There’s been news lately about some methane spikes that have been detected in the atmosphere of Mars. Since Mars’s atmosphere destroys methane, this is a little puzzling. Although methane can be produced by geologic activity, on Earth one of the biggest producers of methane is life.
“Miss, are there aliens?” was probably the most frequently asked question in the Planetarium at the University of Guam and given the number of stars and galaxies we’ve detected, the answer is definitely “Yes,” but all those stars and galaxies are too far away for it to get here.
But Mars is close and there are several other candidates for life in our own solar system. Scientists are reexamining data from an old mission to bring new insights to the question of whether Jupiter's moon, Europa, could support life. The data provide independent evidence that the moon's subsurface liquid water reservoir may be venting plumes of water vapor above its icy shell.
Data collected by NASA's Galileo spacecraft in 1997 were put through advanced computer models to try to explain a brief, localized bend in Europa’s magnetic field. Previous ultraviolet images from NASA's Hubble Space Telescope in 2012 suggested the presence of plumes, but this new analysis using data collected much closer to the source is considered strong, corroborating evidence for Europa plumes.
At the time of the 1997 flyby, the Galileo team didn't suspect the spacecraft might be grazing a plume erupting from the icy moon. Scientists had learned from exploring plumes on Saturn's moon Enceladus, that material in plumes becomes ionized and leaves a characteristic blip in the magnetic field. And the same thing apparently happens on Europa.
But Mars, Europa and Enceladus may not be the only places for life in the solar system. In addition to some of the other moons of Jupiter and Saturn, scientists are dusting off an old idea that considers a new location in the hunt for life beyond Earth: the clouds of Venus.
Venus had plenty of time to evolve life. Some models suggest Venus once had a habitable climate with liquid water on its surface for as long as 2 billion years which is much longer than is believed to have occurred on Mars.
On Earth, terrestrial microorganisms like bacteria are swept into the atmosphere, where they have been found alive at altitudes as high as 25 miles. Microbes also inhabit incredibly harsh environments on Earth, including the hot springs of Yellowstone, deep ocean hydrothermal vents, the toxic sludge of polluted areas, and in acidic lakes.
Here on Earth, life can thrive in very acidic conditions, feed on carbon dioxide, and produce sulfuric acid. The cloudy, highly reflective and acidic atmosphere of Venus is composed mostly of carbon dioxide and water droplets containing sulfuric acid.
Several space probes that have orbited Venus found the temperature and pressure conditions in the lower and middle portions of its atmosphere could support microbial life. There are also Earth bacteria with light-absorbing properties that could explain dark patches observed in the Venusian clouds. Spectroscopic observations, particularly in the ultraviolet, show the dark patches are composed of concentrated sulfuric acid and other unknown light-absorbing particles.
And of course, scientists are looking for life-as-we-know-it. But what if there are other kinds of life? What if it isn’t carbon-based? What if it’s based on energy and not matter? The aliens are out there. We just may not recognize them as alive when we find them!