Station Science Top News: Jan. 17, 2025

Insights into metal alloy solidification

Researchers report details of phase and structure in the solidification of metal alloys on the International Space Station, including formation of microstructures. Because these microstructures determine a material’s mechanical properties, this work could support improvements in techniques for producing coatings and additive manufacturing or 3D printing processes.

METCOMP, an ESA (European Space Agency) investigation, studied solidification in microgravity using transparent organic mixtures as stand-ins for metal alloys. Conducting the research in microgravity removed the influence of convection and other effects of gravity. Results help scientists better understand and validate models of solidification mechanisms, enabling better forecasting of microstructures and improving manufacturing processes.

Measuring the height of upper-atmospheric electrical discharges

Researchers determined the height of a blue discharge from a thundercloud using ground-based electric field measurements and space-based optical measurements from Atmosphere-Space Interactions Monitor (ASIM). This finding helps scientists better understand how these high-altitude lightning-related events affect atmospheric chemistry and could help improve atmospheric models and climate and weather predictions.

ESA’s ASIM is an Earth observation facility that studies severe thunderstorms and upper-atmospheric lighting events and their role in the Earth’s atmosphere and climate. Upper-atmospheric lightning, also known as transient luminous events, occurs well above the altitudes of normal lightning and storm clouds. The data collected by ASIM could support research on the statistical properties of many upper atmosphere lightning events, such as comparison of peak intensities of blue and red pulses with reports from lightning detection networks.

Modeling a complex neutron star

Scientists report that they can use modeling of neutron star PSRJ1231−1411’s X-ray pulses to infer its mass and radius and narrow the possible behaviors of the dense matter at its core. This finding provides a better understanding of the composition and structure of these celestial objects, improving models that help answer questions about conditions in the universe.

The Neutron star Interior Composition Explorer provides high-precision measurements of pulses of X-ray radiation from neutron stars. This particular neutron star presented challenges in finding a fit between models and data, possibly due to fundamental issues with its pulse profile. The authors recommend a program of simulations using synthetic data to determine whether there are fundamental issues with this type of pulse profile that could prevent efforts to obtain tighter and more robust constraints.

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Sumer Loggins

NASA Sets Sights on Mars Terrain with Revolutionary Tire Tech

The mystique of Mars has been studied for centuries. The fourth planet from the Sun is reminiscent of a rich, red desert and features a rugged surface challenging to traverse. While several robotic missions have landed on Mars, NASA has only explored 1% of its surface. Ahead of future human and robotic missions to the Red Planet, NASA recently completed rigorous rover testing on Martian-simulated terrain, featuring revolutionary shape memory alloy spring tire technology developed at the agency’s Glenn Research Center in Cleveland in partnership with Goodyear Tire & Rubber.

Rovers — mobile robots that explore lunar or planetary surfaces — must be equipped with adequate tires for the environments they’re exploring. As Mars has an uneven, rocky surface, durable tires are essential for mobility. Shape memory alloy (SMA) spring tires help make that possible.

Shape memory alloys are metals that can return to their original shape after being bent, stretched, heated, and cooled. NASA has used them for decades, but applying this technology to tires is a fairly new concept.

“We at Glenn are one of the world leaders in bringing the science and understanding of how you change the alloy compositions, how you change the processing of the material, and how you model these systems in a way that we can control and stabilize the behaviors so that they can actually be utilized in real applications,” said Dr. Santo Padula II, materials research engineer at NASA Glenn.

Padula and his team have tested several applications for SMAs, but his epiphany of the possibilities for tires came about because of a chance encounter.

While leaving a meeting, Padula encountered Colin Creager, a mechanical engineer at NASA Glenn whom he hadn’t seen in years. Creager used the opportunity to tell him about the work he was doing in the NASA Glenn Simulated Lunar Operations (SLOPE) Laboratory, which can simulate the surfaces of the Moon and Mars to help scientists test rover performance. He brought Padula to the lab, where Padula immediately took note of the spring tires. At the time, they were made of steel.

Padula remarked, “The minute I saw the tire, I said, aren’t you having problems with those plasticizing?” Plasticizing refers to a metal undergoing deformation that isn’t reversible and can lead to damage or failure of the component.

“Colin told me, ‘That’s the only problem we can’t solve.’” Padula continued, “I said, I have your solution. I’m developing a new alloy that will solve that. And that’s how SMA tires started.”

From there, Padula, Creager, and their teams joined forces to improve NASA’s existing spring tires with a game-changing material: nickel-titanium SMAs. The metal can accommodate deformation despite extreme stress, permitting the tires to return to their original shape even with rigorous impact, which is not possible for spring tires made with conventional metal.

