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#1 Re: Life on Mars » Where Should we Send our Rovers to Mars to Look for Early Life? » 2014-02-16 14:12:25

Yes well ExoMars could go to any of the previous landing sites and do new science, because of its capability to dig one meter below the surface, that by itself is enough reason. Even Viking couldn't do that and of course its instruments were cruder also.

Then, with its ability to do sensitive tests for biosignatures, for instance if it could get to Gale Crater (which it can't sadly) it could analyse the same deposits Curiosity anlaysed and see if they have biosignatures of life, in a way that Curiosity can't do.

If not now, eventually our rovers we send now are probably just pioneers for more sophisticated rovers we can send to the same spots later on as technology improves.

I think that they are likely to go to Mawrth Vallis because it's an interesting site to visit and fits their very restrictive requirements, but who knows...

As for human landings on Mars, I think myself that if we do land humans on Mars it won't be for at least quite a few decades, because it's such a complex planet to study. We don't want to send humans to the surface at least until we understand it thoroughly iin its pristine state.

Humans in orbit around Mars could speed this up via telepresence operation of rovers on the surface. But I don't see any role at all in humans on the surface, in spacesuits for the exploration for organics and signs of life, just because there is no way we know that humans could explore Mars in that way without taking a trail of contamination with them wherever they go which would confuse the hugely sensitive instruments we want to send to Mars to look for life there.

Plans to use humans on the surface always had the base in an uninteresting place unlikely to have any traces of organics, far away from any sites of special interest, sending rovers to the more interesting places by remote control to pick up the samples to avoid contaminating them - but it makes much more sense now to do all that from orbit not from the surface, especially as the surface of Mars turns out to be a little more habitable for life than we thought just six years ago. It also costs far less to send humans to orbit, and safer, so a more feasible mission to do at an early stage, once we have safe interplanetary flight.

BTW this is a list of the sites for the first round of candidate selection for Curiosity

http://marsoweb.nas.nasa.gov/landingsit … e_list.pdf

More about the selection process here

http://marsoweb.nas.nasa.gov/landingsites

And voting results:

http://marsoweb.nas.nasa.gov/landingsit … esults.pdf

#2 Life on Mars » Where Should we Send our Rovers to Mars to Look for Early Life? » 2014-02-16 11:36:31

robertwalker
Replies: 14

You might like this article I just did for my science20 blog:

Where Should we Send our Rovers to Mars to Unravel Mystery of Origin of First Living Cells?

It's quite topical as the deadline for submission of candidate sites for ExoMars is 28th February of this year.

This is about early life, which is the target for ExoMars, I plan another similar article later on present day life.

It's a vast multi-disciplinary subject - I did my best - but if any of you spot any errors or omissions do say. Really interested in any comments on it - you can comment on the article itself as well as here.

Also, what are your own favourite places to search for life from Early Mars, Noachian and Hesperian periods?

#3 Re: Terraformation » Venus » 2014-01-22 20:33:57

Hi Tom, just to say thanks, glad you enjoyed the article, and those are interesting ideas.

The extra amounts of sunlight at Venus shouldn't make much difference to the Stanford Torus as they already need a large mirror to reflect sunlight into the habitat (so that the interior is not exposed directly to solar flares and can be shielded), so I think the main difference would be that the mirror can be smaller.

I haven't come across any climate computer type models for terraforming and surely if we do get the ability to do it, will need to do lots of modeling to have any chance of success in any of these big megaproject type schemes. By the time its feasible I expect our computers will be far more powerful also, probably using qubits or maybe something we haven't thought of yet.

Yes, interesting idea that you could use space mirrors to convert the 4 day super-rotation day into something shorter. BTW someone commenting on one of my articles llnked to an interesting project to make breeder solar panels in the sahara desert. This is in 2010.

Sun and sand breed Sahara solar power

And apparently their first solar plant has now become operational, Sahara Solar Breeder programme: Technological platform operational

The idea is to use the power from solar panels to make new solar panels from the desert sands, and so have exponential growth of construction of the panels.

Relevance to Venus, that if you can do the same in space, it might be quite fast to build solar panels and indeed space mirrors also, or whatever else you want to build along with them. Then perhaps these big megaprojects may begin to be feasible - along with great responsibility to make good use of the power we have from this technology.

#4 Re: Terraformation » Venus » 2014-01-12 22:01:24

This is the article I've been working on for some time on Venus Cloud Colonies for my Science20 column

Venus Cloud Colonies - Second Home for Humanity?

#5 Re: Terraformation » Venus » 2014-01-12 22:00:23

Yes, that sounds good to me smile

#6 Re: Terraformation » Venus » 2014-01-10 19:11:36

Yes (at least a likely hypothesis for Tungaska) - but that would be a comet large enough to be worth breaking up before it hits Venus. If you are able to divert comets to hit Venus, would be easy presumably to break them up into tiny chunks say 1 or 2 meters across before they hit the atmosphere. Then you'd hardly notice that anything happened just a nice meteor shower.

I don't know if it is worth while to divert comets to hit Venus, whether that's the best way to deliver water, or if we can somehow make do with the water already there - and I rather think one would do it a bit differently. With advanced technology probably wouldn't be hard to just make lots of parachutes and aeroshells for the fragments of ice, maybe each a few meters across, and parachute them down to wherever they are needed. (Have semi- autonomous machines to make the parachutes, say - or whatever - with only the most minimal of supervision - I think by the time we can divert comets where we like across the solar system and need to make these decisions then will have such devices, 3D printers, etc etc).

But if you did just want to bombard Venus with comets, I think it could be done gently, as gently as you want to, by breaking all the comets into 1 or 2 meter diameter chunks in some way before impact, so it is just experienced as a meteor shower by the hab inhabitants.

#7 Re: Terraformation » Venus » 2014-01-10 14:05:31

Yes that's a good point - and comets are fragile anyway - probably quite easy to break them up before they arrive at Venus, to make them into smaller pieces if you have a large comet. And if you make sure there are no habitats in immediate vicinity of where the comet strikes also...

#8 Re: Terraformation » Venus » 2014-01-10 11:18:39

Yes indeed, that's what I meant, we can build the cloud colonies (planetary protection permitting) - and then study to see what is the best way to terraform after that.

