President Obama, if you love science,
 Please protect Mars life from contamination from Earth
For Future of Exobiology - MOON FIRST

President Obama has just taken the unusual step of publishing an Op-Ed article for CNN "America will take the giant leap to Mars". It promotes his vision for humans on the Mars surface in the 2030s. The video at the head of the article highlights his love of science. But what would humans landing or crashing on Mars do to the science he so loves? Unlike a robotic lander, a human occupied spacecraft can't be sterilized of its trillions of Earth microbes, and a crash of a human crewed spacecraft on the surface would end planetary protection for Mars. It's easy to find life if you bring it yourself, but what an anticlimax that would be to all our years of exploring the planet! Here is another video with clips to show his love of science.

President Obama presenting John Glenn with the medal of freedom. He was the first American astronaut to orbit in space.

(You can also read this article as part of my new book "If You Love Science, Don't Rush To Land Astronauts with Trillions Of Microbes On Mars", available on kindle, and also to read for free online)

I never thought of planetary protection for human missions to Mars myself, until a few years back. So, I can understand from my own experience how it is possible to simultaneously agree that we need it for robots, to be keen on science, and yet at the same time, to forget about it as soon as humans are mentioned. Robots can be sterilized. Humans have trillions of microbes on our skin, in our gut etc, and sadly, we can't be sterilized of them. Nor can we replace them all with microbes unable to survive on Mars. Any attempt to remove all our microbes would kill us.

We may be on the point of making the next major discovery in biology. What we discover there could be so major that historians of the future mark out three significant points in biology

Of course we have no idea what those discoveries will be. We have found many possible habitats for life on Mars, but we have not yet been able to send any spacecraft up close to look at them. Indeed Curiosity may be not far from some of those. If they are indeed possible habitats, it's not sufficiently well sterilized to look at them close up, and at best, it may be able to observe them from a distance of several kilometers.

Curiosity at a drill site called Okoruso on the lower slopes of Mount Sharp

(Note, like most images from Mars, it is colour adjusted - to human eyes the sky is more of a butterscotch than pink in colour, this image uses the raw images. Stitched together from the MAHLI images here)

It is just a few kilometers away from some dark streaks that might possibly be marks created by salty brines that flow just below the surface. See the red spots on this image in a Nature article of possible Recurring Slope Lineae (RSLs) near to Curiosity's projected path up Mount Sharp. Are they indeed RSLs, and are they habitable to Earth microbes if they are?

Frustratingly, the only photographs we have of confirmed RSLs are from an orbiter that approaches Mars closely during the local afternoon. That's the worst time of day to try to detect  these seeps of salty brine which probably flow in the early morning. Still, through ingenious detective work, scientists got the answer at last, or are pretty sure anyway, see  Why Are Hydrated Salts A Slam Dunk Case For Flowing Water On Mars? And What Next? The big questions about them now are: "Are these seeps are inhabitable?", and if so, "Is there any life there?".

We don't know if the streaks on Mount Sharp are RSLs. If they are, and if they are habitable, Curiosity is not sufficiently sterilized to approach one of these sites to find out more. Hopefully it will be able to take photographs from a distance of several kilometers, which may help. See NASA weights use of rover to age potential Mars water sites. Also hear Dr. Ashwin Vasavada talking about them on David Livingston's the SpaceShow.

Discoveries of this sort are what I've called a "super positive outcome". There is no risk to humans from introducing Earth life to Mars, so it's not covered by the precautionary principle. But there is a risk of losing something wonderful and precious. Just to give an idea of what we might find, let's venture into the realms of speculation.

What we discover there could include any of:

  • Early life, e.g. tiny RNA world microbes without DNA or proteins. There are many ideas for early life that could perhaps still exist there, though extinct on Earth. These could fill in the huge gap between the organics and cell like structures resembling cells that turn up in laboratory experiments, and the immense complexity of modern life. One idea is an RNA world cell with no proteins, or ribosomes either, instead using RNA sliced into pieces and recombined to make a ribozyme, a tinier distant cousin of the ribosome. This is possible in theory, and some have suggested that present day Earth might have a "shadow biosphere" consisting of RNA world cells, but this has never been confirmed.Maybe we can find RNA world cells on Mars instead?

    There are many other ideas for early life that could perhaps still exist there, though extinct on Earth, including the so called autopoetic cells that replicate just by producing daughter cells with a similar mix of chemicals when they get large, with no genetic code to regulate the process.
  • Unrelated life, perhaps based on some form of XNA (Xeno Nucleic Acid) instead of DNA. This would be the most amazing discovery of all. It would lift biology into a new dimension, show how life can exist based on completely different principles from DNA based life.

    There are many alternatives to DNA and RNA. RNA and DNA are both particularly fragile, DNA especially and hard to form naturally, need the environoment of the cell or special conditions to keep them stable. RNA is more stable when it is very cold for instance, and ribose in its backbone is stabilized by the presence of borates, one of the points in favour of an origin on Mars. Some of the others are more robust and some think we may have started with a PNA world for instance as it is far more robust than RNA and forms more easily.

    Other ideas for early life include TNA world, or a molecule that's a hodgepodge mixing different backbones in the same molecule with non heritable variations in backbone structure (or a whole alphabet soup" of other possible precursors such as HNA, PNA, TNA or GNA - Hextose, Peptide, Therose or Glycol NA).

    The interior of a cell is so complex it's been compared to an entire ecosystem. So life based on different principles could be as revolutionary for biology as discovering a coral reef for your first time, when the only ecosystem you knew about before is the African Savannah. I make this analogy here: "Super Positive" Outcomes For Search For Life In Hidden Extra Terrestrial Oceans Of Europa And Enceladus
  • Life that is based on novel new principles that we haven't thought of yet. For instance, what if other life doesn't use a helix? Suppose for instance that the life used a sheet like two dimensional structure, planar rather than linear, and replication happened by a second layer forming on top of the original sheet?

    Or could it even be a 3D informational polymer?  Is there any approach that avoids the need to uncoil to read it? We can do this mechanically through laser scanning, in prototypes for future memory devices, so the idea is not so far fetched as to be totally impossible.

    This is just fun speculation at present. But suppose that you are an ET biologist and your life uses 2D sheets to replicate - would you not find the idea of a helical structure that has to uncoil and unzip to replicate implausible and unlikely too?
     
  • Life that has evolved further than Earth life. Mars has had such harsh conditions in the early solar system, alternating ice and more habitable phases. It's also been subject to strong ionizing radiation, extremes of cold, and near vacuum atmosphere. Some think that we have multicellular life on Earth as a result of a snowball Earth phase. If that's true, you could make a case for Mars life to be more highly evolved than Earth life - more complex, more robust cells, with more non redundant nucleotides, and more capabilities than Earth life, maybe even totally novel capabilities never explored here, even if it is just single cell life.

    Present day Mars probably only has microbes, or perhaps lichens, if it is fair to make a comparison with similarly harsh environments on Earth. But the harsh environment may mean it evolved further on Mars than on Earth. Or could mean it didn't get as far and is an early form of life. It's hard to say in advance which way this would go 
     
  • Life with a capability Earth life doesn't have, e.g. a new form of photosynthesis.

