When I was watching the show I was wondering why they did not put a second probe right behind the first to observe the impact.
And when I went looking for more information about DART it turns out they did. the LICIACube. very cool.
So now the question is why was this not mentioned in the nasa show(perhaps I missed it) and why have I not heard anything about LICIACube from anywhere else(perhaps I missed this as well).
did LICIACube fail and every one is being quiet about it?
It worked, it’s just a very small machine with an equivalently small transmitting antenna, so even with the big dishes of the deep space network it’s going to be a while before we get all the data back. We have some data already https://www.ssdc.asi.it/liciacube/ and more is on the way!
You can find the images in a few different articles (though I wouldn't be surprised if science journalists failed to specify this), as well as on NASA's website [0].
It worked, and it's mentioned in the article: "the 'really impressive' Webb and Hubble images were remarkably similar to those taken by the toaster-sized satellite LICIACube, which was just 50 kilometres from the asteroid after separating from the DART spacecraft a few weeks ago."
My understanding is that we've known for a long time that they range from a sooty snowball to a single chunk of pitted iron alloy. Looks like this one was a softie.
That’s true, but I’m thinking that every class of asteroid is going to go down a level or two on the scale once we actually go poke them. Look at Bennu: they expected from the estimated density that it was a conglomerate and would have a significant amount of surface sand and dust they could pick up.
Close up pictures showed that it is a lot less homogeneous than they expected, with huge boulders right on the surface as well. That doesn’t match with the measured mass and density since boulders are heavy and dense, but maybe there are more internal voids. But then when they touched it, the nitrogen gas that was supposed to blow some dust and sand into the collection chamber also threw a huge amount of material out and away from the probe. It may even have shattered some of the gravel, meaning that stuff is really more like styrofoam. It may still be silicates, but it is probably foamy. Think of pumice rather than sandstone or granite. Those giant boulders might be more like stage props than actual boulders. It will be very interesting to see what that stuff looks like when they get the samples back.
All those stories of hollowing out an asteroid and turning it into a habitat or generation ship for 50,000 people aren’t looking so prescient. :)
Of course on the other hand it could turn out to just be selection bias: sample return missions are obviously going to pick a low–density asteroid that they hope will at least have some dust they can scoop up, instead of picking a really dense one that might turn out to be too difficult to collect from.
Also, I’m ignoring the dwarf planets that happen to be in the asteroid belt, like Ceres. We can reasonably expect them to have some real rocks.
> All those stories of hollowing out an asteroid and turning it into a habitat or generation ship for 50,000 people aren’t looking so prescient. :)
It would be very interesting to figure out how far away we are from the technology to send a "Seed" probe to a large conglomerate asteroid, designed to replicate itself into thousands of builder-bots. Then the builders would slowly but surely turn the asteroid into millions of assembler-chunks consisting of layers of concrete and metal. Then those assemblers would connect to each other, turning into sections of habitat hull.
Basically do it like Mother Nature does it: tiny building blocks that self-assemble into bigger building blocks that self-assemble into bigger building blocks, over and over. In other words, proteins into DNA/lipids/etc, DNA/lipids/etc into organelles, organelles into cells, cells into muscles/organs/etc. Not saying it would be squelchy organic technology, just that the process would look similar from a high level. Maybe it would look like self-assembling Lego!
Seed probe -> Processing-bots -> raw material -> fibrous, metallic, and concrete-like Assemblers -> various types of building blocks.
> It may even have shattered some of the gravel, meaning that stuff is really more like styrofoam. [...] All those stories of hollowing out an asteroid and turning it into a habitat or generation ship for 50,000 people aren’t looking so prescient. :)
Even simpler then, insert giant balloon in the middle, pump it up, cover walls with concerete and you have habitat, no expensive drilling and hollowing out.
