(PhysOrg.com) — British space engineers working for a space company in Stevenage in England, have designed a “gravity tractor” spacecraft to deflect any asteroids threatening to collide with Earth. The announcement comes only weeks after an asteroid collision scar around the size of Earth was detected on Jupiter. Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Asteroid (2867) Steins. Image: ESA Citation: Spacecraft Could Save Earth from Asteroids (2009, September 4) retrieved 18 August 2019 from https://phys.org/news/2009-09-spacecraft-earth-asteroids.html A collision with an asteroid is a rare event, but scientists believe it is inevitable that sooner or later an asteroid will come close enough to be a real threat. In fact in 2004 an asteroid called Apophis caused alarm when scientists predicted there was a 1:37 chance of it hitting Earth in 2029, which is the greatest threat in recorded history. They later revised their figures but it could still be on course to collide in 2036. The US space agency, NASA estimates there are at least 1000 “potentially hazardous asteroids.”NASA is so concerned about the threat it has set up a monitoring program to track every space object that could be an asteroid on a collision course. They are so far tracking over 6,000 asteroids whose orbits bring them close to Earth, but there are an estimated 100,000 asteroids large enough to wipe out a city.A collision could be catastrophic, depending on how large the asteroid is and where it hits. A direct hit to a city by even a relatively small asteroid the size of a football field, for example, could completely destroy the city and kill millions of people. Many more could be killed by tsunamis triggered by the impact, and by dust and burning material thrown up into the atmosphere after the collision.The engineers, led by Dr Ralph Cordey, head of exploration and business at EADS Astrium, a British space company, have designed what they call a “gravity tractor”, a ten-tonne spacecraft around 100 feet long that could provide a practical way of averting a collision with Earth. The device would be launched as soon as an asteroid was found to be on course to crash into the planet, and would fly alongside it at a distance of about 160 feet away. The craft could divert an asteroid up to 430 yards in diameter, and an impact with an asteroid this size would release around 100,000 times the energy of the bomb dropped on Hiroshima in 1945.The gravity tractor is designed to draw the asteroid towards itself by exerting a small gravitational force on it. The spacecraft would then steer the asteroid away into an orbit away from Earth. The craft would use four ion thrusters, which are low energy and efficient, of the type commonly used on deep space probes. The ion thrusters enable the craft to adjust its position relative to the asteroid. The gravitational pull exerted by the asteroid would be enough to nudge the rock into a different, and less dangerous, trajectory.The process of steering the asteroid away from a collision course would take several years, with the craft changing the angle of trajectory by only a fraction of an inch over 15 years, but that is enough change to divert an asteroid. The spacecraft would need to be launched at least 15 (preferably 20) years before the predicted collision to give it time to adjust the asteroid’s trajectory away from Earth.The design team say the gravity tractor could be built fairly quickly with existing technologies, although a prototype has not yet been built. They have planned the details of the mission, and expect the cost could be shared by a number of governments if an asteroid on track to hit Earth was discovered, and international agreements would need to be drawn up.NASA published a paper earlier this year on the feasibility of using a gravity tractor for this purpose, and they concluded it could be extremely effective if there was enough warning. With scientists saying the asteroid Apophis could possibly be on a course to collide with Earth in 2036, perhaps we do have enough warning.© 2009 PhysOrg.com NASA Statement on Student Asteroid Calculations
(Phys.org) — Fullerenes were first discovered back in 1985 by a team of physicists vaporizing graphite in helium gas, one class of which, the buckminsterfullerene (C60) named after Buckminster Fuller and his geodesic domes, forms into spherical, hollow cages that resemble soccer balls. Since that time, a lot of study has been done on and with so named buckyballs, yet no one has been able to figure out how exactly they form. Now, new research by one of the original discoverers of fullerenes, Harold Kroto and his team at Florida State University moves closer to that goal in finding that buckyballs grow larger when exposed to vaporized carbon. The team has written a paper describing their observations and have had it published in the journal Nature Communications. Buckyballs… throwing astronomers a curve Quantum chemical modelling of growth processes. Image (c) Nature Communications, doi:10.1038/ncomms1853 Explore further Because of their similarity to graphene, sheets of one atom thick carbon atoms that form hexagonal patterns, researchers have wondered if fullerenes might come into being after first existing as simple sheets that somehow warp to the degree that they form into balls. Unfortunately, no one has yet been able to create the right set of circumstances that have allowed them to witness the actual birth of a fullerene structure, though they have found that they also exist in nature as well, specifically in the soot that comes from burning candles, and near red giant stars or supernovae.Using a Fourier transform ion cyclotron resonance mass spectrometer, Kroto and his team were able to analyze what happens when buckyballs come to exist in the same space as vaporized carbon, they grow larger. They found that small fullerenes grew to buckyball size, and buckyball sized fullerenes grew into larger balls by “eating” or absorbing carbon atoms into their structure. They also found that the original structure was maintained by atoms being shifted around during the absorption process.In learning more about how fullerenes are formed, and now how they grow, researchers are able to apply new evidence to help explain other natural phenomenon, such as how they come to exist in space in such large quantities such as is found with carbon stars and supernovae and why their distribution in the lab is so similar to what is found in the soot produced by a burning candle. More information: Closed network growth of fullerenes, Nature Communications 3, Article number: 855 doi:10.1038/ncomms1853AbstractTremendous advances in nanoscience have been made since the discovery of the fullerenes; however, the formation of these carbon-caged nanomaterials still remains a mystery. Here we reveal that fullerenes self-assemble through a closed network growth mechanism by incorporation of atomic carbon and C2. The growth processes have been elucidated through experiments that probe direct growth of fullerenes upon exposure to carbon vapour, analysed by state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry. Our results shed new light on the fundamental processes that govern self-assembly of carbon networks, and the processes that we reveal in this study of fullerene growth are likely be involved in the formation of other carbon nanostructures from carbon vapour, such as nanotubes and graphene. Further, the results should be of importance for illuminating astrophysical processes near carbon stars or supernovae that result in C60 formation throughout the Universe.via RSC Journal information: Nature Communications Citation: Team finds buckyballs grow larger by ‘eating’ vaporized carbon (2012, May 30) retrieved 18 August 2019 from https://phys.org/news/2012-05-team-buckyballs-larger-vaporized-carbon.html © 2012 Phys.Org This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
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