Question Humans 11th Successful Asteroid Impact Warning

[550W（sky·忆）]

China successfully warned of asteroid impact, so far no impact on Earth, what happens next depends on the latest news

 

[550W（sky·忆）]

Based on global observations compiled by the International Small Planet Center, the Purple Mountain Observatory predicts an entry time of 2024/12/03 16:15 UTC at 60.80°N, 118.98°E during the asteroid's approach. The results are comparable to those announced by the International Small Planet Center

 

[550W（sky·忆）]

Do we really need early warning of asteroid impacts? Is there a high probability that Earth will encounter an asteroid in space? If one day a successful warning of an impact on Earth, is it possible for us to proactively prevent it?Or destroy it

 

[billslugg]

The probability of an asteroid is very small but must be protected against. Only by knowing their exact orbits can we make plans. We have already demonstrated the changing of a rock's orbit by smashing a satellite into it. Now, it is only a matter of the engineering, cost and time. The more time we have, the bigger a rock we can move.

 

[Jim Franklin]

China successfully warned of asteroid impact, so far no impact on Earth, what happens next depends on the latest news

Sadly, it is like a terrorist trying to sneak a bomb onto a plane - we have to be observant and be successful 100% of the time, the terrorist, in this case asteroids, only have to be successful once by sneaking by us to be potentially catastrophic.

If we take a 100m nickel-iron asteroid lets look at details and damage.

• Object - 100m
• Density - 8000kg/m3
• Velocity at atemospheric entry - 25km/s
• Impact angle to surface - 45°
• Distance from impact - 10km

Now lets look at the effects

• Energy before atmospheric entry: 1.31x 10E18 Joules (3.13 x10E2 Megatons TNT)
• The average interval between impacts of this size somewhere on Earth during the last 4 billion years is approximately estimate to be 15,000 years, however, on the Moon these appear to occur at a rate of about every 500 years, which does indicate our crater rates for Earth are wrong.
• The projectile begins to break up at an altitude of 20.4 km (12.6 miles).
• The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at a velocity of 23.2 km/s (14.4 miles/s).
• The energy lost in the atmosphere is 1.86x 10E17 Joules (4.44 Megatons TNT).
• The impact energy is 1.12x 10E18 Joules (268 Megatons TNT).
• The broken projectile fragments strike the ground in an ellipse of dimension 391 m (1282 ft) by 276 m (906.3 ft).
• Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.
• Transient CraterDiameter: 2.79 km (1.73 miles)
• Transient Crater Depth: 986 m (3236 ft)
• Final CraterDiameter: 3.21 km (1.99 miles)
• Final Crater Depth: 420 m (1379 ft)
• The crater formed is a complex crater.
• The volume of the target melted or vaporized is 0.00707 km3 (0.00170 miles3).
• Roughly half the melt remains in the crater.
• Time for maximum radiation: 89.8 millisecondsafter impact
• Visible fireball radius: 2.07 km (1.29 miles)
• The fireball appears 47.1 times larger than the sun
• Thermal Exposure: 5.34 x 106 Joules/m2
• Duration of Irradiation: 27.0 seconds
• Radiant flux (relative to the sun): 198
• Effects of Thermal Radiation:
  • Clothing ignites
  • Much of the body suffers third degree burns
  • Newspaper ignites
  • Plywood flames
  • Deciduous trees ignite
  • Grass ignites
• The major seismic shaking will arrive approximately 2 secondsafter impact.
• Richter Scale Magnitude: 6.2
• Mercalli Scale Intensity at a distance of 10 km:
  • VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.
  • VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.
• The ejecta will arrive approximately 45.2 seconds after the impact.
• At 10km there is a fine dusting of ejecta with occasional larger fragments.
• Average Ejecta Thickness: 54.1 cm (21.3 inches)
• Mean Fragment Diameter: 8.74 m (28.66 ft)
• The air blast will arrive approximately 30.3 seconds after impact.
• Peak Overpressure: 273000 Pa = 2.73 bars = 38.7 psi
• Max wind velocity: 352 m/s (1154 ft/s)
• Sound Intensity: 109 dB (may cause ear pain)
• Damage Description: (at 10km)
  • Multistory wall-bearing buildings will collapse
  • Wood frame buildings will almost completely collapse.
  • Highway truss bridges will collapse.
  • Glass windows will shatter.
  • Up to 90 percent of trees blown down; remainder stripped of branches and leaves.

If such an impact landed occured on a major city, the death toll would be multiple millions. Even landing outside a city but within 10km, the death toll would still be around 250,000 plus.