Help me plan an extended mission to Jool's moons.

[Colonel_Panic]

Hi folks.

I recently completed the maiden voyage of my new explorer station, thus proving its capability for deployment and retrieval of extra-atmospheric munar landers. In a single trip, I deposited and retrieved 2 landers from both the mun and minmus, then returned to kerbin LKO with close to 3400 delta-v to spare. After refueling and re-outfitting the station with a newer, heavier lander, I want to make my next mission to visit Vall, Bop and Pol all in one go. I'm fairly confident I have the delta-v to get there if I play my cards right, although if I need to send a refueling tanker to make the return trip, that's acceptable too.

Here's my question: how should I go about it?

First and foremost, I want to visit all three moons, set down with landers, return those landers to the station, and move on to the next, using the minimum amount of delta-v... I guess it's kinda a traveling space salesman issue, however there's a few other mission objectives I'd like to meet: I also want to visit points of interest on Vall and Bop.

I would presume that the most efficient path probably involves aerobraking at Jool or Laythe into Vall's orbit, aiming to hit a polar inclination, then burn to capture and use my heavy lander to fine-tune the approach, land, return to the station, then try and find a transfer window that lets me escape the polar orbit as flat as possible into Vall's prograde to hit Bop, possibly via Tylo gravity assist, determine a minimum orbital inclination that will allow me to reach the point of interest, capture on it, wait for a window to land at the desired location, land, return, find a transfer window to Pol, eject as flat as possible and perform a Hohmann transfer, aim for a 0 inclination capture, send down the lander, return, and then just hope my pol ejection and kerbin transfer windows overlap....

So here's my questions...

1) Can I shave off any reasonable amount of delta v by using a munar assist on my kerbin ejection?

2) is it more efficient to reach vall via jool aerobraking, laythe aerobraking, or a combination of both? what is the second most efficient method in case the conditions to using the first turn out non-favorable?

3) how much delta-v will I need to land on vall from a low vall orbit, and return to orbit again? assume a single stage, fully re-usable lander.

4) how difficult will it be to escape a polar orbit on vall via vall prograde into the correct orbital plane to hit Bop? how much extra delta v should I assume this maneuver will require versus a flat transfer from an equatorial orbit?

5) what are the actual coordinates of the point of interest on vall, and what orbital inclination do they lie on? (please use spoiler tags for the coordinates. I can't get ISA mapsat to work on 0.20 or I would find out myself.)

6) Is a tylo gravity assist to reach bop from vall feasible? Is it recommended for correcting my inclination?

7) what are the coordinates of the kraken on bop, and what's the minimum orbital inclination I can hit to reach them? (again, please use spoiler tags)

8) should I try and eject from pol directly into my kerbin transfer window, or should I eject early and try to make the transfer from an outer orbit of jool?

9) how much delta v do you think this all might take? is it all a pipe dream? am I doing this all wrong and should I approach it differently? please post comments below.

For the record, my station has about 5300 delta v not including the weight of the heavy landers, in its current configuration. I estimate around 4800dv with the landers docked and fully loaded. I can improve it somewhat by leaving behind unneeded hitchhiker containers and/or replacing them with fuel tanks, but I want to make this mission with the minimum amount of modifications, so I'd rather send a fuel tanker to meet me at pol for the return trip, than retrofit the station before leaving. Just looking at transfer burn requirements I calculate I can do it in approximately 4160 delta v round trip, taking into account about a 15% wiggle room on maneuvering fuel, but NOT counting capture burns and major changes in inclination, so I really don't know how much more those things will set me back. I figure for bop and pol it will be minimal, but for Vall it could be a mission breaker.

Thanks in advance!

Edited May 26, 2013 by Colonel_Panic

[Cesrate]

Too many questions...

Sorry that I have less experience on Jool system, I'll answer Q1. It will indeed save some(but not big) ÃŽâ€v. Without assist you'll have to accelerate to escape velocity, while with assist you just need to accelerate to Munar transfer velocity, if you set your Munar periapsis close enough to the Mun.

[Cesrate]

For such a long trip, NTR+rejectable tanks will be a good choice.

[Colonel_Panic]

For such a long trip, NTR+rejectable tanks will be a good choice.

