Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomie podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: So imagine for a second that you're trying to troubleshoot
Speaker 2: and maintain this vintage nineteen seventies machine, like say, a
Speaker 2: classic car. But there's a catch, right, A pretty big
Speaker 2: catch in this case, Yeah, a massive one. The car
Speaker 2: is currently flying through absolute darkness, something like fifteen billion
Speaker 2: miles away from the mechanic, and on top of that,
Speaker 2: its battery is just, you know, slowly and permanently dying.
Speaker 3: It's a terrifying scenario if you're the mechanics exactly.
Speaker 2: But that is the literal reality for the team at
Speaker 2: NASA's Jet Propulsion Laboratory, because on April seventeen, twenty twenty six,
Speaker 2: those engineers sent commands to shut down a major instrument,
Speaker 2: the Low Energy Charged Particles Experiment, or the LCP on
Speaker 2: the Voyager one spacecraft.
Speaker 3: Which I mean, nationally sounds like bad news, right when
Speaker 3: you hear they're turning.
Speaker 2: Things off, right, you think it's breaking. But our mission
Speaker 2: for this deep dive today is to really unpack why
Speaker 2: that isn't the case. We're getting into the sources today
Speaker 2: to show that this isn't just a story about a
Speaker 2: machine breaking down. It's it's actually this incredible story of survival.
Speaker 2: We're looking at these razor thin margins, the staggering physics
Speaker 2: of managing power in deep space, and you know what,
Speaker 2: this little probe that could is still whispering back to
Speaker 2: Earth from the interstellar void.
Speaker 3: Yeah, and I think it's important to set the tone
Speaker 3: right away. Voyager one launched on September five, nineteen seventy seven,
Speaker 3: so we're talking about a near forty nine year legacy here,
Speaker 3: which is just wild, it really is. And the key
Speaker 3: takeaway from the mission logs and the engineering briefs we've
Speaker 3: been reviewing is that shutting off the LECP is absolutely
Speaker 3: not a failure. It is a highly strategic, incredibly calculated
Speaker 3: maneuver to keep humanity's farthest outpost alive.
Speaker 2: Yeah, it's like they're not just passively watching the lights
Speaker 2: go out.
Speaker 3: No, not at all.
Speaker 2: They're making this proactive choice. But before we even get
Speaker 2: into what the LCP is and why they turned it off,
Speaker 2: I feel like we need to talk about the how,
Speaker 2: because just turning off a switch that far away is
Speaker 2: a logistical nightmare.
Speaker 3: Oh completely. The sheer friction of trying to communicate with
Speaker 3: Voyager one right now is well, it's almost impossible to wrap.
Speaker 2: Your head around, right because it's over fifteen billion miles away,
Speaker 2: which is about twenty five billion kilometers, and.
Speaker 3: At that distance, even light, which is the absolute speed
Speaker 3: limit of the universe, it takes a long time to travel.
Speaker 2: Yeah, it's not instantaneous. Like if I send a text
Speaker 2: message to a friend across the globe, it's basically instant
Speaker 2: But sending a text to Voyager it takes.
Speaker 3: Roughly twenty three hours just for the signal to reach
Speaker 3: the spacecraft twenty three hours, and then you have to
Speaker 3: wait another twenty three hours just for the confirmation ping
Speaker 3: to come back to Earth and say hey, I got
Speaker 3: the message.
Speaker 2: So wait, you send a command that is going to
Speaker 2: permanently alter this historic spacecraft, and then you just have
Speaker 2: to sit on your hands for almost two days waiting
Speaker 2: to see if it worked. I mean, how does a
Speaker 2: team even manage a procedure with that kind of lag?
Speaker 2: The psychological tension must be unbearable.
Speaker 3: It requires a level of operational discipline that is just
Speaker 3: it's unique to the Voyager interstellar mission. You can't just
Speaker 3: press a button. It involves the deep space network, right,
Speaker 3: these giant seventy meters antennas on Earth.
Speaker 2: Because the signal is so weak by the time it.
