What if an asteroid was about to hit Earth? Scientists ponder question

A Nasamosaic image of asteroid Bennu, composed of 12 PolyCam images
A Nasamosaic image of asteroid Bennu, composed of 12 PolyCam images

Here's a hypothetical: a telescope detects an asteroid between 100 and 300 meters in diameter racing through our solar system at 14 kilometers per second, 57 million kilometers from Earth.

Astronomers estimate a one percent risk the will collide with our planet on April 27, 2027. What should we do?

It's this potentially catastrophic scenario that 300 astronomers, scientists, engineers and emergency experts are applying their collective minds to this week in a Washington suburb, the fourth such international effort since 2013.

"We have to make sure people understand this is not about Hollywood," said NASA Administrator Jim Bridenstine as he opened the sixth International Planetary Defense Conference at the University of Maryland's campus in College Park.

Countries represented include China, France, Germany, Israel, Italy, Russia and the United States.

The idea that the planet Earth may one day have to defend itself against an asteroid used to elicit what experts call a "giggle factor."

But a meteor that blew up in the atmosphere over Russia on February 15, 2013, helped put an end to the sneers.

On that morning, a 65-foot (20-meter) asteroid appear out of nowhere over the southern Urals, exploding 14 miles (23 kilometers) above the town of Chelyabinsk with such force that it shattered the windows of thousands of buildings.

A thousand people were injured by the shards.

But "the positive aspect of Chelyabinsk is that it made the public aware, it made the political decision makers aware," Detlef Koschny, co-manager of the Planetary Defence Office of the European Space Agency (ESA) told AFP.

A meteorite trail is seen above a residential apartment block in the Urals city of Chelyabinsk, on February 15, 2013
A meteorite trail is seen above a residential apartment block in the Urals city of Chelyabinsk, on February 15, 2013

How many?

Only those asteroids whose orbit around our Sun brings them within 31 million miles of our planet—defined as "near Earth"—are of interest.

Astronomers are finding new ones each day: more than 700 so far this year, for a total of 20,001, said Lindley Johnson of NASA's Planetary Defense Coordination Office, which was created in 2016.

Among the most risky is a rock named 2000SG344: 165 feet in diameter, with a one in 2,096 chance in striking the Earth within a hundred years, according to the ESA.

The majority are very small, but 942 are more than 0.6 miles across, estimates astronomer Alan Harris.

The scientist told an audience that some large ones are probably still out there: "A fair fraction of the biggest ones are hiding... basically parked behind the Sun."

They are found mainly by two US telescopes, one in Arizona and the other in Hawaii.

The ESA has built a telescope for this purpose in Spain and is planning others in Chile and Sicily.

Many astronomers are demanding a space telescope because terrestrial telescopes are unable to detect objects on the other side of the Sun.

A view of the facade of a local paint and varnish plant damaged by a shockwave from a meteor in the Urals city of Chelyabinsk on
A view of the facade of a local paint and varnish plant damaged by a shockwave from a meteor in the Urals city of Chelyabinsk on February 15, 2013

Deflecting an asteroid

This week's exercise seeks to simulate global response to a catastrophic meteorite. The first step is aiming telescopes at the threat to precisely calculate its speed and trajectory, following rough initial estimates.

Then it boils down to two choices: try to deflect the object, or evacuate.

If it is less than 165 feet, the international consensus is to evacuate the threatened region. According to Koschny, it is possible to predict the country it will strike two weeks ahead. Days away from impact, it can be narrowed down to within hundreds of kilometers.

What about bigger objects? Trying to nuke them to smithereens like in the movie Armageddon would be bad idea, because it could just create smaller but still dangerous pieces.

The plan, instead, is to launch a device toward the asteroid to divert its trajectory—like a cosmic bumper car.

NASA plans to test this idea out on a real asteroid 492 feet across, in 2022, with the Double Asteroid Redirection Test (DART) mission.

