Science in Space April 2025

Humans have always been explorers, venturing by land and sea into unknown and uncharted places on Earth and, more recently, in space. Early adventurers often navigated by the Sun and stars, creating maps that made it easier for others to follow. Today, travelers on Earth have sophisticated technology to guide them.

Navigation in space, including for missions to explore the Moon and Mars, remains more of a challenge. Research on the International Space Station is helping NASA scientists improve navigation tools and processes for crewed spacecraft and remotely controlled or autonomous robots to help people boldly venture farther into space, successfully explore there, and safely return home.

A current investigation, NAVCOM, uses the space station’s ISS Ham Radio program hardware to test software for a system that could shape future lunar navigation. The technology processes signals in the same way as global navigation satellite systems such as GPS, but while those rely on constellations of satellites, the NAVCOM radio equipment receives position and time information from ground stations and reference clocks.

The old made new

Sextant Navigation tested star-sighting from space using a hand-held sextant. These mechanical devices measure the angle between two objects, typically the Sun or other stars at night and the horizon. Sextants guided navigators on Earth for centuries and NASA’s Gemini and Apollo missions demonstrated that they were useful in space as well, meaning they could provide emergency backup navigation for lunar missions. Researchers report that with minimal training and practice, crew members of different skill levels produced quality sightings through a station window and measurements improved with more use. The investigation identified several techniques for improving sightings, including refocusing between readings and adjusting the sight to the center of the window.

Navigating by neutron stars

The station’s NICER instrument studies the nature and behavior of neutron stars, the densest objects in the universe. Some neutron stars, known as pulsars, emit beams of light that appear to pulse, sweeping across the sky as the stars rotate. Some of them pulse at rates as accurate as atomic clocks. As part of the NICER investigation, the Station Explorer for X-ray Timing and Navigation Technology or SEXTANT tested technology for using pulsars in GPS-like systems to navigate anywhere in the solar system. SEXTANT successfully completed a first in-space demonstration of this technology in 2017. In 2018, researchers reported that real-time, autonomous X-ray pulsar navigation is clearly feasible and they plan further experiments to fine tune and modify the technology.

Robot navigation

Crews on future space exploration missions need efficient and safe ways to handle cargo and to move and assemble structures on the surface of the Moon or Mars. Robots are promising tools for these functions but must be able to navigate their surroundings, whether autonomously or via remote control, often in proximity with other robots and within the confines of a spacecraft. Several investigations have focused on improving navigation by robotic helpers.

The SPHERES investigation tested autonomous rendezvous and docking maneuvers with three spherical free-flying robots on the station. Researchers reported development of an approach to control how the robots navigate around obstacles and along a designated path, which could support their use in the future for satellite servicing, vehicle assembly, and spacecraft formation flying.

The station later gained three cube-shaped robots known as Astrobees. The ReSWARM experiments used them to test coordination of multiple robots with each other, cargo, and their environment. Results provide a base set of planning and control tools for robotic navigation in close proximity and outline important considerations for the design of future autonomous free-flyers.

Researchers also used the Astrobees to show that models to predict the robots’ behavior could make it possible to maneuver one or two of them for carrying cargo. This finding suggests that robots can navigate around each other to perform tasks without a human present, which would increase their usefulness on future missions.

An investigation from ESA (European Space Agency), Surface Avatar evaluated orbit-to-ground remote control of multiple robots. Crew members successfully navigated a four-legged robot, Bert, through a simulated Mars environment. Robots with legs rather than wheels could explore uneven lunar and planetary surfaces that are inaccessible to wheeled rovers. The German Aerospace Center is developing Bert.

Science in Space April 2025

Humans have always been explorers, venturing by land and sea into unknown and uncharted places on Earth and, more recently, in space. Early adventurers often navigated by the Sun and stars, creating maps that made it easier for others to follow. Today, travelers on Earth have sophisticated technology to guide them.

Navigation in space, including for missions to explore the Moon and Mars, remains more of a challenge. Research on the International Space Station is helping NASA scientists improve navigation tools and processes for crewed spacecraft and remotely controlled or autonomous robots to help people boldly venture farther into space, successfully explore there, and safely return home.

A current investigation, NAVCOM, uses the space station’s ISS Ham Radio program hardware to test software for a system that could shape future lunar navigation. The technology processes signals in the same way as global navigation satellite systems such as GPS, but while those rely on constellations of satellites, the NAVCOM radio equipment receives position and time information from ground stations and reference clocks.

The old made new

Sextant Navigation tested star-sighting from space using a hand-held sextant. These mechanical devices measure the angle between two objects, typically the Sun or other stars at night and the horizon. Sextants guided navigators on Earth for centuries and NASA’s Gemini and Apollo missions demonstrated that they were useful in space as well, meaning they could provide emergency backup navigation for lunar missions. Researchers report that with minimal training and practice, crew members of different skill levels produced quality sightings through a station window and measurements improved with more use. The investigation identified several techniques for improving sightings, including refocusing between readings and adjusting the sight to the center of the window.