Speaker 3: Gets there exactly, they're pumping tens of kilowatts of power
Speaker 3: out of these massive dishes. But by the time that
Speaker 3: radio wave expands over fifteen billion miles, Voyagers catching a
Speaker 3: signal that's you know, a fraction of a billionth of
Speaker 3: a watt. Wow, And it gets crazier. Because the computer's
Speaker 3: on Voyager from the seventies, they have incredibly limited memory.
Speaker 2: Like less memory than a modern keyfob.
Speaker 3: Basically, yeah, so they aren't just sending an off command.
Speaker 3: They're doing this heavily choreographed digital surgery. They have to
Speaker 3: creatively reprogram these aging computers using sequential octal code, slotting
Speaker 3: it into specific memory addresses.
Speaker 2: Without messing up the core code that keeps the antenna
Speaker 2: pointed at Earth.
Speaker 3: Right, because if the antenna drifts, you lose the spacecraft forever.
Speaker 3: There's zero room for error and that specific LACP shut
Speaker 3: down sequence we're talking about. Once the command arrived, it
Speaker 3: took the spacecraft about three hours and fifteen minutes just
Speaker 3: to execute it.
Speaker 2: Okay, So that really paints a picture of how hard
Speaker 2: it is to just talk to this thing. But that
Speaker 2: leads us to the grim reality that actually forced them
Speaker 2: to send that command in the first place. The spacecraft
Speaker 2: is starving.
Speaker 3: Starving for power. Yes, this is the core engineering crisis
Speaker 3: of the whole mission.
Speaker 2: Right, and to understand that, we have to look at
Speaker 2: how it gets its power because it doesn't use solar panels. Right,
Speaker 2: the sun is way too far away.
Speaker 3: Yeah, out there, the sun is just a slightly brighter
Speaker 3: star in the sky. So instead both voyagers are power
Speaker 3: b these things called RTGs radioisotope thermoelectric generators.
Speaker 2: Okay, RTGs, how do those actually work?
Speaker 1: Well?
Speaker 3: They rely on the radioactive decay of plutonium two thirty
Speaker 3: eight inside these generators. As the plutonium naturally decays, it
Speaker 3: gives off a lot of heat, and the RTGs basically
Speaker 3: convert that heat directly into electricity. Using the temperature difference
Speaker 3: between the hot plutonium and the cold vacuum of space.
Speaker 2: It's just solid state physics, no moving parts, right.
Speaker 3: No moving parts to break down, which is why it's
Speaker 3: lasted almost fifty years. But here's the catch. Physics is relentless.
Speaker 3: The plutonium is literally decaying away, right.
Speaker 2: It's a finite resource.
Speaker 3: Exactly at launch in nineteen seventy seven, those RTGs provided
Speaker 3: about four hundred and seventy watts combined, but because of
Speaker 3: the natural half life of the plutonium, they lose about
Speaker 3: four watts of power every single.
Speaker 2: Year, four watts a year. I kind of visualize that like,
Speaker 2: you know, being stuck in this massive, freezing dark room
Speaker 2: and the only light bulb keeping you warm is just slowly,
Speaker 2: irreversibly dimming.
Speaker 3: That is a very accurate way to look at it,
Speaker 3: because by twenty twenty six, those power levels have gotten
Speaker 3: critically low.
Speaker 2: So if the margins are so razor thin, how do
Speaker 2: the engineers even decide what stays on? Like, how do
Speaker 2: you choose between keeping the spacecraft's brain warm and keeping
Speaker 2: its eyes open.
Speaker 3: It is a brutal process of triage. Every single watt
Speaker 3: is aggressively accounted for they have to balance the science operations,
Speaker 3: the instruments gathering data with the essential systems like the
Speaker 3: computer and the transmitter needed to beam that data back
Speaker 3: to Earth.
Speaker 2: Yeah, because if it can't transmit, what's the point.
Speaker 3: Right, But the real balancing act, the thing that dictates everything,
Speaker 3: is thermal managing it. Deep space is effectively absolute zero,
Speaker 3: and Voyager uses this propellant called hydrazine for its tiny
Speaker 3: thrusters to keep the antenna pointed at.
