Life from Mars
The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock. ~ American chemist Steven Benner
In the early 20th century, American astronomer Percival Lowell, seeing what he termed “non-natural features” on Mars, speculated that Martians had an advanced civilization, replete with crop irrigation via canals drawing water from the planet’s poles.
The molecules that combine to create genetic material may have needed more than whatever primordial prebiotic soup might have been cooked up on Earth 4 BYA.
Adding energy to organic compounds does not generate RNA. It merely makes tar. Rendering RNA requires atoms to be coaxed into shape by templating atoms on the surfaces of crystalline minerals.
The most effective minerals for patterning RNA would have dissolved in the oceans of early Earth, at a time when the planet was probably enveloped by ocean. Mars still has extensive, deep reservoirs of water, little of which stays on the surface for long.
Further, while water is essential to life as we know it, it is also corrosive to biopolymers such as RNA. The long strands needed for information storage can’t form in water.
The best RNA templating minerals are boron and molybdenum. Both are water-soluble.
Oxygenating boron births a borate (BO3). Add oxygen to molybdenum to make a molybdate (MoO4 2− and variations).
Borate minerals prevent the organic building blocks of life from devolving into tar. Molybdate can bond to the carbohydrates that borate stabilizes and catalyze a rearrangement into ribose: the R in RNA.
Besides an uncongenial aquatic surface, for lack of free atmospheric oxygen, both borate and molybdate would have been practically nonexistent on early Earth at the time life arose. In contrast, 4 BYA, the atmosphere of Mars had much more oxygen than Earth.
The early history of Mars seems to have been very similar to that of Earth, especially with respect to the ancient hydrosphere. ~ American geomicrobiologist Nora Noffke
Life may have evolved on Mars. From around 4.5–3.5 BYA, Mars was habitable, at least by hardy microorganisms. Even now, Earth methanogens could survive there.
While organic compounds were produced on Mars, there is no extant evidence that life ever emerged. Exploration of Mars has been slight; we know little.
The scenario of life coming to Earth from Mars seems a simple 2-step. A meteorite knocked a Martian rock with stowaway microbes aboard into space. The Martian transport becomes a meteorite that splashes down on Earth.
It is possible that a violent impact could eject material without generating so much heat that it would destroy a microbial passenger, especially if the traveler were shielded in the interior, not on the surface; likewise, in entering Earth’s atmosphere. Life nestled inside a meteorite would have a better chance of surviving the searing heat in coming down.
If Martian microbes hitched a ride on a dust particle, blistering heat may have been avoided by a gentle deceleration. But then there is the issue of travel time.
Most earthbound bits spend a long time in space. One Martian meteorite traveled for 15 million years before landing on Earth. But 1 out of 10 million objects make the journey from Mars to Earth in less than a year. This would minimize exposure to ionizing interplanetary radiation.
That said, some microbes that exist now are highly resistant to radiation, as well as being able to handle the jostle involved in projectile space travel.
As with heat, the best place to not be radiated would be inside a sizable rock. Such comfortable snuggling would also help preserve a habitat.
But then, suspended animation is possible. And pebbles are more likely to make a quick trip than boulders.
The timing of life traveling from Mars to Earth would have to have been fortuitous. Mars had a relatively oxygen-rich atmosphere 4 BYA, but its magnetic field disappeared around that time, allowing the solar wind to strip the atmosphere away.
