The Sciences

New Life Found on an Old Rock

How a humble meteorite redefined the future of astrobiology.

By Elise CuttsFeb 18, 2023 12:00 AM
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Discovered in 1984, the Mars rock known as ALH84001 was eventually found to contain carbonates — a possible sign of life once existing on another world. The press went wild and ALH84001 became a literal rock star (Credit: NASA).


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In 1995, NASA was strapped for cash — and the search for life beyond Earth looked like it could be in trouble.

Years of steep cuts had reduced the space agency’s five-year budget plan by just over 30 percent. Interest in exobiology — the study of the origins, evolution, and distribution of life in the universe — had been drying up for decades. After the 1976 Viking lander’s life-seeking experiment on Mars came up empty, NASA cut down on Mars missions. Congress canceled NASA’s Search for Extraterrestrial Intelligence program in 1993, after less than a year of operation. And in 1995, the Clinton administration called for more than $5 billion in additional reductions to NASA funding before the new millennium.

“Then a miracle happened called ALH84001,” says Wesley Huntress, then NASA’s associate administrator for space science. “And that just galvanized the public interest in what we were doing.”

A potato-sized lump of 4-billion-year-old, grayish-green rock from Mars, ALH84001 fell to Earth some 13,000 years ago. Researchers found it in the Allan Hills region of Antarctica on a meteorite-hunting expedition in 1984, and brought to the Meteorite Processing Laboratory of the Johnson Space Center (JSC), where the rock’s martian origin was discovered almost a decade later in 1993.

ALH84001 isn’t just any martian meteorite. It contains carbonate minerals — minerals that, on Earth, can form due to life — which JSC researchers thought had grown at habitable temperatures. Under an electron microscope, tiny structures in the carbonates looked like images of nanobacteria entombed in a hot spring mineral deposit on Earth. These carbonates weren’t enough to prove anything on their own, but they hinted that ALH84001 might be far more than just another space rock. So, in 1994, a JSC-led team quietly got to work taking a closer look at the meteorite.

(Credit: NASA)

Revived search

Two years later, on Aug. 7, 1996, NASA announced that JSC’s researchers believed that ALH84001 contained traces of ancient microbial life from Mars.

Suddenly, the search for life was back on. That same day, President Bill Clinton went on TV to promise that NASA would “put its full intellectual power and technological prowess behind the search for further evidence of life on Mars.” A few days later, a headline reading “After Mars Rock, a Revived Hunt for Otherworldly Organisms” topped the science section of the New York Times. By September, NASA’s Ames Research Center had brought together nearly 100 astronomers, earth scientists, and biologists for the first-ever scientific conference in astrobiology, the successor to exobiology, encompassing a broader view of the search for life in the universe. And in December, Vice President Al Gore met with leading scholars to discuss the implications of finding evidence of alien life, and to chart a course for NASA’s future exploration of Mars.

Astrobiologist Jamie Foster of the University of Florida was watching as these events unfolded. A young Ph.D. student at the University of Hawai’i in 1996, Foster had always dreamed of working for NASA, but was instead working at a zoology lab when ALH84001 hit the news.

“I remember President Clinton at the time going on TV and talking about this rock — you know, talking about the exciting potential: Has life from Mars been discovered in this meteorite?” says Foster. “Now we know that it’s very, very debatable, … but what it did do was it allowed the appropriation of funding.”

Traveling from Mars 13,000 years ago, ALH84001 landed in Antarctica’s Allan Hills (Credit: tunasalmon/Shutterstock).

Embracing astrobiology

Early on, it was clear that the meteorite would have financial stakes. Huntress recalls getting a call, shortly after ALH84001 hit the headlines, from Steve Isakowitz, then the space programs branch chief of the White House’s Office of Management and Budget. Isakowitz wanted to know how NASA should capitalize on the discovery. “The president’s Office of Management and Budget came around and said, ‘What do you want to do about this Mars rock?’ ” says Huntress. “We had a plan right in our back pocket, called Origins.”

