When it comes to the challenges posed by interstellar travel, there are no easy answers. The distances are immense, the amount of energy needed to make the journey is tremendous, and the time scales involved are (no pun!) astronomical. But what if there was a way to travel between stars using ships that take advantage of natural phenomena to reach relativistic velocities (a fraction of the speed of light).
Already, scientists have identified situations where objects in our Universe are able to do this – including hypervelocity stars and meteors accelerated by supernovae explosions. Delving into this further, Harvard professors Manasvi Lingam and Abraham Loeb recently explored how interstellar spacecraft could harness the waves produced by a supernova explosion in the same way that sailing ships harness the wind.
The study that details their research, “Propulsion of Spacecrafts to Relativistic Speeds Using Natural Astrophysical Sources,” recently appeared online and was also the subject of an article at Scientific American. As they explain in their study, it is possible that a sufficiently-advanced civilization could use the blasts of energy released by supernovae to accelerate spacecraft to relativistic speeds.
These spacecraft would be able to harness the explosive force using a light sail (aka. solar sail) or a magnetic sail, two propulsion concepts that have been explored at length by astrophysicists. These concepts rely on the electromagnetic radiation generated by the Sun to create pressure against a highly-reflective sail, thus generate propulsion in a way that does not require engines or propellant.
Since propellant is one of the most significant contributors to a spacecraft’s overall mass, light sail/magnetic sail concepts have the benefit of being much lighter than conventional spacecraft – and therefore, much cheaper to launch into space. Another possibility is to rely on directed-energy (lasers) to accelerate this kind of spacecraft, allowing it to achieve speeds much higher than what would be possible with solar radiation alone.
The energy and brightness generated by a supernova are equivalent to what a billion Suns would produce in an average month. Whereas solar wind would only be able to push a light sail up to one-thousandth the speed of light (0.01% or 0.001 c), a supernova could easily accelerate a sail to one-tenth the speed of light (0.1 c).
Source: “Riding the Wave of a Supernova to Go Interstellar” Universe Today, 28 February 2020.<https://www.universetoday.com/145171/riding-the-wave-of-a-supernova-to-go-interstellar/>