Voyager to Dragonfly: fifty years of flying to the outer solar system

Drawn from 27 sources: NASA (20), NASA/JPL (2), The Planetary Society (2), NASA/JPL-Caltech and 2 others. About 9 minutes. Checked October 1, 2026.

Beyond Mars the Sun gives little light, distances are counted in billions of miles, and a spacecraft is designed around the decade it will spend getting there. NASA has five missions working in, or bound for, the outer solar system in October 2026. Voyager’s two spacecraft launched in 1977. New Horizons flew past Pluto in 2015. Juno has orbited Jupiter for ten years. Europa Clipper is two years into its flight to Jupiter’s moon Europa, and Dragonfly is still being wired together for Saturn’s moon Titan.

Voyager: a four-planet tour funded as a two-planet mission

The Voyager mission was designed to take advantage of a rare arrangement of the outer planets in the late 1970s and 1980s, which occurs about every 175 years and allowed a four-planet tour with a minimum of propellant and trip time. The flyby of each planet bends the spacecraft’s path and increases its velocity enough to deliver it to the next one. This “gravity assist” cut the flight time to Neptune from 30 years to 12.¹

A spacecraft that could go the whole distance was judged too expensive to build, so the Voyagers were funded to study Jupiter and Saturn only, and built to last five years. More than 10,000 trajectories were studied before choosing two; the path chosen for Voyager 2 kept the option of continuing to Uranus and Neptune.¹

After 49 years, the Voyagers’ power is running down

Earth, a speck in a sunbeam, photographed by Voyager 1 from about 3.8 billion miles away in 1990; NASA reprocessed the image in 2020.

NASA/JPL-Caltech

The two Voyagers are the only spacecraft ever to operate outside the heliosphere, the protective bubble of particles and magnetic fields generated by the Sun. Voyager 1 crossed into interstellar space on August 25, 2012, about 11 billion miles from the Sun; Voyager 2, traveling slower and in a different direction, crossed in 2018.^2,3

Voyager 1’s cameras were the first to go. On February 14, 1990, it took the images that became the Pale Blue Dot, and 34 minutes later it powered off its cameras for good, to conserve power and because neither probe would fly close enough to anything else to take pictures.⁷

Both Voyagers run on radioisotope thermoelectric generators, which turn heat from decaying plutonium into electricity, and each loses about 4 watts a year. After almost half a century, the margins are razor thin. Of the 10 instruments each spacecraft carried, seven have been shut off. On April 17, 2026, engineers turned off Voyager 1’s Low-energy Charged Particles experiment, which had run almost without interruption since 1977, after the spacecraft’s power fell unexpectedly during a routine maneuver in February. Commands to Voyager 1, more than 15 billion miles away, take about 23 hours to arrive.⁴

In the summer the team tried a more ambitious fix it called “the Big Bang”: turning off a group of powered devices all at once and replacing them with lower-power alternatives, while keeping the spacecraft warm enough to work. It succeeded on Voyager 2, which would otherwise have had to lose another instrument before the end of 2026; it should keep Voyager 2’s three remaining instruments going for at least another year. The same swap is planned for Voyager 1.^4,5

On November 18, 2026, at 2:16 a.m. Pacific time, Voyager 1 will be one light-day from Earth—16,094,799,096 miles, the distance light travels in 24 hours. No other human-made object has been that far.⁶

New Horizons: Pluto in 2015, the Kuiper Belt since

New Horizons launched on January 19, 2006, on an Atlas V. A final burn of its solid-rocket stage sent it away from Earth at about 36,400 miles per hour, the highest launch speed ever attained by a human-made object relative to Earth, and a Jupiter flyby in February 2007 cut three years off the trip. The spacecraft slept through most of the cruise, woken about two months each year.⁸

Juno: ten years at Jupiter, past its planned end

Juno arrived at Jupiter in 2016 after a five-year, 1.7-billion-mile trip, the first orbiter to look so closely beneath the planet’s clouds. From its first 53-day orbit it found unseen networks of storms around the poles, active volcanoes and lakes of lava on Io, and answers to a decades-old question about how deep Jupiter’s winds extend.¹¹

