Asteroid 2018 LA (ZLAF9B2): superfireball

Astronomers have just discovered an asteroid with an identification (while at the time) ZLAF9B2. Its diameter is between 2 to 5 meters if considered perfect ball-shaped. Surprisingly, this asteroid will pass very close to our Earth. It is just a geostationary satellite orbit (36,000 kilometers above the Earth's surface). Taking into account the value of the orbital uncertainty based on the amount of data collected at the time, then there is the potential of this mini asteroid to fall to Earth. Or technically it will get into the Earth's atmosphere and turn into a superhero meteor (super fireball). And even more surprising, the intersection of the asteroid trajectory with a height of 120 kilometers above the parts of the earth spans across parts of Indonesia. If a celestial body touches the height limit, it will almost certainly enter the atmosphere with all its consequences.

Asteroid 2018 LA

^{2008 TC3,wikimedia}

The International Astronomical Union (IA) labeled this ZLAF9B2 asteroid as a 2008 LA asteroid. The Sky Catalyst Sky Survey system is armed with a powerful telescope and semi-automatic identification system at the Lemmon Mountain Observatory in the Catalina Mountains area of Arizona (United States) that first detected it on June 2, 2018. Armed with only 12 observed data obtained during only 3.5 hours from various directions, some properties of 2018 asteroid LA was revealed. It becomes part of the Apollo-class asteroid, a group of near-Earth asteroids that roam between the orbits of Venus and Mars so have a chance to cut Earth's orbit. It encircles the Sun with a period of 1.61 years and the slope of the orbit (inclination) is only 4º.

From the start, it was discovered that the movement of the 2018 LA asteroid looks different than any other newly discovered asteroids in near-Earth environments. Asteroids are enshrined as lines with forecasts +18 magnitude (64 times dimmer than Pluto). So it's not a dim light. This impressive impression of asteroid 2018 LA moves fast enough and may be very close to Earth. Further analysis confirms this, asteroid 2018 LA is going to pass very close and even potentially big fall to Earth, with probability fall to 85%.

Asteroid 2018 LA potentially fall in Indonesia. The forecast point of the fall ranges from the island of Irian in the east to the island of Sumba, to then drove across the Indonesian Ocean. Predicted as passing south of Java island, this asteroid has an overall magnitude of about +11 to +12. Obviously, if we could direct the telescope to him it would be very difficult to detect amid the colonization of the Moonlight rays and the severity of light pollution for the night sky.

^maxpixel

Less than 1.5 hours after it was predicted to penetrate the Indonesian sky, a Dhiraj S in Gaborone (Botswana) reported to the American Meteor Society (AMS) about the appearance of a super fireball. He managed to capture it in the image (photo) with a time of 2-second exposure. Her image shows a typical bright line of meteors along about 10º. Surprisingly, but unrecorded, a moment later this meteor evolved into a yellowish super fireball, a marker containing a lot of Sodium, with an estimated visual magnitude of -27 at its peak. That means he was lighter than the Sun!
Other reports come from neighboring countries. Barend Swanepoel, owner of a farm in Ottosdal (South Africa) reported his closed-circuit camera system (CCTV) recorded unusual sky events. Detected a celestial body that moves through the light. At its peak, it is so bright, equal to or exceeding the brightness of the Sun, when it is close to the horizon.

^maxpixel

The analysis shows that if the potential fall trajectory that exists in Indonesia is developed westward, then the extension will meet exactly with the border of Botswana and South Africa. No doubt, the super fireball is indeed an asteroid 2018 LA that falls to Earth. Here is a video recording, also from CCTV in Ottosdal but sourced from Mellisa Delport on another farm:

Impact

In this attempt to detect the event of the fall of celestial bodies to Earth no longer rely solely on visual visibility. But it also utilizes invisible wave signals or even inaudible mankind. This is what the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), an institution under the umbrella of the United Nations (UN) enforced to oversee international treaties ban all nuclear tests in both spaces, atmospheric, earth-shaped, shallow underground, underground deep ground, shallow underwater and deep underwater. The CTBTO, however, is also capable of sniffing various atmospheric nuclear-event-related atmospheric explosion-releasing events. Especially with two types of flagship instrument, which is a micro barometer instrument to capture infrasonic wave signals and seismometer radios to record seismic signals.

