Plants to sustain long-distance space travel
Food-producing plants will become a regular feature of long-distance space travel. They will provide nutrition, but will also scrub the air clean of carbon dioxide, deliver fresh oxygen, purified water and even deal with human waste.
Just 50 square metres of plants per person, a seven by seven-metre patch, should be enough to deliver all of these benefits, according to the head of crop research for Nasa's "advanced life support programme", Dr Raymond Wheeler.
A plant physiologist, Dr Wheeler will deliver the annual Bord Bia-sponsored David Robinson Memorial Lecture this afternoon at the Kildalton Agricultural and Horticultural College, Piltown, Co Kilkenny.
He will talk about Nasa's research into the possibility of producing fresh vegetables and small fruits in space to supplement space travellers' diets.
He will also discuss studies into how to grow wheat, potatoes, carrots and other vegetables once space travellers set up bases on the moon and Mars. "When humans venture beyond earth orbit and on to Mars, horticulture and plants will surely follow," he believes.
Much research has already been done using test systems on earth, but plants including mustard cress have also been grown successfully in space in the Russian Mir space station, he told The Irish Times.
"The cosmonauts thought it was very good. They really enjoyed fresh flavours added to their stored foods," Dr Wheeler said.
There had also been successful "seed to seed" trials in space using a variety of plants including wheat. Plants started as seeds were able to grow and produce their own viable seeds.
There were significant challenges using plants for essential life-support during long-distance flights, including getting enough light and watering plants without the help of gravity, he stated. "The problem is how do you water plants in weightlessness. This is not a trivial issue."
Experiments in space have already shown that plants grow normally without gravity, but must be given adequate light, particularly blue light, to encourage them to grow straight.
A 25sq m patch of wheat, potatoes and salad greens would be enough to clean up all the carbon dioxide given off by a single astronaut and reprocess it into oxygen, he said. It would also provide fresh produce to supplement stored foods.
A 40 to 50sq m patch could scrub the air of carbon dioxide but also produce all the food a person would need including carbohydrates, fat and protein, he stated.
Water transpired by the plants could be collected from the air to deliver purified water, and human wastes could be recycled into the plant system after primary treatment to replace water and also deliver plant nutrients. Having plants to tend on board a spacecraft may provide other hidden benefits, he added.
"There might be psychological advantages to having some plants and other living organisms around."
Plant-growing systems were being tested for eventual use on permanent bases on the moon and Mars, he said.
"In any situation the plants will need to be in a controlled structure."
Belfast-born David Robinson, in whose honour the memorial lecture is held, was a passionate horticulturist who made an important contribution to the promotion of horticulture both in Ireland and internationally.