Our First Interstellar Mission: Breakthrough Starshot

I had the opportunity to speak with Pete Worden, the director of the Breakthrough Initiatives, aiming to leverage cutting edge technology to enable interstellar travel of automated probes, the Starshot project.

Pete Worden, the head of the Breakthrough Starshot initiative, has always been fascinated by the idea of interstellar travel. He believes that now is the right time to attempt turning this science fiction concept into reality. The initiative has identified laser-driven light sails as the most promising method for sending probes to nearby star systems within this century.

Summary of our conversation

• Breakthrough Starshot has been assessing the feasibility of the mission by addressing major challenges such as building cost-effective, high-power lasers, developing lightweight and durable light sails, and enabling communication from nearby star systems back to Earth. While there is still work to be done, Pete and his team believe these problems are solvable.
• Pete emphasizes the importance of building prototypes and incorporating new developments, rather than relying solely on the traditional technology readiness level framework. He also believes in the power of private philanthropy to take big risks for potentially groundbreaking payoffs, which governments are often unwilling to do.
• The Breakthrough Initiatives aim to inspire people around the world by demonstrating the possibility of an unlimited future and expanding human civilization to the stars. Pete argues that space exploration and science can provide keys to solving major problems on Earth, and that pursuing these aspirations should not be seen as mutually exclusive with addressing immediate concerns.
• Pete highlights the value of public-private partnerships in advancing space exploration, with private philanthropists taking on early risks and governments providing support for large-scale facilities. He also emphasizes the importance of involving the public through citizen science projects and educational opportunities related to the Breakthrough Initiatives.
• Regarding the search for extraterrestrial intelligence (SETI), Pete notes the ongoing efforts to use AI in analyzing data and the potential for discovering truly alien civilizations. While he is cautious about actively sending messages into the universe, he believes that the scientific search for alien life is a worthwhile endeavor.

Edited transcript

David: Pete Worden, thank you very much for being with me here today. You are heading the Breakthrough Starshot initiative, which is our first serious attempt for an interstellar mission. Why did you decide that, as crazy as it still is, this was the right time to attempt to turn science fiction into reality?

Pete: I’ve always had a strong interest in going to the stars, since I was a little boy in the 1950s. The first books my mother gave me were on wonders of the stars and wonders of the planets. I thought the stars were a lot more interesting. I asked her, I think at the age of six, what do people do that study the stars? She said they’re called astronomers. So I was pretty insistent I wanted to be an astronomer. Of course, I was a teenager during the Apollo program and felt it was only a matter of time before we developed technologies that would enable us to at least send probes, and maybe even eventually send people, interstellar distances. When I worked with NASA, I kept pushing various interstellar ideas. As an astronomer, one of my strongest interests is nearby stars, particularly if we can find planets there. So it was a natural opportunity when the founder of the initiative, Yuri Milner, told me he was very interested in figuring out how we could send probes to the nearest stars this century. I jumped on the opportunity.

David: The challenges that Breakthrough Starshot has to solve are still numerous – in propulsion, in engineering the probe, and so many others. How do you evaluate the progress being made on each? And how do you organize the collaboration that is needed among so many different disciplines to ensure concrete progress is achieved?

Pete: We’re just completing our first phase, which was a fundamental assessment of the feasibility of the mission. The very first phase was figuring out which method to use. Frankly, the only one that looked promising this century was laser-driven light sails. You would accelerate a very small spacecraft attached to a light sail with a very powerful laser to 20% the speed of light.

When we started this program, we came up with about 25 major challenges – what our sponsor called “deal breakers.” Most of them appeared to be eventually solvable, but there were three or four major ones that the whole feasibility hung on. The first one was: Can you build a laser that’s 100 gigawatts of power or more for a reasonable amount of money? Initially, this was probably the most serious challenge. If you looked at what it costs to build lasers today, that laser photon engine, which provides the propulsive power, would cost hundreds of billions of dollars. That’s unlikely anybody’s going to spend that much money for interstellar probes.

So a lot of our research was looking at the trends in laser technology. There are two things we looked at. One was fiber laser technology, which seems to be advancing. In a decade or two, we think we can build fiber lasers for 10 to 20 cents a watt. That’s still a pretty expensive system. But there are new photonic laser technologies that are basically solid state laser devices, more like electronic chips than classic lasers. Those seem to be coming along quite well, and we think we can get the cost down to under a penny a watt. So that one looks very promising. Clearly there’s still a lot of work to validate it, but that was the first challenge.

