🌙 Lunar Powered Descent: Suicide Burn, Fuel Budget and the Rocket Equation (2D)

Side view of a lander descending to the Moon on a throttleable rocket engine. Change the starting altitude and speed, the dry mass and fuel, the engine thrust and specific impulse, the burn timing margin and the manual throttle, and watch the descent, the braking curve in the speed-altitude plane and the fuel running down. The rocket equation, hover fuel flow, free-fall time and the closed-form constant-thrust burn are checked numerically, with four in-page numerical checks.