cantab

The nuclear engine is the obvious choice. SO good for interplanetary travel. Its partner depends on what you want to do. If you like larger landers, consider large control for the Mk2 can. If you like not killing kerbals, the same node gives you the Launch Escape System. If you like lightweight probes, I'd consider ions and large electrics, and dropping the nuclear engines for now. If you like lightweight Kerballed missions, go for field science for the external seat. If you fancy going for a drive, the same node gives the wheels. If you're really fed up of losing control of probes because you run out of electricity, get Specialized electrics for the RTG and wait for the LV-N. And if you just want a grab bag of parts to play with, pick the metalworks. Finally, I wouldn't overlook that aerodynamics track. Even if you don't care for planes now, it ends with the Aerospike, which you'll want for a (returning) Eve lander.

If your probe had a science instrument, try hitting a different biome with your second one. As far as mods go, it's worth getting one that shows your surface/"radar" altitude. VOID will do this in a head-up-display and is my pick, or Engineer Redux gives the info in the Surface window. MechJeb'll probably do it too. Whichever mod you use, it's so much easier than trying to judge things from shadows (which might not even show if you have graphics detail down).

My guess is you aren't clicking the right tank. As for the symbols, a green arrow means the resource can be drained from the tank. A red crossed circle means the resource will not be drained from the tank, it's effectively disabled. Click the symbol to swap between them. This isn't often needed for fuel and oxidizer, but it's helpful to stop monopropellant tanks in landers getting drained.

Try being cautious with the gravity turn. Make it slowly keeping your heading on or near the edge of the prograde circle, instead of beaning it over to 45 degrees. If that doesn't work, try also making it later than normal, reducing the drag forces.

Well if you're going to just say "pitch down 20 degrees", you may as well be telling someone else to play the game for you. Or using MechJeb, which amounts to the same thing.*ducks*

I meant non-trivial in terms of choosing and implementing the solution to the problem. Indeed with a well-designed system it can be easy to use.

The challenge is how to deal with people getting out of sync. Let's say I send a ship to Duna and timewarp until it gets there, but then you send a ship to Duna that arrives later in real time but earlier in the game because you used a quicker transfer. The KMP mod has a way of dealing with, but it's certainly non-trivial.

I'm not sure how you'd get somewhere without making a Hohmann transfer (aside from a deliberate bi-elliptic).

Keyboard. And not mouse, that's just for moving the camera and opening the menus. If I wanted to get serious about planes I might give a controller a try, but I think KSP doesn't have full controller support on Linux, so I don't know if I'd be able to get the analogue sticks working. For rockets the keyboard does just fine.

You don't need to land the entire interstellar ship...

You can still set a station around L3, 4, or 5, with the same orbital period as Kerbin. It's just there's nothing special about those points in KSP, you can put a station anywhere around Kerbin's orbit. And you won't get the low energy transfers and stuff.

Yes, semi-deployed parachutes give increased drag. It's not much but they will help bleed off your speed. Edit: The drag coefficient of a semi-deployed chute is 1, compared to normal parts that have 0.2, but fully-deployed chutes have 500. For the drogue chute though the values are 4 and 170.

There've been stock Jool "landers". That takes around 30 km/s of delta-V to get from datum back into orbit, with enough thrust all the way, and that's not even counting what it took to get over to Jool in the first place. OK, by that point you're returning a probe core or a lawn chair, but going back is going back.Relative stellar velocities is a fair point, in real life that would significantly up the delta-V requirements, but I think ignoring them for KSP wouldn't be unreasonable. Actually thinking I might have a crack at a simulated interstellar mission now. Just establish an escape trajectory, then hyperedit onto an entry trajectory to simulate entering a new star system. (If I really wanted to be flashy I could copy the craft into a separate Alternis Kerbol save/install.)

I've used girders for landing legs when I was doing landings with very early parts. They work, but they're not ideal, being both heavy and not giving as good grip on touching down. As much as anything else, technique is important. If you can land with minimum horizontal speed on flat ground, if you can react quickly and use the command pod/reaction wheel torque to keep the ship upright, you can land fairly top-heavy ships safely. Landing on your engines is perfectly possible if you're careful. If you can't do these things, well I managed to do this: https://flic.kr/p/nq5kAW

Done this mistake so many times. Controlling from a point reversed 180 usually gives itself away by the rapidly increasing burn time, but when I had control from a point 90 degrees out I first thought my engines were faulty. Nearly messed up a mission because of that, wasted a load of fuel.

