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The thick icy crust of Europa, a moon of Jupiter, hides a deep ocean. Scientists hope to penetrate the crust with a powerful “melt probe” and reach the subsurface ocean. Underwater, a “hydrobot” would collect information and send it to Earth.
What type of life do we expect beyond our planet? Most of Earth’s life is microbial and is found in our oceans. Several moons in our Solar System contain deep oceans and have strong potential for habitability. Life could exist in these subsurface oceans, perhaps in an environment similar to Earth’s deep-ocean hydrothermal vents or the Antarctic subglacial Lake Vostok.
SATURN’S MYSTERIOUS MOON, ENCELADUS: In 2005, scientists using NASA-ESA’s Cassini spacecraft detected plumes of water vapor and organic gases above Enceladus’ south pole, suggesting that a deep liquid ocean lies beneath its icy surface. The Goddard-built and -managed infrared spectrometer on Cassini discovered warm temperatures in the vents that release these plumes.
The iconic globe of Mars, with surface relief exaggerated ten-fold. Mars is similar to Earth, with icy polar caps, an atmosphere, and a surface marked with deep canyons and enormous volcanoes. But on Mars, water is scarce and the atmosphere is thin. The symbols on the globe identify the locations of the NASA rovers: Curiosity (square), Spirit (triangle) and Opportunity (circle).
METHANE RELEASES ON MARS: In 2003, Goddard scientists detected methane on Mars. On Earth, methane is an indicator of biology and geology, and these observations may point to habitable regions on Mars, or active geological areas. On Mars, methane was found in large plumes (red, above).
The search for life (existing or extinct) has been a driving theme in exploration, giving rise to several NASA missions and to sensitive searches for gases related to biology. Mars is one of a select few Solar System bodies where life might have evolved and perhaps might survive in favorable niches even today.
CURIOSITY SELF-PORTRAIT: Goddard scientists search for methane and other organics on Mars with the Curiosity rover, the most powerful lander ever to operate on the surface of Mars.
Mars’ signature color (red) originates in a cover of rust, a deep layer of dusty iron-oxide covering much of its surface. Mars is also blanketed with many other minerals including some that formed in water, indicative of a wet past.
Life controls Earth’s atmosphere. Oxygen and carbon dioxide are produced by life, but so are many less abundant gases. Methane, ammonia and nitrous oxide are produced mainly by biological processes. Without life, our atmosphere would have a very different composition. That is why scientists seek “biomarker” gases on Mars and exoplanets.