Is the inner solar system one big swimming hole?
The discovery of what is by all appearances is a dry stream bed on Mars by the Curiosity rover this week adds to a growing body of evidence that sometime in the distant past, at least portions of the Red Planet once more closely resembled our own blue marble, somewhat inappropriately named “Earth.”
For Mars, which for centuries, even millenia has loomed large in human literature and myth, there is something familiar and unusually compelling about a dry stream bed, which scientists at JPL now suggest once ran on a very human scale, “ankle to waist deep.” We may find it difficult to grok methane lakes on Titan, or vast reserves of water feeding a black hole in deepest space, but this is instantly understandable, a point driven home by JPL with a comparative photograph of a similar bed in the high Chilean desert.
Although a far dryer place than it once was, for those who look to the future, and to creating on Mars a second home for the human race and second branch of human civilization, it seems that with a massive polar ice cap and what look suspiciously like seasonal water flows from crater walls, Mars is clearly wet enough, at least to make a start.
What comes perhaps as a bigger surprise, is the clear signature of water trapped in hydrates on the large asteroid Vesta, orbiting beyond Mars in the main asteroid belt. NASA’s Dawn spacecraft departed Vesta earlier this month en route to Ceres, but among the wealth of data gained in over a year’s orbit of the near mini-planet was the unsuspected presence of significant quantities of hydrates, apparently deposited in small particles over a defined period, perhaps in a similar manner and at the same time a primordial Earth was accumulating water as well.
What is gradually emerging is a basic understanding that water, contained in a multitude of forms, was once distributed throughout the inner solar system, and much of it still remains. Knowing it is there is one thing, accessing it is something altogether different. But for the moment, the mere presence of water signifies at least the potential for expanding exploration, commerce and civilization throughout much of the inner solar system based on near term technology, no unobtanium required.