January 22, 2009
Proposals Compete For Joint Space Mission
U.S. and European space officials are considering proposals to send probes to the outer planets of the solar system.
One ambitious plan would send an orbiter to Saturn which would release a lander to the moon Titan.
Another plan hopes to see two orbiters sent to Jupiter and to its moons, Europa and Ganymede.
In February, Ed Weiler of NASA, and David Southwood of the ESA, will announce which plan will go forward to be discussed more thoroughly.
The mission could cost billions of dollars to complete, and would not be launched before 2020. Potentially, the mission could never reach orbit if the space agencies deem it lower priority than other missions.
ESA published reports from the two competing definition teams this week.
The reports provide in-depth descriptions of each mission's goals and defined the amount of participation needed from NASA and ESA.
The Titan Saturn System Mission (TSSM) would be a follow up to the successful Cassini-Huygens mission which still is in operation around Saturn.
The plan foresees another orbiter being sent to Titan and Enceladus, two of Saturn's moons.
The Cassini mission sent back data indicating that Titan held many similarities to a frozen Earth, such as its thick atmosphere, and its wealth of carbon-rich molecules.
Enceladus also appears to have an ocean of liquid water beneath its service. Data from the Cassini mission showed hot spots near the moon's southern pole that released jets of water-ice into space.
The TSSM orbiter would dive into Titan's atmosphere to drop a lander, and to sample the air. Then the orbiter would pass by Enceladus to try and discover the chemical makeup of its water-ice plumes.
The other competing mission, the Europa Jupiter System Mission (EJSM), plans to target the Galilean moons, Europa and Ganymede.
Europa has been at the top of scientists' wish-list for a while due to its cracked surface that could potentially hide a sub-glacial ocean.
The EJSM team hopes to see Europe and the U.S. focus on one moon each. NASA would send the Jupiter Europa Orbiter (JEO), and ESA would send the Jupiter Ganymede Orbiter (JGO).
The JEO spacecraft would need specific shielding to protect against Europa's severe radiation environment.
Both orbiters would end their missions in a blaze of glory, by crashing into their particular moon.
The ideas for the missions have been born out of several years of discussion by NASA's Outer Planets Assessment Group (Opag) and ESA's Cosmic Vision program.
Whichever proposal is chosen will have to fight for funding against other joint ESA/NASA proposals, including a next-generation X-ray telescope known as the International X-ray Observatory, and the Laser Interferometer Space Antenna which will study gravitational waves in space.
According to Peter Falkner, leader of planetary exploration studies at ESA, all of the missions and proposals will be narrowed down to two, and eventually one will be selected to "go forward to implementation."
Image Caption: Titan seen from the Cassini"“Huygens spacecraft. (NASA)
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