On the other hand, from my experience rendezvousing with asteroids in solar orbit, 200 km is an OK distance from which to make a final approach (ie lining up your relative prograde vector with the direction the target is in so you're heading straight at it). Your overall orbit is so much bigger that in comparison a couple of hundred km is nearby.Admiteddly all my asteroid rendezvous have been with rocks scheduled to enter Kerbin's SOI, where you can use the trick of heading out the way the rock will come in to get a good intercept. Still, though trickier than hitting a planetary SOI, rendezvousing with a station in solar orbit shouldn't be that difficult as long as you have enough delta-V.

Well, .23.5 did introduce a new science experiment: asteroid surface samples. And they're subject to situation like anything else, so you'll get new results when you make an SOI change. The conclusion is simple: grab a rock and take it on a tour of the system!

This needs some scoring to make a proper challenge. Anyway, I normally have render quality on minimum which means no shadows at all. VOID though gives me a radar altimeter in the HUD to make up for it, and I caught this close shave on approach to landing. I really thought I was going to hit the hill, but passed just over it. 186 m altitude at 157 m/s. CLOSE! by cantab314, on Flickr I mucked up the landing after, but that's by the by. Though I suppose it's not technically a valid entry since I was suborbital. Of course it's nigh-impossible to screenshot the absolute lowest approach. Anybody know a mod that can record minimum altitude achieved? Thatt would really help challenges like this.

Never lost one on re-entry, though I've been made nervous when I've come in fast and steep. I can see how in older versions the drag forces might be able to break a ship even in stock, but would be surprised if it occured in .23.5 with its lolstrong joints.

The side reactions do produce neutron radiation, and while it's not much when it comes to energy losses it's more than "occasional" and probably enough to be hazardous. The X-rays are also hazardous. In any case, shielding the reactor is the easy bit. Heck, achieving net energy gain is the easy bit. Convincing the public the reactor poses no threat to them, that's the hard bit. Considering how radiation-phobic the general public are nowadays, I can't see your idea of fusion power stations being widely located in urban areas happening any time soon. Basically, I don't highly rate the intelligence or the rationality of the general public on things like this.

Considering that fusion reactors give off radiation, you won't be seeing one in each city neighbourhood, there'll be too many protesting residents.Meanwhile long-distance power transmission isn't that lossy. HVDC gives losses of just 3% per thousand km, with improvements continuing to be made.

Some parts are more lag-inducing. From memory docked docking ports have a bigger penalty than regular parts, for example. The Engineer calculations, used to display vessel delta-V in Engineer and VOID, also aggravate lag, so if your ship has that on and running there's your explanation.

A couple of less obvious options: solar impact and solar escape. Solar impact especially requires a load of delta-V, though the requirement can be reduced a fair amount with a good choice of trajectory. (Ie you can do better than a simple direct Kerbin-Sun transfer).

Looking at that chart in the OP, yeah, it's way overcomplicated I think. So far kethane's the only ISRU mod I've used, and I think it has broadly the right idea. A small number of primary resources (just one in kethane ofc), and a one-step conversion from resource(s) to product. It's still not trivial - there's work involved in making a good kethane miner - but the simplicity keeps it in the realm of being a way to support your missions, and not a string of interplanetary fetch quests that dominates your projects. Kethane also encourages the player to do some things they otherwise might not do, which I think is a good thing for any ISRU system to do. Start by scanning, well you're going to want an inclined orbit, not the "default" equatorial you'd probably pick. Then once you've found a deposit you need to land on it, you can't just set down anywhere. (Biome science also enocurages the player to do both of these). Finally, you presumably want your fuel up in orbit, so you start designing heavy landers that are up to the task, and figuring out how to dock vessels on the surface to transfer the fuel about. And yes kethane's a bit waity on the scanning, but I'm assuming that's just because Majiir hasn't got round to coding inactive vessel scanning yet. There's no reason for ISRU to be any more waity than regular space travel. Set it going, timewarp, come back later. As for whether it's needed in stock, well I'd say no. In a sense an ISRU system starts to turn KSP into a different game, less simple space exploration and more strategy game style infrastructure development. A good ISRU system would add to the game, but if Squad put in everything that could add to the game we'd have a bloated mess.

Possibly none, or one with zero or near-zero gravitating mass. ("Near zero" would keep the physics engine happy.) I think that would be a reasonable approximation, once you're far enough out that the gravity of the stars around you is tiny and you're basically going to coast in a straight line.