The cloud colonies would be fine for the gentler ways of terraforming. And if we did want to export the atmosphere, is plenty of atmosphere to export without disturbing the colonies.

I do feel a bit cautious here, that we don't have any experience at all of anything like it, and so, maybe there might be some "gotcha" we can't anticipate even about seeding a Venus type planet with cloud colonies. I suppose the main things are

1. Is there a risk we could make the planet less habitable for humans - for Venus I think NO (For Mars, YES)

2. Is there a risk that colonization could get in the way of finding out new and valuable science - for Venus - I think - possible but at present seems unlikely - need to explore it first (to check to see if there are any life forms in the clouds). For Mars - again I think, strong YES.

3. Is there a risk that early colonization could cause problems with ideas to terraform the planet in the future. For Venus - yes possibly - if the future terraforming involves impacting asteroids into a planet inhabited by billions of people in cloud colonies. Also could be an issue if the terraforming involves a careful progression introducing photosynthesizing plants that create oxygen first in great quantities and to keep aerobes well away. But I think less of an issue than for Mars for both those things. For Mars I think there is a high risk that early colonization, just landing humans on the surface with all their microbes, if they start to reproduce and transform the planet in an unplanned way, could thoroughly mess it up for terraforming.

So - I think Venus is far better than Mars - but not totally clear that it is okay - I think needs exploration and research, quite a bit of it, before we set up our first cloud colony on Venus if it is feasible and seems a good thing to do. And I think terraforming Venus also - though much less likely to go wrong perhaps - but you have the same issue as for Mars - that we don't really know much yet about how planets naturally terraform. Earth may be a rare exception or may be common. Also we would be attempting to do in a few thousand years something that on Earth took billions of years, which is a huge speed up. So may not be so easy to guide it to the desired end state as one might think.

E.g. may be many different stable states it could end up in and perhaps many of them might have atmospheres poisonous to humans so may not be as easy as it seems to steer it to the desired goal. I don't think we can really be confident about that right now but in future as our understanding progresses we may be able to be.

And is a long term thing also and it might be you have to keep it going keep doing things to keep it on target - so you have to commit to 1000s of years of terraforming once you get started, and we don't yet have enough experience to know if we can maintain a single technological society with a single long term project for thousands of years. It might well be possible, but we only have a century or so of reasonably high technology to guide us and have no other similar projects to compare it to in scale.

#9 Re: Terraformation » Venus » 2014-01-10 10:57:40

Tom - yes your posts are bringing me around to your way of thinking. Given that Venus has the same composition as the Earth, just in different forms with the CO2 all in the atmosphere, then if one can, makes sense to put it back together as it were in an Earth like form again - if it works.

I also think, that this is far future science we are talking about - terraforming is going to be a centuries long / millennia long project most likely - and by then surely we will know a huge amount more about exoplanets and have supercomputers able to simulate the whole thing in great detail - and must be a very stable long lived society to contemplate a project that would need to be sustained for probably well over a thousand years and most likely thousands of years to completion.

So no hurry to start on it, a delay of a century or two would make hardly any difference compared with the time it would take to complete it, even with extreme mega-engineering, and we may find clever shortcuts and neat ways to do things that would save centuries or thousands of years on the process so certainly good to think it through a lot first for that reason also.

Cloud colonies though, we could start on within a few decades, if it was okay for planetary protection reasons - no life there- and would be reasonably low tec. and sustainable - if detailed studies back up the sketchy ideas we have so far that is.

Though I think the most interesting case is where Venus does have life and so interesting that we decide not a good idea to set up colonies there yet - though disappointing for colonization, would be great for science and biology and understanding of primitive cells and evolution and well compensate for the colonization disappointment.

#10 Re: Terraformation » Venus » 2014-01-10 09:49:45

Okay perhaps ideas like that might work later on - but with present day Venus, even with the long year long night, the night side is almost the same temperature as the day side.

The CO2 near the surface forms a "supercritical fluid" technically, is so dense, is over a tenth of the density of water and transmits heat very efficiently throughout the night side of Venus, same for poles.

https://en.wikipedia.org/wiki/Atmospher … roposphere

In the upper atmosphere above 100 km then you do get a temperature change - the usual thermosphere of Venus on the day side turns into a surprising cryosphere on the night side, extremely low temperatures - but that is well above the cloud habitats level, 50 kms higher.

Another issue with attempts to remove the atmosphere from Venus is that it has so much atmosphere, and the gravity of the planet is strong enough so that unless it is sent into space with enough velocity to leave Venus's orbit and go elsewhere in the solar system, then Venus will just gather all its atmosphere up again, especially heavy gas CO2, over quite short time geologically.

I had the idea - not sure it is original may have read it somewhere else - to freeze the Venus atmosphere and fire it away from Venus and from Venus orbit as dry ice pellets - maybe with some reflective covering added to the pellets to keep the CO2 together as a pellet stop it evaporating - e.g. to Mars if you needed CO2 there or the Moon or wherever in the solar system you needed CO2. Someone else suggested that you could use a Stirling engine, to refrigerate and create dry ice so no need to cool down entire atmosphere and freeze it out. If so that could be a gentle on-going process that gradually removed Venus's atmosphere over thousands of years, lots of these machines, perhaps part of the income of the colony if they can sell the CO2 to other parts of the solar system that need it (at low cost once it is all set up and easy to do).

#11 Re: Terraformation » Venus » 2014-01-09 21:05:51

Sorry got the calc wrong above, and if you stop and give it a moments thought - CO2 gas bubbles of course float in fizzy drinks at normal 1 Atm pressure. The density of CO2 is  0.001977 g/cm3 at 1 bar and 0C. So what does he mean by that quote?

"Buoyancy in air is ultimately a problem for any organism because its density is greater than the air it inhabits. The density of droplets of sulfuric acid, however, is sufficient to keep organisms easily afloat. That means, of course, that organisms are restricted in size to the space available in their airborne aquatic habitat."

Is it just a mistake perhaps? Because sulfuric acid is denser than water, and far denser than CO2.

