In 2004, ESA grew rocket seeds on the ISS with André Kuipers; after four days, dark-grown seedlings were taller and yellow, while lit ones stayed smaller and green

In 2004, a simple school project flew all the way to space. Dutch astronaut André Kuipers carried rocket seeds to the International Space Station as part of Europe's DELTA mission. Simultaneously, thousands of schoolchildren grew seeds similar to those in their classrooms. This project was called “Seeds in Space” by the European Space Agency, and its purpose was pretty simple: to find out if plants grow due to light or gravity. Four days later, the results were clear.

A science project with thousands of young helpers

Kuipers took off for the International Space Station in April 2004 as a member of the DELTA mission organized by the European Space Agency. This mission mainly focused on Dutch-backed research and school projects. "Seeds in Space" turned out to be one of the most popular components of this mission. ESA reported that more than 60,000 students were involved in the program from their schools, all aged between 11 and 13 years; later ESA summaries put the figure closer to 70,000. They each planted rocket seeds at the same time as Kuipers did on the space station so that later they could compare notes with a real astronaut. It was easy to set this up from home or in classroom settings. All the "growing rocket" packages had two chambers in them. One chamber let light enter it while the other chamber was kept in darkness.


Four days later, two very different results

Four days after planting, Kuipers opened his own kit. He did this live, during a video link from the space station. While inside the ISS's normally lit interior, the darkness was contained entirely within the kit's sealed chamber, not the room around him. What he saw was chaos. The plants in the dark chamber had been growing irregularly, he observed, with the sprouts growing in different directions. The light chamber looked very different. The small plants had grown larger and greener, all tilting towards the light source. The same pattern appeared in the classrooms. In dark chambers, the plants grew taller; however, instead of being green, they turned yellow. The plants remained smaller in the light chambers. However, the plants appeared healthier and had greener colors with thicker stems. ESA summed up the lesson in simple terms: light and gravity both help a plant know which way to grow. Remove either factor or block the light, and the plant loses its sense of direction.

Why plants stretch and turn pale without light

This pattern is also seen in plant science on Earth. Seedlings that are kept away from light generally end up being taller and thinner than usual. According to a review published in 2020 titled 'Beyond the Darkness: Recent Lessons From Etiolation and De-Etiolation Studies' in the Journal of Experimental Botany, this is because seedlings without access to light consume most of their stored energy for rapid vertical growth. They try to reach out to the sunlight. As noted by this review, these seedlings also skip making the green, light-catching parts inside their cells. Instead, they build a temporary support structure. It doesn't turn green until real light finally reaches it. In general, a seedling left in the dark ends up tall and pale, whereas a light-exposed one remains shorter and greener. This same random-direction growth pattern showed up in Kuipers's dark chamber, high above Earth rather than inside a lab.

Why this still matters for space travel

Growing plants in space is no longer a school project. Crewed missions to the Moon are already underway again, and soon enough we might see trips to Mars too. These trips would last from months to possibly even years and crews will probably have to grow some of their own food, rather than relying solely on supplies from home. Since Kuipers's flight, research on light and low gravity has greatly expanded. In 2022, the study, ‘Red Light Enhances Plant Adaptation to Spaceflight and Mars g-Levels,’ published in the journal Life, looked at NASA and ESA’s subsequent Seedling Growth experiments in orbit. It showed that certain types of light can help plants adapt to stress caused by low gravity. The light also helped undo some of the odd genetic changes brought on by spaceflight. The newer study rests on the very basic concept that students saw way back in 2004. Plants require light for growth, both on the ground and in space. Light acts as a signal to the plant that helps it stop growing randomly and start developing the parts it needs to survive.

A simple box, a lesson that lasts

What began as a fun pre-teen project turned out to have real scientific weight. In two small side-by-side chambers, Kuipers showed something that now shapes real plans to feed astronauts on long space missions. Some of the clearest science lessons are from the simplest setups: a seed, a box, and the difference a little light can make.