Radiation Tolerant Memory for Curiosity Observations
The unique stacking technology for RTIMS, from top: 1) first layer of components added to the package, 2) remaining layers assembled, 3) pure epoxy resin molding, 4) nickel and gold plating, and 5) final tantalum shielding. (Credit: Jeff Herath)
In 2009, a memory array developed at the Langley Research Center was selected for use on the Chemistry & Camera (ChemCam) instrument onboard the Mars Science Laboratory (MSL) Curiosity rover. The Radiation Tolerant Intelligent Memory Stack (RTIMS), originally developed for Earth-observing missions at geostationary and low Earth orbit, features state-of-the-art chip stacking construction, radiation shielding, and radiation mitigation technologies.
On Mars, RTIMS has controlled the firing of the Curiosity’s ChemCam laser, data acquisition, data buffering, and communication with the Rover Compute Element. ChemCam uses a laser to vaporize materials up to nine meters away on the surface and analyze the elemental composition of those materials.
RTIMS has helped safeguard Curiosity observations with novel radiation shielding and radiation mitigation technologies. RTIMS incorporates shielding at the component level instead of system level, which increases reliability. A self-scrubbing and event detection system, triple redundant digital memory, and in-flight-reconfigurability further improve radiation tolerance, allowing RTIMS to overcome errors and adapt to changing mission conditions.
RTIMS also provided a significantly smaller and lighter memory array: At 42.7mm x 42.7mm x 13.0mm, RTIMS reduced the footprint by nearly 80%. By stacking individual chips, heterogeneous electronic parts – a reprogrammable FPGA, six synchronous dynamic random-access memories, a linear regulator, and the radiation mitigation circuitries – could be built into a single component.
MSL was not the only ride into space for RTIMS. Astrium, a European aerospace company, used RTIMS arrays for communications satellites, and 3D Plus Inc., a partner in the development of RTIMS, has also commercialized and sold the modules for a variety of applications.