Crater Tycho Research Articles

Radar Mapping of the Moon at 162 Mhz

The result of Lunar radar mapping observations are presented, which were made at Jodrell Bank in January and February 1970 at 162.4 MHz in the depolarized return. The Maps show that most of the depolarized return comes from the highland regions. No significant return has been detected from the Maria. Certain isolated features are particularly prominent, notably the craters Tycho and Theophilus which appear almost equally intense, also the areas around Werner and Fourier. Various other features can be identified with less reliability. These results are discussed in qualitative terms.

Lunar rocks and thermal anomalies

Recent microwave and infrared spectral observations of several of the large bright-rayed craters on the moon suggest that the thermal anomalies in these craters are produced by large rocks, boulders, and exposed rock strata. The data for the crater Tycho can be simulated by a surface consisting of 16% loose rocks of 1-meter size and 4% exposed rock strata.

Fluorine and other trace elements in lunar plagioclase concentrates

The F contents of plagioclase concentrates from Apollo 11 fines and an anorthosite inclusion from an Apollo 12 breccia are of the order of 100 ppm. This is very much lower than the ∼ 2500 ppm F found by Surveyor VII in soil of anorthositic composition at the crater Tycho. Thus it appears that there is a negligible admixture of this type of terra material at the Tranquillitatis and Procellarum landing sites. Apollo 14 soils from Fra Mauro are rich in plagioclase but contain no more F than the mare soils. In addition to F the contents of Br, Ba, U, Ru and Os were measured in the Apollo 11 and 12 plagioclase concentrates and in rock 12040 and core sample 10004.

Map of lunar radar reflectivity at 7.5-m wavelength

The radar reflectivity of a substantial portion of the earth-visible lunar surface has been mapped at a wavelength of 7.5 m. This mapping—the first to use interferometric techniques in lunar observations—demonstrated that delay-Doppler mapping of the moon is possible at wavelengths of several meters. In the map that was obtained, the maria at a given angle of incidence had echo powers approximately half that of highlands at the same angle of incidence. Also, an enhancement associated with the lunar crater Tycho was observed.

Chemical Composition of the Lunar Surface in a Terra Region near the Crater Tycho

More precise and comprehensive analytical results for lunar surface material in a terra region have been derived from the data of the alpha-scattering experiment on Surveyor 7. The silicon content and the low sodium abundance are close to that of mare material. The abundances of titanium and iron are at least a factor of 2 lower, whereas the abundances of aluminum and calcium are significantly higher. The analytical results provide direct evidence for chemical differentiation in the moon and indicate a lunar crust of appreciably lower density than the whole moon and with lower density and higher albedo than lunar mare material.

Chemical Analysis of the Lunar Surface in the Surveyor Program—Summary*

Chemical analyses of lunar surface materials were obtained in situ by Surveyors 5, 6, and 7. Mare samples were analyzed by Surveyors 5 and 6, which landed in Mare Tranquillitatis and Sinus Medii, respectively [Turkevich et al., 1967b, 1968]. The Surveyor‐7 analyses were made in a terra region near the crater Tycho, which is thought to be covered with éjecta from that crater [Patterson et al., 1969]. The two adjacent samples in Mare Tranquillitatis were at least partially covered with material thrown out by the footpads of the spacecraft as it slid down the side of a small crater.

