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Interplanetary Transfers - They take years?


Freyera
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I did all the calculations for the Hohmann Transfer from this thread, got it all right, used Hyperedit to put myself in Kerbal Orbit, did the proper burns at the proper times, and hit the planet smack dab on the mark.

My question is, it took FOREVER to get to the point of hitting the planet. The Duna Phase Angle was 45 degrees, and it took Kerbal nearly 300 days to get there. Is this just how it's supposed to work?

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I did all the calculations for the Hohmann Transfer from this thread, got it all right, used Hyperedit to put myself in Kerbal Orbit, did the proper burns at the proper times, and hit the planet smack dab on the mark.

My question is, it took FOREVER to get to the point of hitting the planet. The Duna Phase Angle was 45 degrees, and it took Kerbal nearly 300 days to get there. Is this just how it's supposed to work?

Yes, it is.

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I just started playing again with 1.0 (haven't really played much since 0.25). Did they ever add anything in game to determine launch windows?

I'm playing in career mode and haven't unlocked everything yet, so I have no idea if such a function exists in game. Or do I have to continue using 3rd party websites for this function (or eye ball it)?

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Yep, the missions could take years, even on this scale. In real life, the New Horizons probe we sent to Pluto has been traveling for 10 years now and it's going to encounter Pluto in July. That's a long time.

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The Duna Phase Angle was 45 degrees, and it took Kerbal nearly 300 days to get there.

Yes, as should become obvious when you watch Kerbin and Duna move around the Sun in fast-forward. A good alignment happens only once every 2.2 Kerbin years or so. That's over 1000 Kerbin days.

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From the Hitchiker's Guide to the Galaxy, "Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space."

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Yes, "good" transfer orbits rely on a specific alignment of the planets, and take significant fractions of a full orbit to complete. Fortunately, it's possible to cheat - if you have more than the bare minimum amount of delta-V, you can take a less optimal path to Duna without waiting as long for a transfer window or taking as long to get there.

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Yes, "good" transfer orbits rely on a specific alignment of the planets, and take significant fractions of a full orbit to complete. Fortunately, it's possible to cheat - if you have more than the bare minimum amount of delta-V, you can take a less optimal path to Duna without waiting as long for a transfer window or taking as long to get there.

Taking that a step further, there's a fun topic on the challenge forum where people specifically attempt to make the fastest possible trip to other worlds. I managed to make it to Duna in only 16 days 3 hours and 35 minutes. You can see my challenge entry here. This is the far extreme of using an extremely high amount of DV to accelerate fast enough to make for a shorter trip. The transfer window planners go for the opposite: they give you the point to launch that uses the least amount of DV, but you can find a happy medium if you want.

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(Off the top of my head so quite possibly wrong): The right planetary alignment for the Voyager probes only comes around every 175 (Earth) years or so. It's often more when you can go rather than the time it takes to get there.

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I just started playing again with 1.0 (haven't really played much since 0.25). Did they ever add anything in game to determine launch windows?

I'm playing in career mode and haven't unlocked everything yet, so I have no idea if such a function exists in game. Or do I have to continue using 3rd party websites for this function (or eye ball it)?

Sadly they haven't yet, it's probably the single biggest "missing" feature for me. There was a really good suggestion made in the ideas forum about adapting the maneuver nodes system so it could be used in the tracking station. Basically you would be able to place a node on the orbit of a planet like you can currently do on the orbit of a ship, then target another planet and edit and drag the maneuver like normal.

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Yes, "good" transfer orbits rely on a specific alignment of the planets, and take significant fractions of a full orbit to complete. Fortunately, it's possible to cheat - if you have more than the bare minimum amount of delta-V, you can take a less optimal path to Duna without waiting as long for a transfer window or taking as long to get there.

I never bother with launch windows, they are too much trouble. I just put my craft barely on the appropriate (inward/outward) Kerbin escape trajectory and then make my maneuver node for the transfer once I'm out of Kerbin's SOI. It usually means a bit of a wait for the transfer but it works.

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I never bother with launch windows, they are too much trouble. I just put my craft barely on the appropriate (inward/outward) Kerbin escape trajectory and then make my maneuver node for the transfer once I'm out of Kerbin's SOI. It usually means a bit of a wait for the transfer but it works.

But it's inefficient, afaik it's best to do the whole burn to your target in one go dv wise. I usually do it from LKO using MJ as it has a brilliant, colourful porkchop plot which lets you decide when you want to start the burn, when you want to arrive and the dv required to do so. Probably the best feature MJ has.

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If you have a huge amount of dV, you can avoid elliptic transfer and travel straight. Should be faster))

The problem then becomes slowing down at your target, and not just shooting straight past it. Since 1.0, unless you have aero turned off, aero-capture is out, unless you have a couple hundred heat shields, or a heap of left over dV.

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Since 1.0, unless you have aero turned off, aero-capture is out, unless you have a couple hundred heat shields, or a heap of left over dV.

Aerocapture is still 100% possible in 1.0x, even at higher velocities. One heatshield should be more than enough for any duna capture (and if you're doing a low-energy transfer you probably won't need it at all). Jool and Eve are more tricky, but as long as everything's behind a shield, you should be just fine. The margins for your periapsis are a heck of a lot smaller than they were in the old aero, but it's definitely still possible (and useful). People have been doing this for years with Deadly Reentry and the new stock heating is much more forgiving.

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