I work on the Near Earth Object Surveyor space telescope (NEO Surveyor) writing simulation code which predicts which objects we will see.
This one has drummed up a bit of interest due to its (relatively) high chance of impact. I actually spent quite a bit of time yesterday digging through archive images trying trying to see if it was spotted on some previous times it came by the Earth (no luck unfortunately). Since we saw it so briefly, our knowledge of its orbit is not that great, and running the clock back to 2016 for example ended up with a large chunk of sky where it could have been, and it is quite small. We will almost certainly see it again with NEO Surveyor years before its 2032 close encounter. I have not run a simulation for it, but I would not be surprised if LSST (a large ground telescope survey which is currently coming online) to catch it around the same time NEO Surveyor does.
Our knowledge of the diameter of this object is a bit fuzzy, because of surface reflectivity, small shiny things can appear as bright as dark large things. This is one of the motivations of making the NEO Surveyor an IR telescope, since IR we see black body emission off of the objects, which is mostly size dependent, and only weakly albedo dependent.
There is an even tinier chance that if it misses the Earth in 2032, it could hit the moon. I haven't run the numbers precisely for that one, but it impacted a few times in some monte-carlo simulations.
If anyone is interested in orbit dynamics, I have open sourced some of the engine we are using for observation predictions: https://github.com/Caltech-IPAC/kete
It is relatively high precision, though JPL Horizons has more accurate gravitational models and is far better suited for impact studies. My code is primarily for predicting when objects will be seen in telescopes.
Where does the uncertainty (1%) come from? For example, is it more from our ability to precisely determine the orbit based on limited observations, or is it because orbits for objects like this just aren't predictable years out, or something else?
It's a bit of both, observing has uncertainty in a lot of places, if you are on the ground you get atmospheric effects, imprecision of timing, imprecision of optics, etc etc. You are also observing an object where you dont know how far away it is. That distance has to be solved by basically doing a sort of triangulation, which requires either the observer or the object to move enough.
So if you observe over a short time (hours for example), you can see it is moving, but it is hard to tell distance.
Once you have an estimated orbit, if it has any interactions with planets (IE: flyby of Earth), small differences in positions during the close encounter make LARGE differences decades later. Add to this the effects of photons from the sun pushing on the smaller asteroids or dust, or out-gassing /dust from comets cause these objects to slightly drift from just the basic gravitational forces. Generally inner solar system asteroids (inside mars) are very chaotic over hundreds of years, though typically predictable less than a century.
Note that I am not an expert on impact calculations, I just know a bit about and and can do back of the envelope ones.
There are a number of ways to get to the ~1%, the orbit fits have uncertainties on them and those can be propagated forward in time. However there are all sorts of complexities with doing that, and often the easiest method is to sample the uncertainty region a few hundred thousand times (Monte-carlo), and propagate those and see what hits.
Parent mentioned Monte Carlo simulations, which allow you to simulate across a range possible scenario parameters and see what % result in some outcome (like a collision with Earth or the moon).
My guess is that small objects like this suffer greatly from the 3-body problem, and multiple trajectories are generated from various starting points inside our measured error bars for the current states of these objects. Small inaccuracies compound over the years.
There's going to be some degree of measurement error, which will likely be greater for objects which have not been observed many times. Multiple observations should allow both better estimation of the object attributes (average out the noise), and allow some judgement of the quality of predictions given what you think you know about it.
If in 2032 an impact did occur, how much time before that impact would be able to ascertain over 50% probability of impact? hypothetically.
That is, does the certainty increase steadily or non-linearly over time? Does near certainty of an impact occur from measurements taken just minutes before the impact, or hours, days, years?
A slight tangent.. but my favorite thing about Horizons is that they still maintain a telnet interface to their system. Once you learn to use it it's quite a bit of fun to play around with it.
I wonder if we have a chance to catch it still on radar this pass. I know Arecibo used to do that and is now sadly gone, but Goldstone also has capability. Anyone know more?
I understand that we don't know the exact trajectory of the object, but there should be relatively little play on the time of (potential) impact, and the direction it would come from, so we should already know the orientation of the earth, and the spot on the earth where it would hit if we assumed the trajectory to pass through the center of the earth. The hemisphere centered around this position on the earth surface is then effectively candidate for the future potential impact, the rest of the earth surface would be obscured by the front hemispherical earth surface from the perspective of the object. Do you know where this center is?