I really don't want to be dropping any tanks. The dry weight of the station is high enough that shedding empty tanks wouldn't save that much mass anyway, but mostly I just want it to be fully re-usable. The idea being I need only return to kerbin to refuel after a mission.

[Richy teh space man]

ISA Mapsat is working in 0.20 now, check the blog from the maker of it.

[Colonel_Panic]

ISA Mapsat is working in 0.20 now, check the blog from the maker of it.

link please? I'm not finding it, only old versions.

[Scub]

link please? I'm not finding it, only old versions.

I'm downloading it for the first time, thought I'd drop you the link as well.

http://forum.kerbalspaceprogram.com/blog.php/16471-Innsewerants

[Colonel_Panic]

Thanks.

I got it installed now, but it's not working. :/ GUI appears to be broken. tried uninstalling other mods to check for conflicts but no joy.

[Scub]

Same. Launched a test mission to Mun, got in orbit but could not get anything to work. You have to click the invisible spotwhere the UI is supposed to be in order to get the menu. (lower left) But even then it seems to be none functional.

[AustralianFries]

1) Yes, technically you can save some Delta V. But it may turn out to be more complicated/more expensive to set up a Munar encounter while escaping.

2) I'd go with full Jool aerobreak. Anywhere from 118k to 111k should work (although I'd quicksave before this). A bit deeper if you really wanna get in close. However since you want to visit more planets I'd go with a higher aerocapture.

3) I cant think up an exact number, let alone a fully accurate range of two numbers.

4) You will be saving a lot more delta v by an equilateral transfer than a 90 degree plane change and then transfer. (Although if this station/flight is as big as you are making it out to be you shouldn't have a problem doing either.) If you're landing on Vall to get to the henge I'd recommend plane changes while taking off and landing, while keeping your station/main ship in an equilateral orbit.

5) Spoiler tags are broken. If you don't want to know the whereabouts of the anomaly on Vall don't read this. As far as exact coordinates, I don't really know. However I know it's just north of the south pole on the base of some mountains. Lemme get a picture and I can make a pretty good estimate as to where it is. (Will edit once estimate is made.)

6) Kinda goes with the Mun ordeal. Yes, you could. But it would take a lot more time, planning, and delta v to do it. Plus, it could through off your inclination. I wouldn't recommend it.

7) Will look up in a second.

8) You'll pretty much be using the same amount of delta v so it doesn't really matter. If you're really tight on fuel I'd just go directly out from Pol, but if you want more precision and don't feel like being rushed then go with a Jool exit. But like I said it wont matter too much.

9) No clue. A lot.

[DMagic]

I did something similar to this a little while ago, but I dragged along a Tylo lander, too.

Are you planning on taking the station along to each moon, or releasing the landers at some other point and having them return later? It takes almost nothing to land and take off from Bop and Pol, but it takes a ton of delta-v to get in and out of orbit around each moon. It is possible to use Tylo for the inclination change though. I've done that before going from Bop to Pol and it worked really well, but I didn't plan in it, I just had lucky timing.

Vall takes a lot to land and take off from, I think around 1100 m/s.

You can see my post here for a lot more detail about how I did all of this.

http://forum.kerbalspaceprogram.com/showthread.php/29028-Manned-Jool-survey

[Colonel_Panic]

4) You will be saving a lot more delta v by an equilateral transfer than a 90 degree plane change and then transfer. (Although if this station/flight is as big as you are making it out to be you shouldn't have a problem doing either.) If you're landing on Vall to get to the henge I'd recommend plane changes while taking off and landing, while keeping your station/main ship in an equilateral orbit.

Doing a plane change in low orbit would be very fuel expensive, and my landers are minimal single-stage affairs designed only to reach the surface and return to orbit. I don't want to risk running out of fuel before I can make the rendezvous with the station again. I know I can hit a 90 degree inclination for almost zero fuel if I perform the inclination change far enough out near the edge of vall's SOI, but getting back on track when departing again is different, and I don't know how well a transfer to another planet will even work if I'm in a 90-degree inclined orbit. I suppose if I'm lucky and my orbit takes me through vall's prograde and antigrade vectors around jool during my departure window, but that's kind of a gamble, and I don't know how well the moons will play with lining up a departure window that works considering.

