How long do round trips to other planets take?

[Sophistry]

I'm playing a modded game with TAC-LS, and I'm thinking about launching an interplanetary return mission, but I don't know how much life support to take.

I'm only going to Duna at this stage, but I'd rather ask about all the journey times in one go in case there's some kind of chart I can be linked to (and get all my answers now, to save the bother of posting here every time I want to make an interplanetary trip!)

So, in short, my questions are (because I've not noticed this while I've been playing Stock, or with my unmanned missions):

1) How long does the journey take, in each direction assuming I've left at an optimum launch window?

2) Is there any kind of average or theoretical maximum time between arriving at Duna and the next launch window back to Kerbin?

3) Is there any kind of chart or formula for working out the next few launch windows each way based on the date in the Kerbal universe?

4) Can someone point me towards a tutorial for inefficient but faster transfers? (and how to work out/guestimate the kind of delta-V it would cost me, if you're feeling fantastically helpful) I confess I only really know direct transfers!

Edited November 4, 2014 by Sophistry

[Starman4308]

Thine answers lie here. I'd plug in your initial transfer, and use the arrival date as the earliest departure date for the return trip.

There's also a version for 6.4x Kerbin, and probably ones for Real Solar System and 10x Kerbin.

Launch windows are dictated by the synodic period, which is the amount of time for two planets to return to the same angle relative to each other; for Duna, I think the synodic period is ~800 days, so it roughly repeats every 800 days*.

*There are small differences due to Duna's eccentric, inclined orbit.

[Stratzenblitz75]

This launch window planner does just what you're asking. It calculates optimal transfer windows and tells you how much DeltaV you need, when to depart, and how long it will take to arrive.

You can use this info to figure out how long an interplanetary return trip will take.

For example, lets say I'm going to Duna and back.

First, I'll put in Kerbin as the "origin" and Duna as the "Destination" with the earliest departure date being year 1, day 1. (With no insertion burn, since I'm going to aerobreak)

It tells me I have to depart on Year 1, day 58 (Earth Time) and I'll arrive on Year 1, day 121.

For the return trip, I'll put Duna as the "origin" and Kerbin as the "destination" with the earliest departure date being Year 1, day 121, (the Duna arrival date from the first calculation).

For these parameters, I tells me I have to leave on Year 1, day 273 and that I'll arrive on Year 1, day 340.

So, I depart for Duna on Year 1, day 58, and arrive back on Year 1, day 340, which means that I have to carry at least 282 days of life support for the entire trip.

Now, you don't have to use the most optimal transfer. You can click on the Delta-V plot it generates to learn about other potential transfers.

Edited November 4, 2014 by Stratzenblitz75

[Sophistry]

Thine answers lie here. I'd plug in your initial transfer, and use the arrival date as the earliest departure date for the return trip.

There's also a version for 6.4x Kerbin, and probably ones for Real Solar System and 10x Kerbin.

Launch windows are dictated by the synodic period, which is the amount of time for two planets to return to the same angle relative to each other; for Duna, I think the synodic period is ~800 days, so it roughly repeats every 800 days*.

*There are small differences due to Duna's eccentric, inclined orbit.

This launch window planner does just what you're asking. It calculates optimal transfer windows and tells you how much DeltaV you need, when to depart, and how long it will take to arrive.

You can use this info to figure out how long an interplanetary return trip will take.

For example, lets say I'm going to Duna and back.

First, I'll put in Kerbin as the "origin" and Duna as the "Destination" with the earliest departure date being year 1, day 1. (With no insertion burn, since I'm going to aerobreak)

It tells me I have to depart on Year 1, day 58 (Earth Time) and I'll arrive on Year 1, day 121.

For the return trip, I'll put Duna as the "origin" and Kerbin as the "destination" with the earliest departure date being Year 1, day 121, (the Duna arrival date from the first calculation).

For these parameters, I tells me I have to leave on Year 1, day 273 and that I'll arrive on Year 1, day 340.

So, I depart for Duna on Year 1, day 58, and arrive back on Year 1, day 340, which means that I have to carry at least 282 days of life support for the entire trip.

Now, you don't have to use the most optimal transfer. You can click on the Delta-V plot it generates to learn about other potential transfers.

Ah! Wonderful, thankyou guys

Edited November 4, 2014 by Sophistry