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Long duration exposure facility post-flight thermal analysis, part 2

Results of the post-flight thermal analysis for the Long Duration Exposure Facility (LDEF) mission are presented. The LDEF mission thermal analysis was verified by comparing the thermal model results to flight data from the LDEF Thermal Measurements System (THERM). Post-flight calculated temperature uncertainties have been reduced to under +/- 18 F from the pre-flight uncertainties of +/- 40 F. The THERM consisted of eight temperature sensors, a shared tape recorder, a standard LDEF flight battery, and an electronics control box. The temperatures were measured at selected locations on the LDEF structure interior during the first 390 days of flight and recorded for post-flight analysis. After the LDEF retrieval from Space on 12 Jan. 1990, the tape recorder was recovered from the spacecraft and the data reduced for comparison to the LDEF predicted temperatures. The LDEF mission temperatures were calculated prior to the LDEF deployment on 7 Apr. 1980, and updated after the LDEF retrieval with the following actual flight parameter data: thermal fluxes, spacecraft attitudes, thermal coatings degradation, and contamination effects. All updated data used for calculation of post-flight temperatures is also presented in this document.

Berrios, William M.↗

Power systems for the Mars Environmental Survey (MESUR) Mission

Mars Environmental Survey Mission (MESUR) is intended to be a low cost, near term mission to study the chemical composition of Martian surface, structure and circulation of Mars' atmosphere, and the structure and dynamics of Mars' interior. To meet the science objectives of the mission, a network of 16 landers will be placed at various latitudes and longitudes of Mars. The paper identifies various options for powering the landers and lists the attributes of each option. The current strategy is to precede the lander launch and deployment with an engineering demo mission called the Pathfinder which would demonstrate the landing strategy and the engineering subsystems. The paper briefly describes the challenges involved in the power system development for the Pathfinder mission.

Shirbacheh, Mike↗

Zero to Integration in Eight Months, the Dawn Ground Data System Engineering Challange

The Dawn Project has presented the Ground Data System (GDS) with technical challenges driven by cost and schedule constraints commonly associated with National Aeronautics and Space Administration (NASA) Discovery Projects. The Dawn mission consists of a new and exciting Deep Space partnership among: the Jet Propulsion Laboratory (JPL), responsible for project management and flight operations; Orbital Sciences Corporation (OSC), spacecraft builder and responsible for flight system test and integration; and the University of California, at Los Angeles (UCLA), responsible for science planning and operations. As a cost-capped mission, one of Dawn s implementation strategies is to leverage from both flight and ground heritage. OSC's ground data system is used for flight system test and integration as part of the flight heritage strategy. Mission operations, however, are to be conducted with JPL s ground system. The system engineering challenge of dealing with two heterogeneous ground systems emerged immediately. During the first technical interchange meeting between the JPL s GDS Team and OSC's Flight Software Team, August 2003, the need to integrate the ground system with the flight software was brought to the table. This need was driven by the project s commitment to enable instrument engineering model integration in a spacecraft simulator environment, for both demonstration and risk mitigation purposes, by April 2004. This paper will describe the system engineering approach that was undertaken by JPL's GDS Team in order to meet the technical challenge within a non-negotiable eight-month schedule. Key to the success was adherence to an overall systems engineering process and fundamental systems engineering practices: decomposition of the project request into manageable requirements; definition of a structured yet flexible development process; integration of multiple ground disciplines and experts into a focused team effort; in-process risk management; and aggregation of the intermediate products to an integrated final product. In addition, this paper will highlight the role of lessons learned from the integration experience. The lessons learned from an early GDS deployment have served as the foundation for the design and implementation of the Dawn Ground Data System.

systems engineering↗

Ground-Based High Spectral Resolution Lidar Observation of Aerosol Vertical Distribution in the Summertime Southeast United States

