This is a story of how a space enthusiast, equipped with just a phone, correctly predicted that NASA / DART's 15 m crater prediction for asteroid Dimorphos was wrong & unrealistically low. NASA's 15 m prediction had the benefit of expensive computers, expensive simulation software, physical experiments & a team of highly qualified scientists. Yet, I was ahead of NASA by almost 7 months, despite having no formal training in such topics (fully self-taught) or a team to help me.
Also, my prediction of over 40 m crater (made 20 days BEFORE impact) & 40-80 m crater (made 12 days AFTER impact), has turned out to be very realistic, in light of DART revising their pre-impact prediction from 15 m to 40-60 m crater, 6 months after impact, in March 2023. All supporting Twitter threads are documented below, with the date & time stamps. I came to know about DART's revised prediction only recently, though it was made public in March 2023, at a conference.
Twitter Thread, Alternate experience of same thread
NASA's DART mission to binary asteroids Didymos (bigger) & Dimorphos (smaller) was designed to test asteroid deflection technology by smashing a 2 m spacecraft head-on into Dimorphos, a moon of Didymos. It successfully slowed it down & reduced its orbit, on Sept 26, 2022.
While NASA supports & acknowledges the role of citizen scientists in the progression of science, I have noticed a very strange silence from the DART & NASA teams on Twitter, regarding my very accurate prediction (of 15 m crater being wrong) & a realistic prediction (40-80 m).
Timeline overview of my predictions vs NASA. In early 2027, we will know if these predictions were right, when ESA's Hera mission reaches the binary asteroids Didymos & Dimorphos & studies them both from orbit.
There has been zero acknowledgement & engagement from NASA/DART on this, on Twitter. Not even a public admission that their 15 m crater prediction was wrong, after seeing the post-impact evidence, weeks later.
Twitter threads & sub-threads are given below for verification (needs a Twitter login to see threads, else only 1 tweet will be visible) :
DART team's pre-impact prediction of 15 m crater :
https://twitter.com/schmemela/status/1123658653167493126?s=20
My prediction about DART's prediction being wrong :
https://twitter.com/VinnyChirayil/status/1577707893377314816?s=20
Why I felt it is wrong :
https://twitter.com/VinnyChirayil/status/1571504705632894976?s=20
Compared to JAXA's impactor on the 900 m wide asteroid Ryugu (which made a 14.5 m crater), NASA's impactor on the 160 m wide asteroid Dimorphos was :
- 3 times faster (6 km/s vs 2 km/s)
- 27 times larger (2 m vs 0.073 m)
- 250 times more mass (500 kg vs 2 kg)
By what logic & physics, was NASA expecting a tiny 15 m crater for their MUCH faster, bigger & heavier impactor, on a very small asteroid, with very weak gravity ?
My prediction of above 40 m crater (made 20 days BEFORE impact) :
https://twitter.com/VinnyChirayil/status/1567091412944191491?s=20
My refined prediction of 40-80 m crater (made 12 days AFTER impact) :
Crater depth range : 8-15 m
https://twitter.com/VinnyChirayil/status/1578794038546743297?s=20
Why I predicted such a high number for crater diameter :
https://twitter.com/VinnyChirayil/status/1567042109152333824
NASA / DART team's revised prediction of 40-60 m crater :
(made verbally only, 6 months after impact & stunningly close to my prediction, which was made just 12 days after impact) :
https://twitter.com/VinnyChirayil/status/1666656552210808834?s=20
DART's revised prediction proves right my prediction that their 15 m crater was very wrong.
Which means that the simulation software, models & physical experiments were all wrong. NASA's revised prediction of 40-60 m is a HUGE leap from 15 m, and interestingly, they now consider it as only a minimum size ; it can be even bigger.
Proof of NASA's 40-60 m crater prediction being the minimum size :
https://twitter.com/VinnyChirayil/status/1682720245524619270?s=20
"For comparison, the DART ... tentatively estimate a minimum crater diameter of 40–60 m (Stickle et al. 2023)"
'Stickle et al' is a paper by Dr. Angela Stickle, who is the impact expert of NASA's DART team.
Story does not end here. The June 2023 paper by Dr. Angela Stickle et al (mentioned above), admitted that the DART team's 40-60 m prediction was the bare MINIMUM & that it could be so big that a crater is no longer visible, due to shape deformation of the entire asteroid. This is the 2nd highest possible level of damage, the highest being destruction of the asteriod via fragmentation, a scenario which the DART team had very clearly ruled out in 2019, saying the spacecraft does not that much energy.
"... crater diameter could measure from 40-60 m to a larger basin-style reshaping of Dimorphos"
But on March 13, 2023, another paper by Dr. Angela Stickle refrained from giving any crater size estimate, despite mentioning 'crater size' in the title.