Europa Clipper: 49 passes over an ocean moon

Europa Clipper is the first mission designed for a detailed study of Jupiter’s moon Europa, where there is strong evidence of a saltwater ocean beneath the ice—possibly 40 to 100 miles deep and holding more than twice the water in all Earth’s oceans. Its main goal is to determine whether there are places below the surface that could support life.^14,15

It will not orbit Europa. Jupiter’s radiation is the most intense of any planet, and Europa lies in one of its most powerful zones, so Clipper will orbit Jupiter and dip past Europa 49 times, spending only limited periods in the worst radiation. Its electronics sit in a vault walled with aluminum-zinc plates up to 0.36 inches thick. All nine science instruments operate together on every pass.^14,15,16 NASA will invest about $5.2 billion in the mission from 2015 to the end of its prime mission in 2034.¹⁵

The rocket Congress chose, and the one it flew on

Dragonfly: a nuclear-powered rotorcraft for Titan

Titan, Saturn’s largest moon, has a nitrogen atmosphere four times denser than Earth’s and a surface coated in organic material. Dragonfly will use that atmosphere to fly. It has eight rotors and flies like a large drone; it will carry its full science payload to dozens of sites, collect surface material for analysis inside the vehicle, and look at how far the chemistry that preceded life on Earth has progressed on Titan. “Dragonfly isn’t a mission to detect life,” says principal investigator Zibi Turtle of the Johns Hopkins Applied Physics Laboratory, which is building it.^19,20

When NASA selected it in June 2019, Dragonfly was to launch in 2026 and arrive in 2034.²⁰ Then NASA had to direct the project to replan several times because of funding limits from 2020 to 2022, and the pandemic, supply-chain costs and a deeper design iteration added more. When NASA confirmed the mission in April 2024, its life-cycle cost was $3.35 billion—about twice the proposed cost—and launch was set for July 2028, more than two years late. To keep the 2034 arrival, NASA added money for a heavy-lift rocket to shorten the cruise.²¹

Launch dates that moved

The vehicle is now taking shape at APL. On June 29, 2026, the team delivered the nearly 13-foot-long flight fuselage, ahead of schedule, after a month of structural tests; integration of its mechanical, thermal and electrical systems began on July 1. By September the electrical harness—an estimated 17,315 feet of wire and 374 connectors—was being connected to instruments as they arrived. Because the rotorcraft is insulated like a thermos bottle to hold the heat of its nuclear power source in Titan’s cold, the harness had to be routed under a thick layer of foam.^22,23

The International Astronomical Union has approved a name for the dune field where Dragonfly will land: Ahmakiq Undae, about 500 miles across and bordering Selk Crater, an impact site where liquid water and complex organic material once existed together. The rotorcraft is scheduled to launch in summer 2028, reach Titan in late 2034, and work there for 3.3 years, flying every one or two Titan days—about 16 Earth days each.^19,23

What the 2027 budget request keeps

Congress protected the outer-planet missions in the 2026 budget: it gave Dragonfly $500 million, New Horizons $10 million and Juno $27.2 million after the administration had proposed ending both of the older missions.²⁴ The 2027 request again keeps the missions still in development or on their way—$424 million for Dragonfly and $160 million to operate Europa Clipper, Psyche and Lucy—but its summary does not mention New Horizons or Juno. The Planetary Society, which found that most missions marked for termination can be identified only by their absence from the request, warned that if New Horizons is switched off in the Kuiper Belt, no later saving can restore it.^25,26 Congress has not passed the 2027 bill; a continuing resolution keeps NASA at its 2026 level through December 11.²⁷

On November 18, Voyager 1 passes one light-day from Earth. Fifteen days later, on December 3, Europa Clipper swings back past Earth for the gravity assist that sends it on to Jupiter.^6,14