Shortest answer is that it depends heavily on things we don't quite know yet but should know soon. A 40-m YR4 will be < 10% the mass of a 90-m YR4, with an associated difference in the capability needed. Waiting a few weeks to get the JWST data and narrowing the uncertainties will be worth the wait.
Makes total sense. Given how even the upper-end mass estimates compare to Dimorphos and the delta-V that DART imparted, do we have even a rough sense of how much delta-V would need to be imparted to 2024 YR4 post-2029 to mitigate impact risk? Totally understand if premature.
I ask in this way because given the observation constraints on 2024 YR4, we'll lose sight of it from this summer until 2028, and if we launch an impactor in 2028, it could take until 2029 to collide based on DART as precedent.
I know that one big consideration is the internal structure of YR4: solid versus a rubble pile loosely held together by its own gravity.
There are a few factors here. I'll attach Figure 18-4 of the most recent Planetary Science Decadal Survey (nap.nationalacademies.org/read/26522/c...), which shows what mitigation techniques would be considered given a size and warning time, in a ballpark sense.
Where we are now is skirting the Civil Defense/Kinetic Impactor Disruption line. We didn't want to disrupt Dimorphos because we could end up with YR4-sized chunks, which wouldn't be fun if they hit somewhere. Disrupting YR4 would end up with pretty harmless pieces, if they happened to hit.
Very helpful, thanks! Interesting that we could be in the gray area between nuclear and kinetic.
Well, while I'm somewhat color blind so don't see quite where the red ends on that , I think there would be _strong_ motivation to avoid a nuclear anything. Hopefully this all remains online speculation rather than true policy consideration!
Certainly. More that based on the chart, I'm also uncertain on how far below the 5-year threshold civil defense kicks in. I have some reading to do!
Yeah, don't take the chart as super-quantitative, many details got smoothed out and lots of assumptions made to make it (not a criticism of it, of course!). But YR4 is in a place where if it ends up near the small end of expectations, letting it hit (the ocean) might be the right answer.
Makes total sense. That's one of the nice things that Earth gives us: Even if the impactor hits, there is a very good chance it hits water and doesn't, say, break apart above a major urban area.
As long as we're speculating—and this is speculation—it would be interesting to start work on a potential impactor mission that could be redirected into a reconnaissance flyby upon confirmation in 2028 that it won't hit Earth.
Yep, this isn't my department ("You want Mission Design, they're down the hall"), but I'm sure the usual suspects are already looking ahead in case they're asked for alternatives. I'm also sure this will all be discussed at this spring's Planetary Defense Conference in lovely Stellenbosch. :)
Yes, but few people know that excersise invented 2024 PDC25 case (yet)
From an asteroid or planetary science perspective, if it was confirmed to hit ocean... How much science value in letting it hit and putting every single instrument and GoPro in the general vicinity?
I don't see what Faroese football has to do with this (X) en.wikipedia.org/wiki/Klaksv%...
Just as KI reached historic highs in its recent Champions League results, YR4 is reaching historic highs in its Torino Scale figures. Next question. :)
"Espen Haug (born 30 January, 1970) is a Norwegian football coach. He is the current head coach of KÍ Klaksvik, and previously coached Drøbak/Frogn. In his active career he played for Strømmen, Vålerenga, Lyn, Ham-Kam and Hønefoss."
As fine a protagonist for "Armageddon II" as any. Better get him training on an oil derrick stat.
One thing I'm thinking about: NASA has already contracted for a solar electric propulsion module for the Lunar Gateway. Amid what are clearly broader Trump II rethinks of Artemis, could Gateway's Power and Propulsion Element (PPE) be modded to power a DART for YR4?
Understand you want to converse with pros like @asrivkin.bsky.social. But allow me also to recommend a Youtube clip from Scott Manley (@djsnm.extwitter.link) As a followup to his first video describing 2024 YR4, he describes a strawman deflection mission, with a good discussion of design issues.
Watching Scott Manley's exercise in asteroid-deflector mission planning may help you refine the questions you'd ask of asteroid specialists. I found it quite instructive. Scott focuses on the asteroid's December 2028 approach to the Earth as the best time for an impact mission.
For the curious, here's a link to the first of Scott Manley's pair of videos, in which he covers the basics of the potentially hazardous asteroid 2024 YR4. It's very good, but I expect @michaelgreshko.bsky.social is already familiar with the information it covers.