Theoretical physicist suggests radical plan to slow interstellar spacecraft

20 Nov 2017

Concept image of a spacecraft in deep space. Image: Vadim Sadovski/Shutterstock

While it takes a considerable effort just to launch an interstellar spacecraft, engineers are now trying to solve the issue of getting them to slow down.

The recent documentary The Farthest showcased the incredible decades-long journey of the Voyager 1 and Voyager 2 spacecraft as they ventured into interstellar space, where they will continue on forever.

This infinite journey was not an engineering choice, but a matter of physics. This begs the question: would it be possible to slow down future spacecraft, such as the Breakthrough Starshot project, from barrelling endlessly into space?

The aforementioned project is one of the most ambitious spacefaring missions to date, with plans to send a number of tiny spacecraft (the size of an iPhone) to our next-nearest star, Alpha Centauri, in just 20 years.

Just like Voyager 1 and 2, these spacecraft will speed on endlessly once their mission is completed, despite a scientific interest to slow them down in the star system to gather even greater amounts of data.

Slow by astronomical terms

In a paper published to the Journal of Physics Communications, a theoretical physicist from Goethe University Frankfurt called Prof Claudius Gros has proposed a solution that would use magnetic sails to help slow the craft down.

The sail would stretch 50km in diameter and would consist of a large, superconducting loop.

A lossless current induced in this loop would create a strong magnetic field as the ionised hydrogen in the interstellar medium would be reflected off the probe’s magnetic field, slowing it down gradually.

“Slow would mean, in this case, a travel velocity of 1,000km per second, which is only 0.3pc of the speed of light but nevertheless about 50 times faster than the Voyager spacecraft,” Gros explained.

Having shown formulae demonstrating its slowing ability in space, Gros’ magnetic sails would work on spacecraft with a weight of up to 1,500kg.

The problem is, however, that this would drastically increase the travel time, such as in the case of the TRAPPIST-1 system, where a craft would take 12,000 years to get there.

A possible use could be in a project Gros proposed, which would carry single-celled organisms – either as deep-frozen spores or encoded in a miniaturised gene laboratory – into deep space.

Colm Gorey was a senior journalist with Silicon Republic