Grand Tour Delta-V!

[AtomicTech]

How many m/s does it take to go fly-by every planet and moon?

[Starman4308]

If you're willing to use lots of gravity assists: less than 1500 m/s from LKO, enough to set up an Eve flyby, then small correction burns. Were I to do it, I'd probably pack 3 km/s or so, on account of being OK but not amazing at setting up gravity assists.

If you're wanting to land on every body, that's going to take some doing, and would be most practical via use of ISRU. For that, in addition to gravity assists, I'd probably budget at least 4 km/s on the main transfer vehicle, and probably put Eve, Laythe, and Tylo landers in orbit of those bodies ahead of time.

Well, I'd actually just skip Eve, but the principle stands: a main transfer stage, an ISRU tanker/lander attached to it, and pre-place specialized landers near every body for which the general-purpose tanker won't really work. I'm sure people have done single-launch missions to the surface of every body including Eve, but I'm willing to do multiple launches.

[camacju]

I think this would be the most efficient way to flyby every body although I could be wrong:

Start in Kerbin orbit
Mun transfer
Use Mun and Kerbin assists to get to Eve
Time your Eve encounter so you fly by Gilly also. If that's not reasonable then just skim by Eve while touching Gilly's orbit and then get another encounter later
Use Eve assists to get to Moho. Again just skim by to not alter your trajectory too much so you still intersect Eve's orbit
Use Eve and Kerbin assists to get to Jool
In Jool's sphere of influence, fly by Laythe and set up a good Eeloo encounter
Fly by Eeloo and return to Jool
Use Tylo and Vall to capture and get encounters with Bop and Pol, then escape Jool on a trajectory to Dres
Get a weak Dres encounter so you don't mess up your Jool intersecting orbit, then encounter Jool again
In Jool's sphere of influence get a Laythe or Tylo assist to lower your transfer orbit down to Duna, aerobrake there and fly by Ike
Then you're home free - get a Kerbin encounter with Ike assists, Mun assist to a Minmus encounter, and get a free return trajectory

Properly planned, this should take <900 m/s of delta-v although I would budget 1000 m/s just in case things go wrong.

[Starman4308]

In theory, so long as you plan and execute your first Mun encounter perfectly, you can get a flyby of every body in (almost*) any order on a single burn of less than 900 m/s. In practice, you're going to need to pack some dV for correction burns, and some flyby orders are going to be easier than others (e.g. it's probably easier to set up a Moho -> Ike -> Dres sequence than an Eeloo -> Gilly -> Bop sequence). The problem with this is largely one of human precision, with a touch of machine precision, as the longer your mission plan is, the more even a slight error in velocity or position will propagate to ruin the planned sequence.

*The Mun has to be first, and the second target has to be easily reachable from there (e.g. Eve, Kerbin), but once you get some orbital energy, you can go nuts. Just... not so nuts that you hit Kerbol escape velocity without a braking flyby set up.

Edited May 25, 2021 by Starman4308

[herbal space program]

17 hours ago, camacju said:

Properly planned, this should take <900 m/s of delta-v although I would budget 1000 m/s just in case things go wrong.

 

1 hour ago, Starman4308 said:

In theory, so long as you plan and execute your first Mun encounter perfectly, you can get a flyby of every body in (almost*) any order on a single burn of less than 900 m/s.

I don't know about in theory, but in actual play I believe the long-standing dV record for just reaching the Jool system was something like 1050 m/s, using a Mun-Eve-Kerbin-Kerbin-Jool route,  and setting up that first Munar assist so the transfers line up is a nightmare.  There's also the matter of the plane change going to Eve, because finding a transfer window exactly  at the nodal point may not even be possible. Having said that, I think the best approach would be to go Mun-Eve-Moho-Eve (brushing past Gilly)-Duna (brushing past Ike)-Kerbin (brushing past Minmus)-Kerbin (alternate Minmus encounter)-Jool-Tylo-Laythe-Vall-Pol/Bop-Tylo-Pol/Bop-Tylo-Dres-Jool (and tylo/Laythe)-Eeloo. The timing is such that the Duna encounter after the first Eve flyby is actually really easy to get if you take the classic E-K-K-J route on its first window, you just need to figure it out so that your trajectory is not much changed when you come out of it. Once you are at Jool, you can use all the gravity assists available there to sling you past everything in the Jool system really easily. Aerobraking at Laythe is also a possibility, but bring some serious heat shielding, because unless you swing by Tylo first you'll be coming in hot! From Jool I think Dres is the next place you'll want to go, ejecting to a 2:1 resonant transfer orbit that encounters Dres at the nodal point and comes back to Jool 10 years later.  From that last Jool encounter, you can eject to an interstellar space-bound Eloo flyby. Alternately, you could try to tag Dres on your way up to Jool, but with the plane change you'll probably have to wait a very long time for that. All told, if I were actually going to try to fly that mission instead of having some computer code feed numbers into MechJeb, I would not want to leave LKO with less than 1,500 m/s in the tank, probably 2,000 TBH, especially if I want it to take less than a thousand years. With what I outlined, it could likely be done in under 100.

