Everyone knows it was a large asteroid striking Earth that led to the demise of the dinosaurs. But how many near misses were there? Modern humans have been around for about 225,000 years, so we must have come close to death by asteroid more than once in our time. We would have had no clue.
Of course, it’s the actual strikes that are cause for concern, not near misses. Efforts to predict asteroid strikes, and to catalogue asteroids that come close to Earth, have reached new levels. NASA’s newest tool in the fight against asteroids is called Scout. Scout is designed to detect asteroids approaching Earth, and it just passed an important test. Scout was able to give us 5 days notice of an approaching asteroid.
Here’s how Scout works. A telescope in Hawaii, the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) detected the asteroid, called 2016 UR36, and then alerted other ‘scopes. Three other telescopes confirmed 2016 UR36 and were able to narrow down its trajectory. They also learned its size, about 5 to 25 meters across.
After several hours, we knew that UR 36 would come close to us, but was not a threat to impact Earth. UR 36 would pass Earth at a distance of about 498,000 km. That’s about 1.3 times further away than the Moon.
The key part of this is that we had 5 days notice. And five days notice is a lot more than the few hours that we usually have. The approach of 2016 UR36 was the first test for the Scout system, and it passed the test.
Asteroids that come close to Earth are called Near Earth Objects (NEOs) and finding them and tracking them has become a growing concern for NASA. In fact NASA has about 15,000 NEOs catalogued, and they’re still finding about 5 more every night.
Not only does NASA have the Scout system, whose primary role is to speed up the confirmation process for approaching asteroids, but they also have the Sentry program. Sentry’s role is a little different.
Sentry’s job is to focus on asteroids that are large enough to wipe out a city and cause widespread destruction. That means NEOs that are larger than about 140 metres. Sentry has over 600 large NEOs catalogued, and astronomers think there are a lot more of them out there.
NASA also has the Planetary Defense Coordination Office (PDCO), which has got to be the greatest name for an office ever. (Can you imagine having that on your business card?) Anyway, the PDCO has the over-arching role of preparing for asteroid impacts. The Office is there to make emergency plans to deal with the impact aftermath.
5 days notice for a small asteroid striking Earth is a huge step for preparedness. Resources can be mobilized, critical infrastructure can be protected, maybe things like atomic power plants can be shut down if necessary. And, of course, people can be evacuated.
We haven’t always had any notice for approaching asteroids. Look at the Chelyabinsk meteor from 2013. It was a 10,000 ton meteor that exploded over the Chelyabinsk Oblast, injuring 1500 people and damaging an estimated 3,000 building in 6 cities. If it had been a little bigger, and reached the surface of the Earth, the damage would have been widespread. 5 days notice would likely have saved a lot of lives.
Smaller asteroids may be too small to detect when they’re very far away. But larger ones can be detected when they’re still 10, 20, even 30 years away. That’s enough time to figure out how to stop them. And if you can reach them when they’re that far away, you only need to nudge them a little to deflect them away from Earth, and maybe to the Sun to be destroyed.
Large asteroids with the potential to cause widespread destruction are the attention-getters. Hollywood loves them. But it may be more likely that we face numerous impacts from smaller asteroids, and that they could cause more damage overall. Scout’s ability to detect these smaller asteroids, and give us several days notice of their approach, could be a life-saver.
Two questions, if I may:
1) Dave Dickinson wrote in his latest UT article(*), “Newly discovered asteroid 2016 VA snuck up on us last night, and crossed through the Earth’s shadow to boot. Discovered just yesterday by the Mount Lemmon Sky Survey based outside of Tucson Arizona, 2016 VA passed just 58,600 miles (93,700 kilometers) from the surface of the Earth this morning at 00:42 Universal Time (UT).” Per this same article, the object was 16 m – 19 m across, seemingly large enough to catch with the Scout system.
My first question: why did we have only hours of warning if SCOUT can give us “days?” Was it offline for some reason?
(*)http://www.universetoday.com/131743/watch-asteroid-2016-va-pass-earths-shadow/
2) How many people died due to the effects of the Chelyabinsk meteor? (Initial reports suggested perhaps as many as two, but now I can’t find records of ANY fatalities.) My second question: if no one died, how would 5 days’ warning have “saved a lot of lives?”
