On 4/19/2018 6:26 PM, Fred J. McCall wrote:
JF Mezei wrote on Thu, 19 Apr 2018
18:07:43 -0400:

On 2018-04-19 16:20, David Spain wrote:

Yes I agree. I suspect they are using it mainly for learning curve
rather than practical economics, with BFR looming.

Could balloons be used for landing cargo on Mars? (yeah, they would need
to be huge ballons due to low atmosphere pressure).


Only part way. You could use a balloon (or ballute) to increase cross
sectional area to increase drag for aerobraking, but you're not going
to actually get enough lift to land anything that way. There was a
'balloon/bouncy house' solution where the balloon(s) expanded around
the payload which then aerobraked and was simply allowed to strike the
surface. This only works for light payloads and I don't know if they
ever tried it.



Fred this was tried at least once I can remember. The first Mars rovers
(Spirit & Opportunity) were light enough that inflated balloons where
used to bounce land them on the surface of Mars after parachute.

The follow-on rover Curiosity was too heavy for that approach and used
the sky-crane retro-rocket approach after parachute.

Dave