Monday, 8 December 2014

Atlas and Pan - Saturn's Generation Ships

With over sixty moons and its complex ring system Saturn is one of the most diverse and intriguing regions of the Solar System. While a lot of scientific interest is directed at the planet's largest moons, such as Titan and Enceladus, the two most interesting to me are two of the smallest: Atlas and Pan.

Atlas and Pan, Saturn's most intriguing 'moons'

Both the moons are shepherd satellites, part of a small group of moons that are said to maintain Saturn's rings' sharp and well-defined edges. But the appearance of these two moons is not at all what you would expect if they had formed naturally. They look extremely unnatural, in fact.

They probably are.

Both moons are likely to be the long abandoned remains of two advanced generation ships. These vast vessels, capable of supporting hundreds of thousands of individuals for tens of thousands of years, were probably in the Saturn system attempting to harvest anti-matter to use as fuel, perhaps for their Alcubierre propulsion system. Such as propulsion system for such large spacecraft would require a significant amount of anti-matter, but obtaining this amount would be feasible at Saturn (or indeed Jupiter). It's estimated that up to a kilo of anti-protons enters the Solar System every second, which will become concentrated in the magnetic fields of the giant planets. Despite this, it does seem that Atlas and Pan were not able to collect enough in time to escape.

Over many millions of years the spacecraft have attracted a lot of dust and debris from Saturn's rings, which is why their appearance is now moon-like, at least in their bulging central sections.

The diagram below shows the possible interior of Atlas (click to enlarge). Pan is no doubt similar:

A mission to those moons is long overdue. A lander is required, one that can drill deep into the crust down to the hull beneath. And later a manned mission to enter one of the giant ships. Only then will we begin to understand why they visited Saturn, and why they had to stay. Perhaps we will find the occupants, some even surviving in deep hibernation awaiting rescue. And we may be able to reverse engineer the technology we find to accelerate our own advancement towards interstellar travel.

It's entirely possible, of course, that the ship, although stranded, is otherwise functioning perfectly normally (the anti-matter it managed to acquire could be more than enough to run the ship's systems for millenia, even though the Alcubierre propulsion system is not able to function). It's occupants could be living out their lives, generation after generation, totally oblivious to their predicament, trapped in the 'planned ignorance' phase of their journey by the ship's controlling intelligence (such a phase would continue to avoid the risk of some occupants developing the desire to escape. Only when the destination system was reached would the current generation receive education on the ship's purpose and their colonisation mission).  Finding such an orbiting colony would be a momentous discovery.

The overriding reason for such a mission is that it may be essential to our immediate survival. If the 'Atlas' and 'Pan' generation ships have indeed collected some anti-matter their storage facility may have degraded and be at risk of failure. Such a failure would set off an anti-matter explosion that could be catastrophic, even here on Earth, and prematurely end our civilisation.

It's a chilling prospect, and one that should not be ignored.

Tuesday, 11 November 2014

The Cloud Tops of Venus

Of all the solid worlds in the Solar System, Venus has to be the worst place to settle a surface colony. The average surface temperature is 462 degrees Celsius, the air pressure is 90 times that of Earth, and the atmosphere consists almost solely of carbon dioxide. The sulfuric acids clouds only add to the already hellish conditions. Even the most hardened landers sent there so far, the Russian Venera probes, lasted only a few hours before being destroyed. It seems that a surface colony is out of the question for humans.

But what about high up in the atmosphere?

At an altitude of around 53 kilometres, right at the cloud tops, the air pressure and temperature is much like that at Earth's surface. The air is not breathable, and there would still be the sulfuric acid clouds to deal with at times, but it is more than possible to construct suitable floating habitats for that region with our current technology. And because air we breath is much lighter than the atmosphere of Venus it makes an ideal lifting gas, much like helium does in our atmosphere. Some type of airship would be ideal as humans could live directly inside the aircraft's 'balloon'. It would make for a very spacious habitat. Something similar was proposed by Russia back in the 1970s, so this sort of thing has been discussed for decades.  

Russian idea for floating Venus colonies
It is plausible, affordable, and something that would be essential to diversify our habitats, and the lessons learnt would be invaluable when making colonisation attempts high in other atmospheres, such as those of gas giants.

A recent NASA proposal for airship colonies on Venus

Despite the extreme conditions on Venus, there is possibly some evidence that life of some sort may be down there. A Russian researcher has suggested that the Venera 13 lander photographed lifeforms that were disturbed by the lander's touchdown. Further lander missions should be sent to investigate his claims, and it seems such a mission could happen in the 2020s. I've recently discovered that Russia is planning to send a rover to Venus during that decade. I will be watching with great interest.