Radiation Tolerant Computer Mission on the ISS (RTcMISS) - 02.28.18

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

ISS Science for Everyone

Science Objectives for Everyone
Radiation can harm computers by energizing their circuits, erasing data and causing glitches that can affect a spacecraft’s ability to work properly. Single event effects, which result from highly energized charged particles traveling through space, cause most space-based computer failures. The Radiation Tolerant Computer Mission on the ISS (RTcMISS) tests a new computer system designed to withstand the harmful effects of space radiation, proving it works in the real space environment.
Science Results for Everyone
Information Pending

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


Principal Investigator(s)
Brock LaMeres, Ph.D., Montana State University, Bozeman, MT, United States

Larry Springer, M.S., Montana State University, Bozeman, MT, United States

Information Pending

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
National Laboratory (NL)

Research Benefits
Earth Benefits, Scientific Discovery, Space Exploration

ISS Expedition Duration
September 2016 - April 2017

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • Computers operating in space must withstand a harsh radiation environment that can cause system failures.
  • The primary failure mechanism in modern integrated circuits is due to high energy, ionizing radiation. These failures are known as single event effects (SEE). Single event effects are difficult to reproduce on the surface of the earth due to the protective nature of the atmosphere and magnetosphere, thus an International Space Station (ISS) demonstration is an ideal platform for this demonstration.
  • Single event effects are relatively infrequent (1-2 per day) in low earth orbit, so a long term mission (6 months) is needed to collect meaningful reliability information on a technology.
  • Radiation Tolerant Computer Mission on the ISS (RTcMISS) tests a new computer system that can provide improved reliability in the presence of ionizing radiation is being tested in this experiment.
  • The new computer system uses an architectural approach to fault mitigation that can be implemented on commercial-off-the-shelf parts. This significantly reduces the cost of space computing hardware.


Radiation Tolerant Computer Mission on the ISS (RTcMISS) tests new computer technology on the ISS to help improve the state-of-the-art space computing system. Using a commercial Field Programmable Gate Array (FPGA) fabricated in a process node of 45nm yields an acceptable level of total ionizing dose (TID) immunity inherently through minimal feature sizes. The use of a modern commercial FPGA also provides a significant increase in computational performance and power efficiency compared to custom, radiation hardened processors that use radiation hardened by design (RHBD) or radiation hardened by process (RHBP) techniques. The use of a commercial FPGA produces a tremendous reduction in cost by avoiding using low-volume, custom, radiation-hardened parts.
This novel single-event-effects mitigation architecture improves reliability beyond the existing SEE fault mitigation deployed on FPGA (i.e., triple modular redundancy (TMR) + memory configuration scrubbing) in order to deliver a platform that addresses all of NASA’s priorities for next generation space computers. The SEE fault mitigation approach in this project extends TMR+Scrubbing by including spare circuitry to enhance the operation of TMR and a spatially aware approach to improve traditional scrubbing. The approach to providing reliability involves breaking a commercial FPGA fabric into redundant tiles, each with the characteristics that they can fully contain the circuit of interest and also be individually reprogrammed using partial reconfiguration. Each tile contains a Xilinx MicroBlaze soft processor (32-bit RISC architecture provided by Xilinx).
At any given time, three of the tiles run in TMR with the rest of the tiles reserved as spares. The TMR voter is able to detect faults in the active triad by voting on the tile outputs. A configuration memory scrubber continually runs in the background and is able to detect faults in the configuration memory of both the active and inactive tiles. In the event of a fault in the active triad, (either detected by the TMR voter or scrubber), the damaged tile is replaced with a known good spare and foreground TMR operation continues. The damaged tile is repaired in the background by reinitializing its configuration memory through partial reconfiguration. This approach mitigates SEUs in the FPGA circuit fabric in addition to SEFIs in the configuration memory. The advantage of this approach is that foreground operation can continue while the faulted tile is repaired and reintroduced into the system in the background. Since bringing on a spare tile takes significantly less time than performing background repair via partial reconfiguration of the damaged tile, the system availability is increased. This approach has been implemented on a Virtex-6 LX75-1 FPGA with 9 MicroBlaze soft processors.

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Space Applications
All spacecraft and satellites have some degree of computer controls, which process data, command the spacecraft, and perform a wide range of tasks. Improving computers’ reliability benefits any space-based technology. The RTcMISS system is capable of improved on-board processing, which streamlines data for imaging and remote sensing missions, benefiting civilians and the military.

Earth Applications
Advances in computers designed for space also benefit users on Earth, where computers are an integral part of everyday life. Technology developed in this investigation can be used in high-risk, high-radiation environments on Earth, such as nuclear power plants, hospitals and other settings. In addition, the reconfigurable nature of the RTcMISS computer benefits computational science and large data set analysis.

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Operational Requirements and Protocols

  • This experiment is performed using the NanoRacks internal CubeLab experiment module. The experiment is delivered in the 1U CubeLab format. Once plugged into the CubeLab Frame, no further crew interaction is needed.
  • A 6-month deployment on the ISS is requested so that the computer technology can be exposed to a statistically significant amount of high energy radiation. It is anticipated that the computer will experience 2-3 radiation strikes per day, so a 6-month mission allows the computer to be exposed to >500 strikes.
  • It is requested that the experiment hardware be returned so that it can examined for radiation damage to the materials.
  • The crew install the experiment hardware in the NanoRacks CubeLab Express Locker in the Japanese Experiment Module.
  • Once installed, no further crew interaction is required.
  • Data are retrieved by NanoRacks using the NanoRacks communication system through the Stella communication system. Results data are provided to Montana State University weekly by NanoRacks.
  • In the event of a hardware failure, NanoRacks has the ability to power up the system in the CubeLab Frame without crew interaction.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites
LaMeres' Research Overview

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image Isometric View of Experiment Hardware in 1U Cube Form Factor. Image courtesy of Montana State University.
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image View of Experiment Electronics without Outer Chassis. Image courtesy of Montana State University.
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image Photo of Experiment Hardware with Chassis off. Image courtesy of Montana State University.
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image Photo of Experiment Hardware Assembled. Image courtesy of Montana State University.
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