I would expect that a handful of retroreflectors, along the lines of lunar laser ranging, would be much less expensive and work about as well if not better. A radio beacon can give direction, at least within the precision of whatever array is used to locate it, but it does not directly give distance. And, with a reflective system, you can get extremely precise radial velocity by measuring Doppler shift, and all the fancy equipment needed is right here on Earth where it’s easy to maintain and upgrade. Doppler measurements of a remote beacon are dependent on the quality of the remote clock, which adds complexity and dependence on gravitational redshift at the beacon [0].
[0] I haven’t tried to calculate how much this would offset the apparent velocity, but it seems very likely to at least be detectable.
I think that was supposed to be some kind of small black hole passing through the solar system or something more exotic. Maybe I'm misremembering.
Great book though and still haunts me sometimes when staring up at the night sky:)
An 8 MT impact on the Moon is what the Moon calls "Tuesday." It has dealt with far, far worse.
The impact probably wouldn't even be visible with the naked eye unless it hits a part of the Moon not then illuminated by the Sun -- in which case one might see a brief flash of light.
SE leaves the question of exactly what impacted the Moon unspecified, referring to it as the "agent". Both narratively and in-story, the question of what the ramifications of the event are is far more significant than its origin. It's not possible to change the past, nor does an understanding (narratively or in-story) have any appreciable impact on what transpires as a consequence.
As others have noted, an 8 MT impactor on the Moon would be a quite minor event. It would likely be visible to terrestrial observers (if on the near-side) and leave a visible crater. Might generate ejecta which itself could enter the Earth's atmosphere over time, though likely with little effect on the ground.
This is not an increase over baseline risk (as its Palermo scale[0] indicates, being a negative number, -0.56).
I think there's going to be a crisis of media going forwards, because with the very awesome new telescope[1] that's going online this year, the number of these detections is going to drastically go up. The number of objects isn't going up—they've always been there, we just didn't know—but I think the media coverage is not going to absorb that nuance very well.
[0] https://en.wikipedia.org/wiki/Palermo_Technical_Impact_Hazar... ("A rating of 0 means the hazard is equivalent to the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact)")
See also: https://en.wikipedia.org/wiki/Australasian_strewnfield (debris over 10% to 30% of the Earth's surface from an impact ~788,000 years ago). Smaller, for sure, but very recent and large enough for "nuclear winter" type scenarios.
(I worked tangentially on software for analyzing data that will come from the Vera Rubin telescope, and) yeah, while it was designed for spotting weird supernovae and such, the first half of its operation is expected to be dominated by the discovery of near earth objects.
So you're calling it a "crisis" that people will be better informed of the risk they've always faced? Seems to me we should use that media coverage to build political support for a real asteroid defense system.
If the media does not contextualize risks correctly, as it never does, it's absolutely a crisis—a crisis of a poorly-informed, panicked society lashing out and doing irrational things.
It's not a costless error if a warped illusion of risk drives countries to, i.e., deploy nuclear-tipped space weapons for asteroid defense, which then precipitate a genuine crisis. It's not obvious that having more defenses is obviously safer than having less; some thoughtful people have argued the opposite:
>"In our view, development of this asteroid-deflection technology would be premature. Given twentieth-century history and present global politics, it is hard to imagine guarantees against eventual misuse of an asteroid deflection system commensurate with the dangers such a system poses. Those who argue that it would be prudent to prevent catastrophic impacts with annual probabilities of 10^-5 would surely recognize the prudence of preventing more probable catastrophes of comparable magnitude from misuse of potentially apocalyptic technology."
This. It’s a crucial step for our civilisation to be able to protect earth from any incoming dangers be it asteroids or Umuamua type objects. There must be a global effort with all countries to build such a system.
> I think there's going to be a crisis of media going forwards
I take that as meaning a crisis of traditional media. But most of our false-positive and false-negative crises are crises of social media. Look at climate change, vaccines, ethnic hatred, pizza gate, every crazy rumor ...
Asteroids mostly contain the same naturally radioactive elements we find in Earth's rocks - mainly potassium, uranium, and thorium in very small amounts. When they hit Earth, they don't typically create radiation hazards. Scientists have checked out famous impact sites like Meteor Crater in Arizona and found normal radiation levels. While impacts can briefly create some radioactive isotopes through the collision process, it's really the impact's explosive force that does the real damage, not radiation.