What would you gain in that situation? Just some radiation shielding. Most stories about hollowing out asteroids wanted to gain at least some structural rigidity, which in your scenario comes entirely from the concrete you have to ship into space. Ideally you would want to melt the asteroid and blow it up to kilometers across and/or spin it for artificial gravity. Heating and melting foam is harder than solid rock or metal, and spinning it is useless if it has no strength in tension.
Structural rigidity in space is 99% tension and 1% compression, due to the lack of gravity, and I'm being generous to compression here. Rock is good at hold itself up against gravity, but is very poor at retaining an atmosphere compared to, say, UHMWP aka Dyneema.
Hollowing out an asteroid is more about raw materials and micrometeorite/particle shielding, both of which a slushy will provide in abundance.
In that case: blow up the balloon, melt rock outside balloon. You could make "cement" from grinding local material plus some binder, that way you bring in less mass. Radiation shielding is also a nice use for asteroid's mass. I'm just saying that blowing up a balloon is easier than extracting several cubic kilometers of rock from inside of asteroid. You can start from that premise and try to find some solutions.
> Heating and melting foam is harder than solid rock or metal
You can grind it, then blow it with very hot gas onto your baloon, making a nice melted coat of rocks. This technique is already used to repair metal rotor shafts, it deposits machinable metal: https://www.youtube.com/watch?v=NAeBpF84Q9M
Humans need room–temperature nitrogen, not nitrogen plasma. You would rapidly make the atmosphere inside your bubble unlivable. There are few easy solutions here.
Then you wait a moment until it cools down. Of course there are few easy solutions, space is very hard environment mercilessly waiting for you to make an error. You can find problems in every step. It doesn't mean you should give up before you start.
> All those stories of hollowing out an asteroid and turning it into a habitat or generation ship for 50,000 people aren’t looking so prescient.
If it's as loose as that then you could just put an inner steel "pressure" hull (the actual pressure from the outside would be negligible but it'd have to be able handle a human compatible air pressure) inside the asteroid and use the asteroid material as a radiation shield instead I guess.
Would work for a base but not for a ship with any appreciable thrust would shed material.
Worth noting that those "soft and fluffy" clumps of gravel and sand still move at 18+km per second and even one the size of Dimorphos striking the earth would easily cause an explosion big enough to completely level even the largest city (think 30 to 50 megatons of explosive energy upon impact). Or for example a comet, -mostly just a sort of dirty snowball- a couple miles in diameter would cause a global climatic catastrophe and vaporize every living thing and standing structure within hundreds of miles of its impact location.
Terrifying capabilities for such soft and fluffy, brittle things.
If they’re not possible then we’re going to have a lot of problems when we try to build rotating space stations for artificial gravity!
More seriously though, there is as always math for this. For an object to remain torus shaped it has to resist gravity trying to pull it into a more spherical shape around the centre of mass. More info here if your curious https://astronomy.stackexchange.com/q/2092/501
Unfortunately this technology is likely to be weaponized at some point in the future as radiation-free multi-megaton munition. The project name does tell us that the goal is to redirection not destruction of the asteroid.
This munition is very rare, has to be aimed a very long time before it can hit anything and the whole process is very noticeable. I wouldn't lose any sleep about that.
Counterpoint: it would, reciprocally, take months to launch a military strike to disable a military asteroid base, so it offers robust second-strike capability. You can no longer launch a sneak attack on your enemy's strategic bases.
The short timescale of nuclear war decision-making is chaotic, destabilizing, and has almost led to *accidental* apocalypse several times in the 20th century. Slow, deliberated deterrence could take uncertainty and accident out of the equation.
It's a good hypothesis that humanity developing asteroid deflection is more dangerous than not; that the optimal course is to do nothing.
(Fortunately, kinetic impactors like this project are borderline useless/harmless anyway (other than as basic research). Sagan was writing from the more ambitious worldview of the 20th century; a world where, if an asteroid is a problem, you cut a straight line through the problem with nuclear weapons. That's a more hazardous toolset!)
