03-07-2025
A Fusion Rocket Could Soon Reach a World We Haven't Seen Since the Stone Age
Here's what you'll learn when you read this story:
In 2076, the dwarf planet Sedna will make its closest approach to the Sun in 11,400 years, and scientists are now figuring out the best way to visit the outer solar system visitor before its too late.
Although this is its 'closest' approach, Sedna will still be more than twice the distance that Sun is from Pluto, so any mission will have a plethora of challenges, including how to get there in the first place.
A new study examines the possibility of using direct fusion drives (DFD) or solar sails for such a mission, and while each have their benefits, a reliable fusion drive could deliver a 1,500 kg payload in orbit around Sedna, providing an unprecedented opportunity to learn about the furthest reaches of the Solar System.
The story of the past 35 years in astronomy has been discovering just how massive our Solar System really is. In 1992, astronomers spotted the minor planet 15760 Albion, the first object ever spotted beyond Pluto and the first official member of the Kuiper Belt. Later, at the turn of the century, astronomers (especially Mike Brown at Caltech) made a string of discoveries, including Quaoar, Maki, Makemake, Eris, and Sedna. Although these discoveries in aggregate is what eventually doomed Pluto to a planetary demotion (Eris is just a sliver smaller than pluto), Sedna was particularly eye-catching.
Roughly three times smaller than our Moon, Sedna has an extremely narrow and elliptical orbit, making its closest approach to the sun (perihelion) at roughly 76 AU—some 12.3 times closer than its aphelion at 937 AU. This makes Sedna a kind of planetary emissary to the far-flung Oort cloud. Oh, and astronomers discovered another interesting aspect about Sedna: Its closest approach was just one human lifetime away.
Fast-forward 22 years from its initial discovery and astronomers are debating how to best study this astronomical event that hasn't occurred since humans first developed agriculture during the tail end of the Stone Age. A new study, published in the online preprint server arXiv, scientists from the U.S. and Italy analyze a hypothetical mission using two distinct approaches—solar sails and direct fusion drives (DFD).
While conventional propulsion systems could require up to 30 years to perform a flyby maneuver, both solar sails and DFDs could pull off the feat in about one-third of the time. However, the outcomes of those twin missions would be vastly different because a DFD drive could actually perform an orbital insertion maneuver whereas a solar sail would be a strictly flyby mission, much like New Horizons swinging by Pluto in 2015.
'Due to the limitations of traditional methods, innovative propulsion systems are crucial to reach distant targets like Sedna,' the authors write. 'Chemical propulsion, while providing high thrust for launches, suffers from low efficiency and high fuel mass requirements for long-duration missions. Electric propulsion, including ion and Hall effect thrusters, offers much higher efficiency and finds many applications nowadays but produces insufficient thrust for rapid deep-space travel.'
A DFD, like the Princeton Field-Reversed Configuration (PFRC), would by and large be the preferred method. By the study's estimates, a fusion drive would reduce the mission time compared to conventional rockets by 50 percent while also delivering a 1500 kg payload, which is 1,000 times more than the solar sail alternative. However, this is far from a fool-proof plan. For one, fusion drives have yet to prove plasma stability and reliability during deep-space missions and that's not even beginning to consider things like communication. Secondly, while Sedna is making its 'closest' approach in 2076, it's still more than double the distance from the Sun to Pluto, meaning one-way-light-time (OWLT) would be about 13 hours—not exactly an easy environment for reliable communication.
Sending a spacecraft to Sedna would be one of the greatest challenges in the history of spaceflight, but a rewarding one. Due to its extremely strange orbit, Sedna could provide an unprecedented opportunity to learn about some of the farthest reaches of our own Solar System. Luckily, we still have a few more years to perfect a mission (especially if we go the DFD route), but scientists would need to get working sooner rather than later so that this once-in-140-lifetimes opportunity doesn't slip through our orbital grasp.
You Might Also Like
The Do's and Don'ts of Using Painter's Tape
The Best Portable BBQ Grills for Cooking Anywhere
Can a Smart Watch Prolong Your Life?
