In the small hours of this morning, NASA scientists announced that their Mars Reconnaissance Orbiter had found evidence of flowing water on the red planet. In an official statement, the US Space Agency said:

New findings from NASA’s Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars… Our quest on Mars has been to ‘follow the water,’ in our search for life in the universe, and now we have convincing science that validates what we’ve long suspected.

So what does it all mean? We caught up with our very own Dr Paulo de Souza, a collaborating scientist on NASA’s earlier Exploration Rover mission, which landed two large robots on the surface of Mars.

Here are five things you should know about today’s discovery.

There is water on Mars

Erm, didn’t you already tell us that? Well yes, but as Dr de Souza explains, there’s an important distinction to be made.

“The story of water on Mars started when the composition of a meteorite found in 1984 in Antarctica revealed two things: large traces of carbonates, which need water to form, and a composition very similar to rock samples taken from Mars back in the seventies. There was no doubt that it came from Mars,” he said. Later a number of structures that resembled fossilised bacteria were found in this meteorite, but this claim is still controversial.

Fast forward to March this year, NASA found evidence that about one fifth of the planet’s surface was once covered by an ocean. Curiosity rover also found evidence of water vapour in the atmosphere. But this discovery does not close the water cycle.

“So the notion of Mars having once had water is nothing new, but this is different- this time scientists have actually found deposits of water.”

We’re not alone in the Universe…probably not anyway

Take a moment to let that sink in. Life may exist in another part of our solar system, right now.

“There are three key elements for life: nutrients, energy and water. Mars is rich in nutrients, gets its energy from the sun and now it has water. If you have water, you have life,” said Dr de Souza.

But we’re probably not talking about little green men.

“Large, complex forms of life as we know it need large water deposits sustained for long periods of time to grow and evolve. Life on Mars, if exists, is more likely to be in the form of minute microbes.”

You could be living there one day

You’ve probably heard that old chestnut before. Just last month Buzz Aldrin announced he was combining with scientists to develop a ‘masterplan’ to colonise Mars by 2039, the 70^th anniversary of the moon landing.

But the discovery of water on Mars is a potential game changer.

“Having water available makes the prospect of Mars sustaining human life all the more real,” said Dr de Souza.

But there are still major challenges to overcome.

“Mars is a very hostile environment. Its atmosphere is very thin and has only a tiny concentration of oxygen making it impossible to walk in the open air. It’s exposed to high levels of solar radiation, extreme temperatures and severe sandstorms with winds up to 400km/h,” Dr de Souza said.

And the water NASA has found is very salty.

“Imagine if you had a little bit of salt on a plate and threw some water on it, the water would then be salty. The surface of Mars is like a salty plate.”

You’re probably not as special as you thought you were this time yesterday

What is it with humans and our insatiable desire to diminish our own importance?

“500 years ago we thought we were at the centre of the Universe, with everything revolving around us,” said Dr de Souza. “Then scientists demonstrated that the earth revolved around the sun, and all of a sudden there was something more important than our planet.”

About 300 years later scientists discovered that our sun was just another star. And how many stars are there in the Universe?

“Go down to Bondi Beach, take a handful of sand and try to count how many grains there are. Then imagine trying to count the grains in a truck full of sand. Can you now try to imagine how many grains of sand there are on Bondi Beach? There are more stars in the Universe than grains of sand on planet earth.”

But still we desperately clung to our sense of importance, safe in the knowledge that we lived in the only solar system in the Universe…..until the discovery of planet HD 114762 b was discovered in 1989, followed by numerous other sun orbiting planets.

Now we’re facing the very real possibility of finding life outside of our planet. Tough time to be a human.

This is just the beginning

The discovery of water on Mars will help to shape future missions to the red planet.

“Perhaps the greatest thing about this discovery is that it provides a cornerstone for future missions, as we now know what to look for,” Dr de Souza said.

“We are still in the very early stages of space exploration; just learning to go out of our cave and start to explore. It’s a very exciting time to be a scientist.”

Our Canberra Deep Space Communication Complex has supported NASA’s Mars Reconnaissance Orbiter, relaying commands and receiving images and data from the orbiting spacecraft high above the red planet over the past decade. Want to know more about our space and astronomy work? Take a look at some of our cosmic highlights from earlier this year.