    We have     three ways of doing photosynthesis on Earth - broadly speaking. 

    Green sulfur bacteria, which use light to convert sulfides to sulfur, which is then often oxidized to sulfur dioxide
    Normal photosynthesis which splits water to make oxygen, also taking up carbon dioxide in the process. (basic equation 6CO2 + 12 H2O → C6H12O6 + 6O2  + 6 H2O where the oxygen atoms in bold are the same ones on both sides of the equation - see Plants don't convert CO2 into O2, and Notes on lamission.edu)
    The photosynthesis of the haloarchaea which works similarly to the receptors at the back of our eyes, based on a "proton pump" which moves hydrogen ions across a membrane out of the cell using bacteriorhodopsin similar to the rhodopsin in our eyes, with no byproducts such as sulfur or oxygen, just creates energy directly from the proton gradient.

    ET microbes might well use some fourth form of photosynthesis that has never been explored on Earth.
     
  • Life similar to Earth life in most respects, would raise many questions. How has it evolved in such a different environment, since last transfer from Earth, surely at least tens of millions of years ago. How did it get there? We can test the theory of panspermia, find out in practice how easy it is for life to be transferred to another planet.
     
  • No life but with organics, and all the ingredients for life but no life. This may seem boring, but it would tell us a lot about how hard it is for it to evolve on a planet, and about the paths it follows on the way to life. If not life itself, there has to be some complex organic chemistry going on, and cell like structures surely form, as that happens even in short term laboratory experiments. So how far did it get and what exactly happens on a world similar to Earth in many ways (especially in the early solar system), but without life?

    Also, on Earth it's impossible to study uninhabited habitats, except for a very short time after a volcanic eruption. Life appears rapidly on any uninhabited habitat here. On Mars, we might have the opportunity to study uninhabited habitats on a planet that hasn't been inhabited for billions of years. This could help us to understand exoplanets and the origin of life and maybe find out that life is harder to evolve than we thought. It can also help to disentangle effects of life and non life processes on Earth.
     
  • Some major unexpected discovery that nobody currently is likely to predict.

It might seem hard to get excited about microbes - but think of them as microbe ETs, and perhaps you may see them in a different light. As minute emissaries from another biological cosmos, tiny beings with a potentially totally different biochemistry.


This shows how DNA makes protein. Notice how complex the process is.



It happens in exactly the same way in every single cell of every single Earth creature. Imagine what it would be like to find a cell that does it differently?

I've heard it said that the interior of a cell is so complex, with its million different chemicals, and elaborate structures and processes, that to researchers studying how cells work, it seems as complex as an entire ecosystem. So, what about using actual ecosystems as an analogy here?

Imagine that you have been brought up in the African savannah - with its grasses and trees and elephants and antelopes. You've never seen a marsh or a forest, or a beach. All your life you've lived in a hut in the African Savannah, never traveled more than a few miles from your hut, and that's the only thing you've ever known.

View of Ngorongoro from Inside the Crater

Then one day someone takes you to the sea shore, with its fish, shellfish, seaweeds, and sea anemones, and perhaps they take you on a dive to see a coral reef.

A Blue Starfish (Linckia laevigata) resting on hard Acropora coral. Lighthouse, Ribbon Reefs, Great Barrier Reef. Photo by Richard Ling

The interior of a cell of XNA based life could be as different from the interior of a cell of DNA based life as the African Savannah is different from a coral reef. And imagine the new perspectives we might get if we can study it.

The search for life is the main motive for all the missions to Mars to date. Look at how excitedly NASA reports yet another discovery of possible past or present water on Mars. And what a huge anticlimax it would be to get there, find life, it's headline news in all the papers, and then follows the anticlimactic announcement that it was just life that was brought there by the human explorers themselves! Then would follow speculation and questions about whether there was any native Mars life there before the Earth microbes got there, maybe never answered definitively. Or we find evidence that there was some native life that went extinct in the very decade that humans landed there, an ecosystem of many Mars microbes interacting, now gone. Or we find some present day indigenous life, but it is already getting overwhelmed by microbes from Earth, and there follows a rush to try to find it in the many different potential habitats on Mars before it goes extinct.

I think the example of an early form of life is the easiest to use here to show how vulnerable native Mars life could be, potentially. It could be some form of life that was been made extinct on Earth billions of years ago, RNA world life say. It might not last for long after more modern life from Earth gets to Mars.

For more about this see my article Will We Meet ET Microbes On Mars? Why We Should Care Deeply About Them - Like Tigers

So now, what happens if Elon Musk sends 100 colonists to Mars and then the spacecraft crashes? Out of thirteen attempted landings on Mars (now including Schiaperelli) only seven have succeeded, two soft landed but with no significant data returned, and four have crashed.

Schiaperelli crash site on Mars. The lower white dot is thought to be the parachute and the upper dark dot, the crash site for the lander itself. Mars is the toughest place to land in the inner solar system.

Out of thirteen landers that have attempted to land on the surface of Mars itself, only seven have been successful, with one partial success Mars 3. There have been four crashes

Successes: Viking 1 and 2, Pathfinder, Phoenix, Spirit, Opportunity, Curiosity.
Crashes: Mars 2, Mars Polar Lander, Deep Space 2 (same mission as MPL but separate landing) and Schiaperelli
Soft landing but no data or hardly any data , Beagle 2 and Mars 3

Since the focus here is on the risk of a crash on the surface, I ignore missions that never got to Mars.

Even NASA has had crashes on Mars with its Mars Polar Lander and Deep Space 2 in 1999, which entered the Mars atmosphere independently and both crashed for different reasons. Since then, they have had a string of successes, with Phoenix, Spirit, Opportunity and Curiosity.

However, impressive though that is, you can get a string of four successes easily even if the chance was only 50/50 of success each time. The chance of four successes in a row is then 1 in 16, or a 6.25% chance. This could mean that NASA is better at landing on Mars than ESA. But the statistical significance is not quite 2 sigma, not nearly good enough for scientific validation that they are statistically better than ESA and Russia. ESA did everything right, including a radar to measure the distance to the ground. The ESA has many deep space successes: Mars Express, Rosetta, the Philae Lander was a partial success and was attempting something never done before, Ulyssees,  the Huygens Titan probe, Venus Express.

With Curiosity's seven minutes of terror, the mission controllers really didn't know if it would land safely or not. Even Curiosity 2020 is not guaranteed to land successfully. We might have other reasons to suppose it has a good chance of success, but just based on the statistics, the chance of a successful landing could easily be 50/50 or lower. So similarly, if you got four successful missions using the same system as is needed for humans to Mars in a row, which would count as an excellent record for unmanned missions, it would not give much assurance that your chance of success for the next landing is better than 50 / 50. You'd need other reasons for your confidence if you thought a crash was unlikely.

Following a precedent set by Carl Sagan, planetary protection discussions are often based on the idea that the risk of contamination should be less than 1 in 10,000 per mission (ideally of course the risk should be zero but we don't have that capability at present).

