YouTube has shown people real big explosions (Beirut, Tianjin, etc) and how vicious they are, but you rarely see a CGI shock wave.
Rockets too, RPGs are fast but movies have them sauntering through the air.
The larger it is, the longer it will stay hoovering and only slowly growing in size.
however, that's because its trajectory was nearly horizontal rather than nearly vertical, so most of the people who saw it and were injured by it were tens of kilometers away, and it broke apart (exploded really) at 30 km up. it was initially traveling 19 km per second, 2½ times leo orbital speed. if you're traveling 19 km per second vertically instead of horizontally you only have 5 seconds from the von karman line (100km) until you make a crater or a tunguska
3 seconds from visibility to devastation still might be enough for hollywood dramatic flair
As a short-range interceptor, Sprints were slammed up out of their silos via an explosively-driven piston, then they would ignite and reorient in midair, accelerating at 100g to reach Mach 10. The missile itself couldn't see very much, but would be remotely guided with strong signals from the launch installation.
https://www.youtube.com/watch?v=gSFIkGfbLxs&t=23m37s
On a more scientific note, here's a video from the Space Shuttle boosters as they reenter (2005): https://youtu.be/527fb3-UZGo?t=70
So let's say your spies are telling you that the enemy can deliver 60 kiloton device with 200m circular error probable (CEP). Then your engineers can calculate how likely is that your bunker/silo will survive that (and can do something like a counter attack.)
And you build the number of silos you think you need based on that calculation. You put a lot of concrete and lot of work literally in the ground based on those numbers. And then suddenly your enemy just improves their guidance system and they drop (figuratively) such a video on you. That tends to cause jitters.
The US nuclear program is about deterrence after all. Well, after 1945, anyway.
You have: (G earthmass / earthradius)**.5
You want:
Definition: 7909.7861 m / s
You have: (G earthmass / earthradius)**.5
You want: mph
* 17693.688
/ 5.6517331e-05
You have: (G earthmass / earthradius)**.5
You want: furlongs / fortnight
* 47560632
/ 2.1025793e-08the original title said 'at 17000 mph', and as you can see, that's very significantly low, about 4%:
You have: (G earthmass / earthradius) ** .5 / 17000mph - 1
You want: %
* 4.0805157
i ask you, what the fuck kind of number is 9192631770? is that a hexadecimal encoding of linus torvalds's first child's birthdate? no, it's just a random fucking number derived from the sumerian base 60 numbering system and the average rotational speed of the earth in the 20th century. the kelvin has a similarly filthy history; it's when the thermal energy changes by 1.380649e-23 joules, because that makes the triple point of water come out to 273.16 kelvins. so now we have to preserve those numbers for all eternity like they're the fucking holy writ of the priestesses at delphi in order to interpret scientific papers from the 19th and 20th century. (and don't get me started on the motherfucking calendar. jesus jumping blue christ.)
you will be pleased to learn about https://en.wikipedia.org/wiki/Natural_units (which i used in https://dercuano.github.io/notes/2017-sap-allocation.html because i'm uncreative) and https://en.wikipedia.org/wiki/Duodecimal#Systematic_Dozenal_...
I'm assuming SpaceX doesn't count somehow? Boosters have landed on soil for sure (well, technically on landing pads), but maybe they didn't become spacecraft.
Falcon 9 is an orbital booster that's landed dozens of times on US soil. Suggesting this spacecraft has achieved some kind of world first is totally ridiculous and diminishes the actual achievement.
But what about Dragon?
For the true space nerds, here is the 27min uncut version. https://www.youtube.com/watch?v=BWxl921rMgM
also, congratulations. space is hard, and what you've done is harder than reentry
The heat is not from the friction, but from the compression of the gasses.
The implication is that the heating is like when one compresses air in a bicycle pump, the increase in temperature that comes from adiabatic (reversible, isentropic) compression of a gas. And some compression does occur, so there is some necessary heating from that source (as required by the second law).
But entry heating is not reversible. It's fundamentally irreversible, in fact. The gas is going through a shock. Shocks fundamentally cause an increase in entropy as fast gas slams into slow gas over a region whose thickness is on the order of a mean free path of molecules in the gas. And, in fact, the increase in density of gas going through a shock approaches a limit (around 4, IIRC, for air) regardless of the Mach number. So at sufficiently high speed most of the heating is coming from dissipation at the shock (a process akin to friction), over and above the heating implied by adiabatic compression.
