Jesse Rhoades, University of North Dakota and Rebecca Rhoades, University of North Dakota Humans will likely set foot on the Moon again in the coming decade. While many stories in this new chapter of lunar exploration will be reminiscent of the Apollo missions 50 years ago, others may look quite different. For instance, the European Space Agency is currently working to make space travel more accessible for people of a wide range of backgrounds and abilities. In this new era, the first footprint on the Moon could possibly be made by a prosthetic limb.

Historically, and even still today, astronauts selected to fly to space have had to fit a long list of physical requirements. However, many professionals in the field are beginning to acknowledge that these requirements stem from outdated assumptions. Some research, including studies by our multidisciplinary team of aerospace and biomechanics researchers, has begun to explore the possibilities for people with physical disabilities to venture into space, visit the Moon and eventually travel to Mars.

Current research

NASA has previously funded and is currently funding research on restraints and mobility aids to help everyone, regardless of their ability, move around in the crew cabin. Additionally, NASA has research programs to develop functional aids for individuals with disabilities in current U.S. spacecraft. A functional aid is any device that improves someone’s independence, mobility or daily living tasks by compensating for their physical limitations. The European Space Agency, or ESA, launched its Parastronaut Feasibility Project in 2022 to assess ways to include individuals with disabilities in human spaceflight. A parastronaut is an astronaut with a physical disability who has been selected and trained to participate in space missions. At the University of North Dakota, we conducted one of the first studies focused on parastronauts. This research examined how individuals with disabilities get into and get out of two current U.S. spacecraft designed to carry crew. The first was NASA’s Orion capsule, designed by Lockheed Martin, and the second was Boeing’s CST 100 Starliner. Alongside our colleagues Pablo De León, Keith Crisman, Komal Mangle and Kavya Manyapu, we uncovered valuable insights into the accessibility challenges future parastronauts may face. Our research indicated that individuals with physical disabilities are nearly as nimble in modern U.S. spacecraft as nondisabled individuals. This work focused on testing individuals who have experienced leg amputations. Now we are looking ahead to solutions that could benefit astronauts of all abilities.

Safety and inclusion

John McFall is the ESA’s first parastronaut. At the age of 19, Mcfall lost his right leg just above the knee from a motorcycle accident. Although McFall has not been assigned to a mission yet, he is the first person with a physical disability to be medically certified for an ISS mission.

Astronaut selection criteria currently prioritize peak physical fitness, with the goal of having multiple crew members who can do the same physical tasks. Integrating parastronauts into the crew has required balancing mission security and accessibility. However, with advancements in technology, spacecraft design and assistive tools, inclusion no longer needs to come at the expense of safety. These technologies are still in their infancy, but research and efforts like the ESA’s program will help improve them. Design and development of spacecraft can cost billions of dollars. Simple adaptations, such as adding handholds onto the walls in a spacecraft, can provide vital assistance. However, adding handles to existing spacecraft will be costly. Functional aids that don’t alter the spacecraft itself – such as accessories carried by each astronaut – could be another way forward. For example, adding Velcro to certain spots in the spacecraft or on prosthetic limbs could improve a parastronaut’s traction and help them anchor to the spacecraft’s surfaces. Engineers could design new prosthetics made for particular space environments, such as zero or partial gravity, or even tailored to specific spacecraft. This approach is kind of like designing specialized prosthetics for rock climbing, running or other sports.

Accessibility can help everyone

Future space exploration, particularly missions to the Moon and Mars that will take weeks, months and even years, may prompt new standards for astronaut fitness. During these long missions, astronauts could get injured, causing what can be considered incidental disability. An astronaut with an incidental disability begins a mission without a recognized disability but acquires one from a mission mishap. An astronaut suffering a broken arm or a traumatic brain injury during a mission would have a persistent impairment.

During long-duration missions, an astronaut crew will be too far away to receive outside medical help – they’ll have to deal with these issues on their own. Considering disability during mission planning goes beyond inclusion. It makes the mission safer for all astronauts by preparing them for anything that could go wrong. Any astronaut could suffer an incidental disability during their journey. Safety and inclusion in spaceflight don’t need to be at odds. Instead, agencies can reengineer systems and training processes to ensure that more people can safely participate in space missions. By addressing safety concerns through technology, innovative design and mission planning, the space industry can have inclusive and successful missions. Jesse Rhoades, Professor of Education, Heath & Behavior, University of North Dakota and Rebecca Rhoades, Researcher in Education, Health & Behavior, University of North Dakota This article is republished from The Conversation under a Creative Commons license. Read the original article.