Navigating by neutron stars

The station’s NICER instrument studies the nature and behavior of neutron stars, the densest objects in the universe. Some neutron stars, known as pulsars, emit beams of light that appear to pulse, sweeping across the sky as the stars rotate. Some of them pulse at rates as accurate as atomic clocks. As part of the NICER investigation, the Station Explorer for X-ray Timing and Navigation Technology or SEXTANT tested technology for using pulsars in GPS-like systems to navigate anywhere in the solar system. SEXTANT successfully completed a first in-space demonstration of this technology in 2017. In 2018, researchers reported that real-time, autonomous X-ray pulsar navigation is clearly feasible and they plan further experiments to fine tune and modify the technology.

Robot navigation

Crews on future space exploration missions need efficient and safe ways to handle cargo and to move and assemble structures on the surface of the Moon or Mars. Robots are promising tools for these functions but must be able to navigate their surroundings, whether autonomously or via remote control, often in proximity with other robots and within the confines of a spacecraft. Several investigations have focused on improving navigation by robotic helpers.

The SPHERES investigation tested autonomous rendezvous and docking maneuvers with three spherical free-flying robots on the station. Researchers reported development of an approach to control how the robots navigate around obstacles and along a designated path, which could support their use in the future for satellite servicing, vehicle assembly, and spacecraft formation flying.

The station later gained three cube-shaped robots known as Astrobees. The ReSWARM experiments used them to test coordination of multiple robots with each other, cargo, and their environment. Results provide a base set of planning and control tools for robotic navigation in close proximity and outline important considerations for the design of future autonomous free-flyers.

Researchers also used the Astrobees to show that models to predict the robots’ behavior could make it possible to maneuver one or two of them for carrying cargo. This finding suggests that robots can navigate around each other to perform tasks without a human present, which would increase their usefulness on future missions.

An investigation from ESA (European Space Agency), Surface Avatar evaluated orbit-to-ground remote control of multiple robots. Crew members successfully navigated a four-legged robot, Bert, through a simulated Mars environment. Robots with legs rather than wheels could explore uneven lunar and planetary surfaces that are inaccessible to wheeled rovers. The German Aerospace Center is developing Bert.

NASA astronaut Don Pettit is scheduled to return home in mid-April after a seven-month mission aboard the International Space Station as part of Expedition 72. Throughout his stay, Pettit contributed to research that benefits humanity and future space missions.

Pettit also shared what he calls “science of opportunity” to demonstrate how experimenting with our surroundings can help gain a better understanding of how things work. This understanding is perhaps enhanced when art, science, and microgravity come together.

Electrostatic Displays

NASA astronaut Don Pettit demonstrates electrostatic forces using charged water droplets and a knitting needle made of Teflon. This series of overlapping frames displays the unique attraction-repulsion properties of Teflon and charged droplets, similar to how charged particles from the Sun behave when they come in contact with Earth’s magnetic field. Highly energetic particles from space that collide with atoms and molecules in the atmosphere create the aurora borealis.

Specialized Equipment for Superb Science

NASA astronaut Don Pettit snaps an image of the hands of NASA astronauts Nick Hague, left, and Suni Williams inside the Life Science Glovebox, a facility at the International Space Station that separates the science from the scientists, thus protecting both from contamination.

The freezers on the International Space Station are as crucial as its experiment modules, preserving samples for further analysis on Earth. The Minus Eighty-Degree Laboratory Freezer for International Space Station stores samples at ultra-cold temperatures. NASA astronaut Don Pettit used it to freeze thin ice wafers, which he photographed with a polarizing filter to reveal unique crystal structures.

New Tech Roll-Out

NASA astronaut Don Pettit films a time-lapse sequence of Canadarm2 retrieving Materials International Space Station Experiment (MISSE-20-Commercial) samples at the International Space Station. This investigation exposed various experiments to the harsh space environment, such as vacuum, radiation, and extreme temperatures. Findings could help in many areas, from designing more durable materials to advancing quantum communications.

A surge in International Space Station research supports NASA’s exploration efforts at the Moon and beyond, requiring more energy to operate the orbiting laboratory. NASA astronaut Don Pettit photographs new and old solar arrays side by side. The technology used by the International Space Station Roll-Out Solar Arrays (IROSA) on the right was first tested aboard the station in 2017. By 2023, six IROSAs were deployed aboard station, providing a 20-30% increase in power for research and operations. Roll-Out Solar Arrays were also used on NASA’s DART asteroid mission and now are slated for the Gateway lunar outpost, a vital component of Artemis.

