[X] My Assistant

[SpaceListener]

To land and take off between Mars and Moon are very different:

• Moon has 1/2 less gravity than in Mars.
• Moon has no atmosphere.

What will need more energy to land and take off per kilogram: Mars or Moon?

As the reference, the apollo lunar module 11 with weight of 14,696 kg landed on Moon. with the ascent module: 4,547 kg and the descent module: 10,149 kg. The LM descent propulsion system was more powerfull with 44.4 kN than the ascent propulsion system with 15.6 kN (ratio 3 to 1).

I tought that to land a big mass such as the Apollo 11 with over than 14,000 kilograms on Mars is actually impossible. It is hard for me to trade off between the Mars advantage of atmosphere to break the spacecraft and the Moon advantage of its half gravity to Mars.

[dvandorn]

The total energy required to land on Mars may be less than on the Moon, in relation to the mass you wish to land, because you can use the atmosphere to provide a good deal of your braking. However, you still have to deal with the Mach 5 problem, as is being discussed in another thread. The atmosphere just can't slow a large body to a velocity under Mach 5 before you have to start using rocket braking, and by that time you're so close to the ground you don't have enough time for rockets to slow you down to a zero landing velocity.

You need to start rocket braking earlier in the trajectory, going faster than Mach 5, and you need to apply that braking *into* the aerodynamic pressure pushing at you faster than Mach 5. That's the real challenge. The total energy required to achieve the landing is far less of an issue than figuring out how to apply that energy into a hypersonic slipstream.

-the other Doug