Benjamin Roulston, Clarkson University Powering spacecraft with solar energy may not seem like a challenge, given how intense the Sun’s light can feel on Earth. Spacecraft near the Earth use large solar panels to harness the Sun for the electricity needed to run their communications systems and science instruments. However, the farther into space you go, the weaker the Sun’s light becomes and the less useful it is for powering systems with solar panels. Even in the inner solar system, spacecraft such as lunar or Mars rovers need alternative power sources. As an astrophysicist and professor of physics, I teach a senior-level aerospace engineering course on the space environment. One of the key lessons I emphasize to my students is just how unforgiving space can be. In this extreme environment where spacecraft must withstand intense solar flares, radiation and temperature swings from hundreds of degrees below zero to hundreds of degrees above zero, engineers have developed innovative solutions to power some of the most remote and isolated space missions. So how do engineers power missions in the outer reaches of our solar system and beyond? The solution is technology developed in the 1960s based on scientific principles discovered two centuries ago: radioisotope thermoelectric generators, or RTGs. RTGs are essentially nuclear-powered batteries. But unlike the AAA batteries in your TV remote, RTGs can provide power for decades while hundreds of millions to billions of miles from Earth.

Nuclear power

Radioisotope thermoelectric generators do not rely on chemical reactions like the batteries in your phone. Instead, they rely on the radioactive decay of elements to produce heat and eventually electricity. While this concept sounds similar to that of a nuclear power plant, RTGs work on a different principle. Most RTGs are built using plutonium-238 as their source of energy, which is not usable for nuclear power plants since it does not sustain fission reactions. Instead, plutonium-238 is an unstable element that will undergo radioactive decay. Radioactive decay, or nuclear decay, happens when an unstable atomic nucleus spontaneously and randomly emits particles and energy to reach a more stable configuration. This process often causes the element to change into another element, since the nucleus can lose protons.

When plutonium-238 decays, it emits alpha particles, which consist of two protons and two neutrons. When the plutonium-238, which starts with 94 protons, releases an alpha particle, it loses two protons and turns into uranium-234, which has 92 protons. These alpha particles interact with and transfer energy into the material surrounding the plutonium, which heats up that material. The radioactive decay of plutonium-238 releases enough energy that it can glow red from its own heat, and it is this powerful heat that is the energy source to power an RTG.

Heat as power

Radioisotope thermoelectric generators can turn heat into electricity using a principle called the Seebeck effect, discovered by German scientist Thomas Seebeck in 1821. As an added benefit, the heat from some types of RTGs can help keep electronics and the other components of a deep-space mission warm and working well. In its basic form, the Seebeck effect describes how two wires of different conducting materials joined in a loop produce a current in that loop when exposed to a temperature difference.

Devices that use this principle are called thermoelectric couples, or thermocouples. These thermocouples allow RTGs to produce electricity from the difference in temperature created by the heat of plutonium-238 decay and the frigid cold of space.

Radioisotope thermoelectric generator design

In a basic radioisotope thermoelectric generator, you have a container of plutonium-238, stored in the form of plutonium-dioxide, often in a solid ceramic state that provides extra safety in the event of an accident. The plutonium material is surrounded by a protective layer of foil insulation to which a large array of thermocouples is attached. The whole assembly is inside a protective aluminum casing.

The interior of the RTG and one side of the thermocouples is kept hot – close to 1,000 degrees Fahrenheit (538 degrees Celsius) – while the outside of the RTG and the other side of the thermocouples are exposed to space. This outside, space-facing layer can be as cold as a few hundred degrees Fahrenheit below zero. This strong temperature difference allows an RTG to turn the heat from radioactive decay into electricity. That electricity powers all kinds of spacecraft, from communications systems to science instruments to rovers on Mars, including five current NASA missions. But don’t get too excited about buying an RTG for your house. With the current technology, they can produce only a few hundred watts of power. That may be enough to power a standard laptop, but not enough to play video games with a powerful GPU. For deep-space missions, however, those couple hundred watts are more than enough. The real benefit of RTGs is their ability to provide predictable, consistent power. The radioactive decay of plutonium is constant – every second of every day for decades. Over the course of about 90 years, only half the plutonium in an RTG will have decayed away. An RTG requires no moving parts to generate electricity, which makes them much less likely to break down or stop working. Additionally, they have an excellent safety record, and they’re designed to survive their normal use and also be safe in the event of an accident.

RTGs in action

RTGs have been key to the success of many of NASA’s solar system and deep-space missions. The Mars Curiosity and Perseverance rovers and the New Horizons spacecraft that visited Pluto in 2015 have all used RTGs. New Horizons is traveling out of the solar system, where its RTGs will provide power where solar panels could not. However, no missions capture the power of RTGs quite like the Voyager missions. NASA launched the twin spacecraft Voyager 1 and Voyager 2 in 1977 to take a tour of the outer solar system and then journey beyond it.

Each craft was equipped with three RTGs, providing a total of 470 watts of power at launch. It has been almost 50 years since the launch of the Voyager probes, and both are still active science missions, collecting and sending data back to Earth. Voyager 1 and Voyager 2 are about 15.5 billion miles and 13 billion miles (nearly 25 billion kilometers and 21 billion kilometers) from the Earth, respectively, making them the most distant human-made objects ever. Even at these extreme distances, their RTGs are still providing them consistent power. These spacecraft are a testament to the ingenuity of the engineers who first designed RTGs in the early 1960s. Benjamin Roulston, Assistant Professor of Physics, Clarkson University This article is republished from The Conversation under a Creative Commons license. Read the original article.