NASA predicts asteroid to make one of closest approaches to Earth ever recorded | Hacker News Reader

NASA predicts asteroid to make one of closest approaches to Earth ever recorded

jpl.nasa.gov

The article includes an inline embedded version of Eyes on Asteroids (https://eyes.nasa.gov/apps/asteroids/#/asteroids), which is an amazingly impressive interactive live visualization of asteroids in the solar system. Dragging the time slider at the bottom lets you wind time backward and forward and watch the power-law relationship between orbital speed and radius (v ~ 1/sqrt(r)) in glorious fluid animation of countless asteroids swirling in the prevailing orbital direction of the solar system almost as a fluid. A masterful combination of data, graphics, software engineering, and UX.

It's worth taking a tour by clicking on particular objects that will zoom in close and show each object as seen by space probes that have visited. E.g. 21Lutetia that was photographed by Rosetta in 2010 is a 90km diameter oblong rotating once every 8 hours with three separate sets of impact craters in tight groups showing the impacts in each group were likely fragments of single objects. The craters are about 10-20km across.

Eros in June 2028 looks pretty close to earth.

The one in the article is gonna be <5,000km away. Eros is always like at least 15,000,000km+ away, at its closest. Something like that.

True- Eros is much larger though. I was just interested in using the technology on the website - not trying to be alarmist or anything :)

Notice that this was spotted by an amateur only 2 weeks before closest approach. Why was it not found by the larger installations?

One problem I like to repeat at times like this, is that these hunts for near earth asteroids look for bright spots that move against the background stars. That's a nice way to find things nearby. But any object on a collision course with earth will not be moving against the background in the days and weeks leading up to the collision when they are also the brightest and most observable. I believe this is why the ones that have exploded in the atmosphere in recent years went completely undetected. It's not just that they're small, but that they don't have the relative motion against the sky to make them stand out.

Congress mandated that NASA construct a surveillance capability for relatively-large NEOs (larger than the ones in OP), so the detection problem has been well-studied. A little googling will turn them up, but here's what I remember:

- Detection in optical by ground-based telescopes is a good technique. You need several exposures and good spot-tracking. Because of the relatively short time-base, you also need good follow-up or else the NEO diverges from your estimated orbit and is lost again!

- The parallax issue you mention comes up more regarding orbit determination than detection per se. (I.e., you need more than just detection to do anything useful.) One link going deep on the relationship of parallax to good orbits: [1]

- There are a bunch of such optical surveys, e.g. Pan-STARRs [3].

- But ground-based telescopes rely on reflected light, and so NEOs coming from certain regions (e.g., within Earth's orbit, but it's worse than that) don't have much reflected sunlight so are hard to detect optically.

- So, IR telescopes can be used, but you have to go above the atmosphere. See, NEOSurveyor [2]. IR is based on the infrared "glow" of a NEO against the background, and so it does not rely on reflected light. So IR telescopes get around many of the geometric limitations of optical.

- What about radar? It's very useful for follow-up orbit determination, but not so good for surveys, because the radar energy diffuses so much. Crudely, if the NEO is R away, you get a 1/R^2 on the way out, and a 1/R^2 on the way back. It's more complicated than that, but this is the reason that radar has limitations for this problem.

[1] https://iopscience.iop.org/article/10.1088/1538-3873/ac43ca/...

[2] https://www.jpl.nasa.gov/missions/near-earth-object-surveyor

[3] http://legacy.ifa.hawaii.edu/research/Pan-STARRS.shtml

None of those links addresses the problem. Finding NEOs is important because they pass by repeatedly and can be tracked. My point is that one on a collision course is not detectable with that method of looking for motion against the background.

The second point highlighted by a "-" is trying to get at that. It's not so much a pure detection issue, it's a tracking issue.

My understanding is that the robotic scanning telescopes can detect these objects, but that unless they get a high-quality track, the telescope has already moved on with its scan and the NEO will be lost. That is, detection is hard, but tracking is harder, and you need tracking.

And I guess my comments are also directed at the "systems" aspect of the NEO protection problem - detection, tracking, followup.

> Dan : [the President asks about the size of the asteroid] it’s the size of Texas, Mr President.

> President : Dan, we didn't see this thing coming?

> Dan : Well, our object collison budget's a million dollars, that allows us to track about 3% of the sky, and beg'n your pardon sir, but it's a big-ass sky.

But with computers and sky tracking charts shouldn't it be trivial to find new spots in the sky without using parallax? Anything new should be pretty note worthy.

Not all asteroids are “bright” enough to be imaged from earth, the problem is the low albedo asteroids you cant see, thats why we need this: https://solarsystem.nasa.gov/missions/neo-surveyor/in-depth/

And even that won't see one on a collision course because there is NO Motion to detect when an object is on collision course.