#12 Re: Terraformation » Venus » 2014-01-09 18:29:33

Okay on extracting water from the sulfuric acid that's the section "Water for Venus". The figures are from 1991 so actual numbers are likely to be wrong. But he says "Sulfuric acid from the clouds will provide water by reactions like H2SO4 + MgSO3 -> MgSO4 + SiO2 + H20 " That's all actually so doesn't say much about it sorry.

Yes the whole thing about the sulfuric acid too concentrated to use wouldn't apply if you are using it within the habitat and diluting it first as you say.

BTW stomach acid has pH 1-2. https://en.wikipedia.org/wiki/Gastric_acid

Acidophiles survive and thrive at PHs below 2. https://en.wikipedia.org/wiki/Acidophile

It says here that the sulfuric acid at the cloud tops would have a pH of 0 and below - similar to battery acid - but that there are some Acidophiles that can live at such low pHs.

http://books.google.co.uk/books?id=b7Xh … ds&f=false

Quite detailed working out of possiblityof life in the Venus Atmosphere by Louis Neal Irwin, and Dirk Schulze-Makuch

I notice says "Buoyancy in air is ultimately a problem for any organism because its density is greater than the air it inhabits. The density of droplets of sulfuric acid, however, is sufficient to keep organisms easily afloat. That means, of course, that organisms are restricted in size to the space available in their airborne aquatic habitat."

Does that mean what it seems to - that sulfuric acid droplets would actually float in 1 bar pressure levels of CO2?? Density of sulfuric acid is 1.84 g/cm³. CO2 has a density of 1.977 g/cm3 at 1 bar and 0C. So yes, seems so, both water and sulfuric acid would float in the Venus atmosphere.

CO2 gas at 1 atm is actually denser than water. If you filled a thin skinned balloon with water it would float in the Venus atmosphere - indeed at the 1 bar cloud colonies level, it would actually float up into the air until it reached the 0.5 bar level.

#13 Re: Terraformation » Venus » 2014-01-09 06:04:55

Just to say, found another article on the cloud cities, 2003 one, by Paul Birch, works out many details, including how to extract water from the sulfuric acid, detailed designs of the cloud colonies - and gradual progression towards terraforming of the Venus surface itself. The cloud colonies section starts on page 163.

http://www.orionsarm.com/fm_store/Terra … uickly.pdf

I found out about it here:
http://nextbigfuture.com/2013/08/cloud- … venus.html

#14 Re: Terraformation » Venus » 2014-01-08 12:42:30

Yes - crashing comets to give the aerostats an easier time sounds a nice idea smile.

With that approach if you want to encourage shading once we have cloud colonies on Venus, then there is Hall's Weather Machine - seems reasonably likely we would have technology to do that once we have floating cloud colonies on Venus smile.

Also remember that even without mega-engineering we have the ability to grow trees and plants which have 90% by weight just from the CO2 plus water in the atmosphere - so long as we can find some process to get the water from the sulfuric acid in a form usable by plants.

Perhaps somehow we can also extract the CO2 to use to make the mirrors for the Hall's weather machine.

Though - all of this is still in the realm of kind of hard sci. fi. I think at present. Nobody has done a properly worked out study of it, while have been a few for Mars (I think those are sketchy also in the extreme though). Would be good if someone were to do a proper engineering type study of Venus cloud colonies.

Anyway here is a link to John Hall's Weather Machine

Youtube videos: http://www.youtube.com/watch?v=Fd63OMosnq0, http://www.youtube.com/watch?v=EOPsczPlzzY

Somewhat critical article about it - http://www.nanotech-now.com/columns/?article=486

#15 Re: Terraformation » Venus » 2014-01-08 10:50:32

Most of our carbon actually is in the form of Calcium Carbonate (limestone). Yes Earth probably has about 90 bars of CO2 as limestone. See Earth's atmosphere before the Dinosaurs

If you could turn the CO2 into limestone - that would work. There would be a risk of the CO2 burning off again - but lime kilns operate at 900C (Lime Kiln - Wikipedia), seems a possibility to me.

Can anyone think of an easy way to turn the CO2 atmosphere into limestone?

You could do it with oceans - but of course no oceans on Venus. Also you still have the problem of the global resurfacing of Venus to think about that happens probably every few hundred million years, no continental drift, is one of those due in the near future? Or should we worry about it if it is a far future thing?

You still also have the problem of the almost year long day. One might decide that it is better to keep the existing atmosphere with the super-rotation for the cloud colonies - to actually rotate Venus faster for shorter days is way beyond the energy levels of human civilization at present.

#16 Re: Terraformation » Venus » 2014-01-08 09:51:31

Yes that was Carl Sagan's idea to split the CO2 and create carbon and oxygen instead. But he didn't realize how dense the atmosphere was or how hot the surface. As Venus is now, then the carbon would just burn and return to the atmosphere. You need some way to get the carbon out of the atmosphere - and also - turn it into some form of rock that will not burn up and return the Carbon to the atmosphere at the surface temperature of 420C.

There is one idea here - to cool down the entire surface with orbital mirrors to below temperature of dry ice, and then cover it with some covering to prevent it from returning to the atmosphere when it warms up, maybe chemically change it? But that is a big mega-engineering project.

Then you still have the long  243 days long day on Venus - so a terraformed Venus wouldn't be that habitable for higher organisms if adapted to and depending on shorter days. (Perhaps if they hibernated every night and woke up in the day?).

While in the cloud tops the super-rotation means that the atmosphere rotates around the surface with a day of about 4 Earth days - which seems reasonable for life to adapt to.

#17 Re: Terraformation » Venus » 2014-01-08 07:15:27

As for fully terraforming Venus, the atmosphere is 93 bars, so  to get down to 3 bars is about as hard as to get down to 1 bar. Somehow send it all into space and it will just gather it up again gravitationally. Make it into a layer of carbon and it will ignite in the atmosphere. Carl Sagan thought it was terraformable originally but changed his mind when the results came in about the atmospheric pressure on the surface.

I think might be possible eventually with megaengineering, e.g. build lots of rail guns to fire the atmosphere of Venus as dry ice into space (and perhaps send it to Mars to help terraform Mars at the same time if that is desired - or anywhere else in the solar system where CO2 is useful) - but that's far future sci. fi. at present levels of knowledge and technology.

