Here I collect links pertaining to NearEarthObjects and their possible collisions with Earth.

Sites

NASA asteroid and comet impact hazards

MIT's LINEAR asteroid search program

Near Earth Asteroid Tracking system

Uni.of Arizona's Spacewatch program

Lowell Observatory NEO Survey

Tunguska Home Page at the Physics dept. at the University of Bologna

U.K. NEO Information Centre

NASA JPL pages

Proceedings of the Planetary Defense Workshop at LLNL, May 22-26, 1995

Spaceguard

Simulations

• EarthShooter simulates the collision of an asteroid with the Earth, in a simple two-body treatment. It shows the effects of "gravitational focussing", and that for small approach speeds the Earth presents a larger effective cross section than its geometric cross section.
• NEO Simulator allows to study the effect of exploding an asteroid or trying to deflect it in order to avoid collision of the asteroid with Earth. This takes place in the gravitational sphere of influence of the Earth, and addresses what could be done in the very last moments.
• Comet Halley's Orbit in the Solar System is an application of the wonderful Applet OrbitViewer by O.Ajiki and R.Baalke to the comet Halley. It allows to view the positions of the planets at any time and to view their orbits from any angle.
• Asteroid 1997 XF11's Orbit in the Solar System
• Orbits and Travels in the Solar System uses Keplerian orbits to show how a body travels through the Solar System, such as a planet, asteroid, or comet. We can inspect the body's distance from Earth, and see how it could be detectable by its brightness or velocity. We can also launch a probe from Earth to intercept the body.
• Trip to Jupiter: Schedule departure and arrival is an extended version. It uses Keplerian orbits to compute the time windows available for travelling from the Earth to another body orbiting the Sun, such as a planet, asteroid, or comet. For these mission windows, it displays the various properties of the mission, such as departure and arrival speeds, orbital eccentricity and period. It thus allows to optimize an interplanetary space mission.
• Near Earth Objects are judged to be potential hazards to the Earth. This applet allows to show how such an object on collision course could be detected from Earth before the collision, and to estimate the effects of the impact on the Earth surface. We can also try to find the orbital trajectory for an intercepting mission.
• Hit and Deflect a Near Earth Object is an extension of the above applet: it also allows to find the launch windows for an intercept mission, and to estimate how much it would take to try to deflect the body sufficiently to avoid the collision with Earth.
• Decision map displays on a map of NEO diametre and the speed at its impact on Earth various data: the energy of the impact (to judge how severe the consequences of such an event would be). Then the time before collison at which the body could be detected, given a limiting visual magnitude. And the energy that would be required to cause a given deflection of the trajectory, depending on the time of launch and the speed of an interceptor. All calculations are done in a rather rough approximation, that the NEO approaches on a straight line at constant speed. This neglect of the effects of gravity by the Earth and by the Sun limits such a study to fast objects, but one can still get a rather good impression about the principal issues.

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