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ISAS Planned Missions

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The ISAS has three missions planned between now and 2010. They include:

  • Lunar-A (maybe 2006) - an orbiter and penetrator mission to the moon
  • SELENE (2007) - another orbiter to the moon
  • Planet-C (2008) - Venus orbiter


Lunar-A is a probe that Japan will send to the moon to photograph the surface, monitor moonquakes, measure temperature, and study the internal structure. In order to do this, it will carry a mapping camera and two surface penetrators; these penetrators have seismometers and sensors to measure heat flow. The seismometers will monitor moonquakes over one year; the moonquake data will be used to learn about the internal structure of the moon, and it will hopefully determine composition, size, and nature of the core. The thermal sensors will help to determine the evolution of the moon.

Lunar-AThis was originally planned to have been launched on August 28, 1999; however, it was rescheduled for August or September of 2004, because one of the penetrators failed a 300 m (0.2 mile) drop test, so it is being redesigned. It has since been delayed again for technical and financial reasons, and it is being re-evaluated. It will launch no sooner than 2006.

Assuming Lunar-A is launched, it will go into an Earth orbit; it will then move into an orbit around both Earth and the moon. Once it has completed 4.5 of these orbits, it will swing into a very wide orbit with a distance of 1,185,000 km (736,325 miles) from the moon. With one orbit like this, it will then move into a lunar orbit with an inclination of 30°, bringing it to within 40 km (25 miles) of the surface.

Over the course of a month, the two penetrators will be released individually, and they should burrow between 1-3 m (3-10 feet) into the surface. One will be released to land near the equator on the near side and the other will be released to land near the equator on the far side. Once the probes have been released, the orbiter will move to between a 200-300 km (125-186 miles) orbit to begin the mapping phase. Data from the penetrators will be transmitted to the orbiter every 15 days - when the orbiter passes over the penetrator.

The cost of the mission is estimated to be $135 million.

SELENE: SELenological and ENgineering ExplorerSELENE

This project is a joint venture of ISAS and NASDA (both Japanese agencies). SELENE will be designed to carry instruments to study the origin, evolution, and the tectonics of the moon from orbit. It will also be testing technologies for future lunar missions. It is actually a conglomeration of an orbiter, small relay satellite, and a small VLBI (Very Long Baseline Interferometry) satellite. The specific purpose of the VLBA is to conduct precise investigations on the position and precession of the moon.

Its launch in late 2005 was postponed until sometime in 2007 due to budget concerns. Once it is launched, it will take five days to travel to the moon where it will be put into a highly elliptical 120x13,000 km (75x8080 mile) near-polar orbit (95° inclination). The craft will then separate, and the relay satellite will be placed into a 100x2400 km (62x1500 mile) orbit and the VLBI into a 100x800 km (62x500 mile) orbit. The orbiter will then be placed in a 100 km (62 mile) circular orbit.

The planned duration of this project is approximately one year. If it lasts that long, a lower orbit of 40-70 km (25-43 miles) is being considered.


The Planet-C spacecraft is a Venus Orbiter designed to study the atmospheric dynamics of the planet, particularly the upper atmosphere super-rotation and 3-D motion of the lower atmosphere using various wavelengths of light. It will also measure atmospheric temperatures and look for evidence of volcanic activity and lightning. After launch in early 2008 on an M-V booster, an Earth swingby is planned on June 6, 2008, with arrival at Venus on September 4, 2009.

The satellite will have a dry mass of about 330 kg and carry 320 kg of propellant. Included in the science instruments will be a number of cameras equipped to return ultraviolet and infrared images. Planet-C has been approved as an official ISAS project.

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