What small mistakes did you make that ruined your mission?

[Xaver]

Forget a antenna for base/station contracts.

[ToothyTurtle]

I left Jeb with SAS on when doing a early rescue mission. With no RCS I had to make rendezvous manoeuvres with just a LVT909. It almost ruined a two Kerbal rescue mission costing 60k.

I don't know how, but I managed it.

[Black Dog]

Adding some final improvements after a failed launch, then fly halfway across the solar system just to find out my paying tourists are still sitting in the KSC waiting room...

Forgetting one fuel line out of 30 or so and finding out my rocket gets unsteerable in the final landing approach because of asymetries in the mass...

[Boots]

I misplaced the fuel lines on my 2nd Mun mission, rendering the lander useless. I discovered this halfway down to the surface of the Mun. Thank god for F5.

I did exactly that. Had to send a second identical lander, but with repaired fuel lines and a probe core, to bring Val back from Mun.

[Rolanvorxariat]

On a Jool mission, I was supposed to first got to Tylo and detach the Tylo lander, then go to Vall, but I went to Vall first and accidentally detached the top probe part of the Tylo Lander, thinking it was the Vall lander, before I found my reference sheet and realized I screwed up, and I had already quicksaved. I will not land on Tylo today.

[cybersol]

I have a small probe module that essentially just has an antenna, and another that just has solar panels. These are tiny and can fly to the site and dock with the other mission to rescue it. I've used this on multiple occasions to fix a PEBKAC error, and it works flawlessly unless I arrive on site to discover that I also forgot the docking ports

[Netskimmer]

I landed Bob on Minmus and was clicking on all my science bits (forgot to add them to action groups) and couldn't quite get to one shoved in the back of a materials bay. Tried to zoom in closer by holding shift and scrolling the mouse wheel, fired up the engines and sent the lander into a mountain side.

Same mission, after restoring a save. Bob was bouncing around with his EVA pack trying to get back in the ship on the dark side of minmus and snagged something momentarily. I did think anything of it since it was hard to see. After getting him back into orbit I saved and sent him back home only to realize I was dead-stick when I came out of time-warp near Kerbin and Bob had died. He snagged the solar array and broke it off, ran out of power and thus life-support (I'm using TAC mod). . He will be missed.

[joekidd1992]

I put drogue chutes on my capsule and of course it crashed.

[Tourist]

Many people have already mentioned it, but the old forgetting to install solar panels on a probe. For bonus points, its infuriating cousin, remembering the panels but forgetting to deploy them.

My other "favourite" is more of a category of mistake.... what I like to call 'staging mishaps.' Parachutes deployed in the very first stage, completely full and firing rockets being jettisoned early (often overtaking and colliding with the vessel), due to over zealous space bar mashing.

[Boots]

Brand new one for me yesterday. Built a tiny Ion probe with two Gigantors for power. Got it into an encounter trajectory, set up a capture maneuver node, then before switching to another ship, did some "high over the sun" science and hit transmit. SAS disengaged and the transmission stopped - terminal dead battery.

Turned out I had laid out the solar panels along the ecliptic plane, so they were blocking themselves. Took a quarter of an orbit to get power back, by which time I'd missed the insertion burn.

[BurningLegion]

Forgot decouplers for nine Mainsail boosters on my Moho mission.

Result: Spacegoing portion of a 2200T launch vehicle dragged back to Kerbin under the weight of the empty fuel tanks it couldn't discard, shedding solar panels during re-entry, frantically firing the upper stages to slow descent and save the life of the one crewmember. Again due to decouplers, that didn't wind up slowing the ship down. Just releasing seven uncontrollable explosive missiles flying at maximum thrust, three of which were nuclear powered.

*Assumes Shatner pose* "DECOOOOUUUUPLLLEEERRSSS!"

Crew survived, though. Will modify and try again.

[Wanderfound]

The last one?

I had a "rescue Kerbal from Mun" contract to do. So, i sent up a two-seater Munlander with a scientist and probe core on board, collected goo/SciJr/thermometer/barometer/crew reports from high and low Munar orbit as well as a couple of landed biomes, then hopped over to our stranded Kerbal once the fuel ran low.

I decouple the radial tanks and lander legs as we launch back towards Kerbin, and set up a single-burn return (i.e. no Munar orbit). Then, halfway back to Kerbin, the "electricity running low" warning comes up. So, I go to unlock the reserve batteries and aim the solar at the sun....when I realise that the solar panels were all mounted on the radial tanks, now left behind on the surface of the Mun.

