Past satellite and robotic missions have documented Mars' many river valleys and lake beds, revealing a landscape carved by an ancient and active water cycle. But today, Mars is very dry, and if a new study is correct, the planet's size itself appears to be to blame.
See also: Journey to Mars: When can humans travel safely?
See also: Mars: Earth-like clouds pass over its surface
Wang, the senior author of a new study led by graduate student Zhen Tian and published this week in the Proceedings of the National Academy of Sciences, examined stable potassium isotopes in several meteorites whose origins are known to approximate the presence, levels, and distribution of volatiles that can be a tracer of the amount of water present.
By analyzing the composition of Earth along with meteorites from Mars, the moon, and the asteroid 4-Vesta, the study authors found a well-correlated relationship between the size of a body and the abundance of this particular potassium isotope.
Furthermore, the 20 Martian meteorites – ranging in age from 200 million years to 4 billion years – revealed that Mars lost its volatiles, including water, at a much faster rate than Earth did in the first billion years of its formation.
According to some models, Mars in its early formation would have been remarkably similar to Earth, including a thick Earth-like atmosphere and stagnant water on surface .
Mars lost its protective magnetic field and the ravages of solar winds stripped away much of its atmosphere and evaporated all water about a billion years after its formation.
See also: Mars: Does it hide an ocean beneath its surface?
Analysis: What does this mean for the search for extraterrestrial life?
The new study offers an important insight into the search for extraterrestrial life. While we have found thousands of exoplanets orbiting alien stars, determining which ones are good candidates to host life is a challenge.
Studying all of these is currently impossible, and many can be ruled out from some of the data we already know. We can largely rule out planets that don't orbit within the star's "habitable zone," the theoretical zone around a star where liquid water could exist on the surface of a planetary body. But both Venus and Mars exist within our sun's habitable zone, and they are currently both inhospitable to life.
This new study could add another important filter to our exoplanet data to narrow down potential candidates for study, Wang said.
"The size of an exoplanet is one of the parameters that is easiest to determine. Based on size and mass, we now know whether an exoplanet is a candidate for life, because the first-order determinant of volatile capture is size.".
Information source: techradar.com