One issue that remains is politics, says Romana Kofler, of the United Nations Office for Outer Space Affairs.

"Who would be the decision making authority?" she asked. "The consensus was to leave this aspect out."

The United Nations Security Council would likely be convened, but it's an open question as to whether rich countries would finance an operation if they themselves weren't in the sights of 2000SG344 or another celestial rock.

Explore further

The day the asteroid might hit

© 2019 AFP

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Apr 30, 2019
Well, all the religious houses of worship would be overflowing with hasty believers praying the incoming rock will fall on whomsoever of their neighbors they siriusly hate!

Apr 30, 2019
nukes work, you don't even need big ones. deep penetrating warheads can break down an asteroid to a pile of rubble which burns up in the atmosphere and does far less harm. that simple.

nukes do work. don't listen to the rubbish you hear about in the so called 'science news'. just go to youtube , lookup up the 1950's videos on underground testing of megaton size nukes. even a pure iron crystal 300 meters accross would be obliterated. the real issue is the timing.

if the nuke is too big and detonated too close to earth you get a big neutron flux high in the atmospher or in space, so you then have a sattelite catastrophe, for non hardened sattelites , and wrose, you may get ions lighting up and disabling earths grid. at least you'll get some nice auroras. there is no other reliable way of stopping asteroid with current technology.

the real threat to cities and civilization is man himself ....not asteroids. not global warming, warmongering and endlessly overconsuming human beings.

Apr 30, 2019
Yes Space is the correct place for nuclear reactors and nuclear bombs. Way more utility, way less risk.

May 01, 2019
? Anonym481968 ?
Is that you ponyboy?

Just a teeny little ol' quibble with your ass-umption of how how useful nukes can be expected to work in Outer Space.

The test explosions were buried under tonnage of rocks, within the Earth's one-gee field. The Russians in particular have tried to move quantities of earth using nukes.

The results were expensive failures as warheads are spectacularly inefficient method. Considering the costs, before & after, polluting ground-water & security considerations?
Just ain't worth spending the rubles.

Nukes produce low output of work-energy.
& the bigger they are?
The more embarrassing the fizzle!
The missile guidance systems would be specialized to intercept an asteroid.

The best usage would be early interception, with a proximity radar-fuse, to nudge the rock into missing the Earth.

So going to take extensive early-warning systems.
Expensive big rockets with the delta-v to carry the warhead to interception.

Who pays for it?
Who controls it?

May 01, 2019
Hmm...about to hit the Earth, an asteroid, you say.
Well, bend over and kiss goodbye, your hemorrhoids, I say.

May 01, 2019

First to go will be the leadership that failed to plan for it and covered it up with propaganda, lack of warning and fatalism. The mob will hang them, after proper trials of course.

May 01, 2019
@rrwillsj and anonym,

You are both right. Nukes would work but they would have to drill into the putative solid iron or rock asteroid, most likely from several directions and plant several nukes, in order to be sure that some internal non-symmetric structural abnormality didn't just break it a little and move a few chunks out of the way. That would make the below ground analogue. The 1 G is a red herring.

That means getting out there in its way with a satellite that can actually drill instead of just detonate. Of course, that part could be made easier in tandem with conventional explosives if practiced on non-earth-threatening asteroids to get the technique.

If NASA was worth its salt, they would have lobbyists raking in billions from Congress on this threat instead of hustling Congress with global warming studies for a few nickels.

May 01, 2019
Would America ever risk a failed launch explosion with a big nuke on board, if it was Russia in the asteroid's crosshairs? (or Vice versa) .. I think not..
Which is interesting considering how many nuclear tipped ICBM's America was willing to risk blowing up in their silo's on American soil in order to attack Russia.

May 01, 2019

A failed launch explosion? Are you daft? Do you know how many have been lost aboard planes and subs already? They have to be armed first before they can go boom. So, it would be a speck in the Ocean off Cape Canaveral next to Fukushima. My god man, put it in perspective.

