Suisei (すいせい, lit. "Comet"), 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).
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![]() Spacecraft Suisei | |
Names | Planet-A (before launch) |
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Operator | ISAS (now part of Japanese Aerospace Exploration Agency) |
COSPAR ID | 1985-073A ![]() |
SATCAT no. | 15967 |
Website | Suisei |
Mission duration | 5 years and 5 months (launch to fuel depletion) |
Spacecraft properties | |
Launch mass | 139.5 kg (308 lb) |
Start of mission | |
Launch date | 23:33, August 18, 1985 (UTC) (1985-08-18T23:33Z) |
Rocket | M-3SII |
Launch site | Uchinoura Space Center |
End of mission | |
Disposal | Ran out of fuel by February 22, 1991 |
Orbital parameters | |
Reference system | Heliocentric |
Sun orbiter | |
Flyby of Comet Halley | |
Closest approach | March 8, 1986 |
Distance | 151,000 km (94,000 mi) |
Flyby of Earth | |
Closest approach | August 20, 1992 |
Distance | ~900,000 km (560,000 mi) |
It constituted a part of the Halley Armada together with Sakigake, the Soviet 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.
Suisei was identical in construction and shape to Sakigake, but carried a different payload: a CCD 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.
Suisei was launched on August 18, 1985 by M-3SII launch vehicle from Kagoshima Space Center on M-3SII-2 mission. 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.
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.
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 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.
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.
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Japanese space program | |||||||||||||
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Astronomical observation |
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Engineering tests |
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Human spaceflight |
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Private miniaturized satellites |
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Reconnaissance |
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← 1984 · Orbital launches in 1985 · 1986 → | |
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Sakigake | Kosmos 1616 | Kosmos 1617 · Kosmos 1618 · Kosmos 1619 · Kosmos 1620 · Kosmos 1621 · Kosmos 1622 | Molniya-3 No.36 | Kosmos 1623 | Kosmos 1624 | Gorizont No.21L | Kosmos 1625 | Kosmos 1626 | STS-51-C (USA-8) | Kosmos 1627 | Kosmos 1628 | Meteor-2 No.13 | USA-9 | Arabsat-1A · Brasilsat A1 | Kosmos 1629 | Kosmos 1630 | Kosmos 1631 | Kosmos 1632 | Kosmos 1633 | Geosat | Kosmos 1634 | Kosmos 1635 · Kosmos 1636 · Kosmos 1637 · Kosmos 1638 · Kosmos 1639 · Kosmos 1640 · Kosmos 1641 · Kosmos 1642 | Ekran No.28L | Intelsat VA F-10 | Kosmos 1643 | Kosmos 1644 | STS-51-D (Anik C1 · Leasat 3) | Unnamed | Kosmos 1645 | Kosmos 1646 | Kosmos 1647 | Kosmos 1648 | Prognoz 10 | STS-51-B (Nusat) | GStar-1 · Telecom 1B | Kosmos 1649 | Kosmos 1650 · Kosmos 1651 · Kosmos 1652 | Kosmos 1653 | Kosmos 1654 | Molniya-3 No.39 | Kosmos 1655 | Kosmos 1656 | Soyuz T-13 | Kosmos 1657 | Kosmos 1658 | Kosmos 1659 | Kosmos 1660 | STS-51-G (Morelos 1 · Arabsat-1B · Telstar 3D · SPARTAN-101) | Kosmos 1661 | Kosmos 1662 | Progress 24 | Kosmos 1663 | Unnamed | Kosmos 1664 | Intelsat VA F-11 | Giotto | Kosmos 1665 | Kosmos 1666 | Kosmos 1667 | Kosmos 1668 | Molniya-3 No.37 | Kosmos 1669 | STS-51-F (PDP) | Kosmos 1670 | Kosmos 1671 | Transit-O 24 · Transit-O 30 | Kosmos 1672 · Kosmos 1672 | Kosmos 1673 | Kosmos 1674 | Gran' No.26L | Kosmos 1675 | Kosmos 1676 | Suisei | Molniya-1 No.61 | Kosmos 1677 | STS-51-I (Aussat A1 · ASC-1 · Leasat 4) | Unnamed | Kosmos 1678 | Kosmos 1679 | Kosmos 1680 | Kosmos 1681 | ECS-3 · Spacenet 3 | Soyuz T-14 | Kosmos 1682 | Kosmos 1683 | Kosmos 1684 | Kosmos 1685 | Kosmos 1686 | Intelsat VA F-12 | Kosmos 1687 | Kosmos 1688 | Kosmos 1689 | Molniya-3 No.38 | STS-51-J (USA-11 · USA-12) | USA-10 | Kosmos 1690 · Kosmos 1695 · Kosmos 1692 · Kosmos 1693 · Kosmos 1694 · Kosmos 1691 | Kosmos 1696 | Fanhui Shi Weixing 8 | Kosmos 1697 | Kosmos 1698 | Molniya-1 No.73 | Unnamed | Meteor-3 No.2 | Kosmos 1699 | Kosmos 1700 | Molniya-1 No.56 | STS-61-A (GLOMR) | Kosmos 1701 | Kosmos 1702 | Gran' No.28L | Kosmos 1703 | STS-61-B (Morelos 2 · Aussat A2 · Satcom K2 · OEX · EASE/ACCESS) | Kosmos 1704 | Kosmos 1705 | Kosmos 1706 | Kosmos 1707 | USA-13 · USA-14 | Kosmos 1708 | Kosmos 1709 | Molniya-3 No.40 | Kosmos 1710 · Kosmos 1711 · Kosmos 1712 | Meteor-2 No.14 | Kosmos 1713 | Kosmos 1714 | |
Payloads are separated by bullets ( · ), launches by pipes ( | ). Crewed flights are indicated in underline. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in (brackets). |