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9,642 space probes encounter the light of a new star. They are approaching Proxima Centauri at million kilometers per hour-that's 20% of the speed of light-and year mission in a matter of hours. Ahead is Proxima Centauri b, a rocky world that, by cosmic coincidence, has the same size, mass, and surface temperature as our Earth. Each probe is an autonomous spacecraft the size of a car but lighter than a credit card. On board is a radioactive power source, lasers for communication, computers, cameras and sensors, all of which are hundreds of times thinner than a sheet of paper. All of this equipment will be used only once during the flyby of the planet. To make the most of this one chance, they operate like an intelligent swarm: dividing into
a hundred groups of a hundred probes, spread out over thousands of kilometers, to turn 10- minute shots into a 17- hour photo shoot. Several probes from each group sacrifice themselves in collisions that illuminate the planet like camera flashes. The data is quickly analyzed and transmitted to subsequent probes, allowing new teams to focus attention on the planet's discovered features . Proxima Centauri b lights up, revealing giant storm clouds. Subsequent collisions head into the gaps between the clouds, revealing the outlines of continents and waves crashing against their red shores. This is what our first interstellar
mission might look like. And I will explain how we can make this vision of the future a reality. Let 's go back to today. Our probes crash onto the Moon, Mars exploration is progressing painfully slowly, and we have only visited planets in our system, such as Saturn and Neptune, once or twice. The distances between objects in our system are measured in tens and hundreds of millions of kilometers, and this is already a huge challenge for us. We need expensive rockets and complex trajectories with gravitational maneuvers near planets to cover these distances, and still the probes take years to do so. For example, it
took Juno 5 years to reach Jupiter, and New Horizons a whole decade to fly past Pluto. Exploring other stars is a whole other level. Interstellar distances are measured in trillions of kilometers, a million times greater than the distances we can barely cope with now. Using modern probes for this is unthinkable. So what can we do? We cover great distances with the help of extraordinary speed. If we can accelerate our probes fast enough, we can reach neighboring stars in a reasonable number of years.
Of course, the problem with increasing speed is how much additional energy it requires. New Horizons is currently the fastest probe to leave the Solar System, traveling at approximately 14 km per second. At that speed, it would take 91,000 years to reach Proxima Centauri. If we want to get there in one human lifetime, we need to fly a thousand times faster, which requires a million times more energy. Rockets simply won't cope with this task. No amount of chemical fuel can accelerate a payload to speeds of thousands of kilometers per second. You can do calculations using the rocket equation that shows the amount of fuel needed, and you'll get crazy
results that require a mass greater than the mass of the Milky Way. Even nuclear fuel is not considered an option. A crazy concept for a rocket that would use the energy of a series of thermonuclear explosions would require the equivalent of 2.8 million Tsar Bombs to deliver a probe to Proxima Centauri in a single lifetime. We can't build it, and we wouldn't want to. Fortunately, a solution to the energy problem exists. It is to completely bypass the rocket equation. Instead of loading the rocket with fuel, we deliver energy directly to the payload, and nothing else, using lasers. When light reflects off a mirror, it
transfers some of its energy, which the mirror experiences as recoil. This force is so insignificant that we never feel it in everyday life. It takes a whopping 150 MW of light to create just one newton of force. It's like using the power of a jet plane to lift an apple. This is useless on Earth, but in the frictionless environment of space, it can be used to gradually accelerate a reflective light sail to incredible speeds. This idea, like most movement concepts, is not new. In 1960, the first laser was invented. Millisecond
pulses were squeezed out of a thumb-sized ruby crystal with an average power of less than 1 watt. In 1962, scientist Robert L. Forward described 10- billion-watt lasers pushing 10- kilometer sails beyond the solar system. Others have analyzed concepts where a lens the size of Texas would focus a beam of 75 PW, nearly 4,000 times the total energy consumption of humanity. Actually, that sounds unrealistic. So how are light sails better than a rocket? Laser- powered light sails also have problems. Light pushes so weakly that we need incredibly powerful beams to get a useful amount of thrust. But concentrating such a beam on a small target results in destructive intensity. The only way to survive such
