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Is interstellar travel possible? – with Les Johnson

The Royal Institution・47 minutes read

The speaker discusses the challenges of interstellar travel, focusing on propulsion technologies such as nuclear rockets, fusion, antimatter, and solar sails. The presentation emphasizes the importance of spreading life beyond Earth, with a mention of upcoming symposiums by the Interstellar Research Group to further explore these topics.

Insights

  • Interstellar travel poses immense challenges due to vast distances, with technologies like nuclear rockets and fusion offering potential solutions, but scaling and implementation hurdles remain.
  • Solar sails present a promising avenue for interstellar travel, with NASA developing increasingly larger sails like the Solar Cruiser, aiming to propel probes to speeds of 10-15% the speed of light using high-energy lasers alongside sunlight.

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Recent questions

  • What is the topic of the presentation?

    A Traveler's Guide to the Stars

  • How many exoplanets have been confirmed?

    Over 5,000

  • What is the specific impulse of chemical rockets?

    3 to 400 seconds

  • What is the potential trip time for a 1,000-year journey?

    Less than 1,000 years

  • What is the focus of the Interstellar Research Group?

    Advancing interstellar travel

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Summary

00:00

"Interstellar Travel: Challenges and Possibilities"

  • The speaker expresses disappointment at not being able to attend the Royal Institution in person due to events in Paris.
  • The speaker clarifies that their opinions are personal and not reflective of their employer, NASA.
  • The topic of the presentation is "A Traveler's Guide to the Stars," focusing on interstellar travel for the average person.
  • The speaker's expertise lies in advanced in-space propulsion, working on next-generation systems.
  • The speaker discusses the vast distances involved in interstellar travel, using the example of the local interstellar neighborhood.
  • The speaker shares personal experiences in Australia, highlighting the visibility of Alpha Centauri from the Southern Hemisphere.
  • The Les scale is introduced to provide a perspective on the distances within our solar system.
  • The speaker emphasizes the immense challenge of traveling to the nearest star, which is unimaginably far away.
  • The talk is based on known physics, discussing the possibility of interstellar travel to nearby stars but highlighting the engineering challenges.
  • Over 5,000 exoplanets have been confirmed since the 1990s, with estimates of 100 to 400 billion exoplanets in our galaxy alone.

13:14

"Rocket Technology for Interstellar Travel"

  • A 1,000-year trip time is considered long but not excessively so, with historical structures dating back over 1,000 years in various countries.
  • Launching a probe to another star today could potentially allow future civilizations to receive its transmissions if still around in 1,000 years.
  • Rockets work by expelling exhaust in one direction to propel the rocket in the opposite direction, based on principles of conservation of momentum and energy.
  • Chemical rockets, commonly used for space travel, are designed for thrust rather than efficiency due to Earth's gravity, with a specific impulse (ISP) of 3 to 400 seconds.
  • The rocket equation dictates that adding more propellant to increase thrust leads to diminishing returns due to increased mass, limiting chemical rockets to a trip time of about 50,000 years.
  • Electric rockets utilize electric and magnetic fields to accelerate ions for propulsion, offering higher efficiency with specific impulses in the thousands of seconds.
  • Nuclear rockets, using nuclear reactions to heat propellant, provide high thrust and an ISP of around 1,000 seconds, potentially reducing the need for excessive propellant in interplanetary travel.
  • Fusion, replicating the sun's energy production, could offer a greener and more efficient energy source if miniaturized for spacecraft propulsion, potentially reducing trip times to less than 1,000 years.
  • Nuclear pulse, exemplified by Project Orion, involves detonating small nuclear bombs underneath a spacecraft to propel it into space rapidly, offering high thrust and efficiency for large payloads.
  • While challenges exist in scaling fusion reactors and implementing nuclear pulse propulsion, these technologies hold promise for interstellar travel within reasonable timeframes.

26:55

"Revolutionizing Space Travel: Antimatter and Solar Sails"

  • Space propulsion experts discussed technologies for sending a probe beyond the solar system at a meeting.
  • Dr. Freeman Dyson, known for Project Orion, shared unauthorized test stories at the meeting.
  • Project Orion could reach 5% the speed of light but would harm the biosphere.
  • Antimatter rockets could revolutionize space travel by converting mass into energy.
  • Antimatter is produced in small quantities naturally and at CERN, but large-scale production is a challenge.
  • Antimatter annihilation releases energy and could power rockets for interstellar travel.
  • Solar sails use photons to propel spacecraft, offering a fuel-free propulsion method.
  • Solar sails have been tested in Earth orbit and interplanetary space, with sizes limited to spacecraft under 100 kilograms.
  • NASA has developed and tested various sizes of solar sails, with plans for larger sails like the Solar Cruiser.
  • The Solar Cruiser sail, composed of four quadrants, is 1,653 square meters and uses thin film solar sail material.

39:49

"Interstellar Travel: Challenges and Future Possibilities"

  • NanoSail-D was flown in 2010, measuring 10 square meters, leading to the development of NEA Scout and Advanced Composite Solar Sail System, nearly 100 square meters each.
  • Solar Cruiser, currently being built, will be 1,600 square meters, with scalability up to 10,000 square meters for interstellar travel.
  • For interstellar travel, a sail of a square kilometer is needed, requiring a material like graphene to be 15 to 20 times lighter than current sail materials.
  • High-energy lasers in space will be used alongside sunlight to propel sails to speeds of 10 to 15% the speed of light for interstellar travel.
  • The EMDrive, a controversial drive, and the Alcubierre Warp Drive, requiring negative mass, are discussed as speculative physics concepts.
  • A one-kilogram robotic probe traveling at 10% the speed of light could release energy equivalent to seven Hiroshima bombs upon impact with a planet.
  • The debate between sending people or robots for space exploration is discussed, with the conclusion that both will be utilized.
  • The moral imperative to spread life beyond Earth is emphasized to protect against potential extinction events like supervolcanoes or asteroid impacts.
  • The idea of spreading life beyond Earth is supported, with a suggestion to follow a Prime Directive-like approach to avoid interfering with existing life on other planets.
  • Challenges of interstellar travel beyond propulsion, including power, communication, life support, and terraforming, are highlighted as surmountable with effort.

52:46

"Interstellar Dreams: Solar Sails and Beyond"

  • The speaker is motivated by the belief that solar sails will facilitate interplanetary exploration, envisioning humans eventually traveling to other stars like Alpha Centauri.
  • At NASA, the speaker's career goal is to have their work acknowledged in the history of the first settlement on a planet orbiting a different star, emphasizing their desire to be a footnote in that narrative.
  • The Interstellar Research Group, dedicated to advancing interstellar travel through science, technology, ethics, and more, holds symposiums every two years, with the upcoming one scheduled for July in Montreal at McGill University, welcoming paper submissions and encouraging attendance for those interested in futuristic discussions.
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