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The Breakthrough Initiatives Project Starshot proposes to send a gram-scalelaser driven spacecraft to the Alpha Centauri system in a 20 year missiontravelling at v=0.2c. One of the challenges of this mission as the spacecraftmoves through the interstellar medium is the presence of dust and gas (mostlyhydrogen). The dust has a typical matter-density of 2.57*10^-27 g/cm3 withtypical particle mass being 3*10^-13 g although some of the largest particlesmay be 5*10^-9 g in mass. These dust particle will deposit 10^12-10^16 MeV ontothe spacecraft with an energy flux of order 0.3 J/sm2. We consider the erosionof the spacecraft frontal area due to dust and also heating effects. We attemptto characterise the likely environment for the starshot mission and estimatethe particle bombardment shielding requirements in terms of mass and thicknessof material. Current analysis estimates that the likely erosion rates are oforder 10^-11-10^-8 g/s and that the frontal area temperature for the modelsexamined in this paper will be 135.2 K depending on the ratio of frontal areato radiating area. For an assumed shielding material with atomic number range3-13 (Lithium to Aluminium), and for spacecraft geometries with radii ~1 mm andcylindrical length 5 mm, over a 21.5 year mission duration, this would suggesta shielding thickness of 1.4 - 3 mm. This would also suggest a shielding massin the range 0.01 - 0.05 g; depending on the material choice, spacecraft sizeand chosen geometry. This would represent between 1 - 5% of the total mass,assuming a spacecraft mass of 1g (driven by a 100 GW laser power). We alsoexamine the additional effects of charged particles and estimate the stoppingpower and penetration range for different materials.

Calculations of Particle Bombardment due to Dust and Charged Particles in the ISM on the Project Starshot Gram-Scale Interstellar Probe