The scientific process is rarely about "proof". If scientists start bandying around words like proof in front of you, be skeptical. What these scientists should have been doing is "testing the hypothesis" that these crystals are life. We really can't expect too much from the scientific process at this stage with so little data, and any scientists (or science media people) that claim that this sort of evidence is "proof" is really being quite irresponsible.
Agreed Mars does not have a significant magnetic field. However, there is some evidence that it has had a magnetic field in the past (remnant magnetism). Mars has also been extremely volcanically active throughout most of it's history (until at least 1 billion years ago, possibly even in the last few tens of millions of years), which implies that there was at least a partially molten core for much of this time. In addition, mantle convection models predict that each major volcanic centre on Mars would only be active for about 1 million years out of 100, and seeing as there are somewhat less than 100 volcanic centres, it seems unlikely that, even if Mars was active, it would be active at any one time (i.e. present). A molten core is not essential for volcanism, even when the heat source is nuclear decay (as we suspect for Mars). It seems unlikely that a planet could remain active for long (over billions of years timescale) without a magnetic field, but the possibility that Mars could be active at some time over the next few million years has not been ruled out by planetary scientists.
Whether Mars remains volcanically active or not, it certainly was 3.9 billion years ago, and the concensus seems to be that Mars did have a strong magnetic field then. Given the evidence of water-carved channels on the surface and volcanism dating from this time, it is likely that the atmosphere was thicker, and that water was stable on the surface for long periods of time. As such, this would have been a very suitable environment for the evolution of life, as we understand the process.
Yes, they are discovering bacterial and other forms of life (extremophiles) in weird places on the Earth. For example, algae living within rocks in sub-zero temperatures in the Antarctic, that can reside in a frozen state for years, even centuries, until freak warm/wet spells allow it to breed. There are even microorganisms that flourish within nuclear reactors. So yes, I (and most scientists I know) see no reason not to think that life couldn't have survived on Mars. In fact, most of the biologists that I know think that if life ever did exist on Mars, then it would have undoubtedly adapted to survive almost anything that nature could throw at it, and therefore that if there was life, there still is.
However, nearly everyone I know working in this field seems to think that some sort of fluid, preferably water, would be necessary.
One thing that the new discoveries (suboceanics life, microorganisms in frozen climates, etc.) have demonstrated, however, is that sunlight is less directly important than previously though, which is good news for those hoping to find life on Mars.
Of course, this doesn't eliminate the possibility that life might evolve completely unlike that on Earth. However, the only tested models for life are those on Earth, and I'm not a biochemist (just a physicist who studies volcanoes and water on Mars) so I can't really say much about alternative models without being extremely speculative. Just from a structural point of view however, I expect that some sort of fluid is necessary, just so a lifeform can have moving parts (and movement is involved in cell splitting), and I don't think there is any evidence for materials in a fluid state on asteroids (unlike Mars - loads of ice and loads of fluvial features). They may be able to transport life in cryostasis, but I doubt that life could flourish or even be sustained for long in an active state without fluids.
Then there is also the possibility of different DNA handedness, although there is some debate as to whether or not this is plausible. The truth is that it's difficult to prove anything. We don't fully understand how life on Earth arose. However, if we can find life that started on other planets it should help answer some of the unknowns - one good reason to look for it. -k
We can hope. It seems to be working in the UK. Funding for "astrobiology" has increased incredibly. I admit to using the bandwagon ("... and implications for the evolution of life on Mars") myself. We also have the ESA Mars Express mission and the UK Beagle 2 lander (the only robotic mission with a chance, however small, of detecting life on Mars).;) -k
Not necessarily true. What if the life form was based upon DNA that had clearly not evolved on Earth. Okay, proof is a strong word in science - you could argue that nothing is proven. However, it would be quite convincing.
Also, Earth has a much larger gravitational pull (and hence escape velocity) than Mars, and is closer to the sun. Therefore transport from Mars to Earth is much more likely than Earth to Mars. It is far from satisfactorily demonstrated that meteorites could be transported from Earth to Mars, though I have to say that it seems probably, in small numbers. It has also not been demonstrated that life could withstand the energy of impact and re-entry.
-Karl
Dr Karl Mitchell Planetary Science Research Group Environmental Science Dept Lancaster University UK
Not true: very little (if any) of the life on Mars findings have been proven or disproven. All that is happening is that some scientists are presenting their evidence that supports the hypothesis that life has existed or even does exist on Mars. Other scientists are scrutinising this evidence and poking holes in their analyses. This is part of the scientific process and only to be expected. What is needed is a new form of data. We can argue about magnetite in Mars meteorites for years but it probably won't solve anything. What we need is a fresh sample, that hasn't been superheated on impact and re-entry.
