How Astronomers Missed the Massive Asteroid That Just Whizzed Past Earth

[Winston]

How Astronomers Missed the Massive Asteroid That Just Whizzed Past Earth
26 Jul 2019

https://www.livescience.com/66043-giant-asteroid-flyby-surprises-astronomers.html

A large asteroid just whizzed past our planet — and astronomers weren't expecting it.

Ranging in size from 187 to 427 feet (57 to 130 meters) wide, the space rock named 2019 OK snuck up on us Thursday morning (July 25). It swung as close as 45,000 miles (73,000 kilometers) from Earth, what one astronomer told The Washington Post was "uncomfortably close.".

If the asteroid had actually collided with Earth, the crash would have caused devastating damage, Michael Brown, an associate professor in astronomy at Monash University in Australia, wrote in The Conversation.

Astronomers in Brazil and the United States separately discovered 2019 OK a couple of days ago, but it's surprise visit was only announced a couple of hours before it passed by. "The lack of warning shows how quickly potentially dangerous asteroids can sneak up on us," Brown wrote. And though this asteroid "is not a threat to Earth right now," other such near-Earth asteroids can be.

Different one:

Astronomers Spotted a Car-Size Asteroid Just Hours Before Impact
27 Jul 2019

https://www.livescience.com/65810-car-size-asteroid-hits-earth.html

Astronomers discovered a car-size asteroid hours before it slammed into Earth and burned up in the atmosphere this past weekend, news sources report.

Scientists in Hawaii initially spotted the asteroid, named 2019 MO, on Saturday (June 22). Soon after, the heavenly traveler broke apart in large fireball as it hit the atmosphere about 240 miles (380 kilometers) south of San Juan, Puerto Rico, according to the University of Hawaii.

This is only the fourth time in history that scientists have spotted an asteroid so close to impact. The other three detections all occurred within the past 11 years, including 2008 TC3, 2014 AA and 2018 LA, which landed as a meteorite in southern Africa just 7 hours after it was noticed by scientists.

Unlike 2018 LA, Earth's latest visitor was harmless and didn't make it to the ground. But the asteroid, 13 feet (4 meters) long, still made a spectacular fireball that was equivalent to about 6,000 tons of exploding TNT, according to the Center for Near Earth Object Studies (CNEOS), which is run by the Jet Propulsion Lab in Pasadena, California.

 

[Wallace]

Yup, pretty scary stuff. I always wonder what effect spotting it earlier would have? Allow time to duck and cover? Possibly just panic? How long would it take to evacuate San Juan and where would they go? Sometimes it's better to just not know...

 

[ewomack]

I've read at least one book in the last few years that claimed that we've discovered so many NEOs that we really don't need to worry, but I then keep hearing about surprises such as the one above.

The B612 foundation strives to map all known NEOs and even to construct a vehicle to send threatening asteroids veering away from the earth should we have enough notice. But we clearly had very little notice in the story above. Certainly not enough to send a rocket to intercept it. It just shows that we're still not prepared for something hurtling through space.

 

[Winston]

Diameter: 57 to 130 meters [20 meters for Chelyabinsk meteor/ite]
Velocity: 24.5 km/s [19.16 km/s for Chelyabinsk meteor/ite]

Assumed:

Stony composition
Entry at compromise case 45 degree angle

Calculations via:

https://www.purdue.edu/impactearth/

57 meter size: begins to breakup at an altitude of 60,200 meters (198,000 feet); bursts into a cloud of fragments at an altitude of 5730 meters (18,800 feet); energy of the airburst is 19.7 megatons; No crater is formed, although large fragments may strike the surface; 21.7 Megatons total energy [0.4 to 0.5 Megatons for Chelyabinsk meteor/ite]

130 meter size: crater 2.61 km (1.62 miles) in diameter, 556 meters (1820 feet) deep; 258 Megatons total energy; 102 Megatons impact energy

 

[Winston]

Using a nuclear weapons effect calculator:

https://www.nuclearsecrecy.com/nukemap/

Not perfect, but probably in the ballpark.

57 meter size; 19.7 Megaton airburst at 5,730 meters (18,800 feet):

Fireball radius: 4.14 km (2.57 miles)

Maximum size of the nuclear fireball; relevance to lived effects depends on height of detonation. If it touches the ground, the amount of radioactive fallout is significantly increased.

Air blast radius (20 psi): 5.88 km (3.65 miles)

At 20 psi overpressure, heavily built concrete buildings are severely damaged or demolished; fatalities approach 100%. Often used as a standard benchmark for heavy damage in cities.

Air blast radius (5 psi): 12.4 km (7.7 miles)

At 5 psi overpressure, most residential buildings collapse, injuries are universal, fatalities are widespread. Often used as a standard benchmark for medium damage in cities.

Air blast radius (1 psi): 31.8 km (19.67 miles)

At a around 1 psi overpressure, glass windows can be expected to break. This can cause many injuries in a surrounding population who comes to a window after seeing the flash of a nuclear explosion (which travels faster than the pressure wave). Often used as a standard benchmark for light damage in cities.

Thermal radiation radius (3rd degree burns): 38.2 km (23.7 miles)

Third degree burns extend throughout the layers of skin, and are often painless because they destroy the pain nerves. They can cause severe scarring or disablement, and can require amputation. 100% probability for 3rd degree burns at this yield is 13.2 cal/cm2.

