Scientists and educators at Baylor College of Medicine are using space life sciences research areas as themes for middle school science and health instructional materials. This paper discusses study findings of the most recent unit, Food and Fitness, which teaches concepts related to energy and nutrition through guided inquiry. Results of a field test involving more than 750 students are reported. Use of the teaching materials resulted in significant knowledge gains by students as measured on a pre/post assessment administered by teachers. In addition, an analysis of the time spent by each teacher on each activity suggested that it is preferable to conduct all of the activities in the unit with students rather than allocating the same total amount of time on just a subset of the activities. 相似文献
We consider four aspects of interstellar chemistry for comparison with comets: molecular abundances in general, relative abundances
of isomers (specifically, HCN and HNC), ortho/para ratios for molecules, and isotopic fractionation, particularly for the
ratio hydrogen/deuterium. Since the environment in which the solar system formed is not well constrained, we consider both
isolated dark clouds where low mass stars may form and the "hot cores" that are the sites of high mass star formation. Attention
is concentrated on the gas phase, since the grains are considered elsewhere in this volume.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) comprises the hardware and accompanying science investigation on the New Horizons spacecraft to measure pick-up ions from Pluto’s outgassing atmosphere. To the extent that Pluto retains its characteristics similar to those of a “heavy comet” as detected in stellar occultations since the early 1980s, these measurements will characterize the neutral atmosphere of Pluto while providing a consistency check on the atmospheric escape rate at the encounter epoch with that deduced from the atmospheric structure at lower altitudes by the ALICE, REX, and SWAP experiments on New Horizons. In addition, PEPSSI will characterize any extended ionosphere and solar wind interaction while also characterizing the energetic particle environment of Pluto, Charon, and their associated system. First proposed for development for the Pluto Express mission in September 1993, what became the PEPSSI instrument went through a number of development stages to meet the requirements of such an instrument for a mission to Pluto while minimizing the required spacecraft resources. The PEPSSI instrument provides for measurements of ions (with compositional information) and electrons from 10 s of keV to ~1 MeV in a 160°×12° fan-shaped beam in six sectors for 1.5 kg and ~2.5 W. 相似文献
This introductory address provides a brief overview and a timeline for construction of the International Space Station, beginning with the July 2000 launch of the Russian Service Module, Zvezda, and ending with the Mission STS-112. 相似文献
Solid Rocket Boosters (SRB's) became viable contenders as the booster for the Space Transportation System (STS) early in the concept studies of Space Shuttle because of their low development cost compared with equivalent liquid propellant boosters. Program risks and costs have been held down by scaling and adapting existing technology to the 146 in. SRB selected for development. To retain this low cost edge for the operational phase, NASA has concentrated on maintaining or reducing the cost of expendables and has demonstrated the feasibility of reusing the expensive nonexpendable SRB hardware. Drop tests of Titan III motor cases and nozzles in 1973 proved that boosters could survive water impact at vertical velocities of approx. 100 ft/s. SRB components have been designed with reuse in mind. In most cases, hardware designed for ascent will withstand water impact loads with little modification.
Cost effective refurbishment is a foremost design consideration. Continuing review of each component assures that design for reusability and/or cost of refurbishment does not become so costly that a low-cost expendable approach may be more cost effective.
The cost of expendables has been minimized by selecting proven propellants, insulations, and nozzle ablatives whose costs are well known. The propellant, which is approx. 95% of the expendables, is the lowest cost composite formulation available. As lower cost ablative materials such as pitch carbon fibers become available in quantity and are reliably demonstrated, they will be introduced to reduce operations costs.
Thus, by use of proven technology, low cost expendables and reuse of more expensive non-expendables, the development and operations costs of SRB's are held to a level that make the SRB an economical booster for the Space Shuttle. 相似文献
The Search for ExtraTerrestrial Intelligence (SETI) finally has its own full-time telescope. The Allen telescope array (ATA) in Northern California was dedicated on October 11, 2007. This array, which will eventually be composed of 350 small radio antennas, each 6.1 m in diameter, is being built as a partnership between the SETI Institute and the University of California Radio Astronomy Laboratory. Last October, Paul G. Allen (who provided the funds for the technology development and the first phase of array construction) pushed a silver button and all 42 antennas of the current ATA-42 slewed to point in the direction of the distant galaxy M81. Specialized electronic backend detectors attached to the ATA began making a radio map of that galaxy and simultaneously began SETI observations of HIP48573, a G5V star near M81 on the sky and a distance of 264 light years from Earth. The Allen telescope array will greatly improve the speed of conducting SETI searches over the next few decades, and it will allow a suite of different search strategies to be undertaken. This paper summarizes some of the earliest SETI observations from the array, and describes the search strategies currently being planned. 相似文献