You also have the issue that the entire surface of Venus is turned over in a big upheaval every few hundred million years ago (doesn't have continental drift - they stick in one place - and then over a short period of time geologically the entire surface gets turned over). I don't know how long it is until the next such upheaval - is an important thing to think about as it would destroy not just any civilization but probably also wipe out most of the life on the terraformed planet. Probably less of an issue for cloud colonies protected from the volcanism by 92 bars of atmosphere though I imagine would be tough times for them too.

#18 Re: Terraformation » Venus » 2014-01-08 06:57:31

Tom Kalbfus wrote:

I think if we introduced Earth life in the Venusian clouds, it would be like dropping fresh water goldfish in the ocean, I don't think any of the tuna would be threatened by them, the gold fish might make an extra meal for them, as they won't live long in salt water. I don't think we are likely to be able to do anything in the near future that will significantly alter the Venusian climate, by the time we can, we will have and sufficient time to discover and study whatever native life might exist there, and if there is life that is hidden so well that we can't find it even after all that, then too bad. One thing about Venus, is that Geologically it resembles an early Earth before continents began to form. Venus has little water, therefore most of the rock is basaltic, I believe granite can't form without water, so continents as we know them don't exist on Venus, Venus does have highlands though, in the form of pseudo continents Ishtar and Aphrodite, the rest of the globe is dominated by various mountains which would be islands on a terraformed Venus. Venus requires less water than the Earth would to have the same hydro-graphic percentage of its surface covered with water, as its oceans would be less deep than Earths, this probably means blue green algae would flourish in such oceans, and it would probably oxygenate the atmosphere to a greater extent than Earth. There would be a lot of fish in those shallow oceans, plenty of coral reefs eventually too. My sense is it would be easier to do Venus as a tropical planet, shading the area over the equator and some distance to the north and south while letting the poles get a full does of Venusian sunshine, would probably produce a hot steamy planet at the edge of a runaway greenhouse effect. Perhaps this would be what we would want, a global tropic zone, with some relief obtained by climbing the mountains. A 3 bar atmosphere at sea level would probably mean that the tops of the highest mountains would have air that would be quite breathable for us.

Certainly true for most life. The thing is though that we have life able to live in environments on Earth that would be just as lethal to nearly all living organisms. For instance well above 100C, well below freezing, very acid, very alkaline, high levels of metals, high levels of ionizing radiation, extremely dry conditions etc. You also get polyextromephiles that can handle several of those extremes at once. See Extremophile Classificiations

And the thing is also, that microbes retain their adaptations when they are in more clement conditions. So a human habitat, and indeed the human body itself, can host extremophiles and polyextremophiles.

So - is not immediately obvious that Earth life would be unable to survive there, might be, but needs study and simulations.

However the 2006 planetary protection report for Venus seems pretty conclusive

A slight possibility exists that terrestrial organisms could grow on airborne particles near to the
cloud tops of Venus. The problem was discussed at the 1970 COSPAR [Committee on Space Research of the International Council for Science] meeting, and some interest was expressed in investigations of airborne life. Life on Venus is no more than a remote contingency, but the
possibility of contamination by terrestrial organisms must be considered.

Regarding the atmosphere, there are some uncertainties on the likely presence of sufficient
nutrients, a high water activity and the convective rate by which water droplets containing
microorganisms are transported downwards and pyrolyzed at the higher temperatures. The
probability of contaminating the Venus atmosphere was treated in the SSB 1970 summer study;*
in that study, a probability of growth for the atmosphere ≤ 10−6 was recommended and approved
by the Space Science Board (a recommendation which superseded the previous value of Pg
≤ 10−4).

So  that means they think the chance that Terrestrial microbes could grow in the Venusian atmosphere is less than one in a million.

In principle, life in the Venus ocean could have been transported to the clouds and then persisted
there after the point at which life on the surface became impossible and even until the present day. While
this hypothesis overcomes the problems inherent in an origin of life within the clouds, it does not
overcome the formidable problems that would face an organism living in this hostile environment, which
include the following:

• The extremely acidic, dehydrating, and oxidizing environment of the cloud droplet environment, which will lead to the destruction of organic matter;
• The very high energetic cost of recruiting water from concentrated sulfuric acid;
• The high temperatures of the droplets at the cloud base, through which all droplets inevitably cycle;
• The lack of persistence of individual droplets, which have a probable life span of months to,
at most, a few years;
• The loss of nonvolatile elements that fall to the surface of Venus; and
• The absence of biogenic elements that do not have volatile forms (e.g., Na, Mg, K, Ca, Mn,
Fe, and most other metals). Although these elements could be introduced into the atmosphere by volcanic
eruptions and by meteoritic infall, there is no obvious mechanism by which they could become widely distributed among all cloud droplets.

Survival of Earth-Life on Venus
The identification of extremophiles on Earth has expanded knowledge of the physicochemical
limits at which life as we know it can exist. Organisms have been shown to grow at temperatures as high
as 121°C,13 in chronic radiation fluxes of 60 gray/hour,14 in extreme pressures at the bottom of oceans,
and in acidities as extreme as pH 0.15 However, none of these extreme but life-supporting environments
approaches the severity of surface and atmospheric conditions present on Venus. In particular, the
ambient surface and atmospheric conditions on Venus render all currently known extremophilic
phenotypes on Earth irrelevant. Concentrated sulfuric acid is sterilizing for all known organisms. Thus,
genetic and other physiologic determinants necessary for life on Earth could not function on Venus, nor
would biological determinants that evolved on Venus be expected to function on Earth.

The cloud layers in the atmosphere of Venus provide an environment in which the temperature
and pressure are similar to surface conditions on Earth. However, the chemical environment in the
clouds, and specifically in the cloud droplets, is extremely hostile. The droplets are composed of
concentrated (82 to 98 percent) sulfuric acid formed by condensation from the vapor phase. As a result,
free water is not available, and organic compounds would rapidly be destroyed by dehydration and
oxidation. Therefore, any terrestrial organisms having survived the trip to Venus on a spacecraft would
be quickly destroyed. It is not possible to demonstrate conclusively that a spacecraft returning to Earth
after collecting samples of Venus’s surface and atmosphere will not come into contact with hypothetical
aerial life forms and inadvertently carry them back to Earth; however, this has to be considered an
extremely unlikely scenario. At any rate, any life forms that had adapted to living in the extremely acidic
environment of Venus’s cloud layer would not be able to survive in the environmental conditions found
on Earth. No special procedures are warranted beyond those required to maintain the sample integrity necessary for scientific studies of the returned samples.

