So newly discovered asteroid 2024 YR4 currently has something like a 1 in 63 chance of hitting the Earth. We will know for certain when it comes around in 2028. For an exercise, let say that asteroid 2024 YR4 will hit the Earth in 2032. What do we do?We don't know for sure but we think it is rocky, and between a half a football field and a whole football field in size. The effects would be larger than any asteroid strike in modern history. Not an extinction level event but could be pretty bad. What kind of mission would be best to insure the asteroid would cause no harm? Would we shove it, nuke it, hit it with mass at high speed? What would launch it. What would be the payload?
So if there is a catastrophic asteroid impact, it may be worthwhile to estimate the magnitude of damage and factor the probability of the event occurring…. Then compare that to another relevant option.Probability of impact : 1.9%Maximum economic losses: 0-5 trillionMaximum casualties: 0-10000Can a viable solution be developed and used before 2032 that saves 200 people for less than 100 billion? Ancient alien astronomers say yes:You just need to lease a bunch of busses and evacuate the population out of the impact area. It is cheaper to evacuate everyone on Earth.
Quote from: Mr. Scott on 02/06/2025 04:35 amSo if there is a catastrophic asteroid impact, it may be worthwhile to estimate the magnitude of damage and factor the probability of the event occurring…. Then compare that to another relevant option.Probability of impact : 1.9%Maximum economic losses: 0-5 trillionMaximum casualties: 0-10000Can a viable solution be developed and used before 2032 that saves 200 people for less than 100 billion? Ancient alien astronomers say yes:You just need to lease a bunch of busses and evacuate the population out of the impact area. It is cheaper to evacuate everyone on Earth.Your "maximum casualties" figure is IMO out by at least one order of magnitude.If the impact was in the sea, it could generate a substantial tsunami. If that was in the northern part of the Bay of Bengal, the tsunami would wash over the hugely densely populated Ganges delta in Bangladesh, and the casualties would be hundreds of thousands or even worse.If you look at the map here: https://www.reddit.com/r/MapPorn/comments/1idbby1/theres_a_12_chance_of_asteroid_2024_yr4_hitting/ there's a few places where the results of a sea impact could be catastrophic
If it's somewhere unpopulated, like the mid Atlantic, all that would be needed would be to warn people/boats/planes not to be there when it hits.
Ok people..calm down.. oi course the risk first rises as you refine with new data the trajectory where you cut the edges.. so purely due to mathematics the impact risk rises until the Earth drops out of the flight corridor and then the risk drops to zero.Addition: The chance that an asteroid will hit the Earth is 1, the chance a significant asteroid will hit Earth during one owns lifetime is nearly 0.
Any estimates on the tsunami risks? Would it be a Boxing Day-style event that would impact the entire ocean basin or something localized to a specific area?
I'm no expert, but Castle Bravo was 15 megatonnes, about twice the estimate for 2024 YR4, going off on an atoll in the middle of the Pacific, and the wiki article doesn't mention a tsunami of any size.
Will it be the old Soviet joke about What to do in case of nuclear war? (put on a sheet and walk slowly toward the graveyard so as not to cause mass hysteria.), or would it be a end-of-days survivalist nightmare of some hunkering down in bunkers in the boonies while the cities descend into chaos and the rich flee to their refuges in New Zealand?
Quote from: JAFO on 02/08/2025 05:26 pmWill it be the old Soviet joke about What to do in case of nuclear war? (put on a sheet and walk slowly toward the graveyard so as not to cause mass hysteria.), or would it be a end-of-days survivalist nightmare of some hunkering down in bunkers in the boonies while the cities descend into chaos and the rich flee to their refuges in New Zealand?Re-read Lucifer's Hammer.But remember that 2024 YR4 is not as big as the Hammer.
Scott Manley designs a mission to divert Asteroid 2024 YR4!
Couldn’t it theoretically be a good thing if it hit [an unpopulated area]? I do believe it has some useful metals. If it hits a populated area (unlikely), it would be really bad for them and the surrounding areas, but we could deflect it to an uninhabited area (or away from Earth, but let’s assume we want it to hit to see what’s in it).So once it hits an unpopulated area - let’s say in the Sahara, we could probably deflect it there. Miners would be sent out to crack open the asteroid, part would obviously be taken fir research, but this would be the first time we would be able to examine large quantities of a stony/ metallic asteroid. We could also use the information to start developing asteroid mining equipment. Also, any precious metals could be mined and used. Obviously this wouldn’t be one of those “quadrillion dollar asteroid”s, but it could probably be worth a few trillion, depending on how much gubbins there is in there.
