Cassini’s nominal mission was a four-year orbital tour of the Saturn system. Its objectives were to study Saturn’s atmosphere, the atmosphere and surface of Titan, the smaller icy satellites, the rings, and the structure and physical dynamics of the magnetosphere.

And while Cassini flew on, Huygens — dormant, unpowered, a mere ten feet across, spinning slowly for stability — fell directly towards the burnt-orange face of Titan.

It was November 6, 2004.

…It would be a second-generation star.

It formed from a spinning cloud, of primordial hydrogen and helium, polluted by silicon, carbon and oxygen: rock and snow, manufactured by the first stars, the oldest in the Universe.

The cloud was a hundred times the width of the Solar System, to which it would give birth.

The cloud collapsed, and spun faster. It heated up. At last, the cloud became unstable, and broke up into successively smaller fragments.

It shrank. The cloud became opaque, and the heat it generated as it collapsed could no longer escape.

The core imploded suddenly.

The collapse made the core, a protostar, shine brilliantly, ten thousand times as bright as the sun that would shine on mankind.

Eventually the core was so hot that hydrogen nuclei began to fuse to helium. The thermonuclear energy generated balanced the inward gravitational force. The protostar stopped contracting.

It was a star. The sun.

The remaining nebula cloud condensed into dust particles and snowflakes. The orbiting particles collided with each other, and because of the stickiness of the ice, and the organic tars coating the dust — they formed a flat disc of swarming planetesimals, objects ranging in size from a few yards across to several miles.