ALH84001 + 10
by Jeff Foust
|At the moment it seemed that we were witnessing history: the discovery of evidence of life on another world had to be one of the most profound scientific discoveries of recent times, if not ever.|
It was. A short time later NASA issued a formal statement by administrator Dan Goldin confirming that, in his words, “NASA has made a startling discovery that points to the possibility that a primitive form of microscopic life may have existed on Mars more than three billion years ago.” What followed the next day was a media circus as scientists described how a Martian meteorite with the ungainly designation of ALH84001 (sometimes simply called “Allan Hills” after the region in Antarctica where the meteorite was discovered in 1984) contained evidence of ancient microbial life on the Red Planet. The event attracted the world’s attention, and even prompted comments by President Clinton, who called the discovery “another vindication of America’s space program and our continuing support for it, even in these tough financial times.”
At the moment it seemed that we were witnessing history: the discovery of evidence of life on another world, even the simplest organisms that dated back more than three billion years, had to be one of the most profound scientific discoveries of recent times, if not ever. Even with all the caveats made during the announcement—the need to independently verify the discovery, the now-famous quip that “extraordinary claims require extraordinary evidence”—the results seemed very compelling to many in the space field, not to mention the general public.
Then a funny thing happened: the caveats grew larger. In the following months and years other scientists examined ALH84001 and the evidence for Martian biology, and many came to alternative conclusions. As the initial announcement faded from public memory, a growing number of researchers argued that the evidence announced at that press conference (and published shortly thereafter in the peer-reviewed journal Science) could have abiogenic origins—that is, the chemicals and “microfossils” found in it could have been created by processes other than the life and death of microorganisms. Scientists involved with the original discovery, meanwhile, still believe that the meteorite holds evidence of Martian life and continue to study it. “We certainly have not convinced the community, and that’s been a little bit disappointing,” David McKay, the lead author of the original Science paper, told the Associated Press recently.
So, at the ten-year anniversary of the original announcement, the case that ALH84001 contains evidence of past Martian life seems inconclusive at best, and outright discredited at worst. Little wonder, then, that the anniversary of what seemed like a historic event ten years ago is getting so little attention today. Other than the AP article mentioned above and similar pieces by the Houston Chronicle and the British newspaper The Guardian, the media has ignored the anniversary. Similarly, at the just-completed Ninth Annual International Mars Society Conference, held at a Washington, DC hotel just a few blocks from NASA Headquarters, there was virtually no mention of the discovery or its effect on Mars exploration plans or society in general throughout the four-day conference. It was almost as if the discovery had never been made.
Yet, even if ALH84001 turns out to be nothing more than a Martian rock with some curious features, what is inarguable is that it has had a significant effect on Mars exploration and research. The discovery came at a time when NASA was starting a new generation of Mars missions: the first of those missions, Mars Global Surveyor and Mars Pathfinder, were launched a few months after the ALH84001 announcement. The discovery gave those missions more attention; their successes—Pathfinder in particular—in turn helped sustain and grow public interest in Mars exploration.
|“Mars became much more real,” Zubrin said. “I think there was a revolution in people’s views of Mars and the general level of attention paid to Mars as a result of Allan Hills, Pathfinder, and my own book.”|
The discovery also arguably reshaped the robotic exploration program into one that focused more on whether Mars might have once supported life: the now-familiar “follow the water” strategy incorporated into several recent NASA missions. “I think it [ALH84001] caused a significant redirection of the NASA robotic Mars program in the direction of astrobiology,” Robert Zubrin, president of the Mars Society, said in an interview at the end of the Mars Society conference Sunday. “I’d go to meetings of the Mars science working group in the early 90s and they’re looking at seismology and networked meteorology, and people interested in looking for life on Mars were viewed as like grad students who never grew up. At this point, I think the search for life on Mars is viewed as the mainstream subject of what the robotic Mars program is about.”
ALH84001 also helped raise the profile of astrobiology in general, helping it emerge as a distinct scientific discipline in the last decade. “In 1996, you couldn’t find a university class in astrobiology,” Everett Gibson, one of the members of the original ALH84001 team, told the Chronicle. “Now major universities are granting doctorates in it.”
The discovery also had an effect on the space advocacy movement. Around the time of the announcement Zubrin and Richard Wagner published the book The Case for Mars, describing both the importance of human exploration of the Red Planet and Zubrin’s “Mars Direct” proposal for mounting such a mission at a far lower cost than previous NASA concepts. The strong outpouring of interest in the book—Zubrin said he received 4,000 letters from readers wanting to know how they could help make a manned Mars mission a reality—led him to establish the Mars Society in 1998. Had there not been a surge of interest in Mars created by the ALH84001 announcement, would there even be a Mars Society today?
“I don’t know,” Zubrin said. “I think there might be; it’s hard to say.” He said while there was “no question” that the discovery increased sales in the book, perhaps doubling the number of copies sold, he thought there would have still been significant interest in the book without ALH84001. “If not for Allan Hills, maybe I would have gotten 2,000 letters.”
Zubrin credits the confluence of the ALH84001 announcement, his book, and the later landing of Pathfinder for creating a “crest” of interest in Mars among the general public. “Mars became much more real,” he said. “I think there was a revolution in people’s views of Mars and the general level of attention paid to Mars as a result of Allan Hills, Pathfinder, and my own book.”
Zubrin saw some parallels between ALH84001 and claims of the discovery of canals on Mars a century ago in the sense of raising public awareness about the prospects for life on Mars, although he was careful to point out that while the existence of the canals had long since been disproven, he still thought that biogenic processes were the most likely explanation for the features seen in the meteorite. “It all of a sudden re-raised the whole issue of life on Mars in a very direct way,” he said. “I think Allan Hills was pretty important.”
Despite the scientific uncertainty and skepticism about the evidence for life contained within ALH84001, the announcement and its reaction has had a clear long-term effect on Mars science, exploration, and advocacy. One can even argue that, without it, Mars might not have a role in the Vision for Space Exploration: the interest in Mars exploration built up and sustained since 1996 made it logical to include human exploration of Mars in the new national space policy, albeit as a distant, ill-defined goal. Recall that, despite Clinton’s glowing praise for NASA at the time of the ALH84001 announcement, his administration released a national space policy document a little over a month later that limited human space activities to Earth orbit.
|One can even argue that, without ALH84001, Mars might not have a role in the Vision for Space Exploration: the interest in Mars exploration built up and sustained since 1996 made it logical to include human exploration of Mars in the new national space policy, albeit as a distant, ill-defined goal.|
However, whatever influence the AH84001 announcement and its aftermath had may be fading. The pace of robotic Mars exploration has slowed down from the plans of the latter half of the 1990s: while at that time there were proposals for a sample return mission by 2005, such a mission has been pushed back to the indefinite future. NASA-funded astrobiology research, Mars-related or otherwise, has also taken a hit in the 2007 budget proposal, something that NASA administrator Michael Griffin defended in a speech at the Mars Society conference on Thursday. “We are not being asked, at the present, to do astrobiology or a huge amount of biology work of any type,” he said.
Even the memory of ALH84001 itself is beginning to fade. After I concluded my interview with Zubrin, a conference attendee who was listening in asked me what this “Allan Hills” we were talking about was. “Is it a location on Mars?” he asked. I explained it was a reference to ALH84001, the famous Martian meteorite. “You know, the one that was in the news ten years ago,” I said. He nodded, but there wasn’t the flash of recognition on his face that you expect to see when a person really remembers something. Nonetheless, if ALH84001 slides back into obscurity, it will still have had a profound impact on how we view—and explore—Mars.