I bought Kerbal Space Program about 4 weeks ago, and now I'm in the process of setting up a Mun base. I know there have been a few KSP AAR's around here lately, but I just couldn't resist adding one of my own! This is using vanilla KSP - no mods, no mechjeb.
It's mid-morning at the Kerbal Space Centre, and my rocket is ready to launch. Today's flight is a dual mission - to deliver a communications array to the newly established Mun base, and to perform a crew rotation on Munlab, currently staffed by Jebediah and Bob Kerman.
The rocket is large and complex. There are 4 stages:
The launch stage
, which lifts the rocket to around 12,000 metres; the orbit stage
, which establishes a low Kerbin orbit and begins the burn towards Mun; the lander
, which completes the burn, establishes munar orbit and lands(this stage also functions as a permanent mun base installation upon landing); and finally the return stage
, which brings the crew back to Kerbin.
Liftoff! The pad supports disengage and the huge rocket stays stable as it slowly climbs. It takes half the first stage's fuel just to reach 100m/s. I throttle the seven engines back to 80% to avoid overheating and excessive acceleration during the second half of the stage's burn.
With the first stage out of fuel, it's time to jettison the empty tanks and fire up the orbit stage. The decouplers explode off and the empty launch stage disintegrates beneath the blast of the engines.
I'm now pointing the rocket at just 30 degrees above the horizon, and waiting for my Apoapsis to reach the magic number: 70,000m - where Kerbin's atmosphere ends. As my horizontal burn approaches orbital velocity, I see the Mun rising, and begin a second burn to turn my circular Kerbin orbit into an elliptical transfer orbit, which will bring me to the Mun's position.
As I decouple the orbit stage and fire up the lander's engines, disaster strikes! The explosion of my stage decouplers blows off the central engine on the lander, leaving me with only 3 of my 4 engines operational. Fortunately, the three outboard engines keep the craft stable, meaning I don't have to immediately abort the mission. I'm concerned about fuel situation though: Now one of my fuel tanks is completely useless, and will be dead weight during the munar landing. I will have to conserve fuel very carefully, and prepare to abort if things go bad.
With the remaining three engines on full thrust, I perform a Hohlmann transfer orbit which takes me right past the Mun on an escape vector. Once I reach the periapsis (yellow marker), I'll do a retrograde burn to enter a circular orbit around the Mun. That'll be in about 8 hours time.
I reach the Mun and establish a circular orbit. I can see the site where I will be landing on the trajectory map - unfortunately, the sun is just about to set there. I really want good visibility for the landing attempt, especially since my fuel situation is critical, so I will have to wait in orbit for 12 hours first.
The sun has finally risen on the landing site, so it's time to start the decent. I burn against the orbit and slightly to the south, as the landing site is south of the equator. Cutting my speed to a few hundred metres per second, I will be decending almost vertically into the crater where the Mun base is located.
I am really beginning to miss that fourth engine on the lander as I approach the surface: even in the Mun's low gravity I am having to apply almost full power to slow myself, and my precious fuel is quickly disappearing. At this point I'm not concerned with precisely nailing the landing site - simply landing in the correct crater will do. I manage to bring the lander from 250m/s down to a hover in just 8km, extend my landing gear, and gently settle down onto the munar surface. I am about 2.4km away from the Mun base, with only 10% of my fuel remaining.
I'm not very far from the base, but my fuel is extremely low. At this short distance I figure if I run out of fuel, I can complete the trip using the return stage's engines, so I might as well give it a shot. I lift off and 'taxi' across to the base at just a few metres altitude, firing the engines in tiny bursts. The lander has a thrust to weight ratio of about 1.5 on Kerbin, so on the Mun I only need to keep the throttle at about 10% to hover. My fuel is looking desperately low as I approach the Mun base, but I can tell I'm going to make it.
Touchdown, and I'm exactly in position! The lander, which is now the base's new communications array, is sitting right next to Munlab, and I can see Munbus nearby as well. I'm pretty pleased to have made it, especially considering the damage to the lander that occurred during stage separation.
It's time to disengage the return pod from the lander and get ready to meet up with Jeb and Bob at Munlab.
The Mun base is already looking much more complete: Muncomms (left) Munlab (centre top) Munbus (right), return pod (centre low).
With the return pod on the surface, Kenzor and Sidrie disembark and start walking over to Munlab. The four Kerbalnauts meet for a briefing on the return trip and the rotation of the lab's crew.
With Kenzor and Sidrie now in command of Munlab, Jeb and Bob join Bill in the return pod. We blast off and enter orbit.
To get back to Kerbin, we need to first exit orbit in the opposite direction to the Mun's travel, so that we will be travelling slowly relative to Kerbin. Then we alter the trajectory to bring us through the top of Kerbin's atmosphere at our periapsis, hopefully using the atmospheric drag to slow the craft down and establish a circular orbit. I estimate that an altitude of 33 km should do the trick.
As we skim the upper edge of the atmosphere, I realize that I've overdone it slightly, and we're bleeding off too much speed. I give the thrusters a few short burst to make sure we don't go into a premature reentry. Bob and Bill find this terrifying... Jeb is of course loving it!
We're now back in a circular orbit, and thankfully it's daytime at the Kerbal Space Centre, which means we can reenter right away. The only challenge is making sure I land nearby, as the Kerbals don't have a great reputation for conducting search and rescue!
Reaching my reentry point, I burn retrograde and try to overshoot the KSC by several kilometres, to take atmospheric drag into account.
Hitting the thicker part of the atmophere, the return pod unfortunately decides that it wants to point nose down, probably due to the aerodynamic shape of the command pod. My plans of landing back on the pad at KSC are undone, but I shouldn't miss it by much anyway. I jettison the command pod and hope for the best.
I'm a kilometre or so short of the KSC by the time I open my parachute. Touchdown will be at a bumpy 7m/s, and from there it's just a short walk back to the Space Centre.
Overall, I'm pleased with the mission outcome. It involved 4 landings, each requiring some precision, and the near disaster early on in the mission added to the challenge. I hope to be adding more modules to the Mun base soon.