Two Vessel Mission into Duna -- and back!

[Moach]

alright, i'm kinda proud of myself for pulling this off (albeit not without the expense of numerous victims valorous crew members)

this morning i managed my first-ever successful Duna landing mission and safe return to Kerbin - unlike the previous attempts that always seemed to end up with somebody left in assorted orbits and/or smeared all over the red surface below...

the mission consisted of not a single craft, but two separate vessels -- the first, was designed with the sole purpose of landing on Duna, then launching back into a low circular orbit (no parachutes or heatshields aboard, to save weight)

the second ship had no landing features - but it did pack a set of three parachutes and an extended cabin (see crewtank mod) to ferry the lucky bastards returning heroes back home....

launching the two vessels had to be done in short sequence - lest we could lose the precious launch window which's next occurrence would be many months away -- once the lander was all set on course, the retrieval craft was sent to follow it less than 15 mins apart

of course, arriving at Duna after 50~60 days of flight, the two encounters were offset by multiple days - this is normal, as can be expected from the minute differences in trajectory upon launch - inevitable they are, given the two craft are considerably distinct designs

the lander arrived at Duna with almost 10 days advantage - so it was just a matter of putting it down... except that it wasn't....

the thing had so little delta-V to spare, a harshly considered (and poorly executed) aerobraking "dive" was the only way to get it to slow down enough for a non-fatal approach.... luckily due to very fine engineering, tho, the whole thing actually worked - and it was put down on Duna's surface with as much as 2 whole seconds of thrust to spare on the tanks

the retrieval craft had no such problems setting up a stable orbit where it could wait out the surface mission in its progress

when all errands had been ran down below, the lander vessel blasted furiously upwards (with the help of three little solid boosters) and established a circular orbit around 80km -- it was all outta fuel after this, so the second craft had to pull out the rendezvous all by itself (using precious return-home fuel)

then i found that orbital sync'ing is quite a handful without that convenient MFD used for this in Orbiter... this was done by trial and error - and gladly was accomplished before need would arise to start planning out a very ambitious two-point rescue mission

with the RCS jets, the crew was able to steady the ship about 30 meters off the lander -- the crew went EVA and boarded the return ship without much fuss... (not considering the fumble with the jetpack controls which required me to go out and rethink my axis assignments)

after all were aboard - the moment of truth, to figure out if they'd have enough juice left to ferry back into Kerbin... gladly they did!

them with a brief burn just short of Kerbin SoI entry, the periapsis was lowered to a reentry-bound 30km (it pays to do these corrections from far off, as you can save a considerable amount of fuel)

whatever i had left on the tanks (not much) was used to slow down for a smoother reentry.... didn't do much tho.... still got just over 5 g's on the ride down (no heat was being simulated but the heatshield was there for good practice, nevertheless)

the 3-chute config proved a little less than ideal with the mass of the extended capsule, and splashdown took place at over 20m/s of vertical speed - if it had been a "touchdown" instead, well... it would not have been a comfortable thing to sit through

alas, i have no pictures to show for it at the moment - this fortunate series of lucky strikes thoroughly planned feat of glory was done at my home rig, in front of which i currently do not sit - perhaps due to reasons stemming from the fact that i'm at work

i'll post pictures of the whole adventure when i get the chance...

next up - doing it again -without- relying solely on sheer luck and seat-of-pants white-knuckle flying

cheers!

Edited October 1, 2012 by Moach

[Nibb31]

Congratulations!

I actually went for a similar approach for my first manned Duna landing. For realism's sake, I didn't want to send kerbals on a one-way trip, and I refused to send a single kerbal in a 1-man capsule and without a hab module. That was just too unrealistic. The mass requirement with available launchers required a two-launch architecture.

The more efficient mission would be a KOR (Kerbin Orbit Rendezvous) architecture, where the two ships dock in Kerbin orbit. This would save mass (only one NERVA engine and hab module would be required), but interplanetary transfers of docked ships is problematic with the current level of docking mods. With our limited docking and refueling capabilities, the best mission architecture I could come up with was DOR (Duna Orbit Rendezvous).

- 3 kerbals with sufficient supplies and life support, meaning a hab module had to be available for each trip.

- Landing 2 kerbals on the ground.

- Use one of the hab modules to serve as a permanent Duna surface outpost for future missions.

- one lander ship and one return ship (although both spacecraft were identical for redundancy and safety).

- two rendez-vous activities at Duna, one on arrival for refueling the return ship with remaining fuel from the lander ship, and the other to transfer crew after returning from the surface.

One of the two identical ships, Dragon-Duna RV. Actually, due to a mistake, the sister ship Dragon-Duna LV didn't get solar panels... You can see the NERVA engine, the hab module, which is designed to be detached and left on the surface of Duna, and the Dragon lander and service module. On the front, there is an Erkle docking ring for the two Duna rendez-vous sequences. The lander ship was flown by Jeb Kerman and Bob Kerman who would land on Duna. The return ship was flown by Bill Kerman, who was to remain in Duna orbit unless a contingency mission forced him to go down and rescue the others.

The dirst Duna rendez-vous went well, but it would have been easier if we hadn't forgot to add an ORDA computer for attitude control. A lot of RCS fuel was spent to rendez-vous because the ships were both quite heavy. However, the essential objective of transferring all the remaining fuel from the Lander ship to the Return ship was achieved, which bought us our ticket home.

