KSP update time! (He said with glee.) You EVE players may move on to the next post.
I'm still kind of "between major missions" after the end of my Duna mission last month. But I'm still playing around with more minor KSP missions. On a lark (and because it was more or less positioned perfectly), I decided to forgo installing any mods just yet and try for one more interplanetary mission. This time, the target was Dres and the mission would be another unmanned Pathfinder probe.
Learning from the lessons of Enterprise's mission to Duna and its return trip, I decided to do this one with eight "-16" size fuel tanks, six of them on a main injection booster, two of them on an orbital insertion booster, and then a tiny probe on top. I knew from the success of the Duna transfer orbits that this would be sufficient fuel to make the journey to Dres and the important orbital injection on the other end. Also learning from Enterprise's mission, I fitted the upper stage with large docking ports for refueling the mission and "junior size" docking ports for attaching two mini-probes. The eventual spacecraft looked pretty cool if I do say so myself, particularly with one of my automated heavy refuelers docked to it.
Docking was a breeze, and there was enough left in the refueler that after the Dres probe was refueled I sent the fueler up to Liberty station and emptied the rest of the main tank there. Then I used the RCS thrusters and the remaining monoprop to bring the refueler home for a safe splashdown. Taking advice given to me in my last KSP post, I had eight parachutes on the refueler but set the altitudes on them such that they would open in pairs every 500 feet. Thanks to the slower deceleration shock at each parachute opening, the resulting spacecraft didn't break apart despite being complex. Thank you for that tip and plus one for "reusable" spacecraft!
Off the probe went to Dres and the final insertion burn was smooth and relatively pain-free. The resulting low mass spacecraft had no problem with the burns and I still had sufficient fuel left for orbital maneuvering once I was in Dres orbit. I undocked one of the mini-probes in Dres orbit, altered the main spacecraft to an almost polar orbit, then undocked the other mini-probe there.
The mini-probes eschewed main fuel tanks or main engines at all: all they had were a couple of micro-size monoprop tanks and two RCS thrusters on either side for maneuvering. At the top, a mini probe core, communications array, and nuclear power generator. Attached to the sides, the four smallest science instruments. Once I was happy with the orbits, I swung a miniprobe around to retrograde and fired the RCS thrusters. Dres's very minor gravity was no impediment to deorbiting this way and even better, I used the same two RCS thrusters to soft-land the mini-probe on Dres (though it fell over):
Once I had science collected from the mini-probe's instruments, it was time to soft land the main probe, which could not have gone more smoothly. I used the few drops of fuel left in the upper stage to do the deorbit burn, then cut that portion loose and used the probe's main engines for the landing. I barely used any of that fuel at all. Even more amusingly, if you look closely, you can see I landed very close to where the upper stage crashed after I cut it loose! You can see debris from it in the background, the shadow from more debris in the foreground lower right.
All in all, the mission racked up about 350 science or so. I almost felt bad that I didn't plan to return Pathfinder 6 to Kerbin, but this was just a fun mission for a lark. The probe remains on Dres with one of the mini-probes in orbit.
Thanks for the tips, everyone! Next up: I used some of my science to buy... ummm... wheels.