How "Kestrel Ops" was made

A satellite mission-control console for a spacecraft that does not exist. One idea, executed honestly: instead of faking telemetry with random noise, a small orbital model actually runs in the browser, and every panel — the ground track, the eclipse timing, the battery — reads from it. The word Simulation sits in the header because that is exactly what it is.

What it demonstrates

That "looks like NASA" does not require deception. The hard, interesting part of a control room is not the dark theme; it is that all the numbers are consistent with each other because they come from the same physics. Change the altitude and the velocity, period, eclipse fraction and power sawtooth all move together, correctly, because none of them is hand-typed.

The techniques, honestly named

• A real orbit, closed-form. Circular orbit at 420 km, 51.6° inclination. Speed is v = √(GM/r) and period is T = 2π√(r³/GM) from Earth's gravitational parameter GM = 3.986×10¹⁴ m³/s² — giving 7.66 km/s and 92.8 min, the real figures for that altitude.
• Ground track from spherical geometry. The sub-satellite latitude and longitude come from the argument of latitude and the inclination; the longitude is then rotated west by Earth's sidereal rate, which is why each pass lands about 23° further west than the last. Plotted on a labelled equirectangular graticule.
• Eclipse by a shadow model. A cylindrical-umbra model with the Sun in the orbit plane puts the satellite in shadow whenever it is within arcsin(R/r) of the anti-solar point — an eclipse fraction of 38.7% here. The ground track and the power chart are shaded from the same test.
• An integrated power balance. The array makes power only in sunlight; a constant load runs always; the battery's state of charge is integrated step by step. The array is deliberately sized so the orbit-averaged energy is roughly neutral, so the battery settles into a shallow sawtooth instead of dying — the same sizing problem a real power engineer solves.
• Ground-station passes. A real station (Malindi, an equatorial downlink site) acquires the satellite whenever the sub-point falls inside its horizon circle, arccos(R/r) ≈ 20° wide. Acquisition and loss of signal are logged with sim timestamps.

Charts are drawn on <canvas> with real axes and units; each carries an aria-label describing what it shows, and the numeric telemetry panel conveys the same values as text. The loop is a single requestAnimationFrame, paused when the tab is hidden; reduced-motion visitors get a paused console they can start with the Play button. devicePixelRatio is capped at 2.

Recreate it