Few events since the Apollo moonshots have ignited so much interest as Nasa’s announcement confirming the discovery of liquid water still flowing on Mars. “We now know Mars was once a planet very much like Earth with warm salty seas and fresh water lakes,” Jim Green, Nasa’s planetary science director, announced on Monday.
This is a throwback to more than a century and a quarter ago when Italian astronomer, Giovanni Schiaparelli, electrified the world by claiming that he spotted “canali” (Italian for channels) on the Red Planet. At that time, excitement over the Suez Canal prompted a mistranslation of ‘canali’ to ‘canals’, fuelling speculation that intelligent life forms had built a system of canals on Mars. It even inspired HG Wells to write The War of the Worlds, in 1898, and visions of ‘little green men’ began stalking the earth.
Solid science, however, backs the latest findings. Nasa’s Mars Reconnaissance Orbiter identified waterlogged salt molecules in the long ‘streaks’ seen flowing downhill on Mars. Earlier, it was a puzzle why these streaks materialised when it is warmer and faded when it is cooler. “Something is hydrating these salts, and it appears to be these streaks that come and go with the seasons,” said Lujendra Ojha, who first proposed the theory that Mars may have liquid salt water flowing through it during summers.
Although the first spacecraft arriving on Mars in the late 1960s and early 1970s found indications of flowing water on the surface — canyons, dried river beds, and lakes — scientists had to wait till 2001 for images from Nasa’s Mars Global Surveyor to detect proof. Even after that scientists believed Mars was too cold to have liquid water — till last April, when Nasa’s Curiosity rover found out that the soil on Mars was damp with liquid brine. Brine lowers the freezing point of water and this explains the salty streams on Mars.
This is in addition to the enormous quantities of ice that lie beneath Mars’ poles. Heat a bucketful of soil from these regions, and you get more than half a bucket of liquid water. This buried frozen water probably accumulated in winter and sublimed in summer (ice doesn’t melt into liquid water on Mars; instead it sublimes, or changes directly from solid to the gaseous state — much like ‘dry ice’ does on Earth).
The presence of so much water (enough to deluge the planet if melted) opens the door to an invaluable resource for manned Mars missions: From serving as a source of fuel, drinking water, and oxygen, to the landscaping of the Martian surface for human settlement someday.
The latest findings make it reasonable to assume that some form of life could have sprung up on Mars. Meteorites from Mars landing on Earth always hinted at this possibility. If scientists re-examine the tell-tale hydrocarbon molecules they found on a meteorite that fell in the icy Allan Hills of Antarctica in 1984, whose Martian origins have been proven, we may be in for more dramatic discoveries.
If flowing water carved the vast canyons that characterise a good percentage of the ragged Martian surface, many Martian craters seem to have been produced by impacting bodies originating from the nearby asteroid belt. So it is quite possible that the hydrocarbons in the Allan Hills meteorite reached Mars from elsewhere. In other words, the microfossils within the Allan Hills could be signatures of alien life forms beyond Mars — somewhere out in the far reaches of interstellar space.
Prakash Chandra is a science writer. The views expressed are personal.