Ongoing experiments at ISS as commercial electronics exceed current radiation hardening requirements
Several experiments aboard the International Space Station are testing whether the space agency can move beyond traditional rad-hard components.
If all goes according to plan, a SpaceX Dragon cargo ship returning from the International Space Station this fall will deliver back to Earth and waiting engineers a pair of servers that will have flown aboard the orbiting laboratory and testbed for nearly a year. The idea is to simulate a nearly year-long trip to Mars and determine whether off-the-shelf hardware can hack it in deep space.
Meanwhile, the space agency is readying an ARM processor core design as the foundation of its next generation of space electronics. It has also examined the effects of radiation on memory chips.
Under a NASA project called Spaceborne Computer, Hewlett Packard Enterprise engineers supplied a pair of two-socket servers installed on the space station. (An identical ground-based pair serves as a “control group” for the experiment.) The HPE servers were launched last August to assess whether NASA can eventually shift from expensive radiation-hardened components to commercial hardware that is proving increasingly resistant to the damaging effects of ionizing radiation.
Radiation hazards associated with a trip to Mars — at least 35 million miles at its closest approach to Earth — would likely be far greater than those in Earth’s orbit. Nevertheless, HPE engineers note that current commercial electronic components far exceed current radiation hardening requirements for the space station.
The two onboard servers are meant to mirror machines at NASA’s Ames Research Center that handle much of the processing required to support the space station. Mark Fernandez, an HPE engineer and co-principal investigator for the Spaceborne Computer experiment, said that one server is being run as fast as possible while the second runs slower. “If an anomaly occurs and it only occurs on the fast one, [then operators] can slow things down.”
The goal of the experiment is to determine whether the machines could survive a trip to Mars, function properly, and, if so, still provide astronauts with the right answers, explained Fernandez.
The current schedule calls for the servers to be returned to Earth in November aboard a Dragon cargo ship. HPE investigators would then conduct a failure analysis on components to determine how they “aged” after a year in space, added Fernandez.
NASA’s space-based computing initiative dates back to 2014 with SGI, a long-time supplier of computing gear to NASA Ames. SGI was acquired by HPE in 2016.
According to the mission description, power consumption and, therefore, processing speeds are being reduced when the space station is being zapped with high levels of particle or electromagnetic radiation. The intent is to find out if the servers can still operate correctly at slower speeds.
The Gen 9 Apollo 40 family Xeon-based servers are running computing- and data-intensive applications under fluctuating radiation conditions while investigators monitor power consumption and “dynamically tune the power consumed” to gauge the overall performance of the Spaceborne Computer during a simulated trip to Mars, said program officials.
NASA has long specified traditional and expensive radiation hardening of electronic components either by adding redundant circuits or using insulating substrates on semiconductor wafers. That brute force approach is expensive. HPE engineers came up with what they say is a cheaper approach for hardening electronics: “…simply slowing down a system in adverse conditions can avoid glitches and keep the computer running,” according to an HPE blog post.
The server experiment also makes use of a relatively recent commercial space capability. SpaceX — short for Space Exploration Technologies Corp. — is, so far, the only commercial entity able to not only deliver supplies to the space station but also return a cargo ship to Earth with experiments and the valuable data that they collect.
SpaceX has been flying Dragon cargo missions to the International Space Station since May 2012.
Meanwhile, key components for future space computing platforms are expected to be available in the next few years. For example, the space agency expects its next general-purpose processor, a variant of the ARM Cortex-A53, to be cleared for launch in 2020.
NASA selected the ARM processor in 2016, meaning that it had likely frozen that part of its design for a next-generation manned spacecraft. Observers note that the Cortex-A53 was introduced in 2014, meaning that by 2020, the microprocessor core would be ancient by commercial electronics standards. Nevertheless, it represents an upgrade for space electronics that have largely failed to keep pace with Moore’s Law scaling.
The ARM processor also has made a trip to the space station in 2016 as part of NASA’s Radiation Hardened Electronic Memory Experiment. The joint NASA–Air Force project examined how often SRAMs malfunction when struck by high-energy particles in space. The memory experiment was monitored by an ARM-based microcontroller.
— George Leopold is the former executive editor of EE Times and the author of Calculated Risk: The Supersonic Life and Times of Gus Grissom (Purdue University Press, 2016).