For Questions That Don't Merit Their Own Thread

[K^2]

Just watched something break up on atmospheric entry off the coast of California at 2:46am Pacific, 10:46UTC. The flare and disintegration didn't look like a rock to me. Were we expecting a spacecraft re-entry? I can't think of anything that matches, but it really looked like something artificial coming back and fairly large, like an upper stage. Thoughts?

[NFUN]

A lot of traits in biology seem strongly conserved. For example, tetrapods have four main limbs, even if some are vestigial. And simpler clades like insects and arachnids preserved their leg count. How come over hundreds of millions of years hexapods are hexapodal, but their progenitor arthropods produced more variety?

[kerbiloid]

17 minutes ago, NFUN said:

arachnids preserved their leg count.

The solifugae have ten. And the arthropod limbs can be multifunctional, and even their jaws are limbs (while the vertebrates' jaws are former gills).

The centipedes even don't know, how many limbs they have, but every segment can be equipped with a pair of legs and even its own genitals.

The insects are the top of the arthropod evolution (the wasps and their descendants, bees and ants the top of the top), and they reached the optimum six legs, but their larvae like caterpillars in addition to their six may have several pairs of rudimentary false legs.
But anyway all of them have a set of minor limbs, and some of them can use them as additional legs.

[sevenperforce]

17 hours ago, K^2 said:

Just watched something break up on atmospheric entry off the coast of California at 2:46am Pacific, 10:46UTC. The flare and disintegration didn't look like a rock to me. Were we expecting a spacecraft re-entry? I can't think of anything that matches, but it really looked like something artificial coming back and fairly large, like an upper stage. Thoughts?

Looks like you witnessed the re-entry of a CZ-2D rocket body, the upper stage of the Long March rocket used to launch the Apstar 6E comsat to GTO back in late January.

[K^2]

4 hours ago, sevenperforce said:

Looks like you witnessed the re-entry of a CZ-2D rocket body, the upper stage of the Long March rocket used to launch the Apstar 6E comsat to GTO back in late January.

The page lists predicted re-entry on the 7th, and this was on the 9th. I'm not seeing anything on the list that's a better match, either.

I don't know if it's more likely that it was something that wasn't being tracked on this list or just a meteor that happened to look exactly like an upper stage re-entry. I mean, it was moving much slower than a meteor typically does, traversed enough of the sky before disintegrating to suggest a shallow angle (so the apparent speed should have been indicative of actual) and the track looked (entirely judged by eye) to be about 140°-150° heading, which is about right for a re-entry for a Russian/Chinese/ISS launch in a 50°+ inclination after you account for Earth's rotation. Plus, the way it flared up in a different hue after separating into several pieces suggest variation in composition very similar to what you see when interior tanks start burning on stage re-entry.

[sevenperforce]

5 hours ago, K^2 said:

The page lists predicted re-entry on the 7th, and this was on the 9th. I'm not seeing anything on the list that's a better match, either.

Oh, I got confused by the international date line. Yeah, I suppose that doesn't line up.

5 hours ago, K^2 said:

I don't know if it's more likely that it was something that wasn't being tracked on this list or just a meteor that happened to look exactly like an upper stage re-entry. I mean, it was moving much slower than a meteor typically does, traversed enough of the sky before disintegrating to suggest a shallow angle (so the apparent speed should have been indicative of actual) and the track looked (entirely judged by eye) to be about 140°-150° heading, which is about right for a re-entry for a Russian/Chinese/ISS launch in a 50°+ inclination after you account for Earth's rotation. Plus, the way it flared up in a different hue after separating into several pieces suggest variation in composition very similar to what you see when interior tanks start burning on stage re-entry.

Definitely sounds like space junk re-entry and not a meteor.

There are of course a bunch of Starlinks overhead at any given time but those failures are generally pretty closely tracked by AerospaceCorp so I doubt it was that.

Picking an arbitrary point off the coast of California and going to that specific time, I'm seeing a number of objects that could have been overflying on Heavens-Above, but they generally have very high apogees and perigees and thus would not have been expected to re-enter. That database won't show objects which are actively re-entering because objects low enough to cross the atmosphere at 3 am are going to be in the sun's shadow and won't show up in the search.

