Interstellar travel may not be lightyears away, at least not in the literal sense. Breakthrough Starshot, an international scientific effort, has released an update on its ambitions to launch a probe to Alpha Centauri, our nearest neighboring star system.
Before then, it will have to design and test a new sort of spaceship propulsion system that uses a lightsail and a laser beam array to achieve the enormous speeds necessary for interstellar travel within our lifetimes, according to an Australian National University (ANU) news release.
A voyage across space of 40 trillion kilometers
Breakthrough To reach Alpha Centauri, Starshot’s ultra-lightweight spaceship will have to traverse four light-years. To put it another way, our nearest neighboring star system is 40,208,000,000,000 (40 trillion) kilometers distant from Earth.
As a frame of comparison, the ion thruster, which is propelling NASA’s DART mission to a neighboring asteroid at speeds of 15,000 mph (24,000 km/h), is our fastest and most dependable technology for long-distance space travel today. However, NASA estimates that using an ion thruster would take 18,000 years, or nearly 2,700 human generations, to reach Alpha Centauri.
The Breakthrough Starshot team believes that their spacecraft will be able to attain extraordinary speeds with the aid of lasers placed on Earth, allowing it to cross the distance to Alpha Centauri in under 20 years. If the probe spacecraft does reach its objective, it will return the first-ever photographs obtained from another solar system, providing a never-before-seen insight onto faraway worlds that may or may not resemble Earth.
The ANU team described their notion in a recent research article, which is intended to make travel to Alpha Centauri a plausible option. The team is working on a small probe with a lightsail that will be driven by an Earth-based laser array. Throughout its intergalactic trip, the laser array will focus millions of beams on the sail, allowing it to attain astounding speeds.
“To span the huge distances between Alpha Centauri and our own solar system, we must think outside the box and develop a new route for interstellar space travel,” argues Dr. Bandutunga of the ANU Centre for Gravitational Astrophysics’ Applied Metrology Laboratories.
“Once launched, the sail will travel across space for 20 years before arriving at its destination. It will record photos and scientific measurements throughout its flyby of Alpha Centauri, which it will transmit back to Earth.”
100 million lasers power interstellar spaceflight
Breakthrough Starshot and the ANU team rely on the evolution of many important technologies to create their spacecraft. Lightsails, for example, has just lately been demonstrated to be a feasible mode of space travel. LightSail 2, a Carl Sagan-inspired spacecraft, successfully lifted its orbital trajectory around Earth by 3.2 kilometers in 2019 using a lightsail, or solarsail, driven by photons from the Sun.
The key hurdle, though, will be the ANU team’s cutting-edge laser array concept, which would require meticulously training millions of lasers to function in unison. “The Breakthrough Starshot initiative estimates the total necessary optical power to be roughly 100 GW — about 100 times the capacity of the world’s biggest battery today,” says Dr. Ward of the Australian National University’s Research School of Physics. “We anticipate that around 100 million lasers will be required to achieve this.”
One of the first photographs from the LightSail2 mission in 2019. The Planetary Society is the source.
To maintain their lasers aiming exactly towards the lightsail for the length of the mission, the ANU team recommends utilizing a ‘guide laser’ satellite in Earth’s orbit as a conductor, ensuring that the whole laser array is pointing at the correct coordinates. This, together with an algorithm developed to pre-correct the array’s light, will assist in account for the atmospheric distortion that the remainder of the Earth-bound lasers will experience.
Dr. Bandutunga claims that “The following stage is to begin testing some of the fundamental building elements in a controlled laboratory setting. This contains the principles of joining tiny arrays to form bigger arrays, as well as atmospheric correction techniques.” The ANU team also underlines that it is part of a worldwide partnership and that it is just focusing on one aspect of the large project.
Breakthrough Starshot is one of Yuri Milner’s Breakthrough Initiatives, a collection of scientific and technological endeavors aimed at searching for life beyond our solar system. If the lightsail prototype becomes a reality, it may be possible to achieve interstellar travel in our lifetimes by reaching the planets around our second-closest star, Alpha Centauri, which lends its star system its name.
If the initiative is successful, humans will be elevated to the high category of interstellar species. The issue is, how many more are there, if any?