So that seems conclusive. But that is back in 2006, and I wonder if it needs re-assessment. At the time, there was a dissenting voice on the subject, see Planetary Protection Study Group Mulls Life On Venus:

While agreeing with the report on certain points, Dirk Schulze-Makuch, an associate professor in the Department of Geology at Washington State University in Pullman, Washington remains open-minded that the clouds of Venus may be a safe harbor for microbial life.

Not a task force member, Schulze-Makuch has extensively looked into the Venus-life connection, and also briefed the task force on his research.

"I agree with the task force that the risk of forward and backward contamination is very low," Schulze-Makuch told SPACE.com, "because of the very different living conditions in the Venusian clouds compared to basically all known Earth environments."

However, Schulze-Makuch said he was disappointed that the study group did not suggest any scientific investigation for the explicit purpose of reducing uncertainty with respect to planetary protection issues.

"I wonder if they would come to the same conclusion if we would have confirmation that oceans on the surface of Venus existed for billions of years until fairly recently," Schulze-Makuch said, and that life originated there and later found a refuge in the Venusian atmosphere. Even as hostile conditions gradually increased within the atmosphere, life may have been able to hang on and could still be present in the cloud layers, he suggested.

"For me this is an entirely plausible scenario," Schulze-Makuch added.

Rare niches

As the task force explained, there shouldn't be any significant interaction between putative Venusian cloud microbes and Earth organisms, Schulze-Makuch said. However, there is some uncertainty because most Earth microbes are still unknown and there are some known organisms that come close to living in Venus-like conditions, he suggested.

"We do not know [about] and thus obviously cannot estimate capabilities of any alien organism," Schulze-Makuch said. "Perhaps, if they originated in an earlier Venus ocean they may have still retained the capability to quickly adapt to their earlier environment. Thus, they might be capable of competing in selected, rare niches on Earth, such as volcanic vents."

ESA's Venus Express will not resolve the question of possible Venusian life, Schulze-Makuch said. "But its measurements of water, chemical species, and volcanic activity will shed some light on the viability of our hypothesis of possible microbial life in the Venusian atmosphere."

The chances of an indigenous microbial community floating around in the Venusian atmosphere, Schulze-Makuch concluded, "are not remote but are significant in my mind!"

I think part of it is that planetary protection studies usually use similar ideas to biohazard protection on Earth where a 1 in million chance is thought adequate. But if you fail at planetary protection, that could be a hazard for Earth or for the planet being protected for all future time. So potentially trillions of people in the future could be affected if it goes wrong.

So, I think one should use lower probabilities than 1 in a million. I think a closer parallel is the creation of XNA based life in the laboratory - which has potential to out compete DNA in the wild. The required probability of escape for that, if we ever do it - in one study - was set at one in 10^20. I.e. you have to be pretty certain it can't escape, not just 1 in a million sure. They would do it by such techniques as making it so that it requires ingredients you only find in the laboratory and not in the wild to grow - and to make sure it can't adapt to use normal materials available on the Earth.

Those are "Existential Risk" calculations and personally I think that sample returns for the first time from outside of Earth should use probabilities based on existential risk assessment, and also I think same for contamination of other planets by Earth, that is a personal view - I would require all missions to Mars to be sterilized to Viking levels myself or better, because I'd make the probabilities far more stringent. But that wasn't done and there is a chance we have contaminated Mars, perhaps 1 in 1000 or so, hard to estimate - but reasonable chance we haven't. I think, personal view, again, that for places we haven't yet sent missions to such as Europa especially then we should do far better than the 1 in 10,000 and interestingly some of the scientists in the Europa planetary protection assessment put forward that same view that the standard 1 in 10000 risk of contaminating a planet during the exploratory phase is not strong enough for Europa.

I'm not sure if we need to use such a strong standard for not contaminating the Venus cloud decks. But I think we should proceed with care, and take into account the possibility that we might not know enough to properly assess probabilities yet, and that it may need more research.

Our knowledge moves on and there is always the possibility of e.g. finding new acidophiles that could survive on Venus for instance. I don't think that they actually simulated a Venus atmosphere for instance and tried putting Earth microbes into it to see if any were able to reproduce - it was a purely theoretical study. And our knowledge of the Venus atmosphere isn't that great either, I think we need to know more before we can assess the probabilities well - know enough to be able to simulate it on Earth - if we can do that - and try seeding it with Earth microbes, lots of times in long running experiments to simulate e.g. humans visiting Venus, and none of them grow - then can be reasonably confident that we are not going to contaminate it.

#19 Re: Terraformation » Venus » 2014-01-07 10:26:11

SpaceNut wrote:

Here is the geological clock

http://campus.udayton.edu/~INSS/ThemeEv … dchunk.htm

http://en.wikipedia.org/wiki/History_of_the_Earth

So what was earth 3.5 billion years ago how was the land arranged.

Now was the soup fresh water or salted?

Rather unlike today, hot ocean well above present day boiling point for water, huge tides, probably some small proto continents.

Started off with liquid rock and hundreds of bars pressure of CO2

Then later, very hot oceans over 200C, but also high pressure CO2 atmosphere so kept the water liquid though well above boiling point at present day atmospheric pressure. See Hadean (Wikipedia).

The water was probably more salty than today because a lot of the salt now is in salt deposits result of evaporating oceans - in early Earth not enough continents to make places for the sea to evaporate and deposit salt as rock salt. Probably 1.5 to 2 times as salty as today. See The Hadean-Archaean Environment

Huge tides from the Moon which was much closer than today and shorter day, shorter month.

#20 Re: Terraformation » Venus » 2014-01-07 09:59:15

SpaceNut wrote:

organics have been seen in meteors but it will take one fresh one the sceene of mars to help say that we did not contaminate it once it arrived on earth.