[sevenperforce]

Without getting into any of the political quagmires about these balloons that China keeps sending over to the US and that the US keeps shooting down...

There's indication that the balloons are able to navigate, hover over a single point, and so forth. How? Any ideas? Are they adjusting altitude to catch wind currents? Using some sort of ion thrust on the balloon surface to create thrust?

[magnemoe]

35 minutes ago, sevenperforce said:

Without getting into any of the political quagmires about these balloons that China keeps sending over to the US and that the US keeps shooting down...

There's indication that the balloons are able to navigate, hover over a single point, and so forth. How? Any ideas? Are they adjusting altitude to catch wind currents? Using some sort of ion thrust on the balloon surface to create thrust?

You have one option navigating an balloon, You can change your attitude, getting into more favorable winds. You can get around dropping lifting gas or ballast compressing lifting gas or air using power who these balloons might do but its still very limited. 
You can not hover unless no wind and you are limited to the direction of the wind.  You are not an sailboat so you have to following an wind. 

If you could make an solar powered drone who could operate over time as in compensating for no power during night it would work way better. 
But that is also something the US would want to grab, 

[K^2]

In theory, you can use power kites at different altitudes to generate net thrust in different directions, including against the wind. Think of a boat sailing against the wind, using a speed differential between the water and air, and the fin and the sail as two airfoils working in these two mediums. If you have different speeds or directions of wind at different altitudes, you can do exactly the same thing with kites.

However, I have never seen this put into practice, nor is there any indication of anything remotely like that on the photographs of these particular balloons. I think @magnemoe nailed it, that all they do is adjust altitude, and they simply have a much greater range to work with than conventional hot air balloons, which might give them a lot of options, depending on the weather. 

[sevenperforce]

1 hour ago, magnemoe said:

You have one option navigating an balloon, You can change your attitude, getting into more favorable winds. You can get around dropping lifting gas or ballast compressing lifting gas or air using power who these balloons might do but its still very limited. 

There was very clear reporting that the original balloon was specifically hovering over Montana. I think there was some suggestion that advanced, modern understanding and prediction of air currents could enable broad maneuverability for balloons simply by compressing or releasing lifting gas to change altitude.

I would love to see someone come up with a way to use ionocraft tech to “tack” against air currents, though. 

[JoeSchmuckatelli]

14 hours ago, sevenperforce said:

Without getting into any of the political quagmires about these balloons that China keeps sending over to the US and that the US keeps shooting down...

There's indication that the balloons are able to navigate, hover over a single point, and so forth. How? Any ideas? Are they adjusting altitude to catch wind currents? Using some sort of ion thrust on the balloon surface to create thrust?

As @magnemoewrites its the ability to change altitude to find favorable winds.

 

The difference between this and a 'weather balloon' is the combination of the ability to rapidly change altitude and loiter and the type of sensor array as well as the size of the package. 

It is evident just from the pictures that it's a spy balloon. 

It is also likely that the Chinese identified that the balloon was being observed and directed it to take some form of evasive action - this from some of the earliest reports. 

I will say this for the 'why didn't we shoot it down over Montana?' crowd: sometimes you want to observe a thing to learn about its capabilities and the user's interests. Also, bullets and parts falling from the sky onto a school or elder care center makes for bad press. 

[LHACK4142]

Why do so many photos of object recognition programs show bounding boxes:

instead of contours, which look much cooler?

[SunlitZelkova]

18 hours ago, sevenperforce said:

There was very clear reporting that the original balloon was specifically hovering over Montana. I think there was some suggestion that advanced, modern understanding and prediction of air currents could enable broad maneuverability for balloons simply by compressing or releasing lifting gas to change altitude.

I would love to see someone come up with a way to use ionocraft tech to “tack” against air currents, though. 

Hovering is certainly a euphemism. It probably actually flew in racetrack pattern over the state.

I suggest taking a hot air balloon ride if you are interested in how balloons can control their speed and direction.

[magnemoe]

50 minutes ago, LHACK4142 said:

Why do so many photos of object recognition programs show bounding boxes:

instead of contours, which look much cooler?

Simpler also don't have an hand against an black background but someone like the guy in center but with light blue pants and a green jacket. or as the second to left jacket overlap the guy in front. 
Instead you are tracking moving people, if they never move its probably an statue. 

