[Steely Tom]

One of the main challenges NASA engineers face is the very low density of the Martian atmosphere. To be able to lift off in such a thin atmosphere, the blades of the Mars Helicopter have to spin much faster than here on Earth

Or be larger in blade area.

[WMarshal]

What we really need to do is be able to look deep into the crust of Mars to look for water which is impossible tiny drones. The next best thing would be a deep impact nuclear warhead.

[JimRed]

Or be larger in blade area.

Which could be a similar power drain, moving the larger blade surfaces? Six of one, half dozen of the other.