Protecting the Space Elevator: Space Debris

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Protecting the Space Elevator Space Debris

• Gabriel V. Cummings- Union Hill High School
• Department of Mechanical and Aerospace
  Engineering
• Rutgers University 98 Brett Road, Piscataway, NJ
  08854
• August 16, 2006

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Introduction

• The space elevator faces many obstacles
• Lightning strikes
• Atomic oxygen
• Induced oscillations
• Strong winds
• Meteor impacts

• Most severe problem Meteor strikes
• Could destroy single or multiple Carbon nanotube
  fibers
• Many larger than the 10-40 micron diameter of
  each fiber
• Complete elevator failure
• Loss of billions of research money

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Presentation Objective

• Discuss the threat of meteors hitting space
  elevator
• Talk about impact probability and surface area
• Propose various meteor detection systems
• Present ideal design for ribbon
• Discuss solutions for protecting the structure

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Surface Area

• The space elevators total surface area is about
  210km2
• The 999 space intervals between fibers account
  for almost 95 of area
• Area is only 10km2 without the spaces
• Very small in comparison to Earth
  (509,600,000km2)
• (Surface Area space elevator/Earth)
• 1/2,500,000 at 210km2
• 1/50,000,000 at 10km2

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Meteors and Mircometeors

• Nearly 300 Million meteors hit earth everyday
• About 105 Billion meteors strike Earth each year
• Almost 40 meteors a meter or larger enter the
  atmosphere a year
• Larger sizes are far less frequent but are more
  dangerous
• They are easier to detect because of size

• Nearly all meteors that impact the Earth are of a
  microscopic size
• 1 micro gram in weight
• The fastest micrometeors have as much energy in
  them as a 22 caliber bullet
• Very hard to detect, because of their microscopic
  size and high velocity
• If they come at an angle, it could destroy more
  than one fiber

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Artificial Satellites

• About 2,500 working and nonfunctioning satellites
  orbit the planet
• In total, there are over 8,000 pieces of
  artificial debris
• They are bound to strike the space elevator
  because of their orbits
• Tracking them is important
• Base of elevator should have ability to move in
  order to avoid a collision

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Radar

• Powerful radars could detect objects as small as
  1cm or less
• Until recently, radar only picked up meteors as
  noise
• The Arecibo observatory uses a 430 megahertz
  detection system to record micro meteorites as a
  velocity
• It is one of the only systems currently available
  with the ability to track micro meteors
• Could detect objects of nearly every size

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Satellites

• Satellites can be used to monitor space for any
  debris coming towards the elevator
• Provide a rough estimate on their distance and
  amount of time before an impact
• Better then earth based telescopes since their
  observations are not distorted by the atmosphere
• Increasing the number of observational satellites
  is a must for safeguarding the elevator

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Albedos and Magnitude

• Albedo is the ratio of the light reflected by an
  object over the amount of light that is absorbed
  by it
• it is measured from 0-1, zero is very dull and
  one is very bright
• Comets are about 0.6 and asteroids are near
  0.05-0.25

• Magnitude calculates the size range of an object
• H represents magnitude
• The scale ranges from 3.0 (670-1490km) to 30
  (3-6m)
• When Albedo's and Magnitude are combined to give
  an approximation of a projectiles size

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Detection Programs

• Many programs exist to search for Near Earth
  Objects
• NASAs Near and MITs LINEAR programs are used to
  protect the Earth from these deadly asteroids
• Currently, they are used to find NEOs larger
  then 1km
• In order to benefit the space elevator as well,
  the search range would have to be decreased
• More geared for larger objects

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Impact Probability
Size of Meteor Earth Impacts per year Space Elevator Impacts
1 micron 105 Billion 2163
1mm 1,050,000 1 every 50 yrs.
1 m 40 1 every 62,500 yrs.
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Space Elevator Headquarters

• Bases would analyze accumulating detection data
• It would come from NASA, radars, satellites, and
  other programs
• Determines the severity of an impact
• Proposes appropriate action
• Control center at the foot of the space elevator

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Ribbon Design

• Ribbon is about a meter by 100,000km
• Made up of 1000s of Carbon nanotube fibers 10-40
  microns in diameter
• To strengthen the overall design, two cross
  section fibers of 10-20 microns
• These would run every 100 meters

• From 500-1700km, double the width of the fibers,
  since this is the range where most meteors are
  located
• This would allow the ribbon to handle more
  strikes
• Also increases the critical size of a meteor
  hitting the space elevator

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Armed Satellites

• Each of them is responsible for a certain area
  around the elevator
• Armed with lasers
• Would destroy oncoming meteors before they become
  a hazard
• Never to be pointed towards the elevator or the
  Earth
• Only act under the control of the space lifts
  command center

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Heat Energy Field

• Its a very futuristic technology, possibly
  taking years to develop
• It would surround the entire structure, using a
  solar power energy source
• This is possible since Carbon nanotubes are good
  conductors of heat
• This energy would disintegrate any micro meteors
  before they get close to the space elevator
• Similar to the meteors burning up in the
  Mesosphere

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Conclusion

• I discussed the threat space debris had on the
  space elevator
• adequate detection and protection systems
• Impact Probability
• Surface Area ratios
• And lastly, the idea that the space elevator is a
  realistic goal for the future

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Works Cited

• Works Cited
• Baalke, Ron. "Arecibo and Micrometeors." 28 May
  1997. July 2006 ltwww.meteorobs.org/maillist/msg046
  86,htmlgt.
• "Bond Albedo, Near Earth Asteroids, Radar
  Astronomy." Wikipedia. 15 Aug. 2006. 15 Aug. 2006
  ltwww.wikipedia.orggt.
• Briley, Mike. "Micrometeorites." University of
  Wisconsin. July 2006 ltwww.astro.wsu.edu/wortney/as
  tro/html/meteor.htmlgt.
• Edwards, Bradley C., and Eric A. Westling. The
  Space Elevator a Revolutionary Earth-to-Space
  Transportation System. New York, 2002.
• Nelson, Stephen A. "Meteorites, Impacts, and Mass
  Extinction." 20 Apr. 2006. Tulane University.
  July 2006 ltwww.tulane.edugt.
• Yeomans, Don. "Absolute Magnitude (H)." NASA.
  Aug. 2006. NASA. July 2006 ltwww.neo.jpl.nasa.gov/g
  lossary/h.htmlgt.
• Yeomans, Don. "NEA Discovery Statistics." NASA.
  Aug. 2006. July 2006 ltwww.neo.jpl.nasa.gov/statsgt.
  

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Acknowledgements

• First and foremost, I would like to thank
  Professor Haym Benaroya for allowing me to
  conduct my research with him, and for showing me
  the importance of the space elevator
• Yuriy Gulik, for all of his help with the
  computer technology for my project
• Dan, Josh, Sergey, and Adaleena for keeping me
  entertained while I was conducting my research
• And to everyone else who helped make this
  presentation possible, Thank You!