SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Statement of nasa administrator before house committee on science & astronautics - nasa programs, space science, astronautics
High-LET radiation is more efficient in producing complex-type chromosome exchanges than sparsely ionizing radiation, and this can potentially be used as a biomarker of radiation quality. To investigate if complex chromosome exchanges are induced by the high-LET component of space radiation exposure, damage was assessed in astronauts' blood lymphocytes before and after long duration missions of 3-4 months. The frequency of simple translocations increased significantly for most of the crewmembers studied. However, there were few complex exchanges detected and only one crewmember had a significant increase after flight. It has been suggested that the yield of complex chromosome damage could be underestimated when analyzing metaphase cells collected at one time point after irradiation, and analysis of chemically-induced PCC may be more accurate since problems with complicated cell-cycle delays are avoided. However, in this case the yields of chromosome damage were similar for metaphase and PCC analysis of astronauts' lymphocytes. It appears that the use of complex-type exchanges as biomarker of radiation quality in vivo after low-dose chronic exposure in mixed radiation fields is hampered by statistical uncertainties.
Food systems and meal components are constantly under review and development at the National Aerospace and Space Administration. The goal of this work is to generate a diet that meets the nutrient requirements of astronauts and satiates them. The constraints involved in shorter- and longer-term missions are described. The insight provided by observations of astronauts from the Skylab and Shuttle eras will allow researchers to consider the fact that, for any nutritional regimen to work, it must consider the limitations and taste buds of the individuals involved. Otherwise, the best diet design generated by their work may never be consumed.
Computer graphics is being employed at the NASA Johnson Space Center as a tool to perform rapid, efficient and economical analyses for man-machine integration, flight operations development and systems engineering. The Operator Station Design System (OSDS), a computer-based facility featuring a highly flexible and versatile interactive software package, PLAID, is described. This unique evaluation tool, with its expanding data base of Space Shuttle elements, various payloads, experiments, crew equipment and man models, supports a multitude of technical evaluations, including spacecraft and workstation layout, definition of astronaut visual access, flight techniques development, cargo integration and crew training. As OSDS is being applied to the Space Shuttle, Orbiter payloads (including the European Space Agency's Spacelab) and future space vehicles and stations, astronaut and systems safety are being enhanced. Typical OSDS examples are presented. By performing physical and operational evaluations during early conceptual phases. supporting systems verification for flight readiness, and applying its capabilities to real-time mission support, the OSDS provides the wherewithal to satisfy a growing need of the current and future space programs for efficient, economical analyses.
Melatonin and cortisol were measured in saliva and urine samples to assess the effectiveness of a 7-day protocol combining bright-light exposure with sleep shifting in eliciting a 12-hr phase-shift delay in eight U.S. Space Shuttle astronauts before launch. Baseline acrophases for 15 control subjects with normal sleep-wake cycles were as follows: cortisol (saliva) at 0700 (0730 in urine); melatonin (saliva) at 0130 (6-hydroxymelatonin sulfate at 0230 in urine). Acrophases of the astronaut group fell within 2.5 hr of these values before the treatment protocols were begun. During the bright-light and sleep-shifting treatments, both absolute melatonin production and melatonin rhythmicity were diminished during the first 3 treatment days; total daily cortisol levels remained constant throughout the treatment. By the fourth to sixth day of the 7-day protocol, seven of the eight crew members showed phase delays in all four measures that fell within 2 hr of the expected 11- to 12-hr shift. Although cortisol and melatonin rhythms each corresponded with the phase shift, the rhythms in these two hormones did not correspond with each other during the transition.
This report is a chronological compilation of narrative summaries of news reports and government documents highlighting significant events and developments in United States and foreign aeronautics and astronautics. It covers the years 1996 through 2000. These summaries provide a day-by-day recounting of major activities, such as administrative developments, awards, launches, scientific discoveries, corporate and government research results, and other events in countries with aeronautics and astronautics programs. Researchers used the archives and files housed in the NASA History Division, as well as reports and databases on the NASA Web site.
