The Kea GPS Payload is a multi-experiment GPS hardware that is designed, built and tested by ACSER,UNSW and General Dynamics NZ. It is one of the first technology demonstration for a single-board GPS receiver that can host multiple experiments.Its customisability allows it to reconfigure itself to perform one of three experiment modes below:
Mode 1: In-orbit Positioning
This is the main goal of this payload. It will exercise the standard navigation functionality of the Namuru GPS receiver when operating in low earth orbit, with the aim of validating the core receiver functionality and gaining flight heritage for the design. Results from ground-based satellite laser ranging on the spacecraft will also be performed will be used to validate the accuracy of the receiver.
Mode 2: GPS Radio occultation
The Kea GPS receiver listens to the transmissions from GPS satellites. Given their different orbits, the Earth will sometimes come between the two satellites, and its radio signal will have to pass through some of the Earth’s atmosphere before the planet blocks it out completely. The way that the signal fades in the atmosphere can be used to calculate the temperature and pressure along the line connecting the two spacecraft, providing a valuable new source of raw data for weather forecasting.
Mode 3: GPS Reflectometry
The purpose of the reflectometry experiment is to use the Kea GPS receiver to perform remote sensing using GPS reflectometry. This involves observing GPS specular reflections from the earth’s surface using a custom Left-Hand Circularly Polarised antenna array that will be installed on the nadir face of the CubeSat. Observations from oceans under different sea-state conditions, preferably at locations at which observations from other independent instruments are available can be made, are desirable. Observations from land and perhaps sea-ice can also be made. The experiment data can be used to infer sea-state, wind speed, water-land boundaries and many other unexplored applications.