After 60 Years, Nuclear Power for Spaceflight is Still Tried and True

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After 60 Years, Nuclear Power for Spaceflight is Still Tried and True

Editor’s Note: Originally published on June 21, 2021.

Six decades after the launch of the first nuclear-powered space mission, Transit IV-A, NASA is embarking on a bold future of human exploration and scientific discovery. This future builds on a proud history of safely launching and operating nuclear-powered missions in space.

“Nuclear power has opened the solar system to exploration, allowing us to observe and understand dark, distant planetary bodies that would otherwise be unreachable. And we’re just getting started,” said Dr. Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “Future nuclear power and propulsion systems will help revolutionize our understanding of the solar system and beyond and play a crucial role in enabling long-term human missions to the Moon and Mars.”

From Humble Beginnings: Nuclear Power Spawns an Age of Scientific Discovery

On June 29, 1961, the John’s Hopkins University Applied Physics Laboratory launched the Transit IV-A Spacecraft. It was a U.S. Navy navigational satellite with a SNAP-3B radioisotope powered generator producing 2.7 watts of electrical power — about enough to light an LED bulb. Transit IV-A broke an APL mission-duration record and confirmed the Earth’s equator is elliptical. It also set the stage for ground-breaking missions that have extended humanity’s reach across the solar system.

Since 1961, NASA has flown more than 25 missions carrying a nuclear power system through a successful partnership with the Department of Energy (DOE), which provides the power systems and plutonium-238 fuel.

“The department and our national laboratory partners are honored to play a role in powering NASA’s space exploration activities,” said Tracey Bishop, deputy assistant secretary in DOE’s Office of Nuclear Energy. “Radioisotope Power Systems are a natural extension of our core mission to create technological solutions that meet the complex energy needs of space research, exploration, and innovation.”

There are only two practical ways to provide long-term electrical power in space: the light of the sun or heat from a nuclear source.

We couldn’t do the mission without it. No other technology exists to power a mission this far away from the Sun, even today.

Alan Stern

Principal Investigator, NASA’s New Horizons Mission to Pluto and Beyond

“As missions move farther away from the Sun to dark, dusty, and harsh environments, like Jupiter, Pluto, and Titan, they become impossible or extremely limited without nuclear power,” said Leonard Dudzinski, chief technologist for NASA’s Planetary Science Division and program executive for Radioisotope Power.

That’s where Radioisotope Power Systems, or RPS, come in. They are a category of power systems that convert heat generated by the decay of plutonium-238 fuel into electricity.

“These systems are reliable and efficient,” said June Zakrajsek, manager for NASA’s Radioisotope Power Systems Program office at Glenn Research Center in Cleveland. “They operate continuously over long-duration space missions regardless of sunlight, temperature, charged particle radiation, or surface conditions like thick clouds or dust. They’ve allowed us to explore from the Sun to Pluto and beyond.”

RPS powered the Apollo Lunar Surface Experiment Package. They’ve sustained Voyager 1 and 2 since 1977, and they kept Cassini-Huygens’ instruments warm as it explored frigid Saturn and its moon Titan.

Today, a Multi-Mission Thermoelectric Generator (MMRTG) powers the Perseverance rover, which is captivating the nation as it searches for signs of ancient life on Mars, and a single RTG is sustaining New Horizons as it ventures on its way out of the solar system 15 years after its launch.

“The RTG was and still is crucial to New Horizons,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute. “We couldn’t do the mission without it. No other technology exists to power a mission this far away from the Sun, even today.”

Great Things to Come: Science and Human Exploration

Dragonfly, which is set to launch in 2028, is the next mission with plans to use an MMRTG. Part of NASA’s New Frontiers program, Dragonfly is an octocopter designed to explore and collect samples on Saturn’s largest moon, Titan, an ocean world with a dense, hazy atmosphere.

“RPS is really an enabling technology,” said APL’s Zibi Turtle, principal investigator for the upcoming Dragonfly mission. “Early missions like Voyager, Galileo, and Cassini that relied on RPS have completely changed our understanding and given us a geography of the distant solar system…Cassini gave us our first close-up look at the surface of Titan.”

According to Turtle, the MMRTG serves two purposes on Dragonfly: power output to charge the lander’s battery and waste heat to keep its instruments and electronics warm.

“Flight is a very high-power activity. We’ll use a battery for flight and science activities and recharge the battery using the MMRTG,” said Turtle. “The waste heat from the power system is a key aspect of our thermal design. The surface of Titan is very cold, but we can keep the interior of the lander warm and cozy using the heat from the MMRTG.”

