A smashing end for Japanese lunar orbiter mission
BY STEPHEN CLARK
Posted: June 10, 2009
An Australian telescope observed the controlled crash of Japan's Kaguya lunar probe into the moon Wednesday, an important warm-up act before a NASA impactor attempts a similar feat in October with much higher stakes.
Kaguya smacked into the moon at about 1825 GMT Wednesday, or about 3:25 a.m. Japan time Thursday.
The spacecraft hit the moon at 80.4 degrees east longitude and 65.5 degrees south latitude, or near the lower right quadrant of the moon's near side as viewed from Earth, according to the Japan Aerospace Exploration Agency.
The Anglo-Australian Telescope's infrared wide-field camera and spectrograph, called IRIS2, detected the flash of the high-speed impact.
"A bright impact flash was seen close to the predicted time," said Jeremy Bailey, one of the observers.
Bernard Foing, project manager of the European Space Agency's SMART 1 mission, alerted Australian scientists of Kaguya's impact.
"Congratulations for the successful observation of (the) Kaguya impact at the Anglo-Australian Telescope," Foing wrote in an email to Bailey and other scientists.
Foing is executive director of the International Lunar Exploration Working Group, an organization established by the world's space agencies as a public forum for scientists.
SMART 1 crashed into the moon in 2006 after a technology demonstration mission in lunar orbit. The Canada-France-Hawaii Telescope at Mauna Kea observed that event.
Kaguya was five times heavier than SMART 1 and was aiming for a region in darkness near the terminator. Those conditions meant dust from the impact could be thrown into space and illuminated by sunlight.
Scientists will analyze the imagery to look for evidence of a dust plume like the one produced by SMART 1, officials said.
The spacecraft, about the size of a sports utility vehicle, was remotely commanded to lower its orbit and hit the moon as its fuel supply dwindled.
Officials said they wanted to end the mission before Kaguya ran out of fuel because that would eventually lead to an uncontrolled impact.
"At low altitude, a lot of fuel is needed to maintain the orbit," Foing said. "We take advantage of the opportunity to create a well-characterized impact experiment."
Kaguya, also named SELENE, launched in September 2007 and arrived at the moon about 20 days later to begin nearly two years of observations using 15 science payloads.
The instruments included a stereo camera suite, an array of sensors designed to sniff for hydrogen, a laser altimeter that measured the shape of the moon, and a payload to probe the local radiation environment.
Kaguya also carried a high definition camera that beamed back stunning video imagery of the moon.
The spacecraft released two daughter satellites after entering lunar orbit. The 110-pound satellites helped Kaguya study the moon's gravity field and the lunar ionosphere. One of the probes was guided into the moon in February, and the other is still being operated.
Wednesday's impact was similar to the demise of other lunar missions, including SMART 1.
NASA's Lunar Prospector was ordered to plunge into a permanently shadowed crater near the moon's south pole in 1999.
The Chinese Chang'e 1 orbiter ended its exploration of the moon in March with a lunar impact.
Scientists must draw upon telescopes around the world to observe spacecraft impacts.
Lunar Prospector's final moments were studied by the orbiting Hubble Space Telescope, the McDonald Observatory in Texas and the Keck Observatory in Hawaii.
NASA is launching the first devoted lunar impactor next week to begin a four-month cruise through space that will culiminate with an October crash into a permanently shadowed crater at the moon's south pole.
The mission is called the Lunar Crater Observation and Sensing Satellite, or LCROSS.
The spacecraft carries a complex group of sensors that will give scientists their closest look of an impact as the probe's Centaur rocket smashes in the moon. Spectrometers aboard LCROSS will attempt to sense hydrogen and water molecules in the material ejected from the crater.
The LCROSS impact sequence will also be observed by Hubble and an array of Earth-based telescopes.
LCROSS will launch with the Lunar Reconnaissance Orbiter, the first mission in NASA's plans to return humans to the moon.