I’ve recently joined a terrific Facebook group, comprised of players and fans of Kerbal Space Program. It’s an active group, with many posts per day about the game, what people are doing in the game, and space-related topics in general. It a great source of information, advice, encouragement, and, for me, motivation.
I’m currently on a long-term project I’ve named “Land Something on Everything”. I hope to make a landing (successfully, perhaps) on every body in the Kerbol system. Obviously, I can’t land on Kerbol (the sun) or on Jool (the gas giant). Those I’ll make a close orbit and call it achieved.
To make things easier on myself, I’m making each target a one-way mission, with a robotic probe. I’m setting each target as a separate saved game – “Mission Duna”, “Mission Minmus”, and so on – so I can use the successes as the basis of future missions – round-trips with kerbals aboard, maybe.
The idea for the project began when I sent a probe around the sun, to see how close I could get. Once I achieved that, I thought it should be easy to get to Moho, the closest planet to the sun, and the analog of Mercury. It wasn’t as easy as I thought it would be, but after a few failures, I landed a probe on Moho. (The probe ran out of fuel a few meters above the planet’s surface, but it landed without destruction.) So, I got the idea to keep going and land on everything.
When I joined the Facebook group, I had probes on everything except Dres (the analog of Ceres), Jool (the analog of Jupiter) and its five moons, and Eeloo (the analog of Pluto).
I am, of course, using MechJeb in my project. And, of course, MechJeb can’t do everything, so it’s there only to assist me.
I couldn’t tell MechJeb to give me an orbit around Kerbol, since, really, everything already orbits around the sun, so, even though I’d equipped the probe with MechJeb, I did it all myself.
A curious thing happened when I tried to land on Gilly, the moon of Eve (the analog of Venus). MechJeb would send the probe down to Gilly’s surface, but end up with the probe hovering a hundred meters or so above the ground. After restoring the last save a few times, and getting the same result, I guessed that Gilly’s extremely low gravity was confusing Mechjeb. So, the next time the probe started hovering, I switched off MechJeb. The probe dropped until almost to the ground, and then I switched MechJeb back on, and had a successful landing on Gilly. (I still don’t trust my own landing skills.)
The landing on Eve was successful, even though the planet’s thick atmosphere caused one of the probe’s maneuver jets to overheat and explode.
Rarely does MechJeb get me from Kerbin’s orbit to an encounter with another planet, even when I adjust for a planet’s inclination. I’m not sure why. It doesn’t really matter, though. Once it gets me close enough, I can get that encounter by adding my own maneuver node. Like I say, even with MechJeb, I still have to know what I’m doing.
Kerbin (the home planet of the kerbals) was the only landing in the project with a kerballed capsule. I counted a successful re-entry from obit for the project. (I have landed kerbals on Mun, and returned them home, but counted a probe for the project.)
Yesterday, I made my landing on Dres. I really had my doubts, before I started, that I’d ever make it. Dres is a dwarf planet, it’s far away from Kerbin, and on an eccentric and inclined orbit. My first attempt was unsuccessful, but much better than I’d imagined it would be. The rocket got within Dres’ sphere of influence, and ran out of fuel before I could create an orbit.
I left the first rocket out there in space, on an escape trajectory from Dres, and set to work on the next rocket. I kept the design of the first lander probe, and re-designed the rocket from scratch.
After much experimentation, and a whole lot of failure, I hit upon a successful rocket design. It was, in a way, too successful. I achieved a 70 kilometer orbit around Dres with the lander probe attached to the final rocket stage – seven fuel tanks, each more than half-full, attached to an atomic LV-N rocket motor. If I’d attached docking ports, I might have been able to bring the probe back home to Kerbin.
And, of course, the probe landed safely on Dres.
I’m thinking I may try that same rocket design for Jool. The thing I’m wondering, though: Should I try it with six probes attached (one for each probe, plus the orbit around Jool), or make it easier with several launches?