Speaker 2: Earth, and hydrozen can freeze.
Speaker 3: It freezes at roughly two degrees celsius. If the fuel
Speaker 3: lines get too cold, the hydrozene freeze is solid, the
Speaker 3: lines could rupture and the spacecraft loses the ability to
Speaker 3: point out Earth.
Speaker 2: Mission over Oh wow, So they literally have to use
Speaker 2: electricity just to run heaters on the fuel lines.
Speaker 3: Exactly, And over the decades they've deactivated every non essential heater.
Speaker 3: But eventually you run out of easy things to turn.
Speaker 2: Off, which brings us to the tipping point because that
Speaker 2: for wat annual drain. You know, it's a slow bleed,
Speaker 2: you can plan for that. But looking at the sources,
Speaker 2: there was actually a very sudden, specific catalyst that forced
Speaker 2: NASA's hand in April of twenty twenty six.
Speaker 3: Yeah, it wasn't just the gradual decay. On February twenty seventh,
Speaker 3: twenty twenty six, the spacecraft was performing this routine roll
Speaker 3: maneuver basically rotating to calibrate its instruments.
Speaker 2: Okay, a routine roll.
Speaker 3: What happened well, during that maneuver, there was an unexpected
Speaker 3: power dip. The voltage on the main electrical bus dropped,
Speaker 3: and that is incredibly dangerous because Voyager has this on
Speaker 3: board defense mechanism and Atomas fault protection system.
Speaker 2: It's kind of like a computer safe mode sort.
Speaker 3: Of, but way more aggressive. If the fault protection system
Speaker 3: senses that the spacecraft is growing more power than it has,
Speaker 3: you'll just blindly start shutting things down to save the
Speaker 3: core systems.
Speaker 2: And you desperately want to avoid triggering that, right because
Speaker 2: trying to reboot a forty nine year old operating system
Speaker 2: from scratch while it's in safe mode sounds terrifying.
Speaker 3: It is the absolute worst case scenario because if it
Speaker 3: shuts down the wrong heater autonomously and the fuel lines
Speaker 3: freeze before Earth even knows what happened.
Speaker 2: Because of the twenty three hour delay, exactly.
Speaker 3: By the time JPL gets the telemetry, the mission could
Speaker 3: already be dead, so the engineers had to intervene. The
Speaker 3: LACP shutdown was actually part of a pre planned sequence
Speaker 3: that they agreed on years ago. They knew this day
Speaker 3: was coming.
Speaker 2: So is proactive amputation like setting off an instrument early?
Speaker 2: Is that always safer than just letting the spacecraft's own
Speaker 2: defense mechanisms kick in?
Speaker 3: Without a doubt, It's all about buying precious time and
Speaker 3: maintaining control. By acting first and shutting down the LACP
Speaker 3: in a controlled, orderly manner, they lowered the overall power draw,
Speaker 3: stabilized the voltage, and kept the fault protection system from
Speaker 3: waking up.
Speaker 2: Okay, so that's seven of the ten original instruments now
Speaker 2: turned off on Voyager one, right yep.
Speaker 3: Voyager two actually had its LCP deactivated earlier in March
Speaker 3: of twenty twenty five, and Voyager one lost this cosmic
Speaker 3: ray subsystem in February twenty twenty five.
Speaker 2: It really highlights the foresight of the engineering teams to
Speaker 2: have this exact sequence of prioritization mapped out years in advance.
Speaker 2: But I want to talk about the specific instrument that
Speaker 2: drew the short straw this time, because we're saying farewell
Speaker 2: to the LACP and it has this incredible legacy.
Speaker 3: It really does. The Low Energy Charged Particles Experiment has
Speaker 3: been running almost continuously since nineteen seventy seven.
Speaker 2: What was it actually doing out there?
Speaker 3: It measures ions, electrons and cosmic rays for decades. It
Speaker 3: was instrumental in mapping the outer layers of the heliosphere,
Speaker 3: which is the big protective bubble our Sun creates. It
Speaker 3: tracked how the solar wind from our Sun interacts with
Speaker 3: the plasma from interstellar space, and it actually proved that
Speaker 3: the intensity of cosmic rays is lower inside our Solar
Speaker 3: system some's bubble than outside of it.
