In Orbit Performance of a Fully Autonomous Star Tracker

John Leif Jørgensen

In Orbit Performance of a Fully Autonomous Star Tracker

Research output: Chapter in Book/Report/Conference proceeding › Article in proceedings › Research › peer-review

Abstract

The Department of Automation at DTU has developed the Advanced Stellar Compass (ASC), a fully autonomous star tracker, for use as high precision attitude reference onboard spacecrafts. The ASC is composed of a CCD-based camera and a powerful microprocessor containing star catalogue, image-analysis software and a search engine. The unit autonomously performs all tasks necessary to calculate the inertial attitude from a star image. To allow for flexible attitude manoeuvres, the ASC can, simultaneously, drive from one to four cameras, efficiently removing dropouts from, e.g., sun blinding of one camera. The key features of the ASC are fast and extremely robust arcsecond accuracy in a miniature design. Due to the attractive ratios of performance to mass, power and cost, the ASC has been selected as the baseline attitude sensor for a suite of missions by the major space agencies of the world. Generally, it is difficult to test and verify the true robustness and accuracy of a star tracker on ground. This is caused by the fact that only real-sky tests offer high fidelity stimulation of the sensor, while the atmosphere instabilities result in a dominant noise source intrinsically limiting the achievable accuracy. This paper compares in-orbit performance with ground test starting with a brief summary of the ASC configurations on the missions referenced, i.e. Teamsat, ASTRID2 and Oersted. Then the in-orbit operation and performance of the ASC with special emphasis on robustness and closed loop operation aspects is discussed based on specific attitude manoeuvres. This is followed by a comparison between ground-test and in orbit operation in situations where the instrument for some reason has to operate close to bright objects. For reference, simulations and in-orbit performance of stray light baffles are given. Finally, the accuracy over the lifetime is discussed. The importance of the last topic is augmented by factors such as radiation, aging by direct sun exposure and non-stellar objects.

Original language	English
Title of host publication	ESA 4th Symposion on Spacecraft Guidance Navigation and Control
Publisher	ESTEC, European Space Agency
Publication date	1999
Publication status	Published - 1999
Event	4th ESA International Conference on Spacecraft Guidance, Navigation and Control - Noordwijk, Netherlands Duration: 18 Oct 1999 → 21 Oct 1999

Conference

Conference	4th ESA International Conference on Spacecraft Guidance, Navigation and Control
Country	Netherlands
City	Noordwijk
Period	18/10/1999 → 21/10/1999

Cite this

Jørgensen, J. L. (1999). In Orbit Performance of a Fully Autonomous Star Tracker. In ESA 4th Symposion on Spacecraft Guidance Navigation and Control ESTEC, European Space Agency.

@inproceedings{336f42510383495b802fafc8f472c858,

title = "In Orbit Performance of a Fully Autonomous Star Tracker",

abstract = "The Department of Automation at DTU has developed the Advanced Stellar Compass (ASC), a fully autonomous star tracker, for use as high precision attitude reference onboard spacecrafts. The ASC is composed of a CCD-based camera and a powerful microprocessor containing star catalogue, image-analysis software and a search engine. The unit autonomously performs all tasks necessary to calculate the inertial attitude from a star image. To allow for flexible attitude manoeuvres, the ASC can, simultaneously, drive from one to four cameras, efficiently removing dropouts from, e.g., sun blinding of one camera. The key features of the ASC are fast and extremely robust arcsecond accuracy in a miniature design. Due to the attractive ratios of performance to mass, power and cost, the ASC has been selected as the baseline attitude sensor for a suite of missions by the major space agencies of the world. Generally, it is difficult to test and verify the true robustness and accuracy of a star tracker on ground. This is caused by the fact that only real-sky tests offer high fidelity stimulation of the sensor, while the atmosphere instabilities result in a dominant noise source intrinsically limiting the achievable accuracy. This paper compares in-orbit performance with ground test starting with a brief summary of the ASC configurations on the missions referenced, i.e. Teamsat, ASTRID2 and Oersted. Then the in-orbit operation and performance of the ASC with special emphasis on robustness and closed loop operation aspects is discussed based on specific attitude manoeuvres. This is followed by a comparison between ground-test and in orbit operation in situations where the instrument for some reason has to operate close to bright objects. For reference, simulations and in-orbit performance of stray light baffles are given. Finally, the accuracy over the lifetime is discussed. The importance of the last topic is augmented by factors such as radiation, aging by direct sun exposure and non-stellar objects.",

author = "J{\o}rgensen, {John Leif}",

year = "1999",

language = "English",

booktitle = "ESA 4th Symposion on Spacecraft Guidance Navigation and Control",

publisher = "ESTEC, European Space Agency",

note = "4th ESA International Conference on Spacecraft Guidance, Navigation and Control ; Conference date: 18-10-1999 Through 21-10-1999",