Would it be risked? I think yes. Refer to my comment about fatalists and the mob.

May 01, 2019

I missed the part about the Russian crosshairs. Look, even a non global extinction asteroid could make it winter where you are for a long, long time. That means right after you finish chuckling about winning the cold war, you have no food because of snow in summertime everywhere.

I guess a smaller city buster might get played your way for spoiled sport, even if we had the capability.

The point is we need the capability.

May 01, 2019
If a projected asteroid hitting Russia was big enough to trigger an "extinction level event' congress might just sanction a US launch to save the world. (If the NSA gets the denialists locked up)

But otherwise their track record of putting spanners in the works isn't good. Congress had to be kept out of the Manhattan project to stop them screwing it up. Then once it was complete they passed laws preventing the helper nations seeing the research they had created.
Congress interference in the development costs of radar delayed it just enough for Pearl harbour to be a surprise attack.

Given that global warming is a pending limited extinction event which threatens to flood New York you think they would have stopped fighting themselves long enough to look to the future... But No.

Congress aren't suicidal, just invariably stupid and self obsessed.

May 01, 2019
jax. I trademarked
Stepping Stool
Earth/Luna Infrastructure of Orbiting Automated Factories.

Nukes will not explode in vacuum as they do within the Earth's surface atmosphere.

If you can tunnel into a solid or gravelpit asteroid?
You have no need to waste costly weapons.

The mining process can eject the mass specifically needed to steer the rock away from the Earth.
"For every action there is an equal & opposite reaction."

Wouldn't take very much energy to accomplish propulsion.
Just planning ahead & patience.

NASA has PR people to try & explain to the Public what their tax money is paying for.

The lobbyists are Corporate shills offering campaign contributions to the congresscritters.
To get their corporate snouts a share of all those lucrative contracts.

An inefficient system created during imminent threat of atomic war.
Widely dispersing key military-industrial facilities & skilled personnel across the continent.
Same reason academic & research in every state.

May 02, 2019

We agree an ELE like Chicxulub (10,000 meters) would be stopped if we could get our act together and develop the capability.

And, I agree with you for something smaller like the Tunguska (60 meters, 30 megatons) or the Chelyabinsk (17-20 meters, 0.5 megatons) folks outside the path might not attempt to rescue, even with the capability.

However, any asteroid larger than 200 meters (800 megatons) would have more energy than the Tambora eruption of 1815 in Indonesia, an eruption that created a snow covered summer across North America and caused widespread famine, the infamous "year without a summer."

Let's assume that two years of no summer would take four times the energy. Apophis is 370 meters across and at least 3000 megatons. If Apophis were (only) headed for Antarctica, but risked a two year famine from the dust cloud, would you launch? I think the answer is clearly yes.

May 02, 2019

P.S. Global warming is scientific and political gobbledygook. What can accurately be said for it is that it is code for Peak Oil, and that it is a way of determining where that loss will fall, while divorcing that decision making from democracy, as well as international price discovery when the buyers market for oil flips to become a would-be sellers market.

May 02, 2019
The term Global Warming is a simple-minded political slogan that the anti-science denierbots screech to try to suppress scientific evidence.

Global Warming is one part of Global Climate Change.
Which is the correct choice of designations for the planetary phenomena of roasting your butt off at noon.
Then freezing your ass off that midnight.

Without having to move a single meter in any direction.

Unless the floodwaters of the supercaine are shoving you across the barren drought wasteland you bulldozed & burned.

Oh deer, forcing you to face the true issues honestly, has made you cry.


Even better will be the tears you will shed as you pound on the airlock to your carbon master's bunker,
Begging to be admitted.

There the giant cockroach archeologists will find your skeleton curled up on a big pile of your own coprolite.

Placing you on exhibit in their museum as an example of how stupid "Big Brains" could be.

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