Hiten (MUSES-A)
Hiten (MUSES-A) — Japan's first mission to the Moon, launched by the Institute of Space and Astronautical Science on 24 January 1990. From a long, looping Earth orbit it flew past the Moon again and again, released a small orbiter, Hagoromo, at its first pass, and in 1991 became the first deep-space probe to aerobrake, dipping into Earth's upper atmosphere to slow down. It entered orbit around the Moon on 15 February 1992 and struck it on 10 April 1993. (Its orbit is drawn to a published size; its orientation and position on it are representative.)
Key facts
Mission & specifications
Mission
- Operator
- ISAS (Japan)
- Launched
- January 24, 1990
- Status
- Completed
Trajectory
- Distance from the Sun
- 0.996 AU
- Computed from the cached position
- Distance from Earth
- 1,461,182 km
- Computed from cached positions
- Distance from Venus
- 0.276 AU
- Computed from cached positions
Mission
Hiten, called MUSES-A before launch, was Japan's first mission to the Moon, an engineering test spacecraft built by the Institute of Space and Astronautical Science. It was launched on a Mu-3SII rocket from Kagoshima on 24 January 1990. The rocket delivered it about 50 m/s too slowly, so its first apogee was about 290,000 km instead of the planned 476,000 km, and its controllers had to redesign the flight. It flew a long, looping Earth orbit that swung past the Moon again and again. At the first pass, on 18 March 1990 (UTC), it released Hagoromo, a small orbiter of about 12 kg carrying its own braking rocket. The rocket was seen to fire, but Hagoromo's transmitter had already failed, so whether it entered lunar orbit was never confirmed. In March 1991 Hiten twice dipped to about 120 km above Earth, the first time a deep-space probe had used the drag of an atmosphere to change its orbit. Later that year it looped through the Earth–Moon L4 and L5 points looking for trapped dust and found no clear increase. On 15 February 1992 it fired its engine at its closest approach, 422 km from the Moon, and entered lunar orbit, using most of its remaining fuel. It struck the Moon on 10 April 1993, near the craters Stevinus and Furnerius. Two published estimates place the impact at 34.0°S, 55.3°E or 34.3°S, 55.6°E.
- 1990Hiten launches toward the Moon on a Mu-3SII rocketLaunch
From Kagoshima; the rocket leaves it about 50 m/s short of its planned speed.
Hagoromo's braking rocket is seen to fire, but its transmitter had already failed.
- 1991The first aerobraking by a deep-space probeMilestone
125.5 km above Earth, the drag of the upper atmosphere lowers its orbit.
- 1991Captured by the Moon without an engine burnMilestone
A temporary capture on a low-energy route, the first use of one.
- 1992Into lunar orbitArrival
Fired at its closest approach, 422 km from the Moon, using most of its remaining fuel.
- 1993Hiten strikes the MoonMission end
Near the craters Stevinus and Furnerius.
Images
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