Speaker 2: So it was basically the ship's lookout, just standing on
Speaker 2: the bow of Voyager feeling the physical spray of the
Speaker 2: cosmic ocean and telling us exactly where the safety of
Speaker 2: our solar system ends and the wild interstellar sea begins.
Speaker 3: It's a great analogy. It physically felt the transition when
Speaker 3: Voyager one crossed into interstellar space in twenty twelve.
Speaker 2: But since Voyager one is literally the only thing out
Speaker 2: there right now, how devastating is this loss? I mean,
Speaker 2: are we just flying blind now? When it comes to
Speaker 2: understanding the interstellar medium.
Speaker 3: Well, it is a significant loss. Absolutely. The data the
Speaker 3: LEECP provided was wholly unique. Literally, no other human made
Speaker 3: object has explored this region. But it's important to contextualize it.
Speaker 3: The science team got decades of foundational data about that
Speaker 3: boundary where the suns influence wanes and galactic forces take over.
Speaker 2: They map the border.
Speaker 3: Yes, and here's a truly fascinating, kind of hopeful detail
Speaker 3: from the shut down procedure. When they sent the command
Speaker 3: to kill the power to the LACP, they deliberately left
Speaker 3: one small part of it active.
Speaker 2: Wait really, with apart.
Speaker 3: A tiny low power step promotor that physically spins the sensor.
Speaker 2: Why on Earth would you leave a motor running if
Speaker 2: you're so desperate for every fraction of a wat.
Speaker 3: Because of the cold vacuum of space, if you stop
Speaker 3: a metal gear from moving out there for too long,
Speaker 3: the metal parts can literally fuse together in a process
Speaker 3: called cold welding.
Speaker 2: Oh wow, So if they turn it off, it's permanently
Speaker 2: welded shut.
Speaker 3: Exactly, So they intentionally left the motor taking over just
Speaker 3: in case by some miracle, power margins improve in the
Speaker 3: future and they want to reactivate it.
Speaker 2: That is just incredible. They're shutting down the lab but
Speaker 2: leaving the key in the lock, just stubbornly refusing to
Speaker 2: close the door completely.
Speaker 3: It's that JPL engineering mindset, never say never.
Speaker 2: Okay, so the LACP is offline, but Voyager one isn't dead.
Speaker 2: What exactly is left? What are the final senses this
Speaker 2: spacecraft still possesses to navigate?
Speaker 3: There are only two primary science instruments left running, the magnetometer,
Speaker 3: which measures magnetic fields, and the plasma wave subsystem, which
Speaker 3: detects plasma waves and oscillations in the environment.
Speaker 2: So it's essentially been stripped down to a compass and
Speaker 2: a microphone. Basically, yes, it can't see the particles anymore
Speaker 2: like the LACP did, but it can feel the magnetic
Speaker 2: pole with the compass, and it can hear the vibrations
Speaker 2: of the plasma with the microphone. What kind of picture
Speaker 2: does that actually paint of interstellar space?
Speaker 3: Like?
Speaker 2: What are we learning from that?
Speaker 3: Quite a lot? Actually, the magnetometer is incredibly valuable. It
Speaker 3: provides continuous readings of the interstellar magnetic field. It shows
Speaker 3: scientists how the Sun's magnetic field, that big bubble actually
Speaker 3: drapes and interacts at the boundary with the galaxy's magnetic.
Speaker 2: Field, right like currents in an ocean meeting each other exactly.
Speaker 3: And the plasma wave instrument the microphone is listening to
Speaker 3: shocks in the sparse plasma environment. When the Sun spits
Speaker 3: out a massive solar flare, that shockwave eventually hits interstellar space,
Speaker 3: and the PLA l Asthma wave subsystem can literally hear
Speaker 3: the plasma ringing like a bell. That is so cool
Speaker 3: it is. And NASA hopes they can run these two
Speaker 3: remaining instruments for about another year under the current power.
Speaker 2: Constraint, just a year because of that four walt drain.
