This might seem like a reason for going there. But is actually a reason for not going - at least not to the surface, so a bit of a paradox here :).
Because it's the most interesting place to look for life in our solar system - so - also that makes it one of the most vulnerable places in the solar system - to Earth life.
It's been long recognized, since the 1970s, that Mars is one of the places most in need of protection from Earth life, with many precautions taken to sterilize our rovers sent to Mars. And new research suggests it is probably more vulnerable than we realised, as recently as six years ago.
Carl Sagan once calculated that a single microbe, if it reproduced as slowly as once a month - and if nothing else limited it - it could reach a population enough for all the soil on the Earth in a decade.
Of course Mars soil is not going to be able to support a population like that. But it suggests that if there are habitats on Mars reasonably widespread and easy to get to (e.g. in the dust storms) - then might not take long at all in years for them all to be colonized.
If Earth microbes start to reproduce on Mars, there will be no way we can reverse that. With hardy dormant microbes spread widely in the dust storms - how could you ever find them all and remove them from Mars?
And any human has a trillion microbes in a thousand species just on your skin - and many more in your food, atmosphere, clothes etc. Only a tiny percent of those are known species - most are completely unknown, never been studied. And - as microbes retain their capabilities for extreme environments when they are living in more hospitable environments - then some may be able to survive on Mars.
And - a crash of a human occupied vehicle on Mars counts as an immediate fail of planetary protection - at least by the guidelines used so far for sterilizing robotic vehicles to Mars.
So - we risk contaminating the very place that is most interesting for the search for life. It's got an atmosphere - almost a vacuum - but still enough to raise dust storms that can help to scatter dormant life anywhere on Mars from a crash site - and the dust also protects from UV - and as for cosmic radiation - it is only sterilizing over time periods of thousands of years.
And are several possible candidates now for present day habitats for life on Mars under serious consideration.
So when you realize also that the experiments they want to send to the surface of Mars can detect even a single amino acid in a sample - is pretty clear you want to keep it clear of humans and all the microbes that come with us - at least until you have time to find out if there is life there - i.e. probably for some decades.
Anywhere else in the solar system is much less of an issue except
There are other places that need study first include Ceres, Encladus - even the poles of the Moon would need some scientific study first I think before sending humans there - just because the layers of ice would be of such scientific interest for the early solar system - need to know what the effect would be of humans landing there on the information we can find about the early solar system first.
Venus atmosphere also possibly, and Phobos - just a bit of care in case there is viable present day Mars life there. And a few other places.
Apart from possibly the ice at the poles though, the Moon is an ideal place actually to study the effects of humans landing on a place outside of Earth.
We have a lot of suggestions about ways that humans just possibly might be able to explore somewhere without contaminating it - but it's never been studied in reality.
The Moon is easy to get to, close to hand - and planetary protection regulations currently just say you have to document what you do on the Moon.
So - we can legitimately send humans to the lunar surface - and then - study to see how much they contaminate the surrounding soil around their base. That could inform us about decisions about whether to use humans to explore other solar system bodies.
The Apollo landings certainly did - the Apollo Astronauts left their bodily wastes in bags on the Moon, so that at least is still up there.
E.g. would you send humans to a comet to study its organics, like Rosetta? Or would they contaminate it with Earth based microbes so much that their measurements would be meaningless? Can we do anything to prevent that happening, or is it inevitable?
We don't really have much data to decide questions like that at present.
But for Mars - I think surely we do have enough data to know that a human landing on Mars is - if not a certain contamination - a greatly increased risk of contaminating it over an unmanned rover or use of telerobotics.
For unmanned rovers to Mars the target originally (though no longer required to calculate it for each mission) was that the risk of contamination should be less than 1 in 10,000 per mission (and is even that probability too high given what you risk losing by way of understanding of life if the planetary protection fails?).
Doesn't seem too likely that a human mission to Mars could have such a low risk of a crash landing - never mind the issue of keeping it free of contamination after the landing if they managed to survive. And - in the original calculations by Carl Sagan and others - a hard landing of an unsterilized spacecraft on Mars was automatically counted as 100% probability of contamination.
But what humans can surely do, if not land on sensitive objects, is to explore them via telepresence. Which may well be the way ahead anyway.
Telepresence has the great benefit that you don't need to expose humans to cosmic radiation or the dangers of a one person spacesuit (basically a tiny and fragile spaceship) surrounded by vacuum. And spacesuits are clumsy anyway - though spacesuit technology is improving - I think telepresence and telerobotics is as well - rapidly - some people have suggested that because of the danger of spacesuits - and the improving telerobotics - space walks may soon become something of a thing of the past.
So - I don't see humans on the surface of Mars n the near future. But do see humans quite possibly in orbit around Mars - if a way can be found to do that without a risk of a crash landing on Mars - and without of course contaminating Mars with wastes from the human orbiting spaceship - all wastes need to be disposed of in a way that makes sure they can never impact on Mars.
If you could do that - then humans in orbit around Mars could drive robots on the surface by telepresence - and pick things up using robot hands and haptic feedback - and run scientific experiments in real time - and control numerous small flying drones and insect like rovers and such like exploring the surface of Mars - and explore as much in a few days as our robots controlled from Earth can explore in many years.
