Tiny Ships to the Stars

A billionaire s ambitious plans to send stamp-sized spacecraft light years away

Space—the vast expanse of stars and moons and asteroids and nothingness extending beyond the borders of our small terrestrial home—was once only visited by poets and dreamers in their imagination. Then, in one of the great beneficial side effects of the terrifying faceoff between powerful nations in the last century, human beings began to walk among the stars. The infinity of space became visible and visitable, and we designed bigger and bigger vessels to transport us on more ambitious missions.

More recently, the accessibility of space to humans receded somewhat. NASA abandoned its most powerful rocket and gave up its capability of shuttling people into space. But as the U.S. government stepped back, American private companies pressed forward. Firms like Blue Origin, SpaceX, and others are now pushing the edges of where we go and who or what goes there. Other nations are also getting into space.

Now a new venture created with donated money is beginning to develop space forays. And these are of a new sort: miniscule in size, extraordinarily distant in reach. These experiments could uncover new methods of travel that might eventually take people further than ever before thought practical.

Big gift for tiny craft

On June 23, an Indian rocket lifted off from a spaceport on the country’s east coast. The primary purpose of the launch was to place an Earth observation satellite into orbit. There was enough extra room in the rocket, though, to carry 30 additional small satellites, flying to space as cosmic hitchhikers.

Among those 30 satellites were two built by universities and companies in Germany for science and technology demonstrations. Those satellites in turn had hitchhikers of their own: tiny spacecraft, each the size of a postage stamp and weighing just four grams, called “Sprites.”

Those Sprites, while remaining attached to the larger satellites, are designed to be full-fledged spacecraft, equipped with computers, radios, sensors, and other components needed to operate independently in space. The flight provided an opportunity to test how well those Sprites could function in the harshness of space.

Why build satellites that small in the first place? They may be the key to humanity’s first journeys beyond the solar system within a human lifetime. If all goes as planned, today’s new “Breakthrough Starshot” project could, within a few decades, be sending versions of those Sprites on missions to the nearest stars, even scouting planets that could be habitable.

What sets Breakthrough Starshot apart is not just its advanced technology and its audacious goals. Breakthrough Starshot is not a project of NASA or another national space agency, or even a private company. Instead, it was kicked off as a philanthropic venture by a single billionaire.

Light sailing

On April 12 of last year—the 55th anniversary of the launch of the first human, Yuri Gagarin, into space—another Yuri took the stage at a press conference at New York’s One World Trade Center. Yuri Milner, a Russian-born billionaire now living in Silicon Valley, made his wealth first with a series of Russian Internet companies, then expanded it dramatically with sage early investments in companies like Airbnb, Facebook, and Twitter.

Milner, joined at the press conference by a panel of scientists, engineers, and other experts, said he wanted to accelerate progress in space. “Space travel, as we know it, is slow,” he said. “How do we go faster? How do we go further? How do we make this next leap?”

NASA has already launched several spacecraft that have left the solar system, or are on trajectories that will take them out of it. These include the twin Voyager probes launched 40 years ago. Those spacecraft, though, would take many thousands of years to reach the nearest stars.

What Milner proposed was a technology-development program to allow spacecraft to travel to the nearest stars in as little as 20 years. That is possible, he said, because of advances in several key areas, from microelectronics to nanotechnology to lasers. “The Breakthrough Starshot concept is based on technology either already available or likely to be available in the near future,” Milner said. “But as with any moonshot, there are major engineering challenges to solve.”

The concept involves development of those stamp-sized Sprite spacecraft. Each would deploy a small “lightsail” about a meter across. A giant laser array on Earth, with up to 100 billion watts of power, would fire at the sails, accelerating them to speeds as high as 20 percent of the speed of light.


Businessman and philanthropist Yuri Milner aims to radically extend mankind’s reach into space by means of stamp-sized spacecraft that can reach other stars in just 20 years.