}

TY - GEN

T1 - In Orbit Performance of a Fully Autonomous Star Tracker

AU - Jørgensen, John Leif

PY - 1999

Y1 - 1999

N2 - The Department of Automation at DTU has developed the Advanced Stellar Compass (ASC), a fully autonomous star tracker, for use as high precision attitude reference onboard spacecrafts. The ASC is composed of a CCD-based camera and a powerful microprocessor containing star catalogue, image-analysis software and a search engine. The unit autonomously performs all tasks necessary to calculate the inertial attitude from a star image. To allow for flexible attitude manoeuvres, the ASC can, simultaneously, drive from one to four cameras, efficiently removing dropouts from, e.g., sun blinding of one camera. The key features of the ASC are fast and extremely robust arcsecond accuracy in a miniature design. Due to the attractive ratios of performance to mass, power and cost, the ASC has been selected as the baseline attitude sensor for a suite of missions by the major space agencies of the world. Generally, it is difficult to test and verify the true robustness and accuracy of a star tracker on ground. This is caused by the fact that only real-sky tests offer high fidelity stimulation of the sensor, while the atmosphere instabilities result in a dominant noise source intrinsically limiting the achievable accuracy. This paper compares in-orbit performance with ground test starting with a brief summary of the ASC configurations on the missions referenced, i.e. Teamsat, ASTRID2 and Oersted. Then the in-orbit operation and performance of the ASC with special emphasis on robustness and closed loop operation aspects is discussed based on specific attitude manoeuvres. This is followed by a comparison between ground-test and in orbit operation in situations where the instrument for some reason has to operate close to bright objects. For reference, simulations and in-orbit performance of stray light baffles are given. Finally, the accuracy over the lifetime is discussed. The importance of the last topic is augmented by factors such as radiation, aging by direct sun exposure and non-stellar objects.

AB - The Department of Automation at DTU has developed the Advanced Stellar Compass (ASC), a fully autonomous star tracker, for use as high precision attitude reference onboard spacecrafts. The ASC is composed of a CCD-based camera and a powerful microprocessor containing star catalogue, image-analysis software and a search engine. The unit autonomously performs all tasks necessary to calculate the inertial attitude from a star image. To allow for flexible attitude manoeuvres, the ASC can, simultaneously, drive from one to four cameras, efficiently removing dropouts from, e.g., sun blinding of one camera. The key features of the ASC are fast and extremely robust arcsecond accuracy in a miniature design. Due to the attractive ratios of performance to mass, power and cost, the ASC has been selected as the baseline attitude sensor for a suite of missions by the major space agencies of the world. Generally, it is difficult to test and verify the true robustness and accuracy of a star tracker on ground. This is caused by the fact that only real-sky tests offer high fidelity stimulation of the sensor, while the atmosphere instabilities result in a dominant noise source intrinsically limiting the achievable accuracy. This paper compares in-orbit performance with ground test starting with a brief summary of the ASC configurations on the missions referenced, i.e. Teamsat, ASTRID2 and Oersted. Then the in-orbit operation and performance of the ASC with special emphasis on robustness and closed loop operation aspects is discussed based on specific attitude manoeuvres. This is followed by a comparison between ground-test and in orbit operation in situations where the instrument for some reason has to operate close to bright objects. For reference, simulations and in-orbit performance of stray light baffles are given. Finally, the accuracy over the lifetime is discussed. The importance of the last topic is augmented by factors such as radiation, aging by direct sun exposure and non-stellar objects.

M3 - Article in proceedings

BT - ESA 4th Symposion on Spacecraft Guidance Navigation and Control

PB - ESTEC, European Space Agency

T2 - 4th ESA International Conference on Spacecraft Guidance, Navigation and Control

Y2 - 18 October 1999 through 21 October 1999

ER -