Potential Disaster from Space

Have you ever seen an asteroid "fall" from the sky? Or holding and rocking outer space rocks? Or maybe tracing the crater due to an asteroid blow?

Thousands of asteroids inhabit space around the Earth. Among them, there is a potential threat to survival when hit the Earth with a very dramatic. The 1980s show that major changes in our biosphere may result from a 10 km asteroid or comet impact. This collision is one of the ends of the asteroid history or comet. Near-Earth asteroid studies are more likely to be performed than comets that can only be observed in the short span of time, ie when they appear as they approach the sun.

The Impulse Trail of the Earth

Large craters measuring 200 km in Chicxulub Yucatan-Mexican peninsula "is believed to be the result of a massive asteroid 65 million years ago that caused global extinctions including dinosaurs. Two large 85-km craters on the Chesapeake-Virginia coast and 100 km in 35-million-year-old Popigai-Siberia are thought to have led to large-scale climate change. Several expert groups (Raup and Sepkoski in 1984 and 1986, Rampino and Caldeira in 1993) collected crater data from spaceships to examine the interval of a dramatic collision on Earth. They found that these dramatic collisions occur every 26-31 million years.

^{An animation showing the impact, and subsequent crater formation (University of Arizona, Space Imagery Center).,wikipedia}

Collisions with smaller forces are more common. A very famous example is the gigantic fireball explosion that occurred in Tunguska-Siberia in 1908, resulting in local damage of 200 km2. This fireball is due to the heat of friction asteroids or comets in the atmosphere and exploded at a height of dozens to tens of km from the surface of the Earth.

The results of Morrison's 1994 study show a link between the size of the asteroid against the time-lapse of the collision. The results show a collision with the energy of Hiroshima atomic bomb can occur every year, while asteroids with a size of 50 m can hit Earth every century. Given more than half the face of the Earth is the oceans, the chances of targeting a blow are certainly bigger. This collision can cause a tsunami with a force of 10 to 40 times greater than the earthquake-tsunami. Sweeping sea waves on the beach can reach a height of more than 100 m (Morrison et al in 1994). Meanwhile, with the same leverage force, the damage caused by the tsunami is much greater than the collision damage that occurred in the mainland.

Earth Scouting Asteroids

In 2004, three asteroids measuring several dozen meters passed and nearly hit Earth at less than a tenth of Earth-Moon distance (38,440 km). These three new asteroids were discovered as they approached and crossed between the Earth and the Moon. When it hit Earth, the damage it caused could be greater than the Hiroshima atomic bomb. Every two years a small asteroid measuring several dozen meters passes as close to half the Earth-Moon distance. Unfortunately, in general, their arrival is rarely detected.

The world's astronomy community is well aware of this space threat, and therefore makes an agreement on its criteria. Asteroids with a size of more than 150 m passing against the Earth to as close as 0.05 astronomical units (AU), or approximately 19.5 times the Earth-Moon distance, are categorized as potentially hazardous Asteroids (PHA). This does not mean that the asteroid will actually hit Earth.

The list of PHAs from the beginning of the year to the first half of November 2005 issued by NASA and the Minor Planet Center (MPC) shows that up to now a dozen PHAs have crossed near Earth. There are 287 PHAs that have been and will approach the Earth from 2005 to 2050. These calculations suggest that from 2027 to 2029 there are three asteroids that will pass between Earth-Moon. The three asteroids are 1999 AN10 on August 7, 2007, 2001 WN5 on June 26, 2028, and Apophis on April 13, 2029. Their orbital motions need to be examined and examined more thoroughly in order to obtain more accurate orbital motion. In relation to these results, the distribution of the size and speed-across of PHAs by 2050. The larger the size and speed, the greater the potential damage it can cause when it hits the Earth.

Asteroid Mitigation Assault Efforts

The near-Earth asteroid survey to determine its orbital motion is the first step for all mitigation scenarios. This survey is naturally an international joint collaboration because all the places on Earth can be the target of a blow. Some major countries have even set up specific bodies that specifically handle survey and mitigation of asteroid blows.

