Search Results

The Cassini spacecraft, NASA's mission to investigate the Saturn system, has undergone an extensive thermal development test program to characterize subsystem thermal control designs. In the interest of cost and schedule, not every subsystem was subjected to thermal development testing. The majority of the testing demonstrated that the required system resources such as heater power were adequate. In the instances of the stowed magnetometer boom canister, the sun sensor head assembly, the Huygens Probe receiver front-end, the thruster cluster assembly, and radar science instrument, unexpected thermal design inadequacies were uncovered, but these problems were solved without a significant impact to system resources or thermal design robustness. Additionally, a self-regulating non-electrical heater, a radiant energy transport method, and a reverse louver were successfully demonstrated.

In August, 1995, the TOPEX/Poseidon satellite completed its third year in orbit and met its operational life requirement. The satellite TCS is performing as expected with the telemetry indicating that all components are operating within their allowable temperature ranges during normal mission modes. This paper assesses the performance of TCS from the start of the mission through 3 years in orbit at 1335 km altitude and 66.25° inclination. This orbit is in the Van Allen Belt in which few spacecraft fly. Specific attention is paid to environmental, operational, and attitude control conditions and their effects on the satellite thermal performance. The thermal telemetry data of each satellite module is discussed with respect to thermo-optical property degradation and the effects of varying orbital sun angles.

A wide range of environmental exposures, stringent payload interface conditions, a low risk requirement, low allowable heater power, constraints of a fixed price contract and aggressive schedule presented a challenge in developing the FUSE bus (spacecraft) thermal design. The bus provides power, attitude control and telemetry for the satellite, which includes the bus and instrument payload. The thermal design that evolved is remarkably self-regulating. This is attributed to the synergistic effect of a compact structure that allows cross-coupling of radiators with different exposures in addition to the advantages of a large louver. This paper discusses the design approach, key thermal control features, supporting analyses and trade studies, and how predicted results compare with requirements for the design envelope and beyond.

This paper describes the thermal vacuum (TVAC) through conductance test and model correlation results performed on the protoflight Mobile Satellite (MSAT®) L-Band Transmit (Tx) feed assembly. Very good correlation was obtained between the model and the measured results. Specifically, the correlated average temperatures for the feed array components, were all within +/- 5°C of the measured test results for all three (3) plateaus. Similar results were also obtained at 10 feed panel locations for each component. In addition, the differences in temperature gradients through the feed assembly from the cup walls to the Beam Forming Network (BFN), comparing the modelled and measured results, were less than 3°C for all three plateaus. The correlation results for the Tx feed assembly were subsequently used to update the spacecraft (S/C) L-Band antenna model.

We have conducted experiments on 16 lunar soils and 3 lunar volcanic glass samples to study the extraction of oxygen, an important resource for future lunar bases. The samples were chosen to span the range of composition and mineralogy represented in the Apollo collection. Each sample was reduced in flowing hydrogen for 3 hours at 1050°C. The dominant effect was reduction of Fe2+ (as FeO) in minerals and glass to iron metal, with concomitant release of oxygen. Oxygen extraction was strongly correlated with initial Fe2+ abundance but varied among mineral and glass phases. The experimental reduction of lunar soil and glass provides a method for assessing the oxygen production potential for sites on the lunar surface from lunar orbit. Our results show that oxygen yield from lunar soils can be predicted from knowledge of only one parameter, total iron content. This parameter can be measured from orbit by gamma ray spectrometry or multispectral imaging.

NASA has formulated a strategic plan with five major strategic enterprises: Aeronautics, Space Science, Technology, Mission to Planet Earth, and the Human Exploration and Development of Space (HEDS). Many strategic goals and objectives exist within HEDS in order to allow humans to effectively explore and develop space. Among the foremost of these goals and objectives is providing for the support of humans in their exploration of the cosmos. Future long-term exploration missions will need advanced technologies to recycle and optimize resources, monitor the characteristics of their enclosed environment, and optimize human performance. NASA has created the HEDS Advanced Human Support Technologies (HAHST) program in order to meet these challenges. This paper lays out the major missions, goals and objectives of the HAHST program, which promises to deliver many critical human support technologies over the next two decades.

