The Integrity is an exploration/construction ship of the Solar Unity. Although 10km long, most of it is empty truss structure and fuel tanks: the crew of 150 lives in a comfortable adjustable-pitch gravity wheel in the central section (which is, naturally, surrounded by water tanks for radiation shielding).

Its fusion drive produces efficient thrust at 0.1g, and can "switch gears" to thrust at up to 1.2g at far lesser efficiency. Coolant droplets are flung forward and then recollected by magnetic scoops as a radiator. These magnetic scoops can also serve as Bussard ramjets to slow down. There are engines on both sides. The front engine provides thrust, and the rear engine provides heading adjustments. When the ship slows down, they switch roles.

The coolant droplets shield against small interstellar debris. A laser deflects larger debris. The Integrity is not a warship, but you cannot travel at interstellar speeds without a means of vaporising pebbles before they vaporise you.