CITIZEN EXPLORER

The satellite is designed to take scientific measurements and downlink them to K-12 schools. The Citizen Explorer project consists of two science flight instruments and two handheld ground instruments. The flight instruments include a spectrophotometer (informally termed "speck") that measures ozone in the atmosphere. The ground instruments include a UV-B detector and an aerosol meter. Data collected by the students from the four instruments complement each other to provide information about ozone levels in the stratosphere.

The mission objectives are threefold:

Education: Direct downlink of science data to participating K-12 schools worldwide. Data will be received at the schools using low-cost ground stations (<$800) and students can share data over the Internet.

Science: Global total ozone observations – provide a network of UV monitoring sites and provide observations of aerosol optical depth to assist in modeling surface level UV flux.

Technology: Demonstrate spacecraft autonomy, and progressive autonomy. Demonstrate "Beacon mode" communications concept or green, red, orange signal from the spacecraft depending on its current health.

Ground System Overview

The Ground System called EEMODS (End-to-End Mission Operations & Data System) will need to operate up to three spacecraft.  Interface & Control Systems, Inc.'s SCL was chosen for the command and monitoring software.  COTS packages were integrated to support:
 
 

A custom interface to ASPEN (Automated Scheduling and Planning Environment) was designed in Java to translate planner activities into SCL commands/scripts.  A future capability will implement re-planning before a pass.  The current spacecraft state and schedule will be relayed to ASPEN and a new schedule could then be automatically generated and uplinked.

Flight System

The flight processor is an x386, 25MHz with 8MB of RAM, 1MB of ROM and 8MB solid state disk, running VxWorks.  Students are integrating the flight software.  The main components are the SCL RTE, DataIO, and the Software Bus.  The students are responsible for the data acquisition, data recording and dump facilities, as well as the flight communications interfaces uplink and downlink.

SCL was chosen as the standard command and control language for both the ground and space environment.  This allows a seamless integration at the program level.  SCL is a key component to support automation on-board and on the ground and to provide a coherent interface to the scheduler. 

Links

http://citizen-explorer.colorado.edu/