Tunguska was a dusty asteroid though? Much more susceptible to breakup than a solid asteroid like 2024 YR4. Either way, if it does happen to reach the surface in (mostly) one piece…?
So given the possible impact time and date and orbital plan of the asteroid, the most likely impact area is shown here. https://www.reddit.com/r/MapPorn/comments/1idbby1/theres_a_12_chance_of_asteroid_2024_yr4_hitting/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button
The margin of uncertainty is many times bigger than the entire planet is. Any projection of impact location holds as much water as astrology does..
The effects of this unlucky collision would likely be visible from our planet — although we, ourselves, would probably be unaffected."There is the possibility this would eject some material back out that could hit the Earth, but I highly doubt it would cause any major threat," Rankin told New Scientist.That does not mean we wouldn't see it. Rankin told Live Science that, based on current estimates, a collision with the moon could release more energy than 340 Hiroshima bombs. "It would likely be very visible from Earth," he said.
Quote from: deadman1204 on 02/11/2025 07:13 pmThe margin of uncertainty is many times bigger than the entire planet is. Any projection of impact location holds as much water as astrology does..As I understand it, the extent of the uncertainty region is not the same in all directions. It's huge in one direction due to uncertainty in its exact arrival time. However, the uncertainty in the other directions is much less and sufficient to constrain the potential impact location to a relatively tight line across the earth in the unlikely event that a collision occurs.
Quote from: armchairfan on 02/11/2025 07:49 pmQuote from: deadman1204 on 02/11/2025 07:13 pmThe margin of uncertainty is many times bigger than the entire planet is. Any projection of impact location holds as much water as astrology does..As I understand it, the extent of the uncertainty region is not the same in all directions. It's huge in one direction due to uncertainty in its exact arrival time. However, the uncertainty in the other directions is much less and sufficient to constrain the potential impact location to a relatively tight line across the earth in the unlikely event that a collision occurs.Is there evidence for this? We know so little about its position and orbit, and orbit includes the inclination. We cannot assume its perfectly aligned with our equator. If you notice, that picture was just a red line across the equator, but conveniently skipping the entire pacific ocean. I would restate that any projected places that are more likely to be hit are utter bs at this point.
The line only covers half the earth, because it can only hit the side of the earth closest to the direction it's coming from, just like the possible places to see a solar eclipse will never be at night. The Pacific will be on the "leeward" side of the globe when the asteroid passes.
Quote from: Narnianknight on 02/14/2025 04:18 pmThe line only covers half the earth, because it can only hit the side of the earth closest to the direction it's coming from, just like the possible places to see a solar eclipse will never be at night. The Pacific will be on the "leeward" side of the globe when the asteroid passes.It's a bit more complicated than that because gravity bends trajectories. An asteroid with infinite C3 can only hit one half of the Earth. An asteroid with zero C3 (parabolic trajectory) can hit anywhere, including the "leeward" side of the planet. An asteroid with positive finite C3 can hit a portion of the Earth that's more than half but not all.
Hey NASA - National Aeronautics and Space Administration - Here is our plan to save the planet from 2024 YR4.Some context on 2024 YR4 - 2024 YR4 is estimated to be about 130 to 300 feet (40 – 90 meters) wide and has a very small chance (~2%) of Earth impact on Dec. 22, 2032. In the event the it does hit the Earth, it could release ~ 8 megatons of energy on impact — about 500 times more powerful than the devastating atomic bomb dropped on Hiroshima in Japan.It's low likelihood impact, but worth trying to prevent and we can do it. If we launch a craft in the middle of 2027, it will take us 1.5 years to travel to the asteroid. We can redirect it by impacting the asteroid with over 13.5 km/s relative velocity. Think Armageddon, but this time we don't need @BenAffleck. Still taking suggestions for a theme song though. Oh - and we can do this all for less then $20M.
3.1% chance of Earth impact1 in 32 odds of impact
The OHB experts have now also started to develop a mission plan for 2024 YR4. This is to ensure that the asteroid can be diverted in an emergency, and it is being examined whether previous designs of OHB missions to asteroids - such as Hera or Ramses - can be reused.Although it is very likely that the probability of impact for 2024 YR4 will also drop to 0 after further observation of the trajectory, if it increases instead, it is necessary to start developing a defense mission early. This is because the next - and best - launch opportunity for an impact probe will arise as early as 2028.