The second challenge was the light sail itself. Can we build a light sail that can withstand that much power? We ended up looking at a lot of different materials. This was led by Professor Harry Atwater at Caltech. He came up with a material, silicon nitride I believe, that does have the necessary characteristics. He also proposed that rather than attaching a chip, which is the electronic satellite component, you actually distribute the functions on the sail itself. He’ll soon publish a rather interesting set of papers that will talk about how we can build a light sail that actually is also a spacecraft. This has revolutionary potential not only for eventual interstellar missions, but for missions to the outer solar system, because they’re very cheap and can be moved along quite rapidly. The technology is probably a decade away from where we can begin to do interesting research.

The third effort, and this is probably the one I always thought was the most challenging, is: Can we communicate back from nearby star systems, particularly Alpha Centauri? That’s a big challenge. But there are sort of two aspects. One is having a communications laser actually integrated in the light sail. After the system flies by a target planet in the Alpha Centauri system, the light sail would turn around, lock on the position where Earth will be in four and a half years, and start transmitting the signal with very small onboard lasers.

The real challenge is when you get back to Earth, how do we receive that? You basically have to have a receiver that’s half a kilometer in size if the transmitter is several kilometers. And that’s an optical telescope. Of course, if you build something that large with today’s telescope technology, that would also cost hundreds of billions of dollars. But there’s new technology being developed. We looked at two places – one at the University of Arizona under Professor Roger Angel, a very clever approach, and also Professor Jeff Kuhn at the University of Hawaii had a good approach. We think this makes it possible to build a half kilometer square optical receiver for something like a few billion dollars. That has a lot of revolutionary capabilities as well.

So I guess we would say that we think these problems are all solvable. We have to see where our sponsor wants to go from here. We’re right in that review process now. We expect later this year we’ll have a major set of papers that will describe this. Hopefully our sponsor will agree to get started on the second phase.

David: There is an established framework for evaluating the development of certain approaches, and it is the analysis of the technology readiness levels. Is that approach appropriate for achieving big breakthroughs as this mission requires, or is that potentially too conservative? Do you need to think differently about how to distinguish between an idea that just sounds crazy but actually is going to be reality?

Pete: The technology readiness level (TRL) is a useful construct for considering where you are with a particular technology. But I’m not sure that for something this radically different, it’s the right approach to take. We certainly can characterize the technologies I just talked about and others in terms of TRL. But to my mind, it’s more important to think about whether you can build a subscale model or prototype and actually build it so you can begin to incorporate new developments as they come along. So I guess the answer is yes to both things – TRL is useful, but I wouldn’t say we’re wedded to it.

David: In terms of new ideas, people in any specialty tend to communicate to outsiders that they have an intuition about their field. However, that is hiding how experience allows them to evaluate things and it is not useful for those who would like to be able to emulate the success of those who have been good at this. How would you characterize your own way of looking at new ideas and seeing if they are promising or just crazy?

Pete: Those are interesting questions. The classic way we judge any new concept is you publish it and it’s peer-reviewed. The problem I have with peer review is that if you’re doing revolutionary game changers, usually the peer reviews aren’t very positive. We’ve seen some of that when we go and talk to experts. When they first look at this, they may spend a few tens of minutes and say it’s all ridiculous. And that’s based on their experience.

So I think there’s a bit of a different approach where you begin to say, look, we’re convinced this is feasible. We’ve asked people that we respect, but that doesn’t necessarily mean we go to the biggest critics and publish our results to convince them. There’s also a sense that you should come up with something and build it. A good example of how this is done is Elon Musk’s new approach to rockets. When he first said he could build rockets an order of magnitude cheaper, everybody laughed and said that’s ridiculous. But now he’s shown that he can do it. Maybe it’s not as cheap as he originally targeted, but if he said it was going to be 10 times cheaper, it’s probably seven or eight times cheaper.

So I think you need somebody that is empowered, either by their own resources or by somebody else, to ignore the standard criticisms and just move forward. That doesn’t mean if you’re violating laws of physics that you just press ahead regardless. But it does mean that the classic approach of waiting until everybody else agrees it can be done doesn’t get you to revolutionary capabilities. It gets you to evolutionary capabilities.