And maybe the most worrying part is that there is more and more unidentified objects: https://sdup.esoc.esa.int/discosweb/statistics/
Also the number of payload really rised after 2020 (because of spaceX I guess).
1980: less than 1000 objects Today: Almost 10000 objects, including approx. 4000 in LEO only.
One dead giveaway is that they don't appear to be moving in perfectly straight lines. If they were distant, this would imply they were not free-falling but under powered flight, at an implausibly high acceleration.
You can see the same phenomenon in e.g. film footage of Apollo stage separation: https://youtu.be/9DNnZ82Kg3w
Amazing what is achievable with the tech of today. Space is not that far away after all. Still very odd to see the two scenes described above in a short video on YouTube.
Having the human walk towards the camera has a tremendous effect. It's something everyone can relate to and it puts a great context to all the scenes that are shown in the video before that.
What you said is still valid though, since the full video is not much longer.
Probably also helps that 17,000 mph is really freaking fast.
There's also a cut before the person appears, so it could have sat waiting much longer than a few minutes.
EDIT: As commenters noted, it fades out so it probably was edited in post.
also, sometimes audio amplifiers oscillate on their own (though i think the single-jfet preamp in an electret mic is unconditionally stable); an amplifier that oscillates in space in a way that physically vibrates the microphone might be damped by air so that you don't notice it when air is present
interestingly, microphone amplifiers oscillating and producing physical vibrations is not a phenomenon restricted to electronic systems: https://en.wikipedia.org/wiki/Otoacoustic_emission
pfdietz seems to be suggesting corona discharge encouraged by the lowered paschen voltage in low vacuum, and of course the negative-resistance characteristic of gas discharges can easily set up a parasitic relaxation oscillator; all you need is some parallel capacitance or series inductance, plus some kind of ballast that quenches the discharge http://tinyurl.com/23dt3d5e http://tinyurl.com/2de5uaog https://www.physics.purdue.edu/demos/display_page.php?item=6...
> Nope, all audio was straight from the camera, no gain adjustment or muting. Something odd happened with the diaphragm in the mic I think.
https://www.healio.com/news/infectious-disease/20240222/hiv-...
Is there a benefit to manufacturing drugs in low gravity environments, or is it more of an experiment to see if it's feasible, in a future where more people might be living in space?
https://en.wikipedia.org/wiki/Sun#Sunlight_and_neutrinos
> The Sun emits light across the visible spectrum, so its color is white, [...], when viewed from space or when the Sun is high in the sky.
> When the Sun is very low in the sky, atmospheric scattering renders the Sun yellow, red, orange, or magenta, and in rare occasions even green or blue.
> Despite its typical whiteness [...], some cultures mentally picture the Sun as yellow and some even red; the reasons for this are cultural and exact ones are the subject of debate.
The sun simply looks very different depending on where you are on earth.
Example (from experience/memory): the sun looks very orange/red during a Norwegian winter sunrise for like an hour or so.
Around the equator the sun is up and white within minutes.
There’s another cut earlier when still outside the atmosphere as well.
To here (after reentry): https://x.com/VardaSpace/status/1760726397889466792?s=20
That sounds like an exciting day at work. ;-)
They needed it.
So, while you should be careful including the sun in a photo from a camera, it really depends on the focal length and aperture of the lens used. Lenses with long focal lengths will create a larger sun image on the sensor leading to greater heating. The camera should automatically shrink the aperture when the sun appears in frame to adjust the brightness, but if it doesn't and the aperture is sufficiently large then you could end up with enough heating on the sensor to damage it. With a very wide-angle lens like the one used for this video, it's not likely to be a problem.
[1] https://news.ycombinator.com/item?id=36997821 [2] https://www.tomshardware.com/news/engineer-details-messy-lk-...
It’s basically ballistic downward, how do you make sure you won’t hit anything on your way down over many layers?
I didn't know what to ctrl+f to find my answer, settled with "sparks" and then "flashes".
Very cool video though.
I predict new reentry shaders being made for Kerbal Space Program by modders in short order.
Pretty neat the way it went from crazy hyperspace to a gentle, peaceful floating in the air!