NASA is experimenting with growing fresh vegetables aboard the International Space Station, or ISS, using what the space agency calls plant pillows -- NASAs version of an ordinary grow bag commonly preferred by tomato farmers. The goal is to establish a garden aboard the station that would give astronauts a chance to pick their own meals.

NASA announced the fresh food program last month shortly before SpaceX made a delivery to the ISS of 2.5 tons of cargo early Easter morning.

The April payload included a portable pop-up greenhouse for growing things like lettuce. The space agencys garden program is appropriately nicknamed Veggie.

With the plant pillows successfully delivered, astronomers are one step closer to enjoying the first fresh salad in space.

"The ability to grow food in space will become increasingly important in the context of future long-duration space missions, and especially in the context of future human settlements on the moon and Mars," Ian Crawford, a professor ofplanetary science and astrobiology at Birkbeck, University of London, told the Guardian. "These experiments are an important step in developing this capability."

Growing plants in space has its own unique set of challenges. In zero gravity conditions, seeds dont remain in the soil, and water pools around the roots which can choke the plants.

Plants in space also have a hard time knowing which way is up and which way is down, meaning they often wont sprout in the appropriate direction.

NASAs plant pillows include a base with a reservoir of water that is covered with a permeable fabric. A series of wicks guide the water towards the plants as the water seeps into the soil. The wicks also help to keep the plants growing upright.

The seeds themselves are glued in the correct orientation. A set of LED lights provides the plants with energy.

Two of the NASA plant pillows contain seeds of red romaine lettuce. The third holds zinnia seeds, a flowering plant.

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NASA Plant Pillows Give Astronauts On The International Space Station A Chance To Grow Their Own Veggies