Ouatcheur t1_jauvidx wrote

Get off your dusty old books dating from before relativity explained Mercury's recession, and just put a bit more faith in actually fact checking reliable sources directly yourself?

Also, please get off your high horse. When you come with such an agressive attitude, the impetus is on you to prove your point, instead of just doing nothing more useful than throwing the cheap blow of an Ad Hominem without any extra substance to it than that.

That 18 km/s figure comes from the Lunar and Planetary Institute.

https://www.psi.edu/epo/ktimpact/ktimpact.html says :

Asteroids hit Earth typically at high speeds of 16 to 32 km/sec

Some move way faster and those are the really most dangerous ones. The 18 km/s is just some average, the reality is of course a spectrum.


That one is said to move "at warp speed" but it is moving at about "only" 6 km/hour. STILL at about twice the size of dimorphos it remains a super dangerous potential extinction event.

Still, the overall logic remains true within an order of magnitude for more or less similarly sized, similar speed asteroids.

Keep on laughing your ass off and judging others while actually contributing absolutely nothing that would be actually useful to the discussion. Congratulations!


Ouatcheur t1_jautk5r wrote

No I don't I never said or even implied it, it's you projecting something on me that just ain't there. I think you deeply misread me anbd my intent. Of course such an experiment is a vital one. But all media even NASA website definitely focus only on the half hour differential over the previous 11 hours orbit, and very hard to find data on the actual resulting delta V.

It is cherry picked information to make it seems as if it was a huge effect, but while it is indeed a huge accomplishment, in terms of actual delta V this is a tiny effect.

It is way too easy to just say "Go learn this!" in a condescending and dismissive way. While without correcting anything.

Well, I checked my numbers. Did you? I dare you to do the same computations yourself. And yeah when just trying to get a ball park figure, you are allowed to use simplified formulas, as long as they don't introduce "orders of magnitude" errors. No need to be a "scientist", kinetic energy formulas are simple.

And for tiny angles, sin (angle) is proportional to the angle.

Inverse proportional relationship: Mass <===> Resulting Delta V.

Inverse square proportional relationship: Speed <===> Kinetic energy ==> Resulting angle differential (for small angles) obtained from applying some force.

It's not rocket science. Orbital speed of dimorphos around it's primary is one thing, and it is super slow. Overall speed of a typical asteroid is over ten thousand times higher.

So with DART we got a resulting Delta V of 1 of a centimeter per second.

Over a year, that is approx less than 300 kilometers of deviation. This is only an order of magnitude value here as of couse orbital mechanics mean curved, not straight, trajectories. But the deviation remains a small one. The compounding effects won't magically stack up to somehow give superbly different total values for the final asteroid's position.

But here we want to deflect an asteroid so that it "misses Earth". This means we have to (at most) speed it up or slow it down or deviate it by approx 6500 kilometers (half the Earth's width). So you have to catch the asteroid really early on, or apply way more force than DART did, to succeed. Or preferably, both.

The media is all gloating about the "huge feat" without also talking about how you'd need scores and scores of DARTs to do the ACTUAL job of deviating an actual asteroid successfully, not just apply a super tiny actual delta V to it's orbital period. Something beyond our capabilities. "Just send a more massive DART that moves faster, and/or send a lot of DARTS", that means requiring a LOT more fuel.

We are still far from having a valid asteroid planetary shield defense. Very far. It doesn't take "top scientists" to see that, just checking the numbers at a very basic level and yet at a little bit more depth than just the surface evaluation of "Oh wow half an hour of an 11 orbit that is like about 1/20 of the job done!" when the ACTUAL job isn't changing a slow orbital speed by 1 centimeter per second, but changing a way faster collision vector speed by a whopping lot more.

DART is cool and all, but it fails to properly show how huge the task really is.


Ouatcheur t1_jalot2h wrote

Nope. The energy that is trsnsferred from the DART to the asteroid CANNOT be higher than the initial kinetic energy it has initially, no matter the way it penetrates the asteroids.

You don't get energy out of nothing!

But people often ignnore that the total enerrgy before must equal the totlal enerrgy after.

And before it is:


And after is is:

now-a-bit-saller-ASTEROID + its-EJECTA

People just tend to ignore the ejecta.

so in their minds it is

DART + ASTEROID(before) = ASTEROID(after)

or even worse it is:

DART + ASTEROID(before) + magicalwaytheimpacthappened = ASTEROID(after).

