Sunday, April 15, 2012

Scientists at PRL suggest evidence of continued volcanism long after Tycho's formation

From "Tycho's flash-frozen inferno" (Lunar Pioneer/Lunar Networks), November 2, 2011: As impact melt briefly ran down the exterior side of the southeast brim of Tycho it pooled, cooled, and came to a halt in the cold vacuum of space long before 'finding its level.' PRL director Dr. Goswami and team suggest these and other melt pools are superimposed at positions suggesting extrusive volcanism at Tycho continued well after the impact event, 109 million years ago. LROC NAC observation M150578086R, LRO Orbit 7324, January 25, 2011; resolution 71 centimeters per pixel, incidence angle 69.84° from 44.74 kilometers [NASA/GSFC/Arizona State University].
EDITOR'S NOTES: RE: "Claim supported by discovery of two-km high peak with boulders." Obviously the central peak of Tycho is not a recent discovery, though the nature of the large boulder situated near it's apex, discussed here last July, was a recently resolved feature, and before either Chandrayaan-1 or the on-going Lunar Reconnaissance Orbiter missions. That feature is plainly visible in Terrain Camera images returned by Japan's SELENE-1 (Kaguya) in 2009. Now without reading the full paper by Dr. Goswami, whose credibility is well established along with that of the PRL, we are left a bit confused by the report that follows which suggests 100 million year-old features related to a 100 million year-old impact should be thought of as unusual. Nevertheless, a hint that impact melt and other features superimposed upon Tycho might be evidence of volcanism continuing for an unusually long time after Tycho's formation is intriguing.
Addendum 1 - 201204141459 ut: Charles Wood discussed and linked to the abstract discussed below at his definitive website LUNAR PICTURE of the DAY (LPOD), April 14, 2012.
Addendum 2 - 201204152359 ut: Dr. J. N. Goswami, director of India's noted Physical Research Laboratory (PRL), who is quoted in the Deccan Herald news article below, was gracious enough to forward to our group a complete copy of the newsworthy research regarding the interesting possibility of an extended and dynamic period of volcanism near the central peak of Tycho. We will follow up on this shortly. - JR.

"Indian scientists find volcanic activity on moon"

Kalyan Ray
Deccan Herald

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.

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?

Analyzing data collected by Chandrayaan-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.

From "LROC Featured Image, 'Tycho Central Peak Spectacular,'" July 5, 2011: Oblique view of summit area of the central peak of Tycho. The boulder resting inside a summit notch is 120 meters wide, and the image area is about 1200 meters across. LROC Narrow Angle Camera (NAC) observation M162350671L & R, LRO orbit 9059, June 10, 2011. Zoom in on the fill-sized NAC mosaic HERE [NASA/GSFC/Arizona State University].
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.

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.

Additional illustration for Dr. Mark Robinson's "Tycho Central Peak Spectacular," From almost an entirely different angle and illumination, Japan's lunar orbiter Kaguya (SELENE-1) released a Terrain Camera image of Tycho's interior in 2009. Once again, the boulder, situated on a tiny melt plain near the very highest point of Tycho's central peak, is seen. Another large "melt plain" can also be seen at a lower elevation, above left center, a high valley between summits 600 meters above the jumbled, relatively fresh impact melt-based and chaotic Tycho interior floor [JAXA/SELENE].
“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,” Prof. 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. The findings were reported in the April 10 issue of ‘Current Science’.

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.

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