Hundreds of astronomy enthusiasts filled every available seat to listen to Astronomy Department Chair Abraham “Avi” Loeb describe recent innovations in the search for life beyond our solar system.
Loeb, who chairs the Breakthrough Starshot Initiative, presented to the packed house in the Harvard-Smithsonian Center for Astrophysics’ Phillips Auditorium on Thursday.
The Breakthrough Starshot Initiative, founded in 2015 by investors Yuri and Gloria Milner, is a “$100 million research and engineering program aiming to demonstrate proof of concept for... ultra-light unmanned space flight at 20% of the speed of light,” according to the initiative’s website.
Space flight at this speed would allow a flyby mission to reach Alpha Centauri, the nearest star system to Earth, within our lifetimes, reducing a mission that would have taken tens or hundreds of millennia with current rocket propulsion technology to just a few decades.
In particular, astronomers hope to photograph Proxima b, a planet which — according to Loeb — sits at just the right distance from Proxima Centauri, a dwarf star in the Alpha Centauri system, to potentially have liquid water on its surface and thus sustain life.
Loeb began his lecture by explaining his belief in the “cosmic modesty principle.” According to Loeb, Earth is probably not the only planet to contain life, due to the sheer size of the universe.
“If you realize that a quarter of all the stars are hosting habitable Earths, then there are more habitable planets in the observable volume of the universe than there are grains of sand in all the beaches on Earth,” Loeb said in his lecture. “An emperor or king…boasting about a piece of land here on Earth is no more different than an ant that is hugging a grain of sand on one of these beaches.”
Loeb said in an interview Monday that one of Breakthrough Starshot’s greatest challenges is designing a lightweight spacecraft that can travel at a fifth of the speed of light. In order to reduce excess weight, according to Loeb, the spacecraft must only contain necessities, including a camera, a navigation device, and a communication device.
“[Our spacecraft prototype is] based on a sail that is being pushed by light,” Loeb said.
According to Loeb, scientists plan to shine a powerful laser on the spacecraft and accelerate it “over a distance that is roughly five times the distance to the Moon” until it reaches the desired speed, giving the craft enough energy to travel to Alpha Centauri.
“The amount of energy that you need to invest in this launch process is similar to the liftoff of a space shuttle,” Loeb said. “Except now, the concept is to deliver it to just a few grams of material — that’s why it reaches a much higher speed — instead of many tons.”
Loeb said the Breakthrough Starshot Initiative is in the “first baby steps” of a three-phase process, which include the feasibility phase, where scientists attempt to demonstrate the technology; the testing phase, where scientists build a prototype of the spacecraft; and the launch phase, the culmination of the scientists’ work.
He compared the cost of the final phase to that of “the biggest science projects that are currently funded, like the James Webb or the Large Hadron Collider.” Looking ahead to the future, Loeb said international collaboration would be yet another hurdle of Breakthrough Starshot, even after the scientific and technical challenges are resolved.
Loeb emphasized the immediacy of the initiative, referencing a statistical analysis that compares the likelihood of extraterrestrial life existing in the present versus in the distant future.
“If you allow life to exist only around stars similar to the Sun, you find that being here and now is the most likely thing,” Loeb said. “We are here and now. Perhaps that says something.”
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