The evidence has been trapped in glass for the most part.
Meteor impact trapped ancient swamp plants in glass

Yes that's exactly one way that organics from ancient Earth or Venus could end up on the Moon. Yes if you return a sample from Mars to Earth is a big issue to make sure you didn't contaminate it. It's a bit of an issue if you don't return the sample but study it on Mars also, studying for traces of life in situ.

The rover that examines the sample must itself be very clean so as not to contaminate the readings. Clean not just of dormant life, but - especially if you are going to send the miniaturized DNA sequencer, also of dead life as well. That's quite a challenge. The normal ways of sterilizing a spacecraft would leave dead microbes on the surface, even heat sterilized like Viking. There's a technique for Mars using supercritical CO2 snow - CO2 in a semi-liquid state  which can get rid of the organics as well and is rather neat as it uses the CO2 in the Mars atmosphere, you'd do that when the spaceship gets to Mars on top of all the other sterilization procedures.

#21 Re: Terraformation » Venus » 2014-01-06 21:25:55

That's interesting smile. Yes I've also heard that RNA is astonishingly hard to derive from early conditions and that some sort of intermediary step is probably needed. Is one of many hypotheses, starting with RNA world of some form, if you've seen the wikipedia article on abiogenesis, gives a good overview of some of the possibilities that have been suggested.

But the intriguing thing is - that if you measure by the number of on redundant nucleotides, log plot - then what we know about life as we trace it back goes only half way back to the origin of life. Also another way of looking at it, the smallest cells we know at about 0.2 microns are far far too complex to have evolved by chance just as they are. So must have been much smaller precursors that presumably were in some sense alive, maybe not reproducing quite as perfectly as present day life, but - some way to get the whole complex machinery of cell reproduction underway simpler than the smallest cells that we know. I saw one estimate that they were probably about 40 nanometers across, the very earliest protocells. Just one idea.

This is the wikipedia article on Abiogenesis if any of you haven't seen it, gives a good idea of the complexity of the subject of the origins of life and how little we know and how many and varied are the ideas about how life might have got started.

#22 Re: Terraformation » Venus » 2014-01-06 21:15:30

SpaceNut wrote:

In the past life question have lead to flame wars so we need to tread lightly.

We do know that the essential elements are available but what are the catylists. First are protiens but then, What is the next key event that will cause a radom RNA strand to form is it as simple as a stirred pot that is left to simmer causing a slow mixing and fragment forming. At what point do we call it life?

Yes I've come across flame wars on this topic in other forums, and will tread lightly - if there are signs of a flame war developing I'll shut up. I got in one truly horrid one early last year actually - didn't realise what was happening until I was right in the middle of it. Learnt from that!

One rule I use now is that if I find myself repeating myself, then that normally means both sides have had their say in an argument and there is probably not that much more to be said at this stage. And the other rule I use is - that in an online conversation - it is okay to just drop out of it when things get heated - and you don't need to keep answering back - can be good to let the other person have the last word smile. And if you have said something that challenges their ideas they need time to think it through anyway, is good to give them some space if there are signs that their views are being challenged in a major way by what you say.

Yes that is a great mystery about abiogenesis. If Venus is the place with XNA then there would probably be very little evidence of how it evolved, much less so than for Earth. I think Mars is by far the most likely planet to have extensive past deposits showing all the details of whatever evolution did happen on Mars. And even if there is no life on Mars and never has been - it had global oceans almost certainly - so will show what happens to a planet with global oceans and organics and the ingredients of life left for a few hundred million years. Should have e.g. protobionts which form easily in the laboratory - things that look like cells but can't reproduce. May have chemical mixtures that are almost life, but not quite, reproduce a bit but imperfectly, or whatever. Anything like that would be fascinating and maybe shed a light on the very distant past.

There is one other source of information though - that could give us insight into not just early Mars but also early Venus and early Earth. That's the debris from the late heavy bombardment. After a big meteorite impact on Earth (say) - then most of the material ends up in the sun, Venus, Mars, also the Moon within a few tens of millions of years. The interesting thing is there - the Moon - this means there should be debris of impacts on early Earth on the Moon. Also there should be debris of impacts on Venus also on the Moon (obviously much less but still should be some). For Mars the best place to look for it is the surface of Phobos. So - may be meteorites, recognizable meteorites or meteorite debris from Earth or Venus on the Moon and especially if buried deep, so not too much damaged by cosmic radiation, then we might find reasonably intact organics, maybe even reasonably intact XNA and DNA in it. Might even find things such as fragments of fossil ammonites on the Moon smile as someone said in one of the news stories on this subject. But unlike on Earth - would be unaltered by anything since then, any organics for instance might still be there - if buried deep enough so also in conditions of extreme cold.

Is a nice idea anyway and a good motivation for sending rovers and astronauts to the Moon along with other reasons for going back there.

#23 Re: Terraformation » Venus » 2014-01-06 21:02:31

Tom Kalbfus wrote:

If Venus can't kill it, I would think it would have little to fear from us. Any life there is is likely to be very simple, little more than a complex chemical reaction really, I don't think it will evolve into anything. Venus' best chance for having complex life forms again, if it ever had them, is us! When the Solar System was young, perhaps one billion years old Venus might have once had oceans, it was likely within the habitable zone then, and since it condensed from the same solar nebula that Earth did, it would likely have had all the chemical ingredients for life. Complex life was a relatively recent phenomenon on Earth, having evolved only within the last one billion years. Perhaps complex life on Venus got an earlier start. If there ever was life on Venus, its days are about numbered, if there are single celled life forms in the cloud droplets of Venus, that is likely all they'll ever be without our interference. I think there are probably a lot of Venus-like planets in the Universe, if they are, the sort of life  forms which might evolve in the cloud tops are probably not unique. Uniqueness comes from complexity. We can study them, but that's no reason not to Terraform Venus, I believe terraforming Venus will take a long time, and if we wipe them out, which seems unlikely of they can survive an environment as tough as Venus, we would be replacing them with something better, we would be an agent of intelligent directed panspermia in terraforming Venus. I think we could make the Universe a more interesting place than it already is.

