A small meteorite made international headlines in 1996 when scientists discovered it might contain evidence of life on Mars, but now a study from a University of Houston graduate student could debunk that claim.

The research published by Mary Sue Bell, who just completed her Ph.D. in geology this summer, is a major finding that has caught the attention of planetary scientists and deflated hopes of finding little green men.

Bell’s Ph.D. research project centered on ALH 84001, a famous Martian meteorite found in Antarctica more than two decades ago. This potato-sized chunk of Mars, estimated to be almost 4 billion years old, made its way to Earth when a meteor slammed into the Red Planet, sending little pieces of Mars out into space.

In 1996 the rock sparked an international sensation when NASA scientists claimed that magnetite crystals on the meteor could be fossilized remains of tiny bacteria. It was believed to be the first real evidence of extraterrestrial life and even prompted an official announcement from then-President Bill Clinton.

However, Bell’s re-creation of those magnetite crystals in a lab dealt a major blow to that theory. Bell, a planetary scientist at NASA while working on her Ph.D. part time, used a powerful canon-like instrument at the Johnson Space Center to simulate a meteorite impact.

Bell fired a small projectile into a target of siderite – an iron carbonate rock – at a speed of nearly 1.5 kilometers per second and at a pressure of 49 gigapascals. This simulates the force of the meteor that struck Mars, sending Martians rocks flying to Earth.

The shockwaves passing through the siderite in the lab caused instantaneous chemical reactions that created magnetite crystals identical to those found on the Martian meteorite, Bell said.

“There’s only one thing we know for sure about this meteorite – that it was shocked by impact,” Bell said. “Using the one process we know occurred, we’ve created magnetite crystals indistinguishable from the crystals in the (Martian) meteorite.”

The shock from the impact is a more likely explanation for the magnetite crystals on the meteorite than any biogenic process, Bell said.

Bell published her findings in 2007 in the journal Meteoritics and Planetary Science and learned in July she had received this year’s Nininger Meteorite Award, an honor given by the Arizona State University Center for Meteorite Studies. The award recognizes the most outstanding meteorite research by young scientists and includes a $1,000 prize.

The debate swirling around the origins of the magnetite crystals in the Martian rock has been a contentious one, Bell said. And while growing evidence suggests those crystals are not the fossilized remains of Marian life, there are still other signs that there might have been life on Mars in the past. Data collected by the Phoenix Mars Lander indicates there is likely water ice in the shallow subsurface at the landing site, Bell said.

Bell will continue her meteorite research at NASA, where she has worked since 1994, curating meteorite samples collected by NASA teams in Antarctica. It was a NASA team that discovered the ALH 84001 meteorite in 1984, and Bell was sent on a similar meteorite-hunting expedition in 2005.

For six weeks she and her team camped out on the Antarctic ice, traveling by snowmobile and recovering more than 100 meteorites ranging in size from a dust flake to a softball.

Meteorites are easier to spot in the white snow and ice of Antarctica, Bell said.