A prominent jet and other outflows are evident on this image of 67P, a comet packed with organics, taken from Rosetta on Jan. 31. Image credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Feb 8, 2015 The quest to find alien life in the Solar System

Sen—I’ve just enjoyed the latest AstroFest event in London, a two-day extravaganza for astronomers and space fans that has become the UK's must-attend highlight of the year.

Beyond the forests of telescopes for sale that had everyone drooling, the lecture sessions starring some of the world’s leading scientists were all packed to capacity.

A variety of topics took us right across the Universe, but a few focusing closer to home reminded us of the adventures that lie ahead in looking for signs of life in our own Solar System.

We had no less than three contributions from scientists working on ESA’s incredibly successful Rosetta mission to explore Comet 67P/Churyumov-Gerasimenko. 

Fred Jansen, Rosetta’s mission manager, gave a recap of what’s been achieved so far, including the news that lander Philae tasted organic material on two of the locations on the comet’s surface where it bounced before it came to a rest. 

And he rounded off by displaying the latest Navcam image, released just an hour or so earlier showing 67P’s nucleus actively spouting jets. You can see a crop of it as our main picture.

The following day we were treated to more Rosetta science from Stephen Lowry, a member of the OSIRIS team that is taking high-resolution images of the comet, plus a breathtaking account of the drama behind Philae’s unconventional touchdown by Barbara Cozzoni, an operations manager for the lander at DLR, the German Aerospace Centre in Cologne.

Comets are, of course, of fundamental interest to those seeking the meaning of life because scientists believe they may have carried water and the building blocks from which life formed.

In another presentation, Professor Ian Crawford spoke about Lunar Mission One (LMO), the private project to return a probe to the Moon’s surface and drill up to 100 metres into the soil, or regolith. As Crawford says, we have so far only scratched the surface of the Moon.

It is a sterile, dead world, but Crawford has speculated before that the regolith could contain microscopic fragments of alien tech that might have got there millions of years ago, after drifting across space, and been preserved in the airless environment.


Target moons for the JUICE mission are, from left, Europa, Ganymede and Callisto. Image credit: NASA

LMO intends to leave its own souvenirs of life alien to the Moon, by planting time capsules in the holes it drills, containing contributions from those who have given most generously to crowdfund the venture.

Crawford pointed out that such deep drilling will be vital on Mars too, because many believe that if life still exists on the Red Planet, it will be underground, due to the levels of radiation that bombard the martian surface from space. 

But there is also a growing belief that we might have a better chance of finding life beyond the Earth by going to explore the icy moons of the giant outer planets. A number of these orbiting Jupiter and Saturn are reckoned to have underground oceans of liquid water.

Cassini has tasted the salty spray from one of Saturn’s larger moons, Enceladus, and in the past week, NASA confirmed funding for a mission to Europa, one of the four main Galilean satellites of Jupiter.

Enceladus appears to be a prime candidate to study for possible life. And as leading Cassini scientist Carolyn Porco told my Sen colleague Elizabeth Howell this week, exploring Europa will bring our knowledge of that moon up to a level similar to our current knowledge of Enceladus.  

ESA is also visiting Jupiter in the next decade, with a probe called Jupiter Icy Moons Explorer, or JUICE for short. As well as Europa, it will fly close to Callisto and Ganymede. All three moons are believed to have liquid water, thanks either to gravitational churning or antifreeze-like chemistry.

A lead scientist on the JUICE mission, and on Cassini too, is Professor Michele Dougherty, of Imperial College London. She told the AstroFest audience why the moons of Jupiter and Saturn a hold such fascination for astrobiologists.

I have asked Dougherty about the prospect for life on moons of Jupiter before. She told me: “Four different conditions are necessary for life to be able to form. You need water. You need a heat source. You need there to be complex organic compounds like carbon, nitrogen and methane and things like that and you need there to be a stable environment over time. 

“We are certain that we have those conditions at Europa. it is very likely there will be the same conditions at Ganymede. 

“JUICE will check whether those four conditions are present and, if they are, then that means that there is the potential for habitable zones to exist at those moons. I would be flabbergasted if we didn’t find that those four conditions were present at at least one of the moons.”

Could humankind need any greater spur to intensify its exploration of our own planetary neighbours?