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.

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    $\begingroup$ I have a hunch that it's more complex than "raising less" vs "raising more" dust. The direction and size of the scattered particles is also important. A ring of engines might leave a hole for particles shoot up the middle, whereas a single engine might push them away from the spacecraft as it lands. $\endgroup$
    – uhoh
    Oct 24, 2019 at 8:41
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    $\begingroup$ While the force might be the same, pressure might differ, i.e. spreading the same force on four engines (and so probably on a bigger area on the surface) might rise more dust towards the lander than one engine focused on a single area (see also previous comment by uhoh). $\endgroup$
    – BlueCoder
    Oct 24, 2019 at 8:46
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    $\begingroup$ @Fred, I don't personally think the number of engines will be a great concern. Falcon Heavy has 27 merlins, upcoming starship booster will have 37 raptors and so one. $\endgroup$
    – Vishnu
    Oct 24, 2019 at 11:42
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    $\begingroup$ @Fred I was eagerly waiting for the "more engines = more chances for failure" comment. Wonder why civil jet transports are all multi-engine, then. $\endgroup$ Oct 24, 2019 at 12:12
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    $\begingroup$ This website doesn't answer the question, but it contains a lot of references about it for someone interested in looking through them. Hopefully more information can be found in those: sciences.ucf.edu/class/landing-team/… $\endgroup$ Oct 24, 2019 at 19:04

1 Answer 1


Concern was not that the lunar dust will rise and cover the solar panels or instruments. The concern was as pointed out in the comments is that the dust particles rising up and hitting the lower bay of the lander and damaging or punching a hole.

The simulation was done to study plume interaction with soil, the four plume cones when they interact with ground the dynamics of exhaust gas is such that it will make particles launch directly up near the centre of the lander

Sole purpose of the central engine was to avoid this

In the end phase lander was supposed to use its thrusters along with central engine from 10 meters to touch down.


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