O. Manuel Uy

Polymer based lanthanide luminescent sensors for the detection of nerve agents

Several devices are being constructed to measure and detect the nerve agents Sarin and Soman. The devices function by selectively binding the phosphonate hydrolysis products to a luminescent functionality-imprinted copolymer. The copolymers possess a securely bound luminescent lanthanide ion, such as Eu 3 + , in a coordination complex that has been templated for the chemical functionality resulting from the hydrolysis of Sarin and Soman but has had a weakly bound anion substituted by mass action. The instrumental support for the device is being designed to monitor the change that occurs in the luminescence spectrum of the lanthanide when the analyte is coordinated. The ligand field shifted luminescence of the lanthanide is excited by a compact laser and monitored via optical fiber by either a filter photometer or a monochromator. Miniaturization will be applied to each of the lab bench components to produce a field portable device that will potentially be comparable in size to a pH meter. Initial results using an Ar ion laser excitation source providing 0.3 mW at 465.7 nm yield a limit of detection of 125 ppt. The chemical and spectroscopic selectivity of this device are being combined to reduce the likelihood of false positive analyses.

Quartz crystal microbalance (QCM) flight measurements of contamination on the MSX satellite

The midcourse space experiment (MSX) satellite was launched into a 903 Km, 99.4-deg orbit April 24, 1996. It carries imaging spectrometers and radiometers that operate in the UV, visible, and infrared spectral ranges. In addition, it carries several contamination measuring instruments that are being used to characterize the contamination environment on, in, and around the satellite. Five are quartz crystal microbalances (QCMs), four of which are temperature- controlled (TQCMs). They are located on various external surfaces of the spacecraft and are operating at minus 40 degrees Celsius to minus 50 degrees Celsius to measure the condensation of silicone and organic molecules. One is a cryogenic quartz crystal microbalance (CQCM) which is located adjacent to the SPIRIT III infrared cryogenic telescope primary mirror. Its temperature followed the mirror which cooled from 28 to 20 K during the first week of operation. All QCMs recorded deposition in the 10 - 20 ng/cm

Contamination experiments in the Midcourse Space Experiment (MSX) satellite

2)-day (1-2 angstrom/day) range. Thermo-gravimetric analyses on the QCMs provided insight into the amount and species of contaminants condensed. Data from the QCMs and other instruments in the contamination experiment (CE) suite played an important role in determining when it was safe to open covers on some of the optical instruments.

An external sensor for instantaneous measurement of the internal temperature in lithium-ion rechargeable cells

The Midcourse Space Experiment (MSX) satellite is a space-based sensor platform primarily designed to collect data on the phenomenology of target detection and tracking. Because of the possible deleterious effect of contamination on these sensors, a suite of contamination monitoring instruments are also included in the satellite. These instruments are the Total Pressure Sensor (TPS), the Contamination Experiment Mass Spectrometer (CEMS), the Ion Mass Spectrometer (IMS), the Cryogenic Quartz Crystal Microbalance (CQCM), four Temperature-controlled Quartz Crystal Microbalance (TQCM), the Xenon Flashlamp Experiment (XFE), the Krypton Flashlamp Experiment (KFE) and the Spirit III Mirror Cleaning Experiment (SMCE). The philosophy of Contamination Experiment (CE), its calibration and testing, modeling and the data to be collected will be discussed.

Flashlamp measurement of the MSX particulate environment

Based on a four-probe electrical measurement, we have developed a Battery Internal Temperature Sensor. BITS, unlike a surface-mounted thermocouple, provides a direct measure of the internal temperature. We have demonstrate in several different rechargeable lithium-ion cells ranging in capacity from 2- to 50-Ah, the existence of an intrinsic relationship between a cells internal temperature and a readily measurable electrical parameter. Today, container rupture and fire are the most detrimental consequences of thermal runaway in rechargeable Li-ion cells. Although storing or operating Li-ion cells in high-temperature environments is not advisable, high internal temperature has a greater potential to initiate catastrophic events. Measuring the environmental temperature at any proximity to the surface of the cell is insufficient to know or intervene with fast-rising internal heat. For example, monitoring internal temperature in real time has direct relevance to the thermal runaway caused by external and internal short circuits that may have no relevance to the external temperature. Yet, until now, there has been no simple technique to monitor the internal temperature of a single cell or multiple cells in Li-ion batteries. BITS, developed by the Johns Hopkins University Applied Physics Laboratory, is a miniature instrument, with demonstrated capability to measure and report internal temperature of individual cells in a multi-cell battery pack at the rate of 200-ms/cell.

