Duna InSitu - a mission architecture for permanent Duna settlement

[NeilC]

This thread is to show off my entry to sturmstiger's Duna Permanent Outpost Mission Architecture Challenge.

The primary goal of this mission plan is to minimize launch mass by using in-situ resources as much as possible. The Kethane mod provides a way to mine and produce fuel and supplies in-situ, and it will be leveraged as much as possible. No fuel mass should be launched from Kerbin unless absolutely necessary! There's also a strong focus on modularity and re-use to minimize launches. Only 2 big IPTs are launched that can carry up to 5 payloads, instead of a little one for each payload. Only one Kethane tanker is launched, and hangs out on Minmus for the duration. Minimizing infrastructure launches means more tonnage for payloads!

The secondary goal is to maximize early mission score by maximizing launch mass to the first Duna transfer window on day 55. The challenge grants one free lifter on day 10, and the next can follow x*(launch mass) days later, where x=2 for normal lifters or 1.5 for lifters that are at least 50% re-usable. So, a launch interval of 45d and a re-usable lifter gives a payload mass of 30t. See the lifter post for more details.

The only other goal is to maximize score and efficiency by putting the most Kerbals on Duna, and keeping them there as long as possible without incurring the no-return penalty.

I was hoping to go for at least Mission Execution 500, but planning and building has taken me so much time I don't think I'll get to it. 0.21 is calling and will destroy all my in-game work!

Crew and Base mobility? No problem. Put wheels on ALL THE THINGS!

Nods are made to crew safety where possible, like leaving some lifeboats in Duna orbit and making sure every mission has an ascent vehicle to use them. Particularly, the crew's safety is robust to the failure of any single piece of equipment after the arrival of the first IPHAB lifeboat in transfer window 2. But to make the first transfer crew-safety focused as well would have cut way down on the score. After all, challenges are about winning and Kerbals are all about taking unnecessary risks. Just look at how they build rockets. So KSC management decided to screw the crew safety achievement.

The Mission Robustness was easy with a mission plan this modular, and with this many Kerbals hitting Duna in the Day 500 window. In the worst case, a rapid unplanned disassembly of the first IPT/KCV launch, the score would be seriously affected but the mission requirement could still be easily completed in the 2nd transfer window. As long as one IPT/KCT launch (rescheduled as necessary) plus one other launch succeeds within the first 8 launches, the mission is not in jeopardy. if 3/8 succeed, it's even robust to IPT/KCT failure after launch.

Here is the mission plan, see the posts below for module definitions:

Highlights:

34 Kerbals on Duna's surface on day 500

92 Kerbals on Duna's surface on day 1000, with the first 8 having just left orbit. I elected not to bring replacements for them immediately, and instead brought an extra 2xHABEX for more score.

Still, that's 100 Kerbals setting foot on Duna before Day 1000! WOOOOOOO!!!!!

The next 4 launches and the Kerbin->Duna transfer window after day 1000 must be spent launching crew transfer habs for replacement of 36 kerbals at a time (5xIPHAB on a MIRV holds 40, plenty of room). After that all required hardware is spacebound and the mission is running 2 IPTs to capacity just swapping crews. More IPTs must be launched to expand beyond that.

SCORE:

Until Day 0500: 11 Launches, 330 tons NIMLKO, Early Mission Value = 7,332 Efficiency = 22.22

Until Day 1000: 22 Launches, 660 tons NIMLKO, Sustained Mission Value = 43,932 Efficiency = 66.56

Mission Execution 0, Crew Mobility 2, Base Mobility 2, Crew Safety 0, Mission Robustness 2, Achievements Score = 6

Mods: Kethane, IonCross, MechJeb, KW Rocketry, Empty Fuel Tanks, Kerbal Alarm Clock, Crew Manifest, HyperEdit (to partially fill tanks ONLY)

Edited July 28, 2013 by NeilC

[NeilC]

Duna InSitu Lifter

Wet Mass: 153.7t

Dry Mass: N/A

Launch Mass: 153.7t

Capabilities: 82% re-usable. 100% if you ignore some light re-entry. Besides being awesome and mass-producable, it also launches ALL THE THINGS!

Here is an album describing the lifter in more detail.

Edited June 2, 2013 by NeilC

[NeilC]

This large tugboat launches nearly empty:

Wet Mass: 98.7t

Dry Mass: 25.3t

Launch Mass: 41.1t

The lifter can't quite get this circularized, so it carries enough fuel to finish the job. The next thing it does is fly to Minmus, drop the KCT to the surface to mine and refine Kethane, and tank the fuel back to the IPT. Three mining trips and less than 5 days later, it's fully loaded and ready to return to LKO.

Capabilities: 8000+ delta-V when wet. Infinitely refuelable. Able to carry large loads to Duna.

For more details and the mission slideshow, see this album.

