Agnirva Space Premier League - Expedition #30963: Falling Grains and Zero Gravity: The Hourglass Experiment on the ISS
- Agnirva.com
- Aug 1, 2025
- 2 min read
We’ve all watched sand trickle through an hourglass here on Earth, but what happens to those falling grains when gravity is removed from the equation? That’s the intriguing question behind the Hourglass experiment led by Masatsugu Otsuki from JAXA’s Institute of Space and Astronautical Science.
This physical science study aimed to investigate how granular materials—like sand, dust, or grains—behave in microgravity. On Earth, these materials flow and settle due to gravity. But in space, where gravity is practically nonexistent, their behavior becomes unpredictable and fascinating.
Understanding granular physics in microgravity has important applications. For instance, planetary surfaces such as those on the Moon, Mars, or asteroids are covered with regolith, which is essentially space dust. Learning how this dust moves and settles can help engineers design better landers, rovers, and excavation tools for planetary exploration.
During the experiment aboard the ISS, researchers observed how grains of different sizes and densities moved through a transparent hourglass-like apparatus. They measured flow rates, clogging behavior, and particle collisions in the absence of gravity.
The Hourglass experiment also contributed to broader physics knowledge. Granular materials don’t always behave like liquids or solids—they form their own complex state of matter. Studying them in microgravity reveals fundamental principles that can’t be seen on Earth due to gravity’s overwhelming influence.
Applications go beyond planetary science. Industries such as pharmaceuticals, agriculture, and mining can benefit from insights into how powders and grains behave under different forces. Whether it's mixing medicine or refining ores, better understanding of granular flow can lead to more efficient technologies.
The Hourglass experiment is a perfect example of how simple questions—like how grains fall—can lead to profound discoveries when asked in the context of space.