Yes, just to say, I'm not arguing for the intrinsic merit of the lifeforms on Venus. I have seen that argument, some think we should keep the solar system just as it is in its present state. I think it is an interesting idea, we could do that if we want to, but am not saying we should do that.

Yes especially if they evolved independently then they may be examples of a form of life that is very common in our galaxy (or there again they might not, who knows at this stage).

However - common in our galaxy still means for us, that we would need to travel for thousands of years at sub light speeds to find an example to study. I think we are amazingly lucky to have Mars, and Venus both in our own solar system which were very much like Earth in its early years.

I don't know if either have life, just feel it would be really interesting if they did. In my view make them much more interesting than for their terraforming potential. Just because then they are exoplanets that are interestingly different IN  OUR OWN SOLAR SYSTEM (that emphasis isn't me shouting by the way just to emphasize what for me is the most amazing thing about it if they do happen to have XNA or other independently evolved life).

Yes if there is life there, then it would be highly unlikely to have evolved there as I understand it. We have surprisingly many micro-organisms in the upper atmosphere of Earth. Nothing unique that only lives up there - probably most just gets lifted up there in hurricanes and if the surface of Earth could somehow become inhospitable to life maybe they could no longer survive. But in case of Venus - they take months to float down rather than the days for Earth - enough time perhaps to spread around and reproduce so a tiny percentage but enough get into updrafts again - so microbes that got up into the upper atmosphere of early Venus could possibly still be there. At least some exobiologists have entertained it as a possibility. So, am just saying, is no hurry to colonize Venus cloud cities, and we don't know enough about our solar system.

I think myself that we should explore at present in an open ended way, doing nothing yet that is irreversible like introducing new life to a planet or colliding comets with Mars or building giant mirrors or whatever - but first see what the solar system is like in its pristine state. Though fine to build up lots of future ideas in ones imagination and work out all the details theoretically, and do experiments as far as one can in a safe and reversible way to try to get an idea to see if they would work. But to be prepared to be surprised by things we never expected and to give the scientists plenty of time to find out things and do their work - and be ready to change our plans based on what we find.

#24 Re: Terraformation » Venus » 2014-01-06 15:49:05

SpaceNut wrote:
Tom Kalbfus wrote:

the chance of life on Venus is much less than on Mars, so it a way this makes Venus more suitable for terraforming. if there is life in the clouds, so what? I think life on Earth especially our own, is more valuable than life on Venus, the more complex life forms take precedence over the simpler variety. if there is life on Venus, there is probably life in many other places as well, we shouldn't let that fact prevent us from settling the cosmos. Now if there was intelligent life on Venus, that would be a different story, but I don't think there is, and there is no evidence for any.

Then capture a sample test it and lets move on as life that we know will look alot like what we already know.

It's not so easy as that. First are different layers in the atmosphere, life may not be everywhere so may be some searching needed. Then - our tests may not detect it at first. If it is DNA based we can find it easily - just a tiny fragment of DNA and we can find it by DNA sequencing. But if it is XNA then not so easy to find. (XNA is like DNA but with a different backbone and so XNA microbes probably can't exchange genetic material with DNA based microbes or be detected by DNA sequencers).

Some tests work for both DNA and XNA such as searching for chirality - probably most forms of life will prefer one isomer rather than another - e.g. the XNA probably always (or almost always) spirals the same way so that the transcription machinery can work more easily.

Another good test for XNA is the labelled release where you try to cultivate the life and see if it takes up nutrients and  has chirality preferences again.

But - only 1% of species are cultivable on Earth with us knowing a lot about how to try to cultivate it. And though it is likely that XNA would have chirality preferences, we can't really say it has to. The thing about alien life is that the more different it is from DNA, the more interesting it is, but also the more possibilities that our tests miss it.

So - I think - more than just doing some simple tests such as you might do if searching for life here on Earth. Same also for Mars. You are talking about a scientific process and these typically take months, years, sometimes decades, and sometimes can't be rushed. I think we shouldn't rush the scientists who want to study life on Mars or Venus. There is no deadline and no need for hurry. Instead give them the resources they need, to find out what they want in as much detail as possible - and bear in mind the possibility that they might find interesting life different from Earth life - and that that is the most interesting possibility that we should celebrate. So, give them a chance to find this.

That is I think the view of xenobiologists generally, for instance eight of them wrote a paper for the last decadal review strongly urging against a Mars sample return for these reasons saying we don't have enough understanding of Mars to know what samples are likely to be biologically interesting enough to return, but need to study it in situ, and surface deposits down to a depth of a few meters are sure to be severely degraded by cosmic radiation as well as other processes that seem to remove organics from the surface as an on-going process - and hard to interpret biologically. Their paper was ignored in the Decadal review summing up as far as I can see.

Planetary geologists I think tend to be a little impatient with the exobiologists at times, you can see all the geology plain to view on Mars and Venus, maybe at times a bit hard to appreciate that the situation is not the same for exobiology, where we can't see XNA or microbes from orbit or even have a clue about whether there is any there at all from those wonderful orbital images the planetary geologists use. And is not enough to just take a few samples - until you know where to look, then samples you return to Earth are likely to be uninformative, and they also pose a planetary protection issues as well for Earth, because although they are unlikely to have life in them when we don't know where to look, on the chance that they do ahve life, biological samples of course can reproduce, which purely geological samples can't do. Have written quite a lot about this also on my science20 column.

XNA particularly, if it exists, could present a particularly tough challenge for planetary protection, because of the possibility that either XNA or DNA may be superior to the other - e.g. XNA microbes are hardier, better at metabolizing - or vice versa. If XNA is better then it could wipe out DNA on Earth in the very worst case, or most of it. If DNA is better, it could wipe out most of the XNA on the target planet we want to study - and if both coexist - then still, the microbes based on XNA may behave differently from the previous DNA based microbes in the same ecological niche and so disturb the balance of nature, as well as lead to extinctions, also the microbes based on DNA could lead some of the interesting XNA species to extinction before we have a chance to study them and disturb the cycles again so we can't study the target planet in its pristine state - and also means of course that it is hard to tell what came from Earth in our probes and what was indigenous.

