Cruise | Interstellar dust

Based on estimates of the density of dust in the local interstellar medium, over the course of a journey to Alpha Centauri each square centimeter of the frontal cross-sectional area of the StarChip and lightsail would encounter about 1,000 impacts from dust particles of size 0.1 micron and larger. However, there is only a 10% probability of a collision with a 1 micron particle, and a negligible probability of impact with much larger particles.

A 0.1 micron dust particle moving at 20% of the speed of light would penetrate and melt the StarChip to a depth of order 0.4mm. To estimate scale effects, calculations were made assuming a 10cm X 0.1mm thickness. Traveling with the nanocraft’s edge facing parallel to the velocity vector would reduce the cross section to 0.1cm2, for a 10 cm StarChip with a 0.1mm thickness. A protective coating of beryllium copper could be added to the leading edge of the StarChip, as a sacrificial layer for additional protection from dust impacts and erosion. If needed, the StarChip geometry could be elongated (‘needle’ geometry), to further minimize the cross-section.

To mitigate the impact of dust further the sail could potentially be folded into a streamlined configuration during the cruising phase to Alpha Centauri. This would minimize the frontal area of the sail. The nanocraft’s electronics could also be designed so as to be less vulnerable to localized damage from dust.

The momentum kick from 0.1 micron dust particles is small, and its effect on the nanocraft’s trajectory might be compensated for by photon thrusters.

Jul 15, 2017 03:30 Breakthrough Initiatives Posted on: Breakthrough Initiatives

Apr 10, 2017 16:14Stuart Heinrich Posted on: Breakthrough Initiatives

Spinning could indeed help mitigate perturbations to the spacecraft’s attitude (orientation), and may be a good idea. However, it won’t do anything to prevent dust impacts from perturbing the sail’s trajectory through space.

- Zac Manchester, Breakthrough Starshot

Nov 15, 2020 01:18 John Weiss Posted on: Breakthrough Initiatives

Don't launch all crafts at the same time. Do multiple launches, staggered by hours, days, maybe years?

What if you hit an asteroid field etc?

Jan 26, 2022 18:21 Breakthrough Initiatives Posted on: Breakthrough Initiatives

Dear John,

The current approach is to launch spacecraft at a cadence of days or weeks. Since the major investment is the laser propulsion infrastructure – and the marginal cost for each successive spacecraft is comparatively low – the beamer should be used for many years.

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