How all this is portrayed in the media is often misleading and, yes, that is sometimes the fault of the scientists as much as the science journalists. The truth is that the media tends to dumb down science for the general public in the belief that real science is too boring for them. Whether this is justified or not is a matter of opinion.
Scientific press releases can be a good way to get research funding. It is also a very dangerous game to play, as scientists are often misquoted to their expense.
-Karl
Dr Karl Mitchell Planetary Science Research Group Environmental Science Dept. Lancaster University UK
The rock is from Mars. Atmosphere isotope ratios are unambiguous in such cases. Every planet has it's own "signature" that, with the right equipment, is possible to detect. This was demonstrated ages ago by Monica Grady and others in the UK.
You're correct that it's easier to get a meteorite from a smaller body, and we do get loads of them (positively identified Martian meteorites number in the dozens rather than the thousans). However, Mars is massive and has had many massive impacts. The amount of material ejected from it's surface means that it would be amazing if none had reached the Earth.
Also, regarding life, it's unlikely that life would have evolved on any body that did not have liquid water. Liquid water has always been unstable on asteroids, whereas there have significant periods of Martian history (likely when the impact occurred) where liquid water was thought to be stable, possibly over hundreds of millions of years. In fact, there are even points on present day Mars where, for a limited period during the year, water can be stable on the surface. Of course, if you believe Fred Hoyle, life could be everywhere, but, based on an Earth model, life seems far more likely to have evolved on Earth and/or Mars.
The evidence for this being a result of biological activity is still highly ambiguous however, which is why we need to get samples back from Mars.
-Karl
Dr Karl Mitchell Planetary Science Research Group Environmental Science Department Lancaster University UK
Of course. The ability to import windows between systems (setting the DISPLAY variable). This is invaluable... especially for a system as GUI orientated as a Mac. Besides that, it makes porting already existing X apps all that much easier.
Slashdot Mirror
The scientific process is rarely about "proof". If scientists start bandying around words like proof in front of you, be skeptical. What these scientists should have been doing is "testing the hypothesis" that these crystals are life. We really can't expect too much from the scientific process at this stage with so little data, and any scientists (or science media people) that claim that this sort of evidence is "proof" is really being quite irresponsible.
Sorry. I didn't see this e-mail first. Your reply was very clear.
Agreed Mars does not have a significant magnetic field. However, there is some evidence that it has had a magnetic field in the past (remnant magnetism). Mars has also been extremely volcanically active throughout most of it's history (until at least 1 billion years ago, possibly even in the last few tens of millions of years), which implies that there was at least a partially molten core for much of this time. In addition, mantle convection models predict that each major volcanic centre on Mars would only be active for about 1 million years out of 100, and seeing as there are somewhat less than 100 volcanic centres, it seems unlikely that, even if Mars was active, it would be active at any one time (i.e. present). A molten core is not essential for volcanism, even when the heat source is nuclear decay (as we suspect for Mars). It seems unlikely that a planet could remain active for long (over billions of years timescale) without a magnetic field, but the possibility that Mars could be active at some time over the next few million years has not been ruled out by planetary scientists.
Whether Mars remains volcanically active or not, it certainly was 3.9 billion years ago, and the concensus seems to be that Mars did have a strong magnetic field then. Given the evidence of water-carved channels on the surface and volcanism dating from this time, it is likely that the atmosphere was thicker, and that water was stable on the surface for long periods of time. As such, this would have been a very suitable environment for the evolution of life, as we understand the process.
-Karl
Yes, they are discovering bacterial and other forms of life (extremophiles) in weird places on the Earth. For example, algae living within rocks in sub-zero temperatures in the Antarctic, that can reside in a frozen state for years, even centuries, until freak warm/wet spells allow it to breed. There are even microorganisms that flourish within nuclear reactors. So yes, I (and most scientists I know) see no reason not to think that life couldn't have survived on Mars. In fact, most of the biologists that I know think that if life ever did exist on Mars, then it would have undoubtedly adapted to survive almost anything that nature could throw at it, and therefore that if there was life, there still is.
However, nearly everyone I know working in this field seems to think that some sort of fluid, preferably water, would be necessary.
