How River Torrens duckweed could help mankind reach Mars

Scientists think a humble plant growing by the Torrens could help send humans to Mars and even relieve the pressure on the earth.

A humble weed that grows in the River Torrens could help send humans to Mars thanks to the work of Adelaide scientists.

Duckweed, a bright green aquatic plant that grows rapidly and is packed with nutrients, might be the key to producing food for astronauts undertaking long journeys in space according to Associate Professor Jenny Mortimer.

And Prof Mortimer said that while space horticulture was an exciting new frontier there were also many lessons to be learned about efficiently feeding a growing population right here on earth.

Prof Mortimer, who works on the project at the University of Adelaide’s Waite campus with Professor Matt Gilliham, said it was virtually impossible to take enough food on a spacecraft to undertake a multi-month journey such as the one needed to get to Mars and back.

“Most of our space travel has actually been very close to the earth,” Prof Mortimer said.

“The International Space Station is amazing, but it’s only 400km above the surface. If things go wrong you can get stuff up there in less than a day. You could be in Antarctica and be more remote than the ISS astronauts are.”

She said the idea of lunar habitation and, eventually, Martian habitation posed some unique food challenges.

“We’ve been really great at working out the physics, but we are a bit behind on the biology that goes with it,” Prof Mortimer said.

“Humans are the weakest link at this point. There’s the isolation part and the psychological component of that – humans have never been this far from the earth – and then there’s the food part.”

Adelaide scientist Associate Professor Jenny Mortimer with samples of locally found duckweed which she is studying to turn into food for the future. Picture: Naomi Jellicoe

Prof Mortimer said that with a trip to Mars taking the best part of three years, with nine months travel each way and time on the surface, a team of four astronauts would require around ten tonnes of food.

“You can’t take that with you because you don’t have space and each kilo you take with you to space costs around $20,000,” she said.

“The current plan is that you could fly things in advance and drop it off at supply points. The problem with that is that food would have to be extraordinarily stable, it would have to be radiation-proof, and that constant eating of ration-pack style food is miserable. Astronauts can go through something called menu fatigue, which is often seen in the military. Even though their rations are nutritious they’ll actually lose weight because they just stop eating.”

Enter duckweed, a plant Prof Mortimer thinks could be farmed on-board spacecraft – and perhaps even underground on Mars – as a nutritious source of food that could be grown vertically using LED lighting.

“Duckweed is actually related to plants like wheat and barley,” she said.

“It was at one time a land plant and it returned to the water. What’s really fascinating about it is that it divides more like a microbe than a plant – it splits and doubles. That means it grows really fast. It has really good protein levels and a good balance of fatty acids and starch, so it has a good nutrient status. So now it’s more about domesticating it, understanding it and choosing the winning strains.”

Prof Mortimer said that a future component of the project would involve food scientists working out ways to make the duckweed palatable.

“Perhaps they can make something that tastes like cheese or yoghurt, but that’s a research project for the next five to seven years,” she said.