Jool Explorer Assembly

Blaugust 2015 Day 29

I had planned to spend last night’s gaming time in Champions Online, but the patcher was running extremely slowly, so instead I tried Star Trek Online and it timed out on the character loading screen. Cryptic seemed to be having some kind of network issues, although I didn’t try Neverwinter to see. Instead I took it as a sign to go play more Kerbal Space Program.

In Kerbal, I decided I’d messed around with the planning stages of my Jool mission enough. It was time to start launching rockets. I started with the crew module for the explorer ship. I figured that way I could rendezvous with the hydrogen tanker, dock it, and then dock the engine module with out having to do and undocking and rearranging.

KSP 2015-08-28 22-46-28-01 KSP 2015-08-28 22-46-46-54 KSP 2015-08-28 23-00-09-39 KSP 2015-08-29 00-05-05-52


I took me three tries to get the launch right. I ended up having to go straight up more than I wanted before turning the ship, so I used more fuel getting into orbit than I planned on, but I still have enough fuel remaining to rendezvous. Docking also turned out to be quite challenging. I used more than 60% of my mono-propellant getting into position and closing the remaining distance. A lot of that was due to the mass of the vehicle compared to the reaction wheels and the fact that I didn’t include RCS at the base of the rocket. All of the thruster blocks were on the crew module. I also made the whole process harder by launching when the hydrogen tanker was on the opposite side of Kerbin, so it took quite a few orbits to catch up with it.

The engine module launch when much smoother. The total rocket mass was a bit heavier (387 tons versus 316 for the crew module launcher), but I added extra fuel and engines to the initial stage to compensate and account for a less efficient ascent path. I also saved myself a lot of headaches and waited until the hydrogen tank and crew module were nearly overhead before launching, so I wouldn’t have much work to catch up.

KSP 2015-08-29 00-25-15-56 KSP 2015-08-29 00-31-29-63

KSP 2015-08-29 00-39-25-01 KSP 2015-08-29 01-16-38-08

I only needed one try for this launch. I actually managed a better ascent path as well, although I did still end up in a high orbit than I wanted to. But it didn’t take much fuel to correct that. You can see from the third picture with the fairings off that I sent the engine module up backwards. I wanted to keep the engine and reactor weight at the top of the rocket to help with stability (think of a dart if that’s confusing), and the large docking port that would eventually couple to the crew module was a strong spot to attach to the launcher. Rendezvous was very easy this time since I’d made a better choice on launch time. Docking was also painless, especially compare to the crew module, since the engine module was empty of fuel and only 31 tons where the crew module was fully stocked with supplies and 72 tons during docking.

After completing assembly of the explorer, I transferred hydrogen from the big tank over to the ship. I was able to fully fuel the explorer and still have 66% of the big tank left. The tanker will stay in Kerbin orbit awaiting the ship’s return from Jool where it can refuel for a return voyage or a mission to one of the other planets.

My next play session, I’ll send up the lander vehicle and get it docked to the explorer. It’ll attach to the nose with the hydrogen tanker is currently docked. I’m a little concerned about the thrust-to-weight ratio of the ship once I do that. If it’s too low, I’ll have to make a different transfer vehicle attach to the lander and send it out to Jool ahead of the Kerballed mission. In testing it looked like it would be okay though. There are about 280 Kerbal days remaining before the transfer window, so I have plenty of time to finish assembly and send up the crew.

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