On 18 February 2025, the probability that asteroid 2024 YR4 might impact Earth on 22 December 2032, as assessed by ESA’s Near-Earth Object Coordination Centre, rose to 2.8%.This means that 2024 YR4 has now surpassed the 2.7% chance of impact briefly associated with the much larger asteroid (99942) Apophis back in 2004.For asteroids larger than 30 metres in size, 2024 YR4 now holds the record for the highest impact probability reached, and the longest time spent with an impact probability greater than 1%.
Now if we can get astronauts onboard the asteroid to ride it into EDL, then it could be one of the coolest moments in all of history. That’s one small splash for clams, one giant splash on mankind.
If the asteroid is already expected to air burst with nothing being done, doesn't that argue for trying to nuke it? Select impact so that the force redirects mass off course. But also to fracture it as much as possible. Send a series of nukes in sequence. Smaller fragments would burn up faster and likely nothing would reach the ground.A refueled Starship could Pez dispense them, each with their own ion thrusters, etc.
Quote from: sdsds on 02/19/2025 07:10 amIn American Roulette, the probability of hitting a single number is 1 in 38, or about 2.63%.Now back to asteroid impacts. The 17 December 2028 close approach will garner a lot of attention. What are the odds no one actually does anything before then?I think the odds are now 1-in-32 (3% or 0.03).
In American Roulette, the probability of hitting a single number is 1 in 38, or about 2.63%.Now back to asteroid impacts. The 17 December 2028 close approach will garner a lot of attention. What are the odds no one actually does anything before then?
Just imagine an 8 lane highway. You're standing on the second next line to the middle. One car is approaching you. You can't see it yet. So the chance you'll get hit is 1/8th. Now the car is on the horizon. You can exclude the outer 2 lanes. So the chance you'll get hit is 1/6th.Wait a bit until the car is closer. You can exclude the next 2 outer lanes. The chance you'll get hit is now 1/4th. The car gets closer and you see it's driving on the inner lane. The chance you'll get hit drops to 0.Or simply said: until we get a usable trajectory of that asteroid, all numbers published in general media are click-bait.
This rock is about the size of the Leaning Tower, so a significant nuke could fracture it well into a thousand small size that will burn up. But then there are all those pesky satellites orbiting Earth that could get hit by the fragments, and you have another Movie called "Gravity."
Quote from: deadman1204 on 02/13/2025 06:59 pmQuote from: armchairfan on 02/11/2025 07:49 pmQuote from: deadman1204 on 02/11/2025 07:13 pmThe margin of uncertainty is many times bigger than the entire planet is. Any projection of impact location holds as much water as astrology does..As I understand it, the extent of the uncertainty region is not the same in all directions. It's huge in one direction due to uncertainty in its exact arrival time. However, the uncertainty in the other directions is much less and sufficient to constrain the potential impact location to a relatively tight line across the earth in the unlikely event that a collision occurs.Is there evidence for this? We know so little about its position and orbit, and orbit includes the inclination. We cannot assume its perfectly aligned with our equator. If you notice, that picture was just a red line across the equator, but conveniently skipping the entire pacific ocean. I would restate that any projected places that are more likely to be hit are utter bs at this point. The evidence is the astrometric measurements from a 45 day span. Your conjecture that it’s just a line along half the equator is incorrect.Please stop this nonsense.There is no reason to doubt the collection of orbit fits and impact probabilities from JPL, ESA, and others.Check out the Wikipedia page to see the JPL predictions and their evolutionFor the last five or so days the Moon has been too bright and close to take more images, it notes. After it moves away, and a few more images are obtained, the uncertainty will diminish greatly. Then Webb will get infrared images in March and April and the orbit and size will be much more accurately known.Maybe we will need to take the “For an exercise “ out of the thread title. edit on Feb 17: The first prediction has already come true. Five additional observations have reduced the uncertainty by a third. However, the predicted miss distance decreased, too, so the probability of impact increased from 2.2% to 2.6%.