Quite a lot of mitigation procedures were proposed by experts, for example by Ahrens and Harris in 1992. But basically there are two mitigation procedures:

1. Transfer of Asteroid Orbit. This procedure is good if we have a long waiting time (several decades) before the asteroid hit will happen. This waiting time is used to build various equipment used to divert the orbit of an asteroid so as not to hit Earth. The orbital redirection is done by providing momentum through a certain mechanism so that the asteroid's orbit changes in the order of the decade. This procedure is effective for small objects of less than 500 m, and the risk of rupture or destruction of asteroids is also low. However, making the necessary equipment can be costly and complex equipment is required.
2. Asteroid Destruction. This procedure can be taken when the waiting time is short, less than a decade. Suitable for relatively large asteroids (more than 500 m). Equipment can be easily and quickly made, ie by preparing a nuclear detonator. But caution is required when the destruction of it because it could be asteroid fragments post-destruction still endanger Earth. In addition, social and political considerations require that a launch carrying this nuclear detonator equipment should not fail.

Waste Space

No less potential threat to the near-Earth asteroids, spacecraft wastes for four decades spread as loose debris floating in near-Earth space. This waste density is generally located in three locations, namely: above the "low orbit" equator to a height of 2000 km, semi-stationary orbit at an altitude of 20,200 km, and geostationary orbit at an altitude of 35,788 km. This waste is very much in low orbit and may contain some harmful substances such as radioactive. This waste in addition to potentially damaging satellites and spacecraft that are still active, also spread the threat because it keeps staking the Earth in the human age range, thousands of years, or perhaps even up to millions of years.

There are three standard NASA waste disposal procedures implemented since 1995:

1. "Burn" the trash when it enters the atmosphere. This process must be strictly enforced to achieve a chance of failure under 1: 10,000 death risk.
2. "Park" space junk at a certain height. There are four garbage "parking" areas, namely: in the region between low or semi-stationary orbits, the region between the semi-stationary and geostationary orbits, the region above the geostationary orbit, and in the cruising of the heliocentric orbit.
3. Collect the garbage as soon as the mission is over and move it from the active orbital area. It is intended not to disturb the satellite or the active rides of the orbiting range.

The annual meeting of the UN Committee on Peace in Vienna, Austria in mid-June 2005 discussed the draft guidelines for space waste mitigation. The proposing countries include America, Japan, India and Western European countries. Representatives from other countries with ESA European observers and the ESA's Space Agency are also present.

Attention to Disaster from Space

It is interesting to note that the report of a committee dealing with natural disasters finance under the US National Research Agency of 1999 did not include a space disaster as part of its work object. This could be because there was no space disaster that happened that year. Generally, a disaster from space is rare, but high potential damage.

Attention to this type of disaster gave birth to the sky patrol program. These patrols can jointly be conducted by astronomical enthusiasts (amateurs) and professional astronomers. Cooperation like this has worked well in developed countries. It is vital that the speed of disseminating information on new object discoveries around Earth. Armed with this information, the observation of the new object can be confirmed and forwarded by amateur or professional astronomers in other parts of the world. Thus, we can be better prepared for the possibility of disaster from space, which in turn can reduce the level of fatality that occurs.

Exploration is not only in the crater due to an asteroid impact, but also by patrolling the sky areas. Who knows there are spies that appear from the darkness is darting toward Earth, whether it is asteroids or junk space junk. Thanks!

BEST REGARDS @irza

Refence :

https://www.space.com/34070-earth-vulnerable-to-major-asteroid-strike.html
https://www.smithsonianmag.com/science-nature/how-threat-getting-hit-asteroid-could-spur-international-collaboration-180961543/
http://www.physics.org/article-questions.asp?id=97
https://www.space.com/51-asteroids-formation-discovery-and-exploration.html
https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question11.html
https://www.newscientist.com/article/2127788-earths-greatest-hits-six-of-the-biggest-meteorites-in-history/
https://www.popularmechanics.com/space/a17822/the-asteroid-hunters/
https://www.jpl.nasa.gov/news/news.php?feature=7042
https://news.nationalgeographic.com/news/2015/01/150126-starstruck-asteroid-flyby-astronomy/
https://www.inverse.com/article/37659-what-is-the-number-of-deadly-undiscovered-asteroids
https://www2.jpl.nasa.gov/sl9/back2.html
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