As an aside, to say “If Chelyabinsk had been bigger, it would have been worse” adds nothing to the discussion, really. A larger asteroid is correspondingly easier to spot, as the fly-by of 367943 Duende (~30 m wide) on the same day of the Chelyabinsk event demonstrates: we knew Duende was coming & previously had predicted its path; it took Chelyabinsk (~20 m) entering the atmosphere & exploding for us to even know it existed.
I’m glad these systems are being worked on, but it still looks from here like they’ve got a long way yet to go.
1) nothing is perfect, and yes, we have a VERY long way to go, from ongoing improvements in detection accuracy and precision, to the complete lack of any tested deflection methods.
2) it is confusing. However, it is also fairly obvious that the author probably needed another sentence in there to complete the hypothetical example of the meteor being bigger than it was. The author meant that, had it been just a bit bigger (but still below the old detection threshold), then it would have most likely meant loss of life. Then, it follows that a 5-day warning would have saved lives.
“Everyone knows it was a large asteroid striking Earth that led to the demise of the dinosaurs.” You obviously did not do your homework or you haven’t received the memo. An asteroid did not kill off the dinosaurs.
Yes, it did. At least, it was the final blow. The geologic record is perfectly clear on that.
What is likely is that the impact also triggered/enhanced the monumental eruptions of the Deccan Flats, which date to approx. the same time, according to the geologic record, and were diametrically opposite to the asteroid impact site at that time (India was still separate from the rest of Asia, in what we now call the Indian Ocean). That would have provided the other blow of a truly catastrophic one-two punch that caused the mass extinction as demonstrated by the geologic record.
The fact that the fossil record shows that at least some dinosaurs in some regions were already dying off does not change the fact that the asteroid impact made sure of it, all at once.
We were hit 12,786 +- 50 yrs. ago, in the 3200 BC Event, and ~1250BC. Many of the ancient legends tell of four ages of Man. The powers that be assure us that these impacts only happen in the range of hundreds of thousands to millions of years and yet neglect to mention the Barringer Crater at 40-50 thousand years ago. The mythology of mankind is riddled with testimony of Fire from the Sky and The Deluge and yet Man is just beginning to take it seriously. https://sites.google.com/site/fromthedeepoceanabove/
It is unfortunate that oral histories have been largely ignored in the physical-science communities, at least until very recently, and even now, they are recognized by a relatively few research groups. If you can’t stick it under a microscope and quantify it, then it doesn’t exist.
My favorite example is that the indigenous peoples of west-coast North America have an oral history of the Earth rising and falling, and a wall of water wiping out life and limb, in what is now the Cascadia region. It was a tale that dated back to a generation that lived around the turn of the 18th century.
A geologist in the early 1970s was surveying some coastal locations for a proposed nuclear power plant. He discovered some anomalous layers along the sides of a creek in a salt marsh that suggested that the land was much higher and forested roughly 300 yrs ago. It was likely that it was a cataclysmic geologic event, but they didn’t know about the Cascadia fault line at the time (1970s) and went looking for a possible cause.
Not long after the initial investigation, either the same or a different geologist discovered that written records from Japan had what the observers at the time called an “orphan” tsunami in July (or June, I forget which) of the western calendar in the year 1701. The Japanese at the time knew that a tsunami followed every major earthquake, but their records showed an tsunami for which there was no preceding earthquake.
So, the geologists back in the US put 1+1+1 together and got “3”. The Cascadia subduction zone let loose all at once, on approx. July 1st, 1701, lowering the level of the nearby coastline, the tsunami flooding the area and then the area became a salt marsh due to the lower elevation of the land relative to the ocean.
The dates might not be exactly correct, but you can look up comprehensive articles online that go through the whole story. It’s actually very interesting reading, watching the pieces come together from three disparate sources over about 20 years. Needless to say, the nuclear plant was never built.
I read an article about that, IIRC it was back when Fukushima happened and went on to the tsunami stone markers up on the hill sides, strange how mankind forgets. I have read a lot of legends, for example you mention the NW USA, they have one where the Sun goes missing for years as do many global stories. Academia seem to push the diurnal and seasonal aspect as if we were knuckle draggers and that is not what the collective legends tell at all. Just like ‘they’ told us that the nuclear plant was contained after seeing the concrete ceiling sail up hundreds of feet into the air. Also ‘they’, say space falls only happen on 100kyr scale time lines when Barringer Crater is -40-50kys old and we have the -13kyr, the 3200BC, and the 1250BC events…
It only takes one of these small but scary asteroids to hit us, somewhere remote very likely, and the funding for a large asteroid defense will suddenly materialize.