This report is a chronological compilation of narrative summaries of news reports and government documents highlighting significant events and developments in U.S. and foreign aeronautics and astronautics. It covers the years 2001 through 2005. These summaries provide a day-by-day recounting of major activities, such as administrative developments, awards, launches, scientific discoveries, corporate and government research results, and other events in countries with aeronautics and astronautics programs. Researchers used the archives and files housed in the NASA History Division, as well as reports and databases on the NASA Web site.
Currently, astronauts face significant health risks in future long-duration exploration missions such as colonizing the Moon and traveling to Mars. Numerous risks include greatly increased radiation exposures beyond the low earth orbit (LEO) of the ISS, and visual and ocular impairments in response to microgravity environments. The cardiovascular system is a key mediator in human physiological responses to radiation and microgravity. Moreover, blood vessels are necessarily involved in the progression and treatment of vascular-dependent terrestrial diseases such as cancer, coronary vessel disease, wound-healing, reproductive disorders, and diabetes. NASA developed an innovative, globally requested beta-level software, VESsel GENeration Analysis (VESGEN) to map and quantify vascular remodeling for application to astronaut and terrestrial health challenges. VESGEN mappings of branching vascular trees and networks are based on a weighted multi-parametric analysis derived from vascular physiological branching rules. Complex vascular branching patterns are determined by biological signaling mechanisms together with the fluid mechanics of multi-phase laminar blood flow.
Given the expressed NASA opinion that there is no perceived increase in astronaut fracture prevalence to warrant using Bis prophylactically, we surveyed the entire astronaut corps for evidence associating fracture incidence with spaceflight duration. Aim was to acquire fracture data to support the use of Bis to prevent spaceflight-induced changes in bone as a mitigation strategy for fracture risk.
One of the most vital life support systems is that used to provide the astronaut with an adequate thermal environment. State-of-the-art techniques are reviewed for collecting and rejecting excess heat loads from the suited astronaut. Emphasis is placed on problem areas which exist and which may be suitable topics for university research. Areas covered include thermal control requirements and restrictions, methods of heat absorption and rejection or storage, and comparison between existing methods and possible future techniques.
The principal gamma-ray-omitting radioisotopes produced in the body of astronauts by cosmic-ray bombardment which have half-lives long enough to be useful for radiation dose evaluation are Be-7, Na-22, and Na-24. The sodium isotopes were measured in the preflight and postflight urine and feces, and those feces specimens collected during the manned Apollo missions, by analysis of the urine salts and the raw feces in large crystal multidimensional gamma-ray spectrometers. The Be-7 was chemically separated, and its concentration measured in an all Na(T1), anticoincidence shielded, scintillation well crystal. The overall sensitivity of the experiment was reduced by almost all variables such as low concentrations of excreted cosmogenic radionuclides, high concentrations of injected radionuclides, low sample sizes, long delay periods before analysis, and uncertain excretion rates. The astronaut radiation dose in millirads, as determined by this technique, for the Apollo 7, 8, 9, 10, 11, 12, and 13 missions was 330, 160, 315, 870 ? 550, 31, 110, and 250 respectively. In view of these limitations this technique would be best applied to cases of unusually high exposures, such as that encountered from solar flares.
The principal gamma-ray emitting radioisotopes, produced in the body of astronauts by cosmic-ray bombardment, which have half-lives long enough to be useful for radiation dose evaluation, are Be-7, Na-22, and Na-24. The sodium isotopes were measured in the preflight and postflight urine and feces, and those feces specimens collected during the manned Apollo missions, by analysis of the urine salts and the raw feces in large crystal multidimensional gamma-ray spectrometers. The Be-7 was chemically separated, and its concentration measured in an all NaI (TL), anticoincidence shielded, scintillation well crystal. The astronaut radiation dose in millirads, as determined for the Apollo 7, 8, 9, 10, 11, 12, and 13 missions, was 330, 160, smaller than 315, 870 plus or minus 550, 31, 110, and smaller than 250, respectively.
