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Mars Orbiter Finds Evidence For Ancient Rivers, Lakes
Cowards Anonymous points out news that studies based on data from the Mars Reconnaissance Orbiter have found that vast regions of Mars contained rivers and lakes when the planet was young. The studies also suggest that the water existed for quite some time, often in standing pools, which are conducive to the formation of basic organic matter. NASA provides a color-enhanced photo of a delta within a crater. Quoting:
"The clay-like minerals, called phyllosilicates, preserve a record of the interaction of water with rocks dating back to what is called the Noachian period of Mars' history, approximately 4.6 billion to 3.8 billion years ago. This period corresponds to the earliest years of the solar system, when Earth, the moon and Mars sustained a cosmic bombardment by comets and asteroids. Rocks of this age have largely been destroyed on Earth by plate tectonics. They are preserved on the moon, but were never exposed to liquid water. The phyllosilicate-containing rocks on Mars preserve a unique record of liquid water environments possibly suitable for life in the early solar system."
They had plenty of greenhouse gases. The problem was that after the geomagnetic field of Mars was lost, the solar wind was able to strip away the atmosphere, leaving it today at about 5 to 10 millibars (in contrast with the Earth which is about 1000 millibars).
Martian geological time is subdivided into a number of time periods based upon major geomorphological features seen from orbit -- major crater basins, the density of craters (generally speaking, crater frequency was higher in the deep past -- as on the Earth's Moon), canyons and channels such as Valles Marinaris, and volcanoes. While it isn't possible to determine their exact numerical age, it is possible to figure out their relative age (i.e. the order of the events that made them). For example, the overlapping shapes of craters tells you which impact formed first. If a volcano has a crater on it, then obviously the volcano formed first and then the crater. If a channel is eroded into a crater, then the channel came after. That kind of thing. So, there's a reasonably detailed relative chronology for events on Mars, and this is divided into eras known as (from oldest to youngest) the Noachian, the Hesperian, and the Amazonian.
Using crater densities and the fact that rocks were recovered and dated on the Moon, it is possible to link the better-known chronology of the Moon to that of Mars. There are significant uncertainties of course, but generally speaking that allows people to estimate that the Noachian was from about 4.6 billion to about 3.5 billion years ago, essentially the time when the cratering frequency started to drop off on the Moon. There is ample evidence that at this time on Mars there was freely-flowing water on the surface, hence, "Noachian".
The pages cited above has some really nice charts and descriptions, and the wikipedia page has a map showing the distribution of the deposits of different ages.
The gist is that as the atmosphere was stripped away and the grew too cold and low pressure for surface liquid water to persist for long enough to cause obvious landforms, it was going into underground aquifers and ice deposits. Every now and then a big transient source of heat (volcanic eruptions or magma plumes in the mantle, and impacts, basically) deliver a big pulse of thermal energy that melts a large quantity of water. Result, landforms like canyons, areas with very large boulders that were carried from "upstream" by the floods, etc. There are other causitive agents, eg collapse of crater-rim walls releasing lake water, ice damn collapse, Milankovic cycles warming areas, polar wander... (and if the new idea about the lowlands results from a gargantuan impact are correct, it seems likely that the upper crust migrated significantly over the planet to reach an equilibrium position with the lowlands at one pole or the other, the Tharsis bulge (Olympus Mons et al) near the equator, etc.
Short answer: all eggs in one basket.
Earth wasn't always the almost paradise for human-like life that is still a bit today, almost all life was wiped several times in earth history. And that, without our "intelligent" intervention (why wait for a huge asteroid or a snowball earth period if we can destroy it all faster?). Don't waste money in this and humans will become a rich, but unfortunately extinct, race.
One of the ways of having a backup is to be also somewhere else, preferably self-sustained. Exploration could give answers to this, can our life be sustained on Mars? Of all other planets in the solar system, mars is the best bet so far. And if not, could end being a good place to get mass resources (for i.e. building massive enough self-sustained space stations) without worrying about ecology here.
Even without watching it as a future colony, exploration could lead us to new discoveries, new knowledge that could prove to be useful, or even essential, for our future.
Yes, this can be done later, but at some point later will be too late.
This statement is, uh, mistaken. What it's getting at is the notion that long periods of exposure to water is generally considered to be probably very very important if not essential to early life. ("organic matter" would be anything with a carbon atom in it, e.g. coal, plastic, methane, oil..
Coal, plastic, methane, and oil are all byproducts of life. Coal is from plants, plastic is from humans, the vast majority of methane is from biogenic sources, and oil is from plants, animals, and bacteria.
The only carbon product you mentioned that might be formed without life is methane. The formation of methane usually involves water as either a reactant or product. In fact, simply burning methane produces water.
I don't think there is anything wrong with the statement you are disagreeing with" standing pools, which are conducive to the formation of basic organic matter." It's possible water isn't a necessity for life and substantial quantities of carbon compounds. But, that statement simply asserts that water is conductive to the formation of carbon compounds, this is definitely the case.
No. If you wield a magic wand and warm the planet to the point that the polar caps and underground ice melts, you've only got a few thousand / tens of thousands of years before it's all boiled off into space. Low gravity, no core magnetic field.
... Up until 60 years ago, traveling between the USA and Europe was on the order of months of time, rather than hours.
Excuse me? Believe it or not, we had something better than sailboats, even before 1948. The great trans-atlantic passenger lingers (e.g. the Titanic) would go between the USA and Europe in under a week. In 1938 (70 years ago), the Queen Mary did it in 3 days.
"Convictions are more dangerous enemies of truth than lies."
You're talking total tripe, because we don't need free energy nor wormholes nor warp drives nor any other nonexistent inventions nor any new physics to make travelling to Mars cheap and widely available. All we need is *time* (a lot of it) for our engineering systems to mature.
Travel is a matter of harnessing energy, and energy is plentiful. The earth's surface receives a bit less than 150,000 TW of solar irradiation, of which we harness and use no more than 18-20 TW (that's just 20, not 20,000), so there's no energy shortage at ground level. Add solar energy collection beyond the atmosphere to our capabilities and the available energy becomes effectively infinite. That also means that travel within the solar system will be effectively unlimited in an easily forseeable future. It's a sure bet. The sun isn't going to dim any time soon.
What we do need of course is many centuries of good solid engineering to develop such a capability, because creating an infrastructure for widespread space travel is not something that can be done in just a few decades. But it's coming for sure, because there are no reasons why it shouldn't come and ample reasons why people will want it ... no doubt it will be fueled by the lure of profits like everything else.
We certainly do not need a change in the laws of physics nor any magic transports. Stop talking crap.
(New physics will undoubtedly appear over the centuries, but current physics is more than enough as a foundation for universal space travel. Energy is the only hard constraint on space travel given by the laws of physics, which effectively means that we are not constrained at all, at least within the inner solar system.)
"The question of whether machines can think is no more interesting than [] whether submarines can swim" - Dijkstra