Each Sprite, which the project also calls a StarChip, would be an individual spacecraft, with all the tools needed to collect data on the star systems they fly past. “We can equip this smart electronics with all kinds of probes, and the idea would be to collect data that cannot be acquired from the Earth,” says Avi Loeb, a Harvard University physicist who also serves as chairman of the project’s advisory committee.

The idea of massive lasers pushing chip-sized spacecraft to other stars sounds like something out of science fiction. Yet the concept has been studied for years. “The laser technology has advanced to such a state, along with other technologies, that it’s actually quite feasible to send a very small probe—a few grams—at some reasonable fraction of the speed of light in the next few decades,” says Pete Worden, executive director of Breakthrough Starshot.

Worden, who handles the day-to-day operations of the project, is perhaps uniquely suited for this job. A retired Air Force general with a Ph.D. in astronomy, he worked on advanced-technology programs throughout his military career, from missile defense to a small spacecraft mission to the Moon in the 1990s called Clementine. Later, he spent nearly a decade as director of NASA’s Ames Research Center, the agency’s outpost in Silicon Valley, supporting small-satellite and other programs, and building up relationships with the companies in the area.

Milner’s $100 million donation will go toward studies of some of the key technology issues, from the development of Sprites to nanotechnology needed for the lightsails to developing arrays of lasers that can operate together at the required power. The project will also study other issues, like the policy challenges of operating a giant laser that, if misused, could damage satellites in Earth’s orbit. “This looks good enough that Mr. Milner committed $100 million to begin the research on it,” Worden says. That included the test of the Sprites on the satellites launched in June, as well as upcoming calls for proposals to fund research on lasers and lightsails.

But that $100 million, as large a sum as it is, is just a down payment on the overall project: Worden and others estimate developing the various systems needed for sending StarChips on interstellar journeys could easily cost $10 billion or more. That likely means that future development will involve governments as well as private funding sources. First, though, Breakthrough Starshot will explore how feasible the project is. “There are, to be sure, formidable challenges to this. It’s going to take a lot of work,” he says. “But we’re very excited about that effort.”

“There are many challenges in this project. It’s an ambitious project, but we don’t see any dealbreakers based on fundamental physics principles,” Loeb says. “So we think we can overcome these challenges with enough innovation and ingenuity.”

Are we alone?

Breakthrough Starshot is not Milner’s first space-related philanthropic program. In 2015, he announced Breakthrough Listen, a ten-year, $100 million effort to fund projects that monitor radio and other signals from space for signs of other civilizations.

Milner’s donation breathed new life into that work, which had operated on shoestring budgets since Congress canceled NASA funding for it in the early 1990s. Breakthrough Listen has used his money to purchase time on radio telescopes around the world, and to develop advanced computer systems to more efficiently process the data those telescopes collect.

On a smaller scale, Milner is also supporting a project to study the star nearest the Sun, Proxima Centauri. Astronomers discovered a somewhat Earth-like planet orbiting that star in 2016. Milner is funding development of an instrument to be used on telescopes at the European Southern Observatory in Chile to see if that planet, or potentially others orbiting the star, has any of the qualities needed for habitability—making it a likely early destination for Breakthrough Starshot.

Before those projects, Milner established the Breakthrough Prize in 2012, which offers multimillion-dollar awards in physics, life sciences, and mathematics. While initially funded by Milner, others philanthropists, including Facebook founder Mark Zuckerberg and Google co-founder Sergey Brin, are now also funding the prizes, which have funneled about $200 million to dozens of scientists at the leading edges of their fields.

Worden first met Milner through the Breakthough Prize effort, when the foundation asked to hold the prize ceremony at NASA Ames. Milner later talked with Worden about his ideas for what became Breakthough Listen and Breakthrough Starshot. Over time, “he started chatting with me about another part of his vision, which is really a renewed and well-funded private search for life in the universe,” says Worden. That convinced Worden to leave NASA and become chairman of the Breakthrough Prize Foundation.

