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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. The space elevator faces many obstacles: Lightning strikes Atomic oxygen
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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
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 Introduction
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
Surface Area • The space elevator’s 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
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 Meteors and Mircometeors
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
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
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
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 Comet’s 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 Albedo’s and Magnitude
Detection Programs • Many programs exist to search for Near Earth Objects • NASA’s Near and MIT’s LINEAR programs are used to protect the Earth from these deadly asteroids • Currently, they are used to find NEO’s 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
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
Ribbon is about a meter by 100,000km Made up of 1000’s 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 Ribbon Design
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 lift’s command center
Heat Energy Field • It’s 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
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
Works Cited • Works Cited • Baalke, Ron. "Arecibo and Micrometeors." 28 May 1997. July 2006 <www.meteorobs.org/maillist/msg04686,html>. • "Bond Albedo, Near Earth Asteroids, Radar Astronomy." Wikipedia. 15 Aug. 2006. 15 Aug. 2006 <www.wikipedia.org>. • Briley, Mike. "Micrometeorites." University of Wisconsin. July 2006 <www.astro.wsu.edu/wortney/astro/html/meteor.html>. • 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 <www.tulane.edu>. • Yeomans, Don. "Absolute Magnitude (H)." NASA. Aug. 2006. NASA. July 2006 <www.neo.jpl.nasa.gov/glossary/h.html>. • Yeomans, Don. "NEA Discovery Statistics." NASA. Aug. 2006. July 2006 <www.neo.jpl.nasa.gov/stats>.
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!