Engineering topics
Carter, D.
Publications and source records attributed to Carter, D..
Measuring Atmospheric Gas Using Small Satellites (Final Report)
The research focused on demonstrating that a small satellite (< 10 kg) is able to provide useable data in support of stratospheric circulation and broader atmospheric measurement generally thought to required large, lengthy and high cost space programs. The research goals targeting enabling CubeSats to serve as science platforms including low-cost communication infrastructure, science enabling solar panels and a ruggedized small form factor science instrument were highly successful with demonstrated on-orbit results. The collection of science data on-orbit was not successful due to a high tumbling rate impacted to the spacecraft at time of release on orbit, preventing reliable solar charging and leading to premature ending of the mission. The successes acquired on orbit will act as a springboard for further research and space projects at LLNL. Several research groups (both private and government) have expressed interest in the area of this research that proved successful such as the solar panels and iridium crosslink as well as the LLNL developed CubeSat standard.
Lessons Learned from Flight Observations of the GOES-R Magnetometer
The Geostationary Operational Environmental Satellite (GOES)-16 observatory was launched on 19 November 2016. During daily on-orbit operations, shadowing of the inboard magnetometer sensor unit occurs due to spacecraft geometry and solar angle. Throughout the shadowing periods of the inboard magnetometer, anomalous excursions of 20 nanotesla (nT) are observed. In addition to the excursions during shadow events, the measurement difference between the inboard and outboard magnetometer varies over the day, indicating erroneous measurements by one or both magnetometers. In addition, based on the deployment rotations, the zero offsets of the X and Y axes were found to be significantly different, ~30nT, from ground calibration data. Because of these observations, an extensive root cause investigation was undertaken to correct the magnetometer system for the next spacecraft in the GOES-R series. This paper documents the efforts of that activity and the lessons learned as a result of the investigation.
Lessons Learned from Flight Observations of the GOES-R Magnetometer
The Geostationary Operational Environmental Satellite (GOES)-16 observatory was launched on 19 November 2016. During daily on-orbit operations, shadowing of the inboard magnetometer sensor unit occurs due to spacecraft geometry and solar angle. Throughout the shadowing periods of the inboard magnetometer, anomalous excursions of 20 nanotesla (nT) are observed. In addition to the excursions during shadow events, the measurement difference between the inboard and outboard magnetometer varies over the day, indicating erroneous measurements by one or both magnetometers. In addition, based on the deployment rotations, the zero offsets of the X and Y axes were found to be significantly different, ~30nT, from ground calibration data. Because of these observations, an extensive root cause investigation was undertaken to correct the magnetometer system for the next spacecraft in the GOES-R series. This paper documents the efforts of that activity and the lessons learned as a result of the investigation.
Future Evolution of NASA's SLR and VLBI Networks
Over the first half of this decade the NASA Space Geodesy Program is planning a major transformation of its existing (Satellite Laser Ranging) SLR network of stations and also further evolutionary changes to its network of (Very Long Base Interferometry) VLBI stations. These network changes will be made to meet the ever more demanding requirements of the earth and space science programs that these networks support while seeking through automation and electronic data communications to increase efficiency and decrease cost of operations and maintenance. The major aspects of the NASA plan will be outlined and the benefits to the scientific community will be addressed.
The transition of GTDS to the Unix workstation environment
Future Flight Dynamics systems should take advantage of the possibilities provided by current and future generations of low-cost, high performance workstation computing environments with Graphical User Interface. The port of the existing mainframe Flight Dynamics systems to the workstation environment offers an economic approach for combining the tremendous engineering heritage that has been encapsulated in these systems with the advantages of the new computing environments. This paper will describe the successful transition of the Draper Laboratory R&D version of GTDS (Goddard Trajectory Determination System) from the IBM Mainframe to the Unix workstation environment. The approach will be a mix of historical timeline notes, descriptions of the technical problems overcome, and descriptions of associated SQA (software quality assurance) issues.
Protein crystal growth results from the United States Microgravity Laboratory-1 mission
Protein crystal growth experiments have been performed by this laboratory on 18 Space Shuttle missions since April, 1985. In addition, a number of microgravity experiments also have been performed and reported by other investigators. These Space Shuttle missions have been used to grow crystals of a variety of proteins using vapor diffusion, liquid diffusion, and temperature-induced crystallization techniques. The United States Microgravity Laboratory - 1 mission (USML-1, June 25 - July 9, 1992) was a Spacelab mission dedicated to experiments involved in materials processing. New protein crystal growth hardware was developed to allow in orbit examination of initial crystal growth results, the knowledge from which was used on subsequent days to prepare new crystal growth experiments. In addition, new seeding hardware and techniques were tested as well as techniques that would prepare crystals for analysis by x-ray diffraction, a capability projected for the planned Space Station. Hardware that was specifically developed for the USML-1 mission will be discussed along with the experimental results from this mission.
Recent results and new hardware developments for protein crystal growth in microactivity
Protein crystal growth experiments have been performed on 16 space shuttle missions since April, 1985. The initial experiments utilized vapor diffusion crystallization techniques similar to those used in laboratories for earth-based experiments. More recent experiments have utilized temperature induced crystallization as an alternative method for growing high quality protein crystals in microgravity. Results from both vapor diffusion and temperature induced crystallization experiments indicate that proteins grown in microgravity may be larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on earth.
Preliminary investigations of protein crystal growth using the Space Shuttle
Four preliminary Shuttle experiments are described which have been used to develop prototype hardware for a more advanced system that will evaluate effects of gravity on protein crystal growth. The first phase of these experiments has centered on the development of micromethods for protein crystal growth by vapor-diffusion techniques (using a space version of the hanging-drop method) and on dialysis using microdialysis cells. Results suggest that the elimination of density-driven sedimentation can effect crystal morphology. In the dialysis experiment, space-grown crystals of concanavalin B were three times longer and 1/3 the thickness of earth-grown crystals.
A new dimension in space experimentation
Based on the Space Shuttle's ability to place the Long Duration Exposure Facility (LDEF) in space and later retrieve it, a new opportunity for scientific exploration in space is studied. The LDEF which is scheduled to be placed in orbit in 1984 and returned to earth after one year in space is described. It is a large unmanned facility 9 m in length and 4 m in diameter and flying at an 482 km orbit. It is pointed out that the LDEF allows investigators to have their experiments returned to them for in-depth analysis, eliminates the need for complex systems to transmit data to earth, does not require propulsion equipment, and increases the kinds of experiments that can be performed. A description is given for each of the five categories of the experiments provided by the LDEF: (1) evaluation of the impact of space environments on materials used for thermal coatings on polymer-matrix composites, on optics, and on quartz-crystal oscillators; (2) experiments with unique heat pipe systems having the goal to achieve temperature control of + or - 6 F; (3) evaluation of solar array materials; (4) growth of single crystals of lead sulfite, calcium carbonate, and synthetic metals; and (5) scientific experiments to determine the chemistry of micrometeoroids and to identify isotopes in interstellar gas and ultra-heavy cosmic ray nuclei. Finally, the project SEEDS (Space Exposed Experiment Developed for Students) which experiments with tomato seeds behavior in zero gravity is discussed.