[steve9728]

On 2/11/2023 at 7:36 AM, sevenperforce said:

Without getting into any of the political quagmires about these balloons that China keeps sending over to the US and that the US keeps shooting down...

There's indication that the balloons are able to navigate, hover over a single point, and so forth. How? Any ideas? Are they adjusting altitude to catch wind currents? Using some sort of ion thrust on the balloon surface to create thrust?

Because of my profession, I basically got into the habit of finding out about some research units and companies by looking for relevant papers: because Chinese science and technology talents really don't know how to sell their products or what they good at, they just know how to be exceptionally good at theoretical research. So, yep, I looked up the paper on "Stratospheric Airship Control and Design". Based on the seven to eight papers I've read so far, the current line of development for Chinese high-altitude balloons is to explore how to use them like satellite over a designated location. Such as in the "Study on Pseudolite Configuration Scheme Based on Near Space Airships (《基于临近空间飞艇定位的伪卫星布局研究》)" said that, "Compared to satellites and air vehicles, near-space airships offer very significant advantages in terms of cost, lag time, coverage area, responsiveness, flexibility, resolution and survivability." ... " Pseudo-satellites (in this paper referred to as near-space airships) can increase the availability, stability, reliability, and measurement accuracy of the entire system, and can even replace navigation satellites altogether when their signals cannot be received."" The basic requirement for a GNSS user is four visible satellites. When there are less than four visible satellites, the user cannot achieve navigation and positioning with the navigation satellites alone. At this point, the number of available satellites for the user can be increased by multiple near-space blimp seats" pseudo-satellites to meet the condition of at least four visible satellites, enabling a combination of blimp and navigation satellite navigation. Such combinations include '3+1' (three satellites + a ballon), '2+2' and '1+3'." The optimal layout of these airships is: "One airship is located directly above the reference station or positioning centre (with an altitude angle of 90°) at an altitude of 30km; the other three airships are evenly distributed over the perimeter of the service area with an altitude angle of 10° to 15°, the difference in azimuth between them is 120°, and the altitude is 20km, and the distance between the three airships is 86km according to the requirements of coverage area and minimum altitude angle."

And, "do they have any ability to control themselves?". The answer from those papers is "yes, but not pretty much". They are basically using the propeller power to maintain a range of corresponding positions within a tolerable range of airflow influences. 

Spoiler

From a paper named "Stratospheric airship control considering propeller dynamic model (《考虑螺旋桨动力学模型的临近空间飞艇控制》)"

Some of them used in airships that require particularly long dwell times - not in days and months, but in years - even have structural reinforcements on them. The atmosphere at high altitude is complex and the damn Murphy's Law - anything that can break will break - often results in a small percentage of balloons being subjected to the effects of the atmosphere at high altitude beyond what the control system on board can sustain, leading to the probability of the current "Hello, America".

Of course ,there's some weird answer for how to propel the airships themselves: in the paper "New Propulsion Method Study of Stratosphere Airship (《临近空间飞艇新型推进方式》)" shows that, they decided to learn from fish, or more precisely, the tuna:

There is even more than one shape for the tail:

Edited February 12, 2023 by steve9728

[JoeSchmuckatelli]

8 hours ago, steve9728 said:

decided to learn from fish,

I can see that from an aerodynamic perspective - but doubt it would be efficient as a propulsive mechanism. 

Interesting read, thanks! 

[K^2]

10 hours ago, JoeSchmuckatelli said:

but doubt it would be efficient as a propulsive mechanism.

If the Reynolds numbers are similar, I don't see why it shouldn't be. Of course, that would mean the technique is only efficient for a given size ranges at given altitude ranges. You'd also have to eat the complexity of the mechanism, which might or might not be worth it over conventional prop.

[Gargamel]

Working from the idiom that of a tree falls in the woods, and nobody is around to hear it, it might or might not make a noise. 
 

Therefore, the Anthropocene is Earth’s last geological eon.   Discuss. 

[kerbiloid]

https://www.reuters.com/world/us/us-officials-believe-flying-objects-over-alaska-canada-were-balloons-schumer-2023-02-12/

Check&mate, UFO unbelievers.

P.S.
Though, the "aliens" sound ambiguously.