As part of its integrated system test bed capability, NASA's Advanced Life Support Program has undertaken the development of a large-scale advanced life support facility capable of supporting long-duration testing of integrated, regenerative biological and physicochemical life support systems. This facility--the Advanced Life Support Human-Rated Test Facility (HRTF) is currently being built at the Johnson Space Center. The HRTF is comprised of a series of interconnected chambers with a sealed internal environment capable of supporting a test crew of four for periods exceeding one year. The life support system will consist of both biological and physicochemical components and will perform air revitalization, water recovery, food production, solid waste processing, thermal management, and integrated command and control functions. Currently, a portion of this multichamber facility has been constructed and is being outfitted with basic utilities and infrastructure.

Closed ecological life support systems incorporating plants represent the only potential for achieving self-sufficiency in an extraterrestrial biosphere. A model of input/output metabolic mass flow rates for a plant module in an Engineered Closed/Controlled EcoSystem is presented. Wheat crop was chosen as a case study for modeling metabolic mass flow rates. Coefficients for the mass flow rates, for each metabolic element, are determined per unit area of wheat production. The coefficients are utilized to compute the area of edible biomass production necessary to accommodate human food requirements. This model for computing metabolic mass flow rates can be applied for any crop under specified growing conditions.

During the STS-69 Space Shuttle flight in September, 1995, the Manipulator Position Display (MPD) and the Joint Angle Display (JAD) were used for the first time on-orbit. The title of the evaluation was Development Test Objective (DTO) 831, “Manipulator Position Display as an Aid to Remote Manipulator System (RMS) Operators.” The MPD and JAD provided hand controller input cues and situational awareness cues to assist the RMS operator. These two displays were evaluated by the STS-69 astronauts while operating the Space Shuttle's Remote Manipulator System (RMS). The display software ran on the standard Space Shuttle laptop computers, the Payload and General Support Computers (PGSC's), and the displays were viewed by the astronauts on the PGSC monitors. RMS position, attitude, joint angle, and mode data were used to derive the display cues. This paper discusses the results of this on-orbit evaluation including performance data and crew comments.

A system analysis of sources and sinks for nitrogen diluent in a closed spacecraft environment has been carried out. Methods of transporting nitrogen, free or chemically bound, into orbit and the fate of nitrogen in spacecraft wastes has been carried out. The data indicates that in a closed CELSS environment, transportation of plant nutrients and reduction of waste material to nitrogen has many advantages from a process and penalty perspective.

Rovers will play a vital role in upcoming Mars missions by enabling science activities at a wide variety of locations even kilometers away from the landing site. On-going technology development efforts at the Jet Propulsion Laboratory include the Long Range Science Rover Task which is prototyping and demonstrating rover technology capable of traversing several kilometers over the Martian surface carrying out a wide variety of science activities. This paper discusses the operational requirements for Mars science rovers and a current prototype Mars rover called Rocky 7.

A finite-difference gas adsorption computer model for CO2, H2O, and N2 on zeolite 5A is discussed. It is part of an effort to predict results, via simulation, of changing a spacecraft CO2 removal system's operational configuration. The mathematical and numerical modeling approach, with emphasis on identification and independent verification of important adsorption physics, is described. The apparatus used to obtain single and multicomponent isotherms, and the subscale packed column bench test used to derive transfer coefficients and verify the model are described. The favorable comparison of simulation and test results show the potential for predictive capability with this modeling approach.

Performance Analysis and assessment of the airflow interchange system between the mated Space Shuttle Orbiter and International Space Station (ISS) is a vital task to ensure a successful completion of the ISS assembly missions. A multi-module mated air interchange system performance computer model was developed and upgraded for evaluating the atmospheric characteristics within each habitable volume on the Orbiter and all modules of the ISS. The results from this model can be utilized to assess and determine Orbiter's interchange airflow supply capabilities, develop mated air interchange system design limitations and requirements, and predict possible mated air interchange system operating constraints during the assembly missions. The results from this performance model were also used to ensure the air interchange system operation will meet the specific environmental requirements and interface hardware design constraints.

A new configuration of centrifugal waste liquid separator is presently under development in Microtecnica. Its main feature is the single shaft configuration, which means only one motor drives both the separator sub-assy and the fan, which is unusual for this class of separator. This paper will describe all the reasons for this selection, the features of the system, the performances and the results obtained at the present stage of development.