As the scientific community continues to benefit from RPS, NASA’s Space Technology Mission Directorate is investing in new technology using reactors and low-enriched uranium fuel to enable a robust human presence on the Moon and eventually human missions to Mars.

Astronauts will need plentiful and continuous power to survive the long lunar nights and explore the dark craters on the Moon’s South Pole. A fission surface power system could provide enough juice to power robust operations. NASA is leading an effort, working with the DOE and industry to design a fission power system for a future lunar demonstration that will pave the way for base camps on the Moon and Mars.

NASA has also thought about viable ways to reduce the time it takes to travel to Mars, including nuclear propulsion systems.

As NASA advances its bold vision of exploration and scientific discovery in space, it benefits from 60 years of the safe use of nuclear power during spaceflight. Sixty years of enlightenment that all started with a little satellite called Transit IV-A.

News Media Contact
Jan Wittry
NASA’s Glenn Research Center

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Submit Your 2025 Event Proposal to NASA

NASA is making event plans for the 2025 calendar year, and we want to pencil you in! We are looking for the Midwest’s biggest and best community events with the broadest audiences to share NASA’s content and raise awareness of the agency’s most exciting aeronautics and space missions. NASA’s Glenn Research Center in Cleveland is leading the agency’s efforts to inspire the Midwest through engagement.

Learn How to Submit a Proposal

Interested organizations can submit an event proposal to Glenn now through Nov. 18, 2024. Those selected will receive notification via email by Dec. 31, 2024. Through this collaboration, selected organizations will gain access to NASA exhibits and artifacts, hands-on demonstrations, STEM and internship opportunities for students and educators, NASA’s innovative technology, and experts that align to the topics and themes of their events.

Eligibility Requirements

NASA is seeking:

• Organizations with direct community connections and an established event that reaches diverse audiences. 
• Events scheduled to occur between Jan. 1, 2025, and Dec. 31, 2025.
• Events that are mutually beneficial – where a NASA presence will enhance the event experience and raise awareness of NASA’s contributions to the advancement of aeronautics and space exploration.

Selected organizations must agree to the following:

• Attend virtual planning meetings through an online business communication platform.
• Work with NASA Glenn’s Office of Communications when coordinating marketing, media communications, and logistics as described in the event proposal.
• Adhere to NASA Media Usage Guidelines for NASA media and logos.
• Provide final attendance data within two weeks of the conclusion of the event including the following:
  • Number of attendees
  • Estimated percentage of attendees from underrepresented audiences

Submitting a Proposal

All proposals are to be submitted through the online proposal form. Proposals must be submitted by 11:59 p.m. Eastern on Nov. 18, 2024. Only proposals submitted online will be accepted.

Proposal Review Process

Proposals will be evaluated and scored, and selections will be made using the following criteria:

• Estimated audience size.
• Percentage of audience from underserved and/or underrepresented communities as defined below.
  • For purposes of this solicitation, underserved and/or underrepresented communities include Black, Latino, and Indigenous and Native American persons, Asian Americans and Pacific Islanders and other persons of color; members of religious minorities; lesbian, gay, bisexual, transgender, and queer (LGBTQ+) persons; persons with disabilities; persons who live in rural areas; and persons otherwise adversely affected by persistent poverty or inequality. (Source: NASA’s Mission Equity).
• Alignment of the program’s goals and objectives to those of this opportunity.
• Plans to maximize audience participation through marketing and media communications.
• Evidence of historical attendance at this or similar events hosted by the proposing organization.

Proposing organizations will be notified of their selection status by Dec. 31, 2024.

Point of Contact

If you have questions about this opportunity or the online proposal form, contact NASA Glenn’s Office of Communications: GRC-Public-Engagement@mail.nasa.gov.

Timeline

Solicitation posted: Oct. 23, 2024
Proposal form URL: https://osirris.grc.nasa.gov/request/request.cfm
Proposal submission deadline: Nov. 18, 2024
Notification of event selection: Dec. 13, 2024 

Background

NASA’s Glenn Research Center designs, develops, and tests innovative technology to revolutionize air travel, advance space exploration, and improve life on Earth. As one of 10 NASA centers, and the only one in the Midwest, Glenn is a vital contributor to the region’s economy and culture. Many NASA missions have Glenn contributions, and every U.S. aircraft has NASA Glenn technology on board, making flight cleaner, safer, and quieter.

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Kelly M. Matter

NASA Begins New Deployable Solar Array Tech Demo on Pathfinder Spacecraft

NASA recently evaluated initial flight data and imagery from Pathfinder Technology Demonstrator-4 (PTD-4), confirming proper checkout of the spacecraft’s systems including its on-board electronics as well as the payload’s support systems such as the small onboard camera. Shown above is a test image of Earth taken by the payload camera, shortly after PTD-4 reached orbit. This camera will continue photographing the technology demonstration during the mission. 

