So, Mars is a stubborn planet that refuses to be terraformed. No matter how much air you import in order to create a atmosphere around it, it will be blown away in a short time. And there is one simple reason for this-Mars has no magnetic field.
This is the reason why Mars's atmosphere is so thin, that it makes Mt. Everest feel like Venus, why it receives Chernobyl-level radiation, and water simply boils away, due to the thin atmosphere. So, there are multiple solutions to this, but the most common one is to install satellite that installs a artificial magnetic field in Langrangian Point. But there are multiple obstacles in this technique.
Supposing that the satellite was impacted by a small projectile (forget asteroids) which could be a micrometeor, a meteor or even space debris, it would careen out of the Langrangian Point, and our artificial magnetic field goes brrrr....
I cannot see how a small satellite can generate a large magnetic field. Strength does not matter, you need a really large magnetic field to shield it from solar winds, about thousands of miles wide.
The satellite would have to deal with ion accumulation on its poles, in other words, the formation of artificial auroras on it, which would produce electric disturbances which would make our magnetic field malfunction.
So, there is a alternate solution, and that is-
a dwarf planet Ceres orbit Mars
The idea here is simple. Ceres is nudged from the Asteroid Belt, and is forced into the orbit of Mars.
The trick here is to get Ceres into a highly eccentrical orbit around Mars. This configuration causes a lot of tidal heating to occur on Mars, and the core heats up, and forms an magnetic field. Then later, large quantities of oxygen, water and nitrogen are imported from the Outer Solar System, and are made to create an substantial atmosphere around Mars.
What are the drawbacks of this technique?