Hyperfast Spacecraft Could Be Partly Destroyed By Interstellar Dust En Route To Alpha Centauri

Concept art of how the craft itself would be powered by a huge sail fired at by ground-based lasers. Credit: Breakthrough

The Alpha Centauri star system, one that contains three stellar objects, is the nearest to our own Solar System. Apart from being extensively studied and of huge interest to astronomers, a recent groundbreaking study has revealed that a terrestrial planet, possibly Earth-like, is hiding there.

This means that Breakthrough Starshot, a project focused on building an interstellar craft designed to reach Alpha Centauri in just two decades – and one that has the backing of Stephen Hawking, Mark Zuckerberg, and Russian billionaire Yuri Milner – has an even greater impetus to get to our neighboring star system just over 4 light-years away.

However, there may be a problem. The craft is designed to reach 20 percent of the speed of light, which means that any run-ins with the tiniest of objects, including interstellar dust, could erode it down to the point of destruction before it even reaches its destination. This is just one of 20 problems identified by Milner’s scientific team, but it could be the most worrisome.

A new study uploaded to the pre-print server arXiv focuses on the potential problem of interstellar dust impacts on the hyper-velocity spacecraft. Led by Avi Loeb, a professor of astronomy at Harvard University, the team assessing this issue conclude that it may erode the interstellar craft somewhat, but it likely won’t be enough to destroy or cripple it.

“We did a thorough analysis, taking all the relevant physics into consideration,” Loeb told New Scientist. “We didn’t see any showstoppers.”

Breakthrough Starshot concept video. Breakthrough via YouTube

The spacecraft, named Starchip, is so unbelievably small that it could fit between two fingers. It will be attached to a huge sail, and an array of lasers fired from Earth will combine to form a beam approaching 100 gigawatts of power that will push the sail forwards until it reaches a fifth the speed of light in a matter of a few minutes.

Whereas conventional craft would take over 30 millennia to reach Alpha Centauri, Starchip will take just 20 years. Instead of sending just one craft out into deep space, Milner plans to send hundreds of them. $100 million is already available for the project, but it will likely cost billions more by the time it is completed.

These “wafersats” are made mostly of quartz and graphite, and thus their properties are well known. Simulating impacts of typical interstellar material on them using pre-existing experimental data and virtual modeling, the team attempted to clarify how much of a problem small grains would be as the little circuit boards traversed the space between stars.

The sail is hypothetically the main problem here in terms of interstellar dust collisions, but the idea is that it will be folded away for most of the trip. Even though the craft itself is incredibly tiny, however, interstellar dust will still impact it.

Although individual grains are small, they will bombard the surface of the craft in collections, which will heat up and form little dents over time. The team estimate that as much as 30 percent of the volume of the craft itself will be eroded by the time it reaches Alpha Centauri.

In order to counteract this, they suggest giving it a thin graphite shield, which will ensure the internal electronics are kept protected on its long journey. If the craft is really unlucky, though, it will impact a micrometeorite, no larger than a hundredth of a millimeter, and be completely obliterated in the process, and there’s little a shield can do about it.

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The Alpha Centauri star system, with Alpha Centauri (left), Beta Centauri (right), and Proxima Centauri, circled in red. Credit: Skatebiker/Wikimedia Commons; CC BY-SA 3.0

[H/T: New Scientist]

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