The American and European space agencies have come to an agreement on a long-term plan to explore the moons of Jupiter. A competing scheme to visit the moons of Saturn was set aside temporarily to make way for the Jovian exploration.
In a statement released yesterday, NASA said that its representatives and those of the European Space Agency (ESA) had decided to move forward on planning for a pair of missions to the Jupiter system to be launched in 2020.
The Americans would send a craft to ultimately investigate the moon Europa, which scientists believe is covered in liquid water beneath an icy exterior. The European probe would eventually explore Ganymede, the largest moon in the solar system, which may also have a subsurface ocean.
Both missions, to take place simultaneously, would take six years to reach Jupiter; then they would begin about two years of sailing through the Jovian system, inspecting a variety of moons before settling into orbits around their respective final targets.
The twin missions have not been approved by the governments that operate the two space agencies, and the missions' budgets have not been determined. But experts have put a price of between US $2.5 to $3 billion on the overall plan, according to media reports.
The joint statement stated that these 'outer planet flagship missions could eventually answer questions about how our solar system formed and whether life exists elsewhere in the universe'. It noted that the proposed space flights, known together as the Europa Jupiter System Mission, were the result of a great deal of research by NASA and ESA engineers and scientists under the umbrella of a joint working group. And it added that much more detailed studies will be required before the plan officially moves forward.
The decision to favor Jupiter with attention first, however, should not be seen as a snub to those who had pushed for missions to Saturn's moons, which also have distinctly interesting scientific characteristics, a leading NASA official observed.
"The decision means a win-win situation for all parties involved," said Ed Weiler, associate administrator for NASA's Science Mission Directorate in Washington. "Although the Jupiter system mission has been chosen to proceed to an earlier flight opportunity, a Saturn system mission clearly remains a high priority for the science community."
A spokesperson for ESA stated that the joint endeavor could be a "landmark of 21st-century planetary science."
"What I am especially sure of is that the cooperation across the Atlantic that we have had so far and we see in the future, between America and Europe, NASA and ESA, and in our respective science communities is absolutely right," said David Southwood, ESA Director of Science and Robotic Exploration. "Let's get to work."