Space Test Program-H2-Radar Fence Transponder (STP-H2-RAFT) - 12.03.13
Science Objectives for Everyone
The RAFT mission is a student experiment from the United Sates Naval Academy that uses picosatellites to test the Space Surveillance Radar Fence and experimental communications transponders.
Science Results for Everyone
United States Department of Defense Space Test Program, Johnson Space Center, Houston, TX, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Department of Defense (DoD) - RetiredResearch Benefits
Information PendingISS Expedition Duration
September 2006 - April 2007Expeditions Assigned
14Previous ISS Missions
RAFT is a new investigation, it has not been performed in microgravity before.
- Radar Fence Transponder (RAFT) is a student experiment from the United States Naval Academy that will determine the limits of the Space Surveillance Radar Fence in detecting small satellites and test experimental communications transponders.
- RAFT will use two small cube-shaped picosatellites (5 in on a side), to transmit and receive signals from the radar fence for calibration.
- RAFT is part of the Space Test Program-H2 (STP-H2) complement that also includes MEPSI and ANDE.
The mission of RAFT is to provide the Navy Space Surveillance System, or NSSS, radar fence with a means to determine the bounds of a constellation of picosatellites otherwise undetectable to the radar fence, and to enable NSSS to independently calibrate their transmit and receive beams using signals from RAFT. This must be accomplished with two picosatellites (RAFT1 and MARScom), one that will actively transmit and receive, and one with a passively augmented radar cross-section. Additionally, RAFT will provide experimental communications transponders for the Amateur Satellite Service, the Navy Military Affiliate Radio System, and the Naval Academy's Yard Patrol Craft.
RAFT was deployed from the Space Shuttle Discovery during STS-116/12A.1 mission on December 20, 2006.
RAFT will lead to a better system of tracking an increasing population of picosatellites.Earth Applications
RAFT is a student project at the US Naval Academy Aerospace. This experiment provides students the hands-on opportunity to design and build picosatellites. By using mathematics, engineering and scientific concepts, it will prepare the next generation for careers in the Aerospace industry.
The RAFT picosatellites are ejected from the SSPL5510 cargo element, a reusable launcher. The launcher is located in the STP-H2 complement, along with the ANDE and MEPSI experiments, which is in the Space Shuttle cargo bay. The launcher will hold 2 picosatellites, RAFT1 and MARScom, which are 5 x 5 x 5 inch cubes that weigh a combined 7 kg. The crew will use a switch from inside the crew cabin to launch RAFT. Each picosatellite contains 3 antennas that will deploy once launched that will allow RAFT1 to communicate with the NSSS and MARScom to communicate with the Amateur Satellite Service, the Navy Military Affiliate Radio System, and the Naval Academy's Yard Patrol Craft.Operational Protocols
The Space Shuttle crew will initiate the launch from inside the crew cabin. The SSPL5510 launcher will release the 2 picosatellites, RAFT1 and MARScom. Once the satellites are in orbit, they will power-on and deploy their 3 antennas.
RAFT was deployed on December 20, 2006 and de-orbited on May 30, 2007 after 5 months in space. The deployment resulted in an applied torque to the satellites (see image sequence below). Several subsystems on the satellite (solar panel and thermal performance) were monitored. Volunteer ground stations were used to track the satellites. (Evans et al. 2009)
Bruninga RE, Smith B, Boden D.PCsat Success! and follow-on payloads.16th Annual AIAA/USU Conference on Small Satellites, Logan, Utah; 2002
Ground Based Results Publications
The image above shows the relation of size between nine picosatellites (also known as Cubesats) to a bottle of water. The RAFT experiment will use two picosatellites. Image courtesy of NASA, Johnson Space Center.
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The sequence of images shows the two RAFT satellite cubes being deployed from the Space Shuttle (STS-116). The bottom photo shows the onset of tumbling of the satellites. Image courtesy of DOD.
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