Orion Payload Development
The Payload has two distinct elements: the GPS receivers and the Science Computer
There are 3 GPS receiver cards which all share a common interface board.
These communicate on a Token Bus with each other and with the Science Computer.
The GPS receivers perform basic absolute navigation.
The Science Computer will:
Perform precise relative state estimation and attitude estimation, using the data collected by the GPS receivers.
Store the data to be down-linked and post-processed.
Command the Orion attitude.
Operate the Orion-Emerald formation, including formation planning and coordination.
The GPS receivers are modified Mitel/Plessey Orion receiver designs. They are based on the GP2015 RF front end, GP2021 12-channel correlator, and ARM60 embedded processor. The primary hardware enhancement is the addition of a second RF front end and external clock signal. Extensive software modifications have also been made to allow functionality in this application.
The GPS receiver development is nearly complete. The basic functionality has been put in place and tested both in terrestrial applications as well as using the NASA Goddard Space Flight Center Formation Flying Test Bed.
The Science Computer is a nano-Engine by Brightstar Engineering. It is based on the StrongARM 1110 processor by Intel.
The Science Computer development is well under way, and on schedule. Multi-tasking capability as well as concurrent communications between the GPS receivers and C&DH have been developed and tested.
The following picture shows the current tested and verified integration state.
GPS receivers can communicate with each other and with the Science Computer
using the custom written Token Bus communication architecture.
Both devices (the receivers and the Science Computer) can also communicate with a C&DH emulation program. The interface protocol has been defined, and the C&DH software is currently being developed to allow it to take the place of the emulator.