intensity is to distribute the beam over a larger target and make it out of a material that reflects light. But the problem is that nothing is perfectly reflective. Even the best mirrors reflect 99.999% of laser light, with 0.001% being absorbed as heat. A high-performance mirror that can withstand heat is usually very heavy, which means that an even more powerful beam is needed to create thrust, which increases the intensity and exacerbates the heating problem. Getting out of this vicious circle by using a weaker beam and accepting less thrust is also not the best solution. A slowly accelerating light sail will travel millions of kilometers before reaching interstellar speeds, and the laser beam must remain focused on it over that entire distance. If
you follow the mathematical calculations in this direction, you will find that the lens needed to focus the beam would become the size of Texas. It's not physically impossible to build, but we wouldn't build one for our first interstellar mission. Projects like Breakthrough Starshot have been addressing these issues for the past decade, and they are looking for better materials that can withstand such heat. Silicon nitride, for example, is a lightweight, heat-resistant ceramic that actively interacts with laser wavelengths. Using photolithography techniques familiar to microchip manufacturers, it can be shaped into mirrors just 200 nanometers thick. This is just enough to reflect 70% of the laser light, allowing the rest to pass through
. The loss of potential thrust is more than compensated for by the incredible intensity that the mirror can withstand, exceeding 10 gigawatts per square meter. If such intensity were absorbed by ordinary material, it would turn into plasma seven times hotter than the Sun. Ultralight mirrors like these have been tested in laboratories, printed as samples many centimeters wide. They were even able to be made to float on laser beams, defying gravity. Although we have not yet scaled production to meter-sized sizes, this is an area that is at the cutting edge of materials science technologies. More advanced techniques allow holes to be cut into silicon nitride smaller than the wavelength of the laser to further reduce mass while maintaining
reflectivity. Just like the mesh screens in your microwave oven reflect microwaves, even though they have holes in them. All of this will be held by a structure made of aerographite. It's a carbon foam that's seven times lighter than air and 35 times stronger than the next- best silica aerogel. Together, these materials can create a 4 m light sail that weighs just 1 g. Capable of withstanding GW laser beams, it can even carry a significant payload of 1.6 g. So the entire station weighs a whopping 2.6 g. The goal is to accelerate the device to 20% of the speed of light. The next problem is how to create a laser beam relatively economically.
Laser weapon technology combines multiple smaller beams into one high-intensity beam. The 2.8 km wide facility could contain many smaller emitters, combining into a 200 GW laser capable of accelerating a light sail to 12,000 G. It would have to be in the beam for 500 seconds, starting from low Earth orbit. The light sail becomes the fastest spacecraft in history in the first 2 seconds. When the probe crosses geostationary altitude, it travels at a speed of 3,000 km per second. In 80 seconds, it flies past the Moon, approaching a speed of 10,000 km per second. Every critical second must be spent adjusting the beam so that it falls perfectly flat on the light sail.
The slightest imbalance would instantly tip the sail. Nanometer-scale patterns etched into the mirror act as controls, stabilizing the probe so it doesn't drift sideways. And if the probe survives this, it will have another two decades of testing in outer space ahead of it. On the way to Proxima Centauri, there are small accumulations of dust and gas. A collision with this interstellar medium would be a real radiation bath for the probe. The light sail will collide with about 67 mg of high-energy atoms per square meter during its entire flight, releasing a total of 124 gigajoules of energy. This is spread over many years, averaging 184 watts, but because the sail is so thin and has no room for protection, it is a potentially lethal dose. Even
worse, 1% of collisions will be with dust particles. You can turn the light sail with the edge facing the direction of travel, significantly reducing the likelihood of a damaging collision. The Breakthrough Starshot project proposes using tiny LEDs on the edges of the sail as maneuvering engines. The emission of photons creates a recoil that can be used to turn the sail without consuming fuel. But there remains the possibility of a collision, which would result in the end of the mission. So what if You multiply your chances of success. It takes several minutes to launch one probe, but the laser beam can be used over and over again. So in two months of work, 10,000 probes can be sent to Proxima Centauri. Some of them will fail.
