metmike: Some really good comments under this article about the theories related to it. How important is this subject to earth's history and the future of humans?
The threat to life on this planet from another large asteroid impact is probably millions of times greater than that from climate change from burning fossil fuels.
This was my comment and why I carried this article here to have a discussion about the topic at the bottom:
"Using climate crisis alarmism/exaggeration tactics, can we speed up the Asteroid Impact Avoidance programs?
Instead of using flourishing polar bears as the global warming mascot.........use the moon as the Asteroid Impact mascot.
All those impact craters. Many like that are on our own planet!
Tell people that there are thousands of large asteroids out there and that history assures us that some of them will hit the earth eventually.
Wait...............that would be the entire truth and how would it be used similar to how twisting the beneficial gas, CO2 into pollution is done for political and financial gain?
Dang, I guess that's why we don't hear much about it (-:
One realm features a climate optimum on a greening planet with the best weather/climate for life in at least 1,000 years......which is massively contributing to the quality of lives and helping to support the nearly 8 billion people.
The other one features the potential extinguishing of billions of humans in a very brief period.
Guess which one most people are afraid of?"
The Minor Planet Center in Cambridge, Massachusetts has been cataloging the orbits of asteroids and comets since 1947. It has recently been joined by surveys that specialize in locating the near-Earth objects (NEO), many (as of early 2007) funded by NASA's Near Earth Object program office as part of their Spaceguard program. One of the best-known is LINEAR that began in 1996. By 2004 LINEAR was discovering tens of thousands of objects each year and accounting for 65% of all new asteroid detections. LINEAR uses two one-meter telescopes and one half-meter telescope based in New Mexico.
The Catalina Sky Survey (CSS) is conducted at the Steward Observatory's Catalina Station, located near Tucson, Arizona, in the United States. It uses two telescopes, a 1.5-meter (60-inch) f/2 telescope on the peak of Mount Lemmon, and a 68-cm (27-inch) f/1.7 Schmidt telescope near Mount Bigelow (both in the Tucson, Arizona area). In 2005, CSS became the most prolific NEO survey surpassing Lincoln Near-Earth Asteroid Research (LINEAR) in total number of NEOs and potentially hazardous asteroids discovered each year since. CSS discovered 310 NEOs in 2005, 396 in 2006, 466 in 2007, and in 2008 564 NEOs were found.
Spacewatch, which uses a 90 centimeter telescope sited at the Kitt Peak Observatory in Arizona, updated with automatic pointing, imaging, and analysis equipment to search the skies for intruders, was set up in 1980 by Tom Gehrels and Robert S. McMillan of the Lunar and Planetary Laboratory of the University of Arizona in Tucson, and is now being operated by McMillan. The Spacewatch project has acquired a 1.8 meter telescope, also at Kitt Peak, to hunt for NEOs, and has provided the old 90-centimeter telescope with an improved electronic imaging system with much greater resolution, improving its search capability.
Other near-Earth object tracking programs include Near-Earth Asteroid Tracking (NEAT), Lowell Observatory Near-Earth-Object Search (LONEOS), Campo Imperatore Near-Earth Object Survey (CINEOS), Japanese Spaceguard Association, and Asiago-DLR Asteroid Survey. Pan-STARRS completed telescope construction in 2010, and it is now actively observing.
For asteroids that are actually on track to hit Earth the predicted probability of impact continues to increase as more observations are made. This similar pattern makes it difficult to differentiate between asteroids that will only come close to Earth and those that will actually hit it. This in turn makes it difficult to decide when to raise an alarm as gaining more certainty takes time, which reduces time available to react to a predicted impact. However, raising the alarm too soon has the danger of causing a false alarm and creating a Boy Who Cried Wolf effect if the asteroid in fact misses Earth.
Various collision avoidance techniques have different trade-offs with respect to metrics such as overall performance, cost, failure risks, operations, and technology readiness. There are various methods for changing the course of an asteroid/comet.These can be differentiated by various types of attributes such as the type of mitigation (deflection or fragmentation), energy source (kinetic, electromagnetic, gravitational, solar/thermal, or nuclear), and approach strategy (interception, rendezvous, or remote station).
