The discussion explores how a massive impact blasted the rock from Mars roughly 16 million years ago, sending it on a long journey through space before crashing into Antarctica. Levison raises the tantalizing speculation that Mars and Earth may have been swapping microbial material for billions of years, meaning life on Earth could have Martian origins. He also addresses Europa, calling it the most likely place in the solar system to find life, with its probable liquid ocean heated by Jupiter's tidal forces.
Levison balances excitement with characteristic scientific caution, noting that extraordinary claims require extraordinary proof. He emphasizes that three Mars missions launching later that year could dramatically advance understanding, while acknowledging that even the Cydonia formations will be re-imaged by the Mars Global Surveyor.
Key Moments
Chemical fingerprinting ties ALH84001 to Mars: Levison explains the scientific basis for declaring the meteorite Martian: each visited planet has a unique chemical fingerprint, and ALH84001's signature matches Mars - confirmed by direct atmospheric and rock measurements from Earth, Moon, and Mars.
Carbon isotope anomaly first flagged by Arizona team: Levison reveals the carbon isotope ratios in ALH84001 don't match other Martian meteorites - an anomaly noticed years earlier by a University of Arizona group, who pointed out that life is one mechanism that can alter carbon fingerprints.
Asteroid-belt meteorites used as negative controls: Levison details the control test: NASA's team ran the same analysis on meteorites known to come from the asteroid belt, of varying ages and similar Earth-impact histories, and every one came back negative for the organic signatures found in ALH84001.
Source crater on Mars identified: A press release from Dr. Nadine Barlow at the University of Central Florida arrives live on air: she has identified two likely source craters on Mars for ALH84001 by cross-referencing the meteorite's 4.5-billion-year formation age and 16-million-year ejection date against her crater catalog from Arizona.
Burned crust ruled out terrestrial contamination: Levison explains how the team ruled out Earth contamination: the meteorite's burned outer crust contained none of the organic signatures, which were only present deep inside the rock - the entry-heat had destroyed any surface materials it might have picked up.