Reading: Develop the model
Use the correct inward force
An ideal satellite of mass m in a circular orbit of radius r around a central body of mass M requires centripetal net force mv²/r. Under the two-body approximation, gravity supplies it: GMm/r² = mv²/r. For nonzero satellite mass, cancel m and solve v=√(GM/r). Note that G and M appear together as gravitational parameter μ=GM.
How long for an orbit?
Orbital period is circumference divided by speed: T=2πr/v. Substituting circular speed gives T=2π√(r³/μ). Increasing radius lowers circular speed but lengthens the orbital period. Doubling orbital radius increases period by 2^(3/2), or about 2.83, in the ideal two-body model.
Compare an illustrative low Earth orbit
Using Earth's μ≈3.986004418×10¹⁴ m³/s², R≈6.371×10⁶ m, and altitude 400 km, r≈6.771×10⁶ m. Circular speed is around 7.67 km/s and period roughly 92.4 minutes. These are ideal-model estimates and not real-time tracking of any spacecraft.
Do not generalize outside the assumptions
Circular speed formula describes an ideal circular orbit around a dominant central mass. Elliptical speeds vary along the trajectory, actual bodies perturb one another, and atmospheric drag modifies low Earth orbits. The simulator does not model stationkeeping, ascent, maneuver planning, atmospheric entry or orbital debris.