Ex-News Junkie
Massaging the numbers a bit
Sat Oct 28, 2017 11:34am
2001:1970:5c22:6100:9896:4ab1:7ae4:8cb8

Relativistic Centrifuge with Magnetic Levitation
RPM = 28628071
RPS = 477135
Radius = 100 meters
Rim speed = c-1 = 299792457 m/s
Lorentz Factor = 12243
Centripetal acceleration = 898,755,172,740,968 m/s2
G-forces = 9.16.E+13 gees
Radial field gradient to levitate objects inside centrifuge = 8.23192.E+08 Teslas (via magnetohydrodynamic dynamo)

Outside Ship vs. Inside Centrifuge Distance-Time Comparisons
Distance to Alpha Centauri = 4.132E+16 meters
Starship velocity = 16260 m/s (same as New Horizons spacecraft)
Outside world travel time = 80,581 years
Outside world travel time = 4,201,729 weeks
Inside centrifuge travel time = 6.582 years
Inside centrifuge travel time = 343 weeks
Inside distance traveled per week = 1.204E+14 meters
Inside apparent velocity = 66 percent light speed

Crew Rotations
Outside world servicing time per crew = 15 years
Number of 15-year crew stints per 80581 year travel time = 5372
Total manpower = 80,581
Inside centrifuge time while crew outside = 10.73 hours
Inside centrifuge R&R time per crew = 6.580 years
Combined outside & inside centrifuge time per crew = 21.580 years
Total crew servicing workload = 1,738,978 person-years
Total crew person-meals = 1,904,180,865
Example: Boxes of Mac & Cheese (2 meals each) = 952,090,433 boxes, size per box 3.5 cm x 9cm x 18.5 cm, total storage volume 554,831 cubic meters (82.17-meter cube)

What this Achieves
Although a relativistic centrifuge is a formidable technological hurdle, it is not necessarily ruled out. With this capability an interstellar ship could travel at a relatively low speed, aka "slow boat" to the stars, while at the same time yielding many advantages:

- low propellant requirements for conventional ion rocket or other high-efficiency propulsion

- ability to accelerate, decelerate, maneuver & rendezvous with Oort Cloud objects along the way to replenish fuel & other material resources

- continuous maintenance is achieved for entire 80,581-year journey

- no crew member ages more than 22 years

- benefits of relativity, i.e. time dilation, are obtained without expending wasteful amounts of propellant via the rocket equation

- energy used for the relativistic centrifuge can be accumulated prior to departure, is largely conserved during the journey, and can be recovered "regeneratively" after arriving at Alpha Centauri to be used for other purposes

- with precise diamagnetic control over g-forces inside the relativistic centrifuge a 1-gee habitat can be maintained

- a "slow boat" has lesser shielding requirements for micrometeorite impacts & radiation: a simple Whipple Shield should suffice

- 18-year old adults who consent to making the journey would be less than 40-years old when they arrive - not too old to start a family

- if Alpha Centauri is too hostile, the ship can turn around and return to Sol, or continue on to another star system, and arrive in less than a human lifetime


  • Radius = 100 meters Tangential velocity = c-1 = 299792457 m/s Vt/c = 0.99999999666 Lorentz Factor = 12243 As before the centrifuge is spinning with a rim speed of c-1 m/s, that is just 1 m/s slower... more
    • Massaging the numbers a bit — Ex-News Junkie, Sat Oct 28 11:34am
      • Starfield Effects at 66 percent of the speed of lightEx-News Junkie, Sat Oct 28 4:10pm
        The starship would be a "slow boat" to the stars, with an actual speed of only 16 km/sec. But time would run very slowly inside the relativistic centrifuge. If there were a window (more likely a... more
        • Making things a bit more difficultEx-News Junkie, Sun Oct 29 8:07am
          Time dilation would vary along the radius of the centrifuge. The design calls for a rim speed of c-1 m/s to give a Lorentz factor of 12243. However, objects stored in the centrifuge are not... more
          • CorrectionEx-News Junkie, Sun Oct 29 8:24am
            200,000 km is 2.3-times the diameter of a geosynchronous orbit around Earth, and nowhere near the size of the Moon's orbit. My bad! This size starship is actually in about the same ball park as many... more
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                • Slow Boat versus Hot Rod to the starsEx-News Junkie, Sat Nov 4 11:52pm
                  Slow Boat Hot Rod Limiting Factor ok X propellant ok X shielding ok X refuel/resupply ok ok maintenance ok ok geometry & structural stability X ok g-forces X ok freedom of movement of passengers and... more
                  • Starship Size ComparisonEx-News Junkie, Mon Nov 6 6:17pm
                    Below is a comparison of the sizes of a Space Elevator Ring, and a Starship Ring, neatly sandwiched between the Earth and the Moon's orbit. Image is to scale in units of km.
                    • Some professional stuffEx-News Junkie, Sat Nov 11 5:40pm
                      Science Magazine Abstract ... "We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The... more
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