So - I see - prime reason not to go to the Mars surface is because Mars is likely to have life. But that's also a prime reason to go to Mars orbit and explore it via telepresence. If we do find life on Mars there might well be quite a lot of public interest in that - especially if it turns out to be different from Earth life in some way, and money made available - to visit it and study it from orbit.
I think that depends on whether we can develop the capability to keep astronauts healthy in space for years on end, with no resupply from the Earth. If we could do that - then we could hugely reduce the cost of the ISS (only need to send astronauts and supplies there every year or two rather than many times a year) and for the same budget have human outposts e.g. at L2 position and L1 positions close to the Moon - and - once those are shown to be safe, with crews staying there for multi year missions with no problems turning up - also have humans go to Mars as well. All for the same cost as our current missions to LEO and the amount we are spending every year to maintain a continuous human presence in LEO.
However - as our robots get more autonomous - there are ideas for rovers for follow up to ExoMars that can drive distances on Mars with no direct control from Earth - if that becomes possible - then robots might be all we need all the way through.
Hard to say - they would also have to do decision making for the experiments etc. But might happen.
If that happens - well -that means - we have real time streaming HD video probably by then from all those rovers on Mars - and them learning interesting things about it all the time. After all if we sent humans to Mars - how many would get to actually experience it?
But this way the entire population of the Earth will get to experience these on going explorations of Mars - probably as life streaming 3D HD video of the surface. We are all then like the Mars explorers exploring new frontiers :).
Both ways - either if we explore just as robots, or - as humans in orbit controlling robots on the surface - an exciting and fascinating future.
REASON FOR HUMANS NOT TO GO - BECAUSE IT IS SO INTERESTING FOR LIFE - SO MUST BE PROTECTED - AS IT IS ALSO VULNERABLE
Because it's the most interesting place to look for life in our solar system - so - also that makes it one of the most vulnerable places in the solar system - to Earth life.
It's been long recognized, since the 1970s, that Mars is one of the places most in need of protection from Earth life, with many precautions taken to sterilize our rovers sent to Mars. And new research suggests it is probably more vulnerable than we realised, as recently as six years ago.
Carl Sagan once calculated that a single microbe, if it reproduced as slowly as once a month - and if nothing else limited it - it could reach a population enough for all the soil on the Earth in a decade.
Of course Mars soil is not going to be able to support a population like that. But it suggests that if there are habitats on Mars reasonably widespread and easy to get to (e.g. in the dust storms) - then might not take long at all in years for them all to be colonized.
If Earth microbes start to reproduce on Mars, there will be no way we can reverse that. With hardy dormant microbes spread widely in the dust storms - how could you ever find them all and remove them from Mars?
And any human has a trillion microbes in a thousand species just on your skin - and many more in your food, atmosphere, clothes etc. Only a tiny percent of those are known species - most are completely unknown, never been studied. And - as microbes retain their capabilities for extreme environments when they are living in more hospitable environments - then some may be able to survive on Mars.
And - a crash of a human occupied vehicle on Mars counts as an immediate fail of planetary protection - at least by the guidelines used so far for sterilizing robotic vehicles to Mars.
So - we risk contaminating the very place that is most interesting for the search for life. It's got an atmosphere - almost a vacuum - but still enough to raise dust storms that can help to scatter dormant life anywhere on Mars from a crash site - and the dust also protects from UV - and as for cosmic radiation - it is only sterilizing over time periods of thousands of years.
PLACES THAT COULD BE CONTAMINATED ON MARS
And are several possible candidates now for present day habitats for life on Mars under serious consideration.
- The warm seasonal flows - these come first as there is currently no other explanation for them - they happen at temperatures above 0C so can't be dry ice phenomenon - and are seasonal - get longer as the year progresses and dry out in autumn - and no connection with the wind. No other ideas suggested for them so far except some form of liquid - probably salty water. (These are rare features - not to be confused with the dry gullies, or the bright streaks or various other phenomena which are more common, and most are due to dry ice or wind effects).
- Phoenix discovery of salts - and the drops on the Phoenix legs which are probably deliquescing salts - giving a way that microbes can get water from the 100% very cold night time humidity on Mars - same trick is used by microbes in the Atacama desert
- Solid state greenhouse effect that is thought to cause the Martian dry ice geysers may also melt ice enough for life in liquid layers trapped below translucent ice
- DLR experiments that show that some microbes and lichens can actually take up water directly from simulated Mars night time atmosphere - and metabolize - and photosynthesize in simulated Mars sunlight (UV and all) - so may be able to survive on the surface of Mars even without water at all (some Earth microbes can do this also, even at far below 100% humidity, again in the Atacama desert)
So when you realize also that the experiments they want to send to the surface of Mars can detect even a single amino acid in a sample - is pretty clear you want to keep it clear of humans and all the microbes that come with us - at least until you have time to find out if there is life there - i.e. probably for some decades.
WHERE CAN WE GO?
