Jan 282015

Just before Christmas I had a couple of days off work and planned to give Elite a proper play, but then something happened: a friend very kindly bought me a copy of Kerbal Space Program. I knew of the game and I’d always been curious, but I assumed I would quickly get bored of a predominantly sandbox experience. Apparently I was wrong – I booted it up one morning and spent the next three days solid engrossed in orbital mechanics, staging, lander design and “delta-v”.

The game involves building rockets and space planes from a huge variety of components and launching them into space to explore the solar system (different to but based on our solar system, which I guess stops people nitpicking about accuracy), while using reasonably realistic physics. As such, it was humbling as a self-confessed science/space nerd that it took an hour of failures and a tutorial before I managed to get a rocket into orbit. It’s refreshing to play a game that pays so little attention to traditional ‘gaming’ experience and relies so much on a knowledge of physics.


A brave Kerbal on his way to the moon

There are three different game modes – sandbox mode where everything is available, “Science sandbox” where new parts are unlocked by doing new things and using scientific instruments, and a full career mode which also adds money earned through contracts. I was warned that the career mode was really hard, so I went with Science mode. This lowers the learning curve of Sandbox mode by introducing new components slowly, while removing the stress of money and crew management. The game is still in Beta but when it’s done I’ll have a stab at Career mode now I vaguely know what I’m doing.


This little guy can’t get home. I’ve reclassified him as Moon Base 1

I was struck by the familiarity of my progression during the first few hours compared to the real space programmes, and the real sense of accomplishment that I’d not felt in a game for years:

  1. Fire a rocket up into the air. Heh, this is cool.
  2. Fire a rocket up into the air and parachute the capsule back home. First successful mission.
  3. Blast well into space before splashing down in the ocean. Sub-orbital space flight!
  4. Making it into orbit (eventually) and safely de-orbiting. Ooh, reentry looks cool.
  5. Getting into orbit, firing off towards the moon, slingshotting round the back and getting back home again. Landing there looks tricky!
  6. Getting to the moon, going into obit and landing on the surface in one piece. Having no fuel left for the return journey (real-life thankfully skipped this stage).
  7. Landing on the moon, grabbing surface samples, getting back into space and making it back in one piece for the first time. A real accomplishment!

About to ditch the last stage and deploy the parachutes for splashdown

Each stage presents new challenges and physics concepts to master. Getting into space requires staging (jettisoning empty fuel tanks and engines to make the rocket lighter). Obtaining a circular orbit needs an understanding of the apoapsis and periapsis orbital nodes (farthest and nearest points) and how burning at one side of the orbit only affects the other side. And then you can worry about orbital transfers to get to other moons and planets.


Get used to the view, son, you’re stuck on Eve for the forseeable future…

Thankfully the game provides a great maneuver planning tool. The current orbits of all bodies and ships are shown, and you can add planned maneuver nodes along the path. Drag the node in each of the six directions (prograde and retrograde, normal and anti-normal, radial and anti-radial) and the predicted path updates, including closest approaches to other bodies and ‘encounters’ (getting within their gravitational sphere of influence). While I’m sure NASA use complicated maths to plan their paths, in this game dragging nodes around until you hit on something useful also works while you’re getting the hang of what each direction does to your orbit. Then you just follow the directions on your control panel to carry out the planned burn.


The aerodynamic model is very simple, otherwise this rover and sky crane would never get off the ground

 After that the sky is, indeed, the limit. I’ve got “small colonies” (read: failed return missions) on Eve (Venus) and Duna (Mars), and used a sky crane to drop a small rover on the moon. The other planets require even more powerful rockets to reach, and as we speak there are probes scouting the outer planets for my future (probably suicide) missions…

And finally, for the truly brave, there is the small matter of orbital rendezvous and docking. Why get just one spacecraft where you want it to go when you can get two in the same place, at the same speed, at the same time? Building substantial space stations requires launching them in multiple sections, and this is my next project. My first and only successful docking took an hour, but it must get easier. I mean, it’s complicated, but it’s not rocket science.

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