Oumuamua and Solar Sails


Fascinating interview (archive) with Avi Loeb, head of Harvard’s astronomy department and author of the Oumuamua research paper that swept the interwebs last year:

The “spaceship” in question is called Oumuamua. For those who don’t keep up with space news, Oumuamua is the first object in history to pass through the solar system and be identified as definitely originating outside of it.

Avi Loeb:

“What we have, then, is a thin, flat, shiny object. So I arrived at the idea of a solar sail: A solar sail is a spaceship that uses the sun for propulsion. Instead of using fuel, it is propelled ahead by reflecting light. In fact, it’s a technology that our civilization is developing at this very time.”


“We have no way of knowing whether it’s active technology, or a spaceship that is no longer operative and is continuing to float in space. But if Oumuamua was created together with a whole population of similar objects that were launched randomly, the fact that we discovered it means that its creators launched a quadrillion probes like it to every star in the Milky Way. Of course, the randomness is significantly reduced if we assume that Oumuamua was a reconnaissance mission that was deliberately sent to the inner solar system – namely, to the habitable region where life would be feasible. But we need to remember that humanity didn’t broadcast anything tens of thousands of years ago, when the object was still in interstellar space. They didn’t know there was intelligent life here. Which is why I think it’s just a fishing expedition.”


“It’s possible that space is filled with sails like these and we just don’t see them. We only saw Oumuamua because this is the first time we’ve had technology that’s sensitive enough to identify objects of a few dozen to hundreds of meters in size from the illumination of the sun. In three years, the building of the LSST telescope will be completed. It will be far more sensitive than Pan-STARRS and certainly we will see many more objects that originate outside the solar system. Then we’ll find out whether Oumuamua is an anomaly or not.”


“Today, thanks to the Kepler Space Telescope, we know that there are more planets like Earth than there are grains of sand on all the shores of all the seas.”


“The search for extraterrestrial life is not speculation. It’s a lot less speculative than the assumption that there is dark matter – invisible matter that constitutes 85 percent of the material in the universe. The dark matter hypothesis is part of the mainstream of astrophysics – and it is speculation. Life [elsewhere] in the universe is not speculation, for two reasons: (a) We exist on Earth; and (b) There are a great many more places that have physical conditions similar to Earth.”

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