7,925 research outputs found
Future scientific exploration of Taurus-Littrow
The Apollo 17 site was surveyed with great skill and the collected samples have been studied thoroughly (but not completely) in the 20 years since. Ironically, the success of the field and sample studies makes the site an excellent candidate for a return mission. Rather than solving all the problems, the Apollo 17 mission provided a set of sophisticated questions that can be answered only by returning to the site and exploring further. This paper addresses the major unsolved problems in lunar science and points out the units at the Apollo 17 site that are most suitable for addressing each problem. It then discusses how crucial data can be obtained by robotic rovers and human field work. I conclude that, in general, the most important information can be obtained only by human exploration. The paper ends with some guesses about what we could have learned at the Apollo 17 site from a fairly sophisticated rover capable of in situ analyses, instead of sending people
The lunar environment and its effect on optical astronomy
The Moon's geologic environment features: (1) gravity field one-sixth that of Earth; (2) sidereal rotation period of 27.3 days; (3) surface with greater curvature than Earth's surface (a chord along a 10 km baseline would have a bulge of 7.2 m); (4) seismically and tidally stable platform on which to make astronomical observations (most moonquakes have magnitudes of 1 to 2 on the Richter scale, within the earth's seismic noise, resulting in ground motions only 1 nm); (5) tenuous atmosphere (the total mass at night is only 10(exp 4) kg) that has an optical depth of 10(exp -6) and does not cause wind induced stresses and vibrations on structures; (6) large diurnal temperature variation (100 to 385 K in equatorial regions), which telescopes must be designed to withstand; (7) weak magnetic field, ranging from 3 to 330 x 10(exp -9) T, compared to 3 x 10(exp -5) T on Earth at the equator; (8) surface exposed to radiation, the most dangerous of which are high energy (1 to 100 Mev) particles resulting from solar flares; (9) high flux of micrometeorites which are not slowed down from their cosmic velocities because of the lack of air (data indicate that microcraters greater than 10 microns across will form at the rate of 3000/sq m/yr); (10) regolith 2 to 30 m thick which blankets the entire lunar surface (this layer is fine-grained (average grain sizes range from 40 to 268 microns), has a low density (800 to 1000 kg/cu m in the upper few mm, rising to 1500 to 1800 kg/cu m at depths of 10 to 20 cm), is porous (35 to 45 pct), cohesive (0.1 to 1.0 kN/sq m), and has a low thermal diffusivity (0.7 to 1.0 x 110-8 sq m/sec); about 29 pct of the regolith is less than 20 micron in size (this dust could pose a hazard to optical telescopes); (11) rubbly upper several hundred meters in which intact bedrock is uncommon, especially in the lunar highlands; and (12) craters with diameter-to-depth ratios of 5 if fresh and less than km across (larger and eroded craters have diameter-to-depth ratios greater than 5)
Geological considerations for lunar telescopes
The geological features of the Moon that may be advantageous for astronomical observations are listed and described. The Moon's geologic environment offers wondrous opportunities for astronomy and presents fascinating challenges for engineers designing telescope facilities on the lunar surface. The geologic nature of the stark lunar surface and the Moon's tenuous atmosphere are summarized. The Moon as a stable platform is described as is its atmosphere, surface temperatures, its magnetic field, its regolith, and its crater morphologies
Remote Assessment of Lunar Resource Potential
Assessing the resource potential of the lunar surface requires a well-planned program to determine the chemical and mineralogical composition of the Moon's surface at a range of scales. The exploration program must include remote sensing measurements (from both Earth's surface and lunar orbit), robotic in situ analysis of specific places, and eventually, human field work by trained geologists. Remote sensing data is discussed. Resource assessment requires some idea of what resources will be needed. Studies thus far have concentrated on oxygen and hydrogen production for propellant and life support, He-3 for export as fuel for nuclear fusion reactors, and use of bulk regolith for shielding and construction materials. The measurement requirements for assessing these resources are given and discussed briefly
Astronomy on the Moon: Geological considerations
The Moon is an excellent site for astronomical observations. This paper describes two geological aspects related to astronomy from the Moon. First it evaluates the sources of gases near a lunar base as input to calculations reported in a separate paper on the growth of an artificial lunar atmosphere. The results suggest that mining for He-3 could produce the most gas (1 kg/sec), but rocket exhaust (0.1 kg/sec) and habitat venting (0.5 kg/sec) are also important. Second, the paper discusses criteria that need to be considered when determining the site of a lunar astronomical facility. These are longitude and latitude (equatorial sites are favored), topography (important to be relatively flat for ease of installation), distance from a lunar base (to be free of seismic noise, dust, and gases), the site's value to lunar geoscience (other factors being equal, a geologically diverse site is better), and its value as a materials resource (mining and observatories are incompatible)
Unauthorized Immigrants and Their U.S.-Born Children
Analyzes data on the number, age distribution, fertility, and family structure of legal and unauthorized immigrants and the percentage of their children among all U.S. children and of the U.S.-born and foreign-born among their children
Stewardship Plan for Four Conservation Easements Held by the Town of Newfields
In 2005 the Town of Newfields, NH was awarded a grant by the New Hampshire Estuaries Project. The Eligible Activity applied for, under the category of Land Conservation and Natural Resource Protection was “Development of monitoring plans for town-held easements on conservation lands”. The Town identified four properties on which the they hold conservation easements as the focus of the project. Newfields’ goal in applying for the grant were to have each property visited by the contractor and a local volunteer, conduct an interview with the landowner and a conduct a ground monitoring of the property. Following the visits, baseline documentation reports and a stewardship plan for each easement property would be created. As a part of the plan, the Town also hoped to address policy considerations relating to stewardship of easements
Marrying Out: One-in-Seven New U.S. Marriages Is Interracial or Interethnic
Examines trends in and attitudes toward marriages between different races/ethnicities since 1980, including rates of intermarriage by race/ethnicity, gender, region, education, and age. Considers factors behind the trends, including immigration patterns
ARE U.S. FARM PROGRAMS GOOD PUBLIC POLICY? TAKING POLICY PERFORMANCE SERIOUSLY
Distributional analysis is employed to assess the ethical acceptability of agricultural policy along plurastic moral criteria. Using 1999 micro-data from USDA ARMS survey and the Federal Reserve's Survey of Consumer Finances, we discuss policy performance (measured as the effect of direct government payments on the distribution of incomes and profits) relative to policy goals. We show that current programs only minimally address the post-?farm problem? objective of providing a safety net, and the goal of providing an abundant supply of agricultural products is potentially well-implemented given institutional constraints.Agricultural and Food Policy,
Geoscience and a Lunar Base: A Comprehensive Plan for Lunar Exploration
This document represents the proceedings of the Workshop on Geoscience from a Lunar Base. It describes a comprehensive plan for the geologic exploration of the Moon. The document begins by explaining the scientific importance of studying the Moon and outlines the many unsolved problems in lunar science. Subsequent chapters detail different, complementary approaches to geologic studies: global surveys, including orbiting spacecraft such as Lunar Observer and installation of a global geophysical network; reconnaissance sample return mission, by either automated rovers or landers, or by piloted forays; detailed field studies, which involve astronauts and teleoperated robotic field geologists. The document then develops a flexible scenario for exploration and sketches the technological developments needed to carry out the exploration scenario
- …