How Edley Kerman walked the sands of Duna and returned home to tell the tale

[Newman]

(Stock only)

I doubt I'm the first who's thought of this, but I haven't played KSP for some time now and checking again on the forum yielded a pleasant surprise - new planets, exactly what I've been waiting for! After a few spectacular failures I managed to finally do one-way trips to Duna and Eve. Problem is, one-way trips rub me the wrong way, and even a one-way trip to Duna I found to be harder than a return trip to the Mun. The target planet is much further away, requiring lots of fuel, it has a much higher gravity than the Mun, meaning that landing a ship that has enough fuel for a return trip isn't practical (frankly, such monster rockets usually disintegrate on the launch pad for me).

So, I came up with another way - I'll launch two craft to Duna; one will be an orbiter with the bigger, three-seater pod. Since this ship doesn't need to land, I can just give it a massive interplanetary stage with nuclear engines instead. The other ship will be a one-seater craft that will be able to land on Duna, than take off again, perform and orbital rendezvous with the orbiter, transfer the crewman to the orbiter via EVA, and then return the orbiter home.

Part 1: Securing our return ticket

This is how it all went.. perhaps it can help someone do the same. Before I begin though, I don't claim that this is the best or only way to do this - but it worked for me. I'll also include the .craft files below in case someone wants to try it with the same ships I did it with. Note that I haven't used any mods at all - the game was as vanilla as it gets.

First I needed to design the craft to do it. Even the two-craft approach meant building rather massive rockets, as you're about to see:

The Duna Orbiter Mk I on the launch pad. You'll notice only two crewmen on the screenshots - I had one EVA on the launch pad, and then I did an "end flight" for that crewman only. This provided me with an empty seat needed to recover the kerbonaut that would be landing on Duna.

It actually flew surprisingly stable! I learned my lessons with the Duna series of rockets, where Duna VI was the first to reach Duna and Duna VIII finally became capable of re-establishing orbit after landing.

..establishing orbit. I spent the almost the entire first series of tanks of the interplanetary stage to do this. But, I expected this.

The thing that will make or break your trips is efficient trajectory planning. It took me a few trial and error runs to figure out how to do it without spending too much fuel. Before you even attempt this, however, you should be familiar with KSP basics; you should know how to modify your orbits, change orbital inclination, and having performed several orbital hook-ups before helps too. Once your map view shows that you're on the way to Duna encounter, check the projected periapsis to Duna. Due to extreme distance, it's probably a rather large number, say 25 million km away from it or so. The problem with that is, if we stick to this course it will take us way too much fuel to slow us down once we get to that point. Now it's time to put to use all that knowledge about modifying orbits - burn a tiny bit prograde/retrogade to get the periapsis as close as it will go, then wait until you get about halfway of the projected path to Duna. Once you're half way there, modify your orbital inclination a bit if needed - I was usually able to bring my periapsis down to say, 250-450km away from target planet. These correction burns are tiny and don't cost much fuel at all, if done at these large distances. Once you get to Duna, correcting large mistakes will cost you so much fuel it'll usually be enough to ruin the whole mission. So, do tiny correction burns at a distance until you have a proper approach set up, and you'll end up here soon enough:

Duna Orbiter Mk I, orbiting Duna. What it was made for. Now it's time for stage two of our mission. Switching back to the space center, I prepared to launch the Duna VIII, the ship that will actually deliver a crewman onto the surface of Duna. That's up next..

Edited September 23, 2012 by Newman

[Newman]

Behold the Duna VIII! I really designed this one to *just* have enough fuel to pull it off. If you plan your route efficiently, it'll be plenty enough though.

Again, flies surprisingly well considering the size of the thing. Time to get it to orbit, and say hi to an old friend:

I remember when getting to the Mun and back was the ultimate challenge

Again, planning a low consumption route and not wasting a bunch of fuel on chasing Duna all around the system is the name of the game.

Getting close...

Setting up for atmo entry...