Since then, research has been abundant, and in the fall of 2024, teams from NASA Glenn traveled to Airbus Defence and Space in Stevenage, United Kingdom, to test NASA’s innovative SMA spring tires. Testing took place at the Airbus Mars Yard — an enclosed facility created to simulate the harsh conditions of Martian terrain.

“We went out there with the team, we brought our motion tracking system and did different tests uphill and back downhill,” Creager said. “We conducted a lot of cross slope tests over rocks and sand where the focus was on understanding stability because this was something we had never tested before.”

During the tests, researchers monitored rovers as the wheels went over rocks, paying close attention to how much the crowns of the tires shifted, any damage, and downhill sliding. The team expected sliding and shifting, but it was very minimal, and testing met all expectations. Researchers also gathered insights about the tires’ stability, maneuverability, and rock traversal capabilities.

As NASA continues to advance systems for deep space exploration, the agency’s Extravehicular Activity and Human Surface Mobility program enlisted Padula to research additional ways to improve the properties of SMAs for future rover tires and other potential uses, including lunar environments.

“My goal is to extend the operating temperature capability of SMAs for applications like tires, and to look at applying these materials for habitat protection,” Padula said. “We need new materials for extreme environments that can provide energy absorption for micrometeorite strikes that happen on the Moon to enable things like habitat structures for large numbers of astronauts and scientists to do work on the Moon and Mars.”

Researchers say shape memory alloy spring tires are just the beginning.

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Kelly M. Matter

Hydrogen Sulfide (H2S) Independent Assessment

The goals of the working group were to:

1. Endorse or recommend changes to H2S SMAC levels that had been proposed by the JSC Toxicology Laboratory
2. Review a draft H2S SMAC manuscript prepared by the JSC Toxicology Laboratory
3. Provide any additional insight and consideration regarding H2S toxicity that should be considered for spaceflight programs

Background

The NASA Spaceflight Human-System Standard (NASA-STD-3001) establishes that vehicle systems shall limit atmospheric contamination below established limits [V2 6050] Atmosphere Contamination Limit. The JSC Toxicology Laboratory maintains the JSC 20584 Spacecraft Maximum Allowable Concentrations for Airborne Contaminants document, which contains a table of SMAC values for a variety of chemicals including carbon monoxide, ammonia, heavy metals, and a wide range of volatile organic compounds. SMACs are documented for 1-hr, 24-hr, 7-day, 30-day, 180-day, and 1000-day time spans for each chemical, and express the maximum concentration to which spaceflight crew can be exposed for that duration.

The organ system that is affected as well as the effect (symptoms) are also documented for each SMAC. For more information on SMACs, see this article Exposure Guidelines (SMACs and SWEGs) – NASA and the OCHMO Spaceflight Toxicology technical brief technical brief.

A SMAC value for hydrogen sulfide has not previously been established since it has not been of concern in spacecraft. However, with Artemis missions returning to the moon there is a possibility that H₂S could be released within spacecraft during lunar sample return, given that this compound may be a component of lunar polar ice. H₂S has an intense smell of rotten eggs and therefore has a distracting psychological element. Physiologically it has been shown to be an irritant at low concentrations and in high concentrations can potentially lead to neurological effects and unconsciousness.

Hydrogen sulfide SMAC values will define safe limits for spaceflight crews on future missions and could drive new requirements for monitoring and mitigation of this chemical during spaceflight.

Conclusions

Key points of the review were:

1. The proposed 1-hour, 24-hour, 7-day, 30-day, and 180-day SMAC values were deemed appropriate and were endorsed by each of the panel members.
2. The proposed 1000-day SMAC value is so low that the panel’s opinion is that this SMAC may not be attainable due to human-generated sources, and that these concentrations do not represent a true toxicological risk. The recommendation is to eliminate the 1000-day SMAC, or to call it a guideline.
3. The general SMAC calculation approach and inclusion of safety factors is logical, although some additional rationale would be justified.
4. Interactive and additive effects with other substances are considered negligible, particularly at these low concentrations.
5. Microgravity-induced physiological changes are unlikely to exacerbate hydrogen sulfide exposure at these low concentrations.
6. Recommendations were made with the understanding that these SMACs apply to pre-screened, healthy astronauts. For private spaceflight participants who may not be as well screened, the panel recommended individual physician attention and a review of all SMACs (including hydrogen sulfide), to identify sensitivities in certain populations (existing disease states, etc.).
7. Passive dosimetry technology is available and should be considered for long-term monitoring at these low concentrations.

