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: Imagine for just a moment, sitting inside a cramped metal cylinder.
Speaker 3: Right like a really really small submarine.
Speaker 2: Exactly. The bulkheads around you are just packed tight with avionics,
Speaker 2: life support machinery, and the recycled air has this constant
Speaker 2: mechanical drone to it. You look out a reinforced quartz
Speaker 2: window and Earth is entirely gone, which.
Speaker 3: Is a terrifying thought on its own.
Speaker 2: Oh. Absolutely, And you've been sitting in this specific tiny
Speaker 2: geometry for over six months. Every single day, high energy
Speaker 2: galactic cosmic rays are passing right through the hule, just
Speaker 2: threading through your cellular structure, and.
Speaker 3: Your body is basically turning on itself at that point.
Speaker 2: Yeah, because you are in continuous microgravity, right, So your osteoclasts,
Speaker 2: those are the cells that break down bone tissue. They
Speaker 2: are operating way faster than your osteoblast can rebuild it.
Speaker 3: Your bones are literally dissolving.
Speaker 2: It's brutal. Your fluid distribution has shifted upward, increasing intracranial pressure,
Speaker 2: and it's actively altering the shape of your eyes. You
Speaker 2: are enduring this profound, basically systemic degradation of your own
Speaker 2: biology just to reach Mars.
Speaker 3: It forces us to confront a really dark reality about
Speaker 3: human physiology. We focus so heavily on this grand vision
Speaker 3: of becoming a multiplanetary species, you know, right, But the
Speaker 3: physiological toll of the commute itself is this massive barrier.
Speaker 3: The human organism is exquisitely calibrated for a one G
Speaker 3: environment and the protective magnetosphere of Earth.
Speaker 2: We are Earthlings through and through.
Speaker 3: Exactly remove those conditions for half a year and the
Speaker 3: body just initiates a cascade of systemic failures.
Speaker 2: So to understand exactly how we're going to fix this,
Speaker 2: we have to look at the radical shift NASA is
Speaker 2: aggressively pursuing. They are going after a technology that is
Speaker 2: lingered between like engineering reality and myth for sixty years.
Speaker 2: Nuclear propulsion, Yes, splitting atoms in space. We need to
Speaker 2: understand how this technology could cut the journey to Mars
Speaker 2: to just three or four months, which would make humanity
Speaker 2: a true spacefaring species.
Speaker 3: It's the ultimate game changer.
Speaker 2: But to understand why we are taking this massive nuclear leap,
Speaker 2: we first have to understand the fundamental flaw and how
Speaker 2: we currently get to space.
Speaker 3: Right, the old school methods.
Speaker 2: Yeah, every single spacecraft leaves Earth by burning chemical fuel.
Speaker 2: Rockets mix fuel with an oxidizer, they ignite it, and
Speaker 2: they blast expanding gas through a nozzle Newton's third law
Speaker 2: right right, Gas pushes down, rocket goes up.
Speaker 3: Simple physics.
Speaker 2: Okay, let's unpack this chemical propulsion is basically like a
Speaker 2: powerful kick. It's great for getting off the ground. But
Speaker 2: there's a glaring flaw here. You have to bring all
Speaker 2: that incredibly heavy fuel and the oxidizer with you.
Speaker 3: What's fascinating here is the vicious cycle of rocket mass.
Speaker 3: It is a literal mathematical trap.
Speaker 2: The rocket equation right.
Speaker 3: Exactly, the Silkovski rocket equation. You see. Much of a
Speaker 3: rocket's launch mass isn't the payload. It's not the astronauts
Speaker 3: or the shiny rovers you care about.
Speaker 2: What is it? Mostly it's just.
Speaker 3: The propellant required to move the propellant.
Speaker 2: Oh wow, so you're carrying fuel just to carry fuel.
Speaker 3: Yes, for a long, ambitious journey to Mars, this limitation
Speaker 3: becomes a massive, potentially insurmountable bottleneck. The specific impulse, which
Speaker 3: is basically the gas mileage of a rocket for our
Speaker 3: best chemical engines, hovers around four hundred and fifty.
Speaker 2: Seconds, and that's the absolute limit.
Speaker 3: Pretty much with chemical combustion, you are strictly bound by
Speaker 3: the chemical energy stored in the molecular bonds of the
Speaker 3: fuel and the oxidizer. Once you combust them, there is
Speaker 3: a hard physical limit to how fast you can eject
Speaker 3: that exhaust the nozzle.
