Engineering topics

Schartel, W. A.

Publications and source records attributed to Schartel, W. A..

5 records

NASA NTRS1985

Operational fitness of box truss antennas in response to dynamic slewing

A parametric study was performed to define slewing capability of large satellites along with associated system changes or subsystem weight and complexity impacts. The satellite configuration and structural arrangement from the Earth Observation Spacecraft (EOS) study was used as the baseline spacecraft. Varying slew rates, settling times, damping, maneuver frequencies, and attitude hold times provided the data required to establish applicability to a wide range of potential missions. The key elements of the study are: (1) determine the dynamic transient response of the antenna system; (2) calculate the system errors produced by the dynamic response; (3) determine if the antenna has exceeded operational requirements at completion of the slew, and if so; (4) determine when the antenna has settled to the operational requirements. The slew event is not considered complete until the antenna is within operational limits.

Bachtell, E. E.↗

NASA NTRS1985

System and structural dynamic observations of a slewed box truss antenna

A parametric analysis was performed in order to define the slewing capability of the Earth Observation Spacecraft (EOS) box-truss antenna. The input data for the analysis consisted of the slew rate, settling time, damping, maneuver frequencies, and attitude hold times of the antenna. The dynamic transient response of the antenna was evaluated, and the results are compared with NASA operational requirements. The results of the parametric analysis are summarized in a series of tables.

Bachtell, E. E.↗

NASA NTRS1984

Technology needs of advanced Earth observation spacecraft

Remote sensing missions were synthesized which could contribute significantly to the understanding of global environmental parameters. Instruments capable of sensing important land and sea parameters are combined with a large antenna designed to passively quantify surface emitted radiation at several wavelengths. A conceptual design for this large deployable antenna was developed. All subsystems required to make the antenna an autonomous spacecraft were conceptually designed. The entire package, including necessary orbit transfer propulsion, is folded to package within the Space Transportation System (STS) cargo bay. After separation, the antenna, its integral feed mast, radiometer receivers, power system, and other instruments are automatically deployed and transferred to the operational orbit. The design resulted in an antenna with a major antenna dimension of 120 meters, weighing 7650 kilograms, and operating at an altitude of 700 kilometers.

Herbert, J. J.↗

NASA NTRS1984

Mission planning for large microwave radiometers

Earth orbiting, remote sensing platforms that use microwave radiometers as sensors are susceptible to data interpretation difficulties. The capability of the large microwave radiometer (LMR) was augmented with the inclusion of auxillary sensors that expand and enhance the LMR capability. The final system configuration demonstrates a holistic approach in the design of future orbiting remote sensing platforms that use a LMR as the core instrument.

Schartel, W. A.↗

NASA NTRS1983

Earth observation system: Spacecraft design

The Earth Observation Satellite (EOS) was a study funded by NASA Langley Research Center. The study was a system investigation of the total spacecraft integration with its major subsystems and sensors. Mission optimization and ranking using various sensors was also an objective of the contract. Integrating the spacecraft and major subsystems with the large microwave radiometer was done, essentially making the radiometer a free-flyer without an external spacecraft. Another program objective was to provide design and analysis data on microwave radiometer satellites augmented with additional Earth, ocean, and atmospheric sensors. A top-down systems approach resulted in a detailed design integrating subsystems and sensors into the microwave support structure. An important objective of the program was to identify technology needs for Earth observation satellites. The definition and understanding of these design drivers are critical in order to set priorities for future EOS work.

Herbert, J. J.↗