Space exploration may seem glamorous, but it’s no picnic for the astronauts who sign up to work aboard the International Space Station. While space food has come a long way since the freeze-dried ice cream and Tang you remember from childhood, the vacuum of space isn’t exactly an ideal environment for growing fresh food. That’s about to change today, though, as the astronauts aboard the ISS are set to sample some of the red romaine lettuce they’ve spent the last month growing.

“There is evidence that supports fresh foods, such as tomatoes, blueberries and red lettuce are a good source of antioxidants. Having fresh food like these available in space could have a positive impact on people’s moods and also could provide some protection against radiation in space,” said Dr. Ray Wheeler, lead for Advanced Life Support activities in the Exploration Research and Technology Programs Office at Kennedy Space Center.

With NASA’s push to send people to Mars at some point in the future, sustained food growth is a must. Named Veggie, the ISS’ plant growth program begins with rooting “pillows,” small bundles that contain the plant seeds. NASA has been testing the Veggie system since last year, when the first plants were planted in May and harvested 33 days later. However, until now the astronauts have simply frozen the plants and returned them to Earth rather than consume them.

Part of the problem with growing plants in space is light. That is, there isn’t much of it coming from the Sun, and there’s no atmosphere to speak of to capture it. To mitigate that, Veggie started with red and blue LED lights, which are efficient in giving plants the energy they need. Red and blue lights alone lead to some gross-looking plants, however, so green LEDs were included to help with that.

“Blue and red wavelengths are the minimum needed to get good plant growth,” Wheeler said. “They are probably the most efficient in terms of electrical power conversion. The green LEDs help to enhance the human visual perception of the plants, but they don’t put out as much light as the reds and blues.”

The astronauts will sample the red romaine lettuce after wiping the leaves down with citric acid-based sanitizing wipes. They’ll eat half of the harvest, then send the rest back to NASA for further testing.