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John H. Miller, Jr. (r.) TcSUH and Gemunu Gunaratne (l.), Department of Physics |
Edgar A. Bering, Ph.D., Department of Physics
This project, funded for two years by ISSO, was brought to the attention of UH researchers by Mr. Charles Armstrong of NASA-Johnson Space Center. Mr. Armstrong, among others, has become concerned about the viability of spacesuit electronics during EVA when the Orbiter is in high inclination orbit, flying belly forward. Under these circumstances, the possibility exists that large surface charges will build up on the insulating surfaces of the payload bay. ISSO researchers have been engaged in the Phase A study of instrumentation to investigate the scope of such possible hazards.
The funds obtained have been used to supervise Mr. Armstrong in preparation of a masterŐs thesis and this Phase A study. The major focus of effort during the past year has been to finalize preliminary designs for the hardware: input pre-amplification, signal amplification, range selection circuitry and display electronics. Completion of the auto-ranging system design was the last step. Mr. Armstrong devoted several months to learning how auto-ranging systems are built . In response to a refereeŐs comments on the proposal for this work, Mr. Armstrong spent several weeks expanding the proposed on-orbit science plan for the device. July 1993, Mr. Armstrong defended his thesis on "Design of a Langmuir Double Probe for Use by EVA Crewmen," and his research can form the nucleus of a proposal to NASA to conduct a Phase B study of a specific hardware design of the surface charge probe device.
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Edwin Carrasquillo M., Ph.D., Department of Chemistry
The objective of the year's research effort was to develop and implement a novel approach to probe the spectroscopy of the important HCN molecule at astrophysically significant vibrational energy content. The new approach makes use of collisions to move the molecular population into previously inaccessible ground state vibrational levels at high excitation. It combines direct overtone vibration excitation, to state-selectively prepare highly excited HCN, with a laser induced fluorescence probe via the state, to monitor the collisionally populated levels. With this method, the research project revealed extensive vibrational structure for the ground electronic state at energies between 6,000 and 10,000 cm-1 which was undetectable to the standard spectroscopic techniques at high excitation. Studies also probed previously inaccessible vibrational levels of the first excited electronic state. The characterization of the highly energized HCN molecule already achieved and the fluorescence probe capabilities developed permit detailed state-resolved study of the vibrationally hot HCN products generated in astrophysically significant exothermic reactions.
Future research will investigate reactions shown to be important in the Titan atmosphere by Voyager II and in the atmospheres of carbon rich stars. (Titan is the largest moon of the planet Saturn). The technique will also further characterize the energized HCN molecule, an important prelude for modeling planetary and stellar atmospheres (Figs. 1 and 2).
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Elbert A. King, Ph.D., Department of Geosciences and Michael G. Fahey, Lunar Technologies, Inc., Houston, Texas
The Space Exploration Initiative (SEI), established in 1989 by NASA in cooperation with the Department of Energy (DOE), and the Department of Defense (DOD), awaits the time when U.S. interest and available funding augur progress. At present, the project is not a government priority, although work completed to date suggests that research among devoted investigators will progress at a low level.
The original purposes of the effort were to establish a permanent base on the Moon and to begin the human exploration of Mars by landing a crew on the surface of that planet. Advisory committees to NASA recommended that the activities begin with a series of unmanned lunar orbiters and surface rovers, termed the "Artemis Program."
The first two missions were to be designated orbiters, designed to obtain global data coverage by a number of scientific instruments. The third mission in the program was to have landed on the lunar surface via a tele-operated/robotic rover whose total payload weight, including mobility systems and scientific instruments, would not exceed 65 kilograms . Later, Artemis rovers designed for landing on the surface of the Moon were projected to be as large as 200 kilograms.
Lunar rovers are capable of performing three primary tasks: (1) site certification for manned landing missions, (2) resource delineations, and (3) scientific data acquisition.
A broad segment of the industrial and academic communities, as well as DOE, DOD, and other NASA centers, have been solicited to propose the optimum instrument payload for the first lunar rover, should the initiative gain new impetus. Guidelines propose that all portions of the payload be small, simple, cheap, and quick. Priorities are schedule, cost, risk, and performance. Mission plans are exceedingly site specific and probably will have to await selection of the first rover landing site, which, presumably, will also be the First Lunar Outpost (FLO) manned landing site.
ISSO investigators have made the following recommendations: Because it is essential to crew safety in the First Lunar Outpost, landing site certification must have the highest priority of all Artemis unmanned rover tasks on the lunar surface. The selection of the FLO landing site near the Apollo 11 site (Tranquillity Base) or a location further south, closer to highland rocks, is recommended because of the high ilmenite contents of the rocks and regolith and the existing high resolution imagery, if the requirement for a free return trajectory is imposed as a matter of crew safety. If there is no free return mission operations requirement, then the Apollo 17 site in the valley of Taurus Littrow should also be considered. The choices of either of these previous Apollo landing sites for the FLO would avail more time for resource delineation and for the collection of scientific data by the rover. Considerable overlap is projected for both rover activities and resource delineation. Analytical requirements on the moon for both purposes can be satisfied by a modest instrument payload that can be accommodated within the given weight and support constraints. In order to gain the maximum scientific information from the rocks and regolith encountered by the rover, samples must be collected, packaged, stored, and eventually delivered to terrestrial laboratories for intense scrutiny. Analysis performed on board the rover, while possibly satisfying the requirements for resource delineation, would serve chiefly as guides in making the "collect/no collect" decision for scientific purposes.
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E.A. Bering, III, Ph.D., and J.R. Benbrook, Ph.D., Department of Physics.
Over the past six years, a rocket-based parachute-deployed low-energy X-ray pinhole camera was developed with support from the State of Texas. This camera has been designed for use in auroral studies and other applications where X-ray imaging is needed. This system detects the energy and the position of the absorption of individual X-rays in a three-inch diameter sodium iodide scintillation crystal by using a position-sensitive photomultiplier tube. The X-rays are collimated by a 1 cm2 entrance hole, two inches above the scintillator, to form a pinhole camera. A "color" image can be built up by appropriately summing the responses to the individual photons.
Two new phototubes, manufactured by Hammamatsu Corp., were purchased to replace old tubes destroyed during environmental testing. During thrust axis vibration testing of the payload in February, 1993, the new phototube failed. Plans to fly the payload in March 1993 were scrubbed. The payload has since been modified to include shock mountings for camera components.
A mock-up of the camera will be tested late in the summer of 1993 to determine whether vibration isolation is sufficient to warrant proceeding with the testing of the one remaining phototube. If so, the payload will be assembled, calibrated, and flow to NASA/Wallops Island for testing early in fall 1993. If the payload survives testing, it will be flown during the winter auroral season from Poker Flat, Alaska.
Scientific results from the expedition will be published as soon as possible after the flight. If, as expected, the instrument forms interesting images of the X-ray aurora, a proposal will be submitted to NASA for further auroral flights to build a database comparing the structure of the energetic component of auroral precipitation to the structure of the low energy component.
Contents
ISSO -- Institute for Space Systems Operations
1992-1993 Annual Report
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