Elon Musk himself warns that there is a high risk of death for the first colonists to go to Mars. With his supersonic retropropulsion proposal, his rockets have to streak across the landscape, so close to the surface that they can't land on mountainous areas on Mars. (Robert Manning talks about supersonic retropropulsion and challenges associated with landing large payloads on Mars here). For more about why it is so hard to land there safely, see my Why do Spacecraft crash on Mars?

Debris from Columbia - broken into tiny pieces by the crash.

What if this happens on Mars, with the debris spread over the surface? What happens when the global dust storms strike, and particles of dust, small debris and organic materials from the crash get carried throughout Mars?

Microbes would certainly survive such a crash. Indeed hundreds of worms, much more fragile than hardy microbes, survived the Columbia crash. 

One of the Caenorhabditis elegans worms, size of a pin head, which survived the Columbia disaster in an experiment held in six canisters, each containing eight petri dishes.

For more about this see my Why Do Spacecraft Like ESA's Schiaperelli Crash On Mars So Easily?

This surely would be the end of any chance of protecting Mars from Earth life. It is something we can never reverse, once there are hardy spores of Earth life in their countless billions scattered in the dust storms on Mars.

Dust storm on Mars shown in right hand image. After a crash of a human occupied spaceship on Mars, numerous hardy microbe spores would be scattered in the dust storm season, every two Earth years. The effects would be irreversible, and we would have to say that it is no longer possible to protect Mars from Earth microbes.

After that, any experiment that finds present day life on Mars would have to start with the assumption that it might be Earth life introduced as a result of the crash.

NASA's planetary protection office agrees, but say that their job is to work out if the planet can be protected in the case of a successful human landing. So, they don't consider crashes of human occupied ships in their assessments. That is for NASA to look at, at a later stage. Also, they no longer aim for reversible biological exploration of Mars in the case of a human landing.

In their list of knowledge gaps for human extraterrestrial missions, they cover such things as leaks of microbes from spacesuits in EVA, transport of microbes in the dust storms. But there is no mention at all of the effects of a crash of a human occupied spaceship anywhere in the list. They have to assume a 100% success rate for humans landing on Mars as without that assumption they would not be able to recommend any measures that could protect Mars from Earth life, even temporarily.

Their approach is that we will have a small precious window to find out as much as we can about Mars before humans introduce Earth life there by landing on the surface. Emily Lakdawalla, planetary geologist who often reports for the Planetary Society, expresses a similar sentiment in this article

"NASA recognizes that the potential for contamination is a problem, so there is a Planetary Protection Office that is specifically charged with overseeing how missions avoid contaminating Mars with Earth biota. There are two main approaches. One approach is to sterilize the heck out of anything that will actually be touching Mars. That's why Curiosity's wheels were specially wrapped throughout its final assembly, and why it was such a scandal that the drill bits were handled after sterilization. The other approach is to avoid landing in any location where you might encounter -- or accidentally create, should you crash -- a present-day habitable environment where Earth microbes could thrive. For instance, current rules prohibit NASA from targeting a mission containing a hot radioisotope thermoelectric generator (such as Mars 2020) anywhere near a place where a failed landing might place that generator close enough to subsurface ice that the heat of the decaying plutonium could melt it.

"But all bets are off once you send humans to Mars. There is absolutely no way to make a human clean of microbes. We are filthy with microbes, thousands and thousands of different species. We continuously shed them through every pore, every orifice, with every exhalation, and from every surface. True, almost all of our microscopic friends would fail to thrive in the radiation-baked, intensely cold and arid Martian environment. But life is incredibly tenacious. Sooner or later, humans will get to Mars; even if they die in the attempt, some of their microbial passengers will survive even the worst crash. Once we've put humans on the surface, alive or dead, it becomes much, much harder to identify native Martian life.

"This is one of many reasons I'm glad that The Planetary Society is advocating an orbit-first approach to human exploration. If we keep our filthy meatbag bodies in space and tele-operate sterile robots on the surface, we'll avoid irreversible contamination of Mars -- and obfuscation of the answer to the question of whether we're alone in the solar system -- for a little while longer. Maybe just long enough for robots to taste Martian water or discover Martian life."

Cassie Conley has also said she thinks Elon Musks' ideas have planetary protection issues, in an interview just before his big announcement here: Cassie Conley. Going to Mars Could Mess Up the Hunt for Alien Life

There are no detailed guidelines yet for humans to Mars. These would be made by the international COSPAR committee which meets every two years, and all of their discussions to date have ended without any firm recommendations, saying that more information is needed.

I think however that the idea to exploit a brief window of opportunity of a few years before the first human landings or colonization attempts is just not good enough. We simply shouldn't risk destroying such a precious opportunity to make scientific discoveries, on the basis of ignorance.

Here is a quote from When Biospheres Collide

"One of the most reliable ways to reduce the risk of forward contamination during visits to extraterrestrial bodies is to make those visits only with robotic spacecraft. Sending a person to Mars would be, for some observers, more exciting. .... But in the view of much of the space science community, robotic missions are the way to accomplish the maximum amount of scientific inquiry since valuable fuel and shipboard power do not have to be expended ... to keep a human crew alive and healthy. And very important to planetary protection goals, robotic craft can be thoroughly sterilized, while humans cannot. Such a difference can be critical in protecting sensitive targets, such as the special regions of Mars, from forward contamination.

"Perhaps a change in the public's perspective as to just what today's robotic missions really are would be helpful in deciding what types of missions are important to implement. .... The spacecraft instruments, in other words, are becoming more like collective sense organs for humankind. Thus, according to Johnson, when NASA conducts it's so-called robotic missions, people all around the world are really "all standing on the bridge of Starship Enterprise". The question must thus be asked, when, if ever, is it necessary for the good of humankind to send people rather than increasingly sophisticated robots to explore other worlds"

For all we know at present, we might have to travel light years to other star systems to find another planet like Mars to study in its original state without Earth microbes, if we can find one at all. Look at all the mistakes we have made in the past - extinct dodos and passenger pigeons, introducing rabbits to Australia in order to make settlers "feel at home", also introducing feral cats, rats, and making many species extinct, through ignorance of the consequences of our actions. Right now species in the Amazon rainforest are becoming extinct before we know what we have lost.

Martha, last of the passenger pigeons, which once formed huge flock,s and with a population of three to five billion, may have been the most numerous birds on the Earth before they became extinct. Their accidental extinction was one of mankind's many mistakes, and drew attention to the possibility of making even a numerous species extinct.

We haven't got any experience of introducing life to other planets, and so don't have object lessons like this to warn us of what might happen. Science fiction movies like Star Trek may give the impression that we can land humans on any planet in the galaxy, and the microbes they bring with them will have no consequences on the local ecology. However, these are the product of script writers' imaginations, by writers who themselves have no experience of what would actually happen in that situation, and are not predictions of what would happen in practice.

We have made many mistakes already on Earth. Introducing Earth microbes to Mars could easily turn out to be one of our worst ones ever.

POSITIVE VERSION OF PRECAUTIONARY PRINCIPLE

I think we need a positive version of the precautionary principle, something like this (I'm no lawyer, I've just taken the phrasing of the Wingspread conference on the precautionary principle, 1998 and changed harmful to "superpositive" and made other similar changes):

"We believe that human activities have potential to lead to discoveries of such positive value, "superpositive outcomes" that new principles for conducting human activities are necessary to ensure that this potential is not destroyed.

