00:00Humanity is preparing to push past the edge of our solar system.
00:05In the coming decades, we plan to send advanced probes, and eventually human crews, deep into interstellar space.
00:14But right now, we have a critical vulnerability.
00:17Every spacecraft we launch is entirely tethered to Earth-bound communication networks.
00:23This is a facility in the Deep Space Network, a system of massive radio dishes we use to track our
00:31explorers from the ground.
00:32The physics of this system create a severe bottleneck.
00:37As a spacecraft travels further into the vast, dark expanse, Earth's tracking signals become weaker and suffer massive time delays.
00:47Relying on this fragile tether could prove catastrophic for long-range missions.
00:52A multi-hour delay in navigation data might mean missing an orbital insertion or colliding with a hazard.
01:00To survive out there, a spacecraft needs an autonomous on-board compass.
01:06Fortunately, the universe itself provides a vast, built-in navigation network forged from the glowing corpses of dead stars.
01:16Exploring the deep cosmos requires us to look past our Earth-made maps and learn to read the navigational beacons
01:24forged by the galaxy itself.
01:26These beacons begin with a massive, ancient star at the very end of its life cycle, burning through its final
01:34reserves of nuclear fuel.
01:36The outward pressure of nuclear fusion is the only force holding the star's immense mass against its own gravity.
01:45The moment that fuel runs out, the pressure vanishes, and gravity instantly crushes the star inward.
01:52The collapsing material hits the dense center and rebounds, exploding outward in a supernova.
02:00As we see in this image of a supernova remnant, the event violently obliterates the star's outer layers and sends
02:08massive shock waves across space.
02:10Amidst this expanding explosion, a microscopic remnant remains at the exact center.
02:17This crushed core is compacted into a hyper-dense sphere, barely the size of a city, known as a neutron
02:25star.
02:26The violent destruction of the parent star acts as the manufacturing process required to forge one of the universe's most
02:34extreme physical objects.
02:36When the stellar core collapses, it retains its rotational energy.
02:41As it shrinks, its speed skyrockets.
02:44It now completes hundreds of rotations per second, generating intense magnetic fields.
02:50These poles shoot concentrated beams of radiation, which sweep in a wide arc as it spins.
02:57From our perspective, this creates a distinct pattern.
03:00Whenever those sweeping beams cross our line of sight, our telescopes detect a rhythmic flashing.
03:07We call this a pulsar.
03:09The death of a massive star creates this pulsar, transforming a stellar corpse into a precise cosmic lighthouse.
03:17Because these pulsars spin in the frictionless vacuum of space, their momentum is unobstructed.
03:23Their rhythmic flashing remains stable over millions of years.
03:27This stability rivals our most advanced human-made timekeepers.
03:32Pulsar rhythms often match or even exceed the long-term accuracy of the complex atomic clock shown here.
03:39NASA is preparing to harness this precision through the Sexton project.
03:43Future spacecraft will carry specialized X-ray detectors designed to simultaneously read the unique flash rates of multiple different pulsars.
03:50By cross-referencing these distinct flashes, the spacecraft's onboard computer can triangulate its exact coordinates anywhere in the galaxy,
03:58operating independently of the deep space network on Earth.
04:01A star's journey, from a silent dust cloud to a spinning beacon, provides the map humanity needs to explore the
04:07dark universe.
04:08To continue exploring the cosmos' greatest mysteries, subscribe to Lighthouse Galaxy.
04:12And to see the actual X-ray hardware being built for this mission, click the video on your screen right
04:17now.