I did something similar to this a little while ago, but I dragged along a Tylo lander, too.

Are you planning on taking the station along to each moon, or releasing the landers at some other point and having them return later? It takes almost nothing to land and take off from Bop and Pol, but it takes a ton of delta-v to get in and out of orbit around each moon. It is possible to use Tylo for the inclination change though. I've done that before going from Bop to Pol and it worked really well, but I didn't plan in it, I just had lucky timing.

Vall takes a lot to land and take off from, I think around 1100 m/s.

You can see my post here for a lot more detail about how I did all of this.

http://forum.kerbalspaceprogram.com/showthread.php/29028-Manned-Jool-survey

Thanks. I'm planning to visit each moon with the station, and deploy 6the lander in low orbit, then scoop it back up again before moving on. This allows me to use small re-fuelable single-stage landers so I only have to bring 2 for the mission to have one spare.

[DMagic]

Thanks. I'm planning to visit each moon with the station, and deploy 6the lander in low orbit, then scoop it back up again before moving on. This allows me to use small re-fuelable single-stage landers so I only have to bring 2 for the mission to have one spare.

In that case you're going to need at least 4000-5000 m/s of delta-v just for getting into and out of orbit from the 3 moons.

[Colonel_Panic]

Is there a better way you'd suggest doing this so I can deploy and recover each lander in the process?

[Colonel_Panic]

So I'm actually now thinking of ditching this plan and starting a newer, even more ambitious project to create an omnilander capable of reaching, landing on and returning to kerbin from every body in the kerbol system (excepting Eve and Jool) using only orbitally-refittable parts, and assembling an orbital assembly platform capable of servicing it between missions and storing/refueling all the parts necessary for the refits.

[Gaiabladegold]

Waypoint fule canisters is the way I'd go. An ambitious mission, I barely managed a return trip from Duna after having to launch a rescue mission... but all 12 Kerbals made it back safe and sound. It will be interesting deciding on a lander suited to diverse situations like Tylo's kerbin-like gravity, and Moho's high heat frying high-output engines... Not to mention the transfer system as well. Moho and Jool would be the most challenging in those regards, moreso Moho, since Jool you can Aerobrake...

[CalculusWarrior]

Interesting mission plan, and very ambitious! I shall try to answer all your questions in order.

1. No, a Munar gravity assist will not save you much delta-v to be worth the trouble to wait for the planets to all line up (only about 100 m/s). However, if you can manage it I find that it looks really cool, flying by the Mun and then out to interplanetary space!
   
2. When entering the Jool system, aerobraking around the gas giant is a must, unless you have an excess of fuel and enjoy wasting it. Braking around Laythe however... While it is a good tactic for coming into land, I don't see how you could line up the vectors properly to get another moon encounter after you've aerobraked there. In my opinion, your best bet is to aerobrake only at Jool to get your apoapsis to where you desire.
   
3. According to my charts, Vall requres 1176 m/s to land or take off from (i.e. 2352 m/s total).
   
4. A fun little formula I have come across is that the delta-v requred to to a complete 90 degree plane change maneuver is actually the root of 2 multiplied by your current velocity. Therefore, the slower you are going (the higher the orbit), the less delta-v you requre to do the burn. If I had to do this, I would engineer extra delta-v into my lander so that it can make the plane change maneuver to reach the sourth pole, and keep the interplanetary craft in a very high equatorial orbit. (I'm assuming that the highest orbit that you can reasonably orbit at is 2 000 km, which translates to an orbital velocity of ~300 m/s, therefore your plane change delta-v is 425 m/s). Then, I would simply plane change in the lander (which will be easier than a massive interplanetary spacecraft), land, sightsee, and then take off, ascend to your desired orbital altitude, make the final plane change, and then rendezvous with your ship.
   
5. I've been beaten to the punch here...
   
6. Like the Mun, if everything lines up and you can get the orbits to work, sure, but don't waste too much time trying to get it to happen.
   
7. See number 5. :/
   
8. As long as Pol is in the correct location when you begin your transfer burn, it shouldn't make too much of a difference as long as you have enough fuel to get home!
   
