Explore - "Return from <body>" Contracts

Srpadget · February 23, 2017

A standard element in "Explore" contracts is the "return from" subcontract. When I've done these before, for Mun and Minmus, I've always done it with one-shot crewed vehicles, so I've always brought back both a kerbal and (part of) the vehicle. So I've never really had to be that careful about the fussy details of what the contract is actually looking for.

Now I find myself going off to strip-mine the Duna/Ike system--with reusable vehicles and leaving a colony's worth of permanent infrastructure in place. I plan to bring back several crew, but no vessel part that's ever been in the Duna SOI is planned for return to Kerbin's surface. (The return vehicle is a deep-space tug: it will dock at orbiting stations around Duna and/or Ike, then come back to Kerbin ORBIT, and the final return to Kerbin's surface will use a Kerbin-local SSTO.)

So, what does the game want/expect to see in these "return from" contracts? I've gone back through my archives and looked at the verbiage in my completed Mun/Minmus "return from" contracts, and they are...ambiguous.

WanderingKid · February 23, 2017

9 minutes ago, Srpadget said:

So, what does the game want/expect to see in these "return from" contracts? I've gone back through my archives and looked at the verbiage in my completed Mun/Minmus "return from" contracts, and they are...ambiguous.

A component of a craft (NOT a Kerbal) that has been to that body (landed, in orbit, whatever) returned and recovered on Kerbin's surface. An experiment can loaded with the local science fulfills this.

Srpadget · February 23, 2017

Well dang. I'm hosed then.

I guess there's nothing for it but to send a "return contract fulfillment package" that consists of nothing but a couple docking ports, just so I can carry it down to the surface attached to the lander, bring it back up and attach it to the return vehicle, transfer it to the crew lander in LKO, and return the ports to the surface.

(Or I could just "cheat" the contract as fulfilled once I've brought back kerbals with bags full of rocks. I mean, by the game's standards, humans have still never returned from the surface of the Moon--the Apollo command module only returned from Moon ORBIT, after all.)

Streetwind · February 24, 2017

16 hours ago, Srpadget said:

I guess there's nothing for it but to send a "return contract fulfillment package" that consists of nothing but a couple docking ports, just so I can carry it down to the surface attached to the lander, bring it back up and attach it to the return vehicle, transfer it to the crew lander in LKO, and return the ports to the surface.

Why so complicated? You literally only have to return any part that has fulfilled the contract stipulation. Even if your contract says "return a craft from the surface of Duna", that can be done far easier. Especially if you have no plan to return any science,

Here, I was bored and thought this was an interesting engineering problem, so I whipped this up with the help of the wiki:

1x size 0 heatshield    0.075
1x Mk12-R radial drogue 0.075
-----------------------------
stage 4 = 0.15t


1x stage 4               0.15
1x size 0 decoupler      0.015
1x okto2 probecore       0.04
2x ox-stat panels        0.01
1x size 0 reaction wheel 0.05
1x mk2-R radial chute    0.1
1x fl-t100 fuel tank     0.5625
3x lt-05 micro legs      0.045
1x round-8 fuel tank     0.3375
1x spark engine          0.1
-------------------------------
stage 3 = 1.41t wet, 0.61t dry
2630m/s vacuum dV
4.6 initial Duna-relative surface TWR


1x stage 3             1.41
1x size 1 decoupler    0.05
1x size 1 fairing base 0.075
1x fl-t800 fuel tank   4.5
1x terrier engine      0.5
----------------------------
stage 2 = 6.535 wet, 2.535 dry
3200m/s vacuum dV
0.95 initial Kerbin-relative vacuum TWR


1x stage 2           6.535
1x fairing walls     0.215   (very pessimistic guess that results in a nice round stage mass number)
1x size 1 decoupler  0.05
2x adv nose cone     0.15
3x bacc srb         22.95
--------------------------
stage 1 = 29.9t wet, 11.45t dry
roughly 1700-1750m/s mixed ascent dV
tune initial TWR to taste, let center burn out first to smooth out acceleration curve

30 tons to Duna and back. Could be lighter using a liquid first stage, but SRBs are cheap.

Stage 1 and 2 do Kerbin ascent (3400 m/s), stage 2 does Duna transfer (1100 m/s), vessel aerocaptures at Duna, aerobrakes into descent, uses remainder of stage 2 (~400 m/s) to slow down into safe parachute range, slows down further with parachute, cuts parachute and propulsively lands with stage 3 (~400 m/s budgeted), stage 3 performs Duna ascent (1400 m/s) and Kerbin return transfer (750 m/s) into direct aerocapture, stage 4 aerocaptures and aerobrakes into descent, parachute is auto-staged at time of decoupling from stage 3.

Super rough design, probably can and should be refined. Potential issues: not much control authority during stage 1 burn, designer is unfamiliar with this kind of EDL at Duna, margins may be tight.

