From Earth to Uranus: How Long Would it Take to Reach the Ice Giant?
Last Updated: August 29, 2023
When considering the planets, Uranus mostly fades to the background except perhaps for a chuckle at its modern pronunciation or questions regarding how it ended up on its side. When we consider nearby bodies in space, we often wonder and dream about visiting them.
But, how long would it take to get there? Let’s dive into the various factors to determine how long it would take to travel to Uranus!
The basics of space travel
When calculating travel time you use two basic measurements: the distance and the speed of the vehicle. The average distance between Earth and Uranus is 1.8 billion miles (2.9 billion kilometers), ranging from 1.6 billion miles (2.6 billion kilometers) at their closest to 1.98 billion miles (3.2 billion km) at their farthest. It’s so far away (19.8x further from the Sun than Earth) that it was only discovered in 1781 by William Herschel, making it the first planet to be discovered with a telescope as it cannot be seen with the naked eye (unless you have 20/20 vision and know EXACTLY where to look). However, just as it is here on Earth, travel time highly depends on the route you take.
Related Article: How Far Away Is Uranus From Earth Right Now?
There are typically four factors when considering a more precise flight duration to any astronomical object:
- Whether or not the spacecraft is sent to other celestial objects either for scientific studies and/or a gravity assist using a slingshot flight maneuver. While a quick flyby mainly for a gravity assist will dramatically increase speed and decrease travel time, time spent studying that planetary system becomes a little more complicated in terms of its actual impact on average velocity and travel time.
- The launch vehicle capabilities as much of the speed of the aircraft (disregarding gravity assists and thruster adjustments) will be determined by the speed the rocket can attain after escaping Earth’s gravity, which requires a minimum of 7 miles/ 11.2 kilometers per second (25,000 mph or just over 40,000 km/ hr) just to reach Earth’s escape velocity. As a baseline, the Apollo spacecraft reached a speed of 8 km/sec.
- Slowing down requires time by either reverse-firing thrusters in space or utilizing atmospheric re-entry if landing. A flyby will be shorter than an orbit insertion (which is the best we can do for Uranus since we can’t land on it since there is no surface) or landing on the surface of an object like a moon.
- A planet is not a fixed point in space like a house since it is constantly moving around the Sun. So, we can’t only plan to reach the end destination based on the distance when we launch, but where it will be by the time we reach it. This calculation also has to be done for any gravity assists that will be planned along the trip.
While theoretical flight plans are helpful, what real flight plans can we compare to better understand more realistic travel times to Uranus?
Past missions to Uranus
Only one spacecraft has visited Uranus: Voyager 2. The Voyager spacecraft (1 and 2) were created to perform a “Grand Tour of the Outer Solar System”. Due to budget and other concerns, the missions were whittled down, but still took advantage of a rare planetary alignment to study the outer solar system before heading into interstellar space. Both carried a copy of the Golden Record, a 12-inch/ 30 centimeter diameter gold-plated copper disc that contained a message from humanity to space including examples of life on Earth, greetings, and music as well as instructions on how to play the samples.
Both spacecraft weighed 1,592 pounds (721.9 kilograms) and were launched on top of a Titan IIIE-Centaur rocket. This rocket system was also used to launch the Viking probes and the Helios spacecraft. Voyager 1’s mission focused on studying Jupiter and Saturn before launching toward interstellar space while Voyager 2 completed more of the Grand Tour of the Outer Solar System originally proposed for the project, targeting Jupiter, Saturn, Uranus, and Netprune before launching into interstellar space.
Despite being named Voyager 2, it actually launched earlier on August 20, 1977, versus Voyager 1’s launch date of September 5th, 1977, and is still the only spacecraft to have studied all four of our solar system’s gas giants at close range.
Mission Log of Relevant Key Dates for Voyager 2:
|August 20, 1977||Launch|
|December 15, 1977||Passed by Voyager 1||Meaning Voyager 1 actually exited the asteroid belt earlier|
|April 24, 1979||Began transmitting images of Jupiter, and made close passes to the Jovian moons|
|July 9, 1979||Jupiter flyby and gravity assist and course correction 2 hours later||Closest approach at a range of about 400,785 miles (645,000 kilometers)|
|Aug. 22, 1981||Imaged the moon Iapetus, beginning its encounters with Saturn’s system|
|Aug. 26, 1981||Saturn flyby closest approach at a range of about 63,000 miles (101,000 kilometers)||Photographed Hyperion, Enceladus, Tethys, Phoebe, Helene, Telesto, and Calypso (the last three were only recently discovered).|
|Summer 1982||Course correction to Uranus|
|Nov. 4, 1985||Long-range observations of Uranus begin|
|Jan. 24, 1986||Uranus flyby closest approach at a range of about 50,640 miles (81,500 kilometers) with only 5.5 hours of close study during its flyby||discovered 10 new moons (Puck, Portia, Juliet, Cressida, Rosalind, Belinda, Desdemona, Cordelia, Ophelia, and Bianca), two new rings to add to the older nine rings, and its tilted magnetic field|
|Feb. 14, 1986||Mid-course correction, the largest made by the spacecraft to send it toward Neptune|
|Aug. 25, 1989||Neptune flyby closest approach, flew about 2,980 miles (4,800 kilometers) over the cloud tops of the giant planet, the closest of its four flybys||discovered six new moons (Proteus, Larissa, Despina, Galatea, Thalassa, and Naiad) and four new rings|
|November 1998||Nonessential instruments were permanently turned off, leaving seven instruments still operating|
|Dec. 10, 2018||Entered interstellar space|
|July 8, 2019||Voyager 2 successfully fired its trajectory correction maneuver thrusters, continued to return data from five instruments|
The Voyager spacecraft reached a speed of 17 km/ sec with the aid of gravity assists
So, launch to flyby of Uranus was from Aug. 20, 1977 to Jan. 24, 1986 (eight years, five months) for Voyager 2, but it’s important to remember that it included a gravity assist from Jupiter and a unique line-up of planets that helped to greatly reduce the travel time to each planet.
