Technology Database  Geodezy & Navigation A NEW GENERATION EARTH HORIZON SENSOR
A
New Generation Earth Horizon Sensor
 An Earth Horizon Sensor (EHS) of
a new generation is being developed for spacecraft attitude determination and
autonomous navigation systems. The EHS produces digital signals proportional to
the deviation of the direction to the center of the Earth from the frame axis of
the device.
Most existing devices for this
purpose make use of mechanical scanners to obtain infrared Earth images. The
moving mechanical parts result in a short lifetime, high weight, and
considerable power consumption of the device. Besides, the moving mechanical
parts create rotational momentum, which may influence the attitude of small
satellites.
A small group of devices make use
of electronic scanning to obtain infrared Earth images. The core of such devices
is an original radiation detector, which has to be deeply cooled and thermally
stabilized. This results in a high weight and considerable power consumption.
EHS characteristics:
|
№ |
Parameter |
Value |
|
new |
existing devices |
|
1. |
Orbit |
35000 ... 40000 km |
|
2. |
Spectral range |
14 ... 16 mkm |
|
3. |
Field of view |
±14° х ±14° |
±(14-16)° х ±(14-16)° |
|
4. |
Field of measure |
±2° х ±2° |
±(0.3-1)° х ±(0.3-1)° |
|
5. |
Accuracy (З s ) |
2 arc min |
3-6 arc min |
|
6. |
Update time |
0.5 s |
0.1-1 s |
|
7. |
Overall size |
120 х 123 х
160mm |
- |
|
8. |
Weight |
1,6 kg |
3-4 kg |
|
9. |
Average power consumption |
Not more than 2
Вт |
4-7 Вт |
|
10. |
Mounting plane temperature |
-20°С...+55°С |
- |
|
11. |
Life time |
more than 12 years |
7-10 years |
The EHS is a static two-coordinate device using
an original non-cooled multipixel infrared radiation detector. All the
electronic modules have built-in redundancy.
The EHS has the following distinctive features:
- the use of ceramic materials for the case
results in long-term stability of the case and, consequently, in stability and
accuracy of the measurement results throughout the lifetime of the instrument;
- the hardware implementation of the image
centroid computation algorithm in special integrated circuits makes it
possible to do without memory chips, which are a drawback of space equipment
operating under exposure to radiation;
- the original non-cooled infrared radiation
detector dispenses with the need for a heavy and power-consuming thermal
stabilization subsystem.
The multipurpose EHS design
allows for modification for any spacecraft working in circular fixed-altitude
orbits from 300 to 45,000 km high. The EHS cost is substantially lower than that
of existing devices with equal technical parameters and will not exceed $120,000
in serial production.
Source: SciTecLibrary.ru
Publishing date: January 16, 2001
To make an inquiry on the technology you are interested in
Back
| 
