The TOLIMAN space mission confronts the challenge of detecting Earth analogues in the immediate solar neighbourhood by using novel astrometric techniques. This bespoke, low-cost mission will employ a novel optical and signal encoding system, enabling high-precision measurements that typically require larger instruments. Targeting the Alpha Centauri system, TOLIMAN will utilise an innovative diffractive pupil to mitigate the limitations of a relatively modest satellite and payload infrastructure to make measurements at the extreme precisions required. In this work, we describe the design and manufacturing of the pupil, which employs liquid crystal technologies and substrates with low coefficients of thermal expansion, with the goal of making measurements resistant to inevitable optical distortions and aberrations.
The TOLIMAN space telescope is purpose-built to probe our stellar neighbourhood for potentially habitable Earth-like exoplanets. Our novel diffractive pupil design will allow TOLIMAN to detect extremely subtle changes in the positions of stars in a binary system, down to the microarcsecond scale. One of the many challenging factors in the detection of this diminutive astrometric signal is instability in the telescope pointing, known as jitter.
This work demonstrates the capability of mitigating the blurring effects of telescope jitter through a forward modelling approach and a new precise optical positioning system. We utilise ∂Lux – a cutting-edge differentiable optical simulation framework built in Jax by our team at the University of Sydney – to model the effects of telescope jitter on the final image. The demanding stability requirements have also inspired innovative engineering approaches, including the design of a piezo-driven tip/tilt system. This methodology enables us to recover the crucial astrometric parameters despite telescope pointing instability, offering TOLIMAN the unique opportunity to observe exoplanetary signatures with unprecedented precision.
The TOLIMAN mission will fly a low-cost space telescope designed and led from the University of Sydney. Its primary science targets an audacious outcome in planetary astrophysics: an exhaustive search for temperateorbit rocky planets around either star in the Alpha Centauri AB binary, our nearest neighbour star system. By performing narrow-angle astrometric monitoring of the binary at extreme precision, any exoplanets betray their presence by gravitationally, engraving a tell-tale perturbation on the orbit. Recovery of this challenging signal, only of order micro-arcseconds of deflection, is normally thought to require a large (meter-class) instrument. By implementing significant innovations optical and signal encoding architecture, the TOLIMAN space telescope aims to recover such signals with a telescope aperture of only a 12.5cm. Here we describe the key features of the mission: its optics, signal encoding and the 16U CubeSat spacecraft bus in which the science payload is housed - all of which are now under construction. With science operations forecast on a timescale of a year, TOLIMAN aims to determine if the Sun’s nearest neighbour hosts a potential planetary stepping stone into the galaxy. Success would lay down a visionary challenge for futuristic high speed probe technologies capable of traversing the interstellar voids.
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