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Looking for Martian life that’s not like life on Earth October 18, 2010

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Another day, another correction to my presentation!

I concluded my talk in class last week by talking about the expert problem associated with ALH84001 – how can anyone really be an expert on signs of life on a Martian meteorite? I also added that the whole thing is riding on the assumption that Martian life is similar to life on Earth.

Now I’ve listened to talk by Chris McKay from NASA (an interesting speaker – I’ve seen him on some documentaries before). He was talking to the Astrobiology and Space Exploration class at Stanford. It doesn’t seem to be on YouTube, but you can find it on iTunes – search for Astrobiology in the iTunesU section, find the Astrobiology and Space Exploration (Winter 2008) course, and it’s talk 16 – “Exploration and Colonization of Mars – Why and How?”

McKay makes it very clear that his goal is to find life on Mars that isn’t similar to life on Earth. Some quotes:

What we’re looking for is the possibility of a second genesis of life. We’re looking for an alternate type of life.

We’re not asking the question “Is there life on Mars?” We’re asking the question “Is there alien life on Mars?” And that’s an important distinction and it will influence where we ought to go look for life.

Why do we want to find aliens? The main reason we want to find aliens, scientifically, is that it would allow us for the first time to do what I would call comparative biochemistry.

But there’s also the broader issue of life in the universe. If we were to find out that in our own little solar system life start twice, separately and independently, that would be convincing evidence that life is common in the universe.

We’re going (to Mars) to look for evidence of a second genesis. So what exactly does that mean? Well first it means that fossils are not what we’re looking for. Fossils are evidence of life, but we’re not satisfied with finding evidence of life on Mars. We want to know what that life’s relationship is to life on Earth. Or asked another way, we’re saying “Is there life on Mars, and is that Martian life on our tree of life?”

What we’d like is to find an organism that is not part of our family.

It’s not clear how widely this goal is shared within NASA.

He goes on to make an interesting argument about how one might go about looking for life that’s not related to life on Earth. The argument involves Lego and Lincoln Logs, and well worth a listen.

 

History repeating itself? October 18, 2010

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I mentioned briefly last week that back in 1961 there was a similar controversy about signs of life in a meteorite. It turns out to be a pretty interesting story, so here’s a bit more about it.

The Orgueil meteorite landed in France in 1864, and it was soon realised that it contained organic compounds, which raised questions about extraterrestrial life. The meteorite even got involved in the spontaneous regeneration debate – even if life doesn’t spontaneously regenerate on Earth, maybe it does in space? The meteorite was even studied by Louis Pasteur.

Fast forward to 1961, and a team led by Bart Nagy at Fordham University announced that the Orgueil meteorite did indeed contain biological material and something similar to fossilised algae (this sounds very similar to ALH84001…..)

By 1963, however, the claims (which received front-page coverage in newspapers around the world) had been discredited when it was shown that the signs of alien life were in fact Earth-based pollen or fungi. Later in 1965, someone tried to use glue a seed capsule onto the meteorite in order to claim that it showed signs of extraterrestrial life!

See here for more info from meteorites.org, a meteorite blog.

NASA’s goals for Mars exploration – a correction October 14, 2010

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Just a quick update to something I mentioned in my class presentation on Wednesday. I said that NASA’s aims for Mars exploration focused on finding water and environments that would be (or would have been) suitable for life, rather than finding evidence of life itself. I’m pleased to say that I wasn’t completely correct (!).

Here is the agenda and associated presentations for a recent workshop to discuss possible landing sites for the Mars Science Laboratory (MSL), a new Mars rover to be launched next year. There is more discussion about direct detection of life than I had thought. One of the sections of the workshop is “Habitability and Biosignatures”, and there are a number of talks that address the issue of how MSL could find evidence of biology on Mars. Talks such as “Optimizing exploration for organic biosignatures” and “Preservation of Evidence of Ancient Environments and Life on Mars” suggest that NASA isn’t as cautious about setting the goal of detecting life as I had suggested.

The embargo October 5, 2010

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I’ve touched on this briefly before, but now I’m going to look at the events surrounding the publication of the initial ALH84001 paper in more detail. It presents an interesting case study on the embargo of scientific papers. Once again, I’m drawing primarily on Vincent Kiernan’s incredibly well-researched paper from Public Understanding of Science.

David McKay and his team from NASA submitted their paper to Science in April 1996. The editors realised how significant it was, and restricted access to it by the journal’s staff in order to limit any leaks. After a few revisions, the paper was accepted in July, with publication planned for the 16 August issue.

NASA’s management pushed for an earlier publication date, in order to limit leaks and avoid a news clash with a big political convention scheduled for the week of 16 July, but the authors couldn’t make their final revisions in time to get it published earlier.

The normal Science embargo process provides journalists with copies of papers one week before they are published, but NASA was so worried about leaks that they convinced Science to only tell journalists three days prior to publication. A press conference was scheduled for 15 August, the day before publication.

