Starts With A Bang

Ask Ethan: Could an atmosphere slow down a runaway spaceship? (Synopsis)

Image credit: Breakthrough Starshot, of the laser sail concept for a “starchip” spaceship.

“Yes, now there is this technological path. But it’s just starting.” -Mae Jemison

Earlier this month, Yuri Milner and Stephen Hawking teamed up to announce the Breakthrough Starshot, a $100 million investment in technology that would build a laser array to propel a thin, light “laser sail” spacecraft to approximately 20% the speed of light. If we can achieve these speeds and sufficiently aim these sails at the nearest star systems, we’ll arrive at our destinations within a single human lifetime.

Illustration of an exoplanetary system. Image credit: NASA/David Hardy, via

But we’ll still be going at 20% the speed of light when we get there, or about 1,000 times as fast as the meteors that burn up in our own planet’s atmosphere. Is there any chance for slowing these spacecraft down once they arrive, or are they doomed to burn up (or miss completely and leave the galaxy) upon arrival?

Depiction of the Earth-grazing meteor of 1860, by Frederic Edwin Church. Image courtesy of Judith Filenbaum Hernstadt.

Find out what physics has to say about it on this week’s Ask Ethan!