Speaker 3: Right. But and this is where the story gets really wild.
Speaker 3: The JPL engineers are not just passively watching the clock
Speaker 3: tick down on that year.
Speaker 2: No, of course not.
Speaker 3: They have a plan, the very radical intervention planned. It's
Speaker 3: called the Big Bang Power Saving Initiative.
Speaker 2: The Big Bang GAMUT. I was visibly shocked when I
Speaker 2: read the details of this in the sources. It sounds
Speaker 2: completely insane. Walk us through what this actually is.
Speaker 3: So the problem with turning off components to save power
Speaker 3: is that those components generate waste heat and that waste
Speaker 3: heat actually helps keep the spacecraft warm. Specifically, it helps
Speaker 3: keep those crucial hydrazene fuel lines from freezing.
Speaker 2: Ah, so if you just turn off a radio or
Speaker 2: a sensor, that part of the ship gets too cold.
Speaker 3: Exactly. So, the Big Bang initiative involves hot swapping multiple
Speaker 3: powered devices all at once. They want to simultaneously switch
Speaker 3: to lower power alternatives to drop the overall power draw,
Speaker 3: but do it so quickly and carefully that the thermal
Speaker 3: stability of the spacecraft isn't compromised.
Speaker 2: That is, I mean, I described it in my notes
Speaker 2: as doing a heart transplant while the patient is sprinting
Speaker 2: away from you.
Speaker 3: It's an apt description.
Speaker 2: But if power margins are already razor thin and every
Speaker 2: single watt is quite literally life or death, isn't swapping
Speaker 2: multiple devices at once an incredibly terrifying gamble, Like if
Speaker 2: the voltage drops for a second, want it trigger that
Speaker 2: fault protection system we talked about?
Speaker 3: It absolutely could. It is a massive gamble, but it's
Speaker 3: a necessary one to combat the physics of the decaying plutonium.
Speaker 3: And they aren't going in blind. They have a brilliant
Speaker 3: risk mitigation strategy.
Speaker 2: They're going to test it on Voyager two.
Speaker 3: First. Yes, Voyager two is in a slightly healthier power state.
Speaker 3: So the plan is to test the big bang maneuver
Speaker 3: on Voyager two in May or June of twenty twenty six.
Speaker 2: Using it as the canary in the coal mine exactly.
Speaker 3: And if it's successful, if the thermal mass holds and
Speaker 3: the voltage stabilizes, then they will attempt it on Voyager
Speaker 3: one note earlier than July.
Speaker 2: Wow. And if it works, what's the payoff for taking
Speaker 2: that risk?
Speaker 3: Success could extend the science operations of the final instruments
Speaker 3: toward twenty thirty, So.
Speaker 2: They buy themselves four extra years.
Speaker 3: Four extra years of absolutely irreplaceable data from the deepest
Speaker 3: reaches of space human technology has ever reached.
Speaker 2: Which really makes you step back and appreciate the grand
Speaker 2: legacy of this whole mission. I mean to understand why
Speaker 2: engineers in twenty twenty six are fighting so fiercely for
Speaker 2: a single extra watt. You have to look at the
Speaker 2: staggering resume of Voyager over the last forty nine years.
Speaker 3: It is unmatched in the history of space exploration.
Speaker 2: Seriously, like it launched during this rare planetary alignment right,
Speaker 2: a gravity assist trajectory that only happens once every one
Speaker 2: hundred and seventy five years, right.
Speaker 3: The Grand Tour. It allowed the voyagers to use the
Speaker 3: gravity of Jupiter to slingshot to Saturn and so on.
Speaker 2: In the encounters Jupiter in nineteen seventy nine, getting those
Speaker 2: close ups to the Great Red Spot.
Speaker 3: And discovering active volcanoes on Jupiter's moon, I owe that
Speaker 3: was a paradigm shift. We thought moons were dead rocks,
Speaker 3: and suddenly we see volcanos erupting in deep space.
Speaker 2: Then Saturn in nineteen eighty, the intricate structure of the
Speaker 2: rings diving into the thick atmosphere of Titan, and.
