Specifications

Background
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Test-bed is made up of three main components: a DSLR camera (Digital Single Lens
Reflex) which simulate the STARS sensing device, a referenced Al platform equipped
with a fine pointing rotating device controlled via an RS232 serial interface and a target
image. The same Landsat 7 image used for numerical simulations, was printed and used
as a target for a 1 DOF platform. Preliminary results showed that the algorithm was able
to work also with real images (affected by high noise level due to printing characteristics)
with reduced performances and an accuracy of about 100 arcseconds (0.02°) on the
controlled angle was achieved [Ref (1)].
2.3 LCCES
The objective of this study was to investigate the possibility to develop a Low Cost
Coarse Earth Sensor suitable for LEO and GEO orbits and to be used either as a stand-
alone sensor or as temporary back-up for more accurate attitude sensor like star trackers.
A sensor like the LCCES will be a potential candidate for the ALMASat-EO mission
because of its capability of functioning also during eclipse; the LCCES will guarantee a
coarse attitude determination when sun sensors aren‟t functioning in order to avoid long
re-aligning maneuvers when passing from eclipse to daylight during orbiting. Thanks to
the experience acquired with the AMSC the LCCES is based on an uncooled thermal
detector, an area scan microbolometer made by ULIS, with 384 x 288 pixels (25 µm
pitch) designed for high end applications (see Table 1).
This device is not space qualified, but is compliant to the standard MIL-STD 810F
and MIL-STD 883 and it has been selected as sensing device for the MERTIS spectral
imager that will probably fly onboard the BepiColombo mission. Two preliminary optical
layouts able to maintain the Earth disc inside the optical FOV were proposed.
Parameters
Values
Pixel dimension
25 µm x 25 µm
Thermal time constant
3.8 to 9 ms
Optical fill factor
>80%
Spectral response
8-14 µm
Absorption
> 85%
Thermal coefficient
resistance
> 2.2%/K
Resistance non uniformity
< 2%
Table 1: LCCES Microbolometer specifications