I’ve dabbled in astrobiology now and again — wrote some stuff — but haven’t paid really close attention for a few years, and due to this intellectual sloth I fear I got fuzzy on many of the key details of the quest for extraterrestrial life, like whether they’d actually found it yet, and, if so, how many tentacles did it have, and whether the creatures were friendly. But now I’m completely up to date, and clear on all this, because I’ve read a new book by a colleague here, indeed a fellow member of the acclaimed science pod at The Post: Marc Kaufman, author of “First Contact: Scientific Breakthroughs in the Hunt for Life Beyond Earth.

Herewith, a Q&A, by email:

Joel to Marc: Wow! You went everywhere, saw everyone, chewed on the biggest questions in astrobiology. Your brain must be halfway toward exploding with all the cosmic questions of life, the universe and everything. Right off the bat: How’d you get hooked on this topic of extraterrestrial life (which I know from experience can be quite absorbing)?

Tell me a little bit about your plan of attack, as far as trying to nail down an intrinsically squishy topic that has the unfortunate quality of being about something of which there are currently no known examples. I remember years ago, in a brief phone interview, I tried to get Stephen Jay Gould to weigh in on ET, and he said simply, “No data.”

Your book makes clear that we’re in a different place than we were a decade or two ago – most notably with all these exoplanets, and the very strong implication that small, rocky planets in the habitable zone of a star are commonplace (billions and billions out there, surely). And life is so adaptable here on earth, one wouldn’t want to bet against its chances of surviving and thriving and evolving and mutating and maybe even getting all technological and whatnot on other worlds.

Still: Isn’t this an iffy business, innately? Until we have Example Two of life?

Marc to Joel:

I got into extraterrestrial studies the old-fashioned way. I was at a Knight journalism “boot camp” several years ago at MIT; I was a relatively new science writer and was eager to soak up whatever I could. The three-day course was on “The Universe,” and included talks by MIT and Harvard profs on topics from supermassive black holes to galaxy formation to the multiverse. It was all very interesting, but it REALLY spoke to me when 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. This is a woman who was given a tenured chair at MIT at the tender age of 34, so is clearly very highly regarded.

Ever the journalist, 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.

No life has been found, or conclusively found, beyond Earth, but what I learned is that the scientific logic that leads to the existence of ET life is strong and getting stronger. Humans have imagined forever that living or life-like forces or beings are up in space -- filling the skies with gods, angels, heavens, djinns and more recently UFOs and ET -- but 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:

Are all fields this controversial, or is this one particularly so because of the stakes involved? Any claim is an extraordinary claim when it comes to ET; you suggest that perhaps 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 remember the day they announced the discovery at NASA headquarters: It was huge news, except Bill Schopf rejoiced in being the skunk at the party. Later I read Bob Hazen’s book “Genesis,” and he really lays out the backroom brawling and gives us a glimpse of the egos involved. Bottom line, what’s your take: Do you think the stuff in the rock is Martian? You don’t have to answer that! Doubt is fine around here; uncertainty is welcome. 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 the bigger question of “extraordinary claims requiring extraordinary evidence,” that seems like a good rule of thumb to me. But 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 -- are a key aspect of the whole life-beyond-Earth story, and there is no dispute that they exist. Some may disagree with a particular finding -- like the recent Paul Butler/Steven Vogt paper on allegedly finding the first habitable zone planet -- but a few weeks later Bulter’s former partner and now rival, Geoffrey Marcy, published a paper that estimated a billion or more habitable zone planets in the Milky Way alone. Same dynamic with the growing understanding of the presence throughout the cosmos of the elements and compounds we assume are needed for life. We now know that complex carbons are found in nebulae, we know that amino acids come flying in on meteorites, we know that 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. If the material is out there and the planets are out there, then why wouldn’t life begin on one of the zillion of possible sites? 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.

The “extraordinary claims” debate seems best fitted for issues like whether Viking found signs of life or, with the MSL set to start sending back info in August 2012, whether it finds organics that could form (or have formed) the basis of life.

As for the endless controversies, seems to me several factors are at work. First is that these are scientists often working at the edge of what we know, so what they come up with tends to be new. New means not yet confirmed, and other scientists reasonably want to see confirmation, which is sometimes hard (and expensive) to get. So some big findings tend to be left untested. Second is that being involved with the experiment or finding that “proves” extraterrestrial life is a ticket of eternal scientific fame. So the competition is fierce and a lot of brilliant and type A individuals are in the field. Sparks will inevitably fly. (Witness the fact that Bill Schopf came under the same kind of harsh criticism he dished out to McKay in the years after ALH84001. Different work, but same high stakes.) And finally, as you know well, scientific “discoveries” very seldom give final answers and are always being challenged. It’s no doubt aggravating for all involved, but is one of the great strengths of science, it seems to me.

And very final thought regarding “extraordinary claims and evidence.” As I believe I wrote in the book, none other than 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. So you never exactly know what a scientific finding -- be it embraced or rejected -- will ultimately produce.

