And to Michele's comment I try a thoughtful, somewhat provoked, and gentle return response . . . some stolen from my other thinkings I spent much of my life in the danger and cancer zone in harsh sunlight of an Earth's daytime summer, many times at altitude and for dawn to dusk stretches of time in a summer sun. I watch my skin where I can see it and am thankful for the ozone and the thin blanket of air we're grown to live under. Our numbers are such that we can really make it hard for our lives and other living things to exist on this world's surface. Life on Mars? Once? I am of a skeptical bent, by nature. I am accused of being a pessimist in the best of circumstances, always looking at the dark side. Not true! But still some baggage carried by me, others think. I copied out of "the harmless little asteroids" post, that I had written in response to The Wonderer, that there is a thing called Transpermia, and Panspermia, you may search for on the web and learn from. In those arguments, life is transported by the force of photons propelling seeds across the void. Or by comets delivered. And neither disagrees with the idea of evolution, just that the evolution started somewhere else. I have thought the fossilized life we detect at the 3+ billion years ago point in Earth's time was even then too complex to have 'evolved' from scratch in the billion years a steady surface of an accreting pummeled Earth had provided. And Francis Crick, of Watson and Crick, and the spiral helix of DNA discovery and fame -- also thought the DNA complexity of life had to be coming from somewhere else, seeing self assembly on a random nature not feasible to arrive at the complexity we see alive around us. Before his death, he, with others, still wondered, if the precursors of life, the complexity we see around us, but more so in the bacteria of 3.5 to 3.8 billion years ago little-changed now from then, how they could have been so complexly evolved then and from what? Did the precursors of bacteria and of all other life blow into the Earth, or ride a comet here to ground? If that be so, in fact, then a rain of things blown about the Milky Way Galaxy by photon winds, and gas expansions and gravity could indeed have brought more complex seed to Earth, and to Mars and to Venus, and to Europa, and to all the Worlds of our Sun looking for a place to sprout, but having the special design of life intrinsic. Yea! I hear them say that just shifts the problem of life's origin further away and further back in time to another "Creator." The late Fred Hoyle, (of Steady State Universe Fame and the man who coined the words "Big Bang" describing what has become our Standard Model), and a student friend now just retiring, Chandra Wickramasinghe, have carved out the field of Panspermia in scientific terms and investigations and carried forward mankind's knowledge of what kinds of complex organic things can and do form around red giant stars or red supergiant stars as they belch away their surfaces into space. And the Supernovae, launching the very metals and trace elements life exploits, as life lives. Those complex organic molecules: Poly Aromatic Hydrocarbons, formaldehyde, methanol and as we are learning -- nearly countless other complex molecules are formed in the 'empty' (planet-less) volumes of space around highly evolved stars. That might be where the Creator of the "way things are" decided to build the blocks and then insert the instructions to make these star born building blocks of life become more and more complex,and then blow them on stellar, magnetic, or photon winds about the universe. I like "seeder's of worlds" ideas, with vast time to perform the orchestral offering. For Earth, for example, the song of life can play for about 7 billion years or so, total. Mars once did have water and still some locked in side it and copious amounts of oxygen locked in the rock and soil, but not enough gravity to hold a moderating envelope of gas. Life could have had a beginning shot on Mars, and life could still be being carried out 'neath the thin mist and dusty layer of the Martian surface. I hope so. Religions should be very vast, not limited to one special group of animals and focused on a single world. If anyone wants a God -- I insist he choose a really Big God who writes the rules of nature and commands the future in His plan. Me religious, No. It just may seem so, but there is a reverence. So I hope we find evidence of life on Mars, and bet it's foundation similar to our own. Gee, life everywhere you look almost! Well there ARE rules, the Laws of Nature. I copied and pasted this from my other post, probably not very eloquent, but heck, you see me and I'm not very eloquent. ========================== IF, Poof! we could WISH for Mars a Ball of Air, and magically it would appear and provide enough Air for us humans to breathe and walk around in, suit-less,and thereby naked in some cold Martian wind -- this whiff of Air would only last 60 million years, but likely it would only be mere tens-of-thousands of years before the surface partial pressure would not give us a breath. That Air our wish would wrap the Red Planet in for our little walk would be but centuries or mere millenia in escaping to space and thinning so our breath would be ever shorter as time moved forward. Yet it is a place worth going to, since there seems a drive we have with other life to persist through time. I have not worked the physics, but could, or suggest bright students here think through the numbers, and see when those pressures would be like ours here less, than Everest on Mars' surface. If our wish were granted and the gas around thei Mars so built how long would we have for breath?