Quote from: StarshipTrooper on 02/04/2025 05:16 pmSo newly discovered asteroid 2024 YR4 currently has something like a 1 in 63 chance of hitting the Earth. We will know for certain when it comes around in 2028. For an exercise, let say that asteroid 2024 YR4 will hit the Earth in 2032. What do we do?We don't know for sure but we think it is rocky, and between a half a football field and a whole football field in size. The effects would be larger than any asteroid strike in modern history. Not an extinction level event but could be pretty bad. What kind of mission would be best to insure the asteroid would cause no harm? Would we shove it, nuke it, hit it with mass at high speed? What would launch it. What would be the payload? You have seen read about the DART mission:https://forum.nasaspaceflight.com/index.php?topic=47874.msg2462515#msg2462515
Worth mentioning Dimorphos was slightly larger than 2024 YR4, and we were still able to impact its orbit around its parent body.
Ars: NASA's DART mission successfully shifted an asteroid's orbit in 2022. Could this technology be used?Andrews: Not necessarily. DART—a type of spacecraft called a kinetic impactor—was a great success. But it still only changed Dimorphos' orbit by a small amount. Ideally, you want many years of advance notice to deflect an asteroid with something like DART to ensure the asteroid has moved out of Earth’s way. I've often been told that at least 10 years prior to impact is best if you want to be sure to deflect a city killing-size asteroid. That’s not to say deflection is impossible; it just becomes trickier to pull off. You can’t just hit it with a colossal spacecraft, because you may fragment it into several still-dangerously sized pieces. Hit it too softly, and it will still hit Earth, but somewhere that wasn’t originally going to be hit. You have to be super careful here.Some rather clever scientists at the Lawrence Livermore National Laboratory (which has a superb planetary defense contingent) worked out that, for a 90-meter asteroid, you need 10 years to confidently deflect it with a kinetic impactor to prevent an Earth impact. So, to deflect 2024 YR4, if it’s 90 meters long and we have just a few years of time, we’d probably need a bigger impactor spacecraft (but don’t break it!)—or we’d need several kinetic impactors to deflect it (but each has to work perfectly).Eight years until impact is a little tight. It’s not impossible that the choice would be made to use a nuclear weapon to deflect it; this could be very awkward geopolitically, but a nuke would impart a bigger deflection than an equivalent DART-like spacecraft. Or, maybe, they’d opt to try and vaporize the asteroid with something like a 1 megaton nuke, which LLNL says would work with an asteroid this size.
Now that skies are darker after a week of limited visibility around full moon, astronomers have resumed observations of asteroid 2024 YR4. Ground-based telescopes require dark skies to observe asteroids, which are often very faint. Around the time of a full moon, the sky becomes too bright to detect these faint points of light.NASA’s Center for Near-Earth Object Studies at the agency’s Jet Propulsion Laboratory in Southern California has incorporated the new observations reported to the Minor Planet Center and on Feb. 18, updated the impact probability of asteroid 2024 YR4 in 2032 to 3.1%. This is the highest impact probability NASA has ever recorded for an object of this size or larger. However, on Wednesday, Feb. 19, new data collected overnight reduced the impact probability to 1.5%.Each additional night of observations improves our understanding of where the asteroid could be on Dec. 22, 2032 and underlines the importance of gathering enough data so that our planetary defense experts can determine future risk to the Earth. NASA expects the impact probability to continue to evolve as new observations of asteroid 2024 YR4 are made over the coming days and weeks.These recent observations have further constrained the uncertainty around the asteroid’s trajectory, and the yellow dots in the above graphics represent possible locations of the asteroid on Dec. 22, 2032. As we continue to observe the asteroid’s motion over time, the region of possible locations will shrink even further. For the impact probability to drop to zero, the Earth would need to fall outside of the range of potential locations of asteroid 2024 YR4 on Dec. 22, 2032.Additionally, there is also a – much lower — chance this asteroid could impact the Moon. Current calculations estimate this impact probability to be 0.8%.
