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Tycho crater '' NASA  photo''
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433
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S
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112
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W
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85 km
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48 km
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12
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is a prominent
Lunar Impact Crater located in the southern lunar highlands. To the south is
Street Crater ; to the east
Pictet , and to the north-northeast is
Sasserides Crater . The surface around Tycho is replete with craters of various differing radii, many overlapping still older craters. Some of the smaller craters are secondary craters formed from larger chunks of ''ejecta'' from Tycho.
Tycho is a relatively young crater, with an estimated age of 108 million years, as estimated from samples of the crater rays recovered during the
Apollo 17 mission. The crater is sharply defined and free of the wear that affects older craters. The interior has a high
Albedo that is prominent when the sun is overhead, and the crater is surrounded by a distinctive
Ray System forming long spokes that reach as long as 1,500
Kilometer s. Sections of these rays can be observed even when Tycho is only illuminated by earthlight.
centered on Tycho]]
The
Ramparts beyond the rim have a lower albedo than the interior for a distance of over a hundred kilometers, and are free of the ray markings that lie beyond. This darker rim may have been formed from minerals excavated during the impact.
Its inner wall is slumped and d, sloping down to a rough but nearly flat floor exhibiting small, knobby domes. The floor displays signs of past volcanism, most likely from rock melt caused by the impact. Detailed
Photograph s of the floor show that it is covered in a cross-crossing array of cracks and small hills. The central peaks rise 1.6 kilometers above the floor, and a lesser peak stands just to the northeast of the primary
Massif .
Infrared observations of the lunar surface during an eclipse have demonstrated that Tycho cools at a slower rate than other parts of the surface, making the crater a "hot spot". This effect is caused by the difference in materials that cover the crater.
The rim of this crater was chosen as the target of the
Surveyor 7 mission. The robotic spacecraft safely touched down north of the crater in January,
1968 . The craft performed chemical measurements of the surface, finding a composition different from the ''maria''. From this one of the main components of the highlands was theorized to be
Anorthosite , an
Aluminium -rich mineral. The crater was also imaged in great detail by the
Orbiter V .
From the 1950s through the 1990s, NASA aerodynamicist Dean Chapman and others advanced the "lunar origin" theory of
Tektites . Chapman used complex orbital computer models and extensive wind tunnel tests to support the theory that the so-called Australasian tektites originated from the Rosse ejecta ray of Tycho. Until the Rosse ray is sampled, a lunar origin for these tektites cannot be ruled out.
This crater was drawn on lunar maps as early as
1645 , when
Antonius Maria Schyrleus De Rheita depicted the bright ray system.
The Tycho crater figures prominiently in the film and book '''', in which it is the location of a mysterious alien monolith which "appears to have been deliberately buried."
It also serves as the location of "Tycho City" in ''''; a lunar metropolis by the 24th century. (Even though it didn't exist in
2063 ; the point in history where the crew of the ''
Enterprise '' had travelled to,
Commander Riker claimed he could see it from the surface of the Earth.)
By convention these features are identified on Lunar maps by placing the letter on the side of the crater mid-point that is closest to Tycho crater.
