apr 172012


Breaking through a popular perception of moon being a geologically inert place for the last three billion years, Indian scientists have found new evidence of the recent volcanic activities inside a lunar crater, opening up a new window for research.


Recent findings from Chandrayaan-1, and NASA’s Lunar Reconnaissance Orbiter (LRO) show evidence of recent lunar volcanism. These findings were published in the April 2012 issue of Current Science, a journal by the Indian Academy of Sciences.


a: Chandrayaan-1 TM4-16-12_tychoC data mosaic of Tycho crater. b: Three-dimensional image of Tycho central peak with vertical exaggeration factor of 5.0 showing two distinct lava ponds. Flow direction and pattern is marked with a thick dotted line. A set of fractures is marked with thin dotted lines. Credit: Chauhan et al., 2012

The discovery of a 2-km high peak with large boulders comfortably sitting atop inside a crater and signatures of strong volcanic activities all around the peak may eventually aid scientists to solve one of the long-standing lunar mysteries – what is the moon made of?Analysing data collected by Chandrayan-I and USA’s Lunar Reconnaissance Orbiter, a team at the Physical Research Laboratory (PRL) in Ahmedabad, found evidences of volcanic vent, lava pond and lava channels as recent as 100 million years old inside the ‘impact crater’, thus implying that the moon was not a geologically quiet, rather, it was an active place.

The lunar volcano was different from the volcanoes seen on earth. Possibly, there was no explosive eruption. The magma may have oozed out silently through the vents. The discovery – if supported by further studies in future – has the potential to change the commonly held belief on geological history of moon, the team claimed. Instruments on board Chandrayaan-II, to be launched in 2013, will take a closer look at the peak.

Constantly bombarded by asteroids and meteors, moon has many scars on its face – the impact craters. The high-velocity collisions with lunar surface creates “impact-induced” mounds. The 2-km high peak in Tycho – a 110 million year old crater, is one such peak.

The fresh evidence of volcanic activity suggests magma may have been released from the interior as a consequence of the impact that led to the formation of the crater in the first place. This suggests that the moon was geologically active from inside when the carter was formed.

“Either the signatures were made post formation of the crater or sub-surface solidified magma which was released due to the impact. We can’t be sure at this point, therefore, require more studies from other craters.

“But unlike on earth, we cannot have a deep drilling project on moon to understand its deeper crust,” J N Goswami, PRL director and lead scientist of Chandrayaan told Deccan Herald.

“We found the inner crustal material exposed on the central peak of Tycho,” said Prakash Chauhan, a PRL scientist. The study, he claimed, changed views about geological history of the moon and brought out details of more recent modifications of the lunar surface.

“A surprise findings revealed the presence of large boulders–about 100 meter in size –on top of the peak. Nobody knew how did they reach the top,” Chauhan said.

Composition of lunar core and the nature of materials present on the surface remains one of the unsolved scientific problems. The evidence so far, has come mainly from the analysis of lunar rocks collected by Apollo missions, and analysis of images collected by a handful of spacecraft within the last six years including Chandrayaan-I.

a: High-resolution view of lava pond 1 using Chandrayaan-1 TMC data. b: Very high-resolution view of the lava pond 1 from LROC NAC image. Possible vent for the lava flow is marked with a solid circle. Lava flow directions are marked with a thick dotted line; and clasts deposited at the base of the flank are marked with a dotted circle. c: Close view of the lava pond showing fractures or fissures. Credit: Chauhan et al., 2012


“These findings have important implications towards the understanding of the mechanism of the formation and evolution of the moon’s central peaks and volcanic activity on the moon,” the report states.

The focus of this study was Tycho, a young impact crater of the Copernican Age in the southern highlands of the moon. This crater has a well-developed central peak with an altitude of two kilometers. The discovery of large boulders on top of a crater with signatures of strong volcanic activities around a peak sheds light on the moon’s history and composition.

“Our study provides direct evidence of volcanism on the central peak in the form of volcanic vents, boulders and lava ponds showing prominent cooling cracks and lava channels with well-defined flow fronts at several locations,” the authors state.

Read the full article: Chauhan P et al. (2012) Compositional and morphological analysis of high resolution remote sensing data over central peak of Tycho crater on the Moon: implications for understanding lunar interior.

Source: The Deccan Herald and NASA’s  Lunar Science Institute


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