Interplanetary Transfer Prediction

[Duxwing]

How long must I await the return window from each planet to Kerbin? I ask because I use TAC Life Support, which necessitates supplies, the amount whereof I therefore want to know.

-Duxwing

[Taki117]

Have a look at this Website. (Mmmm, Porkchops)

[Duxwing]

Have a look at this Website. (Mmmm, Porkchops)

Thanks. I tested it with a Kerbin->Duna->Kerbin mission with an "Optimal" trajectory and got the following results:

Maneuver_|_Given Time_______________|_Recalculated Time 1_|_Recalculated Time 2_|_Mission Elapsed Time (MET)

K->______|_Year 1, day 231 at 0:14:24_|_Day 456 + 231______|_Day 687___________|_Day 0

->Du____|_Year 2, day 56 at 4:14:24___|_Day 456*2 +56_____|_Day 968___________|_Day 281

Du->____|_Year 3, day 239 at 0:50:24__|_Day 456*3 + 239____|_Day 1,607_________|_Day 920

->K_____|_Year 4, day 79 at 5:26:24___|_Day 456*4 + 79_____|_Day 1,903_________|_Day 1216

This wait is so long and the planets so close that I wonder: can I burn harder to return sooner?

-Duxwing

Edited June 10, 2014 by Duxwing

[Kasuha]

can I burn harder to return sooner?

Not really but you can choose transfer that takes more dv but lasts shorter time.

If you click on Show Advanced Settings, you can set up how big the evaluated window will be. Then just click inside the plot to see alternative transfer.

Edited June 10, 2014 by Kasuha

[Duxwing]

Not really but you can choose transfer that takes more dv but lasts shorter time.

I meant the above.

If you click on Show Advanced Settings, you can set up how big the evaluated window will be. Then just click inside the plot to see alternative transfer.

http://i.imgur.com/ls6VlGE.png

Thanks.

-Duxwing

[Kryxal]

I'd suggest spending extra delta-v to get to Duna sooner ... an extra 50 delta-v could take 60 days or so off the outbound trip, and you'd catch the edge of the return window that way ... you might need 1300-1400 delta-v, but you could spend a few days there and launch for a return without waiting a long time.

Actually, it looks like delta-v costs will rise faster to a point for a later start from Duna, meaning you'll save by a shorter trip there so you can leave sooner.

[Duxwing]

I'd suggest spending extra delta-v to get to Duna sooner ... an extra 50 delta-v could take 60 days or so off the outbound trip, and you'd catch the edge of the return window that way ... you might need 1300-1400 delta-v, but you could spend a few days there and launch for a return without waiting a long time.

Actually, it looks like delta-v costs will rise faster to a point for a later start from Duna, meaning you'll save by a shorter trip there so you can leave sooner.

I like this plan: how shall I effect it?

-Duxwing

[Kryxal]

Check the website linked above, you can select a point and it tells you when to leave and which way to point (honestly, I just set it up with a maneuver node once I have an idea of when to burn). Just have plenty of spare delta-v and be willing to break off if need be without trying to land or anything...

[Kasuha]

A bit of problem with Duna is, window from Duna to Kerbin always slightly precedes reasonable arrival time from Kerbin to Duna.

The solution seems to be a really quick transfer to Duna and then immediate return.

You can go Kerbin->Duna at year 1, day 266 in 100 days for 1566 m/s, then you can immediately go Duna->Kerbin in 200 days for 2281 m/s.

Departure: Year 1, day 266 at 3:14:24

Arrival: Year 1, day 366 at 2:14:24

Time of flight: 99 days 5:00:00

Phase angle: 25.14°

Ejection angle: 153° to prograde

Ejection inclination: -0.10°

Ejection ÃŽâ€v: 1,566 m/s

Transfer periapsis: 13,130 Mm

Transfer apoapsis: 35,441 Mm

Transfer inclination: 0.02°

Transfer angle: 74°

Insertion inclination: N/A

Insertion ÃŽâ€v: N/A

Total ÃŽâ€v: 1,566 m/s

Departure: Year 1, day 366 at 0:00:00

Arrival: Year 2, day 139 at 3:00:00

Time of flight: 199 days 3:00:00

Phase angle: -349.29°

Ejection angle: 167° to retrograde

Ejection inclination: -3.59°

Ejection ÃŽâ€v: 2,281 m/s

Transfer periapsis: 11,423 Mm

Transfer apoapsis: 25,780 Mm

Transfer inclination: 1.43°

Transfer angle: 179°

Insertion inclination: N/A

Insertion ÃŽâ€v: N/A

Total ÃŽâ€v: 2,281 m/s

Figures assume aerobraking.

[Kryxal]

You can reduce the delta-v requirements above if you have more life support by doing a longer return transfer, it all depends on your actual figures really.