The quest to find signs of ancient life on Mars

Mars may now be considered a barren, icy desert but did Earth’s nearest neighbour once harbour life?

It is a question that has preoccupied scientists for centuries and fired up sci-fi imaginings.

Now three space exploration projects are gearing up to launch some of the most ambitious bids yet to find an answer.

Scientists believe that four billion years ago the two planets both had the potential to nurture life -- but much of Mars’ intervening history is an enigma.

The new Mars probes from the United States, United Arab Emirates and China will launch this summer.

Their goal is not to find Martian life -- scientists believe nothing would survive there now -- but to search for possible traces of past lifeforms.

These vast and costly programmes could prove futile. But astrobiologists say the red planet is still our best hope for finding a record of life on other planets.

Mars is "the only planet with concrete chances of finding traces of extraterrestrial life because we know that billions of years ago it was inhabitable," said Jean-Yves Le Gall, president of French space agency CNES in a conference call with journalists this week.

Le Gall is one of the architects of Nasa’s Mars 2020 exploratory probe, which is scheduled for launch at the end of July when Earth and Mars will be the closest for more than two years.

The more than $2.5 billion project is the latest -- and most technologically advanced -- attempt to uncover Mars’ deep buried secrets.

But it is not alone, as enthusiasm for space exploration has reignited.

Scientific enquiry of the red planet began in earnest in the 17th Century.

In 1609 Italian Galileo Galilei observed Mars with a primitive telescope and in doing so became the first person to use the new technology for astronomical purposes.

Fifty years later Dutch astronomer Christiaan Huygens used a more advanced telescope of his own design to make the first ever topographical drawing of the planet.