Total pressure sensor results from the early operations phase of the MSX mission

The xenon flashlamp is one of a suite of instruments that monitor the particulate and gaseous contamination environments of the midcourse space experiment (MSX) spacecraft. The near-field particulate measurement comprises the high intensity xenon flashlamp that illuminates a volume of space in the field of view of the UVISI wide field of view visible imager (UVISI IVW). Radiation scattered by illuminated contaminant particles is imaged by the IVW. The intensity of the radiation is related to a particles size and composition. The particles track yields information about its velocity and trajectory. From ground calibration data we estimate a sensitivity to detect particles smaller than 1 micrometer and to determine cross-field velocities from 1 mm/sec to 50 m/sec. The visible radiation measurement of the particulate environment provided by the xenon flashlamp and UVISI IVW is complemented by multiband IR, UV, and visible measurements by other MSX sensors. The early mission data from this experiment will quantify the relationship between ground contamination control measures, the on-orbit contamination environment, and the performance history of on-orbit sensors.

Optical measurement of the MSX local H2O density

The total pressure sensor (TPS) is one of ten contamination sensors aboard the midcourse space experiment (MSX) satellite. The TPS measures both the natural and spacecraft induced pressure environments. This paper presents a first look at the TPS data from the early operations phase of the MSX mission. Flight data are show to be in good agreement with the external contamination model predictions for MSX. TPS fluctuations are shown to be consistent with the venting characteristics of the Spirit III cryogenic cover. Data are presented which characterize and confirm the tumbling nature of the receding Spirit III cover upon its release. Finally, flight data over an orbital period are shown to conform to a bimodal pressure profile.

Long-term observations of the particle environment surrounding the MSX spacecraft

The krypton radiometer (KR) is one of a suite of instruments that monitor the gaseous and particulate contamination environments of the midcourse space experiment (MSX) spacecraft. The krypton radiometer measures the local water density in a volume of space approximately 50 cm from the spacecraft near its +X/+Y/+Z corner. The instrument comprises an array of krypton VUV lines source lamps that dissociate water and a near UV radiometer that detects the chemiluminescence from the OH dissociation products. Ground calibrations indicate that the instrument has sufficient sensitivity to detect water densities as low as 1.5 multiplied by 107 molecules cm-3. Water is the primary outgassing species during the early part of a spaceflight. Water deposition is also a particular concern to cryogenic sensors, such as the spatial infrared imaging telescope III (SPIRIT III) on this spacecraft. As the mission progresses, we will correlate the KR measurements of the water density with measurements by the neutral mass spectrometer, total pressure sensor and cryogenic quartz crystal microbalance. Using the MSX external contamination model we will create a complete description of the MSX water environment including outgassing, return flux and deposition, and effects.

Measurement of long-term outgassing from the materials used on the MSX spacecraft

We present a summary of the particle environment surrounding the Midcourse Space Experiment (MSX) satellite after 32 months on orbit, including two discrete particle releases produced by micrometeoroid or debris impact. We report on the characteristics of that environment, including particle occurrence rates, velocities, size distributions and trends in the environment. To our knowledge, the long term particle contamination observations that we have made on MSX are the first of their kind. The particle occurrence rate decreased steadily during the first year on orbit, but then remained at a constant level after 32 months on orbit. Our estimate of the total number of particles on the spacecraft surfaces at launch. We conclude that environmental effects such as UV, radiation, thermal cycling, and micrometeoroid impacts are a significant and continuing source of particles on orbit.

Optical effects of condensates on cryogenic mirrors for the Midcourse Space Experiment (MSX)

The Midcourse Space Experiment (MSX) spacecraft was specifically designed and processed to minimize contamination. This spacecraft represents a best case scenario of spacecraft induced environment. The contamination instrument suite consisted of 10 sensors for monitoring the gaseous and particulate environment. The Total Pressure Sensor (TPS) has continuously measured the ambient local pressure surrounding MSX since its launch on April 24, 1996. The sensors primary goal was to monitor the early mission (less than one week) ambient pressure surrounding the spacecrafts optical telescopes and to indicate when environmental conditions were acceptable for opening the protective covers. However, the instrument has illustrated that it is quite robust and has successfully measured the long-term decay of the pressure environment. The primary constituent of the atmosphere is water outgassed from the thermal blankets of the spacecraft. The water-induced environment was expected to rapidly decay over the first few months to levels more closely approaching the natural environment. The data generally shows decay toward this level, however, the pressure is quite variable with time and can be influenced by discrete illumination and spacecraft orbital events. Several experiments conducted yearly indicate that the thermal blankets retain significant quantities of water. The local pressure due to water vapor is shown to increase by a factor of 100 from direct solar illumination. Moreover, the multi-layer construction of the blankets causes them to form a deep reservoir that continues to be a source of water vapor 3+ years into the mission. We will present pressure data from several experiments, each separated by one orbital year, that exhibit these water vapor induced pressure busts. The decay and longevity of these bursts will also be discussed.