P.P.S.
Looks like every second balloon is a blimp from Alpha Centauri.
So Kerbal...

[JoeSchmuckatelli]

4 hours ago, Gargamel said:

Working from the idiom that of a tree falls in the woods, and nobody is around to hear it, it might or might not make a noise. 
 

Therefore, the Anthropocene is Earth’s last geological eon.   Discuss. 

You did not specify human as the only 'body' and thus did not preclude a second sentient evolution.  Given that possibility, another observer could arise - after our demise - and discover a layer atop ours! 

[kerbiloid]

9 hours ago, Gargamel said:

Therefore, the Anthropocene is Earth’s last geological eon.

The organic film covering the Earth lithosphere will be dissipated long ago (+500 My) when the Earth matter gravitational differentiation will get finished (1 500 My) and active geology will be over.

In the middle, the biolife will get boiled, fried, and extinct, and long before that the humanity will get transformed into self-artificial biocyberpunk post-humanity and leave this planet to spread around.

Early Anthropocene
+0..100 y

Close to its final. < We are here

The evolution has produced the most effective and affective geological agent, the human species.
Being shaped as human units, the organic layer of the litho- and hydrosphere is actively self-reorganizing.

The naturally grown biosphere is in process of total recycling and replacement.

The natural wild species are getting extinct at exponentially increasig rate, especially the relict ones, which are living in debt (elephants, marsupials, wild predators, wild ungulates, many others) and occupy the room required for the human-compatible "domesticated" (actually, forcedly neotenic) species (cats, horses, dogs, cows, sheep, hens, etc.).

The geological landscape is directly affected by the humans in specific places (such as "mines", "fields", etc.)

This will finish with

• collapse of the natural biosphere and its total replacement with the manageable one
• collapse of the modern humanity model and the manageable population stabilized at nearly 2..3 bln (the "natural" capacity of the Earth, reached in early XX century)
• developed oceanic deuterium energetics
• almost closed megalopolis settlements with full waste recycling, requiring almost no additional resources to circulate, and thus dramatically reducing the mining and refining, and extracting trivial construction metals from any stone. Only precious lantanoid/platinoid/actinoid/light-element mining stays actual.

Late Anthropocene
< , +100 y .. 1 My

Humans dependency on the cybernetic augmentation is raising.
Genetic engineering makes the very term "species" obsolete. Wide experiments with reorganization of organic matter into custom biolife forms. No traditional animals/plants, a genetic form construction on demand.

Humans get organized into "communes" together with their local cybernetics and machinery. End of the known human society, human mind unification (based on their local biocybernetic bases).
Human body optimization, standartization. Absense of human competition due to absense of personal difference. A hive/commune self-identification.
Humans get equally perfect and optimized, everyone's mind is synchronized with their commune "Mother" AI. The humans became expendable units with standard personalities.
The mind stays individual, but everyone treats another one like another instance of their common "I".

The standard "I" is stored in the commune "Mother" computer and is "implanted" into every new human being as a default configuration, together with the basic knowledge base, compatible with the global "google".
Absense of the fear of death (rather than the desired personal immortality), as everyone knows that his living is required for the hive progress, and his/her private personality is just a default "I" with RAM experience to be uploaded to "Mother" AI to be used in the next instances of the commune standard "I".
Absense of a human life significance beyond the hive directives. Possibility of generation ships.
The "Mother" AI, though, is just an AI, so it has "knowledge", but doesn't have motivation, desires, fears. So it needs the free-will human units as symbionts both as flexible tools to interact with custom environment, and as will motors to set the weighting factors for its decisions.

0.1 c fast thermonuke Orions.
Generation ships spreading around at 10 ly distance. Colonization of the neighboring star systems (not planets), using planets as greenhouses and factories, but with orbital settlements.

Establishment of interstellar physical laboratory network, discovery of the unknown continnuum aspects allowing to create hyperspace jump portals, delivered by the said 0.1 c slow Orions.
Colonization of the close 500 ly bubble in the Galaxy co-rotational inter-arm safe zone.