Squire for Spacewalks

NASA astronaut Don Pettit helped his colleagues suit up for two spacewalks in January. The first spacewalk involved patching the Neutron Star Interior Composition Explorer (NICER), a telescope that measures X-rays from neutron stars and other cosmic objects. Sunlight interference affected data collection, and the patches reduced this issue. On the second spacewalk, astronauts collected samples from the exterior of the International Space Station for ISS External Microorganisms. This investigation examines whether the orbiting laboratory releases microbes, how many, and how far these may travel. Findings could inform the design of future spacecraft, including spacesuits, to limit biocontamination during future space missions.

Photography with a Spin

NASA astronaut Don Pettit photographs “cosmic colors at sunrise.” From 250 miles above, the International Space Station’s orbital path covers most of Earth’s population, offering valuable data and a great opportunity for shooting breathtaking photography.

NASA astronaut Don Pettit leveraged his stay aboard the International Space Station to photograph our planet with an artistic twist.

NASA astronaut Don Pettit wrote on social media about his snapshot of the Mediterranean Sea from the International Space Station, “Sun glint off the Mediterranean Sea (infrared and converted to black and white). When the Sun reflects off the ocean, watery details unseen with normal lighting appear. Small centimeter differences in ocean height become visible, revealing hidden currents.”

NASA astronaut Don Pettit’s photography could contribute to the study of transient luminous events, colorful electrical discharges that occur above thunderstorms. His imagery can be paired with data from the Atmosphere-Space Interactions Monitor (ASIM) and Thor-Davis, a high-speed thunderstorm camera. The combined efforts of crew photography and instruments aboard the International Space Station help scientists better understand thunderstorms and their impacts on Earth’s upper atmosphere.

More of Pettit’s photography can be found on his X profile, @astro_Pettit.

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Science in Space: February 2025

February was first proclaimed as American Heart Month in 1964. Since then, its 28 (or 29) days have served as an opportunity to encourage people to focus on their cardiovascular health.

The International Space Station serves as a platform for a variety of ongoing research on human health, including how different body systems adapt to weightlessness. This research includes assessing cardiovascular health in astronauts during and after spaceflight and other studies using models of the cardiovascular system, such as tissue cultures. The goal of this work is to help promote heart health for humans in space and everyone on Earth. For this Heart Month, here is a look at some of this spaceflight research

Building a better heart model

Microgravity exposure is known to cause changes in cardiovascular function. Engineered Heart Tissues assessed these changes using 3D cultured cardiac tissues that model the behavior of actual heart tissues better than traditional cell cultures. When exposed to weightlessness, these “heart-on-a-chip” cells behaved in a manner similar to aging on Earth. This finding suggests that these engineered tissues can be used to investigate the effects of space radiation and long-duration spaceflight on cardiac function. Engineered tissues also could support development of measures to help protect crew members during a mission to Mars. Advanced 3D culture methodology may inform development of strategies to prevent and treat cardiac diseases on Earth as well.

Private astronaut heart health

For decades, human research in space has focused on professional and government-agency astronauts, but commercial spaceflight opportunities now allow more people to participate in microgravity research. Cardioprotection Ax-1 analyzed cardiovascular and general health in private astronauts on the 17-day Axiom-1 mission.

The study found that 14 health biomarkers related to cardiac, liver, and kidney health remained within normal ranges during the mission, suggesting that spaceflight did not significantly affect the health of the astronaut subjects. This study paves the way for monitoring and studying the effects of spaceflight on private astronauts and developing health management plans for commercial space providers.

Better measurements for better health

Vascular Echo, an investigation from CSA (Canadian Space Agency), examined blood vessels and the heart using a variety of tools, including ultrasound. A published study suggests that 3D imaging technology might better measure cardiac and vascular anatomy than the 2D system routinely used on the space station. The research team also developed a probe for the ultrasound device that better directs the beam, making it possible for someone who is not an expert in sonography to take precise measurements. This technology could help astronauts monitor heart health and treat cardiovascular issues on a long-duration mission to the Moon or Mars. The technology also could help patients on Earth who live in remote locations, where an ultrasound operator may not always be available.

Long-term heart health in space

As part of exploring ways to keep astronauts healthy on missions to the Moon and Mars, NASA is conducting a suite of space station studies called CIPHER that looks at the effects of spaceflight lasting up to a year. One CIPHER study, Vascular Calcium, examines whether calcium lost from bone during spaceflight might deposit in the arteries, increasing vessel stiffness and contributing to increased risk of future cardiovascular disease. Astronaut volunteers provide blood and urine samples and undergo ultrasound and high-resolution scans of their bones and arteries for this investigation. Another CIPHER study, Coronary Responses, uses advanced imaging tests to measure heart and artery response to spaceflight.

These studies will help scientists determine whether spaceflight accelerates narrowing and stiffening of the arteries, known as atherosclerosis, or increases the risk of atrial fibrillation, a rapid and irregular heartbeat seen in middle-aged adults. This work also could help identify potential biomarkers and early warning indicators of cardiovascular disease.

Melissa Gaskill

International Space Station Research Communications Team

Johnson Space Center