00:00Imagine waking up adrift in a pitch black void.
00:04There is no up, no down, no magnetic north to guide a compass,
00:09and absolutely zero standard GPS signals to tell you where you are.
00:15To find our way across the deep cosmos,
00:17we will not rely on a network of orbiting man-made satellites.
00:22Instead, we are going to navigate using the crushed, spinning corpses of dead stars.
00:29Welcome to Lighthouse Galaxy.
00:32Today, we are looking at the massive engineering hurdle of leaving Earth's radio signals behind,
00:38and how we are building a system of cosmic navigation.
00:42Interstellar exploration requires us to swap our Earth-bound coordinates
00:47for a frame of reference that covers the entire galaxy.
00:51Right now, every spacecraft humanity has ever launched operates on a very long, invisible leech.
00:58They are entirely dependent on Earth to know where they are.
01:02This image displays the tracking data for the deep space network.
01:07Giant antennas located in Madrid, Goldstone, and Canberra ping radio waves out to our distant probes,
01:14and then Mission Control waits for a response to calculate the probe's exact coordinates.
01:20The limit of this system is that radio waves obey the universal speed limit.
01:25They can only travel at the speed of light,
01:28which creates a massive communication lag the further out a probe travels.
01:33If Mission Control wants to find the exact location of a spacecraft passing Pluto,
01:38a single navigation ping takes four hours just to arrive, and another four hours to return.
01:45At just one percent of light speed, a spacecraft travels over a million miles in eight hours.
01:52By the time Earth calculates a position and beams a correction back,
01:56the ship is already hundreds of thousands of miles off course.
02:00Deep space vehicles need a way to navigate in real time, independently.
02:05The solution to this navigation problem begins with the death of a massive star.
02:11When a giant star goes supernova, it blows away its outer layers
02:16and leaves behind a hyper-dense core known as a neutron star.
02:20These neutron stars, called pulsars, spin hundreds of times per second.
02:26Their magnetic fields guide tight beams of X-ray radiation from their poles.
02:32Because of this spin, those beams sweep the cosmos,
02:36appearing to Earth as a perfectly rhythmic flash, like a lighthouse.
02:40This stellar death produces a cosmic metronome.
02:44The flashes arrive with such precision,
02:46they act as the most reliable timekeeping mechanisms in the known universe.
02:52Space navigation is ultimately just the precise measurement of time delays.
02:57Your smartphone map measures the arrival times of radio signals from multiple satellites.
03:02By calculating how long each signal takes, it triangulates your position at the intersection.
03:09X-ray pulsar-based navigation, or XNAV, applies this exact triangulation logic to the galactic level.
03:16Instead of receiving pings from Earth's satellites,
03:20a spacecraft equipped with an onboard X-ray telescope
03:23monitors the arrival times of flashes from three or four different pulsars simultaneously.
03:30Because the rhythm of those pulsar flashes is as reliable as an atomic clock,
03:35calculating the intersection of their signals
03:38transforms the dark void of the galaxy into a mathematically readable three-dimensional map.
03:44This is an actively tested and mathematically proven navigation protocol.
03:49In 2017, NASA launched the Nicer Sextant experiment.
03:54An instrument observed pulsar flashes and used their timing to autonomously calculate its own location in space.
04:01That experiment took place on the exterior of the International Space Station,
04:06tracking dead stars while traveling 17,000 miles per hour in low Earth orbit.
04:11Mastering XNAV removes the need for Earth-based radio dishes.
04:16A ship equipped with an X-ray receiver can plot its own path across the Mokiway,
04:22making autonomous travel to other star systems a functional reality.
04:26To find our way to new star systems,
04:30we will navigate by the crushed remains of ancient ones.
04:34Subscribe to Lighthouse Galaxy to continue exploring the hidden pathways of the cosmos,
04:39and click the video on screen to see what happens when a star dies.
04:44SONY
Comments