12.5 million tomato seeds, 69 months in space and 3.3 million students: NASA’s unusual experiment

NASA sent 12.5 million tomato seeds into space in 1984 to find out whether prolonged exposure to the space environment would affect their germination and growth, The Times of India reported on Sunday.

The seeds returned to Earth nearly six years later, in 1990, but the agency never observed them growing in space. Instead, the seeds became part of a massive classroom experiment involving about 3.3 million students.

The project, called SEEDS, or Space Exposed Experiment Developed for Students, involved NASA headquarters, the Langley Research Centre and George W. Park Seed, a traditional seed supplier in the US.

Seeds spend nearly six years in space

All 12.5 million seeds were of the Rutgers California Supreme variety, a common tomato in American cultivation. Using one variety helped prevent genetic differences from affecting the results.

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The seeds were carried aboard the Long Duration Exposure Facility (LDEF), a twelve-sided cylindrical structure weighing about 9.7 tons. It was designed to expose experiments to vacuum, radiation and micrometeorites.

The Space Shuttle Challenger released the LDEF into orbit on April 7, 1984, during the STC-41 C mission. It was supposed to be retrieved within a year, but that plan changed after Challenger exploded 73 seconds after launch on January 28, 1986, killing all seven crew members.

Without propulsion to correct its trajectory, the LDEF gradually lost altitude. Its orbit eventually dropped to about 280 kilometres, leaving it weeks away from re-entering the atmosphere when it was finally rescued.

The Space Shuttle Columbia captured the platform on January 12, 1990, during the STS-32 mission. The seeds had spent 69 months in orbit, completing more than 32,000 orbits around Earth.

Students compared space and Earth seeds

The seeds had remained sealed throughout the mission and were exposed to solar radiation, cosmic rays and microgravity.

After their return, approximately 132,000 planting kits were distributed to teachers at about 40,000 schools across all 50 US states, the District of Columbia and another 30 countries.

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Each kit contained space-exposed seeds and a control group kept on Earth. Students recorded germination, growth, flowering, fruit formation and the condition of leaves and stems. NASA received nearly 8,000 reports submitted by entire classes.

Preliminary data showed a germination rate of 73.8% for the space seeds, compared with 70.3% for the Earth seeds. The space seeds also germinated slightly faster, averaging 8 days compared with 8.3 days.

However, the project's summary found no overall differences between the two groups of plants or their fruits. The early growth advantage did not persist.

Ultimately, nearly six years in space produced no lasting differences in the tomatoes, but SEEDS became one of the largest classroom science projects involving material exposed to space.