Edited June 2, 2013 by NeilC

[NeilC]

This payload contains two modules:

Resource Extraction Ascent Vehicle (REAV), which provides life support for up to 10 kerbals on the surface of Duna. It also serves as an ascent vehicle, capable of reaching LDO from Duna surface. Though not self-powered, it is mobile and can be dragged around by any powered module. As is the trend with Duna InSitu, the REAV launches empty and is designed for on-orbit fueling through the shroud's docking port. It must be refueled slightly before it can land safely on Duna - just a few seconds of thrust are required right before landing to finish what the parachutes start. Once on Duna, it can mine and convert Kethane to refuel itself for ascent, and can ascend/descend infinitely.

HABitable EXploration vehicle, which is a mobile long-term Duna habitat for 4 Kerbals. It can explore on its own for several days before running out of resources, but must dock frequently with a life support module to replenish its O2 supply. Alternatively, it can drag around the REAV on its exploration missions. The HABEX lands via parachutes, plus 8s of retro-rocket thrust to kill its final velocity and land safely - wheel repairs are occasionally required if Bill panics and fires the retros too early. This tiny fuel supply could be replenished by a REAV in case Jeb ever wants to take it off some sweet jumps, but the HABEX will never leave Duna.

The payload shroud is a pure ripoff of sturmstiger's design, with a fairing for aerobraking and drogue chutes to get subsonic quickly. The modules are then dropped with some separation, and land individually. Some ideas are just too good to improve on! The shroud has plenty of RCS for orbital maneuverability and docking, with additional linear RCS ports on the outside of the shroud near the tip (not shown). This maneuverability will become important later.... Actually, the shroud has way too much RCS capacity - the size of the tank is necessary as a spacer for the parachutes and to accommodate the large docking port. For delta-V reasons, this tank will never be full. 100/750 is plenty to fulfill its mission.

Wet Mass: 37.45t

Dry Mass: 29.15t

Launch Mass: 29.15t

EDIT:

So, maybe some of you are looking at the pic above and thinking "Hmmm... that looks a little anemic for a Duna launch vehicle. Is that just 2 LV-909s? Will that really make Duna orbit?" After reviewing my post I sure was. I recalled designing it to 1800 dV, but that was with a small RCS tank for supplies back before adding the big 3t IonCross support system. In the state shown above it's.... broken. Like, <1 TWR and under 1000 dV broken. So, one quick redesign later I give you the lighter, thrustier, more Delta-V endowed REAV 2:

With 3 Vestas and an extra 1m tank stuck in the middle, this will definitely get to Duna orbit with fuel to spare. This exercise also showed me that the IonCross parts aren't that well balanced relative to one another. This uses 4 of the small support modules which each provide for 2 kerbals, so the REAV can now support itself and the attached HABEX even if one of them fails. But each only weighs 0.25t, while the big one to support 10 kerbals weighs 3t. I should really redesign the O2MOD to use these instead, but... meh.

Only downside is the longer REAV needs about 1m more on the fairing to avoid clipping the wheels, which forces it up a whole size, 50% longer. I should be using the new procedural fairings, but again.... meh. I just want to install 0.21!

Revised Payload stats:

Wet Mass: 37.04t

Dry Mass: 28.04t

Launch Mass: 28.04t

Edited July 28, 2013 by NeilC
Updated REAV to... *ahem*... work.

[NeilC]

This payload contains 2 HABEX modules, plus an additional life-support module that provides for 10 Kerbals on Duna's surface.

The O2MOD is towable, and keeps Kerbals alive. It lands via parachute alone. Not much more to it.

Edited July 27, 2013 by NeilC

[NeilC]

Payload 4 is an orbital-assembly workhorse containing 2 modules:

InterPlanetary Tug (IPT) - this is nearly empty at launch, with just enough fuel in the outer tanks for a circularization burn and flight to Minmus for refueling - just like Payload 1. The KCT from Payload 1 remains in orbit around Minmus, so another is not needed.

Multiple Independently targetable Reentry Vehicle (MIRV) - This is a cross-shaped truss to support docking of 5 Duna InSitu Payload modules. In this design, the IPT enters the Duna system and course-corrects for re-entry. The payload modules are then detached, and use RCS to maneuver clear of the IPT/MIRV. This far out from Duna, small separations and dVs mean fairly large differences in re-entry and landing points - on RCS alone the Payloads can maneuver to safely separated re-entry paths. Once the payloads are clear, the IPT/MIRV course-corrects to a non-aerobraking LDO and circularizes there to await the return trip.

Mass: 4.3t

It is always launched with a payload attached in the central position. Shown here is:

InterPlanetary HABitat (IPHAB) - This bare-bones module provides life support and hab space for two 4-Kerbal crews during the interplanetary transfer. It can either launch empty and serve as an orbital lifeboat, or can be launched from Kerbin with replacement crew. On the round trip it returns with any Kerbals who want to leave Duna. It is designed to dock with the REAV to perform crew transfers from LDO to Duna surface.

