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NASA / Johns Hopkins APL / Southwest Research Institute / Serge Brunier / Marc Postman / Dan Durda

NASA’s New Horizons Enters Mission’s Longest Hibernation Period (News Release)

Running with updated onboard fault protection software that improves its ability to operate farther from the Sun than originally designed, NASA’s New Horizons spacecraft has entered the longest hibernation phase of its mission.

At 4:12 a.m. EDT on August 7, flight controllers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, verified that New Horizons – acting on commands uplinked to its main computer on July 23 – had safely entered hibernation mode again. With the spacecraft now in the outer Kuiper Belt and more than 5.7 billion miles (9.2 billion kilometers) from Earth, the radio signals carrying that confirmation message from New Horizons needed 8 hours and 31 minutes – traveling at the speed of light – to reach the APL Mission Operations Center through NASA’s Goldstone Deep Space Network station in California.

New Horizons, which had been in active data-collection mode since April, will now remain in hibernation. Pending a final Fiscal Year 2026 budget, the spacecraft may be awoken in late June 2026. This will be the longest hibernation period of the mission so far, surpassing the previous mark of 273 days from June 2022 to March 2023.

But the spacecraft won’t be completely at rest; New Horizons will continue to take round-the-clock measurements of the charged-particle environment in the Sun’s outer heliosphere and the dust environment of the Kuiper Belt using three different onboard scientific instruments. These data will be transmitted back to Earth when New Horizons wakes up.

“Even when our spacecraft sleeps, round-the-clock science data collection never stops,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado.

What Is Hibernation? Hibernation is a way to extend spacecraft life and reduce mission operations costs. During hibernation, New Horizons remains in a stable spinning mode with much of the spacecraft unpowered. The onboard flight computer monitors system health and broadcasts a weekly beacon-status tone back to Earth through NASA’s Deep Space Network of communications and tracking ground stations.

Since 2007, New Horizons has hibernated 23 times, for periods ranging from just days to many months.

The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, designed, built and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate and the mission’s principal investigator. Southwest Research Institute, based in San Antonio, directs the mission via Principal Investigator Alan Stern, who leads the mission for NASA. NASA Marshall Space Flight Center’s Planetary Management Office in Huntsville, Alabama, provides NASA oversight for New Horizons.

Source: NASA.Gov