Radiation Survivability of Micro-SD Cards in a Simulated Exposure to Prolonged Low Earth Orbit Space Environments

The harsh space environment can cause detrimental effects on high-density electronics such as micro-SD memory cards. High-energy electrons and ionizing radiation can induce common critical failure modes for satellites, particularly for small satellites with low shielding that often use less radiation-hardened Commercial-Off-The-Shelf (COTS) components. The objective of this research is to observe the impact of radiation on three different types of micro-SD cards in simulated Low Earth Orbit (LEO) space conditions. Radiation survivability was tested in the Space Survivability Test (SST) chamber at Utah State University that uses a ~90 mCi Sr90 source emitting broadband 0.2 to 2.5 MeV penetrating β radiation. Tests were conducted on about a dozen of micro-SD cards at a dose rate of ~2.5 Gy/hr for a period of up to ~400 hr for a cumulative Total Ionizing Dose (TID) of ~1000 Gy or ~50 times a typical annual dose (~20 Gy/yr) received for a typical CubeSat in LEO. The memory capacities of the micro-SD cards ranged from 4 GB to 32 GB with, low- and high-grade commercial multi-level cell (MLC) flash memory and industrial grade single-level cell (SLC) flash memory. Preliminary radiation tests at this facility reported memory failures occurrence at \u3c 340 Gy for the low-grade SD cards. Pre-radiation tests were performed on all micro-SD cards that included- (1) formatting with a FAT32 file system by SD Memory Card Formatter 5.0.1, (2) performing Quick Size Test (to check and report the true capacity of SD cards) and Empty Space Test (to write test files to any remaining free space on the SD cards) using FakeFlash Test 1.1.1, and (3) measuring Sequential and Random Read/Write speeds with Crystal Disk Mark software. At the end of full TID exposure, recovery tests were also performed on the damaged SD cards to check if the recovery was possible. Presentation Time: Thursday, 9-10 a.m

Simultaneous Simulation of Microgravity and Ionizing Radiation in a Laboratory Environment

A novel system was developed to simulate the combined effects of reduced gravity and ionizing radiation present during spaceflight on biological and particulate samples. The miniature rotary cell culture system (mRCCS) was designed to synchronously rotate up to five independent vessels containing particulate samples suspended in fluid media, constructed using radiation tolerant, biocompatible, and vacuum compatible materials. Reduced gravity conditions were achieved when suspended particles (e.g., 200 μm polystyrene microcarrier beads with or without adhered cell clusters) were suspended inside the vessels moving near terminal velocity in viscous neutral-buoyant fluid media with densities matched to the suspended particles to achieve neutral buoyancy. Variations in centripetal acceleration from slow rotation of the vessels limited reduced gravity environments from ~1·10-5 to ~2·10-2 g, comparable to similar commercially available systems. The effective gravitational acceleration applied to particles was calibrated through particle tracking of suspended particles within the mRCCS systems vessels. The entire mRCCS apparatus can be used in a standalone configuration for independent reduced gravity simulations or can be introduced into the Utah State University’s Space Survivability Test (SST) chamber for radiation exposure or simultaneous radiation exposure under reduced gravity. The SST chamber has a ~90 mCi 90Sr source that emits 0.2 to 2.5 MeV β radiation. The combined mRCCS and SST chamber system can provide average effective dose rates for the suspended particles, controlled over a broad range (900X) from ~3.7 mGy/day to 3.4 Gy/day by varying the source-to-sample distance and using varying slit width graphite shields. This system can provide stable, simultaneous space-like radiation and reduced gravity environments for experiments conducted on timescales of minutes to months.Initial experiments have focused on understanding cellular damage due to the effects of radiation and reduced gravity on cardio and neurological cell clusters, with a long-term goal of studying damage mitigation of biological reagents

Laboratory Simulations of Simultaneous Reduced Gravity and Ionizing Radiation Environments

A novel system has been developed to simulate the combined effects of reduced gravity and ionizing radiation present during spaceflight on biological and particulate samples. The miniature rotary cell culture system (mRCCS) was designed to synchronously rotate up to five independent vessels containing particulate samples suspended in fluid media, constructed using radiation tolerant, biocompatible, and vacuum compatible materials. Reduced gravity conditions were achieved when particles (e.g., 200 µm polystyrene microcarrier beads with or without adhered cell clusters) were suspended inside the vessels moving near terminal velocity in viscous fluid media with densities matched to the suspended particles to achieve neutral buoyancy and minimal effective gravity. Variations in centripetal acceleration from slow rotation of the vessels limited reduced gravity environments from ~2·10-2 to \u3c 1·10-5 g, comparable to similar commercially available systems. The effective gravitational acceleration experienced by the suspended particles was calibrated by tracking of particles within the mRCCS systems vessels. The entire mRCCS apparatus can be used in a standalone configuration for independent reduced gravity simulations or can be introduced into the Utah State University\u27s Space Survivability Test (SST) chamber for radiation exposure or simultaneous radiation exposure under reduced gravity. The SST chamber has a ~90 mCi 90Sr source that emits 0.2 to 2.5 MeV β radiation. The combined mRCCS and SST chamber system can provide average effective dose rates for the suspended particles, controlled over a broad range ( \u3e 900X) from ~3.7 mGy/day to 3.4 Gy/day by varying the source-to-sample distance and using varying slit width graphite shields. This system can provide stable, simultaneous space-like radiation and reduced gravity environments for experiments conducted on timescales of minutes to months

Total Ionizing Dose Tolerance of Micro-SD Cards for Small Satellite Missions

Tests have determined damage thresholds and failure rates as a function of total ionizing dose (TID) of beta radiation for various types of COTS micro-SD cards commonly used for memory storage in space applications. Radiation tolerance of high-density electronics are common critical failure modes for satellites, particularly for small satellites that often use lower shielding and less radiation-hardened COTS components. The tests evaluated SD-card formatting and read/write speeds at nine radiation intervals for up to ~ 1000 Gy TID, equivalent to ~15 times TID typically experienced annually on the unshielded exterior of satellites in Low Earth Orbit. A limited number of failures were observed beginning after ~ 400 Gy TID. Cards experiencing failures were subsequently tested at more rapid interval intervals, and typically recovered their initial read/write speeds after ≤ 24 hrs, except in more severe cases after \u3e 400 Gy TID. These results will facilitate satellite designers’ selection of the appropriate quality and cost of the micro-SD cards for their particular mission, based on reliability and radiation tolerance