Strategies fall into two basic sets: Fragmentation and delay. Fragmentation concentrates on rendering the impactor harmless by fragmenting it and scattering the fragments so that they miss the Earth or are small enough to burn up in the atmosphere. Delay exploits the fact that both the Earth and the impactor are in orbit. An impact occurs when both reach the same point in space at the same time, or more correctly when some point on Earth's surface intersects the impactor's orbit when the impactor arrives. Since the Earth is approximately 12,750 km in diameter and moves at approx. 30 km per second in its orbit, it travels a distance of one planetary diameter in about 425 seconds, or slightly over seven minutes. Delaying, or advancing the impactor's arrival by times of this magnitude can, depending on the exact geometry of the impact, cause it to miss the Earth.
Collision avoidance strategies can also be seen as either direct, or indirect and in how rapidly they transfer energy to the object. The direct methods, such as nuclear explosives, or kinetic impactors, rapidly intercept the bolide's path. Direct methods are preferred because they are generally less costly in time and money. Their effects may be immediate, thus saving precious time. These methods would work for short-notice and long-notice threats, and are most effective against solid objects that can be directly pushed, but in the case of kinetic impactors, they are not very effective against large loosely aggregated rubble piles. Indirect methods, such as gravity tractors, attaching rockets or mass drivers, are much slower. They require traveling to the object, changing course up to 180 degrees for space rendezvous, and then taking much more time to change the asteroid's path just enough so it will miss Earth.
Many NEOs are thought to be "flying rubble piles" only loosely held together by gravity, and a typical spacecraft sized kinetic-impactor deflection attempt might just break up the object or fragment it without sufficiently adjusting its course. If an asteroid breaks into fragments, any fragment larger than 35 meters across would not burn up in the atmosphere and itself could impact Earth. Tracking the thousands of buckshot-like fragments that could result from such an explosion would be a very daunting task, although fragmentation would be preferable to doing nothing and allowing the originally larger rubble body, which is analogous to a shot and wax slug, to impact the Earth.
In a similar manner to the earlier pipes filled with a partial pressure of helium, as used in the Ivy Mike test of 1952, the 1954 Castle Bravo test was likewise heavily instrumented with line-of-sight (LOS) pipes, to better define and quantify the timing and energies of the x-rays and neutrons produced by these early thermonuclear devices. One of the outcomes of this diagnostic work resulted in this graphic depiction of the transport of energetic x-ray and neutrons through a vacuum line, some 2.3 km long, whereupon it heated solid matter at the "station 1200" blockhouse and thus generated a secondary fireball.
Initiating a nuclear explosive device above, on, or slightly beneath, the surface of a threatening celestial body is a potential deflection option, with the optimal detonation height dependent upon the composition and size of the object. It does not require the entire NEO to be vaporized to mitigate an impact threat. In the case of an inbound threat from a "rubble pile," the stand off, or detonation height above the surface configuration, has been put forth as a means to prevent the potential fracturing of the rubble pile. The energetic neutrons and soft X-rays released by the detonation, which do not appreciably penetrate matter, are converted into thermal heat upon encountering the object's surface matter, ablatively vaporizing all line of sight exposed surface areas of the object to a shallow depth, turning the surface material it heats up into ejecta, and, analogous to the ejecta from a chemical rocket engine exhaust, changing the velocity, or "nudging", the object off course by the reaction, following Newton's third law, with ejecta going one way and the object being propelled in the other. Depending on the energy of the explosive device, the resulting rocket exhaust effect, created by the high velocity of the asteroid's vaporized mass ejecta, coupled with the object's small reduction in mass, would produce enough of a change in the object's orbit to make it miss the Earth.