130 meter size; limited to 100 Megatons [full-yield Czar Bomba] instead of 102 Megatons since that's the limit of the simulator; 100 Megaton surface burst:

Fireball radius: 7.92 km (4.9 miles)

Maximum size of the nuclear fireball; relevance to lived effects depends on height of detonation. If it touches the ground, the amount of radioactive fallout is significantly increased.

Air blast radius (20 psi): 10.1 km (6.3 miles)

At 20 psi overpressure, heavily built concrete buildings are severely damaged or demolished; fatalities approach 100%. Often used as a standard benchmark for heavy damage in cities.

Air blast radius (5 psi): 21.2 km (13.2 miles)

At 5 psi overpressure, most residential buildings collapse, injuries are universal, fatalities are widespread. Often used as a standard benchmark for medium damage in cities.

Air blast radius (1 psi): 54.6 km (33.9 miles)

At a around 1 psi overpressure, glass windows can be expected to break. This can cause many injuries in a surrounding population who comes to a window after seeing the flash of a nuclear explosion (which travels faster than the pressure wave). Often used as a standard benchmark for light damage in cities.

Thermal radiation radius (3rd degree burns): 64.2 km (39.8 miles)

Third degree burns extend throughout the layers of skin, and are often painless because they destroy the pain nerves. They can cause severe scarring or disablement, and can require amputation. 100% probability for 3rd degree burns at this yield is 13.9 cal/cm2.

 

[Winston]

I've read at least one book in the last few years that claimed that we've discovered so many NEOs that we really don't need to worry, but I then keep hearing about surprises such as the one above.

The B612 foundation strives to map all known NEOs and even to construct a vehicle to send threatening asteroids veering away from the earth should we have enough notice. But we clearly had very little notice in the story above. Certainly not enough to send a rocket to intercept it. It just shows that we're still not prepared for something hurtling through space.

Unfortunately, an organization like B612 to promote detection of smaller asteroids shouldn't even be necessary when a fraction of what we spend (waste) annually on the ISS would do the job well.

From B612:

"The combination of LSST, Pan-STARRS, Catalina Sky Survey, and NEOCam together can bring the global inventory of Near Earth Asteroids down to about 140 meters in size, which is a major improvement over our catalog today. Eventually, we will want to extend our surveys down to asteroids capable of destroying an entire city (40 meters or larger), but that will require a future leap in technology."

As can be seen by the calculations made about 2019 OK, even 140 meters isn't adequate. Odds are, the smaller the asteroid, the more of them there will be floating around out there:

 

[Wallace]

Thank you all for the info: What do we do with it other than marvel?

 

[Winston]

Thank you all for the info: What do we do with it other than marvel?

Just fun stuff to know.

 

[Wallace]

Just fun stuff to know.

Agreed. Keep watching the sky.

 

[ewomack]

Oh well. I guess I'll watch too...

 

[Hobie1dog]

It will be just like the Hollywood movie when it does happen ( don't remember the name of it, as I didn't watch it), somebody will know the name of it.

 

[ewomack]

I think it was "2012." I actually didn't see it. Others I know watched it for me and I experienced it vicariously through them. Based on what I heard, that may be the best way to see it.

 

[Hobie1dog]

That was some serious special effects

The movies were
Meteor-1979
Deep Impact- 1998
Post Impact- 2004
Meteor Apocalypse-2010

The movie clip above was about the planet self-destructing.

 

[mrwalsh85]

It will be just like the Hollywood movie when it does happen ( don't remember the name of it, as I didn't watch it), somebody will know the name of it.

Armageddon.

 

[Winston]

Here are what I think should be the new, clearly stated and defined goals for NASA. The first is about the survival of the human race or, at least, the saving of potentially millions of lives and the second is about the most important question: are we alone?:

1. Planetary protection ASAP: detection of threats down to at least 40 meter size and on-standby deflection methods and related hardware (relatively easy and cheap)
2. Robotic search for life or past life in the solar system followed by manned missions once the most promising site or sites are found (expensive).

A (failed) private effort like this should not be necessary:

Sentinel Space Telescope

https://en.wikipedia.org/wiki/Sentinel_Space_Telescope

As of April 2013, B612 was attempting to raise approximately $450 million in total to fund the total development and launch cost of Sentinel, at a rate of some $30 to $40 million per year.[5] That funding profile excludes the advertised 2018 launch date.

After NASA terminated their $30 million funding agreement with the B612 Foundation in October 2015 and the private fundraising did not achieve its goals, the Foundation eventually opted for an alternative approach using a constellation of much smaller spacecraft which is under study as of June 2017. NASA/JPL's NEOCam has been proposed instead.

NOVA | Asteroid: Doomsday or Payday? [HD]

 

[Peartree]

This is another of those areas that's tough to find. Not because we can't agree that it's important (though I'm sure Congress would argue that as well), but because we can't agree on who should pay for it. The rest of the world seems to assume that we should pay for it and warn them of any danger. But Congress doesn't want to pay for something that other countries will use, even if it saves their bacon as well. (sigh)

 

[shreadvector]

Yup, pretty scary stuff. I always wonder what effect spotting it earlier would have? Allow time to duck and cover? Possibly just panic? How long would it take to evacuate San Juan and where would they go? Sometimes it's better to just not know...

They cut the last few seconds....darn.