Moho Apollo Style?

[esinohio]

A friend and I were chatting the other day about one of the challenge threads, the Duna Apollo style. Its an older thread here . After all kinds of theory crafting for that thread the subject of even harder Apollo style missions came up. So the question is how far has someone pushed that design within the realm of KSP?

Would it be possible to do a mission to Moho using an Apollo style setup that used only chemical rockets? Three Kerbals leave Kerbin, two man staged lander, rover, etc. Specifically we were discussing a mission using those challenge rules linked above and assuming we want maximum points so that leaves out LV-Ns.

Edited April 11, 2014 by esinohio

[Jimbimbibble]

I think that would be impossible. You need somewhere around 20k dV to do a Moho landing/return and the only way I know to do that is the LV-N with lots of drop tanks on top of an asparagus lifter.

[Taki117]

I think that would be impossible. You need somewhere around 20k dV to do a Moho landing/return and the only way I know to do that is the LV-N with lots of drop tanks on top of an asparagus lifter.

A Moho mission can be done with far less than that. It is possible to do a round trip (Not including landing) with about 7km/s dV. The trick is to leave Kerbin orbit when Kerbin is at Moho Apoaps (or periaps) and include the plane change in the transfer burn.

[cantab]

Going by the delta-V map:

4550 m/s to reach LKO plus 1680 for the ejection burn, giving 6230. That's quite high, but should be within what a three-stage launcher can do (remember the Saturn V used the third stage for trans-lunar ejection.) The gotcha is that that's in an optimal launch window, but then waiting for said window isn't

The CSM then needs 5130 m/s to circularise at Moho, and later depart Moho back for Kerbin. 2200 of that needs to be done with the LM as payload. That is again quite high, but I believe doable, for a single stage; the limit with a 390 Isp engine and traditional tanks is 8397 m/s. Perhaps not in the spirit of the challenge but still perfectly viable and I feel reasonable would be a two-stage CSM.

The LM needs 2800 m/s. Entirely reasonable - Tylo needs much more.

Make no mistake, this is going to need a big rocket. Not Whackjob big, but still big.

You could reduce the delta-V requirements with an Eve gravity assist, at the cost of a longer transfer and probably waiting ages for the launch window. (You could reduce them more with repeated gravity assists, but then the time gets unbelievable for a manned mission.)

[maccollo]

The delta V map isn't quite accurate for Moho. It can either be much less or much more.

The ideal scenario will look something like this

First, 4500 m/s to escape Kerbin.

For an ideal encounter with Moho will need around 2400 m/s m/s from a single Kerbin escape burn.

Arriving at Moho you will then need about 1900 m/s.

1550 to get captured, 350 to lower that into a circular low Moho orbit.

The orbital velocity in low Moho orbit is around 820 m/s.

Should be able to land with 1100 if you know what you're doing.

Another 1100 for take off. The take off should take less.

Getting back to Kerbin will take another 1900 m/s.

So this adds up to:

12900 m/s, let's say 13 km/s. About what it takes to get to TLI in real life

[cantab]

I think you should start a Challenge of this, if there isn't one already. I'll definitely give it a shot.

[bsalis]

I think this is very doable. Especially if you leave Kerbin at the right time. You can get to Moho and back without making a plane change in transit, by leaving at the ascending or descending node. The new SLS parts and stronger joins make building a truly large rocket a piece of cake.

I think you should start a Challenge of this, if there isn't one already. I'll definitely give it a shot.

Agree - I might do the same. The cool thing about doing this for Moho is that the Apollo Moon mission profile will actually help. Where doing it for the Mun doesn't help, if at all, with all the extra parts (hence mass) for all the stages.

[esinohio]

Yikes!!! While I would LOVE to start a challenge... <cough> I'm not sure I can get my own submission up for the traditional "You posted the challenge so where is your submission". I'm giving it some attention here for sure. Pulling this off "on the cheap" has exposed some glaring holes in my piloting skills so I'm busy experimenting with resources linked all over on the finer points of gravity assists, etc. This will be done!!!! If for no other reason than just to pour salt in my friends wounds as he just didn't think this was possible. hehe. What are friends for ??

[Epthelyn]

Yikes!!! While I would LOVE to start a challenge... <cough> I'm not sure I can get my own submission up for the traditional "You posted the challenge so where is your submission".

The reason that guideline exists is so that people don't post really hard challenges without first checking whether or not they are actually possible. Since this mission is (on paper, and so theoretically in-game) possible you don't really need to prove anything; it's just a slightly more complicated craft than the relatively small vehicle you can do a Munar Apollo mission with.

As it is, it would be an interesting challenge.