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

Keep Exploring

Discover More Topics From OCHMO Standards

Human Spaceflight Standards

The Human Spaceflight & Aviation Standards Team continually works with programs to provide the best standards and implementation documentation to…

Aerospace Medical Certification Standard

This NASA Technical Standard provides medical requirements and clinical procedures designed to ensure crew health and safety and occupational longevity…

Aviation Medical Certification Standards

This document provides the standards and administrative procedures for the aviation medical certification of NASA aviation flight personnel. It ensures…

Technical Briefs

Technical Briefs are available for standards that offer technical data, background, and application notes for vehicle developers and medical professionals.…

Powered by WPeMatico

Get The Details…
Kim Lowe

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

Powered by WPeMatico

Get The Details…
Elizabeth R. Landau

NASA Opens New Challenge to Support Climate-Minded Business Models

NASA’s Sustainable Business Model Challenge is looking for entrepreneurs, startups, and researchers to leverage the agency’s publicly available Earth system science data to develop commercial solutions for climate challenges.

This opportunity, with a submission deadline of June 13, bridges the gap between vast climate data and actionable solutions by inviting solvers to transform data into sustainable business models that support climate resilience and decision-making.

“Creative, outcome-driven entrepreneurs are the lifeblood of our country’s economy, and we’re excited to see the sustainable climate solutions they’re able to come up with when working closely with NASA’s vast resources and data,” said Jason L. Kessler, program executive for the NASA Small Business Innovation Research / Small Business Technology Transfer (SBIR/STTR) program, which is sponsoring the challenge.

Through the Sustainable Business Model Challenge, NASA aims to foster a new set of sustainable enterprises capable of turning climate insights into tangible market-ready services, ultimately contributing to a more resilient future for vulnerable communities, businesses, and ecosystems. NASA is committed to broadening participation in its solicitations and fostering technology advancements.

By engaging new entrepreneurs, the challenge serves as a pathway to NASA’s SBIR/STTR program, helping scale solutions to advance the global response to climate change and encourage a more sustainable future. From its vantage point in space, NASA holds a wealth of data that can inform new approaches to climate adaptation and mitigation.

Participants will submit a 10-page business concept paper that includes details on how they will incorporate NASA climate or Earth system data to deliver a product or service. Up to ten winning teams will receive $10,000 each, along with admission to a 10-week capability development training designed to strengthen any future proposals for potential NASA funding.

NASA’s SBIR/STTR program, managed by the agency’s Space Technology Mission Directorate, is part of America’s Seed Fund, the nation’s largest source of early-stage funding for innovative technologies. Through this program, entrepreneurs, startups, and small businesses with less than 500 employees can receive funding and non-monetary support to build, mature, and commercialize their technologies, advancing NASA missions and advancing the nations aerospace economy.

Ensemble is hosting the challenge on behalf of NASA. The NASA Tournament Lab, part of the Prizes, Challenges, and Crowdsourcing program in the Space Technology Mission Directorate, manages the challenge. The program supports global public competitions and crowdsourcing as tools to advance NASA research and development and other mission needs.

The deadline to participate in NASA’s Sustainable Business Model Challenge is June 13, 2025.

For more information about the challenge, visit: https://nasabusinesschallenge.org/ 

Powered by WPeMatico

Get The Details…
Sarah Douglas

NASA’s Planetary Defenders Head to the Sundance Film Festival

NASA is bringing the high-stakes world of planetary defense to the Sundance Film Festival, highlighting its upcoming documentary, “Planetary Defenders,” during a panel ahead of its spring 2025 premiere on the agency’s streaming service.

“We’re thrilled that NASA is attending Sundance Film Festival for the first time – a festival renowned for its innovative spirit,” said Brittany Brown, director, NASA Office of Communications Digital and Technology Division, at the agency’s Headquarters in Washington. “Our participation represents a groundbreaking opportunity for NASA to engage with the film industry and share new avenues for collaborative storytelling. By connecting with the creative minds at the festival, we aim to inspire new narratives, explore new avenues for collaborative storytelling, and ignite a renewed sense of wonder in space exploration.”

The NASA+ film explores a compelling question: How would humanity respond if we discovered an asteroid headed for Earth? Far from science fiction, “Planetary Defenders” follows real-life astronomers and other experts as they navigate the challenges of asteroid detection and safeguarding our planet from potential hazards.

“NASA is home to some of the greatest stories ever told, and NASA’s new streaming platform NASA+ is dedicated to sharing these stories to inspire the next generation,” said Rebecca Sirmons, general manager and head of NASA+. “We are honored to host a panel at this year’s Sundance Film Festival discussing our upcoming NASA+ documentary “Planetary Defenders.”

The panel, entitled “You Bet Your Asteroid: NASA Has a Story to Tell,” will start at 1:30 p.m. MST on Sunday, Jan. 26, at the Filmmaker Lodge in the Elks Building, 550 Main St., 2nd Floor, Park City, Utah. The event will include a discussion about the film followed by a Q&A session. Attendees also will have the opportunity to meet NASA experts and some of the planetary defenders themselves.

Panelists include:

• Rebecca Sirmons, head of NASA+, NASA
• Scott Bednar, filmmaker and director, NASA 360/National Institute of Aerospace
• Jessie Wilde, filmmaker and director, NASA 360/National Institute of Aerospace
• Dr. Kelly Fast, acting planetary defense officer, NASA’s Planetary Defense Coordination Office
• David Rankin, senior survey operations specialist, Catalina Sky Survey
• Dr. Vishnu Reddy, professor of planetary sciences and director of the Space4 Center, University of Arizona

Media are encouraged to RSVP in advance and may request one-on-one interviews with NASA experts following the panel by contacting Karen Fox at karen.c.fox@nasa.gov.

Through NASA+, the agency is continuing its decades long tradition of sharing live events, original content, and the latest news while NASA works to improve life on Earth through innovation, exploration, and discovery for the benefit of all. The free, on-demand streaming service is available to download without a subscription on most major platforms via the NASA App on iOS and Android mobile and tablet devices, as well as streaming media players like Roku, Apple TV, and Fire TV.

To keep up with the latest news from NASA’s planetary defense program, visit:

https://www.nasa.gov/planetarydefense

-end-

Abbey Donaldson
Headquarters, Washington
202-358-1600
abbey.a.donaldson@nasa.gov

Powered by WPeMatico

Get The Details…
Jessica Taveau

Martin Luther King, Jr. Memorial

The Stone of Hope, a granite statue of civil rights movement leader Dr. Martin Luther King, Jr., is seen in this image from Jan. 5, 2025. The statue is part of the Martin Luther King, Jr. Memorial in Washington.

Dr. King inspired millions to answer the righteous call for racial equality and to build a world where every person is treated equally, with dignity and respect. NASA is committed to innovate for the benefit of humanity and to inspire the world through discovery.

Image credit: NASA/Bill Ingalls

Powered by WPeMatico

Get The Details…
Monika Luabeya