Like in "Oh it hit the dense core so it transferred MORE energy". Morer energy than what exactly? The DART fully crasthe asteroid, its, so it's gonna give 100% of it's kinetic energy no matter what. No "it transfers more than 100% because it hit something more solid". Duuh huuh huuh.

Sp, always remember the ejecta. And note that the ejecta is mostly ejected in the OTHER direction.

So the *only* way for the kinetic equations to balance out is for the asteroid to move faster once accounting for its ejecta (faster than if there hadn't been any ejecta at all).

The solidity of the "central" core part is irrelevant.

As the DART experiment proved, the amount of ejecta gives a MAJOR effect to the results.


Ouatcheur t1_jalmnj2 wrote

Moving fast doesn't screw radio signals up. Not unless you move at relativistic speeds in which case all it does is change the speed (the frequency and the data rate) of the signal. Not "jumble it out".

But 6 km/s while it sewsmc fast for us at ground level, it pitifullly slow when comparing to light speed. the relativistic Lorentz transformation effect aat such relative speeds is so tiny as to be completely ignorable.

And there is no atmosphere in space, either, so moving fast won't shake you around like a plane flying too fast beyond it's structural limits and being destroyed by air turbulences. There is no "wall of air" in front of you to constantly apply friction and slow you down: there is (next to) nothing! Basically, ideal conditions for moving around.

It is not the engine's power and speed that gives off that 6 km/s. It is the slow ACCUMULATION of speed by the engines. Forget Hollywood sci-fi when they nearly instantly reachh full speed when they lit the engines, then magicallly slow down to a stop when they turn the engines off. Things don't work like that in reality. At all. Think more like this: your spaceship has a speed vector. Each time unit, you move by that speed vector. It doesn't matter if you rotate where your ship is pointing at, it moves in the same direction of that vector. That is called inertia: things tend to keep on moving the same way unless a force is applied to them to counteract that. Now, you have engines, but all they do is, each time unit, add a TINY speed vector. Say, after accelerating for one hour, you are now moving 5 km/s from bottom to top. You could turn the ship sideways to turn to the "right" and lit your engines for say another hour. Then you'd be moving the same 5 km/s from bottom to top PLUS 5 km/s from left to right, thus now your speed vector is about 7.4 km/s going "top and right".

It takes a long time to accelerate something to 5 km/s. For comparison the fastest hypersonic jet known movves at Mach 6.72 = 4520 mph = just about 2 km/s. And that is with a jet with a superbly monstrous and HEAVY engine, that can use the abundant "thick" air it travels through as for it's oxygen for nburning it's fuel much hotter. Not the measly "built to work in space" engine of a little very fragile satellite. These two things can't even be compared.

Presumably, DART's propulsion systems were turned off for its very final segment, letting DART final closing in "sail through" mode, without any engines vibrations in other to get the best images. No atmosphere, means no vibrations and no friction. And very clear images, too. Once you turn the engines off, you just keep on moving inertially at the same speed.

From the point of view of DART, once itS' engines are off, it is immobile and it is Dimorphos that is closing towards it at 6 km/s. Not the other way around.

Because Special Relativity, ya know.


Ouatcheur t1_jall102 wrote

Orbit duration is a zilch-usefulness information.

What we need to know is by how much would an actual asteroid deflected (angle), and that is determine by the inverse square of it's speed.

i.e. an asteroid twice as masssive need a blast twice as big to be deflected by the same total angle. But an asteroid twice as fast, needs a blast FOUR TIMES as big. Kinetic Energy is proportional to square of speed after all.

I searched everywhere, found that pre-impact orbital velopcity was either 0.174 or 0.177 m/s. No word on the post-impact orbital velocity.

The about 11 hours orbit was lengthened by about half an hour. Supposedly, this means if you slowed down the thing by about 1/22 of it's pre-impact speed, then it's post impact speed would give just about that time interval for it's new post-impact orbit.

Going from 0.177 m/s to 0.167 m/s is a measly 1 *centimeter* per second speed vector change, in this case here a reduction, but it could be in any direction, really.

Also, found zero data on actual angular effects, too.

A real, typical asteroid moves at what, 18 km/s, average?

