Final frontiers

NASA has announced that it’s considering sending a robotic ship to sail the methane oceans of Titan echoing the golden age of maritime exploration — but are there any final frontiers closer to home?

I was in my final year of university when the Huygens probe beamed back pictures from the surface of Titan, Saturn’s largest moon. I, like many others, was captivated by those scenes of dried-up lake beds, river channels and smooth pebbles. There were both striking similarities and alien differences to our own world — and faint echoes of bygone eras of exploration here on Earth.

I was reminded again of this by an excellent recent documentary on BBC Four — Destination Titan — which covered the efforts of the British team led by John Zarnecki who designed the set of instruments that first sampled the then mysterious surface of the moon.

And now this week NASA has announced that it’s seriously considering a project to send a robotic ship to sail the liquid methane oceans of Titan to characterise the moon’s complex organic molecules in detail — offering even stronger parallels to maritime explorers of 16th century Europe.

But in an age where satellites map every inch of the earth’s surface in ever greater detail, and detailed data is available to anyone with a decent internet connection, are there are any ‘final frontiers’ closer to home?

Perhaps. In April this year Richard Branson officially launched his Virgin Oceanic project. Although clearly riding off the back of the publicity of his Virgin Galactic commercial space venture, Oceanic will not ferry passengers but take a small team of scientists in a submarine to the deepest point of the Pacific Mariana Trench at 11km.

Although humans have briefly touched down to similar depths before with the 1960 Trieste mission, that was in a bathyscaphe sub that essentially just moved straight up & down like a hot air balloon.

Oceanic’s unique design complete with hydroplanes (akin to the wings of  an aeroplane) and thrusters will allow it to ‘fly’ along the bottom of the trench for around 10km collecting video and data from a world that may be teeming with novel biodiversity.  

An even more tantalising project is being led by Professor Damon Teagle of Southampton University who plans to bore down to the centre of the earth to retrieve never before studied rock samples from the mantle. Teagle is currently leading an expedition in Costa Rica to get the first ever samples of the lower oceanic crust — the material lying just above the mantle - and hopes to go deeper, right into the mantle, by 2020.

‘Drilling down and retrieving samples directly from the mantle would provide scientists with a treasure trove comparable to the Apollo lunar rocks, giving insight into the origins and evolution of our planet,’ he said, adding: ‘There is a surprising level of interest from the world’s media and engagement by the general public in this frontier endeavour.’

Teagle says that the basic technology is in place, with the Japanese drilling ship Chikyu. Launched in 2002, it can carry 10 km of drilling pipes and  has a riser system capable of recovering cores from great depths.

However, he says researchers and engineers will have to design and develop new drill bits, lubricants and wireline instruments to make coring into the mantle possible, at pressures as high as 2 kilobars and temperatures up to 300 °C, and beneath about 4 kilometres of water.

Interestingly, the closest we have gone before to sampling the mantle was a project headed by Harry Hess, a founding father of the theory of plate tectonics.

At a US National Academy of Science meeting in April 1958, when defending the project against detractors he said: ‘Perhaps it is true that we won’t find out as much about the Earth’s interior from one hole as we hope. To those who raise that objection I say, if there is not a first hole, there cannot be a second or a tenth or a hundredth hole. We must make a beginning.’