Those numbers were a bit abstract to me, so to get an idea: Tungunska event (1908) is estimated between 3 and 5 [1], and the Chelyabinsk (2013) at 0.5 [2]
If you had a 100 ton spacecraft and you pumped all that kinetic energy into it with perfect efficiency, it would get up to 0.2% of light speed, fast enough to reach the nearest star in about 2000 years.
For reference the Tunguska event, which was projected to be a 5MT explosion on the low end, flattened about 2000 square kilometers when it airburst. If this hits the ocean it would no doubt cause some large tsunamis.
Only very locally, the Japan tsunami was an order of magnitude more energy and aiui earthquake tsunamis happen particularly with certain kinds of seafloor displacement. It's not just about the amount of energy but how that energy is applied, impact energies dissipate quickly with distance.
It depends, on where exactly will hit. Similar to nuclear explosions, if one happen over sea or ocean near coast, it will cause extremely large wave, which will be similar to tsunami. If it will hit land, will be small earthquake.
This is why nearly all nuclear explosions was over land or far from coast. Few experiments near some coast or island, created tsunami-like wave on those coast (island), which considerable widen polluted territory (ocean is usually considered as self-cleaning).
2032 Mayan prophecy + 2024 YR4 = prime fuel for internet-born doomsday cults.
"The final katun in the sequence that must happen before the new cycle of the katuns begins again is 13 Ahau. This starts in 2032 and ends in 2052. It is the time from 2032 to 2052, that great earth changes may take place.
The translation from the codices about 13 Ahau that starts in 2032 is ‘Famine, plagues of locusts, and loss of rulers. The judgment of God’ Mr. Scofield goes on to elaborate on this katun.
‘This is a time of total collapse where everything is lost. It is the time of the judgment of God. There will be epidemics and plagues and then famine. Governments will be lost to foreigners and wise men and prophets will be lost.‘
It is my perception that the great crisis that many fear in 2012 may well start after 2032. An interesting note to this time period is that it did bring great revolution and change during the time period from 1776 to 1796."
Mayans did not follow the Gregorian Calendar so our yearly dates don't match they already had their apocalypse in 1500s
"
This is a time of total collapse where everything is lost. It is the time of the judgment of God. There will be epidemics and plagues and then famine. Governments will be lost to foreigners and wise men and prophets will be lost.‘"
Completely out of my domain and seat of pants rationing here, but although the impact probability is 1%, aren't we far far more certain about the /time/ at which it would strike earth? Could humanity collectively just migrate to the side of the world that will be shielded for a day?
The bad news is no, we have nothing even remotely close to the infrastructure necessary to move half the world's population. We don't have the transport, being limited to planes and boats mostly.
The good news is that, worst-case scenario, this is going to wipe out a city. And cities and their surrounding areas can absolutely be evacuated. We definitely have the cars and buses necessary for that.
But in any case, we certainly have the logistics to move populations given the timeline. Not everyone has to evacuate and return within a 3 day window.
Even without incentives, in all likelihood, those who can will evacuate early for peace of mind, and as the prediction becomes more certain on its approach through measurement, individuals will I'm sure even start to return /before/ the pass. You know everyone has their own set of 9s to chase
Even if we had the infrastructural capacity to move hundreds of millions or billions of people for that amount of time (how many airplanes would you need? where would they all stay?) the political considerations would never be feasible. Think if the asteroid would hit Central America/Mexico, and think of the politics of moving them further north into North America.
If we run a simulation forward to, say, Jan 1 2032, our uncertainty about where the asteroid will be is not only in, let's call it, the X and Y axes, describing a flat circle of where the asteroid might be (see [1]), but also in a Z axis.
That is, our uncertainty of where the asteroid will be can be described as a 3D shape. And if it's further "behind" or "ahead" in its trajectory, then it would be passing through Earth's orbit behind or ahead of time.
Knowing the time doesn't tell you which side of the planet it will impact. The asteroid and the Earth are both moving. From the asteroid's perspective, it can get ahead of the earth and the Earth rear ends it, which from Earth's perspective is the asteroid hitting from the opposite direction that it's coming from.
Knowing humanity and its ability for planetary level solidarity, its more likely that the most powerful nations would simply displace the weaker ones. "No offence bro, but we are the salt of the Earth, so get out of here and good luck".
What about empty places? Luckily for Greenland, the calculations predict that the flux of impacts to the poles for Earth is 22% greater than the flux at the equator [1]. So nobody (in their right mind) would want to annex it as an asteroid survival backup site.
