Faculty at the McClellan Nuclear Research Center conducted neutron imaging on certain components of the NASA Perseverance rover to ensure the rover’s functioning abilities

On Feb. 18, National Aeronautics and Space Administration’s (NASA) Perseverance rover landed at the Jezero Crater on Mars after seven months of space travel. This was made possible by the contributions of the McClellan Nuclear Research Center, operated by UC Davis.

         The research center’s mission statement is to “provide educational and research opportunities for the advancement of the nuclear sciences in a safe and pro-active environment.” According to Wesley Frey, the director of the McClellan Nuclear Research Center, the center was originally constructed as a base for the U.S. Air Force. It was run by the Air Force for about 10 years before it was sold to UC Davis in 2000 and has been run by the university ever since.

         As the center’s director, Frey’s role is to find new applications for neutron imaging, a vital research technique for the aerospace industry. According to Frey, potential examples include building improved systems to observe water uptake in plant roots so that water can be conserved and still produce the same crop yield and quality. This application is more in line with UC Davis’ goal to improve the quality of agriculture.

         The McClellan Nuclear Research Institute is also known for its outreach program that brings about 1,000 high schoolers to the center every year to see the Training, Research, Isotopes, General Atomics (TRIGA) Mark ll reactor and conduct experiments. Though the program was temporarily discontinued due to the COVID-19 pandemic, Frey hopes to resume the program this fall.

The McClellan Nuclear Research Institute also played a critical role in Perseverance’s landing on Mars. The technology used can be compared to an X-ray. These work and produce images with contrast because X-rays are preferentially absorbed in higher atomic number and more dense material like bone than lower atomic number and less dense materials like fat, muscle and skin.

Neutrons interact with material a little differently and are effective at interacting with hydrogen and carbon surrounded by metals. For example, neutron radiography can be used to image flowers inside a lead container because neutrons go through lead easily and can interact with flower material, according to Frey.

This technology is used to image pyrotechnic devices such as an airbag initiator. The initiator works by having a small explosive charge that sets off a gas-generating reaction to inflate the airbag. The majority of devices received at the research institute are one-time-use devices. The images make sure the devices are assembled correctly through nondestructive testing.

The neutron imaging method works similarly to X-rays, but instead of an X-ray tube, a neutron source such as a nuclear reactor is needed. 

The rover landing on Mars required one-time-use explosives like an airbag. The engine start up and space separations are possible with energy transfer lines, a fast-burning fuse that carries a signal from one place in the vehicle to the other. The nuclear research institute captured images of these lines using their TRIGA Mark ll reactor.

The institute is distinguished as one of two facilities in the country that can do this. There are dozens of reactors in the country similar to that of UC Davis, but only two are built to do this specific type of work of capturing images using neutron radiography, according to Wesley.

The imaging technique was used for the lander equipment as well. Images were taken of the generator that pushed out the parachute and of the explosive pellet that severed the parachute cords.

The reactor also imaged the NASA standard initiator that starts rockets that are fired on the lander, more pellet cutters responsible for cutting the four cords that lower the lander down and the four propellant tanks on the lander to make sure the rubber diaphragms inside the tanks are intact. This is an efficient way to make sure that all the moving parts of the equipment are placed correctly, according to Frey.

Dawn Sumner, a professor in the UC Davis Earth and Planetary Sciences Department, is one of the scientists on the Curiosity rover team and works directly with the rover, interpreting the data it gathers on Mars. 

“It’s still going strong, collecting excellent scientific data,” Sumner said.

         The Curiosity rover and Perseverance rover missions are connected because the results from the Curiosity are being used to make improvements to Perseverance, such as having the ability to map out the distribution of different types of organic molecules more efficiently. The two rovers are also in different locations on the planet and are used to make comparisons while asking the same scientific questions.

         “Different areas have different characteristics, and we need to explore a lot of places to understand the planet,” Sumner said. 

         The Curiosity and Perseverance missions are both international collaborations and consist of individuals with a variety of approaches working together on a difficult task. Missions like these inspire the younger generations to want to improve the world through science and engineering, according to Sumner.

         “I hope the public can be inspired by what we can do as a society. If we can land on Mars, we can solve a lot of the problems on Earth,” Sumner said. “We just need the will and persistence and resources to do so.”

