The plants are monitored and tended remotely for almost the entire year. (Mars Institute)Astronauts visiting Mars in the future may be able to look forward to a fresh salad when they arrive, thanks to Canadian research.

Lettuce, radishes and beets have been planted in a remote Arctic greenhouse, where researchers are learning how to grow crops without human contact in an environment that can't normally support edible plants.

Alain Berinstain, the Canadian Space Agency scientist in charge of the project, said no other greenhouse is designed to operate autonomously like the Arthur Clarke Mars Greenhouse on Devon Island in Nunavut.

"Every greenhouse needs … electrical power, it needs heat and it needs people, to some extent," said Berinstain, director of science and academic development at the space agency. "The way we provide the people is through a remote link."

On the flip side, humans will need greenhouse-grown plants to provide food and clean the air and water if they begin to spend a lot of time on another planet or the moon, Berinstain said.

Researchers visit every summer to set up a fall crop and a spring crop and upgrade the computer hardware and software. This year, Matt Bamsey of the Canadian Space Agency, Thomas Graham of the University of Guelph and Talal Abboud of the Canadian Space Agency, left to right, did the work. (Mars Institute)The greenhouse is at the Mars Institute's Haughton-Mars Project research station, which is staffed for just a few weeks each summer. The surrounding environment is a polar desert where temperatures can dip below freezing even in July and there is little annual precipitation.

"There's very little vegetation, [it's] very rocky," Berinstain said. "It's beautifully desolate."

The harsh conditions and rocky, Mars-like landscape make it a popular spot to test robots, space suits and other technology designed for use on other planets.

"Wherever we end up operating greenhouses on other planets, it will be an extreme environment," Berinstain said. "So it's about learning to work with a greenhouse that way."

The project was established in 2002 after the Canadian Space Agency heard the Mars Institute was interested in having a greenhouse at the research station.

The researchers visit every summer to set up a spring crop and a fall crop. They also upgrade the computer systems that let them monitor the plants and keep them watered and warm during the growing seasons.

The greenhouse is heated with propane during the summer, and the computers run on solar power. Water comes from a nearby stream and some of it is saved over the winter. The plants are monitored with webcams and sensors that detect the acidity of the nutrient solution, the water levels and the temperature.

When fall arrives, the propane runs out, the plants freeze and the computers are kept running with wind power during the 24-hour darkness of the Arctic winter.

6 years of effort

In spring, temperature sensors detect when it is warm enough to start a second crop.

The computer systems run on solar power in the summer and wind power in the winter. (Mars Institute)"It took us about six years of trying before we could have a system robust enough to even work in spring," Berinstain said, adding that electronics are not designed to survive the extreme cold of the Arctic winter.

"Just being able to send commands and being able to gather data in the spring was a big milestone."

For the past three or four years, the researchers have been collaborating with scientists at the University of Florida to develop a new type of "living sensors" that can detect greenhouse conditions.

They are in the form of plants from the mustard family, called arabidopsis. Researchers have genetically engineered arabidopsis plants to glow in the dark when they're stressed — too hot, too cold, or short of water or nutrients.

"With this technique, you can ask a plant directly, 'Are you hungry, are you thirsty, are you hot, are you cold?" Berinstain said.

That means people would no longer have to guess the plant's condition, based on the sensors.

Berinstain said such living sensors would be very robust and could be used in greenhouses both in space and on Earth.