Whew -- I know this is more than you need/want, but once I get going I find it hard to stop...

Joel to Marc:

I agree with your premise that, with all that material out there, and all the chances for life to appear and evolve, it’s hard to imagine that we’re alone in the universe. But most of the Drake Equation is still unknown, correct? Marcy and Butler et al have done amazing work on the number of planets, and we’re getting a better sense, slowly, of how many might be in the habitable zone, but aren’t we still pretty much nowhere on the origin of life? 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)? It seems to me that even if you posit lots of habitable worlds, a fairly small fraction might be in the same kind of stable position as the Earth, which has had 4 billion amazingly serene years to play around with life forms and ultimately produce one that memorize the infield fly rule. My hunch is that intelligent life is highly dispersed, as in, nothing like that anywhere near us and probably so far away in time and space that we’re not going to be conversing with ET until we invent wormholes or whatever. Is that too pessimistic? And do we really want to meet intelligent aliens? You quote Hawking saying it’s not a good idea. They’ll show up with a “How To Serve Humans” book, right?

Marc to Joel:

Again, Joel, wonderful questions.

A little background first on me and SETI. I’ve never been a fan or even particularly knowledgeable person about SETI, and I started my book reporting with a very high degree of skepticism about the idea. I still don’t think the chances of SETI finding distant life are particularly good, but here’s the realization I came to while walking one morning thru their radio telescope array up in Hat Creek (in a beautiful valley below Mt. Shasta and Mt. Lassen): What else do we have?

With the closest star system something like 4.20 lightyears away at Alpha Centauri, and with human travel anywhere near the speed of light total science fiction, we don’t have many alternatives if we’re in fact interested in trying to learn whether technologically evolved life exists out there. So SETI began to have a different feel for me. Yes, it’s still mostly a crapshoot. And yes, the Drake Equation has so many wide variables that it’s unclear to me that it really tells us anything particularly useful. But the whole SETI enterprise has been substantially upgraded in recent years -- largely because of a $30 million donation by Paul Allen, co-founder of Microsoft -- and that allows their listening to be far more systematic. They still monitor only tiny bits of the sky, but they’re much better at doing it. And with the advent of optical SETI (where astronomers set up scopes to monitor unusual, laser-like flashes of light,) the process is evolving. The main OSETI operation is associated with Harvard and Princeton, so it’s clearly science-based, though still a long shot.

SETI wouldn’t matter so much were it not for this scenario: Let’s say in the years ahead that scientists conclude there is, or was, life on Mars or Titan or Europa or somewhere in our solar system. And let’s say the life there is/was of a different sort than what we have here -- where all DNA is made up of particular molecules and only those molecules, and with but one replication process for everything. If life somehow began both on Earth and somewhere else in our quite insignificant solar system, then the probability of life being a cosmic commonplace suddenly goes up dramatically. Finding that 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 wold make it impossible to come into contact with that potential life (except through measurements of exoplanet atmospheres, etc.) Given these constraints, it seems that a program like SETI (longshot though it is) makes sense.

And then there’s METI -- messaging extraterrestrial intelligence. Even those familiar with SETI often don’t realize that all it does is listen, and that OSETI only observes. They could send out messages, but except for a handful of formal or informal efforts, that messaging has never taken place -- unless, of course, you consider the massive radio chatter put out by the people of Earth over the past century and a half to be a messaging of a sort. But some people in the field think it’s time to change all that, to begin sending out radio and laser signals to star systems where we know exoplanets are present. I tend to think it’s a good idea, but many others are concerned that it would, in effect, tell the bad guys we’re here. Stephen Hawking famously said in recent years that METI is a bad idea because the history of technologically sophisticated civilizations interacting with less sophisticated civilizations has almost always been bad for the less advanced. And the assumption here is that we would be in that technologically inferior position. This doesn’t seem like a scientific question to me but rather one about a person’s (or a society’s) optimism or pessimism.

And finally, on the equally longshot chances of a primordial soup coming up with life. I don’t see how there can be other than two choices here: Either life was formed through the combination of non-living molecules over time and in particular places, or it was created. Not sure there’s another alternative. Since I don’t believe the latter, I’m most interested in learning how the former might have occurred. The charter of astrobiology, if you will, states that it’s mission is both to find life beyond Earth and to learn how life started here. I think it’s quite likely that the building blocks for Earthly life came from afar, in the form of meteorites with amino acids and nucleobases and, who knows, maybe Martian meteorites with hibernating microbes. Synethetic biologist here are pushing the envelope in terms of cobbling together strands of supply-house DNA, and making something that can self replicate on its own. This process remains in its relative infancy, but it may well produce a proof of concept (that a self-sustaining replicator can come together from non-living parts) in the years ahed.

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.

MK

[Marc will be signing books at the Smithsonian National Air & Space Museum on Sunday, May 1, from 1 to 3 p.m., and will be at Politics & Prose on May 15 at 5 p.m. His website is www.habitablezones.com.]