The probe that observed Pluto has woken up after a record-breaking hibernation
NASA’s New Horizons spacecraft, which in 2015 gave humanity its first close-up view of Pluto, has emerged from the longest ‘hibernation’ in the mission’s history. The probe spent 321 days in power-saving mode and has come out of it in good condition. It is currently approximately 9.5 billion kilometres from Earth — far beyond Pluto’s orbit.
The wake-up signal took almost 9 hours to reach Earth. It was received via NASA’s Deep Space Network and relayed to the mission control centre at the Johns Hopkins University Applied Physics Laboratory.
New Horizons will now begin transmitting the data it has collected in the outer reaches of the Solar System. It is no longer simply the ‘Pluto probe’: the spacecraft has become one of humanity’s most distant scientific outposts.
Details
New Horizons entered hibernation mode on 7 August 2025. This was neither a malfunction nor a failure, but a planned measure to conserve resources during the long flight. Such periods are necessary to reduce the strain on the spacecraft and the control team whilst the probe flies through the almost empty regions of the Solar System.
However, ‘hibernation’ does not mean that the spacecraft has been switched off completely. During this mode, the team does not usually send commands or download data, but the probe itself continues to operate according to a pre-loaded programme. NASA reported that, during its record-breaking hibernation, New Horizons continued to measure charged particles in the outer heliosphere and dust in the Kuiper Belt.
On 23 June 2026, mission controllers confirmed that the spacecraft had emerged from hibernation. According to NASA, all weekly status signals during this hibernation period were ‘green’ — meaning no problems requiring intervention were detected on board.
What it will do next
First, the team will begin to receive data on the spacecraft’s status: how its systems, power supply, communications and scientific instruments are functioning. After that, New Horizons is due to transmit the scientific data it has collected from its three instruments.
In the coming weeks, one of the instruments — the Alice ultraviolet spectrograph — will study the distribution of hydrogen in the outer heliosphere. The other instruments will continue to measure the solar wind, energetic particles and interstellar dust in the distant Kuiper Belt.
Put simply, the spacecraft is not currently studying a planet or any single specific object, but rather the environment at the edge of the Solar System: how matter travelling from the Sun behaves there, how much dust is present, and what happens in the region where the Sun’s influence gradually weakens.
Why this is important
New Horizons was launched back in January 2006. Its main target was Pluto — at that time, a virtually unexplored world on the edge of the Solar System. In July 2015, the spacecraft flew through Pluto’s system and transmitted the first detailed images and data on its moons. NASA describes New Horizons as the first – and so far the only – mission to have explored Pluto at close range.
The mission did not end there. In January 2019, New Horizons flew past Arrokoth — a small object in the Kuiper Belt. This marked the first close-up exploration of such a body in this distant region of the Solar System.
The Kuiper Belt is a region beyond Neptune’s orbit, home to icy bodies, dwarf planets and remnants of the early Solar System. NASA describes it as an area extending approximately 30 to 50 astronomical units from the Sun. New Horizons is currently operating in this distant region.
Why New Horizons has become a legendary mission
Before New Horizons, Pluto was, to science, nothing more than a small, blurred object in telescope images. Even the best images did not show its surface in detail. The spacecraft’s flyby in 2015 dramatically changed the picture: scientists saw mountains, plains, glaciers, an atmosphere and the complex geology of a world that had long been considered a virtually frozen outpost of the Solar System.
A heart-shaped region on Pluto’s surface — Sputnik Planitia — became particularly well known. But what was more important was not the ‘heart’ itself, but the overall conclusion: Pluto turned out not to be a lifeless ball of ice, but a complex and active world.
After flying past Pluto, the spacecraft continued on to the Kuiper Belt. This makes the mission particularly valuable: New Horizons found itself in a place where humanity had scarcely sent any scientific instruments before. Most spacecraft study the inner Solar System – Mars, Jupiter and Saturn – or operate close to Earth. New Horizons is one of the few probes continuing to conduct research so far from the Sun.
Why is the spacecraft being ‘put to sleep’?
New Horizons has no solar panels: they would be largely ineffective so far from the Sun. The spacecraft is powered by a radioisotope power source. This is a reliable system for deep space, but the available power gradually decreases over the years. The team must therefore plan the operation of instruments, communications and energy-saving modes very carefully.
Sleep mode helps to extend the mission’s lifespan. During this time, the spacecraft does not expend resources on a full range of operations, but retains the ability to collect important measurements and regularly report back to Earth that all is well.
In the case of New Horizons, this is particularly important: the further it travels, the longer the radio signal takes to reach Earth. At present, even a simple acknowledgement from the spacecraft takes nearly nine hours one way. Managing such a mission is increasingly less like a ‘live dialogue’ and more like sending pre-prepared instructions to a very distant point in space.