Planet 9 is an oft-discussed hypothetical planet in the outer region of the solar system. A new study involving Florida Tech astrobiologist Manasvi Lingam helps illustrate how we could possibly get there.
The study, “Can We Fly to Planet 9?” is from Lingam and researchers Adam Hibberd and Andreas Hein. The team discovered that using current, unmanned transportation methods, it would take 45 to 75 years to get to Planet 9, which is about 42 billion miles away from Earth. By comparison, Pluto, which is the ninth object from the Sun, is roughly three billion miles from Earth.
The team also studied near-future transportation methods nuclear thermal propulsion and laser sails. Using nuclear thermal propulsion, it would take approximately 40 years to reach Planet 9. It would take merely six to seven years to reach Planet 9 using laser sail propulsion, which involves using light from lasers to propel the vehicle.
Normally, when seeking more information on a planet, researchers use telescopes or send spacecraft to the planet. Planet 9 is too far for current telescopes to garner much data, so transportation methods were also examined in this work with an eye toward taking the steps necessary to learn more about the planet, such as its atmosphere (if one exists). As Lingam noted, it could be a rocky planet like Earth or a miniaturized version of Neptune. Its origin is also the subject of discussion, whether it formed initially in the solar system or was captured from elsewhere by the Sun’s gravitational pull.
In its research, the team used the principles of orbital mechanics, sometimes called spaceflight mechanics. They inputted the complex and nonlinear mathematical equations into a computer, and then solved those equations with some optimization constraints.
“What I mean by the latter is that ideally you want to maximize or minimize some quantity as much as possible,” Lingam said. “You might say, ‘Well, I want to minimize the flight time of the spacecraft as much as possible.’ So, what we did is that we put in an optimization constraint. In this case, it happens to be minimizing the time of journey. You solve the mathematical equations for a spacecraft with this condition, and then you end up with the results.”
Lingam is Inspired by the trendsetting Voyager spacecraft missions of the late 1970s, and one of his goals is to gain additional information about other worlds in our solar system, in addition to Planet 9 Voyager still provides valuable information regarding the outer solar system, though by 2025 it is expected that there may no longer be sufficient power to operate its science instruments.
“Any mission to Planet Nine would likewise not just provide valuable information about that hypothetical planet, but it would also yield vital information about Jupiter, because what we do in some of the trajectories is a slingshot or powered flyby around Jupiter,” Lingam said. “It could also provide valuable information about the Sun because we also do a maneuver around the Sun, so you would still be getting lots of interesting data along the journey. And the length of the journey is comparable to that of the functioning time of the Voyager spacecraft today.”
As this work is the first of its kind to explicitly target Planet Nine using currently available technologies, much study of the relevant subsystems (e.g., telecommunications) remains to be done.