Musings on a Wednesday Night
There’s never a dull moment in astronomy. If you’re a skywatching addict, then there’s something for you every night to check out. Last Saturday it was the Full Moon, and it was gorgeous! We didn’t get to see it rise here at the hacienda, but after it cleared the mountain in back of us, the Moon looked great. Tonight is quite clear (and cold), and so maybe later on I’ll step out and check out the starry skies. Right now, Sirius is twinkling low in the southwest and the stars of the Winter Circle are setting soon. Another sign that spring is here for those of us in the Northern Hemisphere, and autumn has arrived for the folks in the Southern Hemisphere.
Mars isn’t in our night-time sky right now. In fact, it appears so close to the Sun that it’s nearly impossible to see without help. But, even though it’s out of sight, Mars is not out of mind. Even the leader of Venezuela has been talking about the Red Planet this week, tying capitalism to the loss of life on Mars. I’m not precisely aware of when Mr. Chavez got his degrees in planetary science OR economics and political science, and I’ve not seen evidence of his research contributions to those fields, but I’m reasonably certain that the lack of life on Mars isn’t due to a plot against Marxist-Leninist paradises here on Earth. It’s amusing to read his rhetoric, even as you see it for what it is — getting in a dig at his neighbors to the north. It seemed like an unlikely topic for him to bring up, but then again, any world leader talking about anything to do with the sky (astronomy or planetary science-wise) catches my attention.
No, Martian life — if it existed — probably never got started down the long evolutionary path that we did here on Earth. Conditions on the Red Planet became untenable for that — not due to Adam Smith-style capitalism, which is a human construct that came long after life took root on Earth. More likely physical conditions were to fault on Mars, entirely NATURAL conditions that existed long before life on Earth was able to do more than look up to the sky in wonder. Changing conditions (atmospheric loss, cooling, geological changes) may well have doomed anything more complex than a Martian microbe to a very uncertain future.
As it turns out, if a group of scientists at MIT in Cambridge, Massachusetts are right, there’s a tantalizing possibility that life on EARTH may have its seeds on Mars, descending from organisms that somehow made their way from Mars to our planet in the very distant past.
It’s not so far-fetched as it might sound at first. There are some well-established ideas about Mars that lend themselves to this story and make it a plausible avenue of research into the origins of life on Earth.
First, early in solar system history, the climates on Mars and the Earth were much more similar than they are now. Life that arose and flourished on one planet could presumably have survived on the other — if it could get from one place to the other. Second, an estimated one billion tons of rock have traveled from Mars to Earth since the two planets formed. That material was blasted loose by asteroid impacts and sent on its way between planets. Eventually, the “stuff” from Mars hit EArth. Third, microbes have been shown to be capable of surviving the initial shock of such an impact. So, if there WAS life on Mars (in handy microbe form, which is an easy way to transport living material), and it somehow caught a ride on an outbound rock, then given a good set of orbital conditions, there would have been NOTHING stopping that rock and its life-load from getting here eventually. When you look at the orbital dynamics of our two planets, it turns out that the chances are a hundred times better for rocks to travel from Mars to Earth.
I know that sounds surprising, but life is amazingly resilient, and in fact, there is evidence such microbes could also survive the thousands of years of transit through space before arriving at another planet.
So if life got started on Mars first, and it got blasted off the planet in a meteorite impact, then some hardy microbes could have been carried here to Earth. And, if that’s true, then Ray Bradbury’s final scene in “Martian Chronicles” is more prophetic than he may have thought when he wrote it back in 1950. But, instead of finding those humanoid Martians staring at their own faces in a canal on Mars, all we have to do is look in the mirror in our homes here on Earth.
Of course, there’s a lot of work to do to prove this hypothesis, but I find it kind of poetic and interesting. We — you, me, Mr. Chavez — all the people on Earth — really COULD be Martians, and here all along we’ve been yearning to explore that RedPlanet so far away. And, we’re using technology that is the fruit of the capitalism that Mr. Chavez regularly decries on TV, radio, and the Internet — ironically enough, media methods that also depend more on capitalist investment than he might feel comfortable with.
But there you go. Astronomy and planetary science lead one down some interesting paths, and not always scientific ones. I think it’s rather interesting that even though his politics aren’t the same as mine, Mr. Chavez has an awareness of Mars and its past and future. I wonder if he stargazes, too?
I believe the Martian Connection (Mars-Earth transpermia) could have been much more alluring before. Then people had crustal cooling times in 100s of My AFAIK, or maybe the Last Heavy Bombardment was seen as the likely start of a habitable inner planet. While at the same time non-enzymatic biochemistry was supposed to be agonizingly slow. It may have seemed that an early start on the smaller Mars was a better bet.
Not that I’m an expert, but IIRC I have seen papers discussing possible and/or likely crustal cooling times in 10s or 1s of My. And some LHB papers has life modeled as a plague, you can’t really get rid of it once it has started.
At the same time appreciation of hydrothermal vent chemistry has happened. And now there is a paper that shows that biochemistry around boiling temperatures are sped up much more than traditional chemistry thought so can happen in 10s of years, not 100s or 1000s of My.
Figuring in the larger area of Earth and the likelihood of abiogenesis as a local event, Earth and Mars cooling at the same time would have life appear on Earth before Mars. Adding in crustal cooling times, impactor rates and travel times, it isn’t obvious (to this layman) which alternative is the likeliest even before admitting that much of these figures are poorly constrained. Meanwhile parsimony would have life started here, because it is observed here.
You raise some very good issues, and I doubt that this question will be answered satisfactorily until we can get a LOT of location samples from Mars. However, parsimony (aka Occam’s Razor) does seem to point to considering that it started here since we observe it here, but that seems like circular reasoning. There’s nothing to say it didn’t start elsewhere and take root here — and that would also support the spirit of your reasoning. Occam’s Razor doesn’t preclude the “life began elsewhere and migrated here” idea. It simply asks that we consider the simpler alternatives first before venturing out to the “wilder” ideas.