Readit News
Our knowledge of the diameter of this object is a bit fuzzy, because of surface reflectivity, small shiny things can appear as bright as dark large things. This is one of the motivations of making the NEO Surveyor an IR telescope, since IR we see black body emission off of the objects, which is mostly size dependent, and only weakly albedo dependent.
There is an even tinier chance that if it misses the Earth in 2032, it could hit the moon. I haven't run the numbers precisely for that one, but it impacted a few times in some monte-carlo simulations.
If anyone is interested in orbit dynamics, I have open sourced some of the engine we are using for observation predictions: https://github.com/Caltech-IPAC/kete
It is relatively high precision, though JPL Horizons has more accurate gravitational models and is far better suited for impact studies. My code is primarily for predicting when objects will be seen in telescopes.
Where does the uncertainty (1%) come from? For example, is it more from our ability to precisely determine the orbit based on limited observations, or is it because orbits for objects like this just aren't predictable years out, or something else?
Once you have an estimated orbit, if it has any interactions with planets (IE: flyby of Earth), small differences in positions during the close encounter make LARGE differences decades later. Add to this the effects of photons from the sun pushing on the smaller asteroids or dust, or out-gassing /dust from comets cause these objects to slightly drift from just the basic gravitational forces. Generally inner solar system asteroids (inside mars) are very chaotic over hundreds of years, though typically predictable less than a century.
Note that I am not an expert on impact calculations, I just know a bit about and and can do back of the envelope ones. There are a number of ways to get to the ~1%, the orbit fits have uncertainties on them and those can be propagated forward in time. However there are all sorts of complexities with doing that, and often the easiest method is to sample the uncertainty region a few hundred thousand times (Monte-carlo), and propagate those and see what hits.
That is, does the certainty increase steadily or non-linearly over time? Does near certainty of an impact occur from measurements taken just minutes before the impact, or hours, days, years?
If the object really looked like it might impact I'm sure someone would get time on a powerful telescope to lock in the orbit.
I understand it's hypothetical, but even a 10% chance of hitting a city, for example, would be a crisis.
A slight tangent.. but my favorite thing about Horizons is that they still maintain a telnet interface to their system. Once you learn to use it it's quite a bit of fun to play around with it.
[0] https://fast.bao.ac.cn/
[0] I haven’t tried to calculate how much this would offset the apparent velocity, but it seems very likely to at least be detectable.
Oh, that's not so ba--- Wait, isn't that what happens in Seveneves?
The impact probably wouldn't even be visible with the naked eye unless it hits a part of the Moon not then illuminated by the Sun -- in which case one might see a brief flash of light.
As others have noted, an 8 MT impactor on the Moon would be a quite minor event. It would likely be visible to terrestrial observers (if on the near-side) and leave a visible crater. Might generate ejecta which itself could enter the Earth's atmosphere over time, though likely with little effect on the ground.
Read that book over a year ago and it's still eating at me.
https://en.wikipedia.org/wiki/Yellowstone_Volcano_Observator...
How concerned? https://www.agiweb.org/geotimes/june05/feature_supervolcano.... not very.
I think there's going to be a crisis of media going forwards, because with the very awesome new telescope[1] that's going online this year, the number of these detections is going to drastically go up. The number of objects isn't going up—they've always been there, we just didn't know—but I think the media coverage is not going to absorb that nuance very well.
[0] https://en.wikipedia.org/wiki/Palermo_Technical_Impact_Hazar... ("A rating of 0 means the hazard is equivalent to the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact)")
[1] https://www.technologyreview.com/2025/01/01/1108643/vera-c-r... ("With its capacity to detect faint objects, [Vera] Rubin is expected to increase the number of known asteroids and comets by a factor of 10 to 100")
The universe is a big place with some big rocks in it. There are also some !!fun!! simulations of things like the Vredefort impact on YouTube.