Payload operations are now underway for the primary objective of the PTD-4 mission – the demonstration of a new power and communications technology for future spacecraft. The payload, a deployable solar array with an integrated antenna called the Lightweight Integrated Solar Array and anTenna, or LISA-T, has initiated deployment of its central boom structure. The boom supports four solar power and communication arrays, also called petals. Releasing the central boom pushes the still-stowed petals nearly three feet (one meter) away from the spacecraft bus. The mission team currently is working through an initial challenge to get LISA-T’s central boom to fully extend before unfolding the petals and beginning its power generation and communication operations.

Small spacecraft on deep space missions require more electrical power than what is currently offered by existing technology. The four-petal solar array of LISA-T is a thin-film solar array that offers lower mass, lower stowed volume, and three times more power per mass and volume allocation than current solar arrays. The in-orbit technology demonstration includes deployment, operation, and environmental survivability of the thin-film solar array.  

“The LISA-T experiment is an opportunity for NASA and the small spacecraft community to advance the packaging, deployment, and operation of thin-film, fully flexible solar and antenna arrays in space. The thin-film arrays will vastly improve power generation and communication capabilities throughout many different mission applications,” said Dr. John Carr, deputy center chief technologist at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “These capabilities are critical for achieving higher value science alongside the exploration of deep space with small spacecraft.”

The Pathfinder Technology Demonstration series of missions leverages a commercial platform which serves to test innovative technologies to  increase the capability of small spacecraft. Deploying LISA-T’s thin solar array in the harsh environment of space presents inherent challenges such as deploying large highly flexible non-metallic structures with high area to mass ratios. Performing experiments such as LISA-T on a smaller, lower-cost spacecraft allows NASA the opportunity to take manageable risk with high probability of great return. The LISA-T experiment aims to enable future deep space missions with the ability to acquire and communicate data through improved power generation and communication capabilities on the same integrated array.

The PTD-4 small spacecraft is hosting the in-orbit technology demonstration called LISA-T. The PTD-4 spacecraft deployed into low Earth orbit from SpaceX’s Transporter-11 rocket which launched from Space Launch Complex 4E at Vandenberg Space Force Base in California on Aug. 16. NASA’s Marshall Space Flight Center in Huntsville, Alabama designed and built the LISA-T technology as well as LISA-T’s supporting avionics system. NASA’s Small Spacecraft Technology program, based at NASA’s Ames Research Center in California’s Silicon Valley and led by the agency’s Space Technology Mission Directorate, funds and manages the PTD-4 mission as well as the overall Pathfinder Technology Demonstration mission series. Terran Orbital Corporation of Irvine, California, developed and built the PTD-4 spacecraft bus, named Triumph.

Learn more about NASA’s LISA-T technology:

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Gianine Figliozzi

NASA Stennis Takes Key Step in Expanding its Range Operations Work

NASA’s Stennis Space Center near Bay St. Louis, Mississippi, has entered into an agreement with Skydweller Aero Inc. for the company to operate its solar-powered autonomous aircraft in the site’s restricted airspace, a key step towards achieving a strategic center goal.

The Reimbursable Space Act agreement marks the first between NASA Stennis and a commercial company to utilize the south Mississippi center’s unique capabilities to support testing and operation of uncrewed systems.

“There are few locations like NASA Stennis that offer a secure location, restricted airspace and the infrastructure to support testing and operation of various uncrewed systems,” said NASA Stennis Director John Bailey. “Range operations is a critical area of focus as we adapt to the changing aerospace and technology landscape to grow into the future.”

NASA Stennis and Skydweller Aero finalized the agreement in late August, paving the way for the company to begin area test flights of its autonomous, uncrewed solar-powered aircraft, which features a wingspan greater than a 747 jetliner and is designed for long-duration flights. The company announced Oct. 1 it had completed an initial test flight campaign of the aircraft, including two test excursions totaling 16 and 22.5 hours.

NASA Stennis and Skydweller Aero began talks in the summer of 2023 when the company expressed interest in utilizing NASA Stennis airspace for its all-carbon fiber aircraft. The NASA Stennis area fits the company’s needs well since it provides ready access from Stennis International Airport to the Gulf of Mexico area. NASA Stennis airspace also provides a level of privacy for aircraft testing and operation.

“Access to the restricted airspace above NASA Stennis has been tremendously helpful to our uncrewed, autonomous flight operations,” said Barry Matsumori, president and chief operating officer of Skydweller Aero. “The opportunity to use the controlled environment above Stennis helps accelerate our efforts, allowing us to transition the aircraft in and out of civil airspace, while demonstrating its reliability and unblemished safety record to the FAA.”