Speaker 2: So if chemical rockets are just this quick, incredibly heavy kick,
Speaker 2: how do we actually sustain speed across millions of miles
Speaker 2: of empty space?
Speaker 3: That is where we enter the first of NASA's two
Speaker 3: nuclear strategies, right.
Speaker 2: The sprint approach. Yeah, nuclear thermal propulsion or NTP. Let's
Speaker 2: break this down. It's essentially a three step process, isn't it.
Speaker 3: It is. First, you have a nuclear reactor that splits
Speaker 3: uranium atoms to create massive, massive amounts of heat.
Speaker 2: We're talking over twenty five hundred Calvin right easily.
Speaker 3: Then step two you take liquid hydrogen, which is stored
Speaker 3: near absolute zero, and you pump it directly through that
Speaker 3: incredibly hot reactor.
Speaker 2: Core, which just sounds insanely violent.
Speaker 3: It is extreme engineering. The thermal shock is mind bottling.
Speaker 3: The liquid hydrogen flash boils instantly into a high.
Speaker 2: Pressure gas, and then step three, that superheated gas just
Speaker 2: lasts out the nozzle at extreme velocity.
Speaker 3: Yes, exactly, because hydrogen is the lightest element in the universe.
Speaker 3: When you impart that much thermal energy into it, the
Speaker 3: molecules accelerate to phenomenal speed. You effectively double your gas
Speaker 3: mileage compared to chemical rockets.
Speaker 2: So this is why you call it the sprint approach.
Speaker 3: Right. It can reduce travel times to Mars by up
Speaker 3: to twenty five percent. It turns a miserable six plus
Speaker 3: month voyage into a brisk three to four month sprint.
Speaker 2: And I want to point out this isn't just about impatience,
Speaker 2: you know, it's about survival. A shorter trip means drastically
Speaker 2: less exposure to cosmic radiation for the crew.
Speaker 3: That is the critical biological factor.
Speaker 2: Because galactic cosmic rays, these heavy atomic nuclei traveling at
Speaker 2: near light speed. When they hit a traditional metal hull,
Speaker 2: they don't just stop, No.
Speaker 3: They shatter. It causes spallation. It's like a shotgun blast
Speaker 3: of secondary radiation flooding the cabin. Adding thick shielding can
Speaker 3: actually make it worse because you're just giving the rays
Speaker 3: more material to smash into.
Speaker 2: So speed is the only real shield we have.
Speaker 3: Speed is your absolute best defense get out of deep
Speaker 3: space as quickly as possible.
Speaker 2: And sprinting also widens our launch windows right like currently,
Speaker 2: Earth and marks only aligned favorably every couple.
Speaker 3: Of years, every twenty six months. Yeah, you're locked into
Speaker 3: these slow, low energy home and transfer orbits.
Speaker 2: But NTP gives us the sheer speed and flexibility to
Speaker 2: launch more often, and crucially, it gives us an abort option.
Speaker 2: If something goes wrong on a chemical rocket halfway there,
Speaker 2: you're out of luck.
Speaker 3: You're writing it all the way to Mars.
Speaker 2: But with a thermal nuclear engine you actually have the
Speaker 2: power to hit the brakes and return to Earth if necessary.
Speaker 3: That safety margin alone makes NTP mandatory. But sprinting requires
Speaker 3: a massive amount of energy and liquid hydrogen is incredibly uncooperative.
Speaker 2: Yeah, it's not dense at all?
Speaker 3: Is it not even a little To carry enough of it?
Speaker 3: You need propellant tanks the size of office buildings, which
Speaker 3: is fine for a lightweight crew capsule, but terrible for
Speaker 3: hauling heavy cargo.
Speaker 2: So let me play Devil's advocate here for a second.
Speaker 2: If we have this incredible super fast thermal engine, why
Speaker 2: are we even bothering with this second type of engine?
Speaker 2: Isn't faster always better?
Speaker 3: Not if you're trying to move a mountain. That brings
Speaker 3: us to the second approach, Nuclear electric propulsion or ANYP
Speaker 3: the marathon rudder precisely. Instead of using the reactor for
Speaker 3: direct heat, it generates electricity megawatts of continuous electrical power, and.
Speaker 2: This electricity powers an ion thruster.
Speaker 3: Yes, it accelerates charged atoms, usually a heavy inert gas
Speaker 3: like xenon, out of the nozzle using electromagnetic fields.
Speaker 2: But the thrust is tiny, isn't it? I mean? I
Speaker 2: read that holding an ion thruster on Earth feels like
Speaker 2: holding a piece of paper.