Lots of other contamination issues both ways - needs a fair bit of thought and there have been several studies which all conclude that great care is needed just in case. I think at least not going to sort this out with a simple sample return as the geologists seem to think, but is a long term at least several decades project - which would go more quickly if we have more resources available to study Mars e.g. by telerobotics from orbit around Mars. And if also the instruments developed by the exobiologists and the interesting missions presented to NASA and other space agencies by exobiologists were given higher priority than they are now.

#25 Re: Terraformation » Venus » 2014-01-06 14:48:20

the chance of life on Venus is much less than on Mars, so it a way this makes Venus more suitable for terraforming. if there is life in the clouds, so what? I think life on Earth especially our own, is more valuable than life on Venus, the more complex life forms take precedence over the simpler variety. if there is life on Venus, there is probably life in many other places as well, we shouldn't let that fact prevent us from settling the cosmos. Now if there was intelligent life on Venus, that would be a different story, but I don't think there is, and there is no evidence for any.

I totally agree that the chance of life on Venus is far less than for Mars, and life on Mars seems on the face of it likely to be more interesting, and especially, it would have a long past history which we could trace through all the sediments on Mars, pristine sediments preserved in a deep freeze for hundreds of millions or billions of years.

But - Venus life if it did exist might turn out to be more interesting than expected. For one thing, would be surviving in an environment unlike anything on Earth. Might have special adapatations - e.g. microbes with "wings" to help keep them aloft in the dense atmosphere, or even colonies that form bladders full of hydrogen or oxygen to keep them aloft - or ways of working with the sulfuric acid, or whatever maybe things we haven't thought of. Not saying this is likely. But we don't know yet if there is anything there of interest and there just might be.

More interestingly also, it could have evolved independently of Earth life. Aren't that many places in the solar system where there were early oceans (probably) and also a big influx of energy from solar energy (or radiation from Jupiter in case of Europa).

Just Europa, Mars, and Venus. I leave out Encladus etc because it is a habitat that probably doesn't have so much by way of energy input though life there may also be fascinating if it does exist.

If life is abundant, they may all have life and if life evolves independently easily may each have its own version of XNA. But that's just three big chances of independently evolved XNA, and it might be that only one of them succeeded, and who knows, might be that just by chance, the one with the interesting XNA is Venus. (Could equally be Mars or Europa and could be somewhere unexpected that we haven't thought through properly yet).

With Venus, wouldn't have evolved originally in the cloud tops of course, but retreated to the clouds when the surface became uninhabitable. And because of the difficulty of transfer of life from clouds of Venus back to Earth or from Earth to the cloud tops of Venus at least in present solar system - you could put a case for Venus as quite a good chance for XNA.

Europa perhaps most likely to have XNA, though it also could be related to Earth life DNA as some study showed that in the late heavy bombardment period especially, material from Earth could easily get as far as Europa, big chunks large enough to protect microbes inside from the radiation.

Other way out places like Titan, Triton, or life forms that survive at extremely low temperatures, I remember sci fi story where they used superfluid hydrogen smile. Who knows, very way out but can you really say it is impossible?

But I think Venus is one of the top places where we just possibly might find XNA not related to DNA. If so certainly want to study in pristine state. And if there is life, highly unlikely to be just a single species, surely lots of species of different types in an ecosphere - if only of microbes, still may be complex - and concievably might also be fragile in response to introduction of extremophles if there are any Earth extremophiles that could survive there. A planetary protection work shop a year or two back looked at it and concluded that it was unlikely that Venus cloud top life could live on Earth or vice versa. But it was not conclusive, pending future research - and as we continue to find more and more extra-ordinary extremophiles on Earth, I wonder if they would come to the same conclusion again today.

Now if it was an either or - that the only way Earth life could continue to survive was by colonizing the Venus cloud tops - then it would be reasonable I think, at least on what we know so far, to say that the Earth life is more valuable than some Venusian life form we don't even know if it exists - especially if there were some emergency meaning we have to vacate Earth say.

But we are not in that situation. No imminent danger. Even a nearby gamma ray blast would only damage one side of the Earth and leave it far more habitable than anywhere else in the solar system and with many survivors. Similarly a giant meteorite impact or huge comet suddenly appearing from the Oort cloud headed straight for Earth with not enough time to deflect it - still after either of those disasters, Earth would remain far more habitable than Venus or Mars or anywhere else in the present day solar system.

Then longer term - there are materials in the asteroid belt to make habitats with cosmic radiation shielding with area of a thousand Earths (- as far as I know first worked out in a book by T. A Heppenheimer in the 1970s) and see my Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths). Much more material also further out in the solar system. And a lot of work needed even in Venus cloud tops to make it a second home that can work independently of Earth.

So, though working out ideas and ways of doing it is fine and great, I think no need to hurry things along if there is any chance of finding interesting new things about biology and evolution by a delay of a few decades. It would take centuries anyway for it to make a significant difference, and by then we may mostly be living in free flying space colonies and the idea of colonizing planetary surfaces may have become archaic. And in the remote chance that Venus is much more interesting for xenobiology than it seems, then our descendents may want to keep it in its current pristine state or transform it in some other way we can't currently imagine.

I agree though - that on the face of it anyway - Venus seems an unlikely place for life even in the cloud tops. Compared with Mars and Europa - is a place likely to have minimal planetary protection implications. Just think, though that seems likely, yet we shouldn't conclude definitely that it is okay until we have got some ground truth from more direct studies of the Venus atmosphere e.g. with floating probes equipped with biosignature detectors, miniaturized DNA sequencers (in case it is related to Earth life), advanced label release, electron microscopes etc - all things we can now miniaturize enough to put onto a spaceship in the very near future. some of these instruments especially the sensitive biodetectors for Mars are going to fly as soon as 2018, and perhaps could be adapted to Venus cloud tops?

It would be so amazingly interesting, and the best result for humanity and understanding of biology and evolution, if Venus cloud tops or Mars or Europa or all of them were host to interestingly different XNA, or other life forms unlike Earth life to be worth extended study - easily offsetting the inconvenience that you need to delay ideas for colonization and terraforming, in my view.

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