The headline and the statement are both bunk. NASA is not closing in on finding extraterrestrial life, and it is not getting “closer and closer” to finding a world with extraterrestrial life.
A fundamental truth about extraterrestrial life (one that NASA never tells us) is that the natural origin of life on another planet would require fantastically improbable arrangements of matter. You can get a rough analogy of the unlikelihood of this by imagining how improbable it would be if someone were to throw a large box of 1000 scrabble blocks on the ground, and the blocks were to accidentally spell out a very complex computer program.
In fact, such an analogy greatly underestimates the improbability of life accidentally appearing from mere chemicals. By all accounts the most primitive cell requires at least 100 functional proteins, most of which require more than a hundred amino acids arranged in just the right way. So a better analogy would be a dumpster of scrabble blocks dumped on the ground, with the totality of 10,000 tossed scrabble blocks forming into a single coherent computer program accomplishing some fantastically complex task. It is not at all true that if a single protein of the 100 or more required were to form by chance, that such a protein would stick around for a long time until the other required proteins originated. Protein molecules don't self-reproduce unless they are part of a living cell requiring 100 or more proteins. So you would need to have a fantastically improbable stroke of luck in which all or almost all of the minimum required proteins by chance originated at about the same time.
This is merely one mountainous difficulty for the origin of life. A separate but equally great mountainous difficulty is the need for a genetic code (a complex system of symbolic representations), the need for self-reproducing nucleic acids, and the need for homochirality, something with apparently less than one chance in a quintillion of occurring accidentally.
Using only chemical considerations, we can therefore compare the search for extraterrestrial life on any planet to buying a lottery ticket. But we would have to imagine a lottery with insanely bad odds, in which the chance of winning is much smaller than the chance of you winning a billion dollars in the Powerball lottery.
Given such a reality, is it correct for NASA to suggest that the more planets are searched for signs of extraterrestrial life, the “closer and closer” we get to finding it? No, it is not correct. You don't get “closer and closer” to getting a billion-dollar jackpot in the lottery by buying more tickets. If one is trying to design some new type of machine, and your designs get better and better, beginning to more closely resemble your desired design, then you could honesty say that you are getting “closer and closer” to your target. But you do not get “closer and closer” to reaching some incredibly improbable result by making additional searches that are each very unlikely to succeed. You don't get “closer and closer” to finding Bigfoot with each additional search of a forest patch, and you don't get “closer and closer” to finding extraterrestrial life with each new planet searched.
The latest baloney on this topic from NASA is only the latest of quite a few overconfident statements NASA experts have made on this topic. In 2015 Ellen Stofan (a chief scientist at NASA) predicted, “I think we are going to have strong indications of life beyond Earth within a decade, and I think we're going to have definitive evidence within 20 to 30 years.” There is no scientific basis for such optimism, and based on purely natural considerations it would be reasonable to predict no success will occur in the next 100 years.
Stofan tried to support her prediction by stating “we know where to look.” No, we absolutely do not know where to look. We would know where to look if we had some reason to believe that a particular extraterrestrial planet had a high chance of having life. We have no reason to believe that about any planet. A NASA scientist predicting that extraterrestrial life will soon be found on the basis of “we know where to look” (habitable planets) is about as convincing as a Loch Ness monster specialist claiming that the Loch Ness monster will soon be found because we know where to look (in the Loch Ness lake in Scotland).
The people who make such statements seem to be believers in a kind of Easy Abiogenesis tenet, which maintains (contrary to the relevant scientific facts) that life will naturally appear from non-life on any planet with suitable conditions. Such a belief is contradicted by the following:
- The abundant biological
reasons (previously discussed) for thinking that abiogenesis (a
natural origin of life from non-life) would require a state of
organization fantastically unlikely to naturally occur by chance on
even 1 in a million planets.
- The complete failure of
scientists to reproduce abiogenesis in a lab, or even produce a
single functional protein in a lab simulating early Earth conditions
(a single one of the building blocks of life).
- The complete failure of
all attempts to search for extraterrestrial radio signals, which
presumably would be abundant if it were true that abiogenesis was
- The existence of only
one genetic code in all of Earth's life, something we would not
expect if abiogenesis was relatively easy, in which case life would
have arisen multiple times on Earth, with each separate origin
having a different genetic code.
NASA has a plan to look for signs that life once existed on Mars. It is a plan that is rather stupid. They plan to send in 2020 a new Mars rover that will dig into the Martian soil and retrieve samples. Will the samples then be analyzed in a way sufficient to prove living things or traces of life that once existed? Not really (see the postscript at the end of this post for a technical note on this). Will the samples be sent back to Earth for analysis by human scientists? No, the 2020 mission will have no such capability.
Instead, the not-very-brilliant plan is to simply gather soil and rock samples and just leave them on the ground as “caches” that might be retrieved by some future “Mars cache retrieval” mission, which might then return them to Earth for analysis by human scientists. There are no firm plans for such a retrieval mission, and no one knows how it might work.
Giving us an example of why you can't trust the journal Nature as a very reliable source of information, a Nature article has the title “The $2.4-billion plan to steal a rock from Mars,” and the headline “NASA is now building the rover that it hopes will bring back signs of life on the red planet.” But the article then states something very different:
Once it arrives, the rover will drive across the Martian surface and fill each tube with dirt, rock or air. Then it will seal the tubes, place them on the ground, and wait — for years, or possibly decades — for another spacecraft to retrieve them and fly them back to Earth.