I think you might be overlooking the fact that it's simply a lot easier to redirect a big object than it is to completely destroy it. If the cheaper option does the job of keeping our planet safe, why would we try to go with an exponentially more expensive one?
This drives me nuts because 'affect' as a verb means something closer to causing an 'effect', while 'affect' as a noun doesn't. Because of that, on the surface, it feels like 'effect' as verb would make more sense than 'affect' when describing the action of causing an effect on something.
Anecdotally, I pronounce them the same way and have never heard anyone making much of a distinction (northeastern US), with the exception of the rarely used "to put on appearances" ("Dude, this intellectual affect is too much, stop it with the scarves!") which I'd generally put more of a distinct "a" sound at the front.
If it's so fundamental and obvious, then why wouldn't these world-class astroscientists say anything about any estimations of deviation after such surprising success?
Your toenail is affecting the asteroid's trajectory, by laws of physics. That adds nothing to this conversation.
They don't have a radar gun pointing at the asteroid which measures velocity. Instead, they have to measure position after a period of time to measure velocity. The smaller the change in velocity -- and this is a very tiny change -- the longer the time needed to measure the change.
There! That's what I was looking for. So they were expecting a miniscule change, and instead they were pleasantly surprised by the evidence and are now expecting a very tiny change?
It is a small value, but its a measurable fraction of the the velocity of its orbit around the primary (about 12h).
They know the momentum that the impacter had. They had an estimate of the mass of Didymoon and its velocity. They are interested in how much of that momentum was transfered to Didymoon and how much was carried away from ejecta.
I mean, they quote Ian Carnelli in the article, saying that he expects a "much bigger deflection than (he) had planned". That said, the article also mentions that it will take Earth-bound telescopes/radars at least a week to get initial estimates in regard to the change of the asteroid's orbit, and then three to four weeks before getting precise measurements.
I think the real takeaway here is just that something unexpected happen. They're monitoring as they would have regardless, and results will come in time. Expecting results and/or a conclusion this early is, well, jumping the gun.
You know, I have my doubts about the practical benefits of this whole operation given that there aren't any planet killers lurking in the asteroid belt for at least a century, and so I suspect this was sold with a planetary defense angle because a bit of a scare is a good way to loosen the pocket book. That said, maybe we could justify rebuilding Arecibo along similar lines. I believe they were in fact using it as a near Earth radar gun and it was even initially constructed as a defense project.
1. We have absolutely no certainty that no planet-killers are there. All we know is that none mapper are.
2. China has an Arecibo-class device. Actually bigger than Arecibo. Do we need two? Considering that the whole Free World could not scratch together enough money just to maintain Arecibo, building it again seems beyond possibility.
The astronomers I've seen lecture say that they have a pretty good mapping of the asteroid belt and they know that there are no planet killers in there anytime soon which seems to intuitively make sense since we only get planet killers on the order of every 100 million years or so. Of course there are tons of smaller asteroids out there that can be problematic as well. I wouldn't want to be around when Berringer Crater was created, but that was still a few 10's of thousands of years ago if I'm remembering right. (I'd recommend stopping by if you're ever in the American Southwest).
I'm not all that familiar with any of the big radio telescopes, but I thought that China's didn't have the active radar capabilities that Arecibo did. That said, I find it sad that something like Arecibo was possible to build and maintain in the 60's but not now. I suppose that has to do with the perception of it moving from defense project to science project.
There's a fair amount of chaos/uncertainty in orbital mechanics, so perfection may be impossible. Also, the smaller "city killers" can be very hard to spot, especially if they're in the wrong position relative to the sun, but those aren't extinction level.
That said, I would think runaway climate change or nuclear war are much greater threats to civilization (though humanity would probably survive in some form), so those are probably where the effort should go if survival of human civilization is your thing.
We have orbital predictions for all the asteroids above a certain size, but only a fraction of tens of thousands of smaller bodies entirely sufficient to end civilization and very possibly drive us to extinction.