Worden said all these efforts are tied together by a single theme that is one of humanity’s most fundamental questions: are we alone? “I think in the next few years, either we’ll find a life-bearing planet around one of the nearest stars,” he says, “or we’ll find some evidence of life in our own solar system.”

Star checks: the next generation

Milner’s twin $100 million projects are the biggest philanthropic space initiatives today. They are, though, part of a larger trend of private funding of space projects once solely in the domain of government agencies like NASA. These surges of philanthropic and for-profit effort are driven by a desire to do more missions more quickly than what governments can accomplish, and powered by growing technical and commercial capabilities that put more and cheaper missions within the reach of private funders.

Szabolcs Marka is a professor of physics at Columbia University who studies gravitational waves, a prediction of Albert Einstein’s theory of general relativity that was finally confirmed in 2016. He’s involved with a European mission called the Laser Interferometer Space Antenna that will also search for gravitational waves. However, this multibillion-dollar mission, first proposed in the 1990s, won’t launch until the 2030s. He thinks private funding could support interim missions that can make advances in the field before LISA launches. “Many of my colleagues are impatient,” he said. “We don’t want to wait 40 years for our dreams to come true.”

There is small but growing interest among foundations and other organizations in funding space missions. “The relationship of the space programs with the foundation community is, it seems to me, where biomedical research was 20 years ago,” says Sandya Narayanswami, former head of the office of foundation relations at the California Institute of Technology.

Narayanswami now works as a consultant advising organizations seeking to raise money for space missions. “It’s still at a very, very early stage, and it’s evolving,” she says of the relationship between space projects and philanthropy. “It’s hard for me to predict where it will go.”

Space projects have to fight a perception that such efforts are still solely in the realm of government agencies. Jon Morse knows that all too well. The former head of NASA’s astrophysics division, responsible for missions like the Hubble Space Telescope, he has been spending the last several years running the BoldlyGo Institute, which seeks private funding for space telescopes and other missions that don’t fit in NASA’s budget today.

When he’s contacted foundations, he often gets the same response. “So far, what we have found is that when we approach a lot of people, they say, ‘Well, isn’t NASA doing this?’ ” He answers, “Yes, NASA’s doing things, but there’s room to do a lot more.”

Similarly, the B612 Foundation—named after the asteroid in Antoine de Saint-Exupéry’s The Little Prince—sought to raise money for a space telescope called Sentinel to look for asteroids near the Earth that could pose an impact risk. B612 started Sentinel in 2012, hoping to raise the $500 million needed for the mission to launch as soon as 2017.

By this year, though, B612 had raised only a tiny fraction of that total cost. The organization announced in June it was abandoning Sentinel and focusing instead on small spacecraft missions to augment NASA’s asteroid search efforts. “We think it makes more sense for us to focus on these smaller, but more numerous, asteroids,” says Ed Lu, co-founder of the B612 Foundation.

Men and women working on space projects hope that Milner’s new funding of Breakthrough Starshot and related projects can open the door to philanthropic funding of other proposed missions as well. This would be a fresh approach, but also a return to the way space science was done long before the launch of the first satellite.

Alexander MacDonald, a NASA economist and author of The Long Space Age, sees parallels between this new interest in philanthropic funding of space ventures and projects in the nineteenth and twentieth centuries to build astronomical observatories with donated money. He studied 40 such observatories developed in the United States through World War II by philanthropists. “If you add up how much private capital was involved in the construction and operation of those observatories, the total is over $9 billion” in present-day dollars, he says. For perspective, NASA’s annual budget this year was $19.5 billion.

Philanthropic funding of space projects like Milner’s Breakthrough Starshot could be the next great contribution of private donors to the science of astronomy. “Our funders are high-net-worth people, all of whom made their resources in the high-tech area, and I think a lot of them feel it’s important that they provide something back as a legacy,” says Worden. “Certainly for Yuri Milner, that’s his objective.”

Only in Milner’s case, his legacy will not be an observatory on a mountaintop but, instead, a spacecraft the size of a stamp speeding toward another star system.

Jeff Foust is editor of the Space Review.