Keplerian dynamics

Some tools from the two-body problem.

Bm(rper, Vinf, mu)	Module of B-point vector.
DeltaV_fb(rper, Vinf, mu)	Delta-v obtained during a flyby.
rocket_eq(Isp, mi, mf)	Tsiolkovsky rocket equation.
rocket_eq_mi(Isp, DV, mf)	Tsiolkovsky rocket equation inverse to obtain initial mass.
reqins(Isp, DV, mf)	Tsiolkovsky rocket equation inverse applied to a sequence of delta-v.
lambert(r1, r2, alpha, TOF[, nu_guess])	Solves lambert problem for circular and coplanar orbits.
energy(mu, a)	Computes orbit energy.
velocity_from_energy(mu, energy, r)	Computes velocity in a given orbital position from energy.
velocity_circular_orbit(mu, a)	Computes velocity of a circular orbit.
solve_kepler_equation(n, e, TOF[, E])	Solves kepler equation iteratively
ss_inclination(a[, e])	Calculates critical inclination for a sunsynchronous orbit around Earth.