One struck the ice sheet in Canada only 12,800 years ago that wiped out 30+ genera in North America including camels, horses, cheetahs, mammoths, mastodons, giant ground sloths, dire wolves, sabertooth cats, a giant beaver, and a giant bear. Their bones, and Clovis spear points, appear only below a thin stratum with massively elevated platinum concentration.
Radar is just a matter of putting the right antenna horn on the focal carriage, wired to appropriate gadgetry.
> On Sept. 26, DART crashed into Dimorphos at a speed of 6.6 kilometers (4.1 miles) per second. The impact should have changed Dimorphos' orbital period around Didymos from 11.9 to 11.8 hours — a difference of just 4.2 minutes. This will pull Dimorphos slightly closer to Didymos.
(Random aside, the sayings gospel Gospel of Thomas is attributed to Didymus Judas Thomas, effectively Twin Judas Twin, obviously such a twin that they named him that twice)
the kinetic energy of the probe was 900 times that of the gravitational binding energy of the moonlet, there is a non-trivial chance that the main thing we'll learn from this mission is how these gravel piles are destroyed via impactors. An important process to solar system development.
I think I worked it out that the kinetic energy is equivalent to around 2 tonnes of TNT, or of roughly a US Navy Atlanta class light cruiser doing 90 mph down the freeway.
> 900 times that of the gravitational binding energy of the moonlet
Wait, seriously? Maybe I should have paid more attention to the relative scale of these things. That makes it sound like the most reasonable expected outcome is total obliteration.
The mission was approved in 2015, which means it was designed before then, we've learned a good chunk about how smaller asteroids bind together since then, the hyabusa 2 and osiris rex missions were both after 2019, so it wasn't wholely unreasonable that some other kind of internal binding mechanism might be at play besides the piddling role gravity plays at these scales.
Yeah, like the other guy said about Firefox android, I normally use Firefox focus and I saw "0 ads". Maybe it'd because of pihole but I suppose focus does a good job by itself.
People need to forget using chrome on android at least
Sometimes these slightly-NSFW ads are what you get when you're heavy on ad blockers and such, because they're buying out the lowest/cheapest ad tiers where there isn't much targeting data available.
I'm definitely heavy on blockers and I didn't see any ad there (and basically anywhere else,) only the article text and pictures. I'm using Firefox and UBlock Origin on Android.
That's my point, though. The goal is to knock the asteroid off course sideways. (Perpendicular to its direction of travel, so that it misses the Earth.)
You slam something into it, and that changes the asteroid's momentum because total momentum is conserved in a collision.
If the asteroid stays in one piece, then after impact, it will be going sideways at some particular velocity. If instead some pieces break off and speed off at a greater sideways velocity, then the parts that didn't break off have to be going at a smaller sideways velocity.
In other words, if some debris breaks off, it carries away more than its "fair share" of momentum, and the remaining part gets less momentum.
We just need the target to change its orbit, in any direction, so that it misses the keyhole that will send it on a collision course with earth.
If we only spot an incoming asteroid on its final approach we are screwed no matter what we do.
DART is testing what we can do when we find a near earth asteroid that is going to pass near earth harmlessly but the "gravity assist", if you will, of this encounter with earth's gravity well sets it up to crash into us next time it comes around.
There is a specific volume of space (keyhole) that should the asteroid pass through it at the most unfortunate time (for us) it will hit earth during the next encounter. We just need to make sure it doesn't pass through that bit of space at that exact time. Knocking the rock sideways or slowing it down or even speeding it up are all valid strategies.
You may remember a while ago there was much concern about an asteroid named Apophis. When it was discovered, it's orbit wasn't so well understood and the error bars (more like error ellipse) included a keyhole that would set it on a collision course. Further study reduced the error somewhat but worryingly didn't rule out the keyhole, meaning that the odds of a hit started to appear more likely. Imagine something with 1/1000 chance of happening. Then you rule out 900 possibilities and end up with a 1/100 chance. This caused even more detailed study of its orbit to take place and the error was narrowed to the extent that the keyhole is ruled out entirely and now there is no concern Apophis will hit us in the foreseeable future.
