The Attitude Determination and Control Subsystem (ADCS) is a critical
component of a satellite that is responsible for maintaining its orientation
and pointing accuracy. It achieves this by accurately determining the
satellite’s attitude (orientation in space) and then using actuators to control
its motion and maintain the desired orientation.
★Sensors for Attitude Determination and Control:
* Star Trackers:
* Provide highly accurate attitude information by tracking celestial objects.
* Sun Sensors:
Detect the direction of the Sun, providing coarse attitude information.
* Magnetometers:
Measure the Earth’s magnetic field, which can be used for attitude
determination.
Particularly useful for low-Earth orbit satellites.
Inertial Measurement Units (IMUs):
Measure the satellite’s angular rate and linear acceleration using
gyroscopes and accelerometer
Provide short-term attitude information and are crucial for rapid
maneuvers.
* Magnetorquer
also known as a magnetic torquer or torque rod, is a device used on satellites
for attitude control, detumbling, and stabilization. It consists of
electromagnetic coils that create a magnetic dipole when current is passed
through them. This dipole interacts with the Earth’s magnetic field,
generating a torque that can be used to rotate the satellite.
Function:
* Attitude Control: Magnetorquers can be used to precisely control the
orientation of a satellite by applying small torques to adjust its attitude. This
is essential for tasks like pointing antennas towards Earth or keeping solar
panels aligned with the sun.
* Detumbling: If a satellite starts to spin uncontrollably, magnetorquers can
be used to apply a braking torque to slow it down and stabilize its rotation.
* Momentum Dumping: Reaction wheels are often used for attitude control,
but they can accumulate angular momentum over time. Magnetorquers can
be used to “dump” this excess momentum by applying a torque in the
opposite direction.
★Primary Sensors for gas Detection:
* Interferometers
A type of spectrometer that uses interference patterns to measure the
spectrum of light and provide highly accurate measurement of gas
concentrations.
Hyperspectral Imagers:
Capture images in numerous narrow, contiguous spectral bands.
Ideal for mapping large areas and identifying potential methane emission
hotspots.
★Shortwave Infrared (SWIR) Spectrometers:
Sensitive to the spectral signatures of methane and other gases.
Well-suited for precise measurements of gas concentration and
distribution.
Can be used in conjunction with hyperspectral imagers for targeted
analysis of specific regions.
