The Breakthrough Starshot system model

Breakthrough Starshot is an initiative to prove ultra-fast light-driven nanocrafts, and lay the foundations for a first launch to Alpha Centauri within the next generation. Along the way, the project could generate important supplementary benefits to solar system exploration. A number of hard engineering challenges remain to be solved before these missions can become a reality. A system model has been formulated as part of the Starshot systems engineering work. This paper presents the model and describes how it computes cost-optimal point designs. Three point designs are computed: A 0.2 c mission to Alpha Centauri, a 0.01 c solar system precursor mission, and a ground-based test facility based on a vacuum tunnel. All assume that the photon pressure from a 1.06 mu m wavelength beam accelerates a circular dielectric sail. The 0.2 c point design assumes $0.01/W lasers, $500/m(2) optics, and $50/kWh energy storage to achieve $8.0B capital cost for the ground-based beam director. In contrast, the energy needed to accelerate each sail costs $6M. Beam director capital cost is minimized by a 4.1 m diameter sail that is accelerated for 9 min. The 0.01 c point design assumes $1/W lasers, $10k/m(2) optics, and $100/kWh energy storage to achieve $517M capital cost for the beam director and $8k energy cost to accelerate each 19 cm diameter sail. The ground-based test facility assumes $100/W lasers, $1M/m(2) optics, $500/kWh energy storage, and $10k/m vacuum tunnel. To reach 20 km s(-1), fast enough to escape the solar system from Earth, takes 0.4 km of vacuum tunnel, 22 kW of lasers, and a 0.6 m diameter telescope, all of which costs $5M. The system model predicts that, ultimately, Starshot can scale to propel probes faster than 0.9 c.