Following consideration of the panel’s recommendation, the NASA/TM-20240000101 Exposure Limits for Hydrogen Sulfide in Spaceflight was revised and released by the JSC toxicology group in January of 2024 and is available below.

About the Author

Kim Lowe

Human Systems Standards Integrator

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NASA Scientists, Engineers Receive Presidential Early Career Awards 

President Biden has named 19 researchers who contribute to NASA’s mission as recipients of the Presidential Early Career Award for Scientists and Engineers (PECASE). These recipients are among nearly 400 federally funded researchers receiving the honor.  

Established in 1996 by the National Science and Technology Council, the PECASE Award is the highest honor given by the U.S. government to scientists and engineers who are beginning their research careers. The award recognizes recipients’ potential to advance the frontiers of scientific knowledge and their commitment to community service, as demonstrated through professional leadership, education or community outreach. 

“I am so impressed with these winners and what they have accomplished,” said Kate Calvin, chief scientist, NASA Headquarters in Washington. “They have made valuable contributions to NASA science and engineering, and I can’t wait to see what they do in the future.” 

The following NASA recipients were nominated by the agency: 

• Natasha Batalha, NASA Ames Research Center, Silicon Valley, California – for transformational scientific research in the development of open-source systems for the modeling of exoplanet atmospheres and observations 

• Elizabeth Blaber, Rensselaer Polytechnic Institute, Troy, New York – for transformative spaceflight and ground-based space biology research 

• James Burns, University of Virginia, Charlottesville – for innovative research at the intersection of metallurgy, solid mechanics and chemistry  

• Egle Cekanaviciute, NASA Ames Research Center – for producing transformational research to enable long-duration human exploration on the Moon and Mars 

• Nacer Chahat, NASA Jet Propulsion Laboratory, Pasadena, California – for leading the innovation of spacecraft antennas that enable NASA deep space and earth science missions 

• Ellyn Enderlin, Boise State University, Idaho – for innovative methods to study glaciers using a wide variety of satellite datasets 

• David Estrada, Boise State University, Idaho – for innovative research in the areas of printed electronics for in space manufacturing and sensors for harsh environments 

• Burcu Gurkan, Case Western Reserve University, Cleveland, Ohio – for transforming contemporary approaches to energy storage and carbon capture to be safer and more economical, for applications in space and on Earth 

• Elliott Hawkes, University of California, Santa Barbara – for highly creative innovations in bio-inspired robotics that advance science and support NASA’s mission 

• John Hwang, University of California, San Diego – for innovative approach to air taxi design and key contributions to the urban air mobility industry  

• James Tuttle Keane, NASA Jet Propulsion Laboratory – for innovative and groundbreaking planetary geophysics research, and renowned planetary science illustrations 

• Kaitlin Kratter, University of Arizona, Tucson – for leadership in research about the formation and evolution of stellar and planetary systems beyond our own  

• Lyndsey McMillon-Brown, NASA Glenn Research Center, Cleveland, Ohio – for leadership in photovoltaic research, development, and demonstrations 

• Debbie Senesky, Stanford University, California – for research that has made it possible to operate sensing and electronic devices in high-temperature and radiation-rich environments 

• Hélène Seroussi, Dartmouth College, Hanover, New Hampshire  – for leading the cryosphere science community in new research directions about the role of ocean circulation in the destabilization of major parts of Antarctica’s ice sheets 

• Timothy Smith, NASA Glenn Research Center – for achievements in materials science research, specifically in high temperature alloy innovation 

• Mitchell Spearrin, University of California, Los Angeles – for pioneering scientific and technological advancements in multiple areas critical to NASA’s current and future space missions including rocket propulsion, planetary entry, and sensor systems 

• Michelle Thompson, Purdue University, West Lafayette, Indiana  – for research in planetary science and dedication to training the next generation of STEM leaders 

• Mary Beth Wilhelm, NASA Ames Research Center – for achievements in science, technology, and community outreach through her work in the fields of space science and astrobiology 

The PECASE awards were created to highlight the importance of science and technology for America’s future. These early career awards foster innovative developments in science and technology, increase awareness of careers in science and engineering, provide recognition to the scientific missions of participating agencies, and enhance connections between research and challenges facing the nation. For a complete list of award winners, visit: 

https://www.whitehouse.gov/ostp/news-updates/2025/01/14/president-biden-honors-nearly-400-federally-funded-early-career-scientists

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Elizabeth R. Landau