One thing that the new discoveries (suboceanics life, microorganisms in frozen climates, etc.) have demonstrated, however, is that sunlight is less directly important than previously though, which is good news for those hoping to find life on Mars.
Of course, this doesn't eliminate the possibility that life might evolve completely unlike that on Earth. However, the only tested models for life are those on Earth, and I'm not a biochemist (just a physicist who studies volcanoes and water on Mars) so I can't really say much about alternative models without being extremely speculative. Just from a structural point of view however, I expect that some sort of fluid is necessary, just so a lifeform can have moving parts (and movement is involved in cell splitting), and I don't think there is any evidence for materials in a fluid state on asteroids (unlike Mars - loads of ice and loads of fluvial features). They may be able to transport life in cryostasis, but I doubt that life could flourish or even be sustained for long in an active state without fluids.
All the best,
-Karl
Then there is also the possibility of different DNA handedness, although there is some debate as to whether or not this is plausible. The truth is that it's difficult to prove anything. We don't fully understand how life on Earth arose. However, if we can find life that started on other planets it should help answer some of the unknowns - one good reason to look for it.
-k
We can hope. It seems to be working in the UK. Funding for "astrobiology" has increased incredibly. I admit to using the bandwagon ("... and implications for the evolution of life on Mars") myself. We also have the ESA Mars Express mission and the UK Beagle 2 lander (the only robotic mission with a chance, however small, of detecting life on Mars). ;)
-k
Not necessarily true. What if the life form was based upon DNA that had clearly not evolved on Earth. Okay, proof is a strong word in science - you could argue that nothing is proven. However, it would be quite convincing.
Also, Earth has a much larger gravitational pull (and hence escape velocity) than Mars, and is closer to the sun. Therefore transport from Mars to Earth is much more likely than Earth to Mars. It is far from satisfactorily demonstrated that meteorites could be transported from Earth to Mars, though I have to say that it seems probably, in small numbers. It has also not been demonstrated that life could withstand the energy of impact and re-entry.
-Karl
Dr Karl Mitchell
Planetary Science Research Group
Environmental Science Dept
Lancaster University
UK
Not true: very little (if any) of the life on Mars findings have been proven or disproven. All that is happening is that some scientists are presenting their evidence that supports the hypothesis that life has existed or even does exist on Mars. Other scientists are scrutinising this evidence and poking holes in their analyses. This is part of the scientific process and only to be expected. What is needed is a new form of data. We can argue about magnetite in Mars meteorites for years but it probably won't solve anything. What we need is a fresh sample, that hasn't been superheated on impact and re-entry.
How all this is portrayed in the media is often misleading and, yes, that is sometimes the fault of the scientists as much as the science journalists. The truth is that the media tends to dumb down science for the general public in the belief that real science is too boring for them. Whether this is justified or not is a matter of opinion.
Scientific press releases can be a good way to get research funding. It is also a very dangerous game to play, as scientists are often misquoted to their expense.
-Karl
Dr Karl Mitchell
Planetary Science Research Group
Environmental Science Dept.
Lancaster University
UK
The rock is from Mars. Atmosphere isotope ratios are unambiguous in such cases. Every planet has it's own "signature" that, with the right equipment, is possible to detect. This was demonstrated ages ago by Monica Grady and others in the UK.
You're correct that it's easier to get a meteorite from a smaller body, and we do get loads of them (positively identified Martian meteorites number in the dozens rather than the thousans). However, Mars is massive and has had many massive impacts. The amount of material ejected from it's surface means that it would be amazing if none had reached the Earth.
Also, regarding life, it's unlikely that life would have evolved on any body that did not have liquid water. Liquid water has always been unstable on asteroids, whereas there have significant periods of Martian history (likely when the impact occurred) where liquid water was thought to be stable, possibly over hundreds of millions of years. In fact, there are even points on present day Mars where, for a limited period during the year, water can be stable on the surface. Of course, if you believe Fred Hoyle, life could be everywhere, but, based on an Earth model, life seems far more likely to have evolved on Earth and/or Mars.
The evidence for this being a result of biological activity is still highly ambiguous however, which is why we need to get samples back from Mars.
-Karl
Dr Karl Mitchell
Planetary Science Research Group
Environmental Science Department
Lancaster University
UK
Of course. The ability to import windows between systems (setting the DISPLAY variable). This is invaluable ... especially for a system as GUI orientated as a Mac. Besides that, it makes porting already existing X apps all that much easier.