Although the only thing left for our Kerbals to do was to trigger the decouplers and parachutes (they were already set for a 20km Kerbin periapsis), they never get the chance. Thanks to TAC-Life Support, they were both dead of oxygen toxicity before they made it back to Kerbin, and I get to watch their corpses plus about a thousand science points burn up on reentry.

In hindsight, I should have left the reserve batteries locked off. The Kerbals were dead anyway, and at least with a bit of power I could have used the probe core to save the science. That seemed a touch too ruthless at the time, though.

[Wiseman]

Just realized my Tylo lander doesn't have a ladder.

[Wanderfound]

Just realized my Tylo lander doesn't have a ladder.

Just land it on its side, you'll be fine.

[Goomblah]

Hitting Z instead of X.

I have made several missions much harder and even lost a few because I accidentally went full throttle instead of cutting engines...

[troyfawkes]

Thought Duna's atmosphere meant I could use air breathing engines. That was actually extremely frustrating since it was in a hard core realism game and took so much effort..

[GoSlash27]

Most recent "D'oh moment":

Early career rescue-the-kerbal contract mission with ox-stat panels. I had done a correction burn to intercept and time accelerated without realigning my ship. When I came out of warp... rescue ship was flatlined with the panels pointed away from the sun.

I had to wait several days for the ship to randomly drift back into alignment to restore power and of course by that time the intercept was blown.

Luckily, I had enough fuel to redo the rendezvous and still make deorbit.

Best,

-Slashy

[Galileo Kerbonaut]

Batteries... 'nough said

[herbal space program]

On my first successful Tylo landing, with contracts for tylo flag-planting and surface samples, I failed to notice until it was too late that I had the symmetry on 4 instead of 2 when I placed the landing lights. When I went to disembark, I saw that the result was a mK1 Illuminator coming straight out of the middle of my ladder. There was no way to go around it and no way to jump over it either. Oopsie!

- - - Updated - - -

Batteries... 'nough said

Early in my current 1.0 hard career game I ran my first Munar orbital mission completely out of juice by running it in physics time wrap with the thermometer display toggled on. I had no control authority but the engine gimbal and an LV909 engine that didn't generate any power. I was able to get it back to LKO, but despite many f9s I could never maintain control authority long enough with the tiny bit of fuel I had left to keep from turning nose-first and burning up. That was in 1.00 though. I think the aero might be a tad more forgiving now.

[Mighty1]

Early career to Minmus. Only bateries with no solar and LV-909 to generate power. Guess what: the 909 doesn't have an alternator. The end result was a roasted kerbal.

[KerbMav]

Putting a decoupler between a girder structure and a lower stage instead of between the girders and the engine of the next stage ... (managed to burn the engine free)

Attaching supplies containers (USI LS) to a wide landing stage for a high vessel and leave it behind on Minmus ... (could not let 12 kerbonauts die because of my stupidity, so praid and did service to the god of editing)

[heng]

Left SAS on during reentry... ditched the stage with the batteries/solar panels... by the time i was slow enough to deploy the chutes i was out of power...

that's when i found out kerbals can survive splashdowns of >40m/s.

all the science lost, though. so a fail in my book.

honorable mention:

touchdown on a slope... hatch faced down... EVA resulted in an instant splat and a dead kerbal poor Duddin.

[Cocox]

1. Activating decoupler by mistake.

2. Activating decoupler by mistake.

3. Forgot to fit RCS thursters.

4. Forgot antenna..

[ArchGaden]

On my latest Duna mission, I had 4 vessels sent in. A science station, a lander, 2 ISRU miners. One of the miners was designed to land on Ike to mine and lift off to refuel vessels orbiting Ike or Duna. The other was built lighter with airbrakes and parachutes to aid with landing on Duna. Its purpose was to refuel the lander on the surface. The thing was... I made the Duna miner a little too light. I forget to add a drill entirely.

Fortunately, I drastically overbuilt the Ike miner. I gave it those giant heavy rover wheels, even though it didn't need wheels at all. It was actually a design I use on my Mun and Minmus bases. It came with about 2.8k d/v (when ore is empty), which is plenty to land on Duna without parachutes. I was able to support the Duna lander with that to get on with the science and get my kerbals back up to the station. The station itself needed refueling before it could return to Kerbin though. To do that, I had to launch the Duna miner back to low orbit (dumping ore first), give it fuel from my other vessels, and fly it over to Ike for mining operations. It didn't quite ruin the mission entirely, thanks to a silly overbuilt mining rig, but part of the overall mission goal was to establish infrastructure for future missions, and only half of that is functional. I'll have to send a replacement miner for Duna surface.

[Findthepin1]

I built a Duna colony pack in LKO. It had a rover and two laboratories and a 16-kerbal Hab. Nothing had parachutes and I had no way of landing it.