Samples Returned by Apollos 11 and 12 and Their Interpretation: ABSTRACT

Lunar samples returned by Apollo 11 and 12 from Tranquility Base and the Ocean of Storms can be classified into 3 major types: (1) mafic holocrystalline rocks, (2) breccias and microbreccias, and (3) particulate material. The mafic holocrystalline rocks mostly have familiar volcanic and/or shallow intrusive rock textures. These rocks mostly appear to be a closely related suite, but have a wide range of modal mineralogy. The major minerals are calcic plagioclase, clinopyroxene, olivine, and ilmenite. Breccias and microbreccias are predominantly lithified particulate material from the lunar regolith, but other types of breccias may also be present. The microbreccias and particulate material contain lithic fragments that have a much wider range of modal mineralogy than the l rge rocks. Among the lithic fragments are a small percentage of anorthosite and other plagioclase-rich rock fragments that are not represented by the larger specimens. These fragments may have originated from the lunar highlands, and their chemistry is similar to the Surveyor 7 analysis obtained in the lunar highlands near the crater Tycho. Petrographic evidence of shock metamorphism by meteoroid impact is abundant in the particulate material and common in the large rocks. Hypervelocity impact craters are present on the surfaces of most rocks and many small particles. These are commonly excellently preserved with a central approximately hemispherical glass-lined crater surrounded by a zone of spalling and abundant microfractures. Most glass particles in the lunar regolith appear to be mpact produced from the underlying rock fragments or fine material. The ages of the lunar mare materials dated thus far are very old, and many analyses show cluster around values of 3.6 and 4.2 b.y. The major and minor element and isotopic chemistry of lunar samples have some striking differences from terrestrial rocks and chrondritic meteorites. No lunar samples have been recognized that are similar to tektites in their chemistry or petrography. Planned Apollo 14 through 19 landing sites will offer the opportunity to sample different types of lunar features and should lead to conclusions about the genetic relations of the lunar mare and highlands, and the chemical heterogeneity of the Moon. End_of_Article - Last_Page 1786------------

Surveyor 7 Lunar Mission

The spacecraft Surveyor 7 landed on the outer rim of the crater Tycho on January 10, 1968. The landing area was selected to provide contrast with the mare sites of previous Surveyor landings. The surface at this highland site, associated with a major crater, was expected to consist of material that came from depth in relatively recent times. Surveyor 7 carried an alpha-particle backscattering instrument, a soil mechanics surface sampler, a television camera, and auxiliary mirrors and magnets. Data were obtained on the following properties of the lunar surface: topography and geology of the site; character, variety, density, size, distribution, and erosion of rocks; photometry and optical polarization associated with rock surfaces; nature and depth of the surface layer of fine particles; density, bearing capacity, bearing load-penetration relations, cohesion, adhesion, photometry and optical polarization of the fine particulate material; elemental composition and magnetic behavior of fine material and rocks; infrared brightness temperature; thermal inertia; microwave reflectivity. Microwave Doppler measurements were made of the motion of the landing site relative to earth. Pictures were taken of earth through polarizing filters, of lasers on earth, and of the solar corona.

Lunar Thermal Anomalies: Infrared Observations

The lunar craters Tycho, Copernicus, and Aristarchus have been observed during lunar night at wavelengths between 3 and 14 microns. After an initial fast decrease to a color temperature of 220 degrees K, the temperature remains nearly constant through the lunar night. The data suggest that these thermal anomalies (craters) contain hot and cold regions with the hot portions constituting 2 to 10 percent of the area and probably thermally connected to a subsurface temperatuer of about 200 degrees K.

A discussion on infared astronomy - Temperature distribution of the Moon

New techniques and instrumentation have been developed for the measurement of lunar surface temperatures. The infrared pyrometer has a resolution of about 10 seconds of arc. Special computing methods permit precise determination of the spots being measured on the lunar surface. A theoretical study has enabled the lunar surface temperature and its variation to be predicted during a lunation and during total eclipses of the Moon for a number of models. These include surfaces of solid rock, porous rock, dust, rubble, and various surfaces overlaid with different depths of dust. Certain areas, like the crater Tycho, appear to have no appreciable insulating layer of dust, although the environs may have some dust cover of indefinite thickness. Looking further to the future, we have calculated the temperature of the lunar surface during and immediately after the landing of the manned vehicle known as the Lunar Excursion Module, or lem. High temperatures will result from the exhaust flame of the retro-rocket, of some 1500 to 1600 °K immediately below the LEM. However, the cooling will be rapid and the astronauts could safely leave the craft 5 or 10 min after set-down.

Chemical Analysis of the Moon at the Surveyor VII Landing Site: Preliminary Results

The alpha-scattering experiment aboard Surveyor VII has provided a chemical analysis of the moon in the area of the crater Tycho. The preliminary results indicate a chemical composition similar to that already found at two mare sites, but with a lower concentration of elements of the iron group (titanium through copper).