9. You had better add a buttload of fuel onto your ship because the total delta-v needed will be:
   

4500 m/s to reach LKO, 950 extra to escape. 963 m/s to raise apoapsis to Jool orbit, and aerobraking is free (assuming you get the correct altitude).

TOTAL DELTA-V: 1913 m/s (this ignores delta-v for lifting off of Kerbin)

If you put your apoapsis onto Vall's orbit and time accelerate until you get an encounter with the moon, you can get a Vall encounter fairly easily and without expending a whole lot of delta-v. However, you will have to expend 790 m/s to achieve a circular orbit. Like I said, Vall landing and takeoff will take 2352 m/s total, along with 850 m/s for plane change maneuvers. Transferring to Bop will requre 315 m/s, along with some more to perform the plane change. I'd estimate about 500 m/s? Then decelerating into Bop orbit will require more fuel, which my charts read as 950 m/s.

TOTAL DELTA-V: 7670 m/s

Now we are on Bop. To land, we require 276 m/s, though let's round that up to 300 m/s for any plane change maneuvers needed. After landing on Bop, we want to get to Pol. This only requires around 60 m/s, but there is a bit of a plane change that you'll have to undergo as well, which we'll assume is 300 m/s. Finally, to decelerate, we require maybe another 900 m/s of delta-v? These figures are for transferring from low Jool orbit, and you will probably require less of a burn in reality, but it's helpful to have extra fuel for a mission.

TOTAL DELTA-V: 9530 m/s

Now, in Pol orbit, we need to land. This requires only a tiny 180 m/s, which is less than required for landing on Minmus! After you've done all you want to do on Pol (plant flags, look at the stars/Jool) and lifted off, it comes time for the glorious return to Kerbin! A Jool ejection burn back to Kerbin's SoI will require 3 km/s of delta-v. After that, though, feel free to coast into the Kerbin system, jettison your crew capsule, deploy parachutes, and splash/touchdown safely!

TOTAL DELTA-V: 12890 m/s

That is a lot of delta-v required. However, it is not the total change in velocity required for the main ship to undergo. A lot of that comes from having the landers perform landing maneuvers on the various moons. A revised counter would read:

TOTAL SPACECRAFT DELTA-V: 8728 m/s (round up to 9000 for safety)

VALL LANDER DELTA-V: 3202 m/s

BOP LANDER DELTA-V: 600 m/s

POL LANDER DELTA-V: 360 m/s

Looking at that data, I would suggest that you bring both a heavy-duty Vall lander as well as a lighter Bop and Pol lander. After Vall, ditch the heavy lander and carry a reduced weight to the other two moons.

All I can say now is good luck, and may you succeed in your mission!

[Colonel_Panic]

Waypoint fule canisters is the way I'd go. An ambitious mission, I barely managed a return trip from Duna after having to launch a rescue mission... but all 12 Kerbals made it back safe and sound. It will be interesting deciding on a lander suited to diverse situations like Tylo's kerbin-like gravity, and Moho's high heat frying high-output engines... Not to mention the transfer system as well. Moho and Jool would be the most challenging in those regards, moreso Moho, since Jool you can Aerobrake...

I did attempt a moho flyby earlier to deposit a refueling tanker in orbit... but I found it was impossible to reach given my non-ideal departure window against moho's inclination, even given my NINE THOUSAND delta-v of the tanker. I failed to complete the circularizing burn, so I have an empty tanker probe just floating around an eccentric orbit of moho now. It is without question the most difficult planetoid to reach in the kerbol system. I might have to find some special departure window when the orbital plane is easier to reach from kerbin.

[Colonel_Panic]

Interesting mission plan, and very ambitious! I shall try to answer all your questions in order.

1. No, a Munar gravity assist will not save you much delta-v to be worth the trouble to wait for the planets to all line up (only about 100 m/s). However, if you can manage it I find that it looks really cool, flying by the Mun and then out to interplanetary space!
   
2. When entering the Jool system, aerobraking around the gas giant is a must, unless you have an excess of fuel and enjoy wasting it. Braking around Laythe however... While it is a good tactic for coming into land, I don't see how you could line up the vectors properly to get another moon encounter after you've aerobraked there. In my opinion, your best bet is to aerobrake only at Jool to get your apoapsis to where you desire.
   
