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Space Test Program-H2-Microelectromechanical System-Based (MEMS) PICOSAT Inspector (STP-H2-MEPSI)


Overview | Description | Applications | Operations | Results | Publications | Imagery

Experiment Overview

This content was provided by James Keeney, Ph.D., and is maintained in a database by the ISS Program Science Office.

Brief Summary

This experiment will demonstrate the use of tiny (the size of a coffee cup) low-power inspection satellites that can be sent out to observe larger spacecraft. The small inspection satellites are enabled by microelectromechanical systems (MEMS), and will test the functioning of small camera systems and gyros.

Principal Investigator(s)

  • James Keeney, Ph.D., Kirtland Air Force Base, Albuquerque, NM, United States
  • Co-Investigator(s)/Collaborator(s)

    Information Pending


    United States Department of Defense Space Test Program, Johnson Space Center, Houston, TX, United States
    Aerospace Corporation, Los Angeles, CA, United States

    Sponsoring Space Agency

    National Aeronautics and Space Administration (NASA)

    Sponsoring Organization

    Department of Defense (DoD) - Retired

    ISS Expedition Duration

    September 2006 - April 2007

    Expeditions Assigned


    Previous ISS Missions

    Three MEPSI technology tests are scheduled from the Space Shuttle. The first, on STS-113 in December 2002, tested deployment.

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    Experiment Description

    Research Overview

    • MEPSI is a series of tests in the development of tiny autonomous satellites that can be used to observe larger spacecraft.

    • MEPSI will evaluate an active on board imaging capability can be used to assess spacecraft damages from man-made or environmental threats, monitor launch operations, and augment servicing operations.

    • The primary goal is to provide a rapid feedback capability for decision makers for detection and response to spacecraft anomalies.

    • MEPSI is part of the Space Test Program-H2 (STP-H2) complement that also includes ANDE and RAFT.


    The Microelectromechanical System-based (MEMS) PICOSAT Inspector (MEPSI) experiment series intends to demonstrate the concept of an on-board intelligent hardware agent, "InfoBot", that can be used to assist satellite operations. It is designed to enhance satellite command and control (C2) operations by providing active on-board imaging capability to assess spacecraft damage from man-made or environmental threats, monitor satellite early orbit testing (EOT) operations and augment servicing operations. MEPSI has been developed through a series of four pre-flight missions, each of increasing complexity and each improving overall satellite performance over the previous version. In December 2002, the MEPSI completed its third development mission with a successful launch from the Shuttle Endeavor (first shuttle mission). Improvements from the 2002 version are being made for this next developmental step.

    MEPSI was deployed from the Space Shuttle Discovery during the STS-116/12A.1 mission on December 20, 2006.

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    Space Applications

    MEPSI technology will lead to an image inspection capability for a low-cost survey of spacecraft while on orbit.

    Earth Applications

    MEPSI uses miniature imaging technology. This experiment may lead to new advancements in miniature imagining and relay technology which can be used in a variety of settings from medicine to public safety.

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    Operational Requirements

    MEPSI consists of 2 tethered Picosatellites that are 4x4x5 inch cube-shaped satellites. The combined mass of the two Picosats is 3.5 kg. Each satellite contains 6 cameras that are used for imaging the host vehicle. One satellite will be equipped with a small propulsion system that will allow one satellite to fly around the other satellite, transmitting images back to the ground. The satellites are contained in a MEPSI launcher which is part of the STP-H2 complement along with experiments ANDE and RAFT. The satellites will send data for analysis to a dedicated ground station.

    Operational Protocols

    MEPSI will be contained in the STP-H2 complement located in the cargo bay of the Space Shuttle. After the Space Shuttle completes it mission to the International Space Station and separates from the ISS, the Shuttle orients to the proper attitude for ejection and the Picosats will be launched from the MEPSI launcher into orbit. The satellites are connected to each other by a 50 foot tether. When the satellites are on orbit will perform a series of test to validate the MEMS devices, systems and operational concepts.

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    Results/More Information

    Information Pending

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    Related Websites

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    image NASA Image: STS11337012 - MEPSI deployed outside the Space Shuttle Endeavor on flight STS-113.
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    image This image of the Space Shuttle Discovery was taken by cameras located in MEPSI. This was taken shortly after deployment on December 20, 2006.
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    image This image shows the tail section and engines of the Space Shuttle Discovery. This image was taken by camera located in the MEPSI on December 20, 2006.
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    Information provided by the investigation team to the ISS Program Scientist's Office.
    If updates are needed to the summary please contact JSC-ISS-Program-Science-Group. For other general questions regarding space station research and technology, please feel free to call our help line at 281-244-6187 or e-mail at JSC-ISS-Payloads-Helpline.