I guess it's important because momentum is a vector, and the debris fly off in a direction on average opposite to where we anted to push it, so this also means that the momentum of the asteroid itself has been changed by (at least) that negative ? But why is this better than a perfectly inelastic impact without any debris ? Was a significant fraction of the asteroid blown away ?
You can apriximate the debris to rocket exhaust. There isn't an engine bell to direct it and make it all leave in the most efficient direction but it's still thrust.
> Astronomers rejoiced as NASA's Double Asteroid Redirection Test (DART) impactor slammed into its pyramid-sized, rugby ball-shaped target 11 million kilometres (6.8 million miles) from Earth on Monday night.
> Hubble images from 22 minutes, five hours and eight hours after impact show the expanding spray of matter from where DART hit.
> The Hera mission, which is scheduled to launch in October 2024 and arrive at the asteroid in 2026, had expected to survey a crater around 10 metres (33 feet) in diameter.
Nukes in space are actually not all that great. The same goes for explosions in general. A lot of our intuition for explosions come from how they interact with atmosphere, which will compress and expand, and mediate a shock wave in a way vacuum categorically does not.
A nuke is essentially reduced to a flash of ionizing radiation and a few kilograms of gas rapidly cooling and diffusing into the vacuum of space.
The variability of composition of asteroids, from rubble piles to solid masses, makes me think that future asteroid diversion missions will look not so much like a big gun fired at the last minute, and more like a decades-long programme of search, analysis, and engineering tailored to each target.
Wouldn't nuke going off just next to it nudge anything enough off course to not have to worry about composition? Or Hollywood yet again inserted a very unrealistic picture of how things work in my head.
Or we strictly prefer not sending nukes up there outside WWIII scenario. But then plenty of satellites have/had nuclear fuel as main source of energy, just not critical mass for anything BAM, just nasty dispersion in the upper atmosphere threat.
A nuke going off "near" anything in space will do very little damage - there's no shockwave propagation, so all you have is the bombs heat - which at least half gets wasted on empty space.
One of of the big problems with nuking asteroids is, as in this case, if it's a rubble pile then it can be considerably difficult to get enough physical contact with it to even meaningfully effect it.
Hence the reason for DART: we've got an impressive something but the question is did we even successfully deflect the trajectory of the bulk of the material?
Or, just fling a giant tarp or net (depending on whether it seems solid or not) at it and pull it in a different direction instead of essentially firing a projectile at it.
Thanks. But the animal analogy was heavy-handed and unnecessary.
The gist was, we've crashed into a single asteroid. There are zero conclusions we can draw from that sample size. So "a lot bigger" just means someone didn't consider the true range of possibilities.
Stop shooting sh!t at asteroids that are not heading for earth, please. You don't know upfront what's going to happen. What if the m0f0 splitted into two parts and one of the big parts was heading for earth now? Then what? Gonna play Armageddon, just as in the movies!?
There are more people on earth than only Americans, okay.
P.S. All jokes aside, all NASA people are probably very smart and sh!t, but please also think about all other people on earth. If you fvck up, you fvck up for everybody. Noblesse oblige. Space is pretty much unknown territory, be careful.
Yes, this is exactly why we are shooting shit at asteroids. So we do know what happens, so when that dark time comes and we need to shoot something at an asteroid to save a billion lives we know how to do it correctly.
And when I went looking for more information about DART it turns out they did. the LICIACube. very cool.
So now the question is why was this not mentioned in the nasa show(perhaps I missed it) and why have I not heard anything about LICIACube from anywhere else(perhaps I missed this as well).
did LICIACube fail and every one is being quiet about it?
https://en.wikipedia.org/wiki/Double_Asteroid_Redirection_Te...