3. According to my charts, Vall requres 1176 m/s to land or take off from (i.e. 2352 m/s total).
   
4. A fun little formula I have come across is that the delta-v requred to to a complete 90 degree plane change maneuver is actually the root of 2 multiplied by your current velocity. Therefore, the slower you are going (the higher the orbit), the less delta-v you requre to do the burn. If I had to do this, I would engineer extra delta-v into my lander so that it can make the plane change maneuver to reach the sourth pole, and keep the interplanetary craft in a very high equatorial orbit. (I'm assuming that the highest orbit that you can reasonably orbit at is 2 000 km, which translates to an orbital velocity of ~300 m/s, therefore your plane change delta-v is 425 m/s). Then, I would simply plane change in the lander (which will be easier than a massive interplanetary spacecraft), land, sightsee, and then take off, ascend to your desired orbital altitude, make the final plane change, and then rendezvous with your ship.
   
5. I've been beaten to the punch here...
   
6. Like the Mun, if everything lines up and you can get the orbits to work, sure, but don't waste too much time trying to get it to happen.
   
7. See number 5. :/
   
8. As long as Pol is in the correct location when you begin your transfer burn, it shouldn't make too much of a difference as long as you have enough fuel to get home!
   
9. You had better add a buttload of fuel onto your ship because the total delta-v needed will be:
   

4500 m/s to reach LKO, 950 extra to escape. 963 m/s to raise apoapsis to Jool orbit, and aerobraking is free (assuming you get the correct altitude).

TOTAL DELTA-V: 1913 m/s (this ignores delta-v for lifting off of Kerbin)

If you put your apoapsis onto Vall's orbit and time accelerate until you get an encounter with the moon, you can get a Vall encounter fairly easily and without expending a whole lot of delta-v. However, you will have to expend 790 m/s to achieve a circular orbit. Like I said, Vall landing and takeoff will take 2352 m/s total, along with 850 m/s for plane change maneuvers. Transferring to Bop will requre 315 m/s, along with some more to perform the plane change. I'd estimate about 500 m/s? Then decelerating into Bop orbit will require more fuel, which my charts read as 950 m/s.

TOTAL DELTA-V: 7670 m/s

Now we are on Bop. To land, we require 276 m/s, though let's round that up to 300 m/s for any plane change maneuvers needed. After landing on Bop, we want to get to Pol. This only requires around 60 m/s, but there is a bit of a plane change that you'll have to undergo as well, which we'll assume is 300 m/s. Finally, to decelerate, we require maybe another 900 m/s of delta-v? These figures are for transferring from low Jool orbit, and you will probably require less of a burn in reality, but it's helpful to have extra fuel for a mission.

TOTAL DELTA-V: 9530 m/s

Now, in Pol orbit, we need to land. This requires only a tiny 180 m/s, which is less than required for landing on Minmus! After you've done all you want to do on Pol (plant flags, look at the stars/Jool) and lifted off, it comes time for the glorious return to Kerbin! A Jool ejection burn back to Kerbin's SoI will require 3 km/s of delta-v. After that, though, feel free to coast into the Kerbin system, jettison your crew capsule, deploy parachutes, and splash/touchdown safely!

TOTAL DELTA-V: 12890 m/s

That is a lot of delta-v required. However, it is not the total change in velocity required for the main ship to undergo. A lot of that comes from having the landers perform landing maneuvers on the various moons. A revised counter would read:

TOTAL SPACECRAFT DELTA-V: 8728 m/s (round up to 9000 for safety)

VALL LANDER DELTA-V: 3202 m/s

BOP LANDER DELTA-V: 600 m/s

POL LANDER DELTA-V: 360 m/s

Looking at that data, I would suggest that you bring both a heavy-duty Vall lander as well as a lighter Bop and Pol lander. After Vall, ditch the heavy lander and carry a reduced weight to the other two moons.

All I can say now is good luck, and may you succeed in your mission!

Good Lord, excellent post, thanks!

