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Aerial Drone To Hunt For Life On Mars
astroengine writes "What if the Martian terrain is too rugged for a rover to traverse? How do we study surface features that are too small for an orbiter to resolve? If selected by NASA, the Aerial Regional-Scale Environment Surveyor (ARES) could soar high above the Martian landscape, getting a unique birds-eye view of the Red Planet. Its primary mission is to sniff out potential microbial-life-generating gases like methane, but it would also be an ideal reconnaissance vehicle to find future landing sites for a manned expedition. Prototypes of the rocket-powered drone have been successfully flown here on Earth, so will we see ARES on Mars any time soon?"
What the GP is getting as is that the theoretically most efficient aerostat you can build is one with a rigid shell and an evacuated interior. It's not really a balloon, per se, hence the confusion.
Any actual balloon full of gas will always have less density differential than this, and thus generate less lift.
In practice, the mass of extra material required to build a rigid shell generally outweighs any extra lift you could get over a hydrogen or helium balloon. Hence, you don't see evacuated aerostats outside science fiction (e.g. Diamond Age by Neal Stephenson).
Be careful. People in masks cannot be trusted.