CYGNSS Satellites
The eight CYGNSS micro-satellites can pass over the ocean more frequently than one large satellite could. This allows the satellites to capture a detailed view of the ocean’s surface.
The satellites are capable of measuring four simultaneous reflections, resulting in 32 wind measurements per second across the globe.
The observatory satellites are able to capture data from the inner core of tropical cyclones because the satellite signals can travel through extreme rainfall.
The number of satellites, their orbit altitudes and inclinations, and the alignment of the antennas are all optimized to provide unprecedented high temporal-resolution wind field imagery of tropical cyclone (TC) genesis, intensification and decay.
Key Characteristics
Each CYGNSS Observatory includes a Delay Doppler Mapping Instrument consisting of a multi-channel GPS receiver, low gain zenith antennas and high gain nadir antenna.
Attitude is 3-axis stabilized with 2.1° (3σ) knowledge and 2.8° (3σ) control using horizon sensors, a magnetometer, pitch momentum wheel, and torque rods.
Observatory mass and power are estimated to be ~25 kg and ~38 watts.
Microsatellites
CYGNSS uses a constellation of eight microsatellites to act as observatories, each carrying a Delay Doppler Mapping Instrument (DDMI). The observatories will use under 50 watts of power, less than a typical light bulb, and weigh less than 20 kg. In orbit, they deploy solar panels to reach the size of a full grown swan.
A benefit of using a constellation of microsatellites is that they will pass over the ocean more frequently than a single satellite would, resulting in a more detailed view of the ocean’s surface.
Delay Doppler Mapping Instrument (DDMI)
The DDMI will use a GPS receiver and antennas to provide unprecedented high-temporal-resolution wind field imagery of tropical cyclone genesis, intensification and decay.
DDMI Contents
- Delay Mapping Receiver (DMR) electronics unit: GPS receiver
- Two nadir-pointing antennas for collecting GNSS signals
- One zenith-pointing antenna providing space-geolocation capability
Technical Implementations of GPS Receiver
The GPS receiver performs standard GPS navigation and timing functions, and provides digital signal processing. The processing generates maps of GPS signals scattered from the ocean surface. The maps are called Delay Doppler Maps (DDMs), and the DDMI is capable of capturing four DDMs simultaneously.
Flight Segment Integration
The deployment module carries the eight observatories in two cylindrical tiers, with four observatories per tier. Once in orbit, the observatories are deployed in opposite pairs to balance forces. The deployments are spaced about a minute apart to avoid collision. If there is any deployment tipoff, the observatories will autonomously recover and orient themselves into proper configuration.
Sierra Nevada Corporation will provide the deployment module