It does look like I'll need to refit my station for longer range, possibly swapping out the outer crew modules for more fuel tanks. I know 9000 isn't unrealistic to attain if your wet:dry weight ratio is high enough, but it's definitely nearing the point of diminishing returns... this will be very hard indeed to carry out successfully under my current plan.

EDIT: I had planned to bring one heavy lander and one light lander, but truth be told my estimation for a vall landing was closer to 5500 than 3000, so I may be able to slim it down more.. leaving the lander behind, or perhaps... and here's a slick idea... making a heavy lander stage for the light lander, and staging it on vall ascent to return only the light lander to the ship, giving me 2 light landers top carry on to bop and pol, could work very nicely.

EDIT 2: Wouldn't trying to capture on a higher orbit require a lot more delta-v than a low orbit for vall? I know I can for example dispatch my lander as soon as entering vall's SOI to do the plane change maneuver and save fuel there (can do the same with the station), though after doing that I'd have the lander and station on different planes, which could take a lot to get back from. I guess I don't know how the delta-v cost of a low vs high holding orbit works out, though I guess the d-v I expend in a high capture orbit, I might save on escape again to the next moon? It's something to consider, just requires thinking a lot about the lander's capability and how to balance it all with the station's.

Edited May 28, 2013 by Colonel_Panic

[Gaiabladegold]

Yeah, Moho transits usually go the same way for me, I think... It'll definately be one of the challenges on an interplanetary tour of the kerbin system, and a successful return mission from that baked dirtball's sizzling surface alone will be an accomplishment in its own right... And will take some careful planning of fuel reserves to get there, and then back again...

But I was just recalling one way I managed to get there with surprising success a while back was by slingshotting off Eve, actually... Won't lie, it was a damn miracle of sorts, because what started as an attempted returning trip to Eve itself, turned into a screwed up time warp on my part that left me swinging past my mark into an orbit with a periapsis just shy of Moho's orbit... But the ship had plenty of fuel to spare, and was mildly lightweight under a dozen or so tanks of fuel for the Eve ascent attempt to begin with, so it didn't take a huge burn to do the descent for Moho after a few transfers and dumping of empty canisters into the transfer engines, and I managed to avoid blowing up during the final burn... XD

Since you're not planning on landing at Eve anyway, maybe this could be feasible? It'll be tricky to pull off... but perhaps save you a few thousand delta-Vs if it can be done... ^^;

[DMagic]

EDIT: I had planned to bring one heavy lander and one light lander, but truth be told my estimation for a vall landing was closer to 5500 than 3000, so I may be able to slim it down more.. leaving the lander behind, or perhaps... and here's a slick idea... making a heavy lander stage for the light lander, and staging it on vall ascent to return only the light lander to the ship, giving me 2 light landers top carry on to bop and pol, could work very nicely.

That's a good idea, put some radial tanks for the Vall landing and take off, then just leave a really small lander in the center. Bop and Pol require almost nothing just to land and take off from, I think a single LV-909, the little lander engine, and a either a 90 or 180 unit tank would be enough for part of the Vall ascent and a Bop/Pol landing and return.

You will have to be careful balancing your original carrier though, the heavy lander will make it difficult to control until you can get rid of that weight. I had this problem on my Jool moon mission. My solution was to activate and deactivate a nuclear engine on the side of the heavy Tylo lander to keep me pointed straight. It was a lot of trouble, but it worked pretty well.

[Temstar]

It's better to shift a lot of those delta-V into lander stages instead of keeping it all in your mothership. If I were to do this mission this is what I would do:

1. Mothership with three landers docked arrive in the Jool system, aerocapture around Jool to Laythe orbit altitude, aerocapture around Laythe to brake into Medium Laythe Orbit

2. Undock the three landers, each lander perform a moon-to-moon transfer to their target. Land and then get back to low orbit of each moon.

3. All landers perform another moon-to-moon transfer back to Laythe to dock back with the mothership, taking advantage of aerocapture at Laythe

4. Mothership depart Laythe during a Kerbin transfer window to come back. You'll have to make sure you hit Laythe ejection angle, Jool ejection angle and Kerbin phase angle in one burn.

