From June 26 to July 4, 2025, the International Space Station (ISS) crew experienced a week filled with science, maintenance, and a spectacular view of Transient Luminous Events (TLEs)—rare electrical bursts above thunderstorms, seen from orbit.
A Stunning Sight from Orbit
On July 3, NASA astronaut Nichole Ayers captured a rare phenomenon while passing over Mexico and the U.S. She spotted a sprite, a type of TLE, flashing high above the clouds. Ayers shared the image on social media, writing, “Just. Wow.”
Sprites are bright, reddish bursts caused by intense lightning activity. They occur in the upper atmosphere and are often invisible from the ground. The ISS, hovering above the storms, offers an ideal vantage point to observe these mysterious flashes.
“These photos help scientists better understand the formation and characteristics of TLEs,” Ayers added.
Read: SpaceX Megarocket Explodes During Test at Starbase
Science in Motion
The crew of Expedition 73 conducted several scientific experiments throughout the week:
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Earthshine Study: NASA astronaut Jonny Kim used a camera to capture the Moon during a specific phase. This effort helps scientists study how Earth’s reflected light—Earthshine—interacts with the Moon, offering insights into climate and atmospheric conditions affecting the planet’s albedo.
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Muscle Stimulation Test: Astronaut Nichole Ayers experimented with electrical muscle stimulation during workouts. This new method aims to reduce the risk of muscle loss in microgravity. Fellow astronaut Anne McClain assisted with the tests, ensuring accurate data collection.
Daily Life on the ISS
Beyond science, the astronauts handled maintenance tasks, including preparing for incoming cargo. They also hosted researchers from the Axiom Mission 4 team, continuing international collaboration in orbit.
“Life on the ISS is a blend of routine and wonder,” noted one flight engineer. With events like sprite sightings and ongoing experiments, Expedition 73 continues to deepen human understanding of space and Earth alike.
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