Quote from: Comga on 02/14/2025 10:39 pmQuote from: deadman1204 on 02/13/2025 06:59 pmQuote from: armchairfan on 02/11/2025 07:49 pmQuote from: deadman1204 on 02/11/2025 07:13 pmThe margin of uncertainty is many times bigger than the entire planet is. Any projection of impact location holds as much water as astrology does..As I understand it, the extent of the uncertainty region is not the same in all directions. It's huge in one direction due to uncertainty in its exact arrival time. However, the uncertainty in the other directions is much less and sufficient to constrain the potential impact location to a relatively tight line across the earth in the unlikely event that a collision occurs.Is there evidence for this? We know so little about its position and orbit, and orbit includes the inclination. We cannot assume its perfectly aligned with our equator. If you notice, that picture was just a red line across the equator, but conveniently skipping the entire pacific ocean. I would restate that any projected places that are more likely to be hit are utter bs at this point. The evidence is the astrometric measurements from a 45 day span. Your conjecture that it’s just a line along half the equator is incorrect.Please stop this nonsense.There is no reason to doubt the collection of orbit fits and impact probabilities from JPL, ESA, and others.Check out the Wikipedia page to see the JPL predictions and their evolutionFor the last five or so days the Moon has been too bright and close to take more images, it notes. After it moves away, and a few more images are obtained, the uncertainty will diminish greatly. Then Webb will get infrared images in March and April and the orbit and size will be much more accurately known.Maybe we will need to take the “For an exercise “ out of the thread title. edit on Feb 17: The first prediction has already come true. Five additional observations have reduced the uncertainty by a third. However, the predicted miss distance decreased, too, so the probability of impact increased from 2.2% to 2.6%.Ahh yes, anything you disagree with must be nonsense. Again, margin of uncertainty is many many times larger than the entire planet. But its nonsense to say specific impact points are bogus, right?ESA, NASA, ect are all saying there's a chance, but then they go on to say they REALLY don't know precisely, and the margins on their data are significant. Surely its just nonsense to point out the details of the data they are providing are meaningful?The nonsense is with you disregarding facts you do not like
Which forum section does planetary defense belong in, i.e. asteroids and comets that may impact Earth and missions to predict or prevent such impacts? Planetary defense shouldn't be confused with the similarly named topic of planetary protection, which is unrelated. Planetary defense includes NASA's Planetary Defense Coordination Office (PDCO), missions such as NEO Surveyor, and asteroid 2024 YR4. The goal of planetary defense is protecting lives and assets, not acquiring knowledge, so planetary defense is engineering, not science. None of the sections seem to fit, so maybe "general discussion"? Should we create a dedicated Planetary Defense section?I ask because there's a thread in the "Missions To The Near Earth Asteroids (HSF)" section on asteroid 2024 YR4 (https://forum.nasaspaceflight.com/index.php?topic=62382.0) which presumably belongs elsewhere since asteroid redirect missions are almost certainly going to be uncrewed.
Observations made overnight on Feb. 19 – 20 of asteroid 2024 YR4 have further decreased its chance of Earth impact on Dec. 22, 2032, to 0.28%. NASA’s planetary defense teams will continue to monitor the asteroid to improve our predictions of the asteroid’s trajectory. With this new data, the chance of an impact with the Moon increased slightly to 1%.
Aww, that's no fun. Let's nuke it anyway for practice.
Quote from: Norm38 on 02/21/2025 04:43 pmAww, that's no fun. Let's nuke it anyway for practice.See if we can steer it back on?
And now, the nail in the coffinAnother good night, with 14 observations, sends the 3-σ uncertainty below the slightly increased miss distance.JPL Horizon probability of impact is now 1 in 26,000 or 0.004% and it falls to zero on the Torino Scale of impact risk.
Great news! This should end the thread for now until new information arises or a new thread is created as we approach 2032.
There still remains a very small chance for asteroid 2024 YR4 to impact the Moon on Dec. 22, 2032. That probability is currently 1.7%.
Planned observations of 2024 YR4 using the NASA/ESA/CSA James Webb Space Telescope will go ahead in the coming months to test the telescope’s ability to improve our estimate of the asteroid’s size.
While observers and satellites have seen many impacts on the Moon by small asteroids over the years, they’re sporadic, producing an occasional flash. “But this would be a predictable impact of some size,” Binzel tells Sky & Telescope. “We could have all our capabilities trained on the very spot of impact and watch this natural experiment unfold before our eyes.”Mark Boslough (University of New Mexico) is likewise intrigued by the possibilities. “We could send all kinds of observational missions to the Moon: seismometers, debris trackers, and imagers, and all sorts of instruments.”If the asteroid did hit the moon, Boslough says, based on the uncertainty in its size, it could leave a crater anywhere from about 400 meters across to as much as 1.8 km. across -- larger than Arizona's Meteor Crater.
How is it even possible to tell if a space rock will one day collide with the Earth?