"While we realize that the future can't be predicted, people must proceed more carefully than has been the case in recent history. Corporations, government entities, organizations, communities, scientists and other individuals must adopt a precautionary approach to all human endeavors. 

"Therefore, it is necessary to implement the Precautionary Principle for superpositive outcomes: When an activity may lead to a superpositive outcome, precautionary measures should be taken to keep this possibility open even if some cause and effect relationships are not fully established scientifically. 

"In this context the proponent of an activity, rather than the public, should bear the burden of proof. 

"The process of applying the Precautionary Principle must be open, informed and democratic and must include potentially affected parties. It must also involve an examination of the full range of alternatives, including no action."

This could also be applied to other superpositive outcomes such as potential for new medicines and knowledge from tropical jungles. We have no idea what knowledge has already been lost through deforestation and extinction of species that scientists have never had an opportunity to study.

However, I think it applies in an especially overwhelming way to this potential of discovery of novel lifeforms on other planets.

So in this case, for Mars, we do not know what the chance is of a superpositive outcome, such as discovery of a novel exobiology. It is possible that Mars is so unique that we would have to travel to a planet around another star to make the same or similar discoveries there. Indeed, there might also be nothing like it for tens or hundreds of light years in all directions (e.g. if the discovery is related to unique conditions that prevailed in the nebula that gave birth to our solar system).

There is no way to prove that this is the case, of course. But we shouldn't just proceed on a basis of not knowing what the risks are.

Advocates of colonization of Mars project a sense of urgency, that we have to send humans to Mars as quickly as possible to protect our species. Of course their impatience is understandable, as this is something that they have hoped for, for decades. But there is no urgency to send humans there. We are amongst the least endangered of all higher animals on Earth. We could survive events that made the dinosaurs extinct with our mammalian physiology, our omnivore capability to survive on a diverse range of foodstuffs, and the simplest of technology such as ability to make clothes, and boats, to use simple tools, and to cultivate plants, farm animals and fish. We can take our time, and it's not a race to see who gets there first. I'll go into this in detail in Wait, Let's Not Rush To Be Multiplanetary Or Interstellar

The opinion of experts on whether there are habitats for life on Mars and whether there is present day indigenous life there spans the entire range from 0% to 100%. Views on the possibility of present day life on or near the surface.

I argue that it shouldn't be up to astrobiologists to prove that introduced Earth microbes will impact on Mars based just on what we know so far at the time of a human landing attempt. That is obviously impossible to do when we haven't yet sent a rover to examine any of the possible habitats on the ground, and especially if the lions share of funding is used to establish humans on the Mars surface rather than to explore the planet in a biologically reversible way first.

Zubrin has argued that because of meteorite transfer, life on Mars is so similar to Earth life that introducing Earth microbes will have no effect on it. Alberto Fairén and Dirk Schulze-Makuch also suggested that we no longer need to protect Mars, using Zubrin's meteorite transfer argument essentially, in "The Over Protection of Mars". This was rebutted in a follow up article "Appropriate Protection of Mars", in Nature by the current and previous planetary protection officers Catherine Conley and John Rummel. The two papers are summarized in The Overprotection of Mars? published in NASA's online astrobiology magazine,

If Mars and Earth were as similar as this at a microbial level, it would be so remarkable that I think most astrobiologists would want to study the situation on Mars to find out how this happened, before confusing it by introducing more Earth life. The most recent time that Earth microbes could get to Mars is perhaps at the time of the impact that formed the Chicxulub crater, 66 million years ago, and a more likely time for it to happen is in the early solar system, over three billion years ago, soon after formation of the Moon. Also, most Earth lifeforms, including lichens, and many microbes able to survive on Mars, would not be able to make the journey. How likely is it that both planets have the same microbes, after millions, or even billions of years of separate evolution in such different conditions as Earth and Mars, and with only some of the species shared via meteorite impacts, if any? I cover this later in How a human spaceship could bring microbes to Mars - Zubrin's arguments examined

If we have a precautionary principle for super positive outcomes, it is then up to Zubrin and Dirk Schulze-Makuch et al to prove this hypothesis, and not up to the astrobiologists who think we should protect Mars to disprove it. To establish either view is clearly impossible when we haven't yet had an opportunity to do the most basic of preliminary biological surveys of Mars.

So it is a similar situation to the precautionary principle, but in a positive sense. And just as for the precautionary principle, we have to consider the full range of alternatives, including no action, which in this case means that we should consider not sending humans to the Mars surface.

Instead of sending humans as rapidly as possible to Mars, the place in the inner solar system most vulnerable to our microbes, let's send humans back to the Moon.The Moon is the safest place to explore, for its own sake, as a gateway to our solar system. We can have lifeboats there, fueled and with provisions for the crew for two days, ready to take everyone back to Earth in an emergency.

Coast Guard Lifeboat practicing in the big surf just outside and south of the Morro Bay harbor mouth CA. Photo © 2012 “Mike” Michael L. Baird
We can equip a habitat on the Moon with lifeboats each with provisions for two days sufficient to get the entire crew back to Earth in an emergency. 

For a type I or type II Hohmann transfer orbit to Mars, then the crew are on their own, even one hour after their spaceship sets off for Mars. It won't have enough delta v to reverse course and return to Earth at that point and there is no other way to get the crew back quickly with present day technology either; indeed, they would have to come back via Mars.

This makes the Moon far far safer to explore than Mars for human crew in the near future.

For that reason, though I'd dearly love to see humans orbit Mars, I think the time isn't right for it yet. We need to do multi-year explorations closer to home before we know that we have the technology and that it's reliable. The ISS is not at this stage of readiness because it is designed for LEO rather than interplanetary missions and it needs to be replenished every few months. The ISS has also had issues with its life support system in the past ,which were not serious mainly because it was easy to resupply it from Earth with emergency oxygen.

Getting the mass there is not the main problem; keeping the crew alive is. Nowadays we can keep humans alive in submarines for years on end, if necessary, only resurfacing to take on food, but they are nuclear reactor powered and work by pumping seawater on board and turning it to fresh water and oxygen.

We need a similar level of reliability to get to Mars, but it has to be tested in space, not on Earth, in several shakeout cruises. Unlike nuclear submarines, there won't be any option for the crew to surface in an emergency. They are committed to the vacuum of space surrounding them for two years or more (or 500 days for the shorter round trip via Venus after Mars). 

This I think is just not something we can do safely at our present stage of technology. It is probably within reach in a decade or two, but we aren't there quite yet. We have to proceed more slowly. And the Moon is the obvious target here.

Imagine if the early Antarctic explorers had been content to just set foot on the continent and then said "Been there, done that, let's find somewhere else to explore". That's what it is like to go to the Moon in the 1960s through to the 1970s, and then never go back again.

The Moon is both far more resource rich, and far more interesting than anyone realized just a decade ago, with ice at the poles, possibly large quantities of precious metals like platinum from iron meteorite impacts, possibly vast caves below the surface, so large that you can fit the city of Philadelphia inside with plenty of room to spare, and many mysteries to solve. It must have meteorite fragments from the inner solar system, from Earth, Venus, Mars, but unaltered by any geological processes, just sitting there buried in the ice at the poles for billions of years. There is much there that is unknown and to discover, and impossible or hard to detect from orbit (for more about this see science surprises).