It's not a costless error if a warped illusion of risk drives countries to, i.e., deploy nuclear-tipped space weapons for asteroid defense, which then precipitate a genuine crisis. It's not obvious that having more defenses is obviously safer than having less; some thoughtful people have argued the opposite:
>"In our view, development of this asteroid-deflection technology would be premature. Given twentieth-century history and present global politics, it is hard to imagine guarantees against eventual misuse of an asteroid deflection system commensurate with the dangers such a system poses. Those who argue that it would be prudent to prevent catastrophic impacts with annual probabilities of 10^-5 would surely recognize the prudence of preventing more probable catastrophes of comparable magnitude from misuse of potentially apocalyptic technology."
https://sci-hub.se/https://doi.org/10.1038/368501a0 ("Dangers of Asteroid Deflection" (1994), Carl Sagan & Steven Ostro)
I take that as meaning a crisis of traditional media. But most of our false-positive and false-negative crises are crises of social media. Look at climate change, vaccines, ethnic hatred, pizza gate, every crazy rumor ...
Dead Comment
I don't understand why this apt pun on that movie is being downvoted.
Would anyone of the downvoters of parent care to explain?
8.1 megatons of kinetic energy. According to the Torino rating, only risk of “localized destruction” (less than “regional devastation”): https://cneos.jpl.nasa.gov/sentry/torino_scale.html
https://en.wikipedia.org/wiki/B53_nuclear_bomb
Asteroids mostly contain the same naturally radioactive elements we find in Earth's rocks - mainly potassium, uranium, and thorium in very small amounts. When they hit Earth, they don't typically create radiation hazards. Scientists have checked out famous impact sites like Meteor Crater in Arizona and found normal radiation levels. While impacts can briefly create some radioactive isotopes through the collision process, it's really the impact's explosive force that does the real damage, not radiation.
[1] https://en.wikipedia.org/wiki/Tunguska_event [2] https://en.wikipedia.org/wiki/Chelyabinsk_meteor
I'm guessing there's still a lot of uncertainty.
Dead Comment
Parlermo Scale https://en.wikipedia.org/wiki/Palermo_Technical_Impact_Hazar...
Torino Scale https://en.wikipedia.org/wiki/Torino_scale
https://en.m.wikipedia.org/wiki/Tunguska_event
This is why nearly all nuclear explosions was over land or far from coast. Few experiments near some coast or island, created tsunami-like wave on those coast (island), which considerable widen polluted territory (ocean is usually considered as self-cleaning).
"The final katun in the sequence that must happen before the new cycle of the katuns begins again is 13 Ahau. This starts in 2032 and ends in 2052. It is the time from 2032 to 2052, that great earth changes may take place.
The translation from the codices about 13 Ahau that starts in 2032 is ‘Famine, plagues of locusts, and loss of rulers. The judgment of God’ Mr. Scofield goes on to elaborate on this katun.
‘This is a time of total collapse where everything is lost. It is the time of the judgment of God. There will be epidemics and plagues and then famine. Governments will be lost to foreigners and wise men and prophets will be lost.‘
It is my perception that the great crisis that many fear in 2012 may well start after 2032. An interesting note to this time period is that it did bring great revolution and change during the time period from 1776 to 1796."
https://www.tokenrock.com/mayan-astrology/2012-mayan-prophec...
" This is a time of total collapse where everything is lost. It is the time of the judgment of God. There will be epidemics and plagues and then famine. Governments will be lost to foreigners and wise men and prophets will be lost.‘"
The good news is that, worst-case scenario, this is going to wipe out a city. And cities and their surrounding areas can absolutely be evacuated. We definitely have the cars and buses necessary for that.
Even without incentives, in all likelihood, those who can will evacuate early for peace of mind, and as the prediction becomes more certain on its approach through measurement, individuals will I'm sure even start to return /before/ the pass. You know everyone has their own set of 9s to chase
If we run a simulation forward to, say, Jan 1 2032, our uncertainty about where the asteroid will be is not only in, let's call it, the X and Y axes, describing a flat circle of where the asteroid might be (see [1]), but also in a Z axis.
That is, our uncertainty of where the asteroid will be can be described as a 3D shape. And if it's further "behind" or "ahead" in its trajectory, then it would be passing through Earth's orbit behind or ahead of time.
1. https://en.wikipedia.org/wiki/Torino_scale#/media/File:Apoph...
Supposing we had a good estimate about time and place, it would be similar in scope to evacuating for a hurricane.
Spoiler: It's an XKCD What If, so lots and lots of people die.
What about empty places? Luckily for Greenland, the calculations predict that the flux of impacts to the poles for Earth is 22% greater than the flux at the equator [1]. So nobody (in their right mind) would want to annex it as an asteroid survival backup site.
[1] https://iopscience.iop.org/article/10.3847/PSJ/abefda/pdf