And planning our descent trajectory. I equipped the lander with 5 chutes, but they're not near enough to do the job. First of all, Duna's atmosphere is really thin and only begins at some 42km above surface. Relying on just the chutes just means making another crater. Secondly, our lander is way too massive for the chutes to handle on their own - and you really don't want to use the chutes to kill your horizontal velocity; you need to use your engines to control your descent. Make sure you don't come in too fast when the chutes deploy, either, and be prepared to assist the chutes with engines sporadically all the way until touchdown.

Here goes nothing...

Final burn to slow us down...

... and that definitely earned us the rights for some Duna-themed tacky postcards

Duna. Land of sand.. and of the spice mel.. or was that something else?

Just in case it wasn't, better go back in - the Sand Worms come out at night and I don't have an ornicopter to warn me.

Up next, the triumphant return

[Newman]

I used up the few drops of fuel left in the descent stage to gain some altitude, ditched it, and then used the ascent stage to get back into orbit:

This is where the orbital matching skills come into play. I didn't have the fuel to do the fancy linkup with one ship a few meters away from the other, but getting close enough for a suit transfer was all I needed, and this orbit provided that shot:

Time to abandon our faithful Duna VIII - by this time it was all out of fuel (RCS as well), but it served me well. It will now stay in orbit of Duna as a permanent monument to Kerbal's first steps on another world. Well, first Kerbal that went back home and lived, anyway.

Using the suit's RCS jets, I made my way towards the Orbiter Mk I that's been waiting for me for the entire time.

Really need to get to Duna's moon some time as well...

..and here we go.

That's it for the hard part. You may have noticed that about 3/4 of Orbiter's interplanetary stage fuel is gone. But the rest is more than enough to return to Kerbin.

Again, we need an efficient return trajectory.

..and soon enough we find ourselves back on the planet we started from.

With all fuel spent, it's time to ditch the interplanetary stage and use RCS to plan my descent. I like to land on water, so as to not break my Kerbonaut's spines... but I also like to put them in somewhere close to land, in a bay if possible. Much better than dropping them in the middle of an ocean!

Location selected, going in.

..and the rest is self explanatory. I love the view of the chutes from the cockpit window

Rule #1 of water splashdowns: if you can't see land from your window, you've failed.

Back home! Edley Kerman became the first Kerbal to walk on another planet and return home (in my game, anyway )

Edited September 23, 2012 by Newman

[Newman]

Here are the .craft files for both ships used.

[chrislo27]

Wow! This is amazing, compared to my horrible landing and flight skills (and I joined in 0.8.4!). This ultimately gets my seal of approval.

[pyro1997]

Great Scott! I had to use a 0 fuel usage engine to chase eve all over, and I still cannot get to it, I am sad. T-T

[Newman]

Great Scott! I had to use a 0 fuel usage engine to chase eve all over, and I still cannot get to it, I am sad. T-T

Getting to Eve is merely getting from a point in a higher orbit to a point in a lower one - so you can apply the same principle I used to return from Duna (there are screencaps that show the return trajectory above). Since Eve is in a lower orbit than Kerbin, it orbits the Sun at a much higher velocity, therefore you will need to apply a retrogade burn while you're still ahead of it along the orbital path. There is one small complication with Eve, though - it's orbit is inclined a few degrees relative to Kerbin's - not much, but just enough to miss it, so you will need to correct for that first. The way I do it: after achieving orbit I do a Kerbin escape burn. This puts me on a similar orbital path around the Sun as Kerbin. Now I wait until, from the side view on the map, my orbital path seems to intersect that of Eve's - at this point you do an inclination correction maneuver so your orbital plane is more or less parallel to that of Eve's. Now you need to wait until you're, say, 30 or 40 degrees ahead of Eve on your orbital path, and apply a retrogade burn until the map view shows up Eve encounter. Now you adjust your periapsis with tiny prograde/retrogade burns to get to Eve as close as you can get it, then wait until you're half way there, then slightly adjust your inclination (tiny burns, again) until your periapsis is a few hundred km away from Eve. Considering Eve's thick atmosphere, you could consider aerobreaking to save fuel on slowing you down - when you get closer you could adjust your periapsis to, say, 70km altitude to assist you in your breaking maneuver.