Scientists are drafting a plan to further explore Saturnian moon Titan, involving an orbiting spacecraft, surface probe and hot-air balloon designed to float gracefully through the body's hazy hydrocarbon atmosphere, Space.com reports.
However, while Cassini's radar and infrared instruments have offered tantalising glimpses of Titan, much remains to be explored.
Hence the proposed three-pronged attack by the Titan and Saturn System Mission (TSSM). Athena Coustenis, an astrophysicist and planetologist with the Paris Observatory who's involved in drafting the plan, said: "We need a Titan-dedicated orbiter because after four years of Cassini, we still haven't mapped more than 25 per cent of Titan's surface. When you see the diversity the moon has, you realize it needs full-coverage mapping. And we can have a polar orbiter, whereas Cassini only passes by Titan on the ecliptic."
Second up comes the surface probe - possibly a helicopter-style mobile unit fitted with floats to prevent it sinking beneath Titan's hydrocarbon waves. Coustenis explained: "Huygens was designed as a descent module, and there were no instruments designed to do surface science after landing. If you ask me what the dunes are made of, I don't know. The only way to find out what the surface is made of is to go touch it, sample it, and have a laboratory there that will analyze all the samples."
The ballooning jaunt, meanwhile, offers the prospect of a really good sniff of Titan's atmosphere - mainly made up of nitrogen and of particular interest to scientists because it may be similar to that on Earth billions of years ago, before oxygen generation kicked in.
The TSSM might also offer further insights into fellow Saturnian moon Enceledus, earlier this year subjected to an "in-your-face" flypast by Cassini which revealed a "surprising organic brew" erupting from its south polar region comprising "volatile gases, water vapour, carbon dioxide and carbon monoxide, as well as organic materials".
The TSSM, meanwhile, is up for evaluation by ESA and NASA who will in 2009 choose between the Titan ballooning trip and a mission to Jupiter and its moon Europa for a slated 2020 outer planets mission.
The TSSM may be technically innovative and therefore risky, but Coustenis insisted: "Why would we want to have a new mission unless we were going to do something original with it? This mission is challenging, but it's do-able. Even if it is a crazy idea, we shouldn't keep sending the same kinds of missions out there." ®