Move Over Mars -
Europa Needs
Equal Billing
By Leonard David
Washington Contributing Editor
Europa, a moon of Jupiter, appears to have vast quantities of liquid water below its icy surface, making this world a top candidate in the search for exobiology -- life beyond Earth -- a scientific panel reported today.
The National Research Council (NRC), an advisory arm to the nation on science, released today its report: "A Science Strategy for the Exploration of Europa." It recommends to NASA that Europa be given equal priority to future exploration of Mars.
The NRC's Committee on Planetary and Lunar Exploration (COMPEX) issued the scientific report. Ronald Greeley, chair of COMPLEX, told that "the potential for understanding environments that can support life is high on Europa. In some respects, Europa could be a better target for exobiology than Mars," he said.
Greeley said Europa is believed to sport an internal heat source, primarily driven by the gravitational push and pull on the moon -- called tidal effects -- as the world circles gigantic Jupiter. "In contrast, we don't know about any internal heat generated on Mars," he said.
According to the NRC report, Europa may contain a global ocean of liquid water more than 62-miles thick and covered by only a thin layer of water ice. And where there is heat and water, the odds for life taking hold should skyrocket.
"As a result of the likely existence of liquid water, at least on a transient or intermittent basis, Europa has the potential for life to exist below its surface," the report says.
Now on duty around Jupiter is the Galileo spacecraft. Dispatched from the space shuttle Atlantis in October 1989, Galileo has been studying Jupiter and several of its moons for nearly four years.
Just last October 11, Galileo slipped by another moon of Jupiter, volcano-laden Io. A similar flyby of Io by the probe is slated for the end of this month. But during this encounter, Galileo is also slated to snap photos of Europa from a perspective never viewed before, Greeley said.
What next for Europa?
"Our report outlines a rationale to search for life on Europa and details the kinds of measurements to address the question of life on Europa through a series of missions," Greeley said.
The NRC report recommends the need for a step-by-step program of exploration. Work is already underway on a Europa orbiter spacecraft at the Jet Propulsion Laboratory in Pasadena, California. That mission should determine whether a global ocean of liquid water exists beneath Europa's icy exterior.
Follow-on work at Europa, the NRC report urges, should focus on first landing a package of instruments on the Jovian moon. If subsurface liquid water is detected, and can be breached, an instrumented probe to scout for life in the liquid water should then receive priority, the NRC study concludes.