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These moons are better than planets

There may be life on moons of Saturn and Jupiter because, as Cassini has shown, they have liquid water and heat.

Our solar system's moons may have more potential for life than the planets themselves. That’s the message that Nasa’s Cassini-Huygens spacecraft, now exploring the surface of one of Saturn’s moons named Dione, is beaming back to earth.

In March this year, scientists found that Enceladus, a small moon orbiting the giant ringed planet Saturn, is likely to possess an ocean containing hot water under its icy crust, raising the prospects that it could host life.

Situated some 850 million miles (1.3 billion km) away in the outer solar system, icy Enceladus seems an unlikely place for liquid water. But gravity measurements taken by Cassini indicate the moon contains an underground ocean in its southern hemisphere. The ocean, likely to be sandwiched between the moon’s rocky core and its ice-covered surface, is believed to be at least as big as the USA’s Lake Superior.

Cassini’s Cosmic Dust Analyser helped the scientists find dust particles in one of Saturn’s rings came from plumes erupting from Enceladus. They contained silica nanoparticles probably formed in chemical reactions between the water and the ocean floor’s rocky core.

Associate professor at University of Tokyo, Yasuhito Sekine, analysed the silica nanoparticles and revealed that the ocean contains water at least 90-degree Celsius (194-degree Fahrenheit) in temperature, which makes the small planet a possible host of living organisms.

“It’s very rare that liquid water and heat exist at the same time and have strong chemical reactions between them; it has never been found in any places in the universe other than earth,” Sekine said.

Researchers aren’t sure what causes the heat, but Sekine posits that the water could have formed and be sustained by tidal heat from gravitational tugging by Saturn and sister moons on Enceladus.

Life would be difficult to sustain on Enceladus without an internal heating system because the Saturnian moon is too far away from the Sun to receive its warmth.

Sekine said his findings may lead human beings to encounter alien life. “We knew that Mars might had liquid ocean and heat in the past, but now it’s a cold and dry planet. But the Saturn moon, Enceladus, has liquid water and heat reacting to each other, which is a new discovery that raises the possibility of that there may be living organisms,” Sekine said.

Enceladus, which is only about 300 miles (500 km) in diameter, is one of the few places beyond Earth likely to contain oceans, along with Saturn’s large moon Titan and Jupiter’s Europa and Ganymede.

Only Enceladus and Europa, however, show evidence that their oceans are in contact with rock. Scientists are working on follow-up missions proposed for both Enceladus and Europa.

However, it will take decades for scientists to collect more concrete evident to confirm the existence of living organism in Enceladus.

“It will take more than 20 years to send a space probe to Enceladus and bring samples back to earth. So, we’re taking a long breath until we finally get the sample in our hands – maybe more than 30 years - but hopefully by the end of this century, we will reach the conclusion,” Sekine said.

With inputs from Reuters