Anywhere else in the solar system is much less of an issue except
- Mars
- Europa
- Encladus
There are other places that need study first include Ceres, Encladus - even the poles of the Moon would need some scientific study first I think before sending humans there - just because the layers of ice would be of such scientific interest for the early solar system - need to know what the effect would be of humans landing there on the information we can find about the early solar system first.
Venus atmosphere also possibly, and Phobos - just a bit of care in case there is viable present day Mars life there. And a few other places.
MOON AS IDEAL PLACE TO STUDY WHAT HAPPENS AFTER A HUMAN LANDING - BY WAY OF BIOLOGICAL CONTAMINATION
Apart from possibly the ice at the poles though, the Moon is an ideal place actually to study the effects of humans landing on a place outside of Earth.
We have a lot of suggestions about ways that humans just possibly might be able to explore somewhere without contaminating it - but it's never been studied in reality.
The Moon is easy to get to, close to hand - and planetary protection regulations currently just say you have to document what you do on the Moon.
So - we can legitimately send humans to the lunar surface - and then - study to see how much they contaminate the surrounding soil around their base. That could inform us about decisions about whether to use humans to explore other solar system bodies.
The Apollo landings certainly did - the Apollo Astronauts left their bodily wastes in bags on the Moon, so that at least is still up there.
E.g. would you send humans to a comet to study its organics, like Rosetta? Or would they contaminate it with Earth based microbes so much that their measurements would be meaningless? Can we do anything to prevent that happening, or is it inevitable?
We don't really have much data to decide questions like that at present.
MARS RISK SHOULD BE LESS THAN 1 IN 10000 PER MISSION
But for Mars - I think surely we do have enough data to know that a human landing on Mars is - if not a certain contamination - a greatly increased risk of contaminating it over an unmanned rover or use of telerobotics.
For unmanned rovers to Mars the target originally (though no longer required to calculate it for each mission) was that the risk of contamination should be less than 1 in 10,000 per mission (and is even that probability too high given what you risk losing by way of understanding of life if the planetary protection fails?).
Doesn't seem too likely that a human mission to Mars could have such a low risk of a crash landing - never mind the issue of keeping it free of contamination after the landing if they managed to survive. And - in the original calculations by Carl Sagan and others - a hard landing of an unsterilized spacecraft on Mars was automatically counted as 100% probability of contamination.
TELEPRESENCE
But what humans can surely do, if not land on sensitive objects, is to explore them via telepresence. Which may well be the way ahead anyway.
Telepresence has the great benefit that you don't need to expose humans to cosmic radiation or the dangers of a one person spacesuit (basically a tiny and fragile spaceship) surrounded by vacuum. And spacesuits are clumsy anyway - though spacesuit technology is improving - I think telepresence and telerobotics is as well - rapidly - some people have suggested that because of the danger of spacesuits - and the improving telerobotics - space walks may soon become something of a thing of the past.
So - I don't see humans on the surface of Mars n the near future. But do see humans quite possibly in orbit around Mars - if a way can be found to do that without a risk of a crash landing on Mars - and without of course contaminating Mars with wastes from the human orbiting spaceship - all wastes need to be disposed of in a way that makes sure they can never impact on Mars.
If you could do that - then humans in orbit around Mars could drive robots on the surface by telepresence - and pick things up using robot hands and haptic feedback - and run scientific experiments in real time - and control numerous small flying drones and insect like rovers and such like exploring the surface of Mars - and explore as much in a few days as our robots controlled from Earth can explore in many years.
SO BOTH REASON NOT TO GO TO SURFACE - BUT REASON TO GO TO ORBIT - POSSIBLY...
So - I see - prime reason not to go to the Mars surface is because Mars is likely to have life. But that's also a prime reason to go to Mars orbit and explore it via telepresence. If we do find life on Mars there might well be quite a lot of public interest in that - especially if it turns out to be different from Earth life in some way, and money made available - to visit it and study it from orbit.
I think that depends on whether we can develop the capability to keep astronauts healthy in space for years on end, with no resupply from the Earth. If we could do that - then we could hugely reduce the cost of the ISS (only need to send astronauts and supplies there every year or two rather than many times a year) and for the same budget have human outposts e.g. at L2 position and L1 positions close to the Moon - and - once those are shown to be safe, with crews staying there for multi year missions with no problems turning up - also have humans go to Mars as well. All for the same cost as our current missions to LEO and the amount we are spending every year to maintain a continuous human presence in LEO.
However - as our robots get more autonomous - there are ideas for rovers for follow up to ExoMars that can drive distances on Mars with no direct control from Earth - if that becomes possible - then robots might be all we need all the way through.
Hard to say - they would also have to do decision making for the experiments etc. But might happen.
If that happens - well -that means - we have real time streaming HD video probably by then from all those rovers on Mars - and them learning interesting things about it all the time. After all if we sent humans to Mars - how many would get to actually experience it?
But this way the entire population of the Earth will get to experience these on going explorations of Mars - probably as life streaming 3D HD video of the surface. We are all then like the Mars explorers exploring new frontiers :).
Both ways - either if we explore just as robots, or - as humans in orbit controlling robots on the surface - an exciting and fascinating future.
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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