Right. If you can't see them, you can't see them. It's not a parallax problem.

how far away would you need them to be to detect/be able to respond

you could put LIGO-type "stationary" satellites around Earth to detect heavy things moving

in boxed grids then estimate trajectory over the affected cubes

Is there no parallax as the Earth moves around the Sun? Are these asteroids in some crazy hyperbolic orbit coming in straight from outside the solar system?

No, it looks like this asteroid had a similar trajectory as Earth around the sun, but after the encounter its path will be altered significantly.

"Before encountering Earth, the asteroid’s orbit around the Sun was roughly circular, approximating Earth’s orbit, taking 359 days to complete its orbit about the Sun. After its encounter, the asteroid’s orbit will be more elongated, moving it out to about halfway between Earth’s and Mars’ orbits at its farthest point from the Sun. The asteroid will then complete one orbit every 425 days."

How sure are they that this isn't just some spent rocket from 40 years ago?

Shameless plug: if you're interested in daily space information, including about nearby passing asteroids, give my Alexa skill "Spaceman" a try.

It provides info about those asteroids, as well as any scheduled rocket launches, for any date or date range. And it throws in the moon phase as well.

https://sites.google.com/view/spacemanforalexa/

I should probably add that my app isn't reporting this event. For some reason, my upstream data source[1] isn't reporting it to me. I guess it's such a new discovery that they haven't got it into their database yet.

[1] NeoWs at https://api.nasa.gov/index.html

> The asteroid was discovered by amateur astronomer Gennadiy Borisov, discoverer of the interstellar comet 2I/Borisov, from his MARGO observatory in Nauchnyi, Crimea, on Saturday, Jan. 21.

Discovered 5 days before its closest approach.

It’s amazing how much “stuff” is out there to learn, and how something can sneak in so “close”.

Imagine standing in a field on a moonless night while someone shines a flashlight at you from one direction. You are told you are surrounded by a number of people whom you can't see and that they will now proceed to throw rocks at you ranging in size from pebbles to bricks. That's roughly the level of anxiety you should have about our current situation.

Oh for sure. No anxiety at all. Just so NEAT that there is so much out there.

Wouldn't they be throwing the rocks at the flashlight guy?

Well, to make the analogy work you'd be running circles around flashlight guy while they throw at him. Maybe you're in the crossfire, maybe not.

But the other part that I think the original OP is sort of amazed at is that we're unable to detect these through some sort of automated system more accurately. It isn't fair to compare our space/vision capabilities to the eyesight of a person alone. Do we not have satellites or installations doing ""short range"" scanning with radio/laser/something-else-I-am-not-an-astronomer-don't-hate-me ? How come it was an amateur picking this up so close to the specific date?

>canning with radio/laser/something-else

R-squared is not your friend. This would take a massive amount of energy.

You'll be horrified when you Google just how much of the sky we're able to observe at any one point using everything we've got online right now.

I (op) was just amazed at how much is out there, how this shows what we have yet to even know, let alone “look out for” etc. Was a comment on scale nothing else.

No, they're stand-ins for the trajectory on closest approach to Earth. They're not trying to get the rocks to orbit flashlight guy.

Flashlight guy is the sun blinding you so you can't see anything.

Sometimes they are only discovered after the closest approach. It depends a lot on where they're coming from relative to the sun.

Damn. I almost wish I didn't know this.

When I was about 10 years old 1983 (+/- 2 years) I was 'camping' in my backyard with a friend. While we were running around in the dark we saw an asteroid bounce off the atmosphere and either enter below my visual horizon or pass by the earth.

It was about the size golfball/chicken egg held at arms length. I was facing East-South-East (approximately).

It was a bright red, and I could see impact craters on the surface of it. There were no 'flames/fireballs' from orbital entry friction.

The entire incident lasted less then 10 seconds (but this is very much a guess, and impacted by the time-frames involved).

A golf ball is around 4cm, and an arm's length is around 70cm. To be the same apparent size, it would have to maintain that same ratio. The atmosphere is like 50-100km thick (highest weather balloon flight was >50km) so you would have to be seeing it at a further distance than that.

So your asteroid would have to be at least several kilometers across. That approaching dino-killer size. You're definitely misremembering some part of this.

It's not impossible. How closely were we tracking 3 km objects in 1983?

The US and USSR were looking very closely for much smaller objects leaving and entering the atmosphere.

True, but are they finding them - especially the ones on the sun side of our orbit? Remember, this one was found by an amateur. Now, NASA is claiming authority for it.

There's no way you saw any impact craters on an asteroid naked eye. You have a false memory

Rare instance where this story would be more believable if you'd said it was a alien space ship.

I think it's unfortunate that our government (in the US) is spending trillions left and right, but won't spend a few Billion to address genuine existential threats such as early detection of asteroids.