Does this mean that for this "planetary defense" thing to work, we'd have to scale it up by a factor of about 1 800 000 ? Just to get the same amount of angular deflection?

Good luck with that, I guess.

I think they focus only on giving the "whopping" 32 minutes orbital revolution slowdown change, because if they told the entire story clearly, that the dimorphos asteroid was deflected only by a measly 1 centimeter per second, then everybody would immediately see that this "solution" is laughably NEVER going to successfully "defend" us vs an actual asteroid coming for us.


Ouatcheur t1_j67kfec wrote

Except for a few of the prisoners that got filthy rich through their crimes.

In a country led by oligarchs and kleptocrats, where even the military is super corrupted from top military general all the way down to mere squad leaders, money always talks. As long as one can pay a sufficient amount of big bribes, he can walk away scott free and makec a *lot* of "behind the scenes" deals. Or be relatively treated ok (or even with favors) while remaining in prison.

This does't include those that were super duper filthy rich: those just bribed their entire sentence right away in the first place, and never went to prison.

But the "merely" criminally rich might have preferred to hang on to their illicit cash secretly, while remaining patient and in prison until they get out and then live well, because bribing their wait out prematurely would mean that once out they wouldn't be rich anymore. But now that "choice" has turned into either keeping your secret riches but going to the front and probably die, vs freedom and relative safety albeit not rich anymore.

But that probably applies only to a few. Most prisoners just would not have the money to make those kind of "deals".


Ouatcheur t1_j67jgwx wrote

I fully expect those that don't want to sign for the conscription to be "gently encouraged" to do so by the reputedly ever so fair annd amiable Russian police, military, and prison staff.

"No torture involved no sirrreree, never! They all jumped at the chance to defend the homeland, and all signed volontarily!"

(Said eery Russsian media spokesperson)


Ouatcheur t1_j67j34d wrote

I also love the usage of 'rapidly'.

Look closely at the photos, guys. That plot of cemetary is about the same size as only two normal houses properties. It's got 14x17 = 238 graves in it as of somewhere in the beginning of january, and 50 graves end of November. This is less than 200 dead in a bit over a full month. 7 dead per day is mere peanuts compared to how many really die at the front.

Those aren't all the Wagner soldiers, just a fraction.

Sure, those graves loolk real cheap: a colored drape with flowers, and a cheap wooden post and signboard with a bit of paint. But even then, given that they don't even give new "unwanted groups (prisoners, etchnic subgroups, etc.)" Russian soldiers much more than a couple days of training (if even that) plus a rusty old gun with only a few bullets, and no water no food no armor next to nothing, I don't expect Wagner to pay anything to put up nice looking graves for what they see as mere "cannon fodder". Those graves are for the "real" hardened Wagner boys that died, not for the fodder.

If all the dewad since the start of this stupid atrocious war were there, the graves would fill up (assuming a conservative 60000 dead --- not just specific Wagner loosses, though) then you'd need over 2400 of such cemetary plots. Take the *full* image, make it about 5 times wider and 5 times talller (i.e. 25 times that image), and that would be much closer that the minimum "real" size of Russian dead troops.

From Google Maps in Satellite View, that little plot is about 20 meters x 40 meters = 800 square meters, for about 250 graves. Let's be a tiny bit conservative and use only 3 square meters per grave. So for 60000 graves you'd need 180000 square meters, or a square cemetary about 425 meters on a side.

That's huge and the reality is probably even worse.

Fortunately for Poo-tin's army leaders, they don't have to pay much to bring back and bury all those dead, as they just leaves most of the dead right on the battlefield and pocket the money instead!

Typically in a war there are more wounded than dead, right? I'd be more interested in knowing where all the wounded are. Nobody in Russia seems to have seen tons of wounded soldiers brought back to Russia hospitals, so... Where are they all?

I suppose for Russia maybe there are next to no wounded: You're still alive? Well... the oligarchs already pocketed all the army's medical budget, ya know, o just plug that tampon in there to stop the bleeding, and just go back to fight! Even if you're three-quarter-dead, at the very least you should just go take another a bullet or two for our Glorious Mother Russia! Be hopeful: If you survive 6 months of this Hell on Earth total nightmare, you'll get a Lada.

(and the don't tell you thery fully expect to have to really give only about 200 Ladas, tops. Errr... only 50, really, because the corruppted military leaders will want to give some of those Ladas to their kids and friends).