Undetected Tunguska-sized Asteroid Narrowly Misses Earth

[Former Dean Phillips Supporters for Haley (I guess???!?) 👁️]

747-sized asteroid skimmed by Earth, and scientists didn't see it coming.

Dubbed 2021 SG, the asteroid flew close to the planet on September 16, but because it came from the direction of the Sun, scientists didn't see it coming.

A large asteroid as wide as the wingspan of a Boeing 747 passed by the Earth recently, and scientists didn't even see it coming.

Dubbed 2021 SG, according to the NASA-backed International Astronomical Union's Minor Planet Center, the asteroid has a diameter of anywhere between 42-94 meters, with an average diameter of 68 meters. This size is around the wingspan of a 747, and is also around the height of the Cinderella Castle in Disney World and around half the size of the Great Pyramid of Giza.

The asteroid flew past the Earth on September 16, as noted by asteroid tracker EarthSky. However, scientists only detected it the next day.

...

This may seem surprising, given how many asteroids are routinely detected by astronomers and space agencies all over the world. However, this asteroid came from a relative blindspot: the direction of the Sun.

Most asteroids detected by agencies like NASA come at Earth from the "front," meaning they come from the direction facing into the interior of the solar system, coming towards the Earth and the Sun.

But there are asteroids that come from the "back," heading towards Earth from the direction of the Sun and heading outwards.

Due to this, it is very difficult to see these objects as they approach Earth, especially as they often tend to approach during the daytime when visibility is low due to the Sun's glare.

Generally, the best time to spot these objects is during twilight. This is the case for all objects in space between the Earth and the Sun, such as the planets Mercury and Venus.

According to EarthSky, the asteroid passed by at a very close distance, around half the distance between the Earth and the Moon. It was closest to the planet at around 4:28 p.m. EST, passing by Greenland and Canada. This is a very close call, as most asteroids that pass by the planet do so much farther away.

And while it may seem like a freak isolated incident, that might not be the case.

On September 7, astronomers in Arizona detected an asteroid, now designated 2021 RS2, coming from the direction of the Sun just hours before it was set to pass by the planet, as noted by EarthSky. Though it was small, around 3.5 meters, it came just 15,340 km. away from the planet's surface.

The Tunguska meteor which hit earth in 1908, and which destroyed 830 square miles of wilderness forest in Siberia, had a diameter of 50–60 meters according to wikipedia. So this was about the same size as that. If an asteroid that size were to hit a populated area, it could easily kill many millions of people. Of course, an even larger asteroid could end civilization, much as an asteroid is thought to have caused the extinction of the dinosaurs.

Now, what does this have to do with politics? Well, asteroid impacts are in principle preventable. But to have any chance to prevent a meteor strike, we have to be able to detect the meteors.

There was a NOVA PBS documentary recently about the threat posed by asteroids to the earth, which discussed plans to send the Sentinel satellite into space. The Sentinel satellite was designed specifically to detect asteroids that we cannot otherwise see, because they come from the direction of the sun and we are blinded by the sunlight. And that is exactly where this particular undetected asteroid that could have hit earth came from:

https://www.pbs.org/wgbh/nova/video/meteor-strike/

DONALD YEOMANS (Jet Propulsion Laboratory, NASA): The most efficient way to discover these near-Earth asteroids would be to have an infrared telescope in space, because these objects are dark and they radiate strongly in the infrared wavelengths.

NARRATOR: Known as Sentinel, the proposed instrument would take up a station in an orbit around the sun. Clear of atmosphere and packed with infrared sensors, it would allow us to detect asteroids far earlier and with greater accuracy.

RUSTY SCHWEICKART: Sentinel will discover something on the order of 50 percent of the city-buster objects, and it will discover close to 100 percent of objects that are about 140 meters in diameter.

NARRATOR: Not perfect, but a vast improvement over the situation we are in today.

RUSTY SCHWEICKART: Right now, to be honest with you, we're driving around the solar system without any insurance.

NARRATOR: Many scientists believe investing in this kind of insurance would be worth it, to scan areas of space invisible from Earth.

MARK BOSLOUGH: In principle, we could have discovered the Chelyabinsk asteroid in advance. If we had a space-based observing system that was surveying the sky for objects that were on collision courses that had the potential to run into the earth, even from the sunward side, we could have issued a warning in Chelyabinsk.

But funding for Sentinel was canceled by the government in 2015, despite it being very inexpensive as compared to other things we waste trillions of dollars on, which leaves us blind to asteroids. We know that it is only a matter of time before another significant asteroid hits the earth.

