BELT
DAWN AT VESTA AND CERES
The first spacecraft to orbit two worlds beyond Earth.
BEGIN — CHAPTER 01 →Two leftovers from the building of the planets
The rocky planets were assembled from smaller bodies.
Vesta and Ceres took different paths.
A small box with 20-metre wings and a tank of xenon
Dawn weighed 1,217.7 kg at launch.
A Delta II Heavy launched it on 27 September 2007.
11.49 km/s from 425 kg
Dawn changed its speed by 11.49 km/s in total.
The rocket equation says why.
Milestones from the Dawn ion-propulsion papers.
The weight of a sheet of paper, for years
The push of a sheet of paper.
The engine never stops.
92 mN is the most one engine could give.
A protoplanet with a core, and a crater nearly as wide as itself
Dawn mapped Vesta from three orbits.
Rheasilvia is 500 km wide.
Weeks to go down a few hundred kilometres
Dawn spiralled between orbits.
Pick a world and an orbit.
HAMO and LAMO: high- and low-altitude mapping orbits.
A dwarf planet with salt water underneath
On 6 March 2015 Dawn entered orbit around Ceres.
Occator's bright spots are sodium carbonate.
Dawn ran out of hydrazine in 2018.
Dawn is still in orbit.
Same belt, opposite natures
Dawn weighed both worlds.
Gravity on both is weak but not tiny.
Mass from GM and mean diameters.
The first truly interplanetary spaceship
Dawn arrived, stayed, mapped, left, and did it all again somewhere else.