This is how a NASA page describes this bizarre plan:
The mission takes the next step by not only seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life itself. The Mars 2020 rover introduces a drill that can collect core samples of the most promising rocks and soils and set them aside in a "cache" on the surface of Mars. A future mission could potentially return these samples to Earth. That would help scientists study the samples in laboratories with special room-sized equipment that would be too large to take to Mars.
This seems like a rather absurd way to spend money looking for extraterrestrial life. The Mars 2020 mission will cost billions, and some future mission that might retrieve these surface “caches” would cost billions more. The chance of actually finding evidence that life once existed on Mars would be very, very small, because of the reasons previously discussed. There would also be a high risk that the samples would never be returned, because no one has ever done anything like retrieving samples from another planet and returning them to Earth.
A manned mission to Mars could retrieve these “sample caches,” but why would the astronauts even go to the trouble of searching for them, when it would be much easier for them to just drill themselves to get a soil sample wherever they were?
The NASA Mars 2020 mission sounds poorly conceived compared to a European 2020 Mars rover mission that will drill for soil samples and actually analyze them for life. The European Space Agency site says, “The rover will collect samples and analyse them with next-generation instruments – a fully fledged automated laboratory on Mars.” (I discuss in the technical postscript of this post the key thing the ESA rover will have that the NASA rover won't.)
One of the astrobiology scientists has the same unfounded optimism as the previously quoted NASA scientist, and stated that there's a “50-50” chance of finding life on Mars. Based on the actual difficulty of life appearing from chemicals under the best of conditions, we should instead assume the actual chance of success as very much less than 1 in a thousand.
Spending billions to search for life on Mars makes little sense as a way to spend astrobiology dollars. If you want to search for extraterrestrial life in a way that gives you “bang for the buck,” the most sensible strategy is to search for radio signals from other solar systems. For one tenth of the cost of an unmanned Mars mission, you can check not just one planet but 1000 planets, looking for radio signals.
In the very unlikely event that it succeeds, the best we would ever get from a Mars soil retrieval mission is evidence of microbes on Mars. That would be a relatively boring find that might hold the public's interest for no more than two weeks. A search for extraterrestrial radio signals, on the other hand, might actually produce photos of extraterrestrials and photos of extraterrestrial cities (visual data can be transmitted over radio using the right coding system). That would hold the public's interest permanently.
A scientist named Golombek claims that the NASA Mars 2020 rover is “our best chance of finding out if life evolved independently on another world and that life here is not just a lucky accident.” It is not any such thing. The best chance of finding out if life evolved independently on another world is to have a much less expensive mission that checks many planets looking for radio signals from civilizations.
A statement such as Golombek's reveals the ideological motivation of looking for life on Mars. It's all about scientists hoping to prove (against all indications) that Earth getting life was not a very lucky event. Our scientists are troubled by the idea that when life originated here, Earth seemingly got some specially lucky blessing, some miracle that seems providential; and they want to spend billions as a kind of analgesic to remove this discomfort (finding life on a planet like Mars with bad conditions might prove that the origin of life is rather automatic). The scientist who asks for billions to search for underground traces of Mars life to try to prove a far-fetched belief (the Easy Abiogenesis tenet that the origin of life on Earth wasn't very lucky or providential) is rather like some fundamentalist who asks for millions so he can search for underground wooden traces of Noah's Ark.
Contrary to the overblown hype you may have read last summer (debunked here), scientists have not at all found the building blocks of life on Mars. The building blocks of life are proteins and nucleic acids, and no such things have been found on Mars. And since no one has even found a single amino acid on Mars, it is not even true that the building blocks of the building blocks of life have been found there. For this reason, a mission to look for life on Mars is rather like calling in a structural engineer to determine whether a habitable apartment building exists at some site when no one has even reported seeing bricks at that site.
Postscript: Referring to the 2020 NASA Mars mission, the National Geographic has a story calling a scientist someone who designed "a device to look for signs of past life on Mars." The device in question is called PIXL, short for planetary instrument for X-ray lithography. But it is mainly an instrument for detecting elemental compositions, and does not seem capable of actually verifying that microbes once existed in the soil. You can't distinguish between non-biological organic compounds and traces of life merely by looking at elemental compositions. The instrument's optical resolution of .1 millimeter (100 microns) isn't powerful enough to see something bacteria-sized, which would only be about .5 micron to 5 microns. What we would like to see in the technical documents related to this PIXL instrument is mention of some test in which the device was able to distinguish between sterile soil and soil that contained (or once contained) bacteria. I don't see that in the technical documents, although one of them refers to a too-easy test involving blueberries.
But apparently the ESA rover scheduled for 2020 will have the ability to find a unique signature of life, for according to this page, their rover will be able to detect homochirality. Homochirality is one of the little-discussed marvels of life -- the fact that virtually all amino acids in living things are left-handed, and virtually all sugars are right-handed (which is not at all what we see when such things are synthesized in labs). Checking for homochirality is a great way to search for life, but the very requirement of homochirality (an incredibly improbable thing for you to get by chance) is an additional reason for thinking Mars won't have accidentally spawned life. Why isn't the NASA 2020 Mars rover also looking for homochirality?