What do Canada and Mars have in common? The short answer is the huge area that exists above the tree line and is commonly known as the Arctic.
While historically the Arctic has been of crucial interest to explorers looking for a Northwest Passage and to anthropologists studying the ability of the Inuit to survive in one of the world's least hospitable terrains, in the past decade or so it has also experienced intense scientific scrutiny as a model for a place even more difficult to live in - Mars.
The Arctic site that has received the most media attention is the Nasa-funded "Mars analogue" on Devon Island. The site has served as a testing ground for rovers, crawling robots and other bits of technology that might eventually be used on Mars.
But the centre of true Mars-analogue Earth and biological science is the 44-year-old research laboratory run by McGill University on Axel Heiberg Island, in the Arctic Ocean. Since 1996, working in conjunction with Nasa, astrobiologist Chris McKay and physical geography associate professor Wayne Pollard and his students have explored a number of strange and literally far-out questions.
Could it be that the briny springs that flow all year through 600m of permafrost on Axel Heiberg are an Earth analogue for the relationship between flowing water and a frigid Mars? The answer seems to be "yes". Now the investigation has moved to a new stage. Since the uniquely salty springs of water - five to ten times saltier than the ocean - contain iron-oxidising bacteria, does that suggest that life could have hidden in something like a Martian version of the Axel Heiberg spring? Scientists also speculate that if the bacteria are no longer present, could a Martian bacterial fossil treasure-trove be awaiting investigation in the carbonate mineral deposits the water leaves behind when it flows out of the springs, freezes and evaporates? The McGill research into the Canadian Arctic's effectiveness as a model suggests that it could.
The research team is also studying the ability of Arctic bacteria to remain viable in ice for millions of years to see if that might suggest a similar icy hiding place for bacteria on Mars.
And, as is often the case here, geography and biology may be speaking with one voice. In terms of pure physical geography, the McGill group has been exploring whether understanding the nature of the permafrost in the Canadian Arctic might more clearly answer the question of whether permafrost on Mars is a haven for once-flowing water. A recent comparison of satellite data of Mars permafrost, with the geology and geography of Axel Heiberg, suggests that may well be the case. A series of papers in the past several years has tied the water flow-creating gully patterns on generally frozen Axel Heiberg with gullies that have been seen on Mars.
"What's interesting is that there is some recent evidence that some of the Martian gullies are only a couple of million years old and thus date back to a time when Mars might have been a great deal more hospitable for life," Pollard says.