Dangerous Journeys

Back in April, Stephen Hawking and Russian space enthusiast Yuri Milner revealed a new initiative meant to probe our closest interstellar neighbor—Alpha Centauri. Named Breakthrough Starshot, the project aims to use small probes propelled by lasers to reach the star system.

Credit: Breakthrough Starshot

But the reality is, these small crafts will be encountering a lot of dangers along the way. The team behind Breakthrough Starshot has just published some of the obstacles that the probes will be facing in their journey.

Unlike other spacecraft, these probes are unusually delicate: their components are just a small chip carried by a light sail. No storage, no compartments, no big metal shielding. And they will be in for a rough ride. The proposal is for powerful ground-based lasers to push the craft towards speeds up to one-fifth of the speed of light.

Bumps on the Road

The study identifies several dangers on the way to Alpha Centauri. Chief among these is the danger of interstellar dust particles that could collide with the craft. A dust particle just 15 micrometres wide would destroy the spacecraft, since it is traveling at such fast speeds.

Even if no particles of that size are encountered, the craft is still expecting erosion of its outer layer by around 0.5mm and possibly even some melting, due to the smaller dust particles. Even interstellar gas could damage the probes. Collisions with heavy gas particles could bring as much as 0.1 mm damage. By the time the probes reach Alpha Centauri, they'll have lost 30% of their weight.

To mitigate this, the scientists are proposing a few millimeters of "dumb" graphite as shielding for the craft. Also, the sail would have to be folded during the journey, to minimize surface area.

The craft should survive the erosion thanks to all of this prepping. However, if it encounters anything unexpected (angry aliens?) it could be in trouble.

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