Interstellar Travel: Another Look

"Tau Zero Takes Aim at Interstellar Propulsion"
Paul Gilster, Space News, Discovery News (January 10, 2011)

"Guest contributor Paul Gilster is a founding member of the Tau Zero Foundation, a non-profit group of scientists dedicated to the incremental advancement of interstellar spaceflight. Project Icarus, one of the Foundation's key initiatives, has reached a major milestone and Paul shares this exciting project with Discovery News. Paul also maintains Centauri Dreams, the news forum of the Tau Zero Foundation.

"Marc Millis steeples his fingers, leaning back in his chair to ponder a question from one of the practitioner scientists of the Tau Zero Foundation.

"He's in Austin, Texas, for a session devoted to roughing-out ideas and organization plans for the young organization with an ambitious goal: Build a practical groundwork for interstellar flight within sound, peer-reviewed physics; establish the basics that will one day lead -- whether in decades or centuries -- to technologies that can take us to the stars.

"The blackboard is littered with his organizational chart, arrows connecting boxes, people attached to study groups. Solar sails, fusion, ion drives -- they're all up for discussion...."

The article focuses, rather tightly, on Project Icarus, one of the older efforts to design a practical interstellar probe. And no, Project Icarus isn't run by crackpots.

What's exciting about Project Icarus and similar endeavors is that, unlike Alcubierre's warp drive, they focus on propulsion technologies which are either available now, in development, or which might become practical in my childrens' lifetimes.

The Lemming's guess is that exploration of space around other stars will follow the same pattern that we see in exploration of the Solar system: astronomical observations; followed up by robot spaceships; with the rare-to-occasional expedition carrying people.

But that's just a guess.

A huge issue with travel between stars is that they're so far apart: around four or five light years, on average, in our neighborhood. Between the limited amount of energy we can use today, travel to the nearest star might, optimistically, take centuries. (NASA (July 1, 1995))

Then, as propulsion systems get more advanced, we run into another barrier: literally. The space between stars is almost a perfect vacuum. Almost, but not quite. There's an average of one hydrogen atom in every cubic centimeter. (Gene Smith, Center for Astrophysics & Space Sciences, UC San Diego)

Something traveling fast enough to get to, say, Alpha Centauri, less than five light years away, in 40 years would have to be going at around an eighth the speed of light. At those speeds, the object would be running into those atoms - very fast. At those speeds, the electrons, neutrons, and protons of the the hydrogen nuclei would act like cosmic rays, when they hit the leading edge of that speedy object.

Which isn't to say that interstellar travel that doesn't take centuries is impossible. Just that it's something we don't have the technology for.

Today.

Technology to send people into orbit wasn't around when Robert Goddard startled his neighbors in Massachusetts: and that's another topic.

Related posts:

• "Interstellar Space Probe: Thirty Years Later"
  (May 9, 2010)
• "Warp Speed Kills? Let's Say It's an Engineering Challenge"
  (March 11, 2010)
• "Interstellar Travel: Difficult, yes; Impossible; No - NASA"
  (April 30, 2008)
• "Warp Drive Might Not Be Stable: Physicists Take Another look at Alcubierre's Work"
  (June 12, 2009)
• "Why 'It Can't Be Done' is a Dangerous Statement"
  (January 24, 2008)

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More:

• "How to Build an Antimatter Rocket for Interstellar Missions" (pdf)
  Systems Level Considerations in Designing Advanced Propulsion Technology Vehicles
  Robert H. Frisbee, Jet Propulsion Laboratory, California Institute of Technology, via NASA (July 2003)
• "Humanity in Space: The Next Few Centuries"

More, at other websites:

• "Emerging Possibilities for Space Propulsion Breakthroughs"
  NASA (July 1, 1995)
• "Breakthrough Propulsion Physics" NASA - including
  • Quantum Vacuum Energy
  • Transient Inertia
  • Lifters, Biefeld-Brown, Asymmetrical Capacitors, etc.
  • Space Drives(Step 1: defining the problem)
  • Faster Than Light (general relativity approach)
• "Early Days of Rocket and Aeronautics"
  Marshall Space Flight Center - including
  • Timeline of Rocket History)
  • Notes on Robert Goddard)
  • MSFC Goddard Rocket Replica Project)
  • Notes on Hermann Oberth)
  • Photograph of Hermann Oberth)
  • Notes on the National Advisory Committee for Aeronautics)
  • Photograph of NACA Pilot)