Gas-water separation is a fundamental requirement during long term operation of manned and man-tended space systems. Two areas of specific concern are in cabin humidity and temperature control and in gas removal from cooling water loops. This paper addresses design and testing of breadboard models for a condensate separator and a gas trap. Both models are based on semi-permeable membranes as main functional elements. The breadboard designs are driven by the requirements of the COLUMBUS space station. The condensate separator shall remove heat as well as water vapour from a humid air flow. Water shall permeate through the membranes, that are separating the air from the cooling water. The gas trap shall filter gas bubbles in a water loop and release the gas from the loop. In addition it shall maintain dissolved gas levels well below saturation.

Structures for use on the Moon and/or Mars face similar requirements and design criteria despite the differences in the corresponding environmental conditions. In both cases, the internal pressure is the dominant load and, therefore, the structure is a pressure vessel. A generic inflatable module is proposed as an efficient and functional structure for a lunar/Martian base. Each module consists of thin membranes supported by an inflated framing system. Module characteristics, including component dimensions, membrane thicknesses and overall mass, are presented.

The International Space Station Alpha (ISSA) Temperature and Humidity Control (THC) subsystem has been reconfigured and tested for both Node 1 and US Laboratory modules. Each element shares conditioned air that originates in the Lab module and is distributed into either the Lab, Node 1, Mini-Pressurized Logistics Module (MPLM), or the Cupola. This “parasitic” cooling scheme was tested at the McDonnell Douglas Space System Laboratory in Huntington Beach, California, during the summer of 1995. This test involved the use of standard and nonstandard techniques of measuring air flow through a complex system of ducting. Flow balancing was achieved through a series of additional dampers and orifices throughout the system. The purpose of this paper is to review some of the air flow measurement techniques and compare some of the test results with traditional theory. Techniques used for flow balancing, and test conclusions and recommendations, are also included.

The International Space Station (ISS) Temperature and Humidity Control (THC) system has been reconfigured from the Space Station Freedom (SSF) configuration to meet new interface requirements and to implement a new “parasitic” air cooling scheme. This scheme provides Lab THC cooled air to Node 1, and more critically integrates Node 1 ports at different stages of space station assembly. A joint development test of the complex U.S. Lab and Node 1 integrated THC/IMV ducting system was conducted in the summer of 1995 at the McDonnell Douglas test facility in Huntington Beach, California. The purpose of the test was to show overall capability of the ducting system to meet basic requirements, and to provide detailed flow and pressure drop performance data for individual duct segments. This paper provides correlations of the test data with analytical data obtained from a computerized model of the THC/IMV ducting system.

The continuous development of Extravehicular Activity (EVA) spacesuit gloves has lead to an effective solution for performing EVA to date. Some aspects of the current EVA gloves have been noted to affect crew performance in the form of limited dexterity and accelerated onset of fatigue from high torque mobility joints. This in conjunction with the fact that more frequent and complex EVAs will occur with the fabrication and occupation of Space Station Freedom, suggest the need for improved spacesuit gloves. Therefore, several efforts have been conducted in the recent past to enhance the performance of the spacesuit glove. The following is a description of the work performed in these programs and their impact on the design and performance of EVA equipment. In the late 1980's and early 1990's, a spacesuit glove design was developed that focused on building a more conformal glove with improved mobility joints that could function well at a higher operating pressure.

For the determination of the solar absorptance αs and the thermal emittance ε optical methods are preferred. These optical measuring procedures are relatively exact. They also deliver information about any potential spectral selective behaviour of surfaces. However, special measuring equipment is required. Particularly if space simulation facilities are already available, the method presented in [1] appears as a suitable enrichment of the measurement methods for the determination of the thermooptical properties αs and ε. It is possible with slight technical expense to expand the usage potential of such facilities. For this paper the same test rig as in [1] is used. In a common space simulation chamber (vacuum; cryogenic shroud; solar simulator) a test item (target) is arranged. In different measuring phases the target is heated up by an integrated electrical heater or by solar irradiation. The arrangement (target / shroud) is regarded as a two node model.