ASU-IPF-2888

	ASU-IPF-2888 PR Set: 2008-09 #2888 Image Title: Central Peak and Southern Wall of Tycho Crater Original Source #:2008.08.15 Mission: SELENE (KAGUYA) Instrument: TC ASU-IPF-2888.jpg (105 KB) quick view ASU-IPF-2888.tif (6.81 MB)

Tycho Crater, located on the lunar nearside in the highlands of the southern hemisphere at 43S, 7W, is a young crater formed by an impact about 100 million years ago. On nights when the Moon is fully lighted, you can see bright rays coming out from Tycho Crater.

This image is part of a two minute 3D Flythrough movie that was made with gradually changing the aspect of Stereo TC camera image data and DTM extracted from the image data. The movie starts with an overview image of Tycho Crater, then approaches the central peak, flies along the steep slope of the inner wall, flies over the backside of the crater, and approaches the central peak again.

The study of Tycho Crater contributed to the development of lunar science. The first data on the chemical composition of the lunar highlands were obtained by the analytical instrument onboard Surveyor 7*, which soft-landed about 20 km north of the rim of Tycho in 1968. Dr. J. A. Wood of the Smithsonian Astrophysical Laboratory discovered some tiny fragment of anorthosite in the regolith (soil) samples collected by the Apollo 11 astronauts. Because of the observation that the chemical composition of the fragments was similar to that of Tycho taken by the Surveyor, Dr. Wood inferred that these fragment were ejected from Tycho by the impact. He proposed the lunar magma ocean hypothesis* in order to account for his finding that the lunar highlands are composed of anorthosite. One of the major objectives of the subsequent Apollo missions was to find a pristine anorthosite rock in the highlands.

The impact that created Tycho Crater ejected highland anorthositic crust all over the near side of the Moon. This impact by a small asteroidal body took place about 100 million years ago, when the dinosaurs inhabited the Earth. It was, however, still a relatively recent event in lunar history, and the effects of the impact event can clearly be seen in the movie.

*1) In preparation for the manned lunar missions of the Apollo Program, NASA developed soft-landing techniques with the Surveyor Program. Surveyor 7 was the final spacecraft of the series and landed near the north rim of Tycho Crater on 10 January 1968 (UT). During this mission, many photographs of the lunar highland landscape were taken and a geological survey was performed.

*2) “Lunar magma ocean hypothesis”: To explain the formation of anorthosite that the lunar surface was once completely molten to a depth of about 200 km, thus forming a “lunar magma ocean.” This hypothesis has contributed not only to lunar science but also to ideas about the formation of the Earth.