For the landers, you may want to consider a lander/tug model where before their deorbit burn, each lander leaves an orbital stage in orbit with the NTR and fuel needed to get back to Laythe and land only the gear required to land and take off back to orbit to meet the tug stage. If done this way you can actually do both Bop and Pol in one go with a single lander.

In fact if you go for the lander/tug model you can actually visit all three of your target moon AS WELL as Laythe with a single lander:

1. Mothership arrive at Jool for aerocapture, arrive at Laythe for aerocapture and insert into LLO

2. Laythe lander undock and makes a parachute assisted landing on Laythe

3. Mothership undocks two simple small fuel tankers, the tankers make a moon-to-moon transfer to Vall and Bop

4. Laythe lander takes off to redock with the mothership, the top stage of the Laythe lander is now your airless moon lander

5. lander refuel from Mothership and is docked with a tug stage. Tug stage fire to send the lander to Vall

6. at LVO, lander undock from tug and make a Vall powered landing, then return to LVO to dock with the tug stage

7. Tug stage and lander dock with tanker 1 to refuel

8. Lander and tug make a moon-to-moon transfer to Bop

9. Lander undocks, makes a landing, get back to orbit and dock with the tug stage. The two then dock with tanker 2 to refuel

10. Lander and tug make a moon-to-moon transfer to Pol

11. Lander undocks, makes a landing, get back to orbit and dock with the tug stage.

12. Tug stage fire to send the lander back to Laythe. Tug is allowed to crash into Laythe while lander aerocapture into LLO to dock back with the mothership.

To give an example of this kind of lander + tug stage, here is my Gilly lander which I used as part of my manned Eve landing mission:

Lander and Tug undocking from mothership

Lander + Tug assembled in LEO

Lander undocking in Low Gilly Orbit

Eve landing

Re-docking with tug stage

Re-assembling with the mothership.

For Bop and Pol your lander could be as small as my Gilly lander here. For Vall you will need something more beefy but you might also want to consider the option of building the Vall landing stage as another separate craft to be sent to Vall ahead of the lander. The lander then just docks onto of the Vall landing stage and ride on it for that leg of the mission.

I once did a manned landing mission to all four Jool moons (Pol wasn't available in 0.17 when I did it) using a fairly similar architecture as above. The Laythe lander was reused for Vall by refuelling with the mothership waiting in Laythe orbit. Unfortunately that mission report got eaten by the forum purge.

Here is a shot of the mothership and three landers I used for that mission:

Edited May 28, 2013 by Temstar

[Colonel_Panic]

Yeah, Moho transits usually go the same way for me, I think... It'll definately be one of the challenges on an interplanetary tour of the kerbin system, and a successful return mission from that baked dirtball's sizzling surface alone will be an accomplishment in its own right... And will take some careful planning of fuel reserves to get there, and then back again...

But I was just recalling one way I managed to get there with surprising success a while back was by slingshotting off Eve, actually... Won't lie, it was a damn miracle of sorts, because what started as an attempted returning trip to Eve itself, turned into a screwed up time warp on my part that left me swinging past my mark into an orbit with a periapsis just shy of Moho's orbit... But the ship had plenty of fuel to spare, and was mildly lightweight under a dozen or so tanks of fuel for the Eve ascent attempt to begin with, so it didn't take a huge burn to do the descent for Moho after a few transfers and dumping of empty canisters into the transfer engines, and I managed to avoid blowing up during the final burn... XD

Since you're not planning on landing at Eve anyway, maybe this could be feasible? It'll be tricky to pull off... but perhaps save you a few thousand delta-Vs if it can be done... ^^;

Well, in theory... all you really need to do is hit a phase window to Eve that puts your eve flyby near the ascending or descending node of moho's orbit... then hit an inclination entering Eve's SOI that will spit you back out on moho's plane, and then wait for an opportunity to perform a hohmann transfer to moho from kerbol orbit. It would undeniably be hard to do, but it's definitely doable... your kerbals might put on a few years in the cooler while they're waiting in the process, too.

EDIT: If I ever do a return trip to moho I probably will do this... and if I'm successful I'll post a tutorial on how to pull it off.