Yet, Mars looks so much more habitable than the Moon in the photographs which are digitally enhanced to increase the amount of blue, and to brighten them, to make it easier for geologists to identify the rocks. These press photos are often so transformed the skies are blue rather than the natural grayish brown. I think this is part of the reason why so many people are keen to go there, that it looks so Earth-like in the press photos.

This is a colour enhanced Mars image as you would see it in most press photos - enhanced for the purposes of geologists:

This is what Mars would look like to a typical smartphone camera. It's the raw image from Curiosity (these photos are of Mount Sharp):

Photos from here

Sometimes the sky in press photos of the Mars surface is more of a salmon, peach or pink colour:

Curiosity self portrait at 'Murray Buttes'

This also is colour adjusted. You can tell because the brightest colours on Curiosity are pure white, so it has to be white balanced.

This is one of the raw images used to make it

More raw images used to make the image here - taken with the MAHLI camera at the end of the robotic arm.

This is a recent non colour adjusted image of Mars

Farewell to Murray Buttes.

As you see the natural sky colour is much more of a brown than a red. It's often described as "butterscotch".

WHAT IF THE MOON HAD BLUE SKIES

I found, when writing Case for Moon First, that the Moon often beats Mars for in situ resources and habitability comparisons. 

So, I wondered, what if we gave the Moon photos blue skies too, like many of the Mars press photos? It's easy to do because the surface is already lit up just as it would be for a sunny day on Earth. We don't need to do anything else, just colour the sky blue instead of black, and it looks Earth-like already. I was amazed at what a difference such a simple change makes to the feel of the scene. You can read it as if illuminated on a sunny day, which is indeed what it was like for the Apollo astronauts. 

Original here Apollo 17 at Shorty Crater - blue sky from here

Astronaut Eugene Cernan walks toward the Lunar Roving Vehicle during an EVA for Apollo 17, the last mission to land on the Moon - with the black sky replaced by a blue sky.

Original here, sky from here

For more examples, see my article: What If The Moon Had Blue Skies? One Small Change To Apollo Photos

These photos are not meant as a suggestion that we terraform the Moon though Gregory Benford and Geoffrey Landis have looked at that possibility too (see the section on terraforming and paraterraforming) in the book.

I think the Moon would be a more interesting landscape to human eyes. It's much brighter - which tends to make us feel cheerful. By contrast, the sunlight on Mars at its brightest is half the illumination of Earth, and it's a dull brown in colour with the Mars dust suspended in the air filtering out the blue. Mars never has blue skies except around the sun at sunrise and sunset. Also there is little variation in colour in the landscape to human eyes. It's mainly dull grayish browns, with no blue and none of the bright glints catching the sunlight we have on Earth. I think that any Mars colonists would have a tendency towards depression just because of the rather gloomy sky and dull coloured landscape.

Once we can go to Mars, then we should explore it from orbit. This has no planetary protection issues if done well, and is an exciting mission for the crew. Using telepresence, they can also experience the surface more clearly, with digitally enhanced vision, even blue skies as they explore if they wish.

NASA's planetary protection officer Cassie Conley has talked about the advantages of exploring Mars from orbit first for purposes of planetary protection (see her appearance on David Livingston's the SpaceShow), and she makes strong statements about Elon Musk's rapid colonization plans for Mars as well, in an interview just before his big announcement here: Cassie Conley. Going to Mars Could Mess Up the Hunt for Alien Life

I take this a bit further than this. I don't think we should just delay the landing with orbital missions first, and aim for as much scientific exploration as possible before Mars becomes irreversibly contaminated after a human landing. I think that we should hold off from sending humans to the surface at all, until we have done an adequate exploration first. Then we can make our future decisions based on knowledge rather than conjecture. Our decision can be based on whatever we discover as we explore rather than our present guesses about what we might discover in the future.

As both of them say, and others also, we can do safe exploration of Mars from Earth. We can also explore with humans in Mars orbit, as soon as we have sorted out the safety issues for interplanetary missions without lifeboats to return to Earth in days.

TELEROBOTICS AS A FAST WAY FOR HUMANS TO EXPLORE MARS FROM ORBIT

We can explore Mars with robots on the surface controlled from Earth, as we have done so far, and broadband communications would speed up the pace of exploration in this way.

However we can explore Mars much more quickly, with humans in the loop. And you'd use an exciting and spectacular orbit for early stages of telerobotic exploration of Mars, following the HERRO plans. It comes in close to the poles of Mars, swings around over the sunny side in the equatorial regions and then out again close to the other pole, until Mars dwindles into a small distant planet - and does this twice every day. (Technically, it's a sun synchronous Molniya orbit).

Imagine the view! From space Mars looks quite home-like with its icecaps, deserts, even the occasional misty cloud, and the telerobotics will let you experience the Martian surface more directly than you could with spacecraft. You will be able to actually touch and see things on the surface without the spacesuit in your way and with enhanced vision, with blue sky also if you like. It's like being in the ISS, but orbiting another planet.


12th April 2011: International Space Station astronaut Cady Coleman takes pictures of the Earth from inside the cupola viewing window.- I've "photoshopped" in Hubble's photograph of Mars from 2003 to give an impression of the view of an astronaut exploring Mars from orbit.

This is a video I did which simulates the orbit they would use - in orbiter. I use a futuristic spacecraft as that was the easiest way to do it. Apart from that, it is the same as the orbit suggested for HERRO.

It would be a spectacular orbit and a tremendously interesting and exciting mission to explore Mars this way. The study for HERRO found that a single mission to explore Mars by telepresence from orbit would achieve more science return than three missions by the same number of crew to the surface - which of course would cost vastly more. Here is a powerpoint presentation from the HERRO team, with details of the comparison.

Then, you'd also have broadband streaming from Mars, in wide-field 3D binocular vision. It's amazing what a difference this makes, as I found out when I recently tried out the HT Vive 3D recreation of Apollo 11. We'd have similar 3D virtual reality experience of the Mars surface.

Also, it would actually be a much clearer vision than you'd have from the surface in spacesuits, digitally enhanced to make it easier to distinguish colours (without white balancing the Mars surface is an almost uniform reddish grayish brown to human eyes)|.

Here is the hololens vision, which though it's not telepresence, I think gives a good idea of what it might be like for those operating rovers on Mars in real time from orbit, some time in the future with this vision.

See Scientists Can Virtually Wander Around Mars for Miles with HoloLens

It's safer too, and comfortable and easy on the crew. No need to suit up. No risk from solar storms - at worst you have to go to a storm shelter in your spaceship, not rush back to your habitat as fast as you can to get out of the storm in time. No risk of falling over and damaging your spacesuit. And when you need to take a break, have your lunch, or whatever, you can just doff the VR set, and then come back, don it again and take it up again where you left off. Indeed you can leave the robot doing some task while you have your lunch or sleep.

