[kellyhound]

On Feb. 15, 2013 at 9:20 a.m. local time, residents of the city of Chelyabinsk, Russia, witnessed something few humans ever have: an asteroid exploding in the atmosphere.

The event was well-documented, almost by accident. Dashboard cameras in cars were and are very popular and many of these cameras captured video recordings of the meteor (the streak of light across the sky) and the great flash that came when the asteroid exploded.

The asteroid responsible for the event was about 20 meters (66 feet) in diameter, and entered the atmosphere at a relatively shallow angle with a speed relative to Earth of about 19 kilometers per second (69,000 kilometers per hour or 42,690 miles per hour).

When it hit the Earth’s atmosphere it began to burn up and then exploded about 30 kilometers (less than 19 miles) above the surface.

The explosion created a flash that was briefly brighter than the Sun and a shockwave that is estimated to have released the same amount of energy as 500 kilotons of TNT, which is around 30 times more energy than the atomic bomb detonated at Hiroshima.

The explosion happened high enough off the ground that its energy was mostly absorbed into the atmosphere. If it had happened lower, or if the asteroid had hit the ground intact, the damage could have been unlike anything in human history.

The meteor was incredibly heavy, with an estimated initial mass of 12,000 to 13,000 metric tons (approx. 26 to 28 million pounds). That's heavier as the Eiffel Tower f.i.

Around 78% of the meteor’s mass evaporated during its high-speed fall due to extreme friction and heat.

Only about 0.03% to 0.05% of the original weight actually reached the ground as solid meteorites.

The single heaviest fragment recovered was pulled from Lake Chebarkul and weighed 654 kg (1,442 lbs).

The meteorite was classified as an LL5 ordinary chondrite, which is the most common type of stony meteorite found on Earth. The LL stands for Low total iron, Low metal. It contained only about 10% iron and nickel, which is much less than other meteorite types.

The composition was mainly silicate minerals like olivine and pyroxene. Scientists found shock veins (dark streaks) throughout the rock. These were caused by previous collisions in space millions of years before it hit Earth. The rock itself was approximately 4.45 billion years old, nearly as old as the solar system itself.

The explosion created a shockwave that traveled through the atmosphere and reached the ground, damaging 7,200 buildings across 6 cities and sending 1,500 people to local hospitals and clinics with injuries.

Most of the injuries were caused by curiosity; people saw the bright flash and went to their windows to look outside.

The shockwave, traveling at a slower speed, arrived later and shattered the windows, injuring people with flying glass.

The most unsettling thing about the Chelyabinsk event is that nobody saw it coming. The asteroid wasn’t detected until it was already hurtling through Earth’s atmosphere, in large part because it came from the direction of the Sun and was hidden by its glare.

The total property damage was estimated at approximately 1 billion rubles, which converted to roughly $33 million USD at the time.

A notable instance of structural failure was the collapse of about 600 square meters of a roof at a local zinc factory.

Some witnesses reported skin or retinal burns from the intense ultraviolet radiation of the fireball, which was briefly 30 times brighter than the sun.

Scientists estimated that if the meteor would have hit the ground at full weight it would have created a crater roughly 500 to 600 meters (about 2,000 ft) wide and over 100 meters deep.

Anything within a few kilometers of the impact site would have been completely vaporized or leveled by the sheer kinetic energy.

Instead of just a bright flash in the sky, a ground impact would have created a massive fireball, causing intense heat and fires for miles around.

The strike would have triggered a localized earthquake with a magnitude of approximately 4.0 to 5.0, shaking buildings across the entire region.

The meteor entered at a shallow angle (about 18 degrees). This means it spent more time traveling through the thickest part of the atmosphere, which acted like a wall of air that eventually crushed the rock into pieces and that was their luck.

[kellyhound]

The biggest lesson from Chelyabinsk was that we cannot see meteors coming from the direction of the Sun.

