Flight of the Starcrane: A Jool-5 Challenge Mission Report

[ChaserGrey]

When you're doing the Jool-5 Challenge Kethane Expedition style, you're doing it on easy mode. So I know I have to bring something pretty impressive to the table to compensate. I'll let you all be the judges of whether I've succeeded or not.

When I stumbled across the Challenge I'd already gotten a 0.23.5 Career save most of the way through the tech tree using MechJeb and NovaPunch 2 for mods, so that seemed like a good place to start. I added Kethane and KAS and got to work, later adding PreciseNode for mission planning.

First up: the lander, which I named Stork. I knew I wanted a single universal lander so I'd only have to bring one set of drilling/refining equipment, and it needed to return a full set of science from each moon I visited. A nuclear engine seemed like the obvious choice, especially one of NP's shorter fusion engines, but I just couldn't get the TWR I needed to lift off from Laythe or Tylo. The solution I came up with was to mount four aerospike engines on radially mounted boosters to act as "afterburners".

In microgravity, she can land on just the nuclear engine for greater efficiency. On Tylo or Laythe, she can light the aerospikes for extra thrust to get to orbit- and since they're aerospikes, efficiency is reasonable at all altitudes on Laythe, which is very much not true for the nuke. It took a fair amount of testing with a full-sized mockup on Kerbin, but by using struts to spread out the landing gear I finally had something I was reasonably sure I could land.

It's not easy to see in the shot I ended up with, but the Stork is actually made up of two modules- the main lander, and a separate section in the rear with the nuclear drive and kethane drill/refinery. That was intentional, because to make the complete Starcrane spacecraft I separated the two and put a "Cruise Stage" in the middle:

The Cruise Stage is mostly a giant fuel tank with some extra drives attached to keep acceleration reasonable. It also had a series of docking ports for the Hitchhiker canisters I planned to attach- 4 total for a planned crew of 6, just to make sure there's plenty of elbow room for the trip out to Jool.

The habs were launched separately on a heavy-lift booster I gave a suitably heroic name to but have been unable to think of as anything but "the wedding cake". They also served to fuel up the Starcrane, since the Cruise Stage burned itself pretty much empty getting into orbit.

Here's the Cruise Stage partially assembled, with two habs attached and a lab module forward. I did the weight calculations out, and it turns out that if you're landing on all five of Jool's moons with the same craft you do save (a little) weight by cleaning out and reusing your Science Jrs. and Goo Capsules instead of bringing extras.

KAS has been a lot of fun to play around with and has made modular ship design a lot easier, since I can dock the modules and then install struts to help brace them. Here Chuck Kerman works the day shift, hooking up the lander module to the Cruise Stage.

And all 4 habs are attached! Since each one was launched separately, I got to put a different flag on each. In addition to the KASA logo, the Starcrane proudly bears the logos of our sponsors: NovaPunch, Kethane, and Squad Development.

And here she is, assembled in all her glory in LKO. Mass, with not quite full fuel tanks, is just under 400 tons.

So where do we go from here?

- First stop will be Minmus. I'm planning to land the entire ship, with the help of KAS anchors winched down from the habs to brace her. The Minmus landing will essentially be a dress rehearsal for microgravity kethane mining/refueling- if there are problems I want to find out about them before we get to Jool.

- Entire ship boosts out to Jool. I'm planning to aerobrake a bit, but have some reserve fuel in case I don't lose as much velocity as I'd like.

- Transfer to Pol. Yes, you read that right. The ship's built to refuel, and I don't want to do that at the bottom of a gravity well. Assuming the Minmus operation went well I'll land the whole ship with anchors and fill her up all at once. Otherwise it'll be a bunch of trips with the lander, but with the Cruise Stage in orbit I'll only be burning a few m/s to and from Pol's surface.

- With the ship refueled I'll have the delta-v to explore Jool system at my leisure. Visit the moons, take samples, get a full set of scientific observations, and move on. Bop is a potential refueling point in the middle, since it also has low gravity. The only major complication is that at Tylo and Laythe I have to hit a kethane deposit the first time I land- the Stork has enough delta-v to land on those moons, but not enough to take off without surface refueling.

- Refuel once more at Pol or Bop before heading home. The lab module has been outfitted with solar panels and a control module, and will be left in Jool orbit for possible use by later expeditions.

- Return home with a full set of science for Jool's SOI and high/low space for each moon. Since I don't have any science from Jool currently I am expecting a ridiculous number of science points that will more than make up for my stupidly large ship.

...Did I mention I've only done one interplanetary transfer before?

Oh well. Ignorance of the laws of physics is no excuse not to try something.

Stay tuned, sports fans!

Edited May 11, 2014 by ChaserGrey

[Speeding Mullet]

That's a great looking ship, best of luck with the mission! I also aero-braked round Jool to line up Pol as the first stop I think it's a good choice.

[ChaserGrey]

That's good to hear. Everyone seemed to be going for Laythe first, but I hate gravity wells.

And a quick update:

With a full crew aboard, the Starcrane departs on her shakedown cruise to Minmus. Check ignition and may Kod's love be with you.