Speaker 3: Then the pivot. The planetary mission ended and the Voyager
Speaker 3: interstellar mission began. Voyager one crossed the heliopause in twenty
Speaker 3: twelve and Voyager two followed in twenty eighteen.
Speaker 2: They discovered the magnetic highway out there. It's just a
Speaker 2: historical juxtaposition that blows my mind. These machines were built
Speaker 2: in an era of eight track tapes and murdery phones,
Speaker 2: yet they became our first interstellar scouts.
Speaker 3: It's phenomenal engineering.
Speaker 2: But I'm curious, how is data from a nineteen seventies
Speaker 2: probe still directly influencing modern space programs today, Like why
Speaker 2: does NASA need this data for things happening now?
Speaker 3: Because it connects directly to humanity's future in space. Think
Speaker 3: about the Artemis program, Right, we're trying to send humans
Speaker 3: back to the Moon and eventually to Mars.
Speaker 2: Right, long duration crude missions.
Speaker 3: The biggest thread out there isn't prepared. It's radiation. The
Speaker 3: decades of data Voyager collected regarding cosmic radiation and galactic
Speaker 3: environments directly inform the shielding models we use today. You
Speaker 3: can't design a safe Mars spacecraft without knowing exactly what
Speaker 3: kind of radiation environment it's flying into, and Voyager is
Speaker 3: the only probe that's actually out there measuring it.
Speaker 2: So the data from the LACP is actively protecting future.
Speaker 3: Astronauts absolutely, and it also informs the design of future
Speaker 3: interstellar probes. Fodger proved that with careful husbandry, machines can
Speaker 3: endure decades beyond their design expectations.
Speaker 2: Yeah, the sheer stubbornness of the human element. The engineers
Speaker 2: from the seventies passing the baton to the operators in
Speaker 2: twenty twenty.
Speaker 3: Six, it spans generations.
Speaker 2: Well, this has been an incredible journey today, just to
Speaker 2: quickly recap for everyone, We've walked through the agonizing twenty
Speaker 2: three hour delay of sending the command to shut down
Speaker 2: the LACP. We looked at the physical reality of those
Speaker 2: decaying RTG power sources losing four watts a year, and
Speaker 2: why the freezing point of hydrozene dictates every single decision, and.
Speaker 3: We cover the audacity of that upcoming Big Bang test
Speaker 3: to keep those final two instruments running.
Speaker 2: Exactly So to everyone listening, I hope it's clear now
Speaker 2: that shutting off the LACP is not the end. It's
Speaker 2: this brilliant strategic pause in an epic saga.
Speaker 3: Every single additional day we receive data from that magnetometer
Speaker 3: and plasma wave subsystem is a profound victory for human
Speaker 3: ingenuity and curiosity.
Speaker 2: It really is. But I want to leave you with
Speaker 2: one final kind of provocative thought before we sign off today.
Speaker 2: Voyager one is currently traveling at roughly thirty eight thousand
Speaker 2: miles per hour, heading generally toward the constellation of Fucus. Now, eventually,
Speaker 2: the projections say around twenty thirty two or twenty thirty five,
Speaker 2: the power will finally drop solow that total communication loss
Speaker 2: will happen.
Speaker 3: The RTGs will simply not have the power to run
Speaker 3: the transmitter right.
Speaker 2: It will go silent. That the spacecraft itself won't stop.
Speaker 2: It will continue to drift completely frozen for millions, maybe
Speaker 2: billions of years and bolted to its side. Is the
Speaker 2: Golden record, that time capsule of Earth's sounds, music and images.
Speaker 2: So long after our deep space antennas lose Voyager one signal,
Speaker 2: it will still be out there in the dark. It's
Speaker 2: going to take tens of thousands of years just to
Speaker 2: approach another star system. So think about this. If someone
Speaker 2: or something eventually intercepts that silent probe drifting through the
Speaker 2: galaxy and they somehow decode that Golden record, will they
Speaker 2: ever be able to comprehend the sheer, stubborn human willpower
Speaker 2: it took just to keep its eyes open for one
Speaker 2: more year.