“If there’s life or past life on Mars, it means the chances that life exists somewhere else are much higher,” said David Paige, who studies the moon and terrestrial planets at UCLA. If Mars is barren, “it might make Earth more unique than we thought.”
Some experts question the wisdom of focusing so intently on a single planet. Jupiter’s moon Europa, which is covered with an ice-encrusted ocean, could have the potential to harbor life; Saturn’s moon Titan, rich in organic chemistry, might as well.
“It’s like the person who loses their keys and only looks for them below the streetlight,” said David Jewitt, a planetary scientist at UCLA who studies comets.
But funds for planetary science are limited — and even those who favor a broader search admit that Mars remains the most practical site to explore.
A mission to Europa, for example, would take about six years to reach its destination. Curiosity’s trip to Mars takes about eight months.
Europa has other drawbacks too: For one, particles flung into space by Jupiter’s magnetic field would likely fry a spacecraft’s electronics in a matter of weeks, said Richard Greenberg, who studies the frozen moon at the University of Arizona.
“Personally, I love Europa,” he said. “But objectively, both it and Mars are great places to look for life.”