Is Duna or Eve easier?

[MedwedianPresident]

I am going to send my first interplanetary probe. Yes, my very first one. I admit I have not been to other planets without cheating yet...only Kerbin, Mun and Minmus.

The question is: Duna or Eve? Both are relatively close to Kerbin, right? And landing is easy on both, Eve because of the atmosphere and Duna because of low gravity, right?

I will send a probe to get the feel for interplanetary missions. Then I will send manned missions.

So...is Duna or Eve easier to get to?

Edited August 13, 2015 by MedwedianPresident

[Randazzo]

If you hit the transfer to Duna just right, it can take only slightly dV more than transferring to Minmus. The insertion burn will vary depending on your approach, but can also be as low as ~550. Ike, it's moon, is also really easy to get to. You can (Relatively) easily land on either Duna or Ike and take off again. The biggest downside to Duna is that it's optimal transfer windows are pretty far apart. (Almost two years I think.. don't quote me, it's pre-coffee morningtime )

Eve on the other hand will take a bit more on both escape and capture burns, and Gilly is in strong competition with Pol for the crappiest vacation spot in Kerbol space. Tiny, hard to encounter, and hates time warp. Eve, while indeed easy to land on if you can avoid burning up, is usually a one-way trip.

This will help plan your transfers: http://alexmoon.github.io/ksp/

[Gaarst]

Well it depends on what you want to do:

If you just want to go there and leave your probe orbiting, I'd say Duna because it doesn't need a lot of dV to get there and you can aerobrake fairly easily in Duna's atmosphere (though it's not dense at all), be ware of Ike (Duna's satellite) that likes to interfere with your trajectories, often leading you where you really don't want to go. On the other hand, Eve has a big sphere of influence but as its atmosphere is really dense, your probe might explode without warning when you enter the atmosphere.

If you want to land your probe, then Eve because if you survive reentry, chutes will be enough to slow down your craft for it to land safely (it has higher gravity than Kerbin so be careful still) whereas Duna's atmosphere is not dense enough and you'll need to brake using rockets before landing.

Finally, if you desire to get back from your mission, then you don't want to go anywhere near Eve unless you're very well prepared with a lander designed specifically for the purpose: the atmosphere is very dense (so lots of drag in low atmosphere), gravity is high (so more dV needed) and Isp asl is simply non-existent for most engines. Taking off of Duna is trivial compared to taking off from Eve.

[Snark]

What the previous posters said. Both Duna and Eve are very easy to get to, and easy to land on.

The two main gotchas for Eve:

- It's incredibly difficult to take off from. It's by far the most difficult body in the game to return from after landing-- it's pretty clear that the designers did it that way deliberately, to offer players an extreme challenge. So if you're sending a manned mission and want your kerbals to come back, Eve should be your final challenge, not your first.

- If you're just landing an unmanned probe, Eve is easy to land on. However, be aware that solar panels work surprisingly poorly there. They work great in Eve orbit (lots of sunlght), but provide very small amounts of power from the surface (something about the temperature and/or thick atmosphere renders them less effective). So if you're sending an unmanned lander, give it plenty of batteries, and expect to need more panels than you'd think.

[Gaarst]

The biggest downside to Duna is that it's optimal transfer windows are pretty far apart. (Almost two years I think.. don't quote me, it's pre-coffee morningtime )

Duna's synodic orbital period is slightly over 2 years (2.13 according to my calculations), so yes transfer windows are fairly rare. Eve's synodic period is 1.6 years though so it's not that of a difference.

And yes I'm quoting you...

[LordCorwin]

Duna drawbacks:

In orbit you'll need bigger solar panels as the Sun radiation is minor.

When landing, you'll need more thrust and more parachutes, as the atmosphere is sparse.

Duna advantages:

Lift off is a hell more easier

Reaching and orbiting the satellite is also more easier.

So I guess it all depends of what you want to do: just orbiting, landing, or making a manned mission and come back to Kerbin.

Edit: it seems that more or less people think in the same way!

Lord

[Sharpy]

Send unkerbed probes to Eve simply to save up more science for kerbed landing on Duna - landing on Duna is about as hard as return from its surface. Landing on Eve is quite easy, with dreadful return. So plan for your Kerbals to visit Duna, no-return probes to Eve.

[Pecan]

I've always thought the biggest problem with getting to Eve is waiting for a transfer window. It's almost the last to come up in a standard game, unless you go immediately (and sub-optimally). If you don't have anything else going on to hang around for you can just timewarp to the transfer though, so it doesn't have to be a deciding factor.

[MedwedianPresident]

I will send a Venera-style probe that only needs to land there. No long term measurements.

[Sharpy]

I've always thought the biggest problem with getting to Eve is waiting for a transfer window. It's almost the last to come up in a standard game, unless you go immediately (and sub-optimally). If you don't have anything else going on to hang around for you can just timewarp to the transfer though, so it doesn't have to be a deciding factor.

Really? Come on, do the 500m/s or so make that much of a difference?

These blue stripes run all the way through the image. There's always a good transfer window to Eve, something under 3300m/s. It's just a matter of time, sometimes you'll arrive earlier if you wait longer. But most of the time you can pick a "today's" transfer window and just launch, never waiting for the distant optimum which would save you some 500m/s or some 100 days of travel.