Edited May 25, 2021 by herbal space program

[camacju]

3 minutes ago, herbal space program said:

I don't know about in theory, but in actual play I believe the long-standing dV record for just reaching the Jool system was something like 1050 m/s, using a Mun-Eve-Kerbin-Kerbin-Jool route

Getting to Jool for about 850 m/s is fairly routine now using multiple Mun gravity assists, and I've done that many times. My best Jool system encounter used just over 840 m/s and theoretically the minimum is 830 m/s but I've never seen anyone do that. But 1050 m/s is old news.

Additionally, even if you don't use multiple Mun assists, it's better to do Kerbin-Eve-Kerbin-Eve-Kerbin-Kerbin-Jool since you get more control over your orbital period, so you don't need to wait for a K-E-K-K-J transfer window. Plus, it requires a smaller initial burn (you don't need to encounter Eve with as high of a speed since you can get more energy from a Kerbin assist then come back)

5 minutes ago, herbal space program said:

setting up that first Munar assist so the transfers line up is a nightmare

That's why it's better to eject into a resonant orbit with Kerbin using the Mun assist, instead of trying to time the Eve transfer. Then you can swing by Kerbin again to fine tune your transfer. Just leave Kerbin 11 years before the Eve transfer window and the Mun assists will take care of the rest (including plane changes).

If you set up the orbits just right, you could go Kerbin-Mun-Mun-Minmus-Mun-Eve, but that would require a lot of planning for no additional delta-v savings.

[herbal space program]

1 hour ago, camacju said:

Getting to Jool for about 850 m/s is fairly routine now using multiple Mun gravity assists, and I've done that many times. My best Jool system encounter used just over 840 m/s and theoretically the minimum is 830 m/s but I've never seen anyone do that. But 1050 m/s is old news.

........

That's why it's better to eject into a resonant orbit with Kerbin using the Mun assist, instead of trying to time the Eve transfer. Then you can swing by Kerbin again to fine tune your transfer. Just leave Kerbin 11 years before the Eve transfer window and the Mun assists will take care of the rest (including plane changes).

 

That's right, I had forgotten that people set up multiple Munar flybys these days to get more ejection velocity. What are your resonant orbits? Like 6:8 followed by 4:3?  Anyway, that would probably be very difficult to time set up so that you get your Moho encounter out of the way early,  since I think that needs more energy even than K-E-K-K-J, but I guess you could drop yourself down to Moho from Jool at some point.

Edited May 25, 2021 by herbal space program

[camacju]

3 hours ago, herbal space program said:

What are your resonant orbits? Like 6:8 followed by 4:3?

I usually go outward to 6:5, then either pass in front of Kerbin to get an Eve transfer, or go into 4:5 then get an Eve transfer after one more Mun assist. Depends on the position of Mun and initial Kerbin eject velocity

3 hours ago, herbal space program said:

Anyway, that would probably be very difficult to time set up so that you get your Moho encounter out of the way early,  since I think that needs more energy even than K-E-K-K-J

It does, but Kerbin-Eve-Kerbin-Eve-Moho is pretty easy, so I would do that instead. Kerbin-Eve-Eve-Moho is possible also

[herbal space program]

41 minutes ago, camacju said:

I usually go outward to 6:5, then either pass in front of Kerbin to get an Eve transfer, or go into 4:5 then get an Eve transfer after one more Mun assist. Depends on the position of Mun and initial Kerbin eject velocity

It does, but Kerbin-Eve-Kerbin-Eve-Moho is pretty easy, so I would do that instead. Kerbin-Eve-Eve-Moho is possible also

I'm kind of tempted  to give it a try now,  although I would still probably go with 2 km/s once on LKO for insurance against my own ineptitude.  OTOH, I kind of exhausted my patience for this sort of stuff doing the Retrosolar Rescue mission a few years back in a single stage, which took me 200+ years and like 60 separate flybys.

https://imgur.com/a/5URWb

 

Edited May 25, 2021 by herbal space program

[camacju]

Ooh I want to do that challenge now

[herbal space program]

3 minutes ago, camacju said:

Ooh I want to do that challenge now

It was the only time I ever beat Man Eating Ape at any challenge AFAIK, which was the cost required, because I did it in a single stage. I also won the dV contest back then, but I'm pretty sure you could smash that record with enough patience.

[Dr. Kerbal]

Well. If your doing gravity assits I would say 4000m/s. The 2000 into LKO. 1000 to do an Eve Gravity Assists 1000 to make small maneuvers to do other gravity assist and align encounters 

If you dont want to do gravity assists I would recommend 30,000m/dv