As part of the Southeast United States-based Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS), and collinear with part of the Southeast Atmosphere Study, the University of Wisconsin High Spectral Resolution Lidar system was deployed to the University of Alabama from 19 June to 4 November 2013. With a collocated Aerosol Robotic Network (AERONET) sun photometer, a nearby Chemical Speciation Network (PM2.5) measurement station, and near daily ozonesonde releases for the August-September SEAC4RS campaign, the site allowed the regions first comprehensive diurnal monitoring of aerosol particle vertical structure. A 532nm lidar ratio of 55 sr provided good closure between aerosol backscatter and AERONET (aerosol optical thickness, AOT). A principle component analysis was performed to identify key modes of variability in aerosol backscatter. ''Fair weather'' days exhibited classic planetary boundary layer structure of a mixed layer accounting for approx. 50% of AOT and an entrainment zone providing another 25%. An additional 5-15% of variance is gained from the lower free troposphere from either convective detrainment or frequent intrusions of western United States biomass burning smoke. Generally, aerosol particles were contained below the 0 C level, a common level of stability in convective regimes. However, occasional strong injections of smoke to the upper troposphere were also observed, accounting for the remaining 10-15% variability in AOT. Examples of these common modes of variability in frontal and convective regimes are presented, demonstrating why AOT often has only a weak relationship to surface PM2.5 concentration.

HSRL↗

Numerical model of solar dynamic radiator for parametric analysis

Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. The SD module rejects waste heat from the power conversion cycle to space through a pumped-loop, multi-panel, deployable radiator. The baseline radiator configuration was defined during the Space Station conceptual design phase and is a function of the state point and heat rejection requirements of the power conversion unit. Requirements determined by the overall station design such as mass, system redundancy, micrometeoroid and space debris impact survivability, launch packaging, costs, and thermal and structural interaction with other station components have also been design drivers for the radiator configuration. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations. A brief description and discussion of the numerical model, it's capabilities and limitations, and results of the parametric studies performed is presented.

Rhatigan, Jennifer L.↗

Pucksat Payload Carrier

There is an ever-expanding need to provide economical space launch opportunities for relatively small science payloads. To address this need, a team at NASA's Goddard Space Flight Center has designed the Pucksat. The Pucksat is a highly versatile payload carrier structure compatible for launching on a Delta II two-stage vehicle as a system co-manifested with a primary payload. It is also compatible for launch on the Air Force Medium Class EELV. Pucksat's basic structural architecture consists of six honeycomb panels attached to six longerons in a hexagonal manner and closed off at the top and bottom with circular rings. Users may configure a co-manifested Pucksat in a number of ways. As examples, co-manifested configurations can be designed to accommodate dedicated missions, multiple experiments, multiple small deployable satellites, or a hybrid of the preceding examples. The Pucksat has fixed lateral dimensions and a downward scaleable height. The dimension across the panel hexagonal flats is 62 in. and the maximum height configuration dimension is 38.5 in. Pucksat has been designed to support a 5000 lbm primary payload, with the center of gravity located no greater than 60 in. from its separation plane, and to accommodate a total co-manifested payload mass of 1275 lbm.

Milam, M. Bruce↗

Analysis and Ground Testing for Validation of the Inflatable Sunshield in Space (ISIS) Experiment

The Next Generation Space Telescope (NGST) design requires a large sunshield to protect the large aperture mirror and instrument module from constant solar exposure at its L2 orbit. The structural dynamics of the sunshield must be modeled in order to predict disturbances to the observatory attitude control system and gauge effects on the line of site jitter. Models of large, non-linear membrane systems are not well understood and have not been successfully demonstrated. To answer questions about sunshield dynamic behavior and demonstrate controlled deployment, the NGST project is flying a Pathfinder experiment, the Inflatable Sunshield in Space (ISIS). This paper discusses in detail the modeling and ground-testing efforts performed at the Goddard Space Flight Center to: validate analytical tools for characterizing the dynamic behavior of the deployed sunshield, qualify the experiment for the Space Shuttle, and verify the functionality of the system. Included in the discussion will be test parameters, test setups, problems encountered, and test results.

Lienard, Sebastien↗

Opening Loads Analyses for Various Disk-Gap-Band Parachutes

Detailed opening loads data is presented for 18 tests of Disk-Gap-Band (DGB) parachutes of varying geometry with nominal diameters ranging from 43.2 to 50.1 ft. All of the test parachutes were deployed from a mortar. Six of these tests were conducted via drop testing with drop test vehicles weighing approximately 3,000 or 8,000 lb. Twelve tests were conducted in the National Full-Scale Aerodynamics Complex 80- by 120-foot wind tunnel at the NASA Ames Research Center. The purpose of these tests was to structurally qualify the parachute for the Mars Exploration Rover mission. A key requirement of all tests was that peak parachute load had to be reached at full inflation to more closely simulate the load profile encountered during operation at Mars. Peak loads measured during the tests were in the range from 12,889 to 30,027 lb. Of the two test methods, the wind tunnel tests yielded more accurate and repeatable data. Application of an apparent mass model to the opening loads data yielded insights into the nature of these loads. Although the apparent mass model could reconstruct specific tests with reasonable accuracy, the use of this model for predictive analyses was not accurate enough to set test conditions for either the drop or wind tunnel tests. A simpler empirical model was found to be suitable for predicting opening loads for the wind tunnel tests to a satisfactory level of accuracy. However, this simple empirical model is not applicable to the drop tests.