A Hypervelocity Asteroid Mitigation Mission for Emergency Response (HAMMER) has been proposed
If the object is very large but is still a loosely-held-together rubble pile, a solution is to detonate one or a series of nuclear explosive devices alongside the asteroid, at a 20-meter (66 ft) or greater stand-off height above its surface, so as not to fracture the potentially loosely-held-together object. Providing that this stand-off strategy was done far enough in advance, the force from a sufficient number of nuclear blasts would alter the object's trajectory enough to avoid an impact, according to computer simulations and experimental evidence from meteorites exposed to the thermal X-ray pulses of the Z-machine
This early Asteroid Redirect Mission artist's impression is suggestive of another method of changing a large threatening celestial body's orbit by capturing relatively smaller celestial objects and using those, and not the usually proposed small bits of spacecraft, as the means of creating a powerful kinetic impact, or alternatively, a stronger faster acting gravitational tractor, as some low-density asteroids such as 253 Mathilde can dissipate impact energy.
In 2011, the director of the Asteroid Deflection Research Center at Iowa State University, Dr. Bong Wie (who had published kinetic impactor deflection studies previously), began to study strategies that could deal with 50-to-500-metre-diameter (200–1,600 ft) objects when the time to Earth impact was less than one year. He concluded that to provide the required energy, a nuclear explosion or other event that could deliver the same power, are the only methods that can work against a very large asteroid within these time constraints.
This work resulted in the creation of a conceptual Hypervelocity Asteroid Intercept Vehicle (HAIV), which combines a kinetic impactor to create an initial crater for a follow-up subsurface nuclear detonation within that initial crater, which would generate a high degree of efficiency in the conversion of the nuclear energy that is released in the detonation into propulsion energy to the asteroid.
A similar proposal would use a surface-detonating nuclear device in place of the kinetic impactor to create the initial crater, then using the crater as a rocket nozzle to channel succeeding nuclear detonations.
Who knows whether, when a comet shall approach this globe to destroy it...men will not tear rocks from their foundations by means of steam, and hurl mountains, as the giants are said to have done, against the flaming mass?
~ Lord Byron
Following the 1994 Shoemaker-Levy 9 comet impacts with Jupiter, Edward Teller proposed, to a collective of U.S. and Russian ex-Cold War weapons designers in a 1995 planetary defense workshop meeting at Lawrence Livermore National Laboratory (LLNL), that they collaborate to design a one-gigaton nuclear explosive device, which would be equivalent to the kinetic energy of a one-kilometer-diameter (0.62 mi) asteroid. The theoretical one-gigaton device would weigh about 25–30 tons, light enough to be lifted on the Energia rocket. It could be used to instantaneously vaporize a one-kilometre (0.62 mi) asteroid, divert the paths of ELE-class asteroids (greater than 10 kilometres or 6.2 miles in diameter) within short notice of a few months. With one year of notice, and at an interception location no closer than Jupiter, it could also deal with the even rarer short period comets that can come out of the Kuiper belt and transit past Earth orbit within two years.[clarification needed] For comets of this class, with a maximum estimated diameter of 100 kilometers (62 mi), Chiron served as the hypothetical threat
An April 2014 GAO report notes that the NNSA is retaining canned sub assemblies (CSAs—nuclear secondary stages) in an indeterminate state pending a senior-level government evaluation of their use in planetary defense against earthbound asteroids." In its FY2015 budget request, the NNSA noted that the nine-megaton B53 component disassembly was "delayed", leading some observers to conclude they might be the warhead CSAs being retained for potential planetary defense purposes.[failed verification]
The use of nuclear explosive devices is an international issue and will need to be addressed[according to whom?] by the United Nations Committee on the Peaceful Uses of Outer Space. The 1996 Comprehensive Nuclear-Test-Ban Treaty technically bans nuclear weapons in space. However, it is unlikely that a nuclear explosive device, fuzed to be detonated only upon interception with a threatening celestial object, with the sole intent of preventing that celestial body from impacting Earth would be regarded as an un-peaceful use of space, or that the explosive device sent to mitigate an Earth impact, explicitly designed to prevent harm to come to life, would fall under the classification of a "weapon".[9