If you were in a classroom in the early 1990s, there is a real chance you planted a piece of space history without even realizing it. NASA sent Rutgers tomato seeds into space for nearly six years and then gave them to 3.3 million students across the country, according to NASA's Technical Reports Server. Years before people started talking about growing food on Mars, this quiet classroom project was already testing whether seeds could survive years of space radiation and still grow.Why NASA left seeds in orbit for six yearsThe seeds were never meant to stay in space that long. The project, called the Space Exposed Experiment Developed for Students, or SEEDS, was a collaboration between NASA Headquarters, NASA's Langley Research Center, and the George W. Park Seed Company. Rutgers tomato seeds were loaded onto the Long Duration Exposure Facility, a satellite designed to see how materials and biological samples perform over periods in orbit. The Challenger disaster in January 1986 changed the timeline, grounding the shuttle program for about 32 months until it returned to flight in September 1988. The satellite stayed in space far longer than expected. When it finally returned to Earth in January 1990, the tomato seeds had been in orbit for nearly six years. They had been exposed to radiation and solar wind the entire time.What happened when the seeds came back to EarthWhen NASA retrieved the seeds, scientists needed a method to examine how the radiation had changed them. NASA sent 132,000 seed kits to schools across the country, reaching 3.3 million students from kindergarten to university. Each kit contained space-exposed seeds and a control batch that spent the same time in a climate-controlled warehouse on Earth. Students planted both sets, watched the seeds sprout, and mailed their observations back to NASA for analysis. This was not a controlled lab experiment. It was a classroom experiment chiefly carried out by students.NASA's LDEF being retrieved after nearly six years in orbit. Image Credit: NASAThe numbers behind the space seedsNASA's preliminary data was specific. Space seeds germinated at a rate of 73.8 percent compared with 70.3 percent for Earth-based seeds. Germination speed followed a pattern. In tests conducted within the first six months after the seeds' retrieval, space seeds took an average of eight days to germinate once planted, while Earth-based seeds averaged 8.3 days. Researchers who examined the seeds under an electron microscope explained the difference. According to a NASA-funded university analysis, the outer layer of space seeds appeared more porous than the outer layer of Earth-based seeds. That extra porosity may have allowed space seeds to absorb nutrients and moisture more readily once planted, which could explain the faster and slightly higher germination rates. To be precise, this was not proof that space travel improves seeds. NASA's own reporting called the findings preliminary. Researchers noted the number of unusual mutations across the seed population was low. The takeaway was less that the seeds improved and more that they proved tougher than expected.A bigger experiment than just tomatoesSEEDS wasn't limited to a tray of tomato seeds. According to a NASA technical report, around two million seeds, representing 120 different plant varieties across 106 species and 55 plant families, flew aboard the same facility. Those seeds were stored in a sealed canister and two smaller vented canisters, and researchers found that seeds in the sealed canister survived space exposure better than seeds stored at the seed company's facility. That detail matters for anyone planning long‑duration space missions. If future crews or automated systems ever need to carry seed stock for years at a time, how that seed stock is contained appears to matter as much as how long it spends in orbit.Why this experiment still holds upIn a project that was mainly carried out in classrooms in the 1980s and early 1990s, SEEDS produced results that still stand today. It supplied NASA with information about how living things withstand years of cosmic radiation, and it gave American students a hands-on role in space research that most of them would otherwise only read about. When anyone mentions growing food in space, this experiment remains a useful reference point for space agriculture. NASA researchers said the tomato seeds spent nearly six years orbiting Earth, returned to Earth, and sprouted at least as reliably as seeds that never left the ground.