On the same day, at the DART press conference, she verbally shared NASA's crater prediction of 40-60 m, in this video below :
It is very strange that the crater prediction of 40-60 m was omitted from her paper. Also, note in the video, that there is no mention of the crater being bigger than that. It clearly implies that 40 m is the minimum & 60 m is the maximum.
Summary of NASA's crater prediction for asteroid Dimorphos :
May 2019 : 15 m crater
(Sept 26, 2022 : DART spacecraft impacts asteroid Dimorphos)
March 2023 : 40-60 m crater
June 2023 : minimum 40-60 m crater, to a massive damage of craterless global shape deformation of the entire asteroid.
In just 3 months, NASA's confidence in 40-60 m crater crumbled, forcing them to stretch their prediction to even more massive damage. When you make multiple predictions & epic deviations, from 15 m crater to 40-60 m crater to full shape deformation of the asteroid, then you cannot go wrong. One of those scenarios WILL be true, but anybody can do this & does not need any sort of expertise at all.
Even 2 months after impact, in early Dec 2022, impact simulation experts Dr. Sabina Raducan (DART & Hera mission) & Dr. Yun Zhang were both silent, when asked if the 15 m crater prediction was wrong, in light of new post-impact evidences. Silence means uncertainty. I was certain of it before impact & super certain, after impact. Also, I had specifically asked Dr. Sabina earlier, if she was in agreement when DART had predicted a 15 m crater in 2019. Her silence only confirmed my suspicion that she was in agreement. Both scientists had responded to me in the past, on other tweets. So their sudden silence was strange.
— https://twitter.com/VinnyChirayil/status/1674462732551356416?s=20
— https://twitter.com/VinnyChirayil/status/1600915181181161472?s=20
Other aspects of the story :
1) No prediction for crater depth : NASA & DART have given only an incomplete prediction till now, after almost 10 months from impact. A crater has to have depth also. I have predicted a depth range also (8-15 m), while NASA has still not given any. Usually, the 1:10 rule applies, implying a 1 m depth for a 10 m crater. Going by this, NASA's 40-60 m crater should have a depth of 4-6 m. Does NASA/DART agree with this or do they have a different depth prediction ? On Bennu, NASA measured both crater width & depth of natural craters & studied the ratio. So NASA's total silence on depth prediction for the artificial crater on asteroid Dimorphos is rather strange. I cannot imagine crater depth not being important for other teams like the Bennu team. Is DART not interested in predicting the full extent of damage caused, after having so much post-impact info ? Even the simulations run before impact, had considered crater depth. I wonder what reason could be stopping the DART team from predicting a depth range for a crater created by their own spacecraft. A crater is meaningless without depth.
2) Natural craters on Dimorphos : NASA / DART have also been silent on the 9 big craters I have identified on asteroid Dimorphos, from pre-impact pics, despite notifying them of it, on Twitter :
https://twitter.com/VinnyChirayil/status/1579766589217705985?s=20
While my confidence level on them varies from low to high, there are indeed some unmistakable craters. NASA's silence on this aspect is again extremely surprising, considering that the Bennu team was able to identify many craters on a similar terrain, although not as rough. Has the more experienced Bennu team analyzed Dimorphos photos ? Does DART team feel there were no recognizable natural craters on Dimorphos, before impact ?
I am surprised that DART team has been unable to identify even 1 crater on Dimorphos in the pre-impact photos, even after 6 months from impact.
Context : https://arxiv.org/abs/2303.02248 (March 2023)
"No unambiguous impact crater candidates are observed (on Dimorphos), which indicates a young surface, though craters can be difficult to identify on boulder-covered terrains"
If a space enthusiast like me can identify some strong candidates for craters there, then the struggle of the experts is quite surprising.
3) Evidence of stretch deformation on Didymos : There is an unmistakable signature of stretching on it, very similar to what is seen on comet 67P & to a far lesser extent on asteroid Ryugu. I consider the evolutionary phases of stretch looking like this : Bennu --> Ryugu --> Didymos --> 67P / Hartley2. Didymos was a crucial missing link in the pattern, showing an intermediate stage. Threads :
— https://twitter.com/VinnyChirayil/status/1581999007475281920?s=20
— https://twitter.com/MarcoParigi1/status/1576161411541000193?s=20
4) Why DART caused so much damage : I have also explained that perhaps DART behaved like a giant hollow point bullet. The massive damage caused is probably not because Dimorphos is a loose rubble pile with low gravity & strength. Thats true only for the surface layer / outer skin. Below the surface, Ryugu has shown strong cementing & is most likely the case for Dimorphos too. On Ryugu, JAXA's impactor barely moved some of the half buried boulders.
Thread on hollow point bullet effect :
https://twitter.com/VinnyChirayil/status/1589479765756743680?s=20
No comments:
Post a Comment