JUNE 1, 2022
Interstellar travel has been the dream of humankind ever since some distant ape-person looked up at the stars and wondered if there was any way off this rock. The idea of being to sustainably travel off-planet and between solar systems has been a constant in science fiction, whether as the core conceit (as in the 1997 movie Contact, based on a story by Carl Sagan and Ann Druyan in which aliens look like David Morse) or as a plot device (ie, all of the Star Trek franchise). Give or take the occasional Stargate, a consistent thread in all these stories about interstellar travel is the usage of spaceships to transport humans across the cosmic gulf. However, Professor Irina K. Romanovskaya has another idea: hopping rogue planets.
In a paper first published in the International Journal of Astrobiology, titled “Migrating extraterrestrial civilizations and interstellar colonization: implications for SETI and SETA,” Professor Romanovskaya posits the usage of rogue planets for interstellar travel. To put it simply, rogue planets are physical masses the size of planets that have either been ejected from a solar system due to gravitational events (or possibly for being overserved) or that coalesced independently. Recently, more and more rogue planets are being discovered, with some scientists estimating there may be more than 50 billion in our galaxy alone. So what do they have to do with interstellar travel?
Basically, these rogue planets are already on their own free-floating interstellar travels. The idea that Professor Romanovskaya is posing is that it is theoretically possible for a sufficiently advanced civilization to essentially commandeer one of these objects and use them to get off the planet. While the many rogue planets (insofar as they have been observed to any significant degree) are barren and essentially huge wandering asteroids incapable of sustaining human life, Professor Romanovskaya goes on to theorize that some may contain surface and subsurface oceans. Along with a sustainable atmosphere and a dependable gravitational force, this could make this a useful resource for interstellar travel.
As with any discussion of interstellar travel, Professor Romanovskaya’s theory of rogue planet-hopping is very much a theory dependent on a multitude of factors. Aside from the necessity of a rogue planet that has the necessary water for sustainable human existence, there would also have to be one of these roaming planets that gets close enough to our solar system to make it feasible to get on board. Then there would be the question of if a rogue planet could be steered in some fashion (utilizing solar sails, for example, a technology that is also largely theoretical) or if humans on board would just be hoping this planet knows where it’s going.
Professor Romanovskaya is certainly not positing that utilizing a rogue planet for interstellar travel is anything remotely possible given our current level of technology as a species. Her paper is largely devoted to conceptualizing it as a possibility and raises the idea of an (also theoretical) advanced alien civilization using this method of non-spaceship travel. This is all well and good, but we’ll keep dreaming of our Millenium Falcons for now.