3 Corner Satellite


3 Corner Satellite
3CS satellites at testing facility.jpg
Two 3CS satellites undergoing testing
Country of originUnited States
OperatorCU-Boulder, ASU, NMSU, AFRL, STP
ApplicationsTechnology demonstration
RegimeLow Earth (planned)
Design life2-4 months[1]
Maiden launchRalphie/Sparkie
December 21, 2004
Failed to orbit

Three Corner Satellite (or 3CS, or 3CornerSat) consisted of three student-built microsatellites flying in formation. Primary mission objectives were to demonstrate formation flying, provide stereoscopic imaging of cloud formations, and demonstrate distributed and autonomous operations.[2]

A pair of spacecraft, Ralphie and Sparkie, was developed by the University of Colorado at Boulder and Arizona State University as part of the Air Force Research Laboratory's University Nanosat Program.[3] A third satellite, Petey, developed by New Mexico State University was originally also part of the 3CS but was not completed in time for launch.

The 3CS stack was originally slated for launch aboard the Space Shuttle in 2003, but after the Shuttle Columbia tragedy, mission organizers switched to the first launch of the Boeing Delta IV Heavy rocket. Due to a problem with the rocket during launch, the 3CS satellites on board, Sparkie and Ralphie, failed to achieve orbit.[4] The satellites were to have been dropped off at a low 180 km × 240 km, but they entered orbit at a height of only 105 km, which led to a rapid decay.

The third 3CS satellite Petey was not aboard the 3CS launch on Delta IV Heavy (due to not being ready in time) and was later donated to the National Air and Space Museum’s Steven F. Udvar-Hazy Center.

3CS placed atop the launch vehicle.
3CS placed atop the launch vehicle

Project Mission

Primary mission objectives:[5]

  • Stereoscopic imaging of clouds and other atmospheric structures.
  • Formation flying - the satellites will operate as a network to synchronize targeting and data acquisition and to relay health and status information among the satellites in the constellation.
  • End-to-End Data Systems (EEDS) will support automated operations, react to unplanned faults and opportunities, and to optimize operations and data handling.

Secondary mission objectives:

  • Demonstrate micro propulsion, by increasing the satellites' altitude to extend mission lifetime and improve data gathering capacity.
  • Demonstrate a modular spacecraft bus design.
  • Emphasize student education by allowing students to actively participate in the program.

The spacecraft were equipped with robust execution management software (Spacecraft Command Language (SCL), Continuous Activity Scheduling Planning Execution and Replanning (CASPER) software, and Context-sensitive anomaly detection software (SELMON monitoring system)


  1. ^ NASA Jet Propulsion Laboratory. "Three Corner Satellite". Retrieved 2009-01-17.
  2. ^ Stephen Levin-Stankevich. "Commanding and Safeguarding The Three Corner Satellite Constellation". University of Colorado at Boulder. Retrieved 2011-02-18.
  3. ^ Boeing (2004-12-01). "The DemoSat payload". Spaceflight Now. Retrieved 2008-08-02.
  4. ^ Ray, Justin (2005-03-15). "Delta 4-Heavy investigation identifies rocket's problem". Archived from the original on 29 August 2008. Retrieved 2008-08-02.
  5. ^ "3CSat 1, 2, 3 (Nanosat 2)". Retrieved 2011-02-22.
  • Onboard Autonomy on the Three Corner Satellite Mission

External links

  • NASA's Three Corner Satellite Project Homepage
  • NASA.gov
  • http://spacegrant.colorado.edu/3cs/