Space Test Program-H5-integrated Miniature Electro-Static Analyzer-Reflight (STP-H5 iMESA-R) - 06.20.18

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Science Objectives for Everyone
The Space Test Program-H5-integrated Miniaturized Electrostatic Analyzer-Reflight (STP-H5 iMESA-R) is a space weather constellation, consisting of four inexpensive space weather instruments. The STP-H5 iMESA-R sensor mission is to measure plasma densities and energies to improve the forecast of the ionosphere, along with spacecraft charging effects in low-Earth orbit (LEO). The instruments have the potential to contribute to a capability of global observing systems, and are designed both to detect Space Weather disturbances in the magnetosphere and ionosphere, and for the diagnoses of satellite anomalies. STP-H5 iMESA-R observations include:  low-energy and high-energy electrons, protons, and heavy ions; magnetic field; and electric field.
Science Results for Everyone
Information Pending

The following content was provided by Geoff McHarg, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Geoff McHarg, Ph.D., U.S. Air Force Academy, Colorado Springs, CO, United States

Information Pending

United States Department of Defense Space Test Program, Johnson Space Center, Houston, TX, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Technology Demonstration Office (TDO)

Research Benefits
Space Exploration, Earth Benefits, Scientific Discovery

ISS Expedition Duration
September 2016 - August 2018; -

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • Space Test Program-H5-integrated Miniaturized Electrostatic Analyzer-Reflight (STP-H5 iMESA-R) tests concepts in LEO for long-duration space flight. This experiment investigates the interaction of ions with the background plasma environment around the ISS.
  • iMESA-R concentrates on ionosphere and ionizing radiation. Plasma irregularities ("bubbles") in the ionosphere cause scintillation. The resulting atmospheric turbulence may cause: a) Loss of Global Positioning Satellite (GPS) lock (50% availability during severe scintillation); b) Loss of SATCOM (i.e., communication).
  • Operators need to quickly distinguish between environmentally induced and possible hostile anomalies from radiation such as ingle event upset, dose effects, deep dielectric charging. Forecasting potential harmful effects is a priority.


Each Space Test Program-H5-integrated Miniaturized Electrostatic Analyzer-Reflight (STP-H5 iMESA-R) instrument provides two measurements: low energy plasma (Electrostatic Analyzer), and Radiation (Dosimeter). The STP-H5 sensor provides a better understanding of the origin and impact of plasma irregularities surrounding and interacting with orbiting spacecraft as well as in the Earth's ionosphere. The development of such a technology demonstrates the availability of low-cost techniques for monitoring those conditions.
The iMESA-R instrument allows one small miniaturized sensor suite to perform an array of plasma monitoring tasks simultaneously. By incorporating a plasma spectrometer, one can investigate spacecraft surface charging, characterize the interaction of spacecraft and the ambient environment, and detect and map significant natural events in the ambient environment. iMESA-R sensors can detect ambient plasma in Low Earth Orbit (LEO), and all seven sensors can detect higher energy ions in the auroral oval (an oval band situated between magnetic latitudes), given an appropriate pitch angle.
The iMESA-R instrumentation can also probe perturbations in the ionosphere. The instrument, derived from the WISPERS instrument flying on FalconSAT-5, is an electrostatic analyzer capable of detecting ions over the range 0 to 1500 eV. An onboard processor and data storage system can record up to 1 Gb of data for later retrieval by the US Air Force Academy. Operational Requirements []: The STP-H5 hardware complement is installed with the SSRMS and activated via ground based commands. Instrument health, status and operational data are downlinked via standard ISS 1553 communications protocols.

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Space Applications
Understanding the space environment by novel sensing technologies is used to advance future spacecraft development. Advances in technology offer an increase in efficiency and decrease in the cost of designing future spacecraft. By providing on-orbit data for understanding how spacecraft operations affect the natural environment, iMESA-R results can be used to provide warnings of potentially hazardous operating conditions within the space environment.

Earth Applications
The spacecrafts that these technologies apply to include those supporting earth-bound communications. The improvements that STP-H5 iMESA-R intends to demonstrate creates more robust and capable satellites that are used to interface with ground systems.

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Operational Requirements and Protocols
The STP-H5 hardware complement is installed with the SSRMS and activated via ground based commands. Instrument health, status and operational data are downlinked via standard ISS 1553 communications protocols. Using the NASA TReK interface, is commanded from, and data downloaded to, the US Air Force Academy in Colorado Springs, CO. Cadets and faculty operate the ground station as part of the final year cadet capstone project.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites

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NASA Image: ISS050E052652 - Space Test Program-H5 (STP-H5). Photo taken during Expedition 50.

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