David: I’m glad you brought up the capabilities of SpaceX, because what we are seeing almost daily these days, these rockets that land, bring tears to my eyes just seeing them. They have been science fiction until yesterday. And they are really inspiring. So is it true that one of the biggest benefits of a project like Breakthrough Starshot could also be the inspiration it provides to thousands or millions of people, why not billions, that it could represent a new age of exploration and human capabilities?

Pete: The idea of going to the stars inspired a little boy in the 1950s, and I think there are hundreds of millions of little boys and little girls, and maybe big boys and big girls, around the world that are very much inspired by the idea that there’s an unlimited future. If you read any newspaper, it’s full of war and environmental crises and inequalities and so forth. To me, one of the most important things about going to the stars is it provides a positive possibility that we have an unlimited future.

In some sense, the inspiration says, okay, we might not get there in our lifetime or even our children’s or grandchildren’s lifetimes, but we are going to get there. It’s a direction that, among other things, we’ll learn incredible things from. We’ll probably start answering the question of whether there is life in the universe, which is what the rest of the Breakthrough Initiatives do. But maybe more importantly, it’s the idea that there’s a positive future. This was Stephen Hawking’s key point in some of his last writings, the short answers to the big questions. He talked about how unless humanity eventually figures out how to expand our civilization to the stars, we’ll probably fail and go the way of the dinosaurs. So this is a positive inspiration. It has been to me. And whenever I talk to people around the world, no matter where they are, this is a very important point that motivates young people, old people, you and me.

David: There are those who say that until we solve all the problems on Earth – hunger, poverty – we should not aim for the stars. While we are both on the side of those who don’t believe this is the case, how can we tell them that it is not a question of doing just one thing at a time, that we have the opportunity and the duty of attempting to fulfill the aspirations of each of us in a complementary way, that this is not an either-or situation?

Pete: This question comes up all the time, and my first emotion is to get angry. But I think there’s a legitimate concern. The first point is that there are a lot of things that make us human that don’t solve problems. Literature, art, even science itself – the search for knowledge – these don’t have immediate benefits in terms of solving the big problems. On the other hand, they’re what makes us human and inspires us. So I think it’s a bit arrogant for somebody to say, we’ve got this problem that I think is important, and if you don’t want to work on it, we’ll make you do it. I think that’s the wrong approach. We need to have a broad civilization that expands.

Second, and this may be equally important, space exploration and space science may actually provide us keys to solving some of these big problems. There are a number of areas that I’m interested in and others are interested in where perhaps we can even fix climate change and other things from space. Indeed, our current space capabilities are what’s enabling us to understand and manage some things. In the longer run, there may be means for us to actually reverse climate change from space.

So I think there’s both a philosophical answer and a practical one. When you talk to somebody, you should say, look, don’t force people to abandon their dream for whatever the immediate problem is today. And on the other hand, let them explore things that we don’t know about, because they may find the answer that you’ve never thought of to the big problems.

David: In Ashlee Vance’s new book, where you are also mentioned, the journey of entrepreneurs in the private sector is chronicled beautifully. It contrasts somewhat with the original assumption that space would be a realm where only governments would be able to achieve anything. NASA has been quite explicit about concentrating on interplanetary missions and outsourcing low Earth orbit and even moon missions through the latest bids to the private sector. But your project is going even farther. How do you think about the collaboration and also competition between the private sector and the public sector, especially on the frontiers of science and engineering?

Pete: I think the answer here is really a partnership – a public-private partnership. Let me use Starshot as an example. In the next five or ten years, I think much of the work, but not all of it, will probably be done by private philanthropists. Eventually, some of these technologies will have real payoffs, so I think entrepreneurs will take over. But ultimately, this will require a very expensive set of facilities, particularly the photon engine and the receiver. These are many billions of dollars, probably beyond any individual philanthropist.

So one of the things that we’ve increasingly been talking to space agencies and research organizations about is the public efforts beginning to be put into them. I’ll mention there is some work being done in places like Australia on the light sails. There’s research that NASA and the National Science Foundation are pursuing in the United States on these capabilities. So I’d say it’s not either or – it’s a public-private partnership.

I might add, one of the really interesting parts of this is that private philanthropists can take big risks and are inclined to for big payoffs, which governments don’t. One of the other programs that our initiatives have is a search for extraterrestrial intelligence. This started in 2015, and it was announced at the Royal Society on July 20, 2015. Professor Hawking was there, Frank Drake, sort of the originator of the whole SETI effort, Professor Martin Rees, the head of the Royal Society and Astronomer Royal, and others.