This thread isn't about crewed spaceflight so it doesn't belong in this section of the forum. However I'm not sure what the correct section is so I posted in the rules section asking where a better home would be.
i find myself wishing the chance of impact didn't change to essentially zero. A short but not immediate threat is exactly what the globe needs to take planetary defense seriously.
Quote from: deadman1204 on 02/25/2025 06:11 pmi find myself wishing the chance of impact didn't change to essentially zero. A short but not immediate threat is exactly what the globe needs to take planetary defense seriously. For HHGTTG readers, when will the chances of impact reach one in a million?
Latest Calculations Conclude Asteroid 2024 YR4 Now Poses No Significant Threat to Earth in 2032 and Beyond [Feb 24]QuoteThere still remains a very small chance for asteroid 2024 YR4 to impact the Moon on Dec. 22, 2032. That probability is currently 1.7%.QuoteWhile observers and satellites have seen many impacts on the Moon by small asteroids over the years, they’re sporadic, producing an occasional flash. “But this would be a predictable impact of some size,” Binzel tells Sky & Telescope. “We could have all our capabilities trained on the very spot of impact and watch this natural experiment unfold before our eyes.”
While observers and satellites have seen many impacts on the Moon by small asteroids over the years, they’re sporadic, producing an occasional flash. “But this would be a predictable impact of some size,” Binzel tells Sky & Telescope. “We could have all our capabilities trained on the very spot of impact and watch this natural experiment unfold before our eyes.”
NASA’s James Webb Space Telescope recently turned its watchful eye toward asteroid 2024 YR4, which we now know poses no significant threat to Earth in 2032 and beyond.We spoke with Andy Rivkin of the Johns Hopkins University Applied Physics Laboratory, the principal investigator of the Webb Director’s Discretionary Time program used to study the asteroid’s characteristics from the observations.What is important for people to know about these Webb observations?While earlier in the year asteroid 2024 YR4 posed a potential future impact threat to Earth in 2032, by the end of February, NASA announced the risk of Earth impact had been significantly lowered to near-zero. Nevertheless, we are interested in using the observatory to measure its properties to understand what asteroids of this size are like to help inform the hazard they could pose to Earth. This is the smallest object targeted by the mission to date, and one of the smallest objects to have its size directly measured.Why did you request to use both NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) in this investigation? What did each tell you?Most telescopes observe asteroids by measuring sunlight reflected from their surfaces, and it’s hard to precisely determine their sizes from this information. At mid-infrared wavelengths like those used by MIRI, however, the heat given off by asteroids themselves can be measured and used to directly give the asteroid’s size. The NIRCam data covers the reflected light, and using it along with the MIRI data gives us not only the size but also a measure of how reflective its surface is, which is related to the asteroid’s composition.The chance of Asteroid 2024 YR hitting Earth in 2032 has greatly decreased, according to NASA’s Planetary Defense Coordination Office. Why are these observations still important?While we are confident that 2024 YR4 will not hit Earth in 2032, there is still great value in making these observations and analyzing the results. We expect more possible impactors to be found in coming years as more sensitive asteroid search programs begin operation. Observations using the most powerful telescope we have right now are invaluable. Understanding the best ways to use it and how to get the most out of its data is something we can do now with 2024 YR4. This will help us determine the best approach to use during a more urgent observing program should another asteroid pose a potential impact threat in the future.What have you learned? Was there anything surprising about the data?We found that the thermal properties of 2024 YR4, in other words how quickly it heats up and cools down, and how hot it is at its current distance from the Sun, are not like what we see in larger asteroids. We think this is likely a combination of its very fast spin and a lack of fine-grained sand on its surface. We’ll need more data to say for sure, but it seems consistent with a surface dominated by rocks that are maybe fist-sized or larger. And of course, our main goal was measuring the size of 2024 YR4, which we estimate at about 60 meters (200 feet). That’s just about the height of a 15-story building.How do the Webb observations fit within the larger picture of the study of this asteroid (and other near-Earth asteroids)?2024 YR4 and other near-Earth asteroids are studied by NASA’s planetary defense program and the international community of astronomers, orbit calculators, and impact physicists, among other scientists involved in the International Asteroid Warning Network. The new observations from this observatory not only provide unique information about 2024 YR4’s size. They also added to ground-based observations of 2024 YR4’s position to help improve our knowledge of its orbit and future trajectory. Some colleagues were also able to use other telescopes to make measurements of 2024 YR4’s spin rate and spectral properties shortly after it was discovered. All together, we have a better sense of what this building-sized asteroid is like. This in turn gives us a window to understand what other objects the size of 2024 YR4 are like, including the next one that might be heading our way!