Or more likely, you'd control many robots, a bit like the game of civilization. Most of them would be traveling, drilling, conducting experiments etc autonomously, and controlled by teams of researchers back on Earth. The crew in orbit would then step in to take over for any experiments or explorations that can benefit from real time telepresence.

It would be far faster. Curiosity has traveled 15.639 km as of writing this, and traveled 168.45 meters on its drive number 239 which I think is the furthest it's traveled in a day, Lunakhod 2 traveled more than a kilometer a day during it's third lunar day. That's with 1970s technology. A modern rover with modern technology, autonomous collision avoidance etc, could travel many kilometers an hour controlled from orbit, and do thousands of kilometers a year if needed.

Astronauts in orbit could do delicate experiments too requiring fine control. Many modern surgical operations are done via telerobotics with the surgeon in the same room as the patient for safety reasons. However experimentally an operation, the Lindbergh operation, was done on a patient in France by a surgeon in the US with French doctors at hand in case of anything going wrong and it went just fine. There are many other examples of telerobotic surgery over distances of hundreds of kilometers or more since then. We can definitely do delicate experiments on Mars by telerobotics.

There are many other robots we can send to Mars also. They can fly, bounce, go into small caves, go into places we could never explore in person. Any of these could also be controlled via telerobotics from orbit. For more on this see my See my Soaring, Buzzing, Floating, Hopping, Crawling And Inflatable Mars Rovers - Suggestions For UAE Mars Lander.

LUNAR GARDENING

We don't have to halt or slow down on human exploration to keep Mars protected from Earth microbes. Far from it; we can go somewhere closer to home, and more practical in the near term, the Moon. It's an exciting place to explore, and within our abilities, yet risky. It will stretch our current space capabilities nearly to the limit. We've been to the Moon for short periods only so far, in the early morning of the lunar day. It's far more challenging to stay there for weeks and months on end, safely.

Growing crops in space is likely to be a key to dealing with the high cost of resupply to missions in space, as a way to provide both food, and oxygen for the crew. The Moon has many resources we can use in situ to stay there for longer periods of time, and it's actually quite good for lunar gardening, at least as off world places go. Some of the sites on the Moon may well be the easiest places of all to build a habitable base in the inner solar system.

The peaks of eternal light at the poles have sunlight 24/7 nearly all the year round. They are also only a short distance from what seem to be vast resources of volatiles like water, ammonia, and carbon dioxide.

Then at lower latitudes, the probably vast caves provide radiation protection, protection against micrometeorites, a constant thermal environment actually slightly warmer than the poles, and it turns out that the two weeks long lunar night is something you can work with as a gardener.  Many plants can withstand 14 days of darkness with less than 50% reduction in crops if you reduce the temperatures to 2.5 - 3 degrees centigrade. And for plants that do need illumination during the night, the amount of power per colonist is much less than you'd think/ With modern techniques and LED lights you only need around 500 kWh per colonist to illuminate all the crops for an entire lunar night. This is an amount well within capabilities of fuel cells, hydrogen storage and advanced forms of batteries etc.

We need to explore the Moon first, probably robotically, before setting up a human base there. Robots are the easiest way to find the best location, and to prepare the habitats for humans. That will also give us practical experience in operating remote robots from Earth much closer and easier to control than the ones on Mars. That may help with Mars exploration too, once we have humans in orbit there, or broadband communications from Earth.

For details, see my An Astronaut Gardener On The Moon - Summits Of Sunlight And Vast Lunar Caves In Low Gravity which some sites have linked to as "The Complete Guide to Lunar Gardening"

For the resource comparison with Mars, see  See The Moon is resource rich and to find out about the science interest of the Moon, see  Moon science surprises, all in my Case for Moon First, also available  on kindle.

And longer term, let's try not to pin all our hopes for human exploration and perhaps colonization on Mars. The solar system is vast with many other places that may turn out to be far better for us, once we understand it better. These include the resources in the near Earth asteroids and the asteroid belt, see my Asteroid Resources Could Create Space Habs For Trillions; Land Area Of A Thousand Earths.

Indeed, if we could use the low impact, closed system, and efficient conveyer based agriculture suggested for space habitats, much of Earth itself is ripe for colonization, including its deserts and the oceans. With that technology, we could feed the entire world from only 2.5% of the Sahara desert. Also our oceans are four times the surface area of the land, in effect giving us four new "ocean world" planets. If we use space habitat technology for the seas as well, we could feed the population of those four extra "ocean world" planets, with four times the population of Earth, from only 0.5% of the Pacific ocean. We are talking here about minimal impact sea steading, in tethered floating sea cities.

These would be floating habitats that rely on just sea water, the air, and minimal imports from the rest of Earth, with no impact on sea life as they wouldn't need to fish and the land area is too small to shade out significant amounts of light if carefully situated. They would be constructed for far less cost than their equivalent in the vacuum of space, and would be far easier to maintain. There's no need to launch everything into orbit to set it up, no need for radiation shielding, and no need to purge the air of the noxious gases that build up inside any human occupied habitat (just open windows). Also there is no need to hold in the air against tons per square meter of outwards pressure, or to wear a spacesuit whenever you go outside. It's far easier to do seasteading than any form of space colonization. For more details, and the calculations, see my An astronaut gardener on the Moon - summits of sunlight and vast lunar caves in low gravity again.

In space, we can set up bases and supply stations in places like the moons of Mars or in orbit around Mars, in the Venus clouds, on Jupiter's moon Callisto, on Mercury, which has ice at its poles, and even further afield in the Saturn system or beyond. 

All that is possible with no planetary protection issues for most of the places. Venus clouds and Callisto would need preliminary assessment to make sure there are no issues, but are likely to be okay based on the knowledge so far. There are many places in the solar system that we can visit in person, as explorers who love science and see the scientific value of space exploration as paramount. The places we can't explore in person directly in this way can be explored from orbit by telepresence until we have a better idea of what we are dealing with. There will be no shortage of adventures and new horizons in this future.

ADDENDUM - PRESENT DAY HABITABILITY OF MARS AND WAYS TO DETECT PRESENT DAY LIFE THERE

Some of you may wonder what the fuss is about as you may have heard that the chance of life on or near the Mars surface is remote. After all, that was what most experts thought until the Phoenix lander in 2008. They thought that life on Mars was possible, but only deep down, for instance in geothermal hot spots isolated from the surface, or in a very deep liquid water layer (the hydrosphere) kilometers down below the frozen surface (the cryosphere).

But the situation has changed a lot since then. So here is an update on what has changed in the last eight years.

DIVERSITY OF POSSIBLE HABITATS FOR LIFE ON MARS

Experts still agree that the surface is a near vacuum and that fresh water exposed to the surface will evaporate rapidly and can't persist in present Mars conditions. But they have found many ways that various forms of salty and trapped water can survive on or near the surface, starting with the observation of what may be salty droplets forming on the legs of the Phoenix lander in 2008, and they also have found microbes and lichens that can make use of the 100% humidity of the thin Mars atmosphere at night, with no access to liquid water in any form.

