Devlog 2: Kerbal Gravity Program (KGP)

KGP is a mission planning tool I’m building for KSP players and actual aerospace engineers to map out complex trajectories. It’s loosely based on libraries like Skyfield, Poliastro, and trajectorize. The ultimate goal is to make it easy to plot out massive interplanetary trips, whether you’re trying to reach Jool and Sarnus (with the Outer Planets Mod) or calculating a real-world journey out to Neptune.

What I did today

Today was way more math-heavy than I expected. I spent most of my time building out the core infrastructure:

• The Orbit class to actually handle orbital mechanics.
• The Body class for celestial bodies and barycenters.
• The absolute_position function to figure out the exact coordinates of an object in a nested system, tracking it all the way back to the root central body as the origin.

What I learned

• Planet tracking is wild: The sheer amount of math required to find the exact position of a planet at a specific timestamp is honestly mind-boggling. It took a lot of staring at equations, but once I finally understood the logic, implementing it became a lot smoother.
• The heavy lifters are terrifying: The core system is going to rely on a Lambert solver and an RK4 integrator. I’ll be honest—these algorithms are so intensely complex that it looks like scribbles on paper.

Anyway, here is a small test run of the Python prototype in action:

Devlog 1: Kerbal Gravity Program (KGP)

KGP is a mission planning tool I am building for KSP players and actual aerospace engineers to map out complex trajectories. Loosely based on Skyfield, Poliastro and trajectorize, The goal is to make it easy to plot out massive interplanetary trips, whether you are trying to reach Jool and Sarnus (with the Outer Planets Mod) or calculating a real-world journey out to Neptune.

What I Did Today

1. Mapped out the 4-phase development roadmap

   • Decided to use a mix of C++ for raw execution speed and Python for fast development.
   • Phase 1 (Basic Systems): Building out the underlying math frameworks and foundations.
   • Phase 2 (CLI Interface): Creating simple command-line helper functions.
   • Phase 3 (GUI Interface): Designing a desktop app version with a clean installation setup.
   • Phase 4 (Web Interface): Deploying a browser version so anyone can use it without downloading a thing.
     (Note: Organized it this way to work around the Stardance demo link limits while keeping the scope clear).

2. Coded the Universal Time Converter

   • Wrote the core function that converts calendar dates directly into raw seconds.
   • Made sure it seamlessly handles both Kerbal time standards and real-world J2000 epoch timelines.

What I Learnt

• Numba memory management: I found out that numba (the Python library I’m using to get close to C++ speeds) really struggles when handling pointers and raw memory addresses.

• Python can actually segfault: It actually threw a segmentation fault—which felt crazy to see inside Python code! Because of this, using nb.defered_type() is completely out of the picture for this architecture, so I’ll have to use something like scipy and numpy.

well for your entertainment, here is a screenshot of me trying to figure out why the hell was VS code giving me a problem (i forgot a semicolon on the line before):