Now for Duna... Duna has actual transfer windows and periods when you can do nothing but wait or load up the rocket with far more boosters than you planned originally.

- - - Updated - - -

I will send a Venera-style probe that only needs to land there. No long term measurements.

Remember either pretty large solar panels or big batteries. I used some 6 tiny panels and couldn't send some measurements because from dawn to dusk on Duna they were unable to collect enough energy to complete the transmission.

[Pecan]

Really? Come on, do the 500m/s or so make that much of a difference?

No, no they don't. Thank you, I will have to look at transfer-window planners again ..

Aha - I'd never bothered to look at such slow transfers - that makes all the difference

[OhioBob]

Something else that makes Duna transfers a bit easier is that the planet's orbit has a very low inclination of 0.06 degrees, versus Eve at 2.1 degrees. This means that Kerbin and Duna orbit in almost the same plane, which makes it easier to find a transfer trajectory that intersects both bodies. With practice you'll find that it’s not all that hard to get to Eve either, but being this is your first time, Duna is definitely easier.

Edited August 11, 2015 by OhioBob

[Ripper2900]

Buy won't those non-optimal transfer-dv to eve also cause non-optimal captured? Meaning that you'll spend more both to get there, and to stay there?

[Randazzo]

Buy won't those non-optimal transfer-dv to eve also cause non-optimal captured? Meaning that you'll spend more both to get there, and to stay there?

This is true. The more energy you expend on the way out, the more energy you will require on the far end. Eve is closer to the sun than Kerbin is, meaning you'll be accelerating (unless you encounter past periapsis - but you'll still be going faster than when you left Kerbin) for the entire approach.

Of course, you could always try aerocapture at Eve, just be careful it doesn't turn into aerosplatter.

[Cannon]

eve is one of the most difficult challenges for me, so duna definitely

[Mastikator]

Aerocapture on Eve is very hard, the atmosphere is super thick and the escape velocity is higher than Kerbin, so you'll be entering the atmosphere at super high speeds. Even with heat shields and airbrakes it's easy to overheat, without you'll overheat pretty much instantly. At least I did. Entered at low eve orbit only slightly into the atmosphere with the rocket end pointing forward to expend my last ton of fuel inside the atmosphere. Wasn't enough and exploded high in the atmosphere.

Leaving Eve is basically impossible.

[Coga19000]

It is all heavily dependent on the mission of the probe.

If it wants a flyby, Duna is generally easier for a beginner, and hitting Ike during the flyby is much easier than Gilly- do easy in fact, that it will regularly happen even if you don't want it. On the other hand, Eve is not that harder, and it's system will generally give you more science.

If it is going for orbit, well: up until 1.0, Eve was the undisputed winner because of its thick atmoshpere, while now Duna is the undisputed winner- for the exact same reason. It seems that hitting Eve's atmosphere at interplanetary speeds is a guarantee that your craft will implode in a fraction of a second. Most likely will be changed soon, but until then aerocapture is impossible - but aerobraking can still save you some Dv after initial capture.

For atmospheric operations and landing, Eve is generally better ; again, if you don't burn up, you need a miniscule amount of parachutes. However, even if Duna is almost impossible to land on by parachutes, powered landimgs are as easy as on *almost* any airless body (I'm looking at you, Tylo), so it is also a good solution.

Now, if you're a beginner and want a manned mission that will return home, you can simply remove Eve from your brain with a sledgehammer for now. Getting to orbit from Duna is even easier than Kerbin ; getting to orbit from Eve is going to be your crowning achievement after a year or two of KSPing.

[Geschosskopf]

I I will send a probe to get the feel for interplanetary missions. Then I will send manned missions.

So...is Duna or Eve easier to get to?

Duna is BY FAR the easiest planet in the game. It's close to Kerbin so the dV required to go there is small, you can aerocapture at will without fear of reentry heat, so need minimal dV for simple maneuvers within the system. The dV to land and take off again is also small, and you can reduce landing dV even more by using parachutes. It's quite possible to build a non-airbreathing airplane to fly all over the place but it's also quite good rover country. Then it's easy to get back to Kerbin and you arrive slow enough that you can aerocapture there, too (provided you have a heat shield and air brakes). Oh, and while you're at Duna, you can easily go see Ike, too.

Eve, OTOH, is a total pain. Without WAY more heatshield-building effort than it's worth (or turning down reentry heat to about 20%), aerocapture at Eve is out of the question so you'll need about 1500-1800m/s to stop there in a low circular orbit. Landing from there is quite difficult due to the intense reentry heat (shields and airbrakes and maybe even retroburning are required) before you get low and slow enough to use parachutes. Once down, don't expect to get back up again without a HUGE rocket specially designed for that task, so most folks just send 1-way probe landers. Gilly is so small that it's difficult to hit and operations there are a total annoyance because everything happens practically in real time. Coming back to Kerbin isn't all that much harder than from Duna, however.

[Sharpy]

Buy won't those non-optimal transfer-dv to eve also cause non-optimal captured? Meaning that you'll spend more both to get there, and to stay there?

