ABSTRACT The Active Segmented Mirror is a key subsystem of the Active Phasing Experiment. The size of the ASM is 154 mm in diameter. It will be used to test new types of phasing sensors recently developed within the ELT design study... more
ABSTRACT The Active Segmented Mirror is a key subsystem of the Active Phasing Experiment. The size of the ASM is 154 mm in diameter. It will be used to test new types of phasing sensors recently developed within the ELT design study supported by the European Union. To our knowledge it is the first time that such miniature active optics composed of hexagonal segments having 3 degrees of freedom with a resolution of the order of a few nanometers and a range of several micrometers is manufactured. The ASM is composed of 61 hexagonal segments called "modules". Each module is assembled, glued and integrated from standard (piezo-actuators) and custom-made (mirrors, mechanics) parts procured from industries. The ASM has been designed and integrated at the European Southern Observatory. Specifications, designs, assembly tools, hand work skills, electronics, software, control algorithms and test procedures are the field of competences required to obtain in the end a "plug and play" product. The concept of the ASM is tested and validated by a prototype version composed of 7 modules equivalent of the central area of the ASM itself. The design, integration and results of the ASM tests are presented.
Research Interests:
The Swedish small satellite Odin, launched February 20, 2001, combines two different scientific disciplines, astronomy and atmospheric research. It bas a 3-axis stabilised, zero momentum, attitude control system that operates in two... more
The Swedish small satellite Odin, launched February 20, 2001, combines two different scientific disciplines, astronomy and atmospheric research. It bas a 3-axis stabilised, zero momentum, attitude control system that operates in two different modes, an inertial pointing astronomy mode and an atmospheric mode providing pointing/scanning of the Barth limb. The absolute pointing requirements at the ACS sub-system level is 8 arcseconds in inertial pointing mode and 1 arcminute in Barth scanning mode, requirements that after the commissioning phase bas been fulfilled with margin. This article presents the basic principles and methods for the on ground Attitude Reconstruction S/W and the principles and methods for the Calibration S/W .The operational aspects are emphasised. The Calibration S/W is responsible for estimation of biases, scalefactors and alignment parameters for the prime sensors -the two medium Field Of View Startrackers and the three 2-axis DTa ayropackages. In-flight resul...
Research Interests:
The Swedish small satellite Odin, launched February 20, 2001, combines two different scientific disciplines, astronomy and atmospheric research. It has a 3-axis stabilised, zero momentum, attitude control system (ACS) with two different... more
The Swedish small satellite Odin, launched February 20, 2001, combines two different scientific disciplines, astronomy and atmospheric research. It has a 3-axis stabilised, zero momentum, attitude control system (ACS) with two different science/pointing modes, an inertial pointing astronomy mode and an atmospheric mode providing atmospheric limb scanning or constant altitude pointing. The ODIN ACS is unique - the first in its kind - to handle the two fundamentally different requirements from the Astronomy and Aeronomy missions. The flexibility built into the Attitude Control and Determination System provides high-accuracy pointing/tracking capability of celestial and solar system objects as well as pointing/tracking of Earth related and/or Earth fixed objects. The ACS actuators are reaction wheels and magnetic coils and prime sensors for attitude determination are star trackers and high performance gyros. The absolute pointing requirements on the scientific modes are 15 arc-seconds ...
Research Interests:
Research Interests:
The Swedish small satellite Odin combines two different scientific disciplines, astronomy and atmospheric research. It has a 3-axis stabilized, zero momentum, attitude control system that operates in two different modes, an inertial... more
The Swedish small satellite Odin combines two different scientific disciplines, astronomy and atmospheric research. It has a 3-axis stabilized, zero momentum, attitude control system that operates in two different modes, an inertial pointing astronomy mode and an atmospheric mode providing pointing/scanning of the Earth limb. The reference attitude for the atmospheric mode is created by a versatile reference attitude generator, providing also capability for observing and tracking any celestial or solar system objects. The absolute pointing requirements in the scientific modes are 15 arc-seconds inertial pointing and 1.2 arc-minutes in atmospheric mode reconstructed attitude. One part of the Odin mission is to observe the formation of the ozone holes at the poles in spring and fall and another is to observe moving celestial objects such as comets. The unpredictability of when such observation opportunities occur together with rapidly changing scientific demands put high requirements ...