becoming Jupiter's first human-made satellite. Its orbital period was 198 days. Soon after, Galileo began its planned 11 tours over 22 months exploring the planet and its moons, including flybys of Ganymede (for the first time on 27 June 1996) and Europa (on 6 November 1997). Having fulfilled its original goals, NASA implemented a two-year extension to 31 December 1999 with the Galileo Europa Mission (GEM) during which the spacecraft conducted numerous flybys of Jupiter's moons, each encounter yielding a wealth of scientific data. These included flybys of Europa nine times (eight between December 1997 and February 1999 and once in January 2000), Callisto four times (between May 1999 and September 1999), and Io three times (in October 1999, November 1999, and February 2000). On the last flyby of Io, Galileo flew only 198 kilometers from the surface of Io sending back the highest resolution photos yet of the volcanically active moon.
On 8 March 2000, NASA announced plans to extend Galileo's mission again, with a new phase beginning October 2000 called the Galileo Millennium Mission. The idea was to coordinate investigations of Jupiter and its environs—particular the interaction of the solar wind with the planet's magnetosphere—with the Cassini spacecraft (on its way to Saturn) that was expected to fly past Jupiter in December 2000. This second extension was largely possible due to the extreme accuracy of navigation during the prior phases of the mission that had saved a significant amount of maneuvering propellant. The RTGs on board the spacecraft were still delivering about 450 W in 2000, although power capacity was declining at a rate of about 7 W per year. Under the Millennium Mission, Galileo flew by Ganymede, the largest moon in the solar system, on 20 May at a range of 809 kilometers and made its final flyby (also of Ganymede) on 28 December 2000 at a range of 2,337 kilometers. In January 2001, both Galileo and Cassini together encountered the magnetosphere bow shock within a half hour of each other.
As the mission entered its final phase, mission scientists arranged for three final flybys of Io, primarily to obtain more data on the moon's magnetic field and heat generation that drives its volcanism. A final flyby of Callisto (in May 2001) resulted in some very high-resolution photographs and led to the Io encounters in August and October 2001 and in January 2002, the last one at a staggering 101.5 kilometers range, the closest it had gotten to any moon in its entire mission. This close encounter increased Galileo's orbit such that it could be easily commanded in the future to terminate its mission in Jupiter's atmosphere. A flyby of Amalthea in November 2002 provided key information on the moon's density and preceded its closest flyby of Jupiter itself. Beginning March 2003, Galileo was contacted once a week only to verify its status. Many years of operation in the Jovian system had exposed the spacecraft to intense radiation, taking a toll on many systems and instruments. Because Galileo had not been sterilized, to prevent contamination, it was decided to have the vehicle burn up in the Jovian atmosphere instead of risking impact on a moon such as Europa.
Having completed its 35th orbit around Jupiter and after accompanying the planet for three-quarters of a circuit around the Sun, Galileo flew into the atmosphere at a velocity of 48.2 kilometers/second, just south of equator, on 21 September 2003 at 18:57 UT. In its nearly eight-year mission around Jupiter, Galileo had returned an unprecedented amount of data on the planet and its environs. For example, Galileo discovered far less lightning activity (about 10% of that found in an equal area on Earth) than anticipated, helium abundance in Jupiter very nearly the same as in the Sun (24% compared to 25%), extensive resurfacing of Io's surface due to continuing volcanic activity since the Voyagers flew by in 1979, and evidence for liquid water ocean under Europa's icy surface (with indications of similar liquid saltwater layers under the surfaces of Ganymede and Callisto). Jupiter's ring system was found to be made of dust from impacts on the four small inner moons. Galileo also discovered materials linked to organic compounds (clay-like minerals known as phyllosilicates) on the icy crust of Europa, perhaps produced by collisions with an asteroid or a comet. The spacecraft also identified the first internal magnetic field of a moon (Ganymede) that produces a "minimagnetosphere" within Jupiter's larger magnetosphere. By March 2000, the spacecraft had returned about 14,000 images back to Earth.
Hiten and Hagoromo
Nation: Japan (3) Objective(s): lunar flyby and lunar orbit Spacecraft: MUSES-A and Hagoromo subsatellite Spacecraft Mass: 185 kg (MUSES-A), 12 kg (Hagoromo) Mission Design and Management: ISAS Launch Vehicle: Mu-3S-II (no. 5) Launch Date and Time: 24 January 1990 / 11:46:00 UT Launch Site: Kagoshima / Launch Complex M1
Scientific Instruments:
Hiten:
- cosmic dust detector (MDC)
Results: This two-module Japanese spacecraft was designed to fly past the Moon and release an orbiter. It was the first Japanese lunar mission and also the first robotic lunar probe since the flight of the Soviet Luna 24 in 1976. MUSES-A (for Mu-launched Space Engineering Satellite), named Hiten ("musical angel") after launch, was put into a highly elliptical orbit around Earth that intersected with the Moon's orbit. Due to a problem with the orbital injection burn, the probe's orbital apogee was 290,000 kilometers, much less than the hoped for 476,000 kilometers, but after a number of subsequent maneuvers, Hiten reached its originally planned nominal orbit. At 19:37 UT on 18 March, during its first flyby of the Moon, Hiten released into lunar orbit, a small 12-kilogram "grandchild" satellite named Hagoromo. Hagoromo did not carry any science instruments and was designed to only transmit telemetry and diagnostic data back to Earth, but it made Japan the first nation besides the Soviet Union and the United States to put a spacecraft into lunar orbit.
Image
Hagoromo's initial orbital parameters were 20,000 × 7,400 kilometers. Although the maneuver successfully demonstrated the use of the swingby technique to enter lunar orbit, communications with Hagoromo had already been lost shortly before release on 21 February when its S-band transmitter failed. Hiten, meanwhile, passed by the Moon at 20:04:09 UT on 18 March at a distance of 16,472.4 kilometers and continued on its trajectory, simulating the orbital path of the proposed Geotail spacecraft. By 4 March 1991, Hiten had carried out seven more lunar flybys and began a phase of aerobraking into Earth's atmosphere—a feat it carried out for the first time by any spacecraft on 19 March (at 00:43 UT) at an altitude of 125.5 kilometers, which lowered Hiten's relative velocity by 1.712 meters/second and its orbital apogee by 8,665 kilometers. A second aerobraking over Earth occurred at 11:36 UT on 30 March at 120 kilometers altitude, reducing velocity by 2.8 kilometers/second and apogee by another 14,000 kilometers.