Star tracker scan mode capability for the New Horizons mission

Haley, David; Strikwerda, T. E.; Ailinger, Kevin; Casini, R.; Landi, A.; Bettarini, Rossano

doi:10.1016/j.actaastro.2005.07.059

Cited by 6 publications

(5 citation statements)

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“…Unfavorable motion error will be introduced if the smeared starspot is used for in-orbit correction. To obtain a lower position error, the TDI or variable frame rate technology was employed on the star tracker (van Bezooijen et al 2002;van Bezooijen 2003;Haley et al 2006;Blarre et al 2008) s  , implementation of TDI can obtain accuracy to be virtually the same as static performance. Variable frame rate is another effective approach to keep static performance by adjusting the integration time according to the velocity vector.…”

Section: Error Resulting From Motionmentioning

confidence: 99%

“…For an in-flight star tracker, apart from device noises, we should know how these important factors, such as motion of platform, drift in focal length, range of star magnitude, and color dispersion of stars, contribute to the overall position uncertainty (Liebe 2002;van Bezooijen et al 2002;van Bezooijen 2003;Haley et al 2006 andBlarre et al 2008). In this section, the theoretical error models of these parameters are studied to derive proper i dF .…”

Section: Error Boundary Of Some Influential Error Sourcesmentioning

confidence: 99%

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Theoretic Studies of Full Constraints on a Star Tracker's Influential Error Sources for In-orbit Calibration

Zhang¹,

Hao²,

Wang³

et al. 2016

PASP

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To collect star transits data qualified for in-orbit calibration, this study derives the full error constraints to limit star trackerʼs influential error sources and computes their error boundaries from a theoretical perspective. The full constraints, including not only the minimum variance estimation of position but also the error bound prediction of scale and intensity of Gaussian-shaped starspots, are studied based on the Cramér-Rao Lower Bound (CRLB) theorem. By imposing these constraints on motion, drift in focal length, and other factors, their boundaries could be determined before launch. Therefore, the in-orbit correction accuracy is expected to be close to CRLB through suitable implementation of these constraints. The correctness of the theoretical position error of motion is demonstrated by the data-fitting procedure against test results of star tracker on dynamic performance. The simulation result shows that the drift in focal length can generate an error with the same magnitude as detector noise and thus might be the dominant error source when star tracker is working under stationary circumstance. Using the accuracy performance of some typical star trackers, this study shows that the CRLB constraint may be very effective to estimate the overall position error of a starspot or one axis, valuable data that can be used for online calibration. The overall position uncertainty analysis shows that a weighted method can be employed for calibration, a process where star data can be given a weight in inverse proportion to the CRLB value.

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Section: Error Resulting From Motionmentioning

confidence: 99%

Section: Error Boundary Of Some Influential Error Sourcesmentioning

confidence: 99%

Theoretic Studies of Full Constraints on a Star Tracker's Influential Error Sources for In-orbit Calibration

Zhang¹,

Hao²,

Wang³

et al. 2016

PASP

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“…Under favorable working conditions, where the imaging background is clean and the vehicle is steady, star acquisition can be easily achieved and the location accuracy is high. However, in advanced applications such as high-resolution observation, deep space exploration, and defense tasks, star sensor must work under complex conditions [4][5][6]. Different types of interferences, such as Gaussian noise, single point noise, and uneven illumination are inevitable during imaging.…”

Section: Introductionmentioning

confidence: 99%

Accurate and Autonomous Star Acquisition Method for Star Sensor under Complex Conditions

Zhang

Niu

et al. 2017

Mathematical Problems in Engineering

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Star sensor is a preferred attitude measurement device for its extremely high accuracy. Star acquisition is the essential and critical procedure, which is aiming at acquiring accurate star areas. However, degenerated acquisition results under complex conditions become one of the major restrictions for modern star sensor. In this paper, an accurate and autonomous star acquisition method is proposed. Mathematical morphology and variable thresholding are combined for accurate star extraction; motion PSF is estimated in frequency domain and nonlinear filter is adopted for star restoration. Accurate star acquisition can be achieved based on only one star image. Simulations and laboratory experiments are conducted for verification. Several existing methods are also reproduced for comparison. Acquisition results demonstrate that the proposed method is effective and an excellent performance can be achieved autonomously under complex conditions, along with more detected stars and improved acquisition accuracy.

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“…To keep the number of G&C sensor components to a minimum, New Horizons required a star tracker that could operate autonomously both in a standard "staring" mode and in a spin-stabilized "scanning" mode [1][2][3]. This dual-mode operation is particularly important for a low cost, low mass mission with a planned lifetime of 15-20 years, and the capability to have accurate attitude knowledge in both modes from a single sensor is especially attractive in terms of the usual trade parameters (cost, mass, power, reliability, etc.).…”

Section: Introductionmentioning

confidence: 99%