Saturn and it magnificent system of rings and moons is one of the most fascinating regions of the Solar-System. And it's fascinating not only because of its natural history, but because of its likely unnatural history, too.
In a previous article I wrote about the strong possibility that Saturn's two small and unusual moons, Atlas and Pan, could well be abandoned interstellar starships.
|The most recent images of Pan, one of Saturn's unusual, and possibly artificial, moons|
But there are two other objects in the ringed planet's system that are of extreme interest: the large Moon, Iapetus, and the tiny moon, Daphnis.
IapetusIapetus is the third largest moon of Saturn. There is much about the moon that is intriguing, but the most intriguing to me is the massive equatorial ridge that runs almost completely around its circumference. At around 20 kilometres wide and 13 high it is a truly monumental feature, especially for a moon only 1,492 kilometres in diameter.
|Iapetus - the third largest moon of Saturn|
Why is such a feature present, and how can it be exactly on the moon's equator?
The only plausible natural explanation given so far is that Iapetus once had its own ring system similar to its parent world. The rings, formed from the debris of a colliding smaller object, or from the breakup of Iapetus's own moon, rained down onto Iapetus's equator, eventually forming the ridge.
That is an interesting theory, but it does not explain why the ridge is not evenly distributed across the entire equator. Almost a quarter of the equator does not have the ridge. Falling ring debris would have been distributed over a long period of time, and very evenly.
|The ridge (centre) that runs three quarters of the entire length of Iapetus' equator|
The most likely unnatural possibility is that the ridge is actually a collapsed orbital ring. Tethered to the moon, such a structure would provide easy access to and from the surface, and would be quite an obvious facility for an advanced space-faring civilisation to construct.
|An orbital ring, such as this one seen here around Earth, could have collapsed onto Iapetus creating the ridge|
Abandoned for thousands of milennia, the structure would eventually decay and collapse, crashing to the surface along the equator of Iapetus. Once the collapse had begun it would progress rapidly, which would explain the unevenness of the ridge, both in its height and its distribution. A gap in the ridge, which we can clearly see, would be highly likely in this scenario.
If this happened it must have been a billion or more years ago as subsequent comet impacts have covered the remains of the ring in ice and debris hundreds of metres thick.
If evidence of a collapsed orbital ring is found beneath the ridge's ice it would provide strong support for the other potential evidence of ancient extra-terrestrial activity in Saturn's vicinity.
A mission to Iapetus is required, which must include an orbiter with ground-penetrating radar to map the remains of the orbital ring, and whatever else may be hidden beneath the equatorial ridge. And if the presence of the orbital ring is confirmed, a manned mission should be launched as soon as possible with the aim of setting up a long term colony on the ridge. Despite the long period of time that has passed since the ring collapsed there would still be plenty of artifacts present that could teach us a lot about the advanced culture that once thrived in the Saturnian system. And there may be clues as to the reason for their demise or departure.
|A large human colony on the ridge, established after the collapsed orbital ring theory was proven correct.|
DaphnisDaphnis is one of Saturn's small inner moons with a diameter of just 8.6 kilometres. It orbits within a gap in Saturn's A ring, known as the Keeler gap. In fact, the main reason the gap remains clear of debris is largely because of this moon.
|The best current image of Daphnis taken by NASA's Cassini orbiter|
One thing Daphnis has in common with the other moons of interest, Atlas, Pan and Iapetus, is that it has an equatorial ridge. This ridge could well be the result of particles falling to the surface from the surrounding ring debris, but the fact that it is on the equator once again makes this highly unlikely. It is more likely to be dust gathering on the shape of the moon's structure, as in the case of Atlas and Pan. And just like Atlas and Pan, the shape of Daphnis suggests it is unnatural in origin.
|Saturn's moon, Daphnis, nestled in the Keeler gap within the planet's A ring|
The apparent abandonment of so much technology in Saturn's system suggests that the civilisation that developed it had to make a rapid exit (or suffered a catastrophic disaster). They did, however, have the time to place at least three of their vast spacecraft within or very near to Saturn's huge ring structure. Such a move would conceal them from discovery from anything observing from afar. The build up of dust and debris on their hulls has disguised their presence even further.
Daphnis deserves significant study.
The incredible Cassini mission will come to a spectacular finale towards the end of 2017. A new and even more ambitious mission to Saturn is now required. As I mentioned before it must include an Iapetus orbiter with radar capable of mapping objects beneath the icy surface, but it must also include rover missions with deep drilling capability. There must also be probes to explore the moons within the ring system, with Atlas, Pan and Daphnis the priority. We need to know whether or not a manned archaeological expedition is required to study and exploit the ancient technology that may be present.
The exploration of any signs of extra-terrestrial technology within our Solar-System should be one of the top priorities of Earth's space agencies. Such exploration could result in the knowledge we require to preserve our species beyond the Earth's demise.
When you think about that, any concerns about the cost of such an undertaking pale into insignificance.