Perhaps thanks to the popularity of science fiction writer H.G. Wells' The War of the Worlds in 1897, some people had imagined technologically advanced Martians invading Earth. In reality, any 'Martians' we can expect to find would be microbes or their chemical signatures, at the lower end of the evolutionary tree.

In 1965, high resolution pictures taken by Nasa's Mariner 4 probe showed a dry Mars without rivers, oceans or any signs of water deposits. Scientists also argued that strong ultraviolet radiation due to extreme thin atmosphere would have killed all organic molecules on the surface.

However, more recent studies have found that so-called 'extremophiles', usually organisms, actually thrive in extreme condition. These creatures live in underwater volcanoes at boiling-point temperature.

In 1976, the US Viking Landers were tasked to explore the possibility of life on Mars, but territorial samples they collected led Nasa to conclude that the evidence was not sufficient to conclude for or against (past) life forms.

It has been argued that gradual thinning of the atmosphere - to 0.7 per cent of Earth's several billion years ago - would have caused any liquid water, the essence of life, to disappear due to sublimation. This does not exclude the possibility of micro-organisms that may still lie deep under the planet's surface where all the water escaped.

The discovery suspected micro-organelle in a Martian rock labelled ALH84001 found in the Antarctic at the end of the last century was a boost for space agencies interested in returning to Mars.

I was thinking about these questions when I decided to approach the European Space Agency, which, in the late 1990s, was actively planning its first exobiological mission to Mars.

Scientists realised that in 2003 both planets were in closest opposition, or perihelion in centuries, cutting travel time to little more than five months.

Both the Americans and the Europeans wanted to launch missions to take advantage of the closing distance to save fuel that could carry extra payload. The mission of the European Space Agency is called Mars Express. Europeans had come rather late in the exploration of the planet.

Recent and ongoing American missions have not focused on finding life forms on Mars but on a different, albeit crucially related issue: liquid water.

It is generally accepted that Mars once had lakes, rivers or oceans before its atmosphere disappeared.

I wasn't just interested in water, life's source; I wanted to know about life itself. I wanted to be a part of a mission to explore Mars' soil to look for (past) signs of life.

Even before the Europeans accepted the Hong Kong contribution, I was already conceptualising territorial sampling tools that would be needed for an exobiological mission.

They would need to move a laboratory, entirely automated, to Mars, to analyse the chemical composition of samples retrieved inside the rocks or under soil.

We would invent a new design concept called a 'holinser' for exobiological missions - precision forceps that could function as a drill and be able to extract fine powdered samples. The device would be attached to the end of a robotic arm on board a space lander.

I realised that with our new concept in planetary micro-sampling, we could approach ESA space scientists to offer our service.

My work with the Russian Mir space station had helped open doors. Our work in Hong Kong was beginning to bear fruit. My 'super-chopsticks' - the holinser - would be my ticket to Mars.

Next week: Working for the European Space Agency