An article, “The New Mars landing approach: How we’ll land large payloads on the Red Planet” by Nancy Atkinson (Phy.org.), was interesting to me because I have addressed the same issue in my upcoming book Outbound: Becoming Meta Mars. The difficulty arises because of several factors. We have done this on the Moon but there we only had to overcome 1/6th of Earth’s gravity. Effectively Mars is also airless having a more than 100 times thinner atmosphere than Earth, so aerobraking while it may assist, is not the answer. (Aerobraking is a technique that uses a planet’s atmosphere to slow down a spacecraft by creating drag.) SpaceX is working on retro rocket firing to slow re-entry speeds.

To land human landing-sized payloads (large cargo) on Mars the retro rockets would need to slow from an arrival speed that’s likely to be 12,000 mph (19,400 kps). The output from such an engine when hitting the atmosphere would create a shockwave that could disrupt the landing. Additionally, the back blast from the engines could damage the rocket.

In Outbound, heavy payloads are brought from orbit to the Martian surface via a space elevator. The descent would be controlled by regenerative braking. So instead of requiring huge amounts of energy, moving massive payloads to the surface would actually generate electricity.