Much was made of NASA's announcement last month that "building blocks of life" had been found on Mars. But new research suggests the same organic molecules may actually have been discovered by Viking landers NASA sent to Mars in 1976—and then accidentally burned, New Scientist reports. The landers' main instrument was a gas chromatograph-mass spectrometer, which used heat in an attempt to find organic matter. But scientists now know that due to a chemical in the soil on Mars, that process would have destroyed anything organic. At the time, scientists were "shocked" when the Viking landers reported finding nothing organic, USA Today reports.
"It was just completely unexpected and inconsistent with what we knew," a NASA scientist explains, per Space.com. Small, carbon-rich meteorites frequently hit Mars, so researchers had long assumed there would be organic matter on the planet. When scientists discovered perchlorate, a salt that's explosive under high temperatures, in Mars soil, they realized what might have happened during the 1976 mission. The new study corroborates the idea of the Viking landers possibly discovering and then destroying organic matter, but it doesn't conclusively prove it. (Read more Mars stories.)