Related Article: How Much of Space Have We Explored So Far?
Other missions that did not go to Uranus but have tangential Uranus data
NASA briefly considered sending Cassini (the spacecraft that studied Saturn) to Uranus after its primary mission was completed. Travel time from Saturn to Uranus was calculated at a decade. Instead, its primary mission of studying the ringed planet and its moons was extended until its planned plummet into the planet’s atmosphere.
The New Horizons spacecraft’s mission is focused on the dwarf planet Pluto, its moons, and the Kuiper Belt, an icy asteroid belt past Neptune. It is often cited in estimations of space travel because it’s one of the most recent and therefore most advanced propulsion systems, particularly when considering travel to the outer solar system.
The New Horizons spacecraft weighed 1,054 pounds (478 kilograms) and utilized the Atlas V 551 launch vehicle. New Horizons launched on January 19, 2006, and after reaching initial Earth orbit, accelerated the spacecraft to a velocity of about 10.1 miles per second (16.26 km/ s) or 36,400 miles per hour (58,536 kilometers per hour), the highest launch velocity attained by a human-made object relative to Earth. It crossed the orbit of Uranus on March 18th, 2011 while it was in hibernation mode to get to Pluto as quickly and efficiently as possible. Remember that this 5-year trip is not accurate because it did not stop at Uranus which would require extensive maneuvers over the course of months (7 months from approach phase to close approach of Pluto).
Future Missions to Uranus
Missions to Uranus have been proposed over the years, but often tabled in favor of other missions that are deemed of higher scientific value. When planning a mission to the outer solar system, finding an ideal window can take up to a century since Uranus orbits the Sun once every 84 Earth years.
The Uranus Orbiter and Probe is a proposed joint NASA and ESA mission to study Uranus, including deploying a probe into its atmosphere to gather data. Experts estimate the trip to take 12-15 years, primarily depending on the launch date which would determine the distance between the two planets.
The original proposed flight plan listed a launch date of 2031 or 2032 utilizing a Falcon Heavy expendable launch vehicle which would take 13.4 years to reach Uranus (in 2044 or 2045) utilizing a gravity assist from Jupiter, after which it would study the mysterious planet and its moons for a primary mission of 4.5 years (potentially open for an extension or secondary mission depending on the state of the craft). The end of the ideal launch window is 2038, which would necessitate a 15-year journey due to the position of Uranus. NASA has just recently (2023) pushed the launch back due to a decrease in plutonium production, meaning a mid-to-late 2030s launch is more likely.
If we could reach Uranus by 2049, we have the chance to have the most contrast with Voyager 2’s data during the planet’s southern hemisphere’s summer, if it can arrive before southern spring begins in 2049.
Parker Solar Probe
The Parker Solar Probe currently holds the record for the fastest spacecraft at 364,745 mph 587,000 km/hr in 2021. Theoretically, at its 2021 speed, Parker could reach Uranus in about 206 days, but part of the reason Parker’s speed is so high is that it is falling into the Sun’s gravity versus trying to escape it so this speed wouldn’t actually be achievable on a trip to Uranus.
None of these missions has human occupants. We need to go slower to accommodate our fragile bodies. In fact, the fastest that humans have ever traveled in space is 24,791 mph (39,897 km/ hr), which was achieved by the returning Apollo 10 astronauts in May 1969.
It takes an average of 6 hours to three days for astronauts to travel on a Soyuz rocket to the International Space Station which sits at an altitude of about 253 miles (408 km). However, SpaceX launches to the ISS currently average 24 hours with the SpaceX Crew-4 mission in May of 2022, clocking in at less than 16 hours.
The new NASA SLS system designed to bring humans back to the moon has a top speed of over 6 miles/9.7 km per second which roughly equates to over 21,600 mph or 34,920 km/hr, but that may change as the missions continue to develop and as technology continues to improve in both engines and protecting the human body.
A spacecraft with humans onboard would likely take 14-17 years to reach Uranus in the near future (considering the distances between the two planets). It is important to remember that the ongoing and upcoming missions to return humans to the moon also prepares us to go to Mars by the 2040s. These future missions will help us adapt and innovate to further innovate human exploration of the solar system.
Theoretical Light Speed
Uranus sits at about 1.8 billion miles (2.9 billion kilometers) away The calculation is highly dependent on the speed achieved, the route, the number of “stops”, the number of gravity assists, and the approach procedure in which we slow down. Do we go straight to Jupiter or utilize gravity-assist maneuvers from other planets, especially to save on fuel?
Based on previous and planned upcoming spacecraft missions to Uranus, it would likely take 12-15 years for a probe to travel that distance, at least factoring in a launch in the next decade or so. For humans, it would likely take closer to 14-17 years to safely travel there due to what our bodies can withstand, but that number will likely decrease due to innovations by the time we are actually considering sending a human to the pale blue seventh planet or one of its moons.
If one thing is clear from calculating the time it would take to get to Uranus, it is that human ingenuity allows us to accomplish amazing feats and surpass even what were once our greatest achievements. Even within the next decade or two, this timetable could be very different depending on the current state of technology, and that is the beauty of scientific progress.
Sarah Hoffschwelle is a freelance writer who covers a combination of topics including astronomy, general science and STEM, self-development, art, and societal commentary. In the past, Sarah worked in educational nonprofits providing free-choice learning experiences for audiences ages 2-99. As a lifelong space nerd, she loves sharing the universe with others through her words. She currently writes on Medium at https://medium.com/@sarah-marie and authors self-help and children’s books.