That's what the micro barometer instilled at the IS47 station located in southern Africa. The infrasonic wave was strong enough to be recorded at this station at some time after the recorded super fireball in Ottosdal. Peter Brown's analysis, an astronomer specializing in meteors, suggests that it is equivalent to releasing 0.3 to 0.5 kilotons of TNT.
From this data can be estimated how big asteroid 2018 LA. From its orbit, we know that this asteroid has a free velocity (vinf) of 15.8 km/sec (56,900 kilometers / h) so that when it enters the Earth's atmosphere it has a relative velocity (vgeo) of 19.4 km/sec (69,700 kilometers / h). With a kinetic energy range between 0.3 to 0.5 kilotons of TNT, the diameter of 2018 asteroid LA is between 1.7 to 2 meters. While the mass between 9.5 to 15.5 tons. These diameters and masses are obtained with the assumption that the 2018 LA asteroid has a composition identical to that of a chondritic meteorite (density of 3.7 grams / cm3).

^{Chondrite,wikipedia}

Further analysis, by utilizing the equations and models collected by Collins et al (2005), shows some interesting things. For example, before entering the Earth's atmosphere this asteroid has a potential energy of between 0.4 to 0.7 kilotons of TNT. Once entering Earth's atmosphere, its speed slows down due to friction with the air molecules that simultaneously produce ram pressure. This pressure breaks down the asteroids as well as greatly slow it down from a height of 40 kilometers from the earth's surface. This is an airburst event (like an explosion-in-air) that makes the super fireball kinetic energy released into the surrounding air. This energy transfer manifests in, for one, acoustic energy. This is recorded by a micro barometer radical at IS47 station.

With an energy of only 0.3 to 0.5 kilotons of TNT, the fall of the 2018 LA asteroid has no real physical impact on the underside of the earth below. Because the shock wave produced is still weak enough to cause damage. Moreover, the heat rays are much weaker again. Therefore the fall of the 2018 LA asteroid does not have a real impact on the situation on the earth's paras which became the target point.

The third

Asteroid 2018 LA is the third asteroid to be found before falling to kiss the Earth in astronomy history kiwari. The two previous asteroids are TC3 asteroid 2008 and asteroid 2014 AA.

^{Ground track and probable explosion point in midair of the asteroid 2008 TC3 which entered earth's atmosphere and exploded over Sudan on 2008-10-06..wikimedia}

Asteroid 2008 TC3 (diameter 4 meters, mass 83 tons) was found on October 6, 2008, or 20 hours before the fall. It is found in a position 500,000 kilometers from our Earth and observed by no less than 26 observatories, resulting in no less than 800 valuable observational data. Asteroid members of this Earth-grade asteroid Apollo class enter Earth's atmosphere also above Africa, precisely above the border of Sudan and Egypt. Its kinetic energy is measured between 1.1 to 2.1 kilotons of TNT. It produces a very large meteorite, up to no less than 600 pieces, known as the Almahatta Sitta meteorite.

While the 2014 AA asteroid (3-meter diameter, 38 tons mass) was discovered on January 1, 2014, in 23 hours before it crashed. It is also found at a distance of 500,000 kilometers from our Earth, but it is rarely successful to observe it. This asteroid is also a member of the Apollo-type near-Earth asteroid. It enters the Earth's atmosphere above the Atlantic Ocean with a kinetic energy of about 4 kilotons of TNT. Because it falls amid the vastness of the ocean, not a single meteorite is found.

The successful detection of these three asteroids shows the astronomical progress in identifying the threat of a collision of celestial bodies. Although this ability is still limited effectiveness and still much to be improved. These limitations still produce a large gap in the detection of all asteroids near the Earth even though they will pass very close or even fall to Earth.

Several times this big gap has a complicated effect. The actual example is the Chelyabinsk event, when undetected asteroids (though ~ 17 meters in diameter with a mass of 10,000 tons) undergo airburst over Siberia (Russia) on February 13, 2013. The kinetic energy of 500 kilotons of TNT is released, producing shock waves and a mild heat wave that destroys the city of Chelyabinsk and its surroundings. Thousands of people were injured and thousands of buildings damaged by a total loss of up to millions of dollars. Even as other nameless asteroids, with a diameter of ~ 10 meters, experience airburst over Bone, South Sulawesi (Indonesia) on October 8, 2009, releasing kinetic 60 kiloton TNT. Similarly, other asteroids without naming, 1-meter diameter, pounding the Earth's surface on September 15, 2007. The collision occurred on the high plains of the Titicaca lakeside and formed a large 13.5-meter (crater) hole at the edge of Caracas village (Peru ).