Multi-Platform, Multi-Architecture Runtime Verification of Autonomous Space Systems
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Autonomous systems are only capable of effective self-governing if they can reliably sense their own faults and respond to failures and uncertain environmental conditions. We propose to design a real-time, onboard runtime verification and system health management (SHM) framework called R2U2, to continuously monitor essential system components such as sensors, software, and hardware for detection and diagnosis of failures and violations of safety or performance rules during the mission of autonomous space systems, such as rovers, small satellites, or Unmanned Aerial Systems (UAS) flying in the skies of other planets. Read more about the research on NASA’s website.
This summer, the NASA sponsored Iowa Space Grant Consortium (ISGC) returned to Iowa State. The ISGC, which is part of NASA’s National Space Grant College and Fellowship Program, was founded in 1990, establishing its first headquarters at Iowa State University. Iowa State, along with Drake University, the University of Iowa, and the University of Northern Iowa make up the administrative board and academic affiliates.
Working with the Iowa Space Grant Consortium since year two is Carmen Fuchs, who serves as program coordinator. Carmen has seen the ISGC grow from a brand new program to a consortium that offers lots of opportunities for students and researchers to get involved in aerospace as well as other STEM areas.
“Wallace Sanders was the original director. He was a civil engineering professor who had a lot of contacts in the aerospace industry,” Carmen said. “He got Iowa State to write the original grant. Our main office was in Town Engineering up on the fourth floor.”
In 2010, the ISGC grant was moved to UNI until this summer when the Space Grant returned to Iowa State where it currently resides in Howe Hall. With the close proximity of the aerospace engineering department, as well as the direction of Rich Wlezien, who serves as its chair, Iowa State makes a great control center for the ISGC.
Over her 24-year career with Space Grant, Carmen has enjoyed seeing students succeed and have their work recognized. A highlight for her came when students had their experiment (Iowa Joint Experiment in Microgravity Solidification) flown on the Space Shuttle Endeavour on STS-69 and performed successfully in space.
“Students at Iowa State and Iowa build this entirely enclosed experiment and delivered it to NASA. Then NASA flew it on the shuttle and ran the experiment,” Carmen said. “So they actually got their metals melted in space on the shuttle, and had it returned.”
Carmen’s favorite aspect of working with the ISGC is watching the students grow, and seeing the impact Space Grant has on them as they start their careers.
“A lot of the alumni will write me saying having that hands-on experience with the Space Grant helped them get their jobs,” Carmen says. “It was the extra straw in their hat that other students didn’t have. Those hands-on, teambuilding experiences are really important.”
For more information about the Iowa Space Grant Consortium, please visit the newly redesigned website at www.iaspacegrant.org.
After receiving the NASA Space Technology Research Fellowship in April of 2015, aerospace engineering master’s student Kyle Webb spent 11 weeks at the NASA Langley Research Center in Hampton, Virginia. During his time at NASA, Webb fine-tuned the aerocapture guidance algorithm that he has been working on as part of his thesis work under Dr. Ping Lu.
The fellowship culminated with a simulated fly-off comparing Webb’s algorithm to algorithms that NASA had previously developed.
The goal of the simulation was to reach an elliptical final orbit around Mars while minimizing propellant consumption. The simulation tested three different vehicles using 8,000 dispersed trials each for both a one-sol and five-sol target orbit, with the main figure of merit being the delta-v requirement for which 95% of the test cases would reach the target. At the end of the simulation, Lu and Webb’s algorithm was declared the winner.
“It was great to win. Dr. Lu had flown up for the week to see the simulation so it was neat to see it actually work,” Webb said.
In addition to the simulation, Webb also sat in on the NASA wide Technical Interchange Meeting to discuss the Evolvable Mars Campaign, designed to address key issues for future human missions to Mars. The results of the fly-off were presented, and due to the algorithm’s success, it is being considered for use in a future Mars mission.
Webb had originally applied for the fellowship the previous year but was denied. His persistence paid off as he was granted the fellowship on his second try and was pleased that he didn’t give up.
“I’m happy I ended up getting it, especially after trying two times,” Webb said. “It was great to go see a NASA center for a while and see what the day to day life was like. I ended up making quite a few friends among some of the interns who were there as well.”
On this day thirteen years ago, the U.S. Space Program experienced one of its darkest days. During reentry to the Earth’s atmosphere, the Space Shuttle Columbia broke apart, killing all seven crewmembers on board. An investigation launched immediately to determine what had occurred, as well what steps could be taken to prevent further accidents. As part of the investigation, NASA brought in experts from around the world to examine the exact cause of the accident, and how to reduce the chance for reoccurrence. Bill Ellingson (B.S. ’62, M.S. ’70, Ph.D. ’74), an Iowa State Aerospace Engineering alum who was working as a senior scientist at Argonne National Laboratory was one of those experts who got the call from NASA.
Less than two minutes into the launch of Columbia’s 27th mission, STS-107, a piece of foam from the large external fuel tank broke off, striking one of the panels of the space shuttle’s left leading edge wing, causing a briefcase-sized hole. The leading edge of each of those wings were constructed from 22 individual reinforced carbon-carbon (RCC) panels that protected the wing during reentry, due to their ability to withstand extremely high temperatures. Because of the hole in the light gray RCC panel, hot gasses, with temperatures that reached up to 3,000 degrees Fahrenheit, penetrated the wing during reentry and ate away at the shuttle causing it to disintegrate.
When they were built, the reinforced carbon-carbon panels were designed to be strong enough that they could be used on the shuttle for years and years, as long as they stayed at the right temperature. If the RCC panels exceeded 3,000 degrees Fahrenheit for an extended period of time, they would start to weaken and need to be replaced sooner than planned. After each mission, technicians would see how long the RCC panels stayed at an extreme temperature to determine how much strength had been reduced. In addition, a technician would push along the bottom edge of the pieces with his or her hand, looking for soft spots. After the Columbia accident, it was clear that NASA needed a way to nondestructively assess the condition of the RCC panels in a quantitative way.
NASA needed someone who had years of experience working with different types of ceramic composites at extremely high temperatures. In addition, they needed someone who had developed noncontact and nondestructive methods to examine different types of ceramics, preferably one of the leaders in his or her field. That’s when Ellingson came in. “When NASA had this issue with Columbia, what was interesting is that they did not have people doing what I was doing, which was developing nondestructive test methods for ceramic composites,” Ellingson recalls. “So when they looked around the United States, they saw who was working with these materials, and that’s when I showed up.”
Ellingson and about 100 other scientists were split into groups to evaluate and modify different methods of nondestructive testing. The teams looked at ultrasound, Eddy current technology, shearography, and flash infrared thermal imaging. In the end, it was determined that infrared thermal imaging was the best solution. NASA called back five specialists, including Ellingson, to determine the best inspection procedure following each flight. “The five of us were tasked to come up with a procedure so that after every return from flight, NASA could do the large area flash thermal imaging, and look at the data and to assess the remaining residual strength of the wing leading edge part,” Ellingson said.
The final protocol ended up requiring a combination of three of the testing methods then comparing the results to see if a piece needed to be replaced. “We can’t afford to have false positives,” Ellingson told Argonne in 2005. “These components can cost $100,000 per part.”
In 2004, Ellingson, along with other team members, were presented with the NASA Turning Goals Into Reality Award, which celebrates the year’s most significant accomplishment that adds to the NASA legacy.
The protocol that Ellingson and his team developed was used for the final 22 missions of the space shuttle program. In July of 2011, NASA invited Ellingson along with other involved scientists to Cape Canaveral to witness the final launch of the space shuttle program.