SriKumar wrote:
The advantage seems to be that they do not have to uncover/remove the airbag (could be a tricky procedure), but at the same time it seems a bit risky to rely entirely on the rockets to keep the rover fully balanced and horizontal and on a very slow descent. They must have tested the system thouroughly.
SriKumar, the complexties involved are enourmous sure. However retro rocket based landings have been done many times earlier too. In fact that was the more preferred method in during the space race of 50s-70s. So, with more modern systems in place we should be able to do it again. Of course the challenge is still there and its a complicated maneuver, hence chances of failure are part of the mission.
On a second note, the sky crane is a new thing and I think it is a bit easier for the rover to land horizontally, because gravity would keep the hanging rover upright even though the rocket based crane might be tilted a bit. As long as the rover is secured around its center of gravity, things are fine and that's something that would be done during the packing here on earth.
I guess because this rover is much larger, they have not gone with the air-bag thing. The added weight means that, that much larger and powerful airbags are required. Hence the need to carry that much amount of material to fill the airbags. Also airbag bounce would mean that there is less precise control over where the rover eventually comes to rest. Also when it comes to rest, what more maneuvering is required to bring it to the right position, because the airbag might result in the rover coming to rest upside down, so mechanism required for correcting it. With a small rover I guess the weight penalty for all this was much less, compared to the much bigger size of the current rover.
