A groundbreaking mission that explored Pluto and distant solar system objects in unprecedented detail has awakened from its longest sleep ever — and it’s 5.9 billion miles (9.5 billion kilometers) from Earth.
NASA’s New Horizons spacecraft went into a planned hibernation mode on August 7, 2025, and woke up on June 23 using commands stored on its main computer.
The mission’s flight controllers at the Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, confirmed that New Horizons is in great shape and ready to transmit a stream of science data gathered during hibernation from its location in the region of icy objects known as the Kuiper Belt.
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Pluto is the largest of thousands of frozen, rocky bodies called trans-Neptunian objects, or TNOs, that exist in the Kuiper Belt at the edge of our solar system — remnants from its formation 4.5 billion years ago.
In 2015, New Horizons became the first spacecraft to conduct a detailed flyby of Pluto and its moons, which changed scientists’ understanding of the frigid dwarf planet. The spacecraft also carried out an up-close examination of Arrokoth, a snowman-shaped TNO, in 2019.
Since these milestones, New Horizons has continued exploring the mysterious Kuiper Belt — and it’s uncovering surprising revelations.
The spacecraft is capturing data about the rotation rates, orientations and shapes of frozen objects that orbit in the Kuiper Belt.
The measurements provide insights into how planets are born from dust and pebbles, said Pontus Brandt, New Horizons project scientist at the Johns Hopkins Applied Physics Laboratory.
“There seems to be more paired, snowman-shaped bodies, like Arrokoth, out there than anyone expected,” Brandt wrote in an email. “Are such binaries the most common planetesimal and is this how larger planets have been built in our own and other stellar systems? These are very deep questions that New Horizons can help answer.”
The spacecraft also measures the distribution of gas in the outer heliosphere, the expansive, protective bubble formed by a steady stream of particles that release from the sun called the solar wind.
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Meanwhile, an instrument called the Pluto Energetic Particle Spectrometer Science Investigation is measuring galactic cosmic rays, extremely fast particles created when stars explode. The particles pose one of the more severe threats for human activities in space, Brandt said, but the boundary of the heliosphere acts as a shield to protect our solar system from 70% of them. New Horizons’ data could help scientists learn more about how this puzzling shielding works, he said.
Another instrument, the Venetia Burney Student Dust Counter, has collected data that has thrown New Horizon’s team a curveball, Brandt said. The team expected dust abundance to be high within the Kuiper Belt due to the significant presence of small objects. But New Horizons has traveled beyond the known boundary of the Kuiper Belt — and it’s still in a dusty environment.
“The Kuiper Belt could simply be much more extended than what we previously have thought,” Brandt wrote. “I have a hunch that we have just scratched the surface of what the entire solar system really looks like.
We have to remember that there are likely 100’s of unexplored dwarf planets and 1000’s of smaller objects out there.”
The Nancy Grace Roman Space Telescope, expected to launch at the end of August, can use its powerful observational tools to see what exists beyond the Kuiper Belt, Brandt added.
Hibernation periods have been the key to New Horizons’ long-lived success since it launched and embarked on its trek across the solar system in January 2006.
During these sleep periods, New Horizons remains in a largely unpowered but stable mode, while its flight computer keeps close tabs on the spacecraft’s condition and sends back a weekly beacon to flight controllers.
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“Every status report through this hibernation period was ‘green,’ meaning all was well aboard New Horizons each and every week,” Alice Bowman, the New Horizons mission operations manager at the Applied Physics Laboratory, said in a statement.
Meanwhile, the instruments continue collecting and storing data to send back once New Horizons is awake again.
Hibernations extend the spacecraft’s lifespan and conserve resources during long cruises. New Horizons has hibernated more than 20 times since 2007, sometimes for days or even months, according to NASA.
New Horizons is in its second continued mission, which concludes in 2029, but the mission could go on if the spacecraft is healthy and can collect valuable science data, according to Becky McCauley Rench, New Horizons program scientist at NASA.
If the mission lasts beyond 2029, New Horizons may follow in the historic steps of the Voyager probes as the spacecraft’s current trajectory will take it outside the heliosphere and into interstellar space.
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