According to an Australian National University (ANU) press release, it will have to create and test a new kind of spacecraft propulsion system that employs a lightsail and a laser beam array to attain the huge speeds required for interstellar travel within our lifetimes.
Breakthrough Starshot’s ultra-lightweight spacecraft will have to travel four light-years to reach Alpha Centauri. To put it another way, the closest star system to Earth is 40,208,000,000,000 (40 trillion) kilometers away.
In contrast, the ion thruster, which is pushing NASA’s DART mission to a nearby asteroid at speeds of 15,000 mph (24,000 km/h), is the quickest and most reliable long-distance space travel technology available today. However, NASA believes that reaching Alpha Centauri with an ion thruster would take 18,000 years or about 2,700 human generations.
With the use of lasers deployed on Earth, the Breakthrough Starshot team hopes that its spaceship will be able to reach incredible speeds, enabling it to travel to Alpha Centauri in under 20 years. If the probe spacecraft succeeds in reaching its goal, it will return the first-ever images taken from another solar system, delivering a never-before-seen look at distant planets that may or may not resemble Earth.
In a recent research publication, the ANU team presented their idea, which is meant to make travel to Alpha Centauri a viable possibility. The team is developing a tiny probe with a lightsail that will be powered by a laser array on Earth. The laser array will concentrate millions of beams on the sail during its interplanetary journey, enabling it to reach incredible speeds.
“We need to think outside the box and design a new path for interstellar space travel to cover the enormous distances between Alpha Centauri and our own solar system,” says Dr. Bandutunga of the ANU Centre for Gravitational Astrophysics’ Applied Metrology Laboratories.
“The sail will travel for 20 years across space once launched before reaching at its destination. During its flyby of Alpha Centauri, it will take images and take scientific measurements, which it will broadcast back to Earth.”
Interstellar spacecraft is powered by 100 million lasers.
Breakthrough To build their spaceship, Starshot and the ANU team depends on the progress of a number of key technologies. Lightsails, for example, were just recently shown to be a viable form of space travel. Using a lightsail, or solarsail, powered by photons from the Sun, LightSail 2, a Carl Sagan-inspired spacecraft, successfully boosted its orbital trajectory around Earth by 3.2 kilometers in 2019.
The ANU team’s cutting-edge laser array idea, which would need methodically training millions of lasers to work in harmony, would be the major stumbling block. According to Dr. Ward of the Australian National University’s Research School of Physics, “the total required optical power is estimated to be over 100 GW — nearly 100 times the capacity of the world’s largest battery today.” “We estimate it will take roughly 100 million lasers to do this.”
One of the first images from the 2019 LightSail2 mission. The source is the Planetary Society.
The ANU team advises using a ‘guide laser’ satellite in Earth’s orbit as a conductor to keep their lasers aimed precisely towards the lightsail for the duration of the mission. This will ensure that the whole laser array is directed at the proper coordinates. This, in combination with an algorithm created to pre-correct the array’s light, will help accommodate for the atmospheric distortion that the remaining Earth-bound lasers will face.
According to Dr. Bandutunga, “The next step is to start testing some of the basic building components in a controlled laboratory environment. The basics of combining small arrays to construct larger arrays, as well as atmospheric correction methods, are covered in this chapter.” The ANU team also emphasizes that it is a member of a global collaboration and that it is just working on one facet of a larger undertaking.
Breakthrough Starshot is one of Yuri Milner’s Breakthrough Initiatives, a group of scientific and technology projects aiming at finding life outside of our solar system. If the lightsail prototype becomes a reality, we may be able to reach the planets around our second-closest star, Alpha Centauri, which gives its star system its name, within our lifetimes.
Humans will be promoted to the high category of interstellar species if the proposal succeeds. The question is, how many more, if any, are there?