NASA's Expedition 19 crew captured satellite imagery of man-made object that's slowing down Earth's rotation

NASA’s Expedition 19 mission made history for multiple reasons.

Launched in 2009, the crew conducted a range of scientific experiments aboard the International Space Station, worked on complex engineering tasks, and supported Earth observation programs.

One of their most impressive observations was the capture of satellite imagery of the Three Gorges Dam in China, a human-made structure that scientists say is having an impact on the planet’s rotation.

The Three Gorges Dam spans the Yangtze River in China and is the world’s largest hydroelectric power station. While the dam is often praised for its ability to reduce flooding and generate clean energy, it has also shown how large-scale human structures can impact the Earth itself.

The Three Gorges Dam in China (Getty Stock Image/prill)

In the case of the Three Gorges Dam, NASA scientists and geophysicists have calculated that the reservoir’s 39 trillion kilograms of water, when filled to capacity, has a measurable effect on the rotation, even stretching the day by 0.06 seconds.

What started as a photograph taken from low Earth orbit has evolved into a wider conversation about how humanity is shaping the planet, not just on the surface, but in ways that affect its core behaviours.

NASA’s Expedition 19 proved that space exploration is not only about studying stars and planets far away, but also about looking a little closer to home too. It also helps us to look at out planet and get a better understanding of how our actions are changing it, allowing humanity to make any changes needed.

The photograph also helped shed light on how human-made reservoirs can cause changes beyond rotation.

The dam and river photographed from above (NASA)

The redistribution of water mass can lead to shifts in the Earth’s axis, known as polar drift. The Three Gorges Dam - which was completed in 2006 - is one of a few mega-reservoirs on the planet that could potentially contribute to this effect.

Observation teams have used such imagery to further research into how dams, groundwater depletion, and melting ice all interact with Earth’s physical balance.

The work done during Expedition 19 helped set the stage for future Earth observation missions. It confirmed the value of continuous monitoring of the planet using space stations.

As climate change and human development continue to reshape Earth, satellite imagery could be one of the most important tools for humanity to help fix the issues that they created in the first place.

While many of you may have thought that NASA's only focus was up in the stars, the space agency is looking towards home much more than you might have previously realised.