Voyager 1 will reach one light-day from Earth in 2026. Here’s what that means

CNN Voyager NASA s deep-space probe could soon become the first spacecraft to reach a historic milestone In November the probe will be one light-day from Earth Launched in Voyager is the farthest spacecraft from our planet at this moment exploring interstellar space billion miles away The term light-day refers to the distance at which it will take hours for a signal or command traveling at the speed of light to reach the spacecraft from Earth mentioned Suzy Dodd Voyager project manager at NASA s Jet Propulsion Laboratory One light-day is equivalent to billion miles billion kilometers So if Voyager s band is asking the spacecraft to do something once it reaches that point it will take another day for Voyager to respond If I send a command and say good morning Voyager at a m on a Monday morning I m going to get Voyager s response back to me on Wednesday morning at approximately a m Dodd stated Voyager and its twin Voyager are the only spacecraft to operate beyond the heliosphere the sun s bubble of magnetic fields and particles that extends well beyond the orbit of Pluto After decades in space both have had to turn off several instruments but they are using their remaining tools to survey this uncharted territory and provide content that could inform future missions There are a multitude of challenges that come with staying in communication with such far-reaching probes but Dodd and her squad are taking necessary attempts to ensure that their senior citizens reach their th anniversary in Staying in touch over cosmic distances Launched on a journey to explore Jupiter and Saturn Voyager has been traveling away from Earth on the same trajectory and at the same speed miles per hour since its flyby of Saturn in November With an understanding of Earth s location relative to Voyager the spacecraft s speed and its trajectory engineers are able to calculate how long it takes a signal to reach the probe For example Voyager s trajectory after the Saturn flyby took it up and out of the plane of the planets after it passed Saturn while Voyager passed over the top of Neptune after its flyby of the ice giant and moved down and out of the plane of the planets Neither probe has had a trajectory adjustment since their last planetary flybys meaning that both have been on decades-long uninterrupted cruises Voyager isn t expected to reach one light-day from Earth until November and even the most of ambitious estimates suggest the spacecraft won t be operating then But both probes keep surprising the group Every day as the oldest functioning spacecraft the Voyager probes hold a record just by continuing to operate But it hasn t been an easy process The probes send back statistics at a very low bits per second or a material rate similar to dial-up internet Dodd explained The distance that we are away from the Earth takes much longer to get a signal there and the signal strength just dissipates Dodd noted It takes multiple antenna arrays to gather that signal back The low evidence rate means that Dodd and her group receive sparse information about the robustness of each spacecraft and if there is an issue they aren t able to respond fleetly However both Voyagers are designed to be self-sufficient with plenty of onboard autonomy so they can save themselves if things go sideways billions of miles from Earth If they get something going wrong they can put themselves in a safe state so that they can wait until we re able to talk to the spacecraft and figure out what the trouble is and resolve that issue Dodd noted Why the Voyager probes endure For years the company has made tough decisions to ensure the probes operate for as long as realizable Dodd reported That means turning off engineering systems and instruments to conserve power and ensuring that the spacecraft remains warm enough to function In order for the Voyager probes to keep communicating with Earth their antennae must also be pointed at our planet If propellant lines freeze on either probe causing the antennae to point elsewhere we would lose the mission because we could no longer get a signal to the spacecraft Dodd explained And it s not just about the Voyager probes continuing to fly they need to operate with scientific instruments Before their -year anniversary in both spacecraft will likely need to have additional instruments and systems turned off The squad is hoping to keep the Cosmic Ray Subsystem running on Voyager as well as the magnetometer and Plasma Wave Subsystems on both spacecraft The instruments would enable both probes to essentially function like weather satellites in interstellar space sensing the habitat they re traveling through Dodd declared Scientists are interested in understanding how the sun s magnetic field changes and interacts at the heliopause the boundary of the heliosphere where hot solar wind streaming from the sun meets cold interstellar space Think of the heliopause like the shoreline of an ocean Dodd mentioned Wading into the water reveals ripples waves and other changing factors the farther you tour from shore and at several point things become more stable The Voyager probes are measuring the ripples or interactions between the heliopause our sun and interstellar space the farther the spacecraft expedition from the sun What s central is operating with these science instruments as long as realizable to make that map of what changes as you get away from the sun Dodd explained Dodd feels confident that at least one of the spacecraft can keep going for another two to five years The process of enabling the unprecedented missions to endure gets harder every year she reported But Voyager has a remarkable group behind it including NASA retirees in their s who advise on specific subsystems and club members so young that even their parents weren t born when the probes lifted off That kind of intergenerational effort on Voyager is really rewarding to see Dodd stated I love these spacecraft They re ambassadors for us here on Earth