[Colonel_Panic]

You will have to be careful balancing your original carrier though, the heavy lander will make it difficult to control until you can get rid of that weight. I had this problem on my Jool moon mission. My solution was to activate and deactivate a nuclear engine on the side of the heavy Tylo lander to keep me pointed straight. It was a lot of trouble, but it worked pretty well.

It sho8uldnt be a big problem. I can design the lander to have a weight difference from the smaller lander roughly equivalent to one or two crew modules, and then just leave the ones from that side of the station behind at the drydock. I might for the mission end up swapping some of them for furl tanks, too, and can do a dry vs wet weight calculation before sending them up for retrofit.

It's better to shift a lot of those delta-V into lander stages instead of keeping it all in your mothership. If I were to do this mission this is what I would do:

1. Mothership with three landers docked arrive in the Jool system, aerocapture around Jool to Laythe orbit altitude, aerocapture around Laythe to brake into Medium Laythe Orbit

2. Undock the three landers, each lander perform a moon-to-moon transfer to their target. Land and then get back to low orbit of each moon.

3. All landers perform another moon-to-moon transfer back to Laythe to dock back with the mothership, taking advantage of aerocapture at Laythe

4. Mothership depart Laythe during a Kerbin transfer window to come back. You'll have to make sure you hit Laythe ejection angle, Jool ejection angle and Kerbin phase angle in one burn.

For the landers, you may want to consider a lander/tug model where before their deorbit burn, each lander leaves an orbital stage in orbit with the NTR and fuel needed to get back to Laythe and land only the gear required to land and take off back to orbit to meet the tug stage. If done this way you can actually do both Bop and Pol in one go with a single lander.

In fact if you go for the lander/tug model you can actually visit all three of your target moon AS WELL as Laythe with a single lander:

1. Mothership arrive at Jool for aerocapture, arrive at Laythe for aerocapture and insert into LLO

2. Laythe lander undock and makes a parachute assisted landing on Laythe

3. Mothership undocks two simple small fuel tankers, the tankers make a moon-to-moon transfer to Vall and Bop

4. Laythe lander takes off to redock with the mothership, the top stage of the Laythe lander is now your airless moon lander

5. lander refuel from Mothership and is docked with a tug stage. Tug stage fire to send the lander to Vall

6. at LVO, lander undock from tug and make a Vall powered landing, then return to LVO to dock with the tug stage

7. Tug stage and lander dock with tanker 1 to refuel

8. Lander and tug make a moon-to-moon transfer to Bop

9. Lander undocks, makes a landing, get back to orbit and dock with the tug stage. The two then dock with tanker 2 to refuel

10. Lander and tug make a moon-to-moon transfer to Pol

11. Lander undocks, makes a landing, get back to orbit and dock with the tug stage.

12. Tug stage fire to send the lander back to Laythe. Tug is allowed to crash into Laythe while lander aerocapture into LLO to dock back with the mothership.

To give an example of this kind of lander + tug stage, here is my Gilly lander which I used as part of my manned Eve landing mission:

Re-assembling with the mothership.

For Bop and Pol your lander could be as small as my Gilly lander here. For Vall you will need something more beefy but you might also want to consider the option of building the Vall landing stage as another separate craft to be sent to Vall ahead of the lander. The lander then just docks onto of the Vall landing stage and ride on it for that leg of the mission.

I once did a manned landing mission to all four Jool moons (Pol wasn't available in 0.17 when I did it) using a fairly similar architecture as above. The Laythe lander was reused for Vall by refuelling with the mothership waiting in Laythe orbit. Unfortunately that mission report got eaten by the forum purge.

Here is a shot of the mothership and three landers I used for that mission:

Yeah, I know it's more efficient (aka, 'better') to offload the intensive maneuvering on the smaller craft. I wanted to do it this way to prove it could be done, and to test the ultimate capabilities of my mothership. I am in effect using the mothership -as- a tug for the landers on this mission, it's just a very large tug with a lot more dry weight. Part of the scope of the mission is going to be just having that station full of science kerbals in orbit over each moon during the landings. Your idea of parking at laythe though is a good one with a lot of merit for the aerobraking capability. I think ultimately I may need to send a full-fledged space dock to laythe orbit there to further research missions in the area.