Figure 1. RapidScat DIB top-level software architecture.

The legacy SeaWinds scatterometer radar needed to be interfaced to the International Space Station (ISS) without any modifications. It had been designed to fly on the Adeos II spacecraft. An interface to translate between ISS protocols and the existing radar interface was needed both for commanding and for science data return.

The RapidScat flight software provides a payload interface to the ISS 1553 and Ethernet. It is architected with an ISS interface side to implement the ISS protocols, and a payload side that can be modified or replaced for future payloads. The payload side as implemented provides the serial and discrete interfaces to the radar, as well as power control and timekeeping.

Figure 2. Flight software context.

The software is implemented using a component-based architecture in C++, giving it strong reuse potential for future ISS missions. The protocols required by ISS are provided as an ISS payload interface. The software is currently hosted on a commercial Intel platform including a single custom board for the radar interface. Memory requirements are approximately 2 MB.

This work was done by Leonard E. Day, Timothy K. Canham, Tom Q. Huynh, Eric Nicolich, Amalaye Oyake, and Mehran Gangianpour of Caltech for NASA’s Jet Propulsion Laboratory. This software is available for license through the Jet Propulsion Laboratory, and you may request a license at: . NPO-49428