The TOLIMAN mission - The search for a habitable planet around Alpha Centauri A and B

The TOLIMAN mission targets a singular question in astronomy and astrobiology: does Earth’s immediate neighbour star system, Alpha Centauri AB, harbour any rocky planets in a temperate orbit? Despite decades of development and manifest success in exoplanetary discovery, contemporary astronomical techniques have made few inroads into this question. The TOLIMAN mission exploits a distinct detection strategy: narrow-angle relative astrometric monitoring. When performed at extremely high precision, measurement of the separation of the Alpha Centauri A/B binary pair will betray the presence of any orbiting exoplanets by the subtle gravitational perturbations that they impose on the binary orbit. Witnessing these deflections, however, requires measurement precision at the microarcsecond level. Recovering such signals while restricting mission size and cost to fit within a 16U CubeSat form factor presents many scientific and technical challenges. A novel optical configuration featuring a diffractive element at the entrance pupil to a highly stable silicon carbide telescope of 125mm aperture has been developed for this task. Science requirements drive performance of thermal, pointing and data handling systems towards those found in billion-dollar class space agency flagship missions, yet must be accomplished within strictly limited mass and budget constraints. This paper provides a brief overview of the TOLIMAN mission beginning with its audacious scientific ambition, and flowing down to engineering solutions that will enable its novel optical system to deliver science not obtainable any other way. With most major subsystems now either manufactured or under contract, a successful launch later in this decade will position TOLIMAN to showcase what can be accomplished with a low-cost, bespoke mission founded on innovative principles.