In the end, Levin’s colleagues, including Carl Sagan, decided it was a fluke — but Levin himself still insists it wasn’t, and Kaufman is inclined to give him the benefit of the doubt. Kaufman also bends over backward for the folks who say that bacterial remains can be found in meteorites. “Research in the past decade into the worlds of extremophiles, microbes and fossils,” he writes, “has proven that what’s true today often is overturned tomorrow, and what’s rejected today may be accepted tomorrow.”
Jeff Foust in the Space Review (April 4)
There are now astrobiology conferences, astrobiology journals, and even a NASA Astrobiology Institute. It’s in that environment of increased acceptance that Marc Kaufman surveys the state of astrobiology’s quest to discover life elsewhere in the universe in First Contact.
One interesting portion of the book looks at those people who still work in—or have been exiled to—the fringes of astrobiology even as the field gains wider acceptance. “[P]erhaps because of its urge for legitimacy, or because the discipline itself so often enters terra incognita, astrobiology has shown a consistent need to enforce a consensus,” casting aside those who differ, Kaufman writes. These people include Gil Levin, who argues the Labeled Release experiment on the Viking landers did, in fact, detect life on Mars; David McKay, who led the team that discovered what they still believe is evidence of life in Martian meteorite ALH 84001; and Richard Hoover**, who claims to see similar evidence for life in other meteorites. All three get fair, if somewhat sympathetic, profiles in one chapter of the book; Kaufman goes so far to lament that the three, presenting in the same session of a conference, draw only a handful of people—never mind that they’re speaking at a conference run by SPIE, an organization better known for optics and related technologies.
** Foust shows he doesn't follow Kaufman's openness on astrobiology, with the disparaging comment that “Hoover has gained notoriety for publishing a paper in the quixotic, controversial Journal of Cosmology about his asteroid life claims, an event that generated some media attention but was widely rebuffed as containing nothing new to support his claims.” No willingness there to assess the evidence carefully assembled by Hoover, just a desire to associate with some disgraceful attacks on him and the Journal which has given space to a score of commentaries on the study (Ed.)
Joel to Marc: How’d you get hooked on this topic of extraterrestrial life (which I know from experience can be quite absorbing)?
Marc to Joel: several years ago at MIT; I was a relatively new science writer ..three-day course was on “The Universe” .. Sara Seager, one of the top people in the field of exoplanets and their atmospheres, told us unequivocally that life (or signs of life) would be detected in the next generation or so.... my reaction was: My God, what a story! And it took off from there.
What I found, as I quite literally circled the globe to meet with scientists doing related work, was that most of them share Seager’s conclusion. And they didn’t agree based on a wish or hope, but based on the science that was coming out of the field of astrobiology.
...what I learned is that the scientific logic that leads to the existence of ET life is strong and getting stronger... now science has many of the tools and much more of the needed knowledge to find what might really be out there. It won’t be easy, it won’t be quick, and it’s sure to be controversial -- most everything involving astrobiology sparks some controversy. But that’s the very exciting direction where things are headed.
Joel to Marc: .. the Sagan standard (“extraordinary claims require extraordinary evidence”) is a little too strict and impractical, that it makes it impossible to reach any conclusion; is that a fair interpretation of your point? Your book gives us the latest on the ongoing ALH84001 (Mars rock) controversy, and you seem to be generally sympathetic to McKay and Gibson without going quite so far as to say you think they’re right. ...I read Bob Hazen’s book “Genesis,” and he really lays out the backroom brawling and gives us a glimpse of the egos involved. But what’s your hunch?
Marc to Joel: First on McKay: His team really went out on a limb when they published. A key part of their discovery involved magnetites -- microbes that use and leave traces of planetary magnetism. At the time, there had been no finding of any magnetic field remnant on Mars. That came 6 or 7 years later. Their research also required the presence of water to form certain minerals. While the water on Mars discussion was already underway in 1995, it has picked up enormous strength since and now the idea that Mars had an early “wet and warm” phase is nearing consensus.
As for the mini microfossil, McKay pretty much told me he wished he hadn’t gone with that one. Subsequent research by others has found that mini microfossils can and do exists on Earth, but McKay says to forget them because he’s finding those bigger microfossils in clearly Martian meteorites. That research has not been sufficiently developed to pass the “is it terrestrial contamination?” test and has not appeared in mainstream science journals. McKay is convinced they were once alive and that they are not earthly contamination, but I’m agnostic on that one. Richard Hoover of NASA/Marshall famously believes he is finding similar microfossils in non-Martian meteorites, but his recent paper on that in the new journal Cosmology got trashed, and properly so.
Putting it all together, the case for life in ALH84001 is stronger now than it was in 1995. Nonetheless, the consensus view remains that McKay et al did not find life in the rock. I personally think the jury is still out, but the evidence is looking stronger for McKay. (The guy who reviewed my book, Mike Brown from Caltech) makes an aside that he is leaning more towards accepting McKay’s position.)
On “extraordinary claims requiring extraordinary evidence,” ...what’s so fascinating about astrobiology now is that much of the really important work is being done outside that realm of extraordinary claims.
Exoplanets -- and those in habitable zones -- presence throughout the cosmos of the elements and compounds we assume are needed for life - complex carbons are found in nebulae, amino acids come flying in on meteorites, CO2 and methane are in atmospheres of distant planets, as well as Mars. No real “extraordinary claims” here; just the building of a strong scientific logic in favor of ET life. The very much new and improved research on extremophiles strengthens the case, I believe, because it shows life to be phenomenally tenacious and able to survive in myriad environments we long assumed were uninhabitable.
As for the endless controversies... as you know well, scientific “discoveries” very seldom give final answers and are always being challenged... one of the great strengths of science, it seems to me.
And very final thought ...Carl Sagan was one of the reviewers of the McKay paper for Science. He clearly thought it either cleared the bar or that the bar was set higher than it should be. And despite all the scientific conflict that followed ALH84001, do remember that the finding was a (the?) catalyst for setting up the NASA astrobiology program.
Joel to Marc: How the heck did non-living stuff become alive? Are you a panspermia guy (I hope that’s not probing into too personal of a realm)?
Marc to Joel: Finding (a) second genesis would be revolutionary, but we can be almost 100 pc certain that any other life in our solar system would not have evolved beyond a microbial state. So we’d be left with this conundrum: We would know that life is most likely common beyond our solar system, but the vast distances would make it impossible to come into contact with that potential life (except through measurements of exoplanet atmospheres, etc.)
And regarding panspermia, we do know that Mars was far more hospitable to life than Earth back in the period of 3.8-4.5 billion years ago, and that Earth was definitely inhospitable for a good chunk of that time. Yet some scientists are convinced they have found evidence of microbial life on Earth from about 3.8 billion years ago, though others remain skeptical. But if that 3.8 billion year evidence becomes more solid and even confirmed, then life was present here not too long (in cosmic term) from the time when it was seemingly impossible. Did it come from Mars? We truly will never know**, because the evidence is long gone. But I probably would put my money on the theory that we are, in the final analysis, all Martians.
** uncharacteristic blinkered assertion (Ed.)