Mass: 20.1t

Note that the MIRV/IPHAB can be launched together without the IPT as a single standard payload (Mass: 24.4t).

Wet Mass: 76.17t

Dry Mass: 36.17t

Launch Mass: 42t (2 outer IPT tanks 3/4 full)

After orbital assembly, with full Payloads attached:

(Please ignore the wheels visible through the shroud, due to the vagaries of the Subassembly Loader I had to put the HABEX modules the wrong way around. this shot is for mass purposes only, the real Payload 2/3s don't clip the wheels)

In its fueled and loaded state the IPT/MIRV has >1800 dV, and with only the IPHAB attached it has >5800. Transfer from Minmus orbit to Duna SOI, plus maneuvering to put the MIRV payloads in the same hemisphere of the planet as the target site (this is a long-term mobile exploration mission, after all) should take less than 800 dV according to this dV map:

80 to break Minmus orbit

+30 to break Kerbin orbit

+110 to intercept Duna

+370 for Low Duna Orbit (conservative because only the periapsis is adjusted while carrying payloads)

+210 generous safety factor

=800

That leaves 1000 dV on the loaded IPT/MIRV, and with a roughly 3:1 loaded/unloaded mass ratio that should be 3000dV remaining for any orbital maneuvers and return to Kerbin - pleeeeeenty. I know I'm shortcutting the rocket equation calc and ignoring the new wet/dry mass ratio, but I believe since all the jettisoned Payload mass is dry the error should be in my favour - likely hugely so. Point is, I don't think dV for the round trip is a problem here. Correct me if I'm wrong.

Edited July 27, 2013 by NeilC

[NeilC]

so I guess this post is pointless.

Edited July 27, 2013 by NeilC

[sturmstiger]

Launching empty & getting Kethane on Minmus? That's something I've never considered. When I consider ISRU I was mostly thinking of getting Duna ascent vehicle fuel from Duna. If you use this approach for most of you payloads you can potentially save A LOT of mass-to-LKO and getting a very high efficiency score.

Also what's the touch-down / splash-down speed of your spent rocket stages? Are they decelerated solely by parachutes?

Looking forward to see the rest of your plan!

[NeilC]

Good idea to test that out, sturmstiger. I switched it to 3x XL parachutes, and the boosters survive just fine on parachutes only.

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This test makes me think about the O2MOD's survivability on Duna landing, since it's chutes-only too. But I think it'll be fine: there's room for an additional 6 radial chutes around its top, and the landing gear is much sturdier than the LV-T30.

Edited July 28, 2013 by NeilC

[Lazro]

Very cool. I've only sent a 3-crew to Duna. But I did get them back! Without atomics!

[Paul Kingtiger]

Great thread! I'm about to try something similar myself, having just finished Robert Zubrin's Mars Direct.

[sturmstiger]

Congrats for completing your design! I'll need a few clarifications before I put your names on the (first place of the) leader board.

1. Is an IPT launched the Day 100 launch? You said the dry mass of the IPT/MIRV/IPHAB payload is 36 ton, which your 30 ton LV would not be able send to LKO. If you fuel (partially) the IPT and use the IPT for the circulization burn, are you sure the 2 NERVAs provide enough thrust for that burn?

2. Are the RCS fuel tanks just outside of the payload fairings considered fuel or life support supplies?

3. How does your O2MOD provide enough supplies for Kerbals for the Kerbin->Duna transfer and Duna stays? Note that it would not be able to extend the solar panels when enclosed in payload fairings.

[NeilC]

Congrats for completing your design! I'll need a few clarifications before I put your names on the (first place of the) leader board.

1. Is an IPT launched the Day 100 launch? You said the dry mass of the IPT/MIRV/IPHAB payload is 36 ton, which your 30 ton LV would not be able send to LKO. If you fuel (partially) the IPT and use the IPT for the circulization burn, are you sure the 2 NERVAs provide enough thrust for that burn?

2. Are the RCS fuel tanks just outside of the payload fairings considered fuel or life support supplies?

3. How does your O2MOD provide enough supplies for Kerbals for the Kerbin->Duna transfer and Duna stays? Note that it would not be able to extend the solar panels when enclosed in payload fairings.

1) Yes, the IPT is launched on Day 100, and is partially fueled to complete its own circularization burn. I am 100% confident this will work as I proved it out for the IPT/KCT day 10 launch: a partially fueled IPT can take 41t all the way to Minmus with fuel to spare. The launch mass of the day 100 IPT/MIRV/IPHAB is 42t, and it drops off the IPHAB in LKO before heading to Minmus.

2) They are RCS, I am using IonCross as a substitute for the supply rule so no supplies are used anywhere.

3) Good point, my plan was definitely to have the O2MOD operational for the transfers. There is spare mass for solar panels on the payload shrouds (after revising the REAV, the 2xHABEX is heaviest at 28.04t), which I really should have put on there anyway to keep the probe body powered. Can we just say I did that, or do you want to see pictures?