Space Elevators, Skyhooks, and Space Fountains

Episode Summary

Executive Summary: The episode explores the weirdest, slowest, cheapest, and fastest ways to reach space, starting with the infamous 1957 Plumbbob borehole cover that may have been launched faster than any human-made object. It then contrasts rockets with hypothetical space infrastructure—stairs, escalators, sky hooks, launch loops, and especially a space elevator—arguing that humanity needs bold public space projects, not just private rocket launches.

Main Topics: The borehole cover as the fastest and worst way to space (Priority: 5/5): The hosts recount the Operation Plumbbob/Pascal B nuclear test where a 2,000 kg steel lid may have been blasted into space at extreme speed, possibly the fastest human launch ever, but almost certainly destroyed on reentry. Defining “space” and the meaning of the Kármán line (Priority: 4/5): They discuss outer space as a practical boundary, settling on the Kármán line at 100 km, while jokingly using the ‘Katy Perry line’ at 105 km as a lower limit for the episode’s purposes. The absurdly slow route: waiting for Earth to move you into space (Priority: 4/5): A long-term cosmological thought experiment imagines Earth being swallowed by the Sun, ejected from the solar system, then potentially from the galaxy, and eventually losing its protons over unimaginable timescales. Why rockets are effective but costly and limited (Priority: 5/5): Rockets remain the real-world method for launch, but they are expensive, noisy, wasteful, and risky, with launch costs cited at thousands of dollars per kilogram to low Earth orbit. Orbital mechanics, free fall, and Newton’s cannon (Priority: 5/5): The episode explains orbit as continuous falling around Earth, where horizontal velocity and gravity combine so that the surface curves away beneath the object, enabling the ISS and similar spacecraft to remain aloft. Engineering alternatives to rockets: stairs, space elevators, sky hooks, launch loops (Priority: 5/5): The hosts playfully but seriously examine non-rocket infrastructure concepts that could reduce launch costs, emphasizing that a space elevator or launch loop would be transformative if materials and engineering allowed it. The social and political meaning of space infrastructure (Priority: 4/5): The discussion closes by weighing public benefit, wonder, and opportunity against privatization, inequality, and resource priorities, arguing that large-scale space projects can inspire humanity but should not become exclusive corporate assets.

Key Arguments: The borehole cover story shows that the fastest possible launch can also be the worst and least humane way to get to space, since anything launched that violently would likely ablate in the atmosphere. Space is not a single obvious boundary, so the podcast adopts the Kármán line as a practical definition for discussion, even though different institutions use slightly different thresholds. Waiting for Earth itself to drift into space is technically possible over cosmic timescales, but the times involved are so huge that it is not a meaningful travel strategy. Rockets work because they are simple and proven, but the massive propellant burden makes them expensive and inefficient compared with infrastructure-based launch systems. Orbit is not “no gravity”; it is free fall with sufficient sideways speed that the Earth curves away beneath the object. A space elevator would dramatically lower access-to-space costs, but current materials are not yet strong enough for the required tether length and tensile loads. A sky hook or launch loop could be more feasible than a full space elevator because they shift the engineering problem toward rotating tethers and active support rather than static megastructures. Big public projects like the moon landing show that space exploration can unite people, generate awe, and create shared civic meaning, even if the practical benefits are less direct than those of antibiotics or computers. The hosts worry that as space becomes more private and commercial, access, ownership, and benefits will be concentrated rather than shared. Humanity needs both practical problem-solving on Earth and ambitious, inspiring space projects; the right answer is not either/or.

Data Points: Operation Plumbbob borehole cover mass: 2,000 kilograms (about 900 pounds) - The steel lid placed over the borehole before the Pascal B nuclear test Estimated launch speed of the cover: About 150,000 miles per hour (67 km/s) - Reverse-engineered from a single camera frame Escape velocity comparison: About 6× Earth escape velocity - Used to estimate how fast the lid was traveling Kármán line: 100 kilometers (62 miles) - Widely recognized boundary between atmosphere and space Katy Perry flight altitude: 105 kilometers (65 miles) - Used jokingly as a practical lower limit for the episode International Space Station altitude: 400 kilometers (250 miles) - Compared with the Kármán line to show how much higher the ISS orbits ISS gravity level: About 90% of surface gravity - Illustrates that astronauts are weightless because of free fall, not because gravity disappears Launch cost to low Earth orbit: $2,000–$3,000 per kilogram - Approximate cost using Falcon Heavy/Falcon 9-class reusable rockets Step count to the Kármán line: 555,556 steps - Assuming 18 cm per step in a hypothetical stairway to space Time to climb to space: More than 3 months - Estimate for a healthy person climbing continuously without sleep Burj Khalifa height: 0.8 kilometers - Used to show how far a real building is from space Burj Khalifa steps: 2,909 steps - Compared to the half-million-plus steps needed for a space staircase World-record stair climb: 18.7 km vertical in 24 hours - Christian Roberto Lopez Rodriguez’s stair-climbing record Week-long stair-climbing record: 100.475 kilometers vertical - Same athlete exceeded the Kármán line in cumulative stair climbing Orbital speed at 6 feet above Earth: 7,910 m/s - Theoretical speed needed for a baseball to orbit at human height ISS orbital speed: 7,670 m/s - Used for comparison with orbital baseball speed Orbital speed at 6 feet above the Moon: 1,600 m/s - Much lower lunar orbital speed due to weaker gravity Fast bullet speed: Mach 4.7 - A brass projectile from Banana Ballistics compared with lunar orbital speed Projectile mass: 12.5 grains - Brass bullet used in the fast-bullet example Geostationary orbit altitude: 35,786 kilometers - The height where orbital period matches Earth’s rotation Proton decay lower bound: 100 undecillion years - Timescale given for eventual evaporation of all protons if proton decay occurs

Pivotal Quotes: "The cheapest, fastest. And worst way to go to space would have been to have been a borehole cover in 1957 during Operation Plumbbob." — Hannah Fry: Opening punchline describing the episode’s central historical anecdote "The reason the astronauts in the International Space Station are floating around isn't that there's no gravity. There's a bunch of gravity." — Michael Stevens: Explaining orbit as free fall rather than gravity-free motion "These, meaning the rockets, the space infrastructure, the events, the adventures, they are our cathedrals." — Paul Goodman (quoted by the hosts): Used to defend ambitious public space projects as culturally valuable

Implications: The episode argues for investing in shared, long-horizon space infrastructure and science, while resisting a future where access to space is privatized. It frames space as both a technical challenge and a civic project.