OSTM/Jason-2
OSTM/Jason-2 Instruments
Poseidon-3 dual frequency altimeter
The Poseidon-3 radar altimeter is the main instrument on the Jason-2 mission. Derived from the Poseidon-1 altimeter on TOPEX/Poseidon and the Poseidon-2 on Jason-1, it measures sea level, wave heights and wind speed.
The Poseidon-3 radar altimeter is the main instrument on the Jason-2 mission. Derived from the Poseidon-1 altimeter on TOPEX/Poseidon and the Poseidon-2 on Jason-1, it measures sea level, wave heights and wind speed.
The Poseidon-3 altimeter emits pulses at two frequencies 13.6 and 5.3 GHz to measure the distance from the satellite to the surface (range). Free electrons in the atmosphere can delay the signal's return, affecting the measurement accuracy. The delay is directly related to the radar frequency, so the difference between the two measurements can be used to determine atmospheric electron content. Poseidon-3 is coupled with Doris/Diode, to improve measurements over coastal areas, inland waters and ice.
Advanced Microwave Radiometer (AMR)
The Advanced Microwave Radiometer (AMR), is an enhanced version of the Jason-1 Microwave Radiometer (JMR). Like the JMR, it acquires measurements via three separate frequency channels (23.8, 18.7 and 34 GHz) to determine the path delay of the altimeter's radar caused by atmospheric water vapor. Measurements acquired at each frequency are combined to determine atmospheric water vapor and liquid water content. Once the water content is known, the correction to be applied for radar signal path delays can be determined.
The Advanced Microwave Radiometer (AMR), is an enhanced version of the Jason-1 Microwave Radiometer (JMR). Like the JMR, it acquires measurements via three separate frequency channels (23.8, 18.7 and 34 GHz) to determine the path delay of the altimeter's radar caused by atmospheric water vapor. Measurements acquired at each frequency are combined to determine atmospheric water vapor and liquid water content. Once the water content is known, the correction to be applied for radar signal path delays can be determined.
DORIS
The DORIS instrument onboard Jason-2 will provide real-time location and precise orbit determination. DORIS measurements are also used for geophysical studies.
The DORIS instrument onboard Jason-2 provides real-time location and precise orbit determination. DORIS measurements are also used for geophysical studies, in particular through the International DORIS Service (IDS). DORIS is a dual-frequency instrument able to determine atmospheric electron content. This function complements the dual-frequency altimeter function.
Additional information on the DORIS instrument is available on the AVISO site.
Global Positioning System Payload (GPSP)
The GPSP is a tracking system that receives dual-frequency navigation signals continuously and simultaneously from 16 GPS satellites to determine the exact position of a transmitter.
The GPS Payload (GPSP) on OSTM/Jason-2 is a tracking system that receives dual-frequency navigation signals continuously and simultaneously from 16 GPS satellites to determine the exact position of a transmitter. The GPSP supports precise orbit determination by the DORIS system. It also helps to improve gravity field models and provides data for satellite positioning accurate to about 50 meters and 50 nanoseconds.
Laser Retroreflector Array (LRA)
The LRA is an array of mirrors that provide a target for laser tracking measurements from the ground. By analyzing the round-trip time of the laser beam, we can locate where the satellite is on its orbit.
The LRA is an array of mirrors that provide a target for laser tracking measurements from the ground. By analyzing the round-trip time of the laser beam, we can locate where the satellite is on its orbit. It is a completely passive reflector designed to reflect laser pulses back to their point of origin on Earth. It is used for the calibration of the Precise Orbit Determination system on the spacecraft.