Discovery of some physical effect allowing to form the counterpart portal remotely, by beaming energy into the portals nearby.
Possibility of trans-galactic jumps, colonization of the galaxy.
The non-human post-human beings (similar to the Babylon 5 First Ones) populate the neutron star proximities and start utilizing the isotope/particle/field cocktail and losing the interest for the planets,
The available planets get populated by artificial and adopted species for decorative purposes.

The Earth doesn't play a key role anymore, but is used due to its comfy climate and various mineral resources.

On getting uncomfy, the Earth gets abandoned.

Postanthropocene
+1 .. 500  My.

No time to appear for the wildborn sapient species, degradation of the artificial biosphere.

Irreversible heating by the Sun.
Slowing geological processes.

Mass exctinction of the biolife.

Postbiocene
+ 0.5 .. 6.5 Gy
Life is turned into CO2, Earth is New Venus.

In the middle (+1.5 G) the Earth matterfinishes its gravitational differentiation, the internal geological processes freeze. The Earth becomes a geologically stable (dead) planet.

Heliocene
+ 6.5 Gy
Sun makes puff.

Postheliocene.
Earth is either destroyed by the Sun, or stays in orbit as a piece of slag.

Maybe used by the post-human interstellar pulsar nomads to store loot.

Also, if the Sun is a white dwarf, the Earth of Slag can be a residence for the post-human creature, feeding from this white dwarf proximity junkyard matter.

Edited February 13, 2023 by kerbiloid

[darthgently]

1 minute ago, kerbiloid said:

The organic film covering the Earth lithosphere will be dissipated long ago (+500 My) when the Earth matter gravitational differentiation will get finished (1 500 My) and active geology will be over.

In the middle, the biolife will get boiled, fried, and extinct, and long before that the humanity will get transformed into self-artificial biocyberpunk post-humanity and leave this planet to spread around.

Early Anthropocene
+0..100 y

Close to its final. < We are here

The evolution has produced the most effective and affective geological agent, the human species.
Being shaped as human units, the organic layer of the litho- and hydrosphere is actively self-reorganizing.

The naturally grown biosphere is in process of total recycling and replacement.

The natural wild species are getting extinct at exponentially increasig rate, especially the relict ones, which are living in debt (elephants, marsupials, wild predators, wild ungulates, many others) and occupy the room required for the human-compatible "domesticated" (actually, forcedly neotenic) species (cats, horses, dogs, cows, sheep, hens, etc.).

The geological landscape is directly affected by the humans in specific places (such as "mines", "fields", etc.)

This will finish with

• collapse of the natural biosphere and its total replacement with the manageable one
• collapse of the modern humanity model and the manageable population stabilized at nearly 2..3 bln (the "natural" capacity of the Earth, reached in early XX century)
• developed oceanic deuterium energetics
• almost closed megalopolis settlements with full waste recycling, requiring almost no additional resources to circulate, and thus dramatically reducing the mining and refining, and extracting trivial construction metals from any stone. Only precious lantanoid/platinoid/actinoid/light-element mining stays actual.

Late Anthropocene
< , +100 y .. 1 My

Humans dependency on the cybernetic augmentation is raising.
Genetic engineering makes the very term "species" obsolete. Wide experiments with reorganization of organic matter into custom biolife forms. No traditional animals/plants, a genetic form construction on demand.

Humans get organized into "communes" together with their local cybernetics and machinery. End of the known human society, human mind unification (based on their local biocybernetic bases).
Human body optimization, standartization.
Humans get equally perfect and optiomized, everyones mind is synchronized with their commune "Mother" AI. The humans became expendable units with standard personalities.
The mind stays individual, but everyone treats another one like another instance of their common "I".

The standard "I" is stored in the commune "Mother" computer and is "implanted" into every new human being as a default configuration, together with the basic knowledge base, compatible with the global "google".
Absense of the fear of death, as everyone knows that his living is required for the hive progress. Absense of a human life significance beyond the hive directives.
The "Mother" AI, though, is just an AI, so it has "knowledge", but doesn't have motivation, desires, fears. So it needs the free-will human units as symbionts both as flexible tools to interact with the environment, and as will motors to set the weighting factors for its decisions.

0.1 c fast thermonuke Orions.
Generation ships spreading around at 10 ly distance. Colonization of the neighboring star systems (not planets), using planets as greenhouses and factories, but with orbital settlements.

