German physicist Wilhelm Conrad Roentgen discovered on Nov. 8, 1895, during a vacuum tube experiment, that an invisible, unknown ray could penetrate objects. It was the X-ray. On Dec. 22 that year, Roentgen photographed his wife's hand with X-rays. The image, which clearly showed the outline of the bones with a wedding ring on the fourth finger, marked the start of the X-ray diagnosis era.
Roentgen received the first Nobel Prize in physics in 1901 for first discovering X-rays in 1895. One hundred thirty years after the discovery of X-rays, they have reached space. Sheyna Gifford, head of aerospace medicine research at the U.S. Mayo Clinic, said on the 14th (local time) in Radiology, the international journal of the Radiological Society of North America (RSNA), that "last year, crew members aboard a commercial spacecraft succeeded for the first time in taking X-rays in space at a level suitable for medical diagnosis."
◇ Civilian astronauts take images during polar orbit flight
U.S. space corporations SpaceX began the Fram2 spaceflight mission on Mar. 31, 2025, carrying four civilians aboard the crewed Dragon capsule. The spacecraft, commanded by Chun Wang, founder of a bitcoin mining company, launched that day atop a Falcon 9 rocket from Kennedy Space Center in Florida.
The three-and-a-half-day Fram2 mission not only set a record as the first in human history to traverse Earth's North and South Poles, but also achieved significant results in aerospace medicine. The Fram-2 astronauts used a portable X-ray device in a polar orbit 425–450 kilometers above Earth to image various parts of the body, including the hands and forearms, abdomen, pelvis, and chest.
Three radiologists evaluated the image quality, spatial resolution, contrast resolution, and positional accuracy of X-rays taken before launch, in space, and after launch. In the paper, Gifford's team noted, "There were some differences in position measurements, but images were identical on all other metrics, and those taken in flight reached diagnostic quality."
The Fram2 mission examined whether astronauts could use a commercial portable X-ray system from MinXray in the United States. Three astronauts received four hours of hands-on training and took X-rays on the ground before launch. They imaged in the same way in space. After returning to Earth, others imaged the astronauts with the same X-ray equipment.
◇ Overcoming ultrasound limits, detecting equipment failures
Since humans ventured into space, astronauts have relied only on ultrasound diagnostics. But ultrasound requires substantial training. There is also the limitation that, for an ultrasound device to work properly, the injury or disease of interest must be in a medium that responds to sound waves.
Muscles, organs, and arteries transmit sound waves well because of their high water content, but bones do not, resulting in lower resolution. Skilled clinicians know the optimal angles that allow small amounts of sound to penetrate bone, but in space, where emergencies are common, relying solely on ultrasound has been cited as a limitation of space medicine.
Gifford said, "Securing two or more imaging modalities to diagnose illness and injury in space has long been a dream in aerospace medicine," adding, "X-rays are among the most powerful diagnostic tools in modern medicine because they are fast and accurate and can be operated by anyone without a sound-transmitting medium."
Gifford tested a portable X-ray device during parabolic flights in 2022. When an aircraft free-falls from high altitude, it can simulate the microgravity of space. Gifford demonstrated that flight crew could take X-rays in a microgravity environment similar to space. The same results were achieved this time in actual space.
X-rays can also diagnose problems with space equipment. Gifford said, "You can tell whether there is a hole in a spacesuit glove, whether a rock-sampling drill has developed an internal crack and is on the verge of breaking, and whether a rock picked up while walking on the lunar surface contains the needed minerals."
Last year, astronauts scanned not only body parts but also a smartwatch with a portable X-ray device, testing the ability to diagnose not only injuries but also problems with electronics and equipment. The X-ray scan resolution of the smartwatch was on the micrometer (μm; 1 μm = one-millionth of a meter) scale.
References
Radiology (2026), DOI: https://doi.org/10.1148/radiol.260258
Radiology (2026), DOI: https://doi.org/10.1148/radiol.261976