25 years after the magazine featured a story about life on Mars, we’re still searching — but recent science sheds light on what we could find.
Aliens have been the darling of human imagination since ancient times. From Christiaan Huygens’ hemp-growing sailors and musicians to Marvel’s trees and racoons, visions of alien life over the years have been as diverse as their creators.
All these conjectures are just guesswork, of course. Over the years, countless people and publications have speculated on alien life, this magazine included. “Life on Mars,” a 1999 article about the possibility of life in Mars’s past written by Lynn Weinberger, investigated the contemporary research into alien life and shows how far our understanding has come in the 25 years since.
Weinberger’s article was published shortly after the discovery of the meteorite ALH84001, thought to have come from the Red Planet. Weinberger excitedly wrote about how the meteorite contained organic molecules and microscopic nodules in the shape of cells. To Weinberger and contemporary scientists, these chemicals and nodules were “evidence of fossilized organisms,” 100 times smaller than cyanobacteria.
Nowadays, we know the disappointing truth: those nodules were not relics of alien life. According to Dr. Eric Roden, a professor of geoscience who teaches the university’s Life in the Universe course, the small size of the “cells” was the smoking gun proving they weren’t biological structures.
“If you found life on another planet within our solar system… that would be a complete game-changer.”
Eric Roden
“The problem is that the structures that were in the meteorite… were too small to allow for sufficient DNA to be in the cell in order to code for the most basic cellular functions,” Roden explains.
Though convinced life existed in Mars’s past, Weinberger dismissed the possibility of it still existing in modern times, writing “[Mars] can no longer support life.” This opinion is common among modern astrophysicists, including Alyssa Jankowski, a postbaccalaureate exoplanet researcher for the Department of Astronomy.
“A lot of factors go against Mars in terms of habitability,” Jankowski explains. “It lost a lot of its water… it has a weaker magnetic field… it’s far, far colder than Earth is.” However, given the extreme environments life can thrive in on Earth, it’s possible that microbes could exist deep below the Red Planet’s soil, shielded from the cold and radiation.
There’s evidence to support this possibility: In 2011, undergraduate researcher Lujendra Ohja discovered liquid water seeping upwards from below Mars’s surface, suggesting there may be veins of water capable of supporting life underground. Moreover, microbes could explain the presence of methane in Mars’s atmosphere – but this argument is hardly airtight.
Unfortunately, like all questions about alien life, these mysteries will remain unanswered for the foreseeable future. “Until there’s a drilling campaign on Mars, we won’t know,” Roden says. “My gut reaction is we’re a couple hundred years away.”
The prospects may look grim, but as Weinberger wrote, “[even] the slight possibility of life on other planets [will motivate scientists] to continue their research.” It’s too interesting a field to abandon.
For now, the search for alien life has turned to other places in the Solar System, and beyond. “The names that I’ve heard most frequently are Titan, Europa, and Enceladus,” Jankowski says. These moons of Saturn and Jupiter might have water oceans beneath their surfaces, far better environments for alien life than the dry plains of Mars.
As Roden proclaims, “If you found life on another planet within our solar system… that would be a complete game-changer.” If life occurred twice in our own solar system, who knows how common it could be across the cosmos? This tantalizing question is sure to motivate researchers for decades – if not centuries – to come.