Establishment of interstellar physical laboratory network, discovery of the unknown continnuum aspects allowing to create hyperspace jump portals, delivered by the said 0.1 c slow Orions.
Colonization of the close 500 ly bubble in the Galaxy co-rotational inter-arm safe zone.

Discovery of some physical effect allowing to form the counterpart portal distantly, by beaming into the portals here.
Possibility of trans-galactic jumps, colonization of the galaxy.
The non-human post-human beings (similar to the Babylon 5 First Ones) populate the neutron star proximities and start utilizing the isotope/particle/field cocktail,

The Earth doesn't play a key role anymore, but is used due to its comfy climate and various mineral resources.

On getting uncomfy, the Earth gets abandoned.

Postanthropocene
+1 .. 500  My.

No time to appear for the wildborn sapient species, degradation of the artificial biosphere.

Irreversible heating by the Sun, slowing geological processes.

Mass exctinction of the biolife.

Postbiocene
+ 1.5 .. 6.5 Gy
Life is turned into CO2, Earth is New Venus.

Heliocene
+ 6.5 Gy
Sun makes puff.

Postheliocene.
Earth is either destroyed by the Sun, or stays in orbit as a piece of slag.

I disagree with the presumption that humans can direct the preservation and evolution of life better than life can.

To paraphrase Thoreau, in wildness is the preservation of the world.  I would add to that a corollary, in freedom is the preservation of human purposes.

We cannot judge from our limited view what is "obsolete", but neither should we take obstinate positions on what isn't "obsolete".  We should be more willing to let things shake out on their own allowing what has worked to shape life successfully to continue to shape life balanced with the reality that we are a part of that process, both subject to it, and, at this point where terrestrial life is to seed other worlds, a bit more central to it.  But we are not the boss of it, we are stewards 

[steve9728]

7 hours ago, Gargamel said:

Therefore, the Anthropocene is Earth’s last geological eon.  

"You are not the first one, and won't be the last"

[Gargamel]

6 minutes ago, steve9728 said:

"You are not the first one, and won't be the last"

But what if we are the last?

[kerbiloid]

1 hour ago, Gargamel said:

But what if we are the last?

We are the best of the last.

The next last will be worse. Because we'll leave them no chance. They'll be dwellers of the post-human wasteland.

1 hour ago, darthgently said:

I disagree with the presumption that humans can direct the preservation and evolution of life better than life can.

Who said that we can better or worse? Who did ask us if we can? Who cares?

When you come to the forest, cut it, build a home, and start gardening, do you pretend that you are doing it better?
No, you just do it in your own manner, and the environment becomes human-compatible, is it worse or better for squirrels, wolves, or grasshoppers.

The cows and the dogs definitely think the human version is better. Who is disagreed and escapes, quickly gets explanations from the wild wolves.

1 hour ago, darthgently said:

We cannot judge from our limited view what is "obsolete"

The evolution doesn' care about someone's judgements, it follows circumstances.

What doesn't match the circumstances, has a greater chance to get extinct and thus obsolete.

To the moment, the marsupials (who are more primitive than placentalia) survive almost totally due to their isolation from more perfect creatures.
Once the cats, the dogs, the pigs, and the rabbits appear where they live, they quickly start explaining them who is obsolete and who is not. See the AU and NZ sanitation customs rules.

The elephants, giraffes, and rhinos still keep having their ecological niche, but the humans appear as a predator who has made their abnormally lasting existence unstable, and in a century their population will probably reach the limit where their genetical diversity will not sustain the reproductive ability of their species, whether it is good or not. The same about other RedBookers.
Once it happens, other species (probably, human-friendly ones) will fill their niche. When they have troubles, the human will assist them.

1 hour ago, darthgently said:

We should be more willing to let things shake out on their own

There is no "their own" in wild nature. Only eternal deadly competition with no happy end for anyone.

Every wild creature dies a scary and painful death, either being eaten alive (usually), or being broken in incident.

What humans do to the meat cattle by shocking them and then slicing the throat, is a fabulously merciful euthanasia, compared to the animal end in wild nature.

There is only violence in wild nature, only hardcore. "Humanism" is from "human".
The human is the only known species in the Universe who takes care about making its prey unconscious before dismembering it for eating.

Edited February 13, 2023 by kerbiloid