— Mare Orientale, possibly the youngest impact basin on the Moon, has been probed in unprecedented detail by
‘s Chandrayaan-1 lunar orbiter.
Scientists from the Indian Space Research Organisation (ISRO) and their partners in Europe and the United States are due to present preliminary findings from this and other Chandrayaan-1 instrument investigations at the 40th Lunar and Planetary Science Conference at The Woodlands, Texas, beginning March 23, JitendraNathGoswami the mission’s chief scientist told Space News Feb. 6.
Chandrayaan-1, launched Oct. 22 and circling the Moon since Nov. 8, carries four Indian and six international payloads. Scientists operating the payloads met in
Jan. 29 to exchange information in preparation for the upcoming international lunar conference.
Mare Orientale, also known as the
, is located on the far western edge of the lunar nearside and is only partially visible from Earth.
NASA’s Apollo 17 crew photographed the bull’s-eye-shaped basin from orbit but the astronauts did not visit the site during their sample-collecting trip to the lunar surface. Believed to be the Moon’s youngest impact basin, the crater is blanketed by a relatively thin later of basalt, leaving much of the basin structure visible to Chandrayaan-1’s prying eyes.
ISRO scientists believe they have captured valuable data about the
‘s topological characteristics with the aid of Chandrayaan-1’s 5-meter resolution Terrain Mapping Camera and Hyperspectral Imager.
In a report to be presented at a March conference, ISRO scientists write that the initial results from the camera demonstrate the possibility of deriving relatively accurate “digital elevation models” from the imagery.
Another Chandrayaan-1 instrument that has acquired data on the Mare Orientale is the U.S.-supplied Moon Mineralogy Mapper developed by scientists at
, and NASA’s Jet Propulsion Laboratory,
scientists analyzing the mineralogy mapper’s data found that the peak ring of the basin “exposed a massive crustal layer of almost pure anorthosite,” an igneous rock that makes up about 60 percent of Earth’s crust. “A major new result is that the existence and distribution of massive amounts of anorthosite as a continuous stratigraphiccrustal layer is now irrefutable,” they said in a report to be presented at the lunar conference.
While three of Chandrayaan-1’s instruments have been working since the spacecraft was still in Earth orbit, some instruments were not powered-on until later in the mission. “We were really worried about the thermal situation but now we know what precautions to take when the anomaly appears again,” Goswami said in a Feb. 6 interview. “Presently all 10 instruments onboard have been commissioned and they are working excellently.”
For the Mini-Synthetic Aperture Radar, a miniaturized imaging radar designed to search for evidence of ice in permanently shadowed areas of the Moon, the first systematic mapping season began in mid-January.
Developed by the Johns Hopkins University Applied Physics Laboratory in
, Mini-SAR will have three additional data-taking periods during 2009, allowing
scientists to obtain complete maps of both polar regions of the Moon at 75 meters-per-pixel, according to a report to be presented at the lunar conference.
According to Goswami, one instrument that worked beyond expectations is the Chandrayaan-1 Imaging X-ray Spectrometer, known as C1XS and pronounced “kicks,” developed by Rutherford
. It is designed to measure the abundances of major rock-forming elements by detecting tell-tale X-rays they emit when battered by solar flares.
“We thought that CIXS would not produce signals as the sun is in the longest solar minimum and is very quiet,” Goswami said.
Scientists, however, were surprised that on Dec. 12 it observed X-ray lines indicting the presence of magnesium, aluminum and silicon even though the solar flare that caused the X-ray fluorescence was exceedingly weak. “Initial results suggest that its performance as a science instrument will be outstanding,” the
scientists said in their report. Goswami hopes that CIXS will get busier solar activity in the coming months.
“We have collected good data but it has to be converted into science, which is a slow process,” Goswami said. “We are hopeful some science will definitely come out of Chandrayaan-1 even before the coming lunar conference.”