Thousands will survive. We can improve their chances by allowing the swarm to communicate with each other using lasers, so that the leading probes can warn the following ones of danger. All of this is based on one critical assumption: that we can fit communications and computing into a 2.6-gram, paper-thin spacecraft, along with a power source and Let's start with the part of the probe that directly performs scientific tasks. How do you take a picture of a planet with a camera that weighs one tenth of a gram? The Breakthrough Starshot project requires a lensless optical phased array antenna with a diameter of 20 cm but a thickness of only 250 nm. Essentially, it's the same phased array technology used in modern fighter jets to detect radio signals using
centimeter-scale antennas, but scaled down 10,000 times to work with light wavelengths. We have working laboratory samples of very thin lithium niobate interacting with electrical contacts made of silicon and gold. This is called an electro-optic metasurface. The samples have already gone beyond laboratories: the Dunn Solar Telescope at the Sunspot Observatory is using the new material to image the Sun's magnetic field. What would normally require heavy, complex, and moving components was achieved with a piece of material thinner than a human hair. However, we are still a long way from creating a device thin or light enough for this application. And any data from the camera will require a computer to process. We need something as smart as the iPhone processor, but a
hundred times lighter. There are ways to produce such electronics. Instead of the usual photolithography process for etching structures into a thick block of silicon, a much better method is used. Direct laser deposition from atomic layers can do this . It all starts with an electron beam focused by a magnetic field into a narrow spot, which we move across the surface to etch patterns with a step of a few molecules. These patterns become chemically active, while the surrounding surface remains neutral. Place these patterns in a vacuum chamber with a sequence of gases, and a layer of semiconductors or metals will deposit right on them. The result is electronic circuits that can be as thin as one atom.
Today, this approach has too many drawbacks. It is very difficult to use more than one electron beam at a time so that the charged electrons do not interfere with each other. Therefore, the recording process is very slow. It is sufficient for creating photomasks for lithography machines, but not for mass production of microcircuits. Atomic layer deposition is another slow and expensive step that is not suitable for large surfaces. Ultra-thin electronics are also fragile, easily corroded, and very sensitive to overheating. Electrical resistance increases as conductors become smaller. Therefore, even a small amount of power passed through such electronics will instantly melt it. But this
shouldn't be a problem, as the probe's total energy budget is only 14 kJ. This is the energy your phone consumes in 2 hours of mindlessly scrolling through your news feed. And the probe receives that much energy for its entire twenty-year mission. Even such a small amount of energy is a serious challenge. The only energy source capable of maintaining a charge for decades is a radioactive source. So, we need to somehow reduce the size of thermoelectric generators, similar to those used on the Perseverance rover. These generators use plutonium-238. This amazing material glows with a red glow. Not for hours, not for days, not for weeks or months, but for decades.
Slow, steady heat release that halves every 88 years. And this heat can be used to generate electricity. The modern method of generating electricity is based on the Seebeck effect. The Seebeck effect essentially allows electric current to be generated through temperature differences. As charge carriers, electrons and electron holes will move from hot to cold. So, if we have two semiconductors, one with charge carriers in the form of electrons and the other in the form of holes, then when a thermal gradient is created between them, a potential difference arises. This causes current to flow in the external circuit. With a flat thermoelectric generator, the probe could theoretically begin its mission with an output power of 1 watt. And we've
made small devices before. Plutonium-238 even powered pacemakers in the 1970s, but a thin version like this has never been made. Next comes a monumental hurdle-transmitting mission data back to Earth. Each probe aims to transmit 100 kilobits of data, the equivalent of 50 "like" emojis. That's not much, but transmitting those bits over a distance of 4.25 light years with only microwatts at your disposal is a daunting task. Our current record for communication range is the Voyager 1 probe, which is only 0.006 light years from Earth. We can also use optical phased array antennas as optical transmitters.
Just as radar can both receive and send signals through the same antenna. Each probe could send light pulses with encoded data, and a swarm of thousands of probes could work together to amplify the signal and guarantee its reception. For example, they could use the reflective back of their solar sails as a mirror and assemble many probes into a giant antenna that focuses light in our direction. Even then, special telescopes would have to be built on Earth to capture this signal. They would use sensitive cameras tuned to the precise signals of the probes, covering an area the size of several football fields. If all went
according to plan, the telescopes would have received their first data 25 years after the probes were launched. So, when can we start? Although all of these technologies are constantly improving, we are not even close to realizing this plan. The $100 million Breakthrough Starshot project Such a project would never get off the ground without global support, especially considering that one country would have to build a 200- gigawatt laser aimed at the sky. And even though access to low Earth orbit has become cheaper than ever, we are somehow doing less space exploration, not more. NASA and ESA budgets are being cut, fewer ambitious missions are being approved, and existing ones, like Juno, are being completed early.
The technology may be ready in a few decades, but the desire to research and the funding for it may come much later. So it's unlikely we'll see this vision of the future in our lifetime. A team of five people worked on this video, and it's becoming increasingly difficult to create videos like this with high-quality animation. We had the opportunity to fund production with dubious sponsors offering loans or therapy apps that sell your mental health data. But I believe that the day I start promoting sponsors I don't believe in is the day I lose a little of my soul. So, to avoid selling junk to our audience and keep these videos free to watch here on YouTube, we launched a Patreon page.
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