The warm seasonal flows, or "recurrent slope lineae" are just one of many proposed types of habitat for life on the Mars surface. I surveyed the literature for Are There Habitats For Life On Mars? - Salty Seeps, Clear Ice Greenhouses, Ice Fumaroles, Dune Bioreactors,... (long detailed survey article with many cites)

There's an almost bewildering variety of suggestions for habitats on Mars for life. The main surface or near surface ones are (these links take you to the online booklet)

Most of those habitats are either above the permafrost layer or at most a few centimeters below it (the permafrost layer is typically 2 cms below the surface of the Mars regolith or less).

They are all almost impossible to detect from orbit, as they are covered by a few mms of the regolith, or lie beneath layers of ice, and most are also very small in physical extent. The only way we know to explore most of them and in many cases the only way to know for sure even if they exist, is with surface exploration missions, with landers or rovers.

That should be no surprise, because Mars is so cold and dry. It was probably as habitable as Earth originally, but after it lost most of its water, ice and atmosphere, the most habitable places now are like the Atacama desert and the dry valleys in Antarctica. They are cold, and dry, and any life is likely to be so slow growing and sparse that it has no noticeable effect on the atmosphere. Yet, if life did once get established on Mars, it may still be there.

It's rather like the future for Earth itself, which may became as uninhabitable as Mars, hundreds of millions of years in the future (unless some civilization either moves the Earth or shades it from the sun with vast thin film shades). It's likely to get too hot rather than too cold in our case. If so, the chances are that some small remnants of the formerly abundant life would survive long after most other species have gone extinct.

As Nilton Renno said, about his discovery of the possibility of droplets of water on salt ice interfaces on Mars,a droplet of water is like a swimming pool for a bacteria. Relicts of formerly abundant life would be no less interesting for being sparse and hard to detect. For more about this, see my article Why Mars Surface Life May Leave No Traces In Its Atmosphere: Our Rovers May Need To Go Up Close To See It

I think one of the most striking of these suggested habitats for planetary protection, though less well known, are the "flow like features" in Richardson crater near the south pole, as these suggest the possibility of fresh liquid water on Mars trapped below ice. The conclusions of Möhlmann's model are clear - if Mars does have clear blue ice as in Antarctica, then it should also have layers of pure fresh water trapped 10 - 20 cms below the surface, in conditions with surface temperatures as low as -56 C.

If so this may explain seasonal features found in Richardson crater. See my Does Ice Act As Greenhouse On Mars - Fresh Liquid Water Habitats In Spring 10-20 Cms Below Polar Ice?

Then, the methane plumes, if they are signs of life, surely must indicate abundant life in more habitable conditions, deep down, with some communication with the surface to let the gas escape. That would suggest of course that they could potentially be vulnerable to contamination by Earth microbes from the surface in the opposite direction. The plumes could also be caused by the inorganic process of serpentization. They may also be due the release of methane clathrates formed on early Mars by either organic or inorganic processes.

There's a wide variety of views on the topic of whether any of these potential habitats are in fact habitable by Earth life. If they exist, they may also be either too salty or too cold for life. Also some of the habitats that work in Mars simulation chambers and theoretical models of the surface may just not exist on Mars, as they depend on conditions we can't know about.

As an example, the fresh water model for the flow like features in Richardson crater depends on clear ice like the blue ice of Antarctica to act as a greenhouse to warm the ice to melting point half a meter below the surface. If similar semitransparent ice exists on Mars, the models show that there will be trapped layers of liquid water in the ice at certain times of the year, but we just don't know if Mars ice forms in transparent layers like that or not.

If these habitats do exist, again we have no idea whether they are inhabited by any form of indigenous life.

Views on this range from almost impossible to very likely, see Views on the possibility of present day life on or near the surface, and for the idea that some of these may be inhabitable but uninhabited, see Uninhabited habitats.

If these habitats do exist and are habitable, there are many Earth microbes which have been shown to be able to survive in Mars simulation conditions, and so could potentially survive there, contaminate them and make it difficult or impossible to study them to find out what was there originally.


Researchers at DLR (German equivalent of NASA) testing lichens in Mars simulation experiments. They showed that some Earth life (Lichens and strains of chrooccocidiopsis, a green algae) can survive Mars surface conditions and photosynthesize and metabolize, slowly, in absence of any water at all. They could make use of the humidity of the Mars atmosphere.

Though the absolute humidity is low, the relative humidity at night reaches 100% because of the large day / night swings in atmospheric pressure and temperature.

Here is a list of some of them, for the cites see my Candidate lifeforms for Mars in my Places on Mars to Look for Microbes, Lichens, ...:

  • Chroococcidiopsis - UV and radioresistant, and can form a single species ecosystem. It needs no other forms of life, and only requires CO2, sunlight and trace elements to survive.
  • Halobacteria - UV and radioresistant, photosynthetic (using hydrogen directly - proton pumps, doesn't generate oxygen or sulfur), can form single species ecosystems, and highly salt tolerant. Some are tolerant of perchlorates and even use them as an energy source, examples include Haloferax mediterranei, Haloferax denitrificans, Haloferax gibbonsii, Haloarcula marismortui, and Haloarcula vallismortis
  • Some species of Carnobacterium extracted from permafrost layers on Earth which are able to grow in Mars simulation chambers in conditions of low atmospheric pressure, low temperature and CO2 dominated atmosphere as for Mars.
  • Geobacter metallireducens - it uses Fe(III) as the sole electron acceptor, and can use organic compounds, molecular hydrogen, or elemental sulfur as the electron donor.
  • Alkalilimnicola ehrlichii MLHE-1 (Euryarchaeota) - able to use CO in Mars simulation conditions, in salty brine with low water potentials (−19 MPa), in temperature within range for the RSL, oxygen free with nitrate, and unaffected by magnesium perchlorate and low atmospheric pressure (10 mbar). Another candidate, Halorubrum str. BV (Proteobacteria) could use the CO with a water potential of −39.6 MPa
  • black molds The microcolonial fungi, Cryomyces antarcticus (an extremophile fungi, one of several from Antarctic dry deserts) and Knufia perforans, adapted and recovered metabolic activity during exposure to a simulated Mars environment for 7 days using only night time humidity of the air; no chemical signs of stress.
  • black yeast Exophiala jeanselmei, also adapted and recovered metabolic activity during exposure to a simulated Mars environment for 7 days using only night time humidity of the air; no chemical signs of stress.
  • Methanogens such as Methanosarcina barkeri[200] - only require CO2, hydrogen and trace elements. The hydrogen could come from geothermal sources, volcanic action or action of water on basalt.
  • Lichens such as Xanthoria elegans, Pleopsidium chlorophanum, and Circinaria gyrosa - some of these are able to metabolize and photosynthesize slowly in Mars simulation chambers using just the night time humidity, and have been shown to be able to survive Mars surface conditions such as the UV in Mars simulation experiments.

Most of these candidates, apart from the lichens, are single cell microbes (or microbial films). The closest Mars analogue habitats on Earth such as the hyper arid core of the Atacama desert are inhabited by microbes, with no multicellular life. So even if multicellular life evolved on Mars, it seems that most life on Mars is likely to be microbial.

