Does it really make any huge difference in the amount of lunar dust disturbed or raised during a Moon landing while using a single-engine compared to using multiple engines?
I do not think there must be any difference because the amount of force required for a soft landing for the same active mass (mass of spacecraft+mass of fuel left in the tanks) of the spacecraft, is fixed, and it doesn't matter if we use a single-engine to provide a force of F newtons or four engines each providing F/4 newtons.
In a press conference, Dr.K.Sivan, Chairman of Indian Space Research Organisation (ISRO), told that initially, the Vikram lunar lander had only four engines for the final descent, but in testing they found the four engines cause the dust to raise a lot, due to which they added one more engine at the centre which will be used alone for soft landing, to minimize the dust disturbed. Lunar dust was considered as a major problem as it might cover the solar panels and sensitive instruments. One of the examples (supporting this), I can think of is the Apollo Lunar Lander which used only one engine for the touchdown.
I can't understand, how does the amount of dust raised depend upon the number of engines used for a touchdown? In the near future, I think the SpaceX's Starship might be using three of its vacuum optimized Raptor engines for the moon landing, how will they prevent dust from rising and covering habitats, solar panels, etc., with lunar regolith?
It would be helpful if you could explain how the number of engines influences the disturbance caused to lunar dust and possible ways to use multiple engines and minimize its effect.