Speaker 3: It is incredibly low thrust. If chemical propulsion is a
Speaker 3: powerful kick, ANYP is a persistent hand on the shoulder.
Speaker 2: The persistent hand on the shoulder, I like that.
Speaker 3: It's a gentle push, but it is incredibly fuel efficient,
Speaker 3: and it can run continuously for years.
Speaker 2: It's constantly accelerating, exactly.
Speaker 3: And the huge advantage here is that anyp remains highly
Speaker 3: effective far away from the.
Speaker 2: Sun right because usually ion thrusters use giant solar panels.
Speaker 3: But due to the inverse square law, solar energy drops
Speaker 3: off dramatically the further oute you go. By the time
Speaker 3: you reach Mars, sunlight is less than half as intense
Speaker 3: as it is at Earth.
Speaker 2: So a heavy cargo tug would need solar panels the
Speaker 2: size of football fields.
Speaker 3: Which are fragile and heavy. A nuclear reactor entirely bypasses that.
Speaker 3: It gives you massive power in total darkness.
Speaker 2: Okay, so how do these two distinct technologies, the sprinter
Speaker 2: and the marathon runner actually look when applied to a
Speaker 2: real scheduled mission.
Speaker 3: Well, this isn't just theoretical anymore.
Speaker 2: No, it's not. This brings us to NASA's concrete plan,
Speaker 2: the Space Reactor one or sr IE Freedom mission.
Speaker 3: This is the Pathfinder, targeted.
Speaker 2: For launch in December twenty twenty eight. It is going
Speaker 2: to be the first ever nuclear powered interplanetary spacecraft.
Speaker 3: It's an aggressive timeline, but it's absolutely necessary.
Speaker 2: And what's wild is its cargo. When it arrives at
Speaker 2: Mars roughly a year after launch, SR one Freedom is
Speaker 2: going to deploy the skyfall payload.
Speaker 3: The autonomous helicopter drones.
Speaker 2: Yeah, a whole fleet of them designed to scout the
Speaker 2: margin surface. But the aerodynamics of flying on Mars it's
Speaker 2: a nightmare, right.
Speaker 3: Oh, it's a brutal engineering paradox. The atmosphere is about
Speaker 3: one percent the density of Earth's, so you have to
Speaker 3: spin the rotor blades incredibly fast to generate any lift.
Speaker 2: But the speed of sound is much lower there because
Speaker 2: it's cold and mostly carbon dioxide.
Speaker 3: Exactly, it's around two hundred and forty meters per second.
Speaker 3: So as those rotors spin faster to catch that thin air,
Speaker 3: the tips of the blades approach the Martian speed of sound.
Speaker 2: Which creates massive shockwaves in drag.
Speaker 3: It's a very narrow, punishing aerodynamic envelope.
Speaker 2: But if we connect this to the bigger picture, the
Speaker 2: true purpose of SR one Freedom isn't actually just to
Speaker 2: drop off these cool drones, is it.
Speaker 3: No, not at all. If we connect this to the
Speaker 3: bigger picture, SR one Freedom is an uncrewed. Any p
Speaker 3: mission meant to prove the bus itself.
Speaker 2: Prove that a space rated fission reactor can actually work.
Speaker 3: Yes, it has to prove that nuclear energy can provide
Speaker 3: sustained high efficiency power in deep space. It's about creating
Speaker 3: a regulatory precedent and activating an industrial base for future
Speaker 3: nuclear fsion systems.
Speaker 2: Right, waking up the supply chain, the safety protocols, all
Speaker 2: of it. Because proving this technology with robots is one thing,
Speaker 2: but how does this change the game for human astronauts.
Speaker 3: This is where we bring everything together.
Speaker 2: Because let's face it, our bodies are not built for space.
Speaker 2: We talked about the bone and muscle loss, the radiation risks.
Speaker 3: So we use the ultimate tag team strategy. We don't
Speaker 3: just use one engine, we use both.
Speaker 2: Oh, this is the split mission architecture exactly.
Speaker 3: Step one is the marathon. You send the heavy vital cargo,
Speaker 3: the habitats, years of food supplies, life support machinery, huge
Speaker 3: pressurized rovers using the highly fuel efficient nuclear electric propulsion.
Speaker 2: Right, Because it doesn't matter if a carbon fiber habitat
Speaker 2: takes nine months or even eighteen months to arrive, it
Speaker 2: doesn't get cancer.
Speaker 3: Exactly, You use the incredible efficiency of any p to
Speaker 3: haul all that mass slowly, but surely you preposition everything
Speaker 3: on the Martian surface.