Companies must be conducting public aircraft operations to use any restricted airspace. In this instance, Skydweller Aero is flying its aircraft in association with the U.S. Department of Defense, allowing for the Reimbursable Space Act agreement with NASA Stennis.

The agreement provides the company Federal Aviation Administration (FAA) authorization for future test flights in designated areas of the NASA Stennis buffer zone. It also represents a key step in the center’s effort to grow its range operations presence.

“This really opens the door for others to come here,” said Jason Peterson, NASA Stennis range officer. “There are requirements that must be met, but for those who meet them, NASA Stennis is an ideal location for test and flight operations.”

The FAA established restricted airspace at NASA Stennis in 1966 and approved its expansion in 2016. The expansion was necessary to conduct propulsion testing safely, accommodate U.S. Department of Defense missions, and support unmanned aerial systems activities.

Restricted airspace at NASA Stennis allows qualifying organizations to conduct various uncrewed flight activities. NASA Stennis personnel provide scheduling and range operation support, including reviews and evaluations to ensure safe flight operations. Processes are in place to ensure communication between aircraft operators, FAA air traffic controllers, and range safety personnel.

Peterson said he hopes the agreement with Skydweller Aero will clear the way for future collaborations as NASA Stennis continues to expand its customer-based operations. For instance, although Skydweller Aero is not located onsite, NASA Stennis is able to support ground operations for a variety of unmanned aircraft system takeoffs and landings.

Beyond that, the center also hopes to expand its operational capabilities to include marine and ground activities. In addition to a large geographic footprint, the center features a secure 7.5-mile waterway canal system for testing unmanned underwater or surface vehicles.

For information about range operations at NASA’s Stennis Space Center, visit:

Range and Airspace Operations – NASA

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LaToya Dean

NASA Quiet Space Fan Research to Benefit Commercial Space Stations

NASA researchers developed a Quiet Space Fan to reduce the noise inside crewed spacecraft, sharing the results with industry for potential use on future commercial space stations.

Controlling noise inside spacecraft helps humans talk to each other, hear alarms clearer, get restful sleep, and minimizes the risk of hearing loss. It is best to control the noise at the source, and in spacecraft the noise often comes from cabin ventilation and equipment cooling fans.

Since the earliest days of human spaceflight, there has been noise from the Environmental Control and Life Support System ventilation. NASA is working to design highly efficient and quiet fans by building on technology initially developed at the agency’s Glenn Research Center in Cleveland and sharing it with companies that are developing new spacecraft and space stations.

“As NASA continues to support the design and development of multiple commercial space stations, we have intentional and focused efforts to share technical expertise, technologies, and data with industry,” said Angela Hart, manager of NASA’s Commercial Low Earth Orbit Development Program at the agency’s Johnson Space Center in Houston. “The Quiet Space Fan research is one more example of how we are actively working with private companies to foster the development of future destinations.”

The initial fan prototype was designed at Glenn in 2009 using tools developed for aircraft turbofan engines. The fan design size, flow rate – how much air the fan moves – and pressure rise – the increase in pressure across the fan – were designed similarly to the original Orion cabin fan design point (150 cubic feet per minute, 3.64 inches of water column). Acoustic measurements showed that the new design was approximately 10 decibels quieter than a similar-sized commercial off-the-shelf fan.

To take the research a step further, a larger fan was recently designed with almost twice the flow rate and pressure rise capability (250 cubic feet per minute, 7 inches of water column) compared to the initial prototype. For example, the original fan could provide enough airflow for a large car or van, and the larger fan could provide enough airflow for a house.

NASA’s quiet fan design aims to maintain high performance standards while significantly reducing everyday noise levels and can potentially be used on the International Space Station and future commercial destinations.

“This work will lead to significant benefits including volume and mass savings from noise controls that are no longer as large or needed at all, reduced system pressure loss from mufflers and silencers that don’t need to be as restrictive, reduced power draw because of the reduced system pressure loss and the highly efficient fan design, and satisfying spaceflight vehicle acoustic requirements to provide a safe and habitable acoustic environment for astronauts,” said Chris Allen, Acoustics Office manager at NASA Johnson.

Developing quieter fans is one of many efforts NASA is making to improve human spaceflight and make space exploration more innovative and comfortable for future missions to low Earth orbit. Helping private companies provide reliable and safe services at a lower cost will allow the agency to focus on Artemis missions to the Moon while continuing to use low Earth orbit as a training and proving ground for deep space missions.

Learn more about NASA’s commercial space strategy at:

https://www.nasa.gov/humans-in-space/commercial-space

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Roger Weiss