Someone should tell them that Ukraine would be impacted too.

>There is no risk of the asteroid impacting Earth. But even if it did, this small asteroid – estimated to be 11.5 to 28 feet (3.5 to 8.5 meters) across – would turn into a fireball and largely disintegrate harmlessly in the atmosphere, with some of the bigger debris potentially falling as small meteorites.

Well, the article clearly states that the asteroid is of no risk on impacting Earth and even if the asteroid entered our atmosphere it would most likely disintegrate into bits and pieces, considering the size estimated to be 11.5 to 28 feet (3.5 to 8.5 meters) across; I would say it's harmless..

0.00007 AU is how close the approach is estimated to be which is ~6500 miles. So I think we're safe haha.

It's also tiny, less than 10m across. Barely enough to reach the ground before disintegrating due to atmospheric heating.

For comparison, the Chelyabinsk meteor was about 20m in diameter. The Tunguska event was 50-60m.

"2023BU: Earth is about to get one of its closest ever asteroid encounters (bbc.co.uk)" - https://news.ycombinator.com/item?id=34530744

I wish they publicised error bars on these approach distances.

What's the equation to calculate if such object given its mass, velocity, etc would get pulled into Earth orbit or collision or just fly past?

The equation is: if it isn't already in orbit, and it doesn't hit the atmosphere, then it flies past.

For an incoming object to start orbiting earth, it has to decelerate through active propulsion or aerobraking or something like that.

Sounds like a nice heuristic but I don’t think that covers every case—and it’s not an equation. Sorry, wrong answer!!

It does cover every case though. The solution for the orbit of a mass in a 2-body problem is always an ellipse! (Or a parabola/hyperbola for an escape trajectory). You can find the derivation here [1], it's not too complicated.

There is no way for an asteroid and the earth to interact gravitationally to change the asteroid's orbit from what it was coming in. Non-gravitational interactions (like hitting the earth/atmosphere) can do it.

Also, over many interactions and a long time you can have orbital capture in many-body situations, but there is no general equation for this (look up 3 body problem). This is how you get objects accumulating at Lagrange points for example.

TLDR: The equation you're asking for does not exist. Sorry, wrong question!!

https://en.m.wikipedia.org/wiki/Orbit

Wow so some random Russian amateur found this and was just like hey that looks like it's coming for us?

It's like that Elisa Wood movie. At least the message got through

Pretty sure closer approaches have been recorded. They just don't escape afterward.

Don’t look up!

This is HN, I can be cynical, right? Allow me to air one of my pet peeves: articles that make the threat of an asteroid collision with Earth something we should be afraid of. (Oh, and films of course.)

I never understood why anyone should give it any more than even a passing thought. As a layman my understanding is that the last great extinction event from an asteroid was like (Wikipedia tells me) 66 million years ago.

With that frequency/odds my fears seem much better afforded toward the dangers of climate change or any number of other issues that likely will have repercussions in my or my grandchildren's lifetimes.

In between the extinction-level asteroids and the mostly harmless ones is a medium-size class of asteroids about the size of a football pitch. Those are the scary ones. They are small enough to be hard to spot, and there are enough of them that one of them hits earth every 10,000 years or so. They have not been a big deal in the past. They don't cause mass extinctions, but they are more than big enough to bring about the end of civilization. If one of them hits an ocean (which is the most likely scenario) it will cause global tsunamis that will make the Fukushima event look like a small ripple. We're talking waves many hundreds of meters high. Not a single coastal city bordering the ocean where the asteroid hits would survive.

This is an excellent way to do what-if scenarios https://neal.fun/asteroid-launcher/

Meh, I dropped one like GP mentioned in the north atlantic and other than mentioning the size of the Tsunami, all of the other factors assumed it was dropped within miles of land.

We don't know when the next big one is coming, because we don't have perfect knowledge of all objects in (or travelling through) our solar system.

On the scale of things to be concerned about, I'd agree that Climate Change is definitely something that we should be proportionally spending more resource on.

We have the capability of solving multiple problems at once, though - it's not an all-or-nothing thing. So I think running observation/detection systems is worth it, even with the occasional news release about significant close-approaches.

> We have the capability of solving multiple problems at once, though - it's not an all-or-nothing thing. So I think running observation/detection systems is worth it, even with the occasional news release about significant close-approaches.

Well said, I agree. This applies to a lot of things that people often ask, “but shouldn’t we focus on X instead?” about.

We have both the people and the resources to do multiple things at once, and we should, if only because it doesn’t help anybody to tell people who’ve spent a large chunk of their lives working on asteroid defense, rockets, crewed spaceflight, etc that their job is gone and they have to start over from scratch and work on X instead.

