Community-built physics experiments and study materials — run an experiment live and fork it into your own studio, or read a guide someone wrote.
Seven tonnes falling at 6 m/s with fourteen metres to go, onto a shock-absorbing deck, in a sixth of Earth's gravity. Nothing scripts this landing. A node graph on the lander reads its own height and velocity every step, decides a throttle, and pushes — that graph IS the autopilot, and every number in it is a slider. Turn the gain down and watch it arrive too fast. Lengthen the contact probe and watch it cut the engine too early. Sideways is your job.
Falcon 9's published numbers — a 25.6 t first stage with 395.7 t of propellant and 7.6 MN of thrust, a 3.9 t upper stage with 92.7 t behind a 981 kN vacuum engine, a 15.6 t satellite — in kilometres and tonnes. Gravity is Newton's law from Earth's centre 6371 km down; air thins with the real 8.5 km scale height, so drag, max-Q and vacuum thrust share one formula. Propellant leaves the mass every step. Guidance is a controller you can take apart: kick, gravity turn, climb law, cut-off.