A control moment gyroscope assembly is described for use in an astronaut maneuvering research vehicle. This vehicle (backpack) will be used by astronauts inside the orbiting Skylab for evaluation of various maneuvering systems.
A cosmic radiation dose to the Apollo 17 crew of 1.3 R was calculated from the specific activities of Na-24 in their postflight urine specimens. The specific activities of K-42, Cr-51, Co60, and Sb-124, introduced by injection into the astronauts, are extremely high in these specimens. The Fe-59 and Cs-137 levels are also reported and appear to be normal. The concentrations of Na, K, Rb, Cs, Ca, Sr, Ba, Cr, Fe, Co, Ag, Au, Zn, Cd, Hg, Sn, As, Sb, Se, Br, Sc, La, Sm, Eu, Tb, Hf, Ta, and Th were measured in urine specimens from the Apollo 17 astronauts by neutron activation analysis. Strontium, barium, gold, cadmium, lanthanum, samarium, europium, terbium, thorium, and tin are reported for the first time. The concentrations or excretion rates of bromine and the alkali metals exhibit singificantly reduced postflight levels and are generally lower than values observed for previous missions. Chromium concentrations reflect radiochromium injections.
The performance quality of movements away and approaches to an airlock by astronauts was tested during parabolic flights for weightlessness simulation. Coordination of movement, orientation and performance capacity of the astronauts were not singificantly disrupted. Observed physiological shifts are characterized by an increase in pulse and respiration rate and an increase in arterial pressure under g-forces, a gradual decrease in these indices during repeated stays in weightlessness or during the prolonged effect of it, by a reduction of the length of postrotational nystagmus and counterrotation illusions under weightless conditions.
Discussion of the astronaut's role in the Space Shuttle and its associated payload operations. It is shown that there will be a shift in the astronaut's tasks as the Shuttle system matures. The Shuttle is designed for automatic guidance, navigation, and control, and the need for active piloting will accordingly decrease. With the shift to onboard autonomous operation, the system management role will expand. Direct tasks with delivery/recovery and laboratory/observatory payloads will continue to expand throughout the Shuttle program duration through the 1980s.
On the Apollo-Soyuz mission each astronaut carried one passive dosimeter containing nuclear photographic emulsions, plastic foils, TLD chips, and neutron-activation foils for recording radiation exposure. This report is limited to the presentation of data retrieved from nuclear emulsions. Protons, most of them trapped particles encountered in numerous passes through the South Atlantic Anomaly, contributed by far the largest share to the mission dose. Their linear energy transfer (LET) spectrum was established from track and grain counts in a G.5 emulsion which is used for medium and high energies, and from ender counts in a K.2 emulsion which is used for low energies. The total mission fluence of protons was found to be equivalent to a unidirectional beam of 448,500 square centimeters. The broad spectrum was broken down into small LET intervals, which allowed for the computation of absorbed doses and dose equivalents. The totals are 51 millirad and 74 millirem. Counts of disintegration stars in K.2 emulsion are incomplete at present. While a total of 467 stars were identified, counting their prong numbers is still in progress. It was concluded that the Apollo-Soyuz astronauts' radiation exposure as such did not contain anything out of the ordinary that would seem to require special attention.
A nuclear emulsion detector known as the Apollo Light Flash Moving Emulsion Detector (ALFMED) was designed: (1) to record tracks of primary cosmic rays; (2) to provide time-of-passage information via a relative plate translation technique; (3) to provide particle trajectory information; and (4) to fit into a masklike device that could be located about the head and eyes of an astronaut. An ALFMED device was worn by an astronaut observing light flashes for 60 minutes on each of the last two Apollo missions. During the Apollo 17 experiment seventeen separate flashes were reported by the observer. With one-third of the total plate area completely analyzed, two definite correlations have been found between Z greater than 8 cosmic ray nuclei traversing an eye and the reports of visual sensations.