Astronauts at the International Space Station (ISS) are all set to have a very special meal tomorrow. The meal comprising red romaine lettuce is very special as it will mark the first time when astronauts eat food that was grown on the ISS.

The ISS has a greenhouse called Lada since 2002; it has been used for studying plant growth in microgravity. Despite using the greenhouse at the ISS for many years, astronauts there haven't eaten their science experiments.

NASA said the romaine was planted by Scott Kelly, an American astronaut, engineer and a retired U. S. Navy Captain, on July 8. After consistent watering, the plants were harvested 33 days later. However, it's not as simple as it may sound. Astronauts used a plant growth system called Veggie to grow the plants.

Pre-made seed pillows were blasted with lights from red and blue LEDs. This helped them grow and successfully produce plants in 2014. However, they were sent back to earth for testing.

NASA has now given a green signal for astronauts at the ISS to consume the romaine, but they must give the leaves a wipe down with food sanitizing wipes before eating them.

Astronauts at the ISS will also send half of the haul to earth to help researchers on earth conduct further studies. Space gardens can play a key role in ensuring good health of astronauts at the ISS. Experts say fresh fruits and vegetables could be very beneficial for mental health of astronauts.