Written by: Francheska Torres – science@theaggie.org

Extreme cold weather conditions caused failure of power plants, leaving Texans without electricity

The devastating conditions in Texas have been broadcasted across the country as Texans have suffered through several crises due to power outages, which stemmed from a series of severe winter storms beginning Feb. 10. Residents have had to go days without adequate heat, electricity and water—some losing their lives due to a lack of these resources. Such events have caused speculations surrounding the winter storm’s potential link to climate change. Yet Matthew Igel, an adjunct professor in the department of land, air and water resources, explained that this may not necessarily be the case.

“There’s some disagreement about the role of climate change in these kinds of events,” Igel said. “Certainly these temperatures are uncommon in Texas, but they’re not unprecedented. It’s not that these kinds of events historically have been impossible, but they are very rare.”

He explained that he is hesitant to attribute this particular snowstorm to climate change, and that similar extreme weather events happened in Texas in the early 1900s and in 1985. For this snowstorm in particular, he explained that the polar vortex—cold air trapped in the arctic—became unstable due to a pattern in the atmosphere known as blocking. Igel elaborated that air began to build up over the Pacific, which led to the slowing down of the polar vortex. This created an instability that allowed the cold air from the polar vortex to migrate toward the Southern U.S. 

“It’s easy to think of cold air trapped at the arctic as like a spinning top,” Igel said. “So when a spinning top spins really fast, it’s nice and stable. It doesn’t move. But when a top starts to slow down, it can start to wobble.”

Although there is some evidence that how much the polar vortex wobbles may increase as the world grows warmer, this is still a growing field of research. Though these recent events may not necessarily shed light directly on climate change, they do highlight another area in need of change: power grids. 

When extreme cold temperatures hit Texas, the state’s power plants were unable to continue operations. According to an article by the New York Times, out of natural gas, coal, nuclear and wind power plants, natural gas production was affected the most. The article further explained that, simultaneously, demands for electricity increased past estimations, forcing the Electric Reliability Council of Texas (ERCOT) to initiate controlled power outages. 

“Electricity systems need to balance supply and demand every second or it can result in complete grid collapse that can take weeks to recover from,” said James Bushnell, an economics professor, via email. “In order to prevent the total collapse, ERCOT, the system operator in Texas, started rotating blackouts. The supply shortfall was so massive that up to half of all demand had to be curtailed at some points.”

Keith Taylor, an assistant economic development specialist in cooperative extension in the Department of Human Ecology, explained that there were multiple causes behind the power outages. One of these causes is that there is no requirement for stockpiled energy resources. While the absence of this requirement helps keep costs down, it also means that the grid is not well prepared for disasters. 

In addition, Texas’ power grid is isolated from the two major American grids, according to Bushnell. For example, California is much more integrated with neighboring states compared to Texas. Although the two states differ in the types of energy they use, both rely on natural gas to sustain operations. Because of this, Taylor explained that since Texas was not able to pull more capacity from the electric grid, it could have pulled more from the natural gas pipelines feeding into Texas if more were connected to other states.

In order to avoid such issues from occurring again, Taylor expressed the need for the weatherization of power generators, along with the hardening of the transmission infrastructure which facilitates the delivery of energy from power plants to consumers. 

“[This event] certainly revealed that all energy sources have an array of vulnerabilities. We need to harden the system for the entire mix of energy sources,” Taylor said.

Although this specific event was concentrated in the Southern U.S., power outages have also occurred in California in conjunction with strong winds and high temperatures this past year. Bushnell expressed that as climate change causes more extreme swings in weather patterns, the swings themselves are expected to increase in severity. 

“The lesson from the last 12 months in both California and Texas is that electricity systems can, in turn, expect larger swings in both demand and available supply as a result,” Bushnell said. “In California, the increasing share of renewable generation creates further correlation between weather and supply, but Texas demonstrates that this correlation can impact natural gas as well.”

Bushnell explained that policymakers should examine the natural gas market and the pipeline systems moving forward. Furthermore, he emphasized the importance of reconsidering the way the reliability of electricity systems is assessed. 

“The traditional approach to reliability planning in electricity is to target generation ‘capacity’—that is the maximum a plant can produce if all goes well,” Bushnell said. “As we rely more and more on alternative resources such as renewables, batteries, as well as hydro and even natural gas sometimes, the problem is not one of capacity at all but rather the ability of that capacity to produce electricity when we need it.”

Written by: Michelle Wong — science@theaggie.org