§ 2.5 Lunar Probes - History and Future
Future Lunar Probes
"Europe's first lunar adventure", a probe called SMART-1, is the first probe in Europe's Small Missions for Advanced Research in Technology (SMART). Launched in September 2003, SMART-1 is using a slow but fuel efficient electric propulsion system to boost it to lunar orbit over approximately 15 months, and is scheduled to arrive in January 2005. It will orbit the Moon for nominally 6 months. Its primary mission is to flight test an electric propulsion system (Stationary Plasma Hall-Effect thruster, as discussed in the PERMANENT transportation section) and other new spacecraft subsystems including various sensors. The home page for SMART-1 is sci.esa.int/smart-1/ but skip over to the subpage sci.esa.int/content/doc/10/2320_.htm for a good description.
 Japan is developing a lunar probe called Lunar-A. It was scheduled for launch in 2004 but the American manufacturer of its thrusters recalled them, thereby delaying the launch to 2005. In addition to more imaging of the Moon, Lunar-A will also measure near-surface thermal properties and heat flux, moonquakes, and the lunar interior structure and core from those moonquakes. To achieve that, it will deploy two surface penetrators equipped with heat sensors and seismometers, which will impact the surface and embed themselves between 1 and 3 meters deep. Designed to withstand an impact of 10,000 G's, each of the two impactors has its own de-orbit and descent control thrusters. More details here
Japan is launching another mission in 2005, too, called SELENE (SELenological and ENgineering Explorer), currently scheduled for September. It consists of 3 satellites. Complimentary to Lunar-A, SELENE will obtain data on elemental abundance, mineralogical composition, topography, geology, gravity, and the lunar and solar-terrestrial plasma environments. More details here ("Selene" is the Greek goddess of the Moon. It is also the name of the second daughter of the PERMANENT curator.)
India will launch its first lunar mission, Chandrayaan-1, in 2007 or 2008. The project was announced by the Prime Minister on Independence Day in India in 2003, and by the time of this writing in April 2004, the program was well underway. For more information, see www.chandrayaan-1.com
History of Lunar Probes
The first NASA lunar probes were the NASA Ranger series between 1961 and 1965, which were all designed to impact the Moon and take high resolution images shortly before these impacts, e.g., 0.5 meters resolution. The first six failed but the last three were successful.
The next generation of spacecraft were soft landers, the Lunar Surveyor series. Surveyor 1 soft-landed in June, 1966. There were seven Surveyors, though two failed (one engine failed to ignite, another just lost communication shortly before landing). The last was in January 1968. The Surveyors took detailed photos of candidate Apollo landing sites, tested the surface with a scoop, and had an alpha scattering instrument for chemical analysis of the lunar soil.
In 1966 to 1967, NASA mapped 99% of the lunar surface with its five successful probes Lunar Orbiter 1 through Lunar Orbiter 5, achieving a resolution of 60 meters or better. Lunar Orbiter 5 mapped 36 preselected candidate Apollo sites to between 20 meter and 2 meter resolution.
Apollos 8 and 10 were the first manned missions to orbit the Moon in 1968 and 1969 and returned pictures. Apollos 11, 12, 14, 15, 16 and 17 were manned missions which landed on the Moon between 1969 and 1972, returning almost 400 kilograms (900 pounds) of lunar samples and data from various other experiments.
Russian probes were the first and the last to visit the Moon in the 1959-1976 era. Soviet Luna and Zond missions also photographed the Moon, with Luna 3 giving humanity the first view of the lunar farside in 1959. There were a total of 24 Luna missions, with the early missions being photographic orbiters and the latter being landers. The Luna 13 robotic probe successfully soft landed on the Moon in February, 1966, beating the American soft-lander probe by four months, and providing detailed pictures of the Moon's surface. Luna 16 in 1970 was the first of three Soviet probes to returned a lunar sample (after Apollo 11). Some of the Luna probes also had robotic rovers to drive around the lunar surface, called Lunokhod. The five Zond spacecraft were of a different design and operated concurrently between 1965 and 1970, all photographic orbiters, while the Luna missions started focusing on landing on the Moon. The Luna 24 mission was the last mission to the Moon in 1976, a sample return mission.
After 1976, the Moon was ignored by space probes until the U.S. Department of Defense's new Strategic Defense Initiative Organization (SDIO, aka "Star Wars") flew the Clementine 1 probe to map the Moon's surface with modern instruments, in conjunction with NASA. Clementine 1 arrived at the Moon in February 1994.
(Actually, the NASA probe Galileo, headed for Jupiter, turned on some of its equipment during two brief flybys of the Moon in 1990 and 1992 during gravity assist maneuvers as a result of its shoestring launch vehicle budget. However, the amount of data acquired was small and very general in nature.)
Clementine 1 entered a polar orbit around the Moon in order to map its entire surface. Clementine 1 orbited the Moon for more than two months, totalling over 300 orbits, from February 19 to May 5, 1994. Clementine 1 left lunar orbit to rendezvous with near Earth asteroid 1620 Geographos, but a computer malfunction caused the spacecraft to fail before it reached the asteroid.
In addition to the valuable data it collected on the Moon as a result of being the first probe to map the Moon using modern instruments, Clementine 1 was a fantastic sociopolitical success on its lunar leg because it discovered ice at the lunar south pole, the first indication of any concentration of water on the Moon.
As a result of Clementine 1's discovery of ice on the Moon, interest in the Moon dramatically increased and political pressure resulted in NASA funding its first probe to the Moon in more than 20 years, the Lunar Prospector. Unfortunately, funding for Clementine 2, a Department of Defense mission to several asteroids near Earth, was vetoed by President Clinton (line item veto) after it successfully passed funding by a more enlightened Congress. However, funding for the Lunar Prospector probe passed both Congress and the President.
Like Clementine 1, Lunar Prospector was built quickly and cheaply. Mission cost was just $63 million. The entire process of development to completion and testing was accomplished in less than 2 years. When full of fuel, the spacecraft weighs only 295 kg (650 lb). That's much less than your car -- an average size car weighs about four times that much. Lunar Prospector carried five instruments to study the moon, and the spacecraft was largely made from off-the-shelf, flight-proven hardware -- used whenever feasible. Lunar Prospector launched in January, 1998, almost exactly 4 years after the launch of Clementine.
Lunar Prospector's five sensors include a Gamma Ray Spectrometer (GRS) and a Neutron Spectrometer (NS) to provide global maps of elemental abundances on the lunar surface (in addition to water). The NS sensor can detect traces of water down to 10 parts per million (PPM), though it found vastly higher concentrations than that. The data also reports on the mapping of the global distribution of major rock types, key resources and trace elements in all other places on the Moon.
The data from Clementine 1 and Lunar Prospector make obsolete much of the data from previous lunar orbiters, but does not make obsolete the data from the Apollo samples and other imaging and geophysical data from other landers in the 1960s and 1970s.
Data from all the lunar probes, including the massive amounts of detailed data from Clementine 1 and Lunar Prospector, are open to the public and can be acquired by internet at the NASA National Space Science Data Center (NSSDC) at http://nssdc.gsfc.nasa.gov/planetary/planets/moonpage.html or ordered on CD-ROMs.
|
Probes History
Back to 
Forward to