Almost all of us have dreamt of visiting the stars when we were children. Nothing seemed to fascinate us more than those glowing dots in the night sky. Those dreams were crushed when we learnt about how mind blowing-ly far away stars are from us. But now, with the advent of Breakthrough Starshot, those dreams can potentially become a reality.
The nearest star to us is a small red star about 8 times smaller than our sun called Proxima Centauri. What makes this star even more special is that there is a planet roughly the same size as the Earth orbiting it in its ‘Goldilocks Zone’ which is the area around a star with just the right temperature to keep water in its liquid form. Why is this important? Because liquid water is an essential component for life to exist. Now this star is 4.25 light years away, meaning that with our current technology it will take us a couple of hundreds of thousand years to get a probe there.
There is a way we can get there a little faster, and that is through a project called Breakthrough Starshot. If this project succeeds then we can have small unmanned probes reach 15 to 20 percent of the speed of light. This will let us get the probes to Proxima Centauri in just 20 years after launch. The video below compares the technology to existing means of interstellar travel like ion thruster engines, fusion propellers and inertial confinement fusion based engines.
The probes will only be a few centimeters wide and will contain a camera and communication devices. Around them will be a 4 meter wide ‘solar sail’ made of a very reflective material. Similar to wind sails, these sails will be propelled by an external force and as the name suggests, that force will come from light. The photons of light will transfer some of their momentum to the sails causing them to accelerate gradually like ion thruster engines. There have been many suggestions on how to get large amounts of photons to the probes for example there is a solution is to shoot the probes with an array of high-powered ground-based lasers. These lasers must be very powerful since there need to be enough photons to accelerate the probes to such high speeds and hence the lasers will use about 100 GW of energy per probe. Another option is to position the probes in front of the Sun for the maximum part of the journey, starting from right in front of the Sun itself, given that it doesn’t melt before.
A concept of the probe based on Breakthrough Starshot technology. The sails will function in sync with light as a ship does with wind; a larger surface area of the sails will obviously capture more light and hence push the probe faster
This project isn’t without its set of problems. First of them being, we don’t know how long it will take to figure out all the small details of the project like what the sails will be made of or how we generate enough energy to accelerate a large number of probes. One major problem is that, at those speeds, a collision with even a single dust particle will destroy a probe which is why 1000 will be sent at a time. This increases the cost of the project exponentially.
The biggest concern is the constant supply of light for the increasing acceleration. The 'lasers from Earth' solution is quite unfeasible but remains a popular concept in other science fiction technologies too.
Despite its issues, Breakthrough Starshot is our best shot at getting probes to other stars as of yet, which is why this project is well funded. Russian millionaire Yuri Milner has already given 100 million USD for research. Mark Zuckerberg, Stephen Hawking and many other scientists support this project. It has been estimated that Breakthrough Starshot will be completed in about 15 years and the first probes will be launched in 2036 and will reach Proxima Centauri in 2056.