But hey, why bother with juggling docking ports from one vessel to another when you can just lob a parachuted heatshield in Kerbin's general direction?

Edited February 24, 2017 by Streetwind

Srpadget · February 26, 2017

On 2/24/2017 at 2:43 AM, Streetwind said:

Why so complicated? You literally only have to return any part that has fulfilled the contract stipulation.

What, adding a dual-docking-port bit is "so complicated"? Tacking on a little pointless extra like my "two docking ports" is as close as I can come to a ZERO extra effort solution. In my original post, I noted I was leaving "a colony's worth of permanent infrastructure in place". Maybe i should expand on what I mean by that.

[TL;DR version of the below: I'm already doing lots (...and lots...and LOTS...) of docking. If I'm already docking A to B and then undocking, having a little widget that starts on A but ends up on B is ZERO extra complication/bother.]

17 launches to LKO. Some LKO assembly of the Ike and Duna orbiting stations before I chuck 'em at the Duna/Ike system. Result is 14 interplanetary vessels all getting sent on independent interplanetary trajectories during the same launch window. Once everything is sorted out at the destination, I have: full comsat systems around both Duna and Ike; permanent ISRU mining base on Ike with support vehicles (fuel tanker rocket, ore tanker rocket specifically to pick up the "transport ore from Ike to Duna orbit" contract that more than pays for the entire flotilla, and tanker trucks to shuttle fuel/ore between the ISRU base and the aforementioned tanker rockets); the prospecting satellites and rovers which get abandoned in place once the ISRU site is selected; orbiting science/refueling stations around both Duna and Ike; a couple in-system transport/tugs that never land but shuttle back and forth between Duna and Ike orbit, and landers for each world that cycle between surface and low orbit--23 separate vessels doing their various things in Duna/Ike space and never coming back. Plus of course the return vehicle, which IS coming back, but only as far as LKO, where it's met by an SSTO that takes the returning crew back down to KSC along with their bags of rocks (plus, now, some docking ports that get transferred along with the returning crew).

[It should be obvious at this point that I'm a "flotilla" guy, not a "huge mothership" guy'. And an "infrastructure" guy, not a "flags-and-footprints" guy. It should also be obvious that I'm not doing this JUST to fulfill an Explore contract. I don't even HAVE the "Return" contract yet. But we all know I *will*. The way the Explore progression has been rewritten, I'm going to HAVE to fulfill "Return" contracts--as well as "dock in orbit" contracts--for both Duna and Ike surface, before I start getting offers for Jool or Eve. So I'm trying to plan ahead. Frankly, I view many of these required Explore subcontracts as annoyances to be minimized, not as opportunities.]

All the planned surface-to-LKO launches were completed, but the flotilla not yet sent on its way, before it occurred to me that the contract system might want to see PARTS returned rather than just Kerbals and bags of rocks. And NOTHING is capable of Kerbin reentry. Nothing in that flotilla that ever touches the surface of either world is ever intended to come back to Kerbin SOI. So, no matter what, I have to launch SOMETHING from Kerbin surface to LKO; from there I either dock it with one of the existing vessels or send yet another craft off on an interplanetary trajectory. And, really, a docking in LKO is much simpler and less hassle than flinging YET ANOTHER independent craft to Duna, so I can reenter/land it on Duna, and then fling it back to Kerbin for the return trip... just to get hit with a "return something from IKE this time" contract once I'm done.

On 2/24/2017 at 2:43 AM, Streetwind said:

why bother with juggling docking ports from one vessel to another

Because I'm already doing multiple dock/undocks in Duna/Ike space as part of the base mission profile, and my scheme adds precisely ZERO additional steps after the initial launch. (And there's got to be a launch of SOMETHING that can return to Kerbin surface--even if, as you note, it's just one part.) So, other than the initial launch of "part to be returned", the ONLY added "bother" is that there are a couple times where I need to pay attention to exactly which docking port I click on to bring up the context menu with "undock". I'd be clicking "undock" anyway, mind--it's just that now I'll have to pay a bit more attention to which port I'm pointing at when doing so. Added bonus: my way, the docking ports can follow Jeb around, and land on both Duna AND Ike before coming back; this should prevent EITHER of those Return contracts from darkening my doorstep beyond this single launch window.

Streetwind · February 27, 2017

11 hours ago, Srpadget said:

In my original post, I noted I was leaving "a colony's worth of permanent infrastructure in place". Maybe i should expand on what I mean by that.

Ah? Sorry, then I read to much into "no vessel part that's ever been in the Duna SOI is planned for return to Kerbin's surface" bit. It made it sound like you physically don't have any hardware you can bring back, because you need all of it where it is, and instead need to launch something new from Kerbin no matter which way you turn it.

If you already have something on Duna that isn't required for the colony to keep running, that is of course the lowest effort solution of them all.

Edited February 27, 2017 by Streetwind

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Explore - "Return from <body>" Contracts

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