Suisei (probe)
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, originally known as Planet-A, was an uncrewed
space probe Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which th ...
developed by the
Institute of Space and Astronautical Science , or ISAS, is a Japanese national research organization of astrophysics using rockets, astronomical satellites and interplanetary probes which played a major role in Japan's space development. Established as part of the University of Tokyo ...
(now part of the
Japanese Aerospace Exploration Agency The is the Japanese national air and space agency. Through the merger of three previously independent organizations, JAXA was formed on 1 October 2003. JAXA is responsible for research, technology development and launch of satellites into or ...
, or JAXA). It constituted a part of the
Halley Armada The Halley Armada is the name of a series of space probes, five of which were successful, sent to examine Halley's Comet during its 1986 sojourn through the inner Solar System, connected with apparition "1P/1982 U1". The armada included one prob ...
together with ''
Sakigake , known before launch as MS-T5, was Japan's first interplanetary spaceflight, interplanetary spacecraft and the first deep space probe to be launched by any country other than the US or the Soviet Union. It aimed to demonstrate the performan ...
'', the
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
Vega Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, and ...
probes, the
ESA The European Space Agency (ESA) is a 23-member international organization devoted to space exploration. With its headquarters in Paris and a staff of around 2,547 people globally as of 2023, ESA was founded in 1975 in the context of European ...
''Giotto'' and the
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
International Cometary Explorer The International Cometary Explorer (ICE) spacecraft, designed and launched as the International Sun-Earth Explorer-3 (ISEE-3) satellite, was launched on 12 August 1978 into a heliocentric orbit. It was one of three spacecraft, along with the m ...
, to explore
Halley's Comet Halley's Comet is the only known List of periodic comets, short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions (25 of 30) occurring after ...
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
CCD CCD may refer to: Science and technology * Charge-coupled device, an electronic light sensor used in various devices including digital cameras * .ccd, the filename extension for CloneCD's CD image file * Carbonate compensation depth, a property ...
UV imaging system and a
solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...
instrument. The main objective of the mission was to take UV images of the hydrogen
corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus or disease responsible for the COVID-19 ...
for about 30 days before and after Comet Halley's descending crossing of the
ecliptic plane The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. From the perspec ...
. Solar wind parameters were measured for a much longer time period. The
spacecraft A spacecraft is a vehicle that is designed spaceflight, to fly and operate in outer space. Spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth observation, Weather s ...
is spin-stabilized at two different rates (5 and 0.2 rpm).
Hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...
thrusters are used for attitude and velocity control; star and
Sun sensor A Sun sensor is a navigational instrument used by spacecraft to detect the position of the Sun. Sun sensors are used for Spacecraft attitude control, attitude control, solar array pointing, gyroscope, gyro updating, and safe mode (spacecraft), fai ...
s are for attitude control; and a mechanically despun off-set
parabolic dish A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated ...
is used for long range
communication Communication is commonly defined as the transmission of information. Its precise definition is disputed and there are disagreements about whether Intention, unintentional or failed transmissions are included and whether communication not onl ...
.


Launch

''Suisei'' was launched on August 18, 1985 by
M-3SII The Mu, also known as M, was a series of Japanese Solid-fuel rocket, solid-fueled carrier rockets, which were launched from Uchinoura Space Center, Uchinoura between 1966 and 2006. Originally developed by Japan's Institute of Space and Astronauti ...
launch vehicle from
Kagoshima Space Center The is a space launch facility in the Japanese town of Kimotsuki, Kagoshima, Kimotsuki, Kagoshima Prefecture. Before the establishment of the Japan Aerospace Exploration Agency, JAXA space agency in 2003, it was simply called the (KSC). All o ...
on M-3SII-2 mission. It was sent on an intercept course with Comet Halley, after which it would remain in a
heliocentric orbit A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun ...
for later use as long as it was viable.


Halley encounter

''Suisei'' began UV
observations Observation in the natural sciences is an act or instance of noticing or perceiving and the acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perceptio ...
in November 1985, generating up to six images/day. The spacecraft encountered Comet Halley at 151,000 km on sunward side during March 8, 1986, suffering only two dust impacts. Suisei carried two instruments designed to study the growth and the decay of the cometary object's hydrogen corona, and the interaction of the solar wind with the cometary ionosphere.


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
Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...
swingby on August 20, 1992, although the craft was then lost behind the Sun for the
summer Summer or summertime is the hottest and brightest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, daylight hours are the longest and darkness hours are the shortest, with day ...
. The
hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...
fuel was depleted on February 22, 1991. Preliminary tracking indicated a 900,000-km flyby of Earth had been achieved.


Other planned encounters

ISAS had decided during 1987 to guide ''Suisei'' to a November 24, 1998, encounter with 21P/Giacobini-Zinner, 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.


References


External links


''Suisei'' Mission Profile
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NASA's Solar System Exploration
{{DEFAULTSORT:Suisei (Probe) Japanese space probes Missions to Halley's Comet Satellites orbiting the Sun 1985 in spaceflight Derelict space probes Spacecraft launched in 1985 Japanese inventions