People are wired to ignore or downplay "natural" threats and only to obsess about threats that are directly from other people - threats that have "intentionality." That is why previously, the threat from pandemics was underestimated. And it is also why we continue to downplay the threat of climate change, while meanwhile we spend enormous amounts of money on the defense budget to defend against other countries (non-"natural" threats). And similarly, we largely ignore the threat posed by meteor impacts. The probability of a devastating meteor impact on any particular day, week, month, or year is low. Most likely it won't happen in our lifetimes. But it could. It is a 100% certainty that sooner or later there will be one - or at least there will be, if we continue to refuse to devote a minimal amount of resources to ensuring that it doesn't happen.

[Former Dean Phillips Supporters for Haley (I guess???!?) 👁️]

And predictably, this thread is ignored. If someone posted a thread about the risk from pandemics and policies that might be able to protect us against pandemics in 2019, I presume it would be ignored also for the same reason. We are averse to planning ahead to deal with problems and serious disasters before they happen, and prefer to instead wait until a disaster happens and it is too late to do anything about it. For the same reason, we will continue building lots of houses in areas that are especially vulnerable to hurricanes etc.

Meanwhile, the Gabby Petito thread has 67 posts.

Perhaps, some time over the next 50 years, a meteor similar to the one that hit Chelyabinsk in 2013 will hit the earth and happen to hit a population area, killing a million people. If so, maybe some future historian will later write a book about how this was allowed to happen, and look back through old internet records to try to figure out why people didn't do something in the past. Maybe the future historian will see this thread. If so, hi future historian! (waves)!

My message to you, future historian, is that the problem here is human nature. This is the sort of threat that we are inclined to ignore, because it is easy to ignore. If you want to do something to prevent similar sorts of events in the future, you will need to set up some sort of special program designed to overcome this problem with human nature. You need some sort of program that is specifically mandated to look for disasters that could create a great amount of damage if they happen, but which are unlikely to happen at any particular time, and where no human being is directly personally responsible for committing an act that causes the disaster (i.e. not terrorism or an act of war). And then have the program be mandated and funded to prepare for and prevent those sorts of disasters.

[Yeahsayyeah]

Earth could be hit by a gamma ray, tomorrow. You can't plan for all risks. A Tunguska-sized meteor hitting a big city would be devastating for that city, but not for the world as a whole.

[Adam Griffin]

There was a NOVA PBS documentary recently about the threat posed by asteroids to the earth, which discussed plans to send the Sentinel satellite into space. The Sentinel satellite was designed specifically to detect asteroids that we cannot otherwise see, because they come from the direction of the sun and we are blinded by the sunlight. And that is exactly where this particular undetected asteroid that could have hit earth came from:

But funding for Sentinel was canceled by the government in 2015, despite it being very inexpensive as compared to other things we waste trillions of dollars on, which leaves us blind to asteroids. We know that it is only a matter of time before another significant asteroid hits the earth.

Not to be pedantic, but...for what it's worth and at least in this particular case, the satellite wouldn't have been able to detect it because both the original version - as well as its identical planned reboot, the NEO Surveyor (due to deploy in 2026) - are only designed to track asteroids with a mean diameter of ~150m.

[Former Dean Phillips Supporters for Haley (I guess???!?) 👁️]

Earth could be hit by a gamma ray, tomorrow. You can't plan for all risks. A Tunguska-sized meteor hitting a big city would be devastating for that city, but not for the world as a whole.

It is true that we can't defend against gamma ray bursts, at least not now (maybe it might be possible with some future technology we can't even imagine, but probably not in the foreseeable future).

But scientists have said that in principle they think we could defend against a major asteroid impact with basically current technology, as long as it were detected and predicted well in advance. We could send a space mission to the asteroid and hit the asteroid with some sort of kinetic force to redirect its trajectory away from the earth. If we hit the asteroid with the kinetic force at a far enough distance from the earth, only a very small change in its trajectory would be needed for it to end up missing the earth.

The fact that we can't defend against gamma ray bursts is not a reason to not defend against asteroid impacts, if asteroid impacts could cause large scale damage and are preventable.

[Former Dean Phillips Supporters for Haley (I guess???!?) 👁️]

Not to be pedantic, but...for what it's worth and at least in this particular case, the satellite wouldn't have been able to detect it because both the original version - as well as its identical planned reboot, the NEO Surveyor (due to deploy in 2026) - are only designed to track asteroids with a mean diameter of ~150m.

It is good that the NEO surveyor is planned, but will it actually end up happening, or will its funding get cut and canceled like Sentinel?

