When Philip Lubin was a little boy, he would stare at the night sky and wonder where it all came from.
Decades later, Lubin, now a physicist at the University of California, Santa Barbara, has a plan to get some answers. And he doesn’t mind that it might take several more decades before it delivers its first data.
In fact, Lubin is counting on it taking that long. That’s the only way humanity could afford it.
Lubin’s Starshot initiative aims to launch into orbit a bunch of tiny “StarChip” spacecraft, each weighing a gram, and blast them out of a huge laser cannon.
The laser would propel the StarChips as fast as 20 percent of the speed of light, or 37,000 miles per second, toward the Alpha Centauri star system, our own solar system’s nearest neighbor, slightly more than four light years away.
Arriving decades after launch, the nanocraft could survey Alpha Centauri or some other alien star system, gathering data and beaming it back to Earth by way of their own on-board lasers.
“Why are we here? Why does the universe exist? What’s the purpose of it?” These are some of the questions we could then begin to answer, Lubin told The Daily Beast.
Starshot might sound like science fiction, but Lubin said all the basic technologies for the initiative—tiny spacecraft, ultra-thin “light sails” that capture the laser blast, and the propulsion lasers themselves—already exist.
Billionaire Yuri Milner in 2016 signaled his own confidence in Starshot when he and the late physicist Stephen Hawking announced that Milner’s Breakthrough Initiatives organization would sponsor Starshot to the tune of $100 million.
Starshot’s first major test took place a year later, when engineer Zac Manchester launched into low orbit several 3.5-centimeter-square “sprite” spacecraft in 2017.
“These vehicles are the next step of a revolution in spacecraft miniaturization that can contribute to the development of centimeter- and gram-scale StarChips,” Breakthrough stated.
Light sails are undergoing their own orbital test, thanks to the efforts of a separate program. In June, the nonprofit Planetary Society in California launched its latest, crowdfunded LightSail 2, which it claims is the first spacecraft “propelled solely by sunlight.”
LightSail 2’s 344-square-feet sail captures sunlight where Lubin’s StarChips capture an aimed laser, but the vehicles otherwise are similar in their basic concepts.
Light-sail tech is elegant in its simplicity. Photons from the sun or some other light source bounce off a mylar sheet, slowly, steadily, and cheaply accelerating the attached spacecraft.
“Over time, the acceleration provided by sunlight can allow the spacecraft to greatly increase its velocity, allowing spacecraft to reach the outer edges of the solar system in a shorter time than missions using traditional chemical propulsion,” David Spencer, the LightSail 2 mission chief, told The Daily Beast.
The best part? “No fuel required,” Bruce Betts, LightSail 2’s program manager, told The Daily Beast. A spacecraft’s velocity and endurance aren’t limited by how many rockets you can pile under it.
LightSail 2 currently is in orbit, undergoing a few final tests before unfurling its sail. So far, so good. “We have a stable, healthy, communicating spacecraft,” Betts said.
But Starshot would push the same tech to a crazy extreme. “With the LightSail program we are working the near-term of solar sailing, particularly in small spacecraft,” Betts explained. “Starshot is working on some of the many challenges tied to a long-term interstellar vision for solar sailing.”
Spencer said Starshot would need to make several technological “leaps” in order to work.
“Pointing the laser accurately enough to give a precise push to a chip-size spacecraft, and keeping the spacecraft oriented properly so that the push from the photons propels it in the right direction are the key challenges,” Spencer told The Daily Beast.
“Perhaps more importantly, the capability of the chip-sized spacecraft is a question. Can it communicate information back to Earth? Communication systems typically require large apertures or large power. If the chip-sats can’t communicate back to Earth, what is their purpose?”
“My read of the concept is that the technology is feasible,” Spencer said. “I’m not sold yet on the value of the mission.”
Lubin said Starshot’s main obstacle is cost and scale. The 100-gigawatt propulsion laser—perhaps the biggest directed-energy device anyone ever has planned—is actually a cluster of many individual lasers all firing together.
While today’s lasers are highly efficient, they’re also expensive. The U.S. Army plans to spend around $140 million building a single, 100-kilowatt laser for testing. Lubin would need a million of them. Today that could cost a hundred trillion dollars.
“This program faces an economic scaling issue which is quite formidable,” Lubin said. The only way Starshot will work is if lasers get cheaper. A lot cheaper.
Fortunately for Starshot, that’s exactly what’s happening. Moore’s Law famously asserts that computers double in processing power every two years while their cost shrinks by half. The same “law”—actually, it’s an observation, Lubin pointed out—seems to apply to lasers.
At the current rate of decrease, the price of 100-gigawatt laser could become affordable in a few decades, Lubin said, at which point he and his team or their successors actually could assemble the Starshot hardware and start launching nanocraft. “Realistic deployment is probably three decades off,” Lubin said.
Of course, “affordable” is a relative term. Lubin declines to specify how much Starshot might cost even 30 years from now, but he said he expected it would consume around as much resources as the Apollo program did.
Apollo, which in 1969 landed human beings on the moon for the first time, set back U.S. taxpayers around $150 billion in 2019 dollars.
Is Starshot worth it? “It’s important for me for humanity to explore the universe,” Lubin said. But no one should expect quick results.
“The modern world, most of your readers, they’re addicted to the digital world,” he added. “If you can’t get it in the next five minutes, they don’t want it.”
With Starshot, Lubin said he aims to satisfy a deeper, more ancient and more lasting curiosity. “When you look up at the sky and see something mysterious that you don’t quite understand.”
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