Suisei probe
Encyclopedia
Suisei originally known as Planet-A, was an unmanned space probe
developed by the Institute of Space and Astronautical Science
(now part of the Japanese Aerospace Exploration Agency, or JAXA).
It constituted a part of the Halley Armada
together with Sakigake
, the Soviet
/French
Vega
probes, the ESA
Giotto
and the NASA International Cometary Explorer
, to explore Halley's Comet during its 1986 sojourn through the inner solar system.
UV imaging system and a solar wind
instrument
.
The main objective of the mission was to take UV images of the hydrogen corona
for about 30 days before and after Comet Halley's descending crossing of the ecliptic plane
. Solar wind parameters were measured for a much longer time period. The spacecraft
is spin-stabilized at two different rates (5 and 0.2 rpm). Hydrazine
thrusters are used for attitude and velocity control; star
and sun sensors are for attitude control; and a mechanically despun off-set parabolic dish is used for long range communication
.
launch vehicle from Kagoshima Space Center. It was sent on an intercept course with Comet Halley, after which it would remain in a heliocentric orbit
for later use as long as it was viable.
The spacecraft encountered Comet Halley at 151,000 km on sunward side during March 8, 1986, suffering only 2 dust impacts.
gravity assist swingby on August 20, 1992, although the craft was then lost behind the Sun for the summer
.
The hydrazine
fuel was depleted on February 22, 1991. Preliminary tracking indicated a 900,000 km flyby had been achieved.
, but due to depletion of the hydrazine, this, as well as plans to fly within several million kilometers of Comet 55P/Tempel-Tuttle
on February 28, 1998, were cancelled.
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
developed by the Institute of Space and Astronautical Science
Institute of Space and Astronautical Science
is a Japanese national research organization of astrophysics using rockets, astronomical satellites and interplanetary probes. It is a division of Japan Aerospace Exploration Agency .- History :...
(now part of the Japanese Aerospace Exploration Agency, or JAXA).
It constituted a part of the Halley Armada
Halley Armada
The Halley Armada is the generally accepted and popularly used name of five space probes sent to examine Halley's Comet during its 1986 sojourn through the inner solar system, connected with apparition "1P/1982 U1"...
together with Sakigake
Sakigake
Sakigake , pre-launch codename MS-T5, was Japan's first interplanetary spacecraft, and the first deep space probe to be launched by any country other than the USA or the Soviet Union...
, the Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
/French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
Vega
Vega program
The Vega program was a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland,...
probes, the ESA
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
Giotto
Giotto mission
Giotto was a European robotic spacecraft mission from the European Space Agency, intended to fly by and study Halley's Comet. On 13 March 1986, the mission succeeded in approaching Halley's nucleus at a distance of 596 kilometers....
and the NASA International Cometary Explorer
International Cometary Explorer
The International Cometary Explorer spacecraft was originally known as International Sun/Earth Explorer 3 satellite, launched August 12, 1978. It was part of the ISEE international cooperative program between NASA and ESRO/ESA to study the interaction between the Earth's magnetic field and the...
, to explore Halley's Comet during its 1986 sojourn through the inner solar system.
Spacecraft
Suisei was identical in construction and shape to Sakigake, but carried a different payload: a CCDCharge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
UV imaging system and a solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...
instrument
Measuring instrument
In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item...
.
The main objective of the mission was to take UV images of the hydrogen corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...
for about 30 days before and after Comet Halley's descending crossing of the ecliptic plane
Plane of the ecliptic
The plane of the ecliptic is the plane of the Earth's orbit around the Sun. It is the primary reference plane when describing the position of bodies in the Solar System, with celestial latitude being measured relative to the ecliptic plane. In the course of a year, the Sun's apparent path through...
. Solar wind parameters were measured for a much longer time period. The spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
is spin-stabilized at two different rates (5 and 0.2 rpm). Hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
thrusters are used for attitude and velocity control; star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
and sun sensors are for attitude control; and a mechanically despun off-set parabolic dish is used for long range communication
Communication
Communication is the activity of conveying meaningful information. Communication requires a sender, a message, and an intended recipient, although the receiver need not be present or aware of the sender's intent to communicate at the time of communication; thus communication can occur across vast...
.
Launch
Suisei was launched on August 18, 1985 by M-3SII-2Mu (rocket)
The Mu, also known as M, was a series of Japanese solid-fuelled carrier rockets, which were launched from Uchinoura between 1966 and 2006...
launch vehicle from Kagoshima Space Center. It was sent on an intercept course with Comet Halley, after which it would remain in a heliocentric orbit
Heliocentric orbit
A heliocentric orbit is an orbit around the Sun. All planets, comets, and asteroids in our Solar System are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet...
for later use as long as it was viable.
Halley encounter
Suisei began UV observations in November 1985, generating up to 6 images/day.The spacecraft encountered Comet Halley at 151,000 km on sunward side during March 8, 1986, suffering only 2 dust impacts.
Earth flyby
Fifteen burns of Suisei's 3 N motors during the period of April 5–10, 1987, yielded a 65 m/s velocity increase for a 60,000 km EarthEarth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
gravity assist swingby on August 20, 1992, although the craft was then lost behind the Sun for the summer
Summer
Summer is the warmest of the four temperate seasons, between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice...
.
The hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
fuel was depleted on February 22, 1991. Preliminary tracking indicated a 900,000 km flyby had been achieved.
Other planned encounters
ISAS had decided during 1987 to guide Suisei to a November 24, 1998, encounter with 21P/Giacobini-Zinner21P/Giacobini-Zinner
Comet Giacobini–Zinner is a periodic comet in our solar system.It was discovered by Michel Giacobini from , who observed the comet in the constellation of Aquarius on December 20, 1900...
, but due to depletion of the hydrazine, this, as well as plans to fly within several million kilometers of Comet 55P/Tempel-Tuttle
55P/Tempel-Tuttle
55P/Tempel–Tuttle is a comet that was independently discovered by Ernst Tempel on December 19, 1865 and by Horace Parnell Tuttle on January 6, 1866.It is the parent body of the Leonid meteor shower...
on February 28, 1998, were cancelled.