NASA's New Horizons wakes from yearlong hibernation to study interstellar boundary

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There's nothing more disorienting than falling asleep in transit only to wake up and find you've somehow drifted billions of miles beyond the orbit of Pluto .

Fortunately for NASA's New Horizon spacecraft, which scientists just awakened from a nearly yearlong hibernation at the solar system's edge, all systems are in "good health," according to a NASA statement . Now, with the probe recovered from its 321-day sleep and beginning to transmit science data again, New Horizons appears ready to continue its mission of studying the mysterious boundary where the sun's realm ends and interstellar space begins.

"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 Johns Hopkins Applied Physics Laboratory in Maryland, said in the statement.

New Horizons launched in 2006, breaking the record for fastest-ever space launch at roughly 36,400 mph (58,500 km/h). On its way to the edge of the solar system , the spacecraft picked up speed during a flyby of Jupiter in 2007 and then again while passing Pluto in 2015. Today, New Horizons is about 5.9 billion miles (9.5 billion kilometers) from Earth, or roughly 64 times the distance from Earth to the sun (64 astronomical units, or AU).

With the exception of the twin Voyager probes that launched in 1977, New Horizons is the farthest working spacecraft in the universe. (Two other probes, Pioneer 10 and 11, have traveled farther, but each stopped working several decades ago.)

An illustration of the Kuiper Belt object Arrokoth, the farthest-ever solar system object to receive a close flyby. New Horizons whizzed past it in 2019. (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Steve Gribben) Like the Voyager twins, New Horizons is on a trajectory toward the heliopause — the extreme outer edge of the sun's influence, where solar wind collides with the interstellar medium.

The Voyager probes proved that this dividing line is a measurable, physical boundary in space, marked by a hot, thick plasma barrier . However, New Horizons will eventually pass this boundary with far more sensitive instruments than the Voyagers held, enabling it to collect the most detailed data about this region ever.

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But there's still a long way to go. The heliopause is estimated to begin about 120 AU from the sun — nearly twice as far as New Horizons has traveled so far. In the meantime, a long and lonely journey through the Kuiper Belt awaits. In the coming weeks, the spacecraft will begin conducting a study of hydrogen in the outer reaches of the heliosphere as it sends back the hoarded trove of data from its year in hibernation.

According to NASA, each transmission between New Horizons and Earth takes about 8 hours and 52 minutes, with that delay growing all the time.

In the Kuiper Belt, New Horizons may also have the chance to study peculiar, icy objects similar to the peanut-shaped space rock Arrokoth , which the probe flew by in 2019. This was the furthest object in the solar system ever to receive a close spacecraft flyby; whether New Horizons will break its own record again in the coming years is an open question.