Sunday, July 17, 2022

Skyscraper-size asteroid will blaze past Earth in a close approach this Sunday

5:31 PM |

An asteroid the size of a 50-story skyscraper will zoom past Earth Sunday (July 17), making its closest approach to our planet in nearly 100 years.

The meaty space rock, dubbed 2022 KY4, will safely miss Earth by about 3.8 million miles (6.1 million kilometers), or more than 16 times the average distance between Earth and the moon, according to NASA. This is considerably farther afield than the asteroid 2022 NF, which came within 56,000 miles (90,000 km) — or about 23% the average distance between Earth and the moon — on July 7.

Asteroid 2022 KY4 is about 290 feet (88 meters) in diameter at its widest visible point and is traveling at an estimated 16,900 mph (27,000 km/h) — around eight times as fast as a speeding rifle bullet, according to NASA.

The space rock has made several close approaches to Earth before, most recently in 1959 and 1948. The asteroid won't make another close approach to our planet until May 2048, NASA calculated.

NASA and other space agencies closely monitor thousands of near-Earth objects like this one. Even if an asteroid's trajectory puts it millions of miles from our planet, there is an extremely slim chance that the asteroid's orbit could shift slightly after interacting with the gravity of a larger object, such as a planet; even such a tiny shift could potentially put an asteroid on a collision course with Earth on a future flyby.

As such, space agencies take planetary defense very seriously. In November 2021, NASA launched an asteroid-deflecting spacecraft called the Double Asteroid Redirection Test (DART), which will slam directly into the 525-foot-wide (160 m) asteroid Dimorphos in autumn 2022. The collision won't destroy the asteroid, but it may change the space rock's orbital path slightly, Live Science previously reported. The mission will help test the viability of asteroid deflection, should some future asteroid pose an imminent danger to our planet.

Originally published on Live Science.

Tags:Space & Astrophysics

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2 commenti:

Victor said...

Now it's completely clear that, as I have already noted being a PhD in astrophysics, more than once, the success of the DART mission as such can only be there if the laws of physics do not work...
The matter is that the near-Earth asteroids are rather loose pile of a multi-sized gravitationally bound meteoroids but not a monolithic rock. Such composition creates an almost insurmountable barrier to any type of «impulse» methods of their deflection. This barrier applies to both impacts and relatively low-powered surface or near-surface explosions (extremely-powered one is unacceptable due to a number of other known reasons). It is because a shock wave arising from an impact/explosive (together with material escaping) decays and dissipates fast enough, wasting all its energy on heating and redistribution of nearest different sized rock fragments.
Modern studies in which the impact modeling was carried out taking into account the real structure of asteroids, show that the momentum transfer during the impact decreases sharply with a decrease in cohesion between their individual rock fragments – see, for example: Raducan S.D, Jutzi M. Global-scale Reshaping and Resurfacing of Asteroids by Small-scale Impacts, with Applications to the DART and Hera Missions, The Planetary Science Journal, Volume 3, Number 6, p.128, 2022.

In addition, evidence from recent space missions to near-Earth asteroids (e.g., Ryugu and Bennu) suggests that their surface and internal cohesion is very weak – up to zero – see, for example: Walsh K.J. et al , Near-zero cohesion and loose packing of Bennu’s near subsurface revealed by spacecraft contact, Science Advances, 7 Jul 2022, Vol 8, Issue 27. DOI: 10.1126/sciadv.abm6229

Therefore, in result the momentum delivery to the asteroid as a whole will completely block, similarly to the perfectly inelastic collision.

Today the optimum way (most powerful push thrusting, scalability up to global-threat sizes and any type of hazardous bodies as well as low cost and environmental friendliness) is use of high-focused solar energy by an innovative type of concentrating collector - see: Vasylyev V. P., Deflection of Hazardous Near-Earth Objects by High Concentrated Sunlight and Adequate Design of Optical Collector, Earth, Moon, and Planets, Vol 110, Issue 1-2, pages 67–79 (2013),
as well as relevant section of the Wikipedia (“Asteroid impact avoidance - Use of focused solar energy”).

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