Multiphase Development of the Lunar Crater Tycho

Data collected by Orbiter V when it landed on the Moon in 1967 provide information about the history of the crater Tycho. Volcanic eruptions seem to have been involved in the crater's development.

A radar study of the lunar crater Tycho at 3.8-cm and 70-cm wavelengths

Maps of the intensity distribution of radar echoes at 3.8- and 70-cm wavelengths from the lunar surface are presented for the region surrounding the crater Tycho. Surface resolution at 3.8 cm was between 1 and 2 km and at 70 cm between 7 and 10 km. The average scattering enhancement for Tycho at 3.8 cm was found to be 2.0 ± 0.3 when observed in the polarized mode (signals received using a sense of circular polarization orthogonal to that transmitted). At 70 cm, average enhancements of 5.0 ± 1.0 and 15 ± 2 in the polarized and depolarized modes, respectively, were observed. Using assumptions derived from earlier observations, that 15% and 6% of the average lunar surface at wavelengths of 3.8 and 70 cm, respectively, acts as a diffuse scatterer, we find from our observations that approximately 80% of the interior surface of tycho scatters diffusely at these wavelengths. Modulation of the intensity distribution associated with localized crater slopes is also observed.

Infrared Images of Tycho on Dark Moon

Infrared images of the thermal anomaly associated with the lunar crater Tycho were obtained during the lunar night after Tycho had ceased to be illuminated by the Suin for as long as 97 hours. In agreement with results of previous studies, these measurements show that the crater is warmer than its surroundings during the lunar night, and that the temperature of the thermal anomaly gradually decreases with time, being no longer detectable after new moon. This work provides strong evidence that the steeper crater walls facing the Sun before local sunset are warmer throughout the cooling phase, and that the Tycho anomaly is thus produced by solar, rather than internal, heat.

Enhancement of radar reflectivity associated with the lunar crater Tycho

The method of range-frequencypower density analysis has been applied to a study of the detailed radar reflectivity of the lunar surface. In the course of this study, an unusually high reflectivity has been found to be associated with the crater Tycho. The most likely explanation for this behavior appears to lie in a crater surface which is substantially rougher and perhaps somewhat denser than the typical lunar surface. Such an atypical surface might be expected for a crater as young as Tycho.

Eclipse Temperatures of the Lunar Crater Tycho

Shorthill, Borough, and Conley discovered during the total eclipse of the Moon on 13 March 1960 that the floor of the crater Tycho did not cool as much as the surrounding area, but remained some 40 to 60° warmer [1]. They found that other rayed craters, specifically Copernicus and Aristarchus, also remained warmer than their surroundings.

Infrared Isothermal Mapping of Certain Crater Areas of the Moon.

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Infrared Isothermal Mapping of Certain Crater Areas of the Moon. Saari, J. M. ; Shorthill, R. W. Abstract Detailed isothermal contour maps of relatively small areas of the moon which can be related to the visible surface features should prove valuable in deducing localized properties of the surface. To this end, measurements were made on a variety of crater areas with the 60-inch telescope at the Mount Wilson Observatory. The thermistor detector subtended a field of 8" (~ 10 miles on the moon's surface) when mounted at the Newtonian focus. A scan program was used which consisted of setting the clock near lunar rate and moving the telescope alternately east and west while the moon drifted in declination. The position of the detector on the moon was followed at the finder telescope and a description of its motion was recorded vocally on one channel of a tape recorder while the temperature signal was recorded simultaneously on the other channel. During totality of the September 5, 1960 eclipse scans were made over the rayed craters Tycho, Copernicus, Aristarchus and Proclus; all except the latter proved to be about 400C warmer than their surroundings. In addition, several drives across Kepler at the same time showed similar results. All of these areas were scanned during the full moon together with six other areas (Alphonsus, Cleomedes, Dionysius, Menelaus, Posidonius and Theophilus). In general, the infrared energy variations observed in these areas were comparable to those found over the rayed craters during totality, although the temperature differences are less because of the higher temperature. Explanations for the variations will be discussed in terms of geometry and localized variations in surface properties. This work was supported by the Air Force. Publication: The Astronomical Journal Pub Date: 1961 DOI: 10.1086/108496 Bibcode: 1961AJ.....66Q..52S full text sources ADS |