In late July and early August, things started to ramp up. Debates raged about how to word press releases – was the ALH84001 evidence “circumstantial” or did it “strongly suggest” Martian life? There were several briefings at the White House, rumours began to circulate about the research, and eventually a small piece about ALH84001 appeared in the 5 August issue of the small publication Space News. A reporter from CBS News noticed it and contacted Science on 6 August.  They tried to convince the reporter to sit on the story, but other journalists were picking up the scent and it became clear that something had to give. By the end of day, Science issued a press release describing the research and lifted the embargo.

NASA had tried to convince Science to stop the journalists from publishing early – but only because they were planning an early press conference for the next day, and their research team was in transit to Washington and wouldn’t be available to the media. This led to some fairly inaccurate stories about the research being circulated – CNN reported that the fossilised bacteria looks like maggots, without mentioning that they were thousands of times smaller than maggots!

The story hit the prime time news on 6 August, the NASA press conference happened the next day, and President Clinton released statement. And then the fun began!

And now for the video! October 2, 2010

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Here’s an excellent 1996 documentary from the BBC Horizons program about ALH84001 and the controversy surrounding it. Part 1 kicks off with a great story about an episode from 1961 when another meteorite was thought to have evidence of life – only to have that evidence turn out to be pollen grains that blew in through the window.

The whole thing is about an hour long – if you’re only going to watch one of them, go for Part 1 – it’s a great introduction to the whole controversy, and also has video of Bill Clinton’s statement and the NASA press conference that I’ve been searching for.

Part 1

Part 2

Part 3

Part 4

Part 5

Considering that this was produced in 1996, just a few months after the story broke, I’d say this is a fantastic piece of reporting. Enjoy!

A picture is worth a hundred words September 28, 2010

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It’s time to make this blog a bit more than just words. I’ve gathered together some pictures relating to ALH84001, hoping this will provide a bit of context and make things easier to imagine.

It’s also relevant because so much of the scientific dispute seems to boil down to interpretations of what people see in the meteorite – a certain feature might look like it’s biological to one person, but appear geological to another.

Here’s the source of it all – ALH84001. Surprisingly small, considering all the fuss it’s generated:

Here are some detailed shots (done mostly with electron microscopes) of the interesting features inside ALH84001. Some of the debate has been about whether these features are actually due to the way the samples are prepared before being imaged by the electron microscope, or whether they are due to bacterial contamination during the thousands of years the meteorite sat in the ice in Antarctica.

And here’s evidence of how much this controversy caught the public’s imagination – it has its own stamp!

Alternate endings September 27, 2010

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A couple of weeks ago I said that the only way the ALH84001 controversy is going to be settled is by the discovery of more meteorites similar to ALH84001. I was looking at the issue pretty narrowly, thinking about ALH84001 itself as the controversy. If you widen out a bit and think about life on Mars as the controversy, there are plenty of ways that issue could be settled.

The first thing to note is that it’s far easier to prove that there was (or is) life on Mars than it is to prove that there wasn’t (or isn’t).

Here are some of the possible missions to Mars that could shed some light on the issue:

  • A manned mission to Mars – it seems obvious that having a human on the surface of the planet, analysing the rocks and soil, would get to the bottom of this mystery quicker than any other approach.  The question is who can afford to pay for it?
  • A sample return mission to Mars – having a robot return Martian samples to Earth would allow scientists to target specific areas of Mars for study, instead of the arbitrary samples they find in Martian meteorites, and would reduce (but not eliminate) the issues around contamination. There have been sample return missions to the Moon, a comet and an asteroid, but there’s nothing planned for Mars yet.
  • More advanced robotic missions to Mars – the next chance for this is the Mars Science Laboratory mission, launching in late 2011. It’s not really designed to look for life directly, but it will look at things like the chemistry and minerals on the surface to see if they could support life.

If any of these found evidence for life, it would immediately give strength to the ALH84001 claim for life (because the paradigm about Martian life would have changed), or perhaps make the whole dispute irrelevant.

Bill Clinton on ALH84001 September 21, 2010

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Here’s the text of the  statement from President Clinton in August 1996, at the time of the original ALH84001 research:

“Good afternoon. I’m glad to be joined by my science and technology adviser, Dr. Jack Gibbons, to make a few comments about today’s announcement by NASA.

This is the product of years of exploration and months of intensive study by some of the world’s most distinguished scientists. Like all discoveries, this one will and should continue to be reviewed, examined and scrutinized. It must be confirmed by other scientists. But clearly, the fact that something of this magnitude is being explored is another vindication of America’s space program and our continuing support for it, even in these tough financial times. I am determined that the American space program will put it’s full intellectual power and technological prowess behind the search for further evidence of life on Mars.

First, I have asked Administrator Goldin to ensure that this finding is subject to a methodical process of further peer review and validation. Second, I have asked the Vice President to convene at the White House before the end of the year a bipartisan space summit on the future of America’s space program. A significant purpose of this summit will be to discuss how America should pursue answers to the scientific questions raised by this finding. Third, we are committed to the aggressive plan we have put in place for robotic exploration of Mars. America’s next unmanned mission to Mars is scheduled to lift off from the Kennedy Space Center in November. It will be followed by a second mission in December. I should tell you that the first mission is scheduled to land on Mars on July the 4th, 1997 — Independence Day.