Our sponsor, Yuri Milner, asked us what we thought the likelihood of finding an intelligent signal in the next decade was. He went around the room and people said maybe a half a percent to two percent, averaging about one percent. At the end of this, I asked Mr. Milner what he thought the possibility was. And he said, 10 to the minus 5th power (0.00001%). I thought, this is really amazing. If I had gone to the US government and said I wanted $100 million to do some project that the enthusiastic experts thought was 1% likely to succeed, they’d have thrown me out. But here’s a private individual that says, in his opinion, the possibility was even smaller than the experts were saying, but he’s willing to do it because the significance of a positive result would be so earth-shaking for our understanding of the universe we live in that it’s worth it.

So I think that’s where the private sector can take these early big risks that people may actually laugh at, but in the end, sometimes they succeed. So it is really a public-private partnership.

David: The opportunities for the Breakthrough Initiatives to involve the public at large are being leveraged in various ways. Starshot is one of the things that Breakthrough Initiatives is actually promoting. If some of those bright-eyed, enthusiastic people, young or old, are following this, what can they do? How can they turn their enthusiasm into something that either directly or indirectly Breakthrough Initiatives is supporting?

Pete: Let me mention a couple of them. I mentioned the Search for Extraterrestrial Intelligence program. That program is managed currently at the University of California at Berkeley, and we’re opening a new chief management center at the University of Oxford. There are a lot of opportunities to get involved in that. One of the things the SETI program does is SETI@Home, which has been going for a decade. There’s a lot of opportunity to go to the website, it’s called Breakthrough Listen, and get involved. 

For Starshot, we’re hoping to have a center of excellence, probably at Caltech, if we get started. We’ll probably set up some similar sort of citizen science efforts on that. So I would stay tuned for that.

The third program we have is called Breakthrough Watch. It’s where we’re looking for potentially life-bearing exoplanets around nearby stars. For that program, we’re beginning to look at student-built telescopes and small telescopes that can actually contribute to science. 

So I would urge people to look at the Breakthrough Initiatives websites and also our principal investigators’ websites. For example, Professor Atwater’s work at Caltech and others. There are a lot of opportunities for the public to get involved and understand what’s going on.

David: Breakthrough Message is something that would be a little more controversial, if I am not mistaken, because we know so little about the universe that starting to shout without deeper thinking could be a bit problematic. So, as I understand, there are currently no plans to do that within the framework of the Breakthrough Initiatives. But we already have, according to some, alien intelligences that are starting to live among us – advanced AIs. What is your current thinking about the opportunity that these actually give us to understand how to speak to aliens, how to interact with them, how to establish common frameworks of coexistence?

Pete: That’s a very good question. There are a number of different aspects to it. First, you mentioned Breakthrough Message. We initially thought about not sending any messages, but asking people to think about what the message might be. But frankly, Professor Hawking was very concerned that if you think about it, somebody might actually do it. And there are a lot of experts that are worried that drawing attention to ourselves by shouting into the universe might be dangerous. Now, I tend to be more skeptical of that worry, but I think it’s a legitimate one that people talk about. 

Second, to your question about new intelligences, maybe alien intelligences, emerging here based on AI and others – I tend to be a little more skeptical of how alien they are, but nonetheless, we’ve already started using AI for our searches. We look through the database to see if AI can find something that a human looking through it couldn’t. We’ve begun to have some very interesting results. Now, we haven’t found a real signal yet, but we’ve found some things we’ve been looking at that we wouldn’t have found other ways. So I think AI is certainly helpful in finding out if we’re alone.

Now, as far as eventually talking to alien intelligence, to my mind, it’s important to find them first. I also have a hunch that if we find an alien civilization, we will find it to be truly alien. It may take a long time to recognize that it’s a civilization at all. And in the same way, they may find it hard to recognize that we’re a civilization. So to me, this is why science is fun – you don’t know what you’re going to find.

David: Pete, thank you very much for this exciting and enlightening conversation. Good luck for the next stages of Breakthrough Starshot and Breakthrough Initiatives in general. And thank you very much today. It has been really fun.

Pete: Thank you, David. It’s been a pleasure talking to you.