SEARCHING FOR LIFE IN SITU WITH ROBOTS INSTEAD OF HUMANS

The astrobiologists have invented many ingenious instruments we can use to search for life on Mars. We don't need to send humans there. We haven't sent a single life detection instrument to Mars since the Viking landers in the 1970s. Many of these tests are exquisitely sensitive, some can detect a single molecule in a sample, or just a few cells.

The main approaches are

  • Test for metabolic activity (Microbial fuel cells)
  • Check distribution of organic molecules for lego principle that biological processes don't use all the organic molecules that can form in the conditions in which they live, but rather a selected set, for instance the 20 main amino acids used in terrestrial life. This would show up as spikes in the distribution of molecules in a sample, while abiotic processes would produce a much smoother distribution. Chris McKay calls this the "lego principle" See his What Is Life—and How Do We Search for It in Other Worlds?
  • Test for chiral molecules directly. Just as we standardize bolts and nuts have to have the same thread, as you can put a left hand threaded nut on a right hand threaded bolt, so also life tends to use the same handedness throughout. E.g. nearly all DNA spirals the same way (with some very unusual exceptions) and DNA spiraling in the opposite direction would confuse cell processes. Non life processes generally produce equal amounts of both types of molecule.

    Life uses almost exclusively right handed DNA like this


    Extra terrestrial life might use opposite handed spiral, as in the logo of the Astrobiology Society of Britain

    Logo of the Astrobiology society of Great Britain which shows a left handed double spiral, the opposite sense to Earth DNA. See also DNA's twist to the right is not to be meddled with, so let's lose the lefties

    Or it might be a single spiral, or some other shape altogether. But, as for Earth life, astrobiologists expect that nearly all the molecules would be of the same handedness. This makes it possible to design experiments to distinguish it from non life processes which produce both types of molecule, usually in equal numbers.

    Curiosity actually has one experiment on SAM, that could do this in principle, as one of the six gas chromatograph columns detects chirality Sample Analysis at Mars (SAM)It uses GC4 chirasilDex (Chiral compound separation) And apparently in the mass range to detect amino acids. The Mars Curiosity Rover Can Detect Chiral Compounds. Whether or not Curiosity uses this capability, detecting chirality is well within the range of possibility for future missions to Mars. The MOMA Gas Chromatograph for ExoMars will have one chiral column of its four, coupled to its mass spectrometer and it will be able to detect a wide range of organic molecules.
  • Feed it organics, e.g. amino acids and see if it takes it up and releases gases. This is the Viking labeled release experiment which lead to ambiguous results - but the updated version uses chiral food so you can tell if it preferentially incorporates a particular chirality which would be a clear sign of life.
  • Analyse the organics and see what there is there

    Examples:

    Raman spectrometry analyses scattered light emitted by a laser on the sample. It's sensitive, can measure the distribution of the organics and other compounds by pointing the laser at different points on the surface - and is non destructive so it can be applied first before any of the other tests.

    Urey, originally for ExoMars, with liquid extraction using high temperature, high pressure, sub critical water as a solvent is able to study the organics relatively unmodified. Also Astrobionibbler - similar idea to UREY, smaller, later development. Able to detect a single amino acid in a gram of soil.

    Planetary In-situ Capillary Electrophoresis System     “lab on a chip” – separate the organics by ionic mobility, by electrokinetic methods in sub millimeter capillaries with the fluid manipulations done within the chip itself.

    LDChip and Solid3, also the Life Marker Chip developed for ExoMars but descoped, using polyclonal antibodies to detect organics. These detect a wide range of organics not specific to DNA based life and are very sensitive. Solid3 was tested in the Atacama desert and was able to detect a layer of previously undiscovered life at a depth of 2 meters below the surface in the hyper-arid core of the desert
  • Scan with an electron microscope - high resolution electron microscopes are now small enough to send on a spaceship to Mars. They can also do chemical mapping for biosignatures. Non destructive so the samples can then be analysed later with other instruments
  • Just look with an optical microscope and see if you see something "wiggling" - send an optical microscope to Mars. If we saw something moving purposefully and engulfing food, it would be a reasonable guess that it is life of some sort.
  • DNA sequencing. Miniaturized DNA sequencer could work if we had a common ancestor right back to the very early solar system whenever DNA first evolved. This is in a reasonably advanced state. They say it could be ready to fly by 2018. Even if not based on DNA, you can still sequence it if it is similar in structure, but with a few extra bases and you guess what those are or find out through analysing it.

Many of these instruments are small, just a few cms in size, and requiring less than a watt of power, "labs on a chip" some of them already tested and space hardened. Yet none have flown yet. One of them, the Life Marker Chip, polyclonal antibodies experiment was originally included in the payload for ExoMars (more about it here) but was descoped. Before that, Urey was going to fly on ExoMars until NASA pulled out of the partnership.

MOMA will fly on ExoMars, with its ability to detect chiral compounds. Both ExoMars and Curiosity will be capable of Raman spectroscopy. But most of these instruments are not yet included in any mission payloads so we will need to wait a while before we get any results from them.

And, no, we don't need humans to drill. Indeed humans in spacesuits are clumsy at that as we found out with Apollo, and they can't use water as a lubricant. ExoMars will be able to drill down two meters, and the Insight lander was going to drill three to five meters.

The main technology used, the robotic self hammering mole, has potential to drill much deeper than either of those, and certainly to the ten meters depth needed to find organics not degraded by cosmic radiation and solar storms. These moles may eventually drill for tens and hundreds of meters, even for kilometers in Mars conditions at ten to twenty meters a day. Honeybee robotics say that a related technology, their inchworm mole will be capable of drilling up to tens of kilometers through soil, ice and rock without need for a tether and then return to the surface.

For more on this: Will NASA's Sample Return Answer Mars Life Questions? Need For Comparison With In Situ Search

FIND OUT MORE

I go into this in a lot more detail in my: 

  • Wait, Let's Not Rush To Be Multiplanetary Or Interstellar - A Comment On Elon Musk's Vision,
  • Does Elon Musk's Plan Violate The Outer Space Treaty - Planetary Protection For Mars After Human Crashes
  • An Astronaut Gardener On The Moon - Summits Of Sunlight And Vast Lunar Caves In Low Gravity

    • This article is part of "MOON FIRST Why Humans on Mars Right Now Are Bad for Science", available on kindle, and also to read for free online.


    I'm also the author of Case For Moon First, available online and on kindle, which expands on this theme of the Moon as the gateway to our solar system and the place to go first, to explore for its own sake, and leading to expanding exploration of the solar system all the way from Mercury through to Jupiter and beyond. 

    WHERE TO FIND "CASE FOR MOON FIRST"

    The kindle book may be useful if you want it formatted as a book, which you can read on your kindle, and also on most major smartphones, tablets and computers, using the free kindle reading app.

    FACEBOOK GROUP

    I've made a new facebook group which you can join to discuss this and other visions for human exploration with planetary protection and biological reversibility as core principles. Case for Moon for Humans - Open Ended with Planetary Protection at its Core

    SEE ALSO


    Robert Walker's posts - on Quora

    And on Science20


    Robert Walker's posts on Science20

    KINDLE BOOKSHELF ON MY AUTHOR'S PAGE

    And I have many other booklets on my kindle bookshelf

    My kindle books author's page on amazon