The transfer graphs consider the sum of departure and capture burns for the delta-V displayed.

Check "No insertion burn (e.g. aerocapture or fly-by)" to get just departure burns graph. And you're likely gonna get many much faster cheap transfers that are useless due to high encounter angle = very high capture speeds. Although the optimal transfers should remain the same.

- - - Updated - - -

Aerocapture on Eve is very hard, the atmosphere is super thick and the escape velocity is higher than Kerbin, so you'll be entering the atmosphere at super high speeds. Even with heat shields and airbrakes it's easy to overheat, without you'll overheat pretty much instantly. At least I did.

It's not nearly as bad if you use airbraking very carefully. I went for some 85km periapsis with this:

Ant, Stayputnik, small tank, antenna, thermometer, barometer and three tiny solar panels.

And no control authority whatsoever.

It did perform a capture burn at a very high apoapsis, then I performed some magic bringing the apoapsis even higher, and literally aerobraked from the very edge of its SOI with 85km apoapsis. The bars merely got into orange.

Sure if you dive right in, you're going to burn. But a moderate capture burn aided by very gentle airbraking? Why not?

[Kryxal]

Incidentally, if you want a return trip to Duna, do a fast initial transfer ... you can save a few days for minimal delta-v cost, and that gives you some dwell time and a better return window. Also, use Alexmoon's launch window planner to reverse-plan your trip and see how soon you need to get there.

[MedwedianPresident]

I confirm that I have landed probes both on Duna and on Eve now. Manned mission of course to Duna first.

[cantab]

Really? Come on, do the 500m/s or so make that much of a difference?

http://i.imgur.com/nctkL9V.png

These blue stripes run all the way through the image. There's always a good transfer window to Eve, something under 3300m/s.

But what's the point? Those longer "windows" are transfers that involve making one, two, or more full orbits round the Sun before getting to Eve. You're departing for Eve early, so in Science or Career you're stuck with limited technology and perhaps a reduced set of science instruments and in career you're spending your money now, and you're going to have to wait for ages to get your science and monetary rewards. Why not wait until it's a proper transfer window, and if you did other missions in the mean time you'll have better parts to do your Eve trip with, and won't be waiting for years for the rewards from the mission.

[OhioBob]

I confirm that I have landed probes both on Duna and on Eve now. Manned mission of course to Duna first.

Congratulations. One-way unmanned probes to Duna and Eve where my first interplanetary missions as well. After Mun and Minmus, Duna was also the target of my first manned landing and return. I took things cautiously and performed an unmanned landing/return mission first. Looking back on it, that was probably unnecessary as I'm sure I could have gone straight to the manned landing.

As other have said, a manned return from the surface of Eve is likely the most difficult thing you'll do. I haven't tried it since v1.0, so I don't know how much it has changed. There's less drag now but engines as less effective, so maybe its a wash. It is definitely not a mission for the faint-hearted.

[Mister Dilsby]

My brief opinion:

Duna/Ike is a dream. Relatively easy to intercept and comes around for a transfer window with good frequency. Atmosphere is safe for capture even in 1.0.4, reducing dV requirements. Liftoff from Duna with either conventional rockets or winged craft is easy and getting to orbit requires minimal dV. Ike is close to Duna and easy to encounter, orbit, land and return.

Eve/Gilly, on the other hand, is nothing but trouble. Very easy to intercept and encounter from Kerbin, but there the trouble begins. The atmosphere is positively deadly at entry/escape velocity and yet does not slow a ship down enough to make a difference--you will have to burn engines to capture. Even if descending at incredibly shallow angle from a 90x90 orbit, parts are going to heat up and likely explode. Once you're on the surface....well, that's pretty much where you're going to stay unless you brought a LOT of dV along. And as for Gilly, that little rock is completely annoying. Crazy elliptical and inclined orbit plus low gravity makes it very difficult and expensive to find from Eve orbit. You might think that its low gravity makes it a nice place to visit, but it also means that it takes forever to get down and up--especially since you will be restricted to 1x time warp under 8000m.

For my longer (and highly dramatized) opinions on these two systems, click on the links in my signature

Edited August 13, 2015 by Kuzzter

[Sharpy]

But what's the point? Those longer "windows" are transfers that involve making one, two, or more full orbits round the Sun before getting to Eve.[...] Why not wait until it's a proper transfer window.

You're missing on the fact the axis of the graph are not to scale. The "classic" transfer window to Eve is Year 2, day 350 at 4:04:48 and takes 200 days of travel. Pick a "slow" transfer window at Year 1, day 370 with 500m/s more. 287 days transfer time. Arrival when waiting for fast transfer: Year 2, day 350 Slow transfer: Year 2, day 231 . You get there earlier despite slower transfer because you start much earlier.

And I found "doing other things while waiting for..." the worst kind of procrastination in KSP. I'd spend a week on a single challenging contract or a weird endeavor, that took less than a week of game time! Delaying the launch "because the time is not optimal" could easily lead me to never launching in the end, simply because I'd keep starting new things while waiting for the event to arrive and end up with so many of them that the game time would progress slower than real time constantly!