In 1996-1997, I became extremely enthusiastic about the space exploration prospects for aerobot technology. There seem to be at least 10 celestial bodies suitable for aerobot deployments: Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Enceladus, Europa, & Titan. I even published my master's thesis on the subject.
At the time, Kerry Nock was leading a group of scientists at JPL who were studying the subject with institutional funding. They did several experiments and published some of their results:
But in the nearly two decades since that time, there have been no aerobot missions (that I know of) and I've read very little about even proposed aerobot missions. Of those few I have encountered, they seem to get a little funding for study and then get abandoned in favor of more difficult missions.
I think an airborne aerobot on Titan must be one of the single most promising (in terms of discovering exobiology) and technologically feasible missions imaginable for the near future.
Why has this idea apparently been abandoned?
Are there scientific or engineering problems that make it impractical or too expensive? I have been unable to find any such issues myself. Or is it a political thing?
If DEPTHX (which strikes me as a kind of aerobot floating in water instead of air) got funded by NASA with the goal of developing technology that can explore the oceans of Jupiter's moon Europa (which first requires getting through miles of ice; no mean task), then why have there been no (or few) NASA or ESA funded projects for aerobots in less challenging environments like Titan or the upper atmosphere of Venus?