Mars has significant resources to support travel to the Red Planet, Nasa scientists said at a news conference to discuss new evidence that briny water may flow on its surface.

"These observations from Mars Reconnaissance Orbiter are giving us a much better view that Mars has resources that are useful to future travellers. When you have water, what is water –hydrogen and oxygen – that's what you make rocket fuel out of," John Grunsfeld, Nasa's associate administrator for the Science Mission Directorate said.

He also noted Mars' abundance of perchlorate , a type of salt typically used as a propellant. "Solid rocket boosters are aluminum perchlorate. In principal, you can make solid rocket fuel," Grunsfeld said.

The finding that water may flow on Mars could affect thinking about whether the Red Planet can support present-day microbial life. Scientists said it has also raised concerns that exploration efforts on Mars could inadvertently contaminate the planet, an issue scientists refer to as "planetary protection". Grunsfeld also said Nasa has likewise taken efforts to ensure that rovers used on Mars are thoroughly cleaned in order to prevent introducing new bacteria from being brought to Earth.

"It's not only protecting us from bringing some alien lifeform to Earth but more so right now, it's protecting the environments that we go to," Grunsfeld said. The goal is "to make sure we don't contaminate other planets before we find out if we are alone in the universe," Grunsfeld said.

Nasa's ongoing Mars rover Curiosity has found evidence that the planet had all the ingredients and suitable habitats for microbial life to exist at some point in its past. Scientists have been trying to figure out how it transformed from a warm, wet and probably Earth-like planet early in its history into the cold, dry desert that exists today.

Billions of years ago, Mars, which lacks a protective, global magnetic field, lost much of its atmosphere. Several initiatives are under way to determine how much of the planet's water was stripped away and how much remains locked in ice in underground reservoirs.