Since near-Earth asteroid 2024 YR4 was first discovered in December 2024, NASA and the worldwide planetary defense community have continued to observe the asteroid, which was ruled out as a significant impact risk to Earth. New infrared observations from NASA’s James Webb Space Telescope have decreased the uncertainty of the asteroid’s size and 2024 YR4 is now estimated to be 174-220 feet (53-67 meters), about the size of a 10-story building. The previous size estimate of 131-295 feet (40-90 meters) was derived from visible light measurements from ground-based telescopes. Experts at NASA’s Center for Near Earth Object Studies at the agency’s Jet Propulsion Laboratory have updated 2024 YR4’s chance of impacting the Moon on Dec. 22, 2032 from 1.7% as of late February to 3.8% based on the Webb data and observations from ground-based telescopes. There is still a 96.2% chance that the asteroid will miss the Moon. In the small chance that the asteroid were to impact, it would not alter the Moon’s orbit. After mid-April, asteroid 2024 YR4 will be too far and faint to be observed by ground-based telescopes but Webb will observe the asteroid again in May.
What sort of tether do you think could influence the velocity of a trillion tonnes of rock.
While asteroid 2024 YR4 is currently too distant to detect with telescopes from Earth, NASA’s James Webb Space Telescope collected one more observation of the asteroid before it escaped from view in its orbit around the Sun. With the additional data, experts from NASA’s Center for Near Earth Object Studies at the agency’s Jet Propulsion Laboratory in Southern California further refined the asteroid’s orbit. The Webb data improved our knowledge of where the asteroid will be on Dec. 22, 2032, by nearly 20%. As result, the asteroid’s probability of impacting the Moon has slightly increased from 3.8% to 4.3%. In the small chance that the asteroid were to impact, it would not alter the Moon’s orbit.[...]NASA expects to make further observations when the asteroid’s orbit around the Sun brings it back into the vicinity of Earth in 2028.
On 2032 December 22 the 60m diameter asteroid 2024 YR4 has a 4% chance of impacting the Moon.Such an impact would release 6.5 MT TNT equivalent energy and produce a ∼ 1 km diameter crater.We estimate that up to 108 kg of lunar material could be liberated in such an impact by exceeding lunar escape speed. Depending on the actual impact location on the Moon as much as 10% of this material may accrete to the Earth on timescales of a few days. The lunar ejecta-associated particle fluence at 0.1 - 10 mm sizes could produce upwards of years to of order a decade of equivalent background meteoroid impact exposure to satellites in near-Earth space late in 2032. Our results demonstrate that planetary defense considerations should be more broadly extended to cis-lunar space and not confined solely to near-Earth space.
ConclusionIn this work, we have provided an overview of deflection and robust disruption mechanics and techniques, with an emphasis on impulsive techniques utilizing Kinetic Impactors (KIs) or standoff detonation of Nuclear Explosive Devices (NEDs). We have described the notional requirements for deflection or robust disruption of 2024 YR4, based on current knowledge and accounting for current uncertainties in asteroid physical properties (principally mass), lunar impact location (should the asteroid indeed be on a lunar-impacting trajectory), and deflection/disruption system performance (e.g., the momentum enhancement factor, β, for KIs). We have analyzed and discussed spacecraft mission trajectory options for flyby reconnaissance, rendezvous reconnaissance, deflection, and robust disruption. We have also generated exemplar mission campaign options based on the trajectory analysis results, noting key dates and discussing when associated decisions would need to be made in order for missions to be deployed. The best reconnaissance mission options launch in late 2028, leaving only approximately three years for development at the time of this writing in August 2025. Deflection missions were assessed and appear impractical. However, kinetic robust disruption missions are available with launches between April 2030 and April 2032. Nuclear robust disruption missions are also available with launches between late 2029 and late 2031.
Future JWST observations scheduled for early 2026 will further refine the orbit and may reduce the impact probability. Regardless of the outcome, this case illustrates how next-generation survey telescopes and infrared assets, such as JWST, transform planetary defense from an Earth-only effort to a whole Earth–Moon system strategy.
