Varda Capsule Reentry โ Five Minutes from LEO to Earth [video]
youtube.com
youtube.com
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
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.
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.
The gravitational potential energy of a 100kg payload in 100km orbit is 98 MJ. The kinetic energy of a 100kg payload in 100km orbit is 3042 MJ, over 30x more. So surviving reentry from orbit is orders of magnitude more difficult than surviving a straight up/down shot.
Now F9 boosters obviously have a horizontal velocity as well that they need to cancel out, but suborbital and orbital spacecrafts are very different beasts and it's absolutely noteworthy. It's the difference between surviving a car crash at 20 mph vs 95 mph. One is trivial, the other requires a heck of a lot of engineering.
E=K+U=GmM/2rโGmM/r=โGmME/r. We can see that the total energy is negative, with the same magnitude as the kinetic energy. For circular orbits, the magnitude of the kinetic energy is exactly one-half the magnitude of the potential energy.
Do the calculation over.
https://phys.libretexts.org/Bookshelves/University_Physics/U....
This is calculating the gravitational potential between two point masses. In other words, the potential energy if both masses were singular points at a distance from each other.
I was quoting the potential energy differential between being 100km over the ground, and on the ground. This is 98 MJ for a 100kg object, and that's what you have to cancel out to land back on Earth. The total gravitational energy of that object to the Earth's centre is more like 6300 MJ, but that's a meaningless number.
Dragon would qualify, except it lands on the ocean, so not "US soil".
agreed about dragon. those fuckers do orbit!
This is great because it does make it practical to recover the booster, but it's only possible by making the second stage significantly larger and more powerful than comparable rockets that stage later.
If the booster got up to orbital velocity, it would burn up just like the Rocket Lab "mothership" host satellite that accompanied the Varda capsule. They were coupled together, the mothership performed the braking burn to adjust their orbit into a reentry trajectory before the two separated. Only a minuscule amount of drift separated the two as they hit the atmosphere, but while