Mission Planning (Intermediate)

[GateCrasherVI]

Hey all! I imagine this has been covered before. And I've also read my fair share of relative forum posts, but I was kinda hoping to get some input and perhaps write up a specific run-down of events and the corresponding calculations. So, lemme get to the point.

How does one plan their lander / rover missions?

More specifically, I'm wanting to know how to most efficiently calculate the minimum TWR and DeltaV necessary so that the most efficient process is the starting point. We're all familiar with the whole "MOAR THRUST!!" approach to getting things done, or simple trial and error and rough estimation. Lots of fun to be had there.

Some of what I want to include in this "Guide to Mission Requirements" are things like...

• Start backwards with the result you want, for example, "a vehicle landed safely on the surface of a planet or moon", instead of just building the whole thing, from bottom to top all at once in a single go. (Trial and error, might is right. )
  
• Calculate the TWR & DeltaV necessary to get that vehicle home safely.
  
• Total the mass of both lander and return-flight stage and use that for the basis of initial launch vehicle minimum requirement.
  
• If using LOR ("lunar orbit rendezvous" like apollo was famous for having utilized courtesy of support from John Houbolt ) then calculate "time spent in orbital darkness" for after desired insertion / circularization. A nifty calculation that uses a great many of the basic equations necessary for this kind of rudimentary space flight planning. Through this you can make a considerably accurate estimate of battery life and solar recharging rate requirements. Especially handy for maintaining life-support and kethane scanners operational.
  
• With lander, and return vehicle mass now calculate the minimum required TWR and DeltaV for atmospheric escape, circularization, and hohmann transfer and stage the launch vehicle accordingly.
  

Maybe this is going a little too far with things for some people. I just think it'd be cool to have as simple a break-down as possible for say, Minmus and or the Mun, for KSP'ers like my son. I'm just kinda curious if I'm missing anything, or if anyone has a point in the right direction to this already done to some extent.

[Pecan]

The best example I have made is in the design of "Long Tom", in chapter 5 of the tutorial in my signature. But then the whole 100-odd pages is about how to plan and design for missions.

Specifically it talks about what has to be recovered at Kerbin, what it takes to get that back from Mun/Minmus, what's needed to land it, what to get it there and, as a separate launch-vehicle, what it takes to get that into orbit in the first place. Summary: I recommend planning in five stages, backwards through recovery, return, landing, transfer and launch. Building one rocket-stage per mission stage is a matter of preference; launch vehicles are usually large enough to require more than one stage while even a convenient transfer stage can also complete the landing, etc.

I wouldn't bother too much with orbital darkness - your vehicle is going to be spending a lot more time without sunlight while it's on the surface and, if it's a rover, will need a lot more while driving than while in space. You also need to plan for coming out of Mun's shadow, for instance, slap into a solar eclipse courtesy of Kerbin, which lasts until your next orbit. If you do specifically want to cover that point I wouldn't concentrate on Kerbin-system because even a z100 battery is sufficient for most light vehicles. Maybe talk about the comparative effectiveness of solar panels out at Eeloo orbital distance from the sun.

TWR is also only a significant issue when you're launching through an atmosphere - everywhere else it's >1 for launch and 'as low as your boredom threshold allows' for transfers.