So NASA is currently building the NEO Surveyor, a space telescope specifically designed to sit between Earth and the Sun. The NEO Surveyor will be stationed at the Sun-Earth L1 Lagrange point, a location of gravitational stability approximately 1.5 million kilometers (about 1 million miles) away from Earth.

It is currently in the final design and fabrication phase, targeting a launch in 2027 or 2028. It will use infrared sensors to find "dark" asteroids that ground telescopes miss.

In 2022 NASA successfully crashed a spacecraft into the asteroid Dimorphos, the DART mission, to see if we could nudge it off course. It worked better than expected.

The European Space Agency launched the Hera mission in October 2024. It is currently traveling to the same asteroid to perform a "crime scene investigation" and measure the impact crater in detail.

Hera is scheduled to reach the Didymos binary asteroid system in November 2026. The spacecraft is in its cruise phase. It successfully completed a Mars flyby on March 12, 2025, using the planet's gravity to gain velocity for its final trek.

Hera uses "self-driving" technology to navigate safely around the low-gravity asteroids without constant commands from Earth.

The mission carries two shoebox-sized satellites, Milani and Juventas, which will be deployed upon arrival to conduct radar soundings and surface mineral mapping.

Instruments include the Asteroid Framing Camera (AFC) for visual mapping and the HyperScout-H imager for mineralogical data.


The ESA is also developing a mission specifically to address meteors coming from the blind spot of the Sun. It is called NEOMIR (Near-Earth Object Mission in the InfraRed).

The spacecraft will also orbit the L1 Lagrange point, situated between the Sun and Earth.

It will use an infrared telescope to detect the heat signatures of asteroids, which are not drowned out by sunlight like visible light is.

It is designed to detect asteroids 20 meters and larger at least three weeks before a potential impact. NEOMIR is intended to complement NASA's NEO Surveyor mission as NASA's mission focuses on larger asteroids (over 140 meters)

NEOMIR is planned for launch in the early 2030s on an Ariane 6-2 rocket.

ESA has also studied softer ways to shoot at asteroids, such as using an Ion Beam. A spacecraft would hover near the asteroid and fire a continuous stream of ions (plasma) at it. This acts like a virtual tow truck, slowly pushing the asteroid without ever touching it.

[Mr.NoCredit]

I wondered if there would be a sonic boom and was not disappointed.

[houseoftechno]

Originally Posted by Mr.NoCredit ↗

I wondered if there would be a sonic boom and was not disappointed.

Thunder is a form of sonic boom and it can only be heard for about 10 miles. Chelyabinsk Meteor exploded at a 19 mile elevation, so I would bet there was no sound.

[Mr.NoCredit]

Originally Posted by houseoftechno ↗

Thunder is a form of sonic boom and it can only be heard for about 10 miles. Chelyabinsk Meteor exploded at a 19 mile elevation, so I would bet there was no sound.

At 3 minutes 57 seconds there’s a sonic boom that breaks windows and triggers car alarms in the area the person was filming from. You can hear the glass breaking and crashing. That wasn’t thunder.

[kellyhound]

Originally Posted by houseoftechno ↗

Thunder is a form of sonic boom and it can only be heard for about 10 miles. Chelyabinsk Meteor exploded at a 19 mile elevation, so I would bet there was no sound.

The meteor released energy equivalent to 500 kilotons of TNT. Lightning thunder average 0,00024 kiloton TNT.

An explosion of a meteor that size creates a powerful supersonic shock wave that can travel much further through the atmosphere than the sound of a standard lightning strike.

Also the explosion also produced a low frequency infrasound waves that were detected as far away as antarctica and traveled around the globe twice.

[houseoftechno]

Originally Posted by Mr.NoCredit ↗

At 3 minutes 57 seconds there’s a sonic boom that breaks windows and triggers car alarms in the area the person was filming from. You can hear the glass breaking and crashing. That wasn’t thunder.

I think I had stopped viewing the vid just prior to those massive booms!

That was damned impressive!