Sunday, May 1, 2022

Navigating Alpha Centauri

Alpha Centauri consists of a binary of two stars, orbited by the red dwarf Proxima. A few days ago Centauri Dreams considered the sail methods of getting (milli-)probes from one sort of star to the next. Per Greg Matloff, the "Solar Sail" - which uses photons - is for hot stars, G+ like our Sun or, for that matter, the main Kentaurân. Proxima doesn't deliver enough light - unless you're in one of its flares, and good luck predicting those. But such M stars do deliver atomic hydrogen, especially from in close. A magnetic sail will work for these.

Where I think this will really shine (as it were) is where the stars are up close to one another. Say Proxima's planet has colonists on its orbital-ring. With modest delta-V the colonists unfurl their sail and zoom off to wherever else around Centauri they need to be. Might "only" take one of Earth's years. When comes time to decelerate they fold up (or jettison) the magnetic sail and use the solar sail.

I doubt the Centauri system has any starfaring life. But systems like Centauri are common. Consider a G star binaried with a red dwarf out, oh, 10000 AU. I can easily see its inhabitants conceiving a multiyear project to "New-Horizons" that dwarf. Currently we don't do this at Earth because our closest system is, exactly, Centauri whither our best "starshot" would take over a generation. But if it just took a decade? No-brainer, for them; we just did it for Pluto.

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