It is well worth contemplating how we reached this moment of discovery. More than 4 billion years ago this piece of rock was formed as a part of the original crust of Mars. After billions of years it broke from the surface and began a 16 million year journey through space that would end here on Earth. It arrived in a meteor shower 13,000 years ago. And in 1984 an American scientist on an annual U.S. government mission to search for meteors on Antarctica picked it up and took it to be studied. Appropriately, it was the first rock to be picked up that year — rock number 84001.

Today, rock 84001 speaks to us across all those billions of years and millions of miles. It speaks of the possibility of life. If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered. Its implications are as far-reaching and awe-inspiring as can be imagined. Even as it promises answers to some of our oldest questions, it poses still others even more fundamental.

We will continue to listen closely to what it has to say as we continue the search for answers and for knowledge that is as old as humanity itself but essential to our people’s future”.

A couple of things that really struck me about this:

Although there’s plenty of caution in the statement (“this one will and should continue to be reviewed, examined and scrutinized”, “it must be confirmed by other scientists”, and “ensure that this finding is subject to a methodical process of further peer review and validation”), the distinct impression from the end of the statement is that a *big* discovery with profound implications for humankind has just been made.

Secondly, there’s direct link that’s being made between ALH84001 and orders for NASA (and presumably funding) to explore Mars further.

It seems like both of these points served to inflate the controversy – having the president proclaim your research before the paper has been published rubs a lot of people the wrong way, and having a direct link between your research and funding for your organisation make it more difficult for that organisation to question or step back from the controversial findings.

It makes me wonder if things would have turned out differently if the story had been handled differently from Day 1.

Looking for the next ALH84001 September 19, 2010

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I’ve mentioned previously that the only way the ALH84001 controversy is going to be resolved is by finding more Martian meteorites from the same era, and that Antarctica is the most likely place where they might be found. Here are a couple of blogs from people who have been involved in NASA’s Antarctic meteorite search efforts:

http://dawn.jpl.nasa.gov/feature_stories/antarctica.asp

http://www.planetary.org/explore/topics/planetary_analogs/ansmet.html

It sounds like brutally hard work – a team of 6 people spend 6 weeks at a time out in remote areas of Antarctica, and they can find up to 1000 meteorites per season.

NASA is the main player in the search for meteorites in Antarctica, but the Japanese and the Europeans have programs there as well. It would be interesting to see what would happen if a meteorite similar to ALH84001 was found by one of these groups, instead of NASA.

The initial response to the ALH84001 claim September 16, 2010

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The response to the original ALH84001 paper was swift and cautious, at best.

In the same issue of Science as the original paper, there was a news article describing the initial reaction. Clearly the editors of the journal were already aware at this point of how controversial the issue would become. The headline was “Ancient Life on Mars? A meteorite has yielded evidence – but not proof – of ancient life on Mars. The claim has excited skeptical fascination among scientists but has made no converts so far”

In addition to quoting people on both sides of the debate:

“I think it’s very unlikely they have remnants of biological activity,” says William Schopf of the University of California, Los Angeles, who has spent his career separating microfossils of early life on Earth from imposters.

“I’m not convinced,” says interplanetary dust particle specialist Donald Brownlee of the University of Washington, “but I think they have made a credible case that these things could be microfossils. It’s unprecedented. It’s one of the most important things in science, it it’s true. [Exobiology] is intellectually interesting, but without any data, it’s just speculation; I think there’s some data now.”

The article concluded by warning that the issue would not be resolved for some time:

Don’t expect this drama to be wrapped up in the next TV season. The sort of supporting evidence that would convince Schopf and other critics could be slow in coming. As Schopf quoted Cornell exobiologist Carl Sagan: “Extraordinary claims require extraordinary evidence.”

Within a couple of months, the attacks were ramping up.  Edward Anders from the University of Chicago wrote this:

David S McKay et al. deserve praise for discovering possible evidence of past Martian life. The identification of indigenous organic compounds in a Martian meteorite alone is a breakthrough, reopening the possibility of life after the chill cast by Viking. The characterization of the carbonate globules sets a new standard for study of extraterrestrial materials.

After this polite opening, he gets down to the business of attacking the original paper. He concludes with this:

McKay et al. conclude their paper by listing five lines of evidence and then stating:

None of these observations is in itself conclusive for the existence of past life. Although there are alternative explanations for each of these phenomena taken individually, particularly in view of their spatial association, we conclude that they are evidence for primitive life on early Mars.

For all these observation, an inorganic explanation is at least equally plausible, and, by Occam’s Razor, preferable. Consistency arguments alone – weak consistency arguments especially – cannot strengthen, let alone prove, an extraordinary conclusion.

This wasn’t a case where a few strange results appear and are ignored until there’s enough of them that a crisis happens; the controversy existed in its full form right from day 1.