Two Worlds, One Tank: a Dawn-Class Mission

Rebuild the mission design that let one spacecraft orbit Vesta and then Ceres.

Every spacecraft before Dawn that visited several bodies flew past them. Dawn stopped: it orbited Vesta for fourteen months, left, and orbited Ceres until its hydrazine ran out. In this assignment you rebuild the design decisions that made that possible — the low-thrust budget with the real plane change, the phasing that fixed when Dawn had to leave Vesta, the spiral down to Ceres on a fraction of the power available at Earth, and the xenon budget, with margin, that a review board would sign.

Ion propulsion and the rocket equationEdelbaum's low-thrust approximationAsteroid ephemerides from orbital elementsPhasing a low-thrust transferSolar-electric power at distancePropellant budgets with margin

Milestones

0/5

Dawn is the only spacecraft to have orbited two bodies beyond the Earth–Moon system. Start where its mission designers started: is there enough propellant? • ELEMENTS holds JPL's osculating elements for Vesta and Ceres (a in AU, angles in degrees). • Write relative_inclination(b1, b2) from i and the node of each orbit. • Write edelbaum(b1, b2): treat both orbits as circular, Δv = sqrt(v0² + v1² − 2 v0 v1 cos(π/2 · Δi)). • Write xenon(m0, dv) at Isp 3,100 s. Dawn weighed about 1,012 kg when it left Vesta.

numpyscipy

The heliocentric leg

Xenon for the whole second leg (Dawn allocated 112 kg)