Red romaine lettuce
For the first time Nasa carried out a lettuce growing experiment dubbed Veg-033 to aid astronauts on long manned missions with freshly produced food.Reuters

NASA researchers have succeeded in planting lettuce on the International Space Station (ISS) with an aim to aid long-term future manned missions to Mars.

"Just as farmers on Earth are planting leafy greens for the fall growing season, astronauts aboard the International Space Station are planting their third on-orbit crop of red romaine lettuce," NASA said in a press release.

This lettuce growing experiment, called Veg-03, has been initiated by NASA astronaut Shane Kimbrough. It is one of the first assignments that he is working on as a new orbiting lab member.

According to NASA, this study will lead to the confirmation of compulsory procedures and tools required for production of fresh food for astronauts on long-duration space missions.

"Operations went great today! A little slower than expected, but all plant pillows were successfully primed for the first time in our Veg series," stated Nicole Dufour, NASA's Veggie project manager.

NASA astronauts are given plant pillows in order to grow their own freshly produced veggies. These plant pillows comprise of fertiliser and seeds along with a growth medium and just require some amount of water.

"We previously have had some hardware issues that prevented at least one pillow from each 'grow out' from being successfully primed, so we were very excited to achieve that milestone," Dufour said in the press release.

Successful experiments have also been conducted previously, like Veg-01, which was the first on-orbit harvest sampling of fresh produce carried out in 2015.

NASA's Veggie team aims at carrying out a repetitive crop harvest technique they termed 'Cut-and-Come-Again'. This would be the Veggie team's first on-orbit mission and the technique would be very beneficial for the astronauts going on Mars missions for a long term.

"Once the plants are approximately four weeks old, a selection of leaves can be harvested for a bit of fresh lettuce and possibly science samples. Meanwhile, some leaves are left intact along with the core of the plant, and will continue to grow and produce more leaves," said Dufour.

"We expect this will increase the on-orbit crop yield, as well as allow for more opportunities to supplement our astronauts' diets with fresh, nutritious food from the same plants, which is an important goal of the 'pick-and-eat' food concept," she added.