Optimal Jool Space Station Orbit

[skaterzero807]

I recently set out to answer a question I had about where to put a space station around Jool in order to minimize dV requirements for future craft and wanted to share my results since it was not something I could reason out.

The goal was to minimize dV required to rendezvous with the station, then get into circular orbits around Laythe, Vall and Tylo while returning after each trip for refueling/science processing. The cost includes getting from an aerobraking Jool orbit to the station orbit, then getting to a circular orbit around each target and returning to the station. No landing/takeoff was considered since it would be the same regardless of where the station was located.

Anyway, the short answer is to put your station in a low Laythe orbit (55-60 km). This solution requires more dV to get to Vall and Tylo, but is worth it because coming back from Vall and Tylo is cheap with aerobraking. Also going to Laythe is very cheap when you are already there .

More info on my project page. Here is the plot of total dV vs. location for anyone interested:

A few interesting things to note about this plot:

1. DO NOT aerobrake around Jool to get into low Jool orbit. It costs way more to get to the moons than you will save aerobraking at Jool to return.

2. Getting inside an SOI decreases the dV required to travel around. If you don't want to visit Laythe the next best place to be is inside Vall's SOI.

3. Being close to an atmosphere-less body is not good unless you plan on making many trips to that body.

[juanml82]

Good to know. I have a flotilla on the way to Jool and I'm sending two tankers and one mobile lab along. One of the tankers is supposed to refuel a Tylo lander though, so I guess that one doesn't benefit from a Laythe station.

[cantab]

In pure delta-V terms, wouldn't an elliptical Laythe orbit be even better, since it would require less delta-V to escape from? It would be a practical nuisance mind, since you'd be limited in suitable ejection and entry angles.

Also, while the landing doesn't matter for delta-V usage, it will for fuel usage. Say your station is at Laythe, then for the Laythe landing you just need to fuel to get the lander down and up, but for the Vall and Tylo landings you also need the fuel to ship the fully-laden lander to its target, and if desired to ship the empty lander back to the station. For a fixed on-the-ground payload, the Tylo lander's going to be the heaviest, not sure about Vall vs Laythe.

[merendel]

In pure delta-V terms, wouldn't an elliptical Laythe orbit be even better, since it would require less delta-V to escape from? It would be a practical nuisance mind, since you'd be limited in suitable ejection and entry angles.

If your willing to take the time for it sure it would be cheeper but you prety much have to always come into lathe's SOI from the same direction to get your PE to line up with the stations. You'll waste a ton of fuel if you need to correct that. you'd also have to wait till lathe moved into the correct position to eject on a prograde vector and depending on where your at in your orbit that may not line up very nicely with your destination. Probably more trouble than its worth IMO. Personaly I still favor tylo for my stations. bit more expensive if you go direct burn departures but tylo's an easy target to hit and really easy to set up a cheep departure that gets a gravity assist an orbit later to kick up/down to your desired orbit without useing as much fuel.

[skaterzero807]

Yes, I haven't run simulations for elliptical mainly because getting the longitude of periapsis lined up would probably be a pain, as well as timing the SOI exit to result in the correct transfer orbit at the right time to intercept the target.

Also, cantab, you bring up a good point about sending all that fuel to Tylo and back. I might look into optimizing this based on minimizing the amount of fuel required on each journey and back, or even to minimize the difference in fuel amounts so you can visit everywhere with the same craft.