Speaker 2: So it's all just waiting there fully operational yep.
Speaker 3: And once mission control confirms that the fully stock base
Speaker 3: is ready, then and only then do you initiate step two.
Speaker 3: You launch the human crew using nuclear thermal propulsion.
Speaker 2: Because they aren't dragging thousands of tons of cargo, they
Speaker 2: can just punge it.
Speaker 3: They make the crossing in a brisk three to four months,
Speaker 3: minimizing all those health risks, and they arrive at a
Speaker 3: fully prepared infrastructure.
Speaker 2: It sounds like a perfect, flawless plan. So what is
Speaker 2: standing in the way of a twenty twenty eight launch reality?
Speaker 3: Physics, yeah, and bureaucracy yeah.
Speaker 2: So what does this all mean. We've known the physics
Speaker 2: of nuclear propulsion since the Cold War. The physics are sound.
Speaker 2: Why are we only targeting this now? And why is
Speaker 2: December twenty twenty eight considered incredibly ambitious?
Speaker 3: Well, the push really started aggressively when Jared Isaacman took
Speaker 3: over as the agency's chief back in December twenty twenty five.
Speaker 2: Right, he made this his absolute priority.
Speaker 3: She fundamentally believes this technology will truly unlock human kind's
Speaker 3: ability to explore among the stars. But enthusiasm doesn't rewrite
Speaker 3: the laws of thermodynamics.
Speaker 2: That it definitely doesn't.
Speaker 3: The monumental engineering and regulatory hurdles are sobering, and any
Speaker 3: PECE spacecraft requires flawless integration of a reactor, massive shielding,
Speaker 3: heat management, power conversion, radiators, electric thrusters, just an unbelievable
Speaker 3: amount of tech and fault tolerance. Because in space convection
Speaker 3: doesn't exist. You have to reject the massive waste heat
Speaker 3: from the reactor as infrared radiation.
Speaker 2: Wait, so the reactor heat could literally melt the other
Speaker 2: components oh easily.
Speaker 3: If the heat management system fails, that thermal energy will
Speaker 3: travel right through the chassis and physically melt the avionics
Speaker 3: and the payload.
Speaker 2: That is terrifying.
Speaker 3: And you have the radiation environment created by your own
Speaker 3: power source. You need rad hardened microchips that won't suffer
Speaker 3: from single event upsets where a rogue neutron literally flips
Speaker 3: a zeri to a one and crashes your flight computer.
Speaker 2: So you need computers that can autonomously heal themselves. Because
Speaker 2: the communication light the late of Mars means Earth can't
Speaker 2: help been real time.
Speaker 3: Exactly, And look at the historical track record. Making this safe, affordable,
Speaker 3: and able to pass regulatory safety standards is brutal.
Speaker 2: Yeah, I mean the US has only ever launched one
Speaker 2: fission reactor into.
Speaker 3: Orbit, yes, NAP ten, a way back in nineteen.
Speaker 2: Sixty five, and it only ran for what forty three days?
Speaker 3: Forty three days before a voltage regulator failed and shut
Speaker 3: the whole thing down. Since then, we've only used RTGs
Speaker 3: radioisotope thermoelectric generators on things like the Curiosity rover.
Speaker 2: But those just use passive K heat. They don't split atoms.
Speaker 3: Right, they produce a tiny trickle of power to jump
Speaker 3: from that to a No, it's about breaking down the
Speaker 3: barriers of deep space entirely.
Speaker 2: Think about it. If we successfully tamed the power of
Speaker 2: a nuclear reactor to push this across the void, turning
Speaker 2: an expedition of pure survival into a routine three month commute,
Speaker 2: where does the boundary of human territory actually stop?
Speaker 3: If Mars is just three months away, the outer Solar
Speaker 3: system open up.
Speaker 2: Exactly what becomes our next impossible destination? Could we use
Speaker 2: this to haul submarines to Jupiter's moon Europa, or set
Speaker 2: up atmospheric processing plants on Titan.
Speaker 3: The asteroid belt becomes a viable logistical hub instead of
Speaker 3: just a deep space anomaly.
Speaker 2: The systems we're forcing into existence for this twenty twenty
Speaker 2: eight window are the exact same engines that will turn
Speaker 2: us into a true deep space civilization. So thank you
Speaker 2: for joining us on this exploration of the future of
Speaker 2: space travel. Keep your eyes on the stars, and definitely
Speaker 2: keep your eyes on the launch pads. In December twenty
Speaker 2: twenty eight,