NASA's Mars exploration plans need 'paradigm shifts' to succeed, report finds

[Unclear Engineer]

Well now, the "synthetic biology" described in your link for "decontaminating" the Martian soil of perchlorates seems like that "energy cycle" that you say is missing from other worlds besides Earth. Why would you be surprised if that biological process already self-initiated on Mars sometime in the distant past?

But the perchlorates in Martian soil is not the kind of "contamination" I am worried about. I am worried about introducing Earth's life indicators into the Martian environment before having an opportunity to search for life indicators that could be of Martian origin.

So, this link just further increases my concern that working to "colonize" Mars too soon could preclude some important scientific work on life in the universe beyond Earth.

 

[contrarian]

There are only 6 Earth-sized exoplanets found so far orbiting G-type stars. The better case may be one orbiting an F8 star [KOI-4878 b].

Since the distance to these 6 Earth-sized exoplanets is known, as well as all the other exoplanets, is there a guess as the the number of Earth-sized exoplanets in the entire galaxy, or is the data too limited.

 

[contrarian]

Well now, the "synthetic biology" described in your link for "decontaminating" the Martian soil of perchlorates seems like that "energy cycle" that you say is missing from other worlds besides Earth. Why would you be surprised if that biological process already self-initiated on Mars sometime in the distant past?

This is not implied in the least - it is not an energy cycle.

 

[Unclear Engineer]

It is a harvest of energy from the environment. How that energy gets transferred around in an ecosystem depends on how that ecosystem has evolved its chemistry to distribute the energy. Maybe glucose could be involved, or maybe something else. Do you think that Mars has always been missing the "building blocks of life" that keep getting announced in the media as being found in asteroids, etc.? Is it short of some element found in life on Earth?

Your position seems to be that it can't happen unless it happens the way you were taught that it happens on Earth.

Hopefully, not all Ph.D. biochemists as as resistant to considering other possibilities.

 

[contrarian]

Your position seems to be that it can't happen unless it happens the way you were taught that it happens on Earth.

Perhaps you should re-read the article. There is no cycling of energy. It is a one way street to Cl- and O2.

 

[Unclear Engineer]

No cycling intended for the NASA process, except that astronauts will probably be breathing the oxygen and exhaling the CO2, thus using its energy.

But, you have no way of knowing what an ecosystem on Mars would/could do with the resultant oxygen, plus the other elements in the ecosystem that it can react with.

Life on earth evolved (mostly) to use solar photons as the basic energy source, building everything else on that energy input plus available raw materials dissolved in water. So, why could not an ecosystem evolve on Mars to use the solar and galactic energy that comes from ionizing radiation producing perchlorates and the ecosystem harvesting that energy with chemistry dissimilar to the photosynthesis process on Earth? We already think we have found bacteria on Earth that are still alive after being sequestered in solid rock for millions of years, apparently using the energy from ionizing radiation released in the rocks. No photosynthesis available to them. Life without photosynthesis.

And, if life on Earth originated in deep ocean volcanic vents, that also would have been without photosynthesis as the energy source. The dependence on photosynthesis may have developed afterward, and out competed the original process as our ecosystem developed in the Earth environment. Perhaps that same initiator developed differently in a different environment.

We are rapidly coming to the point where we can actually investigate those potentials with real science, not speculation - if we don't screw up the opportunities.

 

[Helio]

Since the distance to these 6 Earth-sized exoplanets is known, as well as all the other exoplanets, is there a guess as the the number of Earth-sized exoplanets in the entire galaxy, or is the data too limited.

There are a lot of unknowns remaining that limit good guesses. The inner regions of galaxies, for instance, are likely problematic for emergent life, though I know I'm changing your question to those in HZs.

The link above reveals a current table showing a total of 54 Earth-like planets in their HZ. But 35 of these are found around M-class stars, which seem to be very active in flare production, so they are more unlikely than not to have much in the way of life forms, IMO.

The G-class (e.g. Sun) are more stable and the HZ is farther away from the star. This is true for the F-class as well, especially the cooler ones (F7-F9), I suspect.

So a conservative stab at it puts us with perhaps 20 Earth-sized exoplanets (0.3 to 2.5x Earth mass) out of the total of about 6000 confirmed exoplanets (7,382 total less 1,372 unclassified). This includes the K, G and F class stars, ignoring the M-class. Thus, ~ 0.3% of all these confirmed exoplanets are Earth-sized in their HZ.

Assuming the stellar class distribution holds for the better HZ of our galaxy, and eliminating, say, 1/2 the total number of stars due to the inner region and other problematic areas, then we might toss-out a number of 100 to 200 million Earth-sized exoplanets. No doubt, there will be factors that chop this down, including a better determination for the HZ boundaries, and the likely importance of an active iron cores for needed magnetic field shielding. Nevertheless, it will take a lot of chopping to make this number insignificant.

New and better scopes are already finding some atmospheric compositions, but it is a daunting task to get their spectrum refined in order to determine the composition. The current S & T has an article showing why this is so. Room temperature water, the article notes, has 320,000 electron transitions, but "5 billion at higher temperatures". Cloud opacity and separating out the stellar lines are major challenges. But they state that they do have the tools they need. Of course, the bigger and better scopes will improve things greatly.

My guess is that advanced Mars, Europa and Callisto in-situ studies will say a lot more.

 

[Unclear Engineer]

Another aspect about the potential ages of civilizations on other star systems is the behavior of the central black hole in their galaxies. If the black hole in the center of the Milky Way was an "Active Galactic Nucleus" at some point in its past, the energy input at Earths distance from the our galactic center would rival our solar input today. What would that mean with respect to life on a planet like Earth?

With the fraction of AGN's apparently decreasing after the initial formations of galaxies, I would expect that the potential for a galaxy to harbor planets capable of producing and sustaining life would increase over time.

So, maybe Earth is not such a late-comer to the potential for sustaining life. Although the solar system is only 4,6 billion years old, how long before that did our galactic center black hole go quiet? Is it really likely that there would be much opportunity for planets to be capable of sustaining life for 10 billion years into the past?