An “Origins” program had been under development since at least 1994. The idea was to unite many of NASA’s myriad space science missions behind one grand unifying theme: understanding the origin, distribution, and future of life in the universe. Before ALH84001, Origins “was just a plan,” says Huntress. But after much back and forth between Isakowitz and Huntress, it became much more.

The president’s fiscal year 1998 NASA budget proposal called for a staggering $1.5 billion more funding for space science between 1998 and 2000 compared to the 1996 proposal. Plans for additional, steep, billion-dollar cuts to NASA’s overall budget through 2000 were scrapped; NASA’s budget would still shrink slightly, but space science, and above all, astrobiology, was looking at a renaissance. 

Citing the discovery of putative biosignatures in ALH84001 as a motivation for the new funding, the 1998 budget allowed for cash infusions for the search for life. It funded new exoplanet-finding missions, including the Next Generation Space Telescope — eventually renamed the James Webb Space Telescope — that launched in December 2021. It also earmarked money for a new program in developing technologies for exploring the solar system, and boosted funding for the Mars Surveyor program with the goal of one day returning a sample from Mars — a mission the Perseverance rover is carrying out today.

Origins also funded a new program in astrobiology that became the Ames-led NASA Astrobiology Institute (NAI). Enjoying the flush of new funding for and the growing scientific legitimacy of astrobiology, NASA welcomed biologists to space science with new enthusiasm.

Foster was one of those biologists. More than 20 years later, she is a professor at the University of Florida Space Life Science Lab, where she studies modern-day analogues of microbial ecosystems that were common on the early Earth, and how spaceflight impacts animals and their microbiomes.

For her, the sudden rise of funding, institutional support, and interest in astrobiology made it possible to pursue a career that would have been nearly impossible just a few years earlier. “The meteorite created doors that never existed before,” she says.

ALH84001 was not the only factor that pushed NASA to embrace astrobiology in the mid-1990s. “It was the union of many things at the same time, creating a perfect storm for the study of life in the universe,” says Lynn Harper, who was co-lead for astrobiology at Ames between 1995 and 2003. “The Allan Hills meteorite by itself did not secure the funding [for the NAI],” she says. It “was certainly in the mix. But it would not have been enough.”

Harper sees an aggressive internal audit called the Zero Base Review as having been more important to the development of astrobiology at NASA. The Zero Base Review was launched in 1995 in response to NASA’s dramatically shrinking budget, as a way to either eliminate or restructure inefficient programs. The space agency needed to trim down and Ames — long host to an unusual interdisciplinary cadre of respected exobiologists — found its science programs on the chopping block.

Today, the Perseverance rover carries on the search for evidence of life on Mars (CC BY-SA 3.0 IGO; NASA/JPL-Caltech).

Unlike other NASA centers such as the Jet Propulsion Laboratory, which leads NASA in planetary science, Ames’ mix of researchers, who studied everything from planetary atmospheres to life in extreme environments, made their roles at NASA hard to pin down. But Ames’ leadership knew their exobiology hot spot was something worth saving. So instead of putting together the going-out-of-business plan they’d been asked for, they argued that the center really did serve several purposes, including the search for life in the universe and understanding how life originates. It worked, which was why Ames ultimately became NASA’s lead center for astrobiology.

And ALH84001 was not the only discovery of the 1990s to rekindle interest in the search for life. Hubble began sending back dazzling images of space in 1990. The first exoplanet was found in 1992, and the Galileo probe’s flybys of Europa beginning in 1996 hinted that the icy moon could harbor an ocean. Some of these findings are highlighted alongside ALH84001 in the budget request that funded Origins.

Today, the scientific community mostly agrees that the possible biosignatures in ALH84001 aren’t all that convincing. Even in 1996, researchers voiced skepticism of the findings. “The Mars rock” was one of the greatest scientific discoveries that never happened. Nevertheless, that rock reinvigorated NASA’s search for life, still ongoing today.

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