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

In 2005, the U.S. Congress mandated NASA to achieve by the year 2020 specific levels of search completeness for discovering, cataloging, and characterizing dangerous asteroids larger than 140 m (460 ft) (Act of 2005, H.R. 1022; 109th),[11][3] but it never appropriated specific funds for this effort.[12] NASA did not prioritize this mandate, and directed the NEOCam project to compete for funds against science missions unrelated to planetary defense or disaster mitigation planning.[13][14]

It is an easy thing to de-prioritize, because a large impact is unlikely to occur at any particular time, and no individual politician or bureaucrat is likely to suffer from being particularly blamed even if it does. I can see a future Congress or Administration de-prioritizing/de-funding this also.

Unless we recognize now that the risk is real (though small) and the cost is low, so it is worth doing.

[ProudModerate2]

Thank you for posting this.
Interesting story.

[emailking]

But scientists have said that in principle they think we could defend against a major asteroid impact with basically current technology, as long as it were detected and predicted well in advance. We could send a space mission to the asteroid and hit the asteroid with some sort of kinetic force to redirect its trajectory away from the earth. If we hit the asteroid with the kinetic force at a far enough distance from the earth, only a very small change in its trajectory would be needed for it to end up missing the earth.

In principle it is possible, but realistically we probably wouldn't be able to do anything at all. Here's a good video on it.

https://www.youtube.com/watch?v=4Wrc4fHSCpw

[Xing]

Thanks for posting this. And, of course, you're right about the lack of comments here. It's unfortunate, people always seem to gravitate toward discussions in which there's a clear and tangible enemy, or at least someone that they can blame/get mad at. Threats such as asteroids are more unsettling, since there are no "sides", no labels we can identify with (though I worry that how to deal with a potential asteroid impact would become a "divisive, partisan issue" if it were to actually happen.) In fiction, it seems like this is a common theme; different groups of people bickering and as a result ignoring a potential existential threat since they can't get along until it's too late.

Even if deflecting an asteroid in the "blind spot" (and detecting it in time) would be extremely difficult with our current technology, that does not mean that we should not prepare for the possibility and fund projects such as the NEO Surveyor.

[emailking]

This shows the scale of the Earth to the moon. (You have to be logged in to see image.)



Now cosmically coming half way between is close, sure. But the vast majority that pass at a distance between the Earth and the moon are going to miss.

[Kahane's Grave Is A Gender-Neutral Bathroom]

This reminds me of my third grade science project to build a system of satellites with lasers to push all asteroids out of harm's way and onto Chinese cities.

[Continential]

This reminds me of my third grade science project to build a system of satellites with lasers to push all asteroids out of harm's way and onto Chinese cities.

So do Chinese civilian lives not matter?

[Kahane's Grave Is A Gender-Neutral Bathroom]

This reminds me of my third grade science project to build a system of satellites with lasers to push all asteroids out of harm's way and onto Chinese cities.

So do Chinese civilian lives not matter?

This was when I was in third grade. My opinions have since changed.

We should now target them at China and Russia.

[Continential]

This reminds me of my third grade science project to build a system of satellites with lasers to push all asteroids out of harm's way and onto Chinese cities.

So do Chinese civilian lives not matter?

This was when I was in third grade. My opinions have since changed.

We should now target them at China and Russia.

I guess Russian civilians should die as well.

[Kahane's Grave Is A Gender-Neutral Bathroom]

This reminds me of my third grade science project to build a system of satellites with lasers to push all asteroids out of harm's way and onto Chinese cities.

So do Chinese civilian lives not matter?

This was when I was in third grade. My opinions have since changed.

We should now target them at China and Russia.

I guess Russian civilians should die as well.

joke
/jōk/

noun
a thing that someone says to cause amusement or laughter, especially a story with a funny punchline.

[Houstonian Sock]

Was it really undetected or did they see it and say nothing?

[emailking]

Was it really undetected or did they see it and say nothing?

It was undetected until after it passed Earth. It can't be detected from that angle of approach. If they somehow knew about it, they would have known it would not strike Earth so no reason not to say something.

[○∙◄☻¥tπ[╪AV┼cVê└]

The cancelled telescope was much cheaper than Iron Dome, whose proponents say is chump change.

[Houstonian Sock]

Was it really undetected or did they see it and say nothing?

It was undetected until after it passed Earth. It can't be detected from that angle of approach. If they somehow knew about it, they would have known it would not strike Earth so no reason not to say something.

How do we know that it could not be detected

[emailking]

It's explained in the OP.

[ProudModerate2]

[Calthrina950]

I recall having seen a story about an asteroid that was similar, or perhaps even larger, than this one, that passed by the Earth several years ago. Reading about this story reminds me of the movie Deep Impact, which was released more than twenty years ago and is about an asteroid threatening the Earth. Such an event is certainly a terrifying prospect, and one that we're not prepared for. But as has been said elsewhere, there are other dangers out there. We could have a more deadly virus than coronavirus, a gamma ray, a supernova, or a devastating alien invasion at any time. Life is full of risks.