The great extinction events are just icing on the cake. We get hit by rocks quite often, one of the most recent notable ones being the one that caused the Burckle Crater in the Indian ocean. The crater is 29km in diameter and the impact happened roughly 5000 years ago. The ocean impact would have created a mega-tsunami that devastated the coastlines of Australia, India, Africa, and South Asia. God knows what the fallout from it would have looked like but it would have vaporized a lot of water and also flung masses of ejecta into the atmosphere. Land impacts can be a lot worse since the damage isn't just limited to the impact site, that ejecta again creates a large radius of splash damage. Then there are the fires, the smoke, a nice dusting of radioactive material, and don't forget the shockwave and overpressure.

We've been lucky so far but you'd have to be a fool to rely on luck forever.

> This is HN, I can be cynical, right?

Your comment isn't cynical, it is more akin to a lucid perspective of a set of threats.

The economy and threats to democratic process are more worrisome -- and yet at the same time, much more within our capability to fix than an asteroid strike.

For a lucid fictional presentation of an asteroid strike, I recommend "Lucifer's Hammer" by Niven and Pournelle.^1

[1] https://en.wikipedia.org/wiki/Lucifer%27s_Hammer

Yeah super volcanos and solar flares on the other hand... <I don't know how likely those are either, but they seem superscary isn't yellowstone overdue?>

For what it's worth, Yellowstone's upper lava chamber is 5% molten and the lower magma chamber is about 2% molten. To get eruptions that percentage has to be much higher as it is in the Hawaiian volcanoes. Scientists have differing opinions on how many years it will take to reach that level but all of their numbers are well over 10k years. I had to look into this prior to moving near it.

Still, I fear for my offspring... a man has no path to immortality, save for his precious seed from his loins, and women their ovaries.

What if an asteroid hits it?

Good timing on the question. We are about to pass through a chunkier part of the Taurid asteroid belt. If the rock is big enough to turn everything molten then I suppose it might be time to hitch a ride in a nuclear submarine.

Yes, a super massive strike is likely very rare and does not happen very often. But smaller asteroids hit the planet more frequently (relatively speaking), yet would still cause a huge catastrophe. It wouldn't cause a mass extinction, but it would still... suck.

The fact that it happened so long ago makes it more likely to happen sooner. Also, my understanding is that we don't really have a good grasp of what's out there outside of of the immediate vicinity of Earth. There are millions and millions of them hurling through our system. A planet-killer can show up on our radar any day.

Wait, isn't that the Gambler's Fallacy?

Gamblers fallacy is about independent probably - there are cyclical natural catastrophes.

> there are cyclical natural catastrophes

That sounds very made up.

I don’t really follow astrophysics, but there were hypotheses that the motion of the solar system through the galactic plane, which has a periodicity, would induce impact events. A cursory search suggests that recent analyses of crater data may not support those hypotheses. Here’s a link to a 2011 paper suggesting as much.

So the notion was certainly a reasonable one even if not ultimately true.

https://academic.oup.com/mnras/article/416/2/1163/1058876

It's way beyond a three body problem though, so it's chaotic even if it's recurrent... even trying to retrodict precise correlations in celestial events 10k years ago is difficult, doing this would be way harder. The only thing I can think of on that scale that's somewhat predictable within meaningful margins is Milankovich cycles. Cool paper though. Thanks for sharing.

(And to note: I can't edit my reply now but I read 'there' as 'these'. Obviously there are other (somewhat) cyclic natural catastrophes especially on shorter timescales.)

Sounds a little like Nemesis [1].

The Wikipedia article mentions 26 million year intervals. So we're probably good for another 10 million?

[1] https://en.wikipedia.org/wiki/Nemesis_(hypothetical_star)

The nature of orbits makes the "cyclical" aspect seem reasonable to me. Especially in light of how many objects there are that have extremely elliptical orbits which dip into the inner solar system and out to the Kuiper belt. Or, objects that end up in a resonance that seems stable enough but are modeled to eventually be perturbed into a new orbit.

Well, we know for a fact that every once in a while, we get hit by an asteroid (which is exactly what this is about). I'd call that cyclical and not made up.

Everyone once in a while the roulette ball lands on green and I get a big payout. That's not a cyclical event.

Only because you don't have the money or time to keep playing. But continue playing for 1 million years, and the black and red will hit a similar number of times and the green a proportionally lower number of times.

Hurricanes are cyclical. It’s not made up. I’m sure there’s a season for tornadoes and blizzards as well.

We have a good idea of how many planet-killer asteroids are out there and that we have detected 90% of them. And 100% of the extinction-level asteroids. Planet-killer asteroids are large, kilometers in diameter, and visible. This asteroid is 10m in diameter, way harder to detect which is why didn't detect it until last minute.

The current goal of NASA asteroid detection is 90% of 150m asteroids which can cause regional disaster.

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