Cruz, J. R.↗

Fabrication end Deployment Testing of Meter Solar Sail Quadrants for a Scaleable Square Solar Sail Ground Test System

In order for solar sail propulsion technologies to be considered as a viable option for a wide range of near term practical missions a predictable, stable, reliable, manufactureable, scaleable, and cost effective system must be developed and tested first on earth and then on orbit. The design and development of a Scaleable Square Solar Sail System (S^4) is well underway a t AEC-Able Engineering Co. Inc., and the design and production of the Solar Sails for this system is being carried out by SRS Technologies. In April and May of 2004 a single quadrant 10-meter system was tested at NASA LARC's vacuum chamber and a four quadrant 20-meter system has been designed and built for deployment and testing in the Spring of 2005 at NASA/Glenn Research Center's Plumb Brook Facility. SRS has developed an effective and efficient design for triangular sail quadrants that are supported are three points and provide a flat reflective surface with a high fill factor. This sail design is robust enough for deployments in a one atmosphere, one gravity environment and incorporates several advanced features including adhesiveless seaming of membrane strips, compliant edge borders to allow for film membrane cord strain mismatch without causing wrinkling and low mass (3% of total sail mass) ripstop. This paper will outline the sail design and fabrication process, the lessons learned and the resulting mature production, packaging and deployment processes that have been developed. It will also highlight the scalability of the equipment and processes that were developed to fabricate and package the sails. Based on recent experience, SRS is confidant that flight worthy solar sails in the 40-120-meter size range with areal density in the 4-5g/sq m (sail minus structure) range can be produced with existing technology. Additional film production research will lead to further reductions in film thickness to less than 1 micron enabling production of sails with areal densities as low as 20 g/sq m using the current design resulting in a system areal density of as low as 5.3g/sq m. These areal densities are low enough to allow nearly all of the Solar Sail missions that have been proposed by the scientific community and the fundamental technology required to produce these sails has been demonstrated on the ground test sails that have recently been built. These demonstrations have shown that the technology is mature enough to build sails needed to support critical science missions. Solar Sails will be an enabling technology for NASA's Vision for Space Exploration by allowing communication satellite orbits that can maintain continuous communication with the polar regions of the Moon and Mars and to support solar weather monitoring to provide early warning of solar flares and storms that could threaten the safety of astronauts and other spacecraft.

Laue, Greg↗

Mars Greenhouses: Concepts and Challenges. Proceedings from a 1999 Workshop

Topic covered include :Plants on Mars: On the Next Mission and in the Long Term Future; Bubbles in the Rocks: Natural and Artificial Caves and Cavities as Like Support Structures; Challenges for Bioregenerative Life Support on Mars; Cost Effectiveness Issues; Low Pressure Systems for Plant Growth; Plant Responses to Rarified Atmospheres; Can CO2 be Used as a Pressurizing Gas for Mars Greenhouses?; Inflatable Habitats Technology Development; Development of an Inflatable Greenhouse for a Modular Crop Production System; Mars Inflatable Greenhouse Workshop; Design Needs for Mars Deployable Greenhouse; Preliminary Estimates of the Possibilities for Developing a Deployable Greenhouse for a Planetary Surface Mars; Low Pressure Greenhouse Concepts for Mars; Mars Greenhouse Study: Natural vs. Artificial Lighting; and Wire Culture for an Inflatable Mars Greenhouse and Other Future Inflatable Space Growth Chambers.