After jettisonning the NERVA engine and the (now empty) tank from the lander ship, we deorbited and started our descent. This was a bit hairy. Parachutes turned out to be useless as they only partially opened near the ground, so we had to dump the hab module to maintain our thrust/weight ratio. Too bad for the Duna outpost, but the mission was saved.

Kerbals in awe as they contemplate for the first time a beautiful sunset on another world. Without the outpost hab module, they were a bit cramped inside the lander for the duration of the surface mission.

EVA activities included the (unsuccessful) search for a mysterious artifact and the inspection of an old rover abandoned there several years earlier.

After the visit to the Prometheus rover, Jeb ran out of RCS fuel and had to leg it back to the lander.

Back to orbit, we rendez-vous and docked with the return ship and the crew transferred back to the Return ship.

Farewell lander. You served us well.

Goodbye Duna, we'll be back one day!

Back into Kerbin orbit with enough fuel remaining to circularize.

Which allowed us a pinpoint landing at KSC, just in time for the press conference and the heroes welcome for Bill, Bob, and Jeb.

After pulling off a mission like this, I must admit that I am extremely proud

Edited October 3, 2012 by Nibb31

[etildard]

Very impressive! Mind sharing what mod those parts come from? I've seen people using them quite frequently here on the forums and it looks great!

[LukeTim]

Why can't I do a mission like this?

One day... One day I'll sit down and plan everything out properly... then I'll do a proper mission like this and it'll go off perfectly.

Well done, Moach. Very impressive.

[Nibb31]

Very impressive! Mind sharing what mod those parts come from? I've seen people using them quite frequently here on the forums and it looks great!

Mods included the CbbP Dragon, the Crewtank, Novapunch, the Erkle Docking mod and some other parts from the old Kosmos pack that were home-resized-and-rebalanced (but with realistic ratios).

[sirscott]

I also chose to take the Duna-Orbit Roundevouz approach to my missions. Two of them in fact , for a total of four ships. The program used two types of vessel , the "Dark Star" lander and the "Columbiad" class transfer vehicle. The "Dark Star" is a all-chemical vessel intended to support one crew member only for a maximum of 100 days (any longer and it is assumed the poor kerbal inside will go nuts). What it lacks in crew comfort it makes up for in reliability and endurance. Dark Stars I & II were successfully used to land and return from the Mun and Minmus using stock parts and I got quite used to handling these little craft. Thus when the time came to go to Duna I was loathe to replace them and decided instead to merely add a second craft to the mission profile. The "Columbiad" Is about as simple as Interplanetary craft come , but boasting a 3 man-capsule compared to the Dark Stars single seat. More importantly it is powered by the NERVA engine , allowing a feasible return trip in about 270 days.

The first double mission was intended to be a "Dry run" for a full Duna landing , targeting instead the small moon Ike. This first mission again used stock parts exclusively , lining up the Phase and pro-grade angles entirely by eye. Though I successfully managed to get both vehicles into transfer orbits this lack of precision meant that more fuel then I would like had to be spent on adjustments mid-flight. This in turn meant that after Dark Star III had successfully landed on the surface (see attached picture) it could only manage an orbit of 10,000m or so , far below the intended meeting at 50k+. Fortuitously I had completely underestimated the efficiency of the NERVA rig , and ultimately Columbiad I had more than sufficient fuel to match orbit and transfer the heroic Lolin Kerman. Again , given my human imprecision the closest meeting of the two craft was more than 7000 metres , and there were several anxious moments during the long flight between the two. The ride home was uneventful in comparison , but did allow me to make my first ever Interplanetary-aero-braking manoeuvre. Following this succesfull trial I decided to proceed to the full Duna mission , but with one key addition. I added mecha-jeb modules to both craft to allow for much more precise timing of burns , and to save the F5 button that had been so harshly treated during the Ike Excursion

Anyway , after a standard insertion Dark star IV was parked in a low orbit over Duna whilst Columbiad II was allowed to swing around on a very wide orbit far outside that of Ike. The lander was manually brought to the ground close to the border with the northern polar region , and after after several scary moments my brave kerman walked his first steps upon another world. Alas his little tin-pot lander had few supplies so he was permitted only a day on the surface before returning to a 60km orbit. Mecha-jeb came in very usefull here as its ascent auto-pilot allowed for Inclination matching that of the orbiting Columbiad II , saving the later a considerable amount of fuel. On day 99 Columbiad II was brought into the lower obit , and using the much more precise orbital data provided by mecha-jeb I got it to within 1000m before transferring the landing party. Though much of the return fuel had to be used on re-aquiring the orbital plane the return trip was again succesfull. I didnt have to quick-load once during the second mission , something for which I was very glad.

Anyway , here is a shot of Dark Star III on Ike. Enjoy!

[MaverickSawyer]

Planning a similar mission, but using nuclear-electric propulsion, and a LKO docking before departure. I'll start a new thread for more details and updates, as it will be a long-term mission.

[Moach]

this method of running interplanetary missions not only works, it's actually a little easier to do than trying to somehow cobble up a monstrous beast that do the whole thing all in one push.... perhaps that would work for a one-seat barebones mission, but it's extremely hard to do a more coherent 3-kerbal expedition and get them safely back without some sort of assist from a second (or maybe even a third ship)

i had promised pictures! - i got them here now, so enjoy the view! (note - they're large)

ok, i thought i had more pictures, really... i did manage to forget taking pictures of any of the launches - but nevertheless, both looked a little like this:

cheers!