Title: NASA Astronaut Demonstrates How to ‘Weigh’ Oneself in Space: A Busy Week Aboard the ISS
When we step on a scale on Earth, gravity pulls us down and the scale measures that force, revealing our weight. But how do astronauts aboard the International Space Station (ISS) — a zero-gravity environment — know how much they ‘weigh’? The crew of Expedition 73 offered a fascinating insight into this question during a busy week in Earth orbit between November 17-21, 2025.
The ISS, a marvel of international cooperation and human ingenuity, orbits Earth every 90 minutes. It’s home to astronauts from around the world, conducting scientific research that would be impossible anywhere else. Aboard the ISS, the Expedition 73 crew not only works on groundbreaking experiments but also navigates daily life in a setting where the conventional rules of gravity do not apply.
This week, one of the Expedition 73 astronauts demonstrated the unique method they use to measure their body mass in space. Unlike traditional scales that depend on gravity, the astronauts use a device called the Space Linear Acceleration Mass Measurement Device (SLAMMD). The principle behind this tool is Newton’s second law of motion, which states that force equals mass times acceleration.
In the absence of gravity, the SLAMMD measures an astronaut’s mass by applying a known force to their body and measuring how much they accelerate. It’s a space-age twist on the classic push-and-pull dynamic we experience on Earth, transformed into a way to ‘weigh’ astronauts in an environment where weight has no meaning.
In addition to this intriguing demonstration, the Expedition 73 crew had a bustling week. The nearly 1 million-pound orbiting complex requires constant maintenance and upgrades. Among their tasks, the astronauts installed new solar arrays, performed science experiments related to human health and climate change, and communicated with mission control for critical station operations.
The ISS is not just a space laboratory but also a home to these astronauts. Amid their rigorous work schedule, the crew also took time to share their experiences and views of Earth from 250 miles above, inspiring those of us on the ground with stunning images and a reminder of our planet’s beauty and fragility.
The activities of Expedition 73’s crew highlight the ongoing human quest for knowledge and exploration. Their work in the unique microgravity environment of the ISS continues to contribute to our understanding of space and its potential impacts and benefits for life on Earth.
As we marvel at the astronauts’ weightless existence aboard the ISS, we are reminded that the final frontier is not as distant as it seems. It’s right above us, a constant source of inspiration and a testament to our limitless potential when we reach for the stars.
Read more from the original source here: [NASA astronaut shows how to ‘weigh’ yourself in space | On the ISS this week Nov. 17-21, 2025](https://www.space.com/space-exploration/international-space-station/nasa-astronaut-shows-how-to-weigh-yourself-in-space-on-the-iss-this-week-nov-17-21-2025).