Wheeler, Ray M.↗

Haughton-Mars Project/NASA 2006 Lunar Medical Contingency Simulation: Equipment and Methods for Medical Evacuation of an Injured Crewmember

Introduction: Achieving NASA's Space Exploration Vision scientific objectives will require human access into cratered and uneven terrain for the purpose of sample acquisition to assess geological, and perhaps even biological features and experiments. Operational risk management is critical to safely conduct the anticipated tasks. This strategy, along with associated contingency plans, will be a driver of EVA system requirements. Therefore, a medical contingency EVA scenario was performed with the Haughton-Mars Project/NASA to develop belay and medical evacuation techniques for exploration and rescue respectively. Methods: A rescue system to allow two rescuer astronauts to evacuate one in incapacitated astronaut was evaluated. The systems main components were a hard-bottomed rescue litter, hand-operated winch, rope, ground picket anchors, and a rover-winch attachment adapter. Evaluation was performed on 15-25deg slopes of dirt with embedded rock. The winch was anchored either by adapter to the rover or by pickets hammered into the ground. The litter was pulled over the surface by rope attached to the winch. Results: The rescue system was utilized effectively to extract the injured astronaut up a slope and to a waiting rover for transport to a simulated habitat for advanced medical care, although several challenges to implementation were identified and overcome. Rotational stabilization of the winch was found to be important to get maximize mechanical advantage from the extraction system. Discussion: Further research and testing needs to be performed to be able to fully consider synergies with the other Exploration surface systems, in conducting contingency operations. Structural attachment points on the surface EVA suits may be critical to assist in incapacitated evacuation. Such attach points could be helpful in microgravity incapacitated crewmember transport as well. Wheeled utility carts or wheels that may be attachable to a litter may also aid in extraction and transport. Utilizing parts of the rover (e.g. seats) to deploy as a litter may be considered. Testing in simulated 1/6-g to determine feasibility of winch operation and anchor establishment will further reduce implementation uncertainties.

Chappell, S. P.↗

Space Technology 5 (ST-5) Multipoint Observations of Temporal and Spatial Variability of Field-Aligned Currents

Space Technology 5 (ST-5) is a three micro-satellite constellation deployed into a 300 x 4500 km, dawn-dusk, sun-synchronous polar orbit from March 22 to June 21, 2006, for technology validations. In this paper, we present a study of the temporal variability of field-aligned currents using multi-point magnetic field measurements from ST5. The data demonstrate that mesoscale current structures are commonly embedded within large-scale field-aligned current sheets. The meso-scale current structures are very dynamic with highly variable current density and/or polarity in time scales of about 10 min. They exhibit large temporal variations during both quiet and disturbed times in such time scales. On the other hand, the data also shown that the time scales for the currents to be relatively stable are about 1 min for meso-scale currents and about 10 min for large scale current sheets. These temporal features are obviously associated with dynamic variations of their particle carriers (mainly electrons) as they respond to the variations of the parallel electric field in auroral acceleration region. The characteristic time scales for the temporal variability of meso-scale field-aligned currents are found to be consistent with those of auroral parallel electric field.

Le, Guan↗

Space Technology 5 (ST-5) Observations of Field-Aligned Currents: Temporal Variability

Space Technology 5 (ST-5) is a three micro-satellite constellation deployed into a 300 x 4500 km, dawn-dusk, sun-synchronous polar orbit from March 22 to June 21, 2006, for technology validations. In this paper, we present a study of the temporal variability of field-aligned currents using multi-point magnetic field measurements from STS. The data demonstrate that masoscale current structures are commonly embedded within large-scale field-aligned current sheets. The meso-scale current structures are very dynamic with highly variable current density and/or polarity in time scales of about 10 min. They exhibit large temporal variations during both quiet and disturbed times in such time scales. On the other hand, the data also shown that the time scales for the currents to be relatively stable are about I min for meso-scale currents and about 10 min for large scale current sheets. These temporal features are obviously associated with dynamic variations of their particle carriers (mainly electrons) as they respond to the variations of the parallel electric field in auroral acceleration region. The characteristic time scales for the temporal variability of meso-scale field-aligned currents are found to be consistent with those of auroral parallel electric field.

Le, Guan↗

Solar-power for Deep Space Science Missions

Solar power systems have enabled dazzling planetary science missions to much of the Solar System. This chapter outlines the types of solar array structures that have been used on U.S.-led robotic planetary science missions since the beginning of the space age, including several in development for future launch. The first solar-powered spacecraft employed body-mounted solar cells but designs quickly moved to extended panels to generate more electrical power. Early “paddle” designs were replaced by deployable twin rectangular “wings” which are still common in science missions and nearly ubiquitous in commercial telecommunications satellites. The increasing complexity of science missions investigating the nature of the space environment drove the development of the solar-powered satellites from the very beginning, and unique mission requirements to explore ever more distant and harsher regions of our solar system continue to drive innovations in spacecraft design, including solar arrays. This general progression to ever larger solar arrays to power ever more sophisticated spacecraft in ever harsher environments, punctuated by missions that emphasize lower cost and complexity, is a pattern that began in the 1960s and continues to this day. This chapter describes the solar array configurations used on deep space missions, with an emphasis on NASA’s planetary science missions, including specific design requirements that led to individual design selections. Future trends are also described.

Carolyn R Mercer↗

Effective conductivity of wire mesh reflectors for space deployable antenna systems

This report summarizes efforts to characterize the measurement of conductive mesh and smooth surfaces using proximity measurements for a dielectric resonator. The resonator operates in the HEM11 mode and is shown to have an evanescent field behavior in the vicinity of the sample surface, raising some question to the validity of measurements requiring near normal incidence on the material. In addition, the slow radial field decay outside of the dielectric resonator validates the sensitivity to the planar supporting structure and potential radiation effects. Though these concerns become apparent along with the sensitivity to the gap between the dielectric and the material surface, the basic concept of the material measurement using dielectric resonators has been verified for useful comparison of material surface properties. The properties, particularly loss, may be obtained by monitoring the resonant frequency along with the resonator quality factor (Q), 3 dB bandwidth, or the midband transmission amplitude. Comparison must be made to known materials to extract the desired data.

Davis, William A.↗

Large Deployable Reflector (LDR) - A concept for an orbiting submillimeter-infrared telescope for the 1990s

The history and background of the Large Deployable Reflector (LDR) are reviewed. The results of the June 1982 Asilomar (CA) workshop are incorporated into the LDR science objectives and telescope concept. The areas where the LDR may have the greatest scientific impact are in the study of star formation and planetary systems in the own and nearby galaxies and in cosmological studies of the structure and evolution of the early universe. The observational requirements for these and other scientific studies give rise to a set of telescope functional requirements. These, in turn, are satisfied by an LDR configuration which is a Cassegrain design with a 20 m diameter, actively controlled, segmented, primary reflector, diffraction limited at a wavelength of 30 to 50 microns. Technical challenges in the LDR development include construction of high tolerance mirror segments, surface figure measurement, figure control, vibration control, pointing, cryogenics, and coherent detectors. Project status and future plans for the LDR are discussed.

Swanson, P. N.↗

The effect of direct and reflected radiation on the temperatures of space structures

As an orbiting structure passes from the bright side to the dark side of the earth, substantial differences in surface heating may take place due to direct sunlight and albedo. Most structures are built of convex curved elements to spread out the reflected energy. A change in the shortwave absorptivity and emissivity maintains the temperature of electronic components within a narrow range. Temperature extremes may also be reduced by the use of thermal capacity of the system or by shielding the surface from direct sunlight. For an instrument deployed from a Shuttle, a temperature must be established for it in the cargo bay before deployment. The effect of obstructed views by surfaces such as the Shuttle arm complicates solar flux computations because of the object's mobility. For typical orbits, the earth's albedo and the direct long wavelength radiation may be as much as 30 percent of the direct solar flux. Irradiation due to direct and reflected solar, long wave radiation and reflected radiation from earth, and from Shuttle surfaces is largely dependent on the specular reflection from the radiators as the Shuttle rolls and its surfaces block the sun. Through a judicious choice of surface properties, thermal capacitance and orbit attitude programming, the temperature response of a system can be controlled.

Emery, A. F.↗

Report of the Asilomar 3 LDR Workshop

The conclusions and recommendations of the workshop held to study technology development issues critical to the Large Deployable Reflector (LDR) are summarized. LDR is to be a dedicated, orbiting, astronomical observatory, operating at wavelengths from 30 to 1000 microns, a spectral region where the Earth's atmosphere is almost completely opaque. Because it will have a large, segmented, passively cooled aperture, LDR addresses a wide range of technology areas. These include lightweight, low cost, structural composite reflector panels, primary support structures, wavefront sensing and adaptive optics, thermal background management, and integrated vibration and pointing control systems. The science objectives for LDR present instrument development challenges for coherent and direct arrayed detectors which can operate effectively at far infrared and submillimeter wavelengths, and for sub-Kelvin cryogenic systems.

Mahoney, M. J.↗