The Halogen Occultation Experiment (HALOE) conducted satellite solar occultation measurements for 14 years ending on 21 November 2005. HALOE contained a calibration wheel, which included three neutral density filters that were used to examine response linearity through a combination of ground and on-orbit measurements. Although measurement uncertainties preclude a confident assessment of the true extent of nonlinearity, the on-orbit data lead to the conclusion that any existing response nonlinearity has changed by less than 2% over the mission lifetime. This conclusion eliminates a potentially significant uncertainty when using HALOE data for studies of long-term atmospheric trends.
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http://dx.doi.org/10.1364/ao.46.007811 | DOI Listing |
To enhance the dynamic performance and stability of spacecraft attitude measurement, a commonly adopted approach is to integrate a star sensor with an inertial gyroscope. While an integrated sensor system offers benefits in high-precision and high-dynamic scenarios, it also introduces errors in the extrinsic parameters of the camera and gyroscope, directly contributing to increased fixed error in attitude determination. Hence, real-time correction of integrated system parameters becomes crucial for enhancing the accuracy of attitude estimation.
View Article and Find Full Text PDFJ Astronaut Sci
July 2024
Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA.
This paper documents the results from the highly successful Lunar flashlight Optical Navigation Experiment with a Star tracker (LONEStar). Launched in December 2022, Lunar Flashlight (LF) was a NASA-funded technology demonstration mission. After a propulsion system anomaly prevented capture in lunar orbit, LF was ejected from the Earth-Moon system and into heliocentric space.
View Article and Find Full Text PDFSensors (Basel)
June 2024
Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610042, China.
Aiming to address the chicken-and-egg problem in star identification and the intrinsic parameter determination processes of on-orbit star sensors, this study proposes an on-orbit self-calibration method for star sensors that does not depend on star identification. First, the self-calibration equations of a star sensor are derived based on the invariance of the interstar angle of a star pair between image frames, without any requirements for the true value of the interstar angle of the star pair. Then, a constant constraint of the optical path from the star spot to the center of the star sensor optical system is defined to reduce the biased estimation in self-calibration.
View Article and Find Full Text PDFSci Rep
April 2024
Institute for Textile and Fiber Technologies, University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany.
Climate change necessitates exploring innovative geoengineering solutions to mitigate its effects-one such solution is deploying planetary sunshade satellites at Sun-Earth Lagrange point 1 to regulate solar radiation on Earth directly. However, such long-span space structures present unique technical challenges, particularly structural scalability, on-orbit manufacturing, and in-situ resource utilization. This paper proposes a structural concept for the sunshade's foil support system and derives from that a component-level modular system for long-span fiber composite lightweight trusses using coreless filament winding.
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