The Space Flight Simulator Gap

Kerbal Space Program 2 is the sequel to the space flight simulation game Kerbal Space Program. Credit: Star Theory and Private Division.

Space has a strange position in modern gaming. Sure, many games are based on science-fiction settings, featuring spaceships blasting each other with lasers. SpaceQ featured Canada’s own Mass Effect series, where players jet from planet to planet in a growing war against ancient alien robots, as only one of countless examples.

Rarity of space flight simulators

Yet games featuring realistic spaceflight are quite rare. There are some, like the long-running Elite series, that do feature realistic momentum and thrust, but gravity is rarely part of the equation. And one of the very first video games, “Spacewar!” for the DEC PDP-1 minicomputer, featured two ships dogfighting in the gravity well of a star. Most, though, don’t really involve anything even resembling celestial and orbital mechanics; often, like in Star Wars, they fly more like planes than like actual rockets.

Games about a recognizable modern space program featuring realistic rocketry and orbital mechanics, though? They are vanishingly rare. There are a few exceptions, like Buzz Aldrin’s Race into Space, the old C64 game Project: Space Station, the Atari’s Space Shuttle: A Journey Into Space and Microsoft’s flight sim spinoff Microsoft Space Simulator. It’s hard to find a balance between overly simplistic mechanics, like those seen in the recent No Man’s Sky, or incredibly dry simulations like in the recent Orbiter.

That’s why it was such a revelation when, in 2012, the “early access” beta for Kerbal Space Program was launched. In KSF, players design and fly spacecraft for a race of small green creatures called “Kerbals.” The Kerbals want to get into space, and are so incredibly keen on spaceflight that they’ve started cobbling together a ramshackle version of a modern space program—one that’s more than a little prone to blowing the enthusiastic little guys up. Your job is to help them get up there, without any more explosions than necessary.

A Kerbal
A Kerbal. Credit: Star Theory and Private Division.

In 2015 the full game was released, and it remains a hit. Players discovered a unique blend of accessibility, comedy and simulation that nobody had seen before.

“Maybe I’ll try going sideways?”

Playing KSF seems both daunting at first, then disarmingly simple. You use an accessible but surprisingly powerful 3D ship designer tool to snap rocket parts together. The pool of parts grows over time as the Kerbals develop their scientific acumen, but the initial parts are incredibly simple: a crew capsule, a few solid and liquid rocket engines, maybe a fuel tank or two, and the all-important landing parachutes. After you finish strapping a capsule to a solid rocket engine and adding a cute, silly-looking green pilot, you can go immediately to the launch pad, and push the spacebar to launch into the sky.

Then, about five seconds after launch, it’s going to go completely haywire and spin completely out of control. Your rocket will plow into the deck, killing your poor Kerbal pilot. You have no idea what happened, or why it didn’t work like the rockets you see on TV, but you can’t stop laughing at the spectacle, even if you feel bad for the little green pilot. Then you restore your game.

That moment when you restore your game, revive the pilot and go back to the drawing board is when Kerbal Space Program really starts. You realize— just as I did — that despite the accessibility, this is a real simulation, and you have a lot to learn. That’s when the “KSP loop” starts, as described by space science educator Scott Manley.

You build another rocket. You add some fins to the rocket, pay a bit more attention to the aerodynamics, and play with the interface and discover the stability assist function. You turn the stability assist on, and the rocket launches and stays stable! It goes up, runs out of fuel, the rocket falls, you deploy the parachute. The parachute can’t handle all the weight. The parachute snaps. The rocket falls. The rocket hits the deck. The rocket explodes. Then you restore your game.

You look at the parts list again, and find the decouplers. You add a decoupler between the pod and the rest of the rocket. You take it out on the launchpad. You press “launch” … and watch as the decoupler fires at the same time as the rocket. Your now-freed booster sails into the sky, never to be seen again, and the pod ends up getting launched sideways at Mach 2 plowing into the ground.

Somehow the pilot’s okay, though, as Kerbals are pretty resilient. You realize that proper staging sequences are important. Then you restore your game.

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So it goes, looping again and again, with you learning more each time. You discover that you want to use a liquid engine because you can control the throttle and it has vectored thrust, but it needs fuel, so you add a huge stack of fuel tanks. Then the rocket’s too tall, and its center of gravity is completely screwed up, so it falls over on the pad.

You add solid rocket boosters to the side, which stabilizes it a bit and adds thrust. Then, after launch, you discover that they lose their fuel long before the central liquid engine does, and there’s too much weight for the central liquid booster to handle. So you learn to add side-mounted decouplers so you can discard the boosters when they’re done and save weight. It’s good, but it’s not enough. You barely break out of the atmosphere.

Then you have a “eureka” moment, and try to snap a second liquid engine in between two of the fuel tanks, and the game automatically separates them and puts faring around the upper engine. Now you can make a high-powered ascent stage and an upper atmosphere stage with a smaller engine that’s better in near-vacuum. It’s just like a real rocket! … except that you forgot to add a decoupler again, and firing the second engine just makes the whole thing explode. Another restore.

Build your own rocket, but beware, you have to follow all the real world rules, ie. gravity etc., if you plan to get it into space
Build your own rocket, but beware, you have to follow all the real world rules, ie. gravity etc., if you plan to get it into space. Credit: Star Theory and Private Division.

Finally, you break free of the atmosphere, but get frustrated that all you’re doing is going up, then coming back down again. You open up a map that shows your trajectory, and eventually think “okay, up doesn’t work. Maybe I’ll try going sideways?” You point your ship parallel to the ground, hit the burners, and watch the arc grow on the map; more slowly at first, but faster and faster as you get close to the point marked “apoapsis.” Eventually, you’re going “sideways” quickly enough that your trajectory changes from an arc into a circle.

You threw yourself at Kerbal and missed. You’re in orbit now.

By this point, it’s 3AM. You’re tired, bleary-eyed, but satisfied that your little green friend is safely out in space, boggling at the sight of the planet. And, by this point, if you’re like many Kerbal players, you just discovered more about rocketry and orbital mechanics in one day than you’d probably learned in your entire life. You aren’t tired anymore. You’re exultant. Next stop: the moon!

(Once you figure out how to get down. Maybe you could try going sideways in the other direction?)

Expert-Level Kerbal

Of course, most SpaceQ readers will have a pretty solid sense of how orbits work, how launches work, the difference between parallel and serial staging, how to execute a Hohmann transfer orbit, and how to land on an airless body like the Moon. Even if you don’t, there’s an excellent tutorial and training system that runs you through exactly how to light that candle and get out into the black.

The brilliance of KSF is that no matter your level of expertise, it’ll challenge you. If you know how to get into orbit, it’ll challenge you to get to the moon. If you know how to get to the moon, it’ll challenge you to get to Mars. Want to build probes, satellites, and un-kerballed missions? There are parts for that in the game’s “tech tree,” which slowly opens up as a reward for successful flights, scientific experiments, and crew observations.

Want to build a space plane? There’s a whole research tree for those. Want to do some EVA? So do the Kerbals. Want to mine asteroids, land on other planets,and build planetary bases and space stations? Get at it. Looking to do science? Each planet (including Kerbal itself) has a variety of different biomes to explore and study. You can even build your very own Discovery rover to roll around Mars, or Europa, or Pluto, or even Venus if you can pull it off..

Each of these things will challenge all but the most expert players in ways that they may not have anticipated. Doing science means figuring out how to get the scientific instruments where they need to be, doing the test, and getting the data back home. Building a station means understanding orbit-matching and executing intricate orbital docking maneuvers. And as for landing on faraway moons and planets? Any NASA technician could talk your ear off about how involved that is, let alone setting up a permanent presence there.

And, just as with the early getting-to-orbit scenario described above, players at every stage of expertise will be engaged in that “KSP feedback loop.” No matter how complex it gets, the loop remains: build a rocket, fly the rocket, see the problems, fix the problems, and try again.

It’s profoundly engaging.

Kerbal Space Players

Like many popular PC games, Kerbal Space Program has a thriving “mod” (game modification) community. Thanks to the game having comparatively accessible models, game engine components and physics data, modders have been altering the game since its early beta days, with the active support and encouragement of KSF’s developers.

One mod called “Kerbal Engineer” provides detailed information on your orbital periapsis/apoapsis, speed, delta-v, and specific impulse for your particular craft, even while you’re building it. Another mod named kOS (kerbal OS) lets players write flight control code using a powerful interpreted language named “kerboscript”. Still another, “Telemachus,” lets you use KSP to turn your office or living room into a full Mission Control setup.

In fact, modders have often added features that would ultimately be incorporated into the broader game, like the “MechJeb” autopilot mod (named after the starting Kerbal pilot Jebediah Kerman) that would ultimately inspire KSF’s in-game guidance systems.

While the game has incorporated a wide variety of new and updated parts, modders are also adding parts of their own. Some of the parts are intended to add new gameplay experiences, like the “KSP Interstellar” mod that adds futuristic technologies like fusion engines, plasma drives, molten salt reactors, and antimatter drives. Many others look to the past, though, adding both American and Soviet launch systems to KSP.

YouTube and Reddit and other online communities are stuffed with videos showing off people’s bizarre and inventive rocket creations. A quick scan can show you single-launch-to-Mars rockets with dozens of boosters weighing thousands of tons, elaborate multi-part stories about interplanetary colony ships, gigantic stacks of decouplers used to launch a poor Kerbonaut into orbit at about 15 Gs or so, single-stage-to-orbit spaceplanes that land on the Moon, and (for some reason) the giant robot from Pacific Rim.

While one might assume these are just enthusiastic amateurs; but people in the real-world space sector have also embraced KSP as an accessible introduction to their work. Scott Manley has a great early video featuring former NASA astronaut Ed Lu building and flying his own KSP rocket. Ars Technica has another video featuring NASA astronaut Scott Kelly where a KSP simulation of a shuttle launch is used to teach viewers about Max-Q, the pilot’s role in Shuttle launches, and orbital dynamics. And Buzzfeed has a great video with Mars Rover Engineer Timothy Szwarc building a Mars rover, building a rocket to carry it, launching it, flying it, landing it, and taking samples.

That may be why space agencies have embraced Kerbal as well. For those looking for something a bit more rooted in the real world, players can look to KSF’s collaboration with the European Space Agency. KSF’s free “Shared Horizons” update includes the stages, engines and systems of Europe’s Ariane 5 launch vehicle, so that KSF players can directly replicate the real-world rockets. It also includes two famous European missions: a scenario based on the BepiColombo joint European-Japanese mission to mercury, and a KSF version of the celebrated “Rosetta” mission to the comet 67P/Churyumov–Gerasimenko. There’s also a version of NASA’s Asteroid Redirect Mission in the game.

KSP 2: Interstellar travel, one nuclear bomb at a time

Measuring from the start of Beta, KSP has been around for nearly 9 years, and it’s no surprise that there’s a demand for a refresh and revamp. So, about a year ago on August 19 2019, developers Star Theory Games announced that they’d be developing Kerbal Space Program 2.

It’ll have updated graphics, of course, and the developers promise better onboarding for new players. The cinematic trailer reveals the real focus of KSF 2: interstellar travel. The KSF2 team’s promotional material promises thatKSF2’s “next-gen tech, colonies, and systematic resource gathering” will eventually lead to interstellar travel to extrasolar celestial bodies, including ringed super-Earths with heavy gravity, binary star systems, and many more. They also promise full multiplayer support—something that the community has called for for a while—and better modding support.

(As a side note, the trailer itself is a tribute to an early KSF fan trailer, showing the ongoing relationship between the developers and their community.)

That said, these are early days, and there have been challenges. In particular, there was a controversy earlier this year when development shifted from Star Theory Games to an internal team at KSF publisher Take Two Interactive. Take Two attempted (according to reports) to “poach” the developers at Star Theory after cancelling the contract with the external studio.

About a third of the employees moved to Take Two’s new team — eventually called Intercept Games — and between the loss of talent, the loss of the Kerbal contract, and the COVID-19 crisis, Star Theory was forced to shutter its doors shortly afterwards. This may have contributed to the significant delay in KSF2’s release date from 2020 to late 2021. But production grinds on.

One of the most intriguing new technologies in KSF2 is a functional Project Orion drive. Project Orion — actually proposed but never built in real life — ejects small nuclear bombs from the back of a rocket, which detonate against a “pusher plate” that propels the craft forward. The technology never took off in real life for obvious reasons — nobody wants to transport tons of volatile nuclear material from earth into the sky — but it makes a lot more sense as a “what if” scenario with the with the freewheeling Kerbals, and the KSF2 team is excited at the prospect of bringing Project Orion to life, along with other speculative technologies like metallic hydrogen engines.

Will they blow up? Of course they’ll blow up. Everything blows up in Kerbal Space Program. That’s why KSP 2’s team are busily modelling more realistic explosions. But players will do what they’ve been doing for the past eight years: they’ll restore their game, get back to the rocket designer, get back to the pad … and try again.

About Craig Bamford

Craig started writing for SpaceQ in 2017 as their space culture reporter, shifting to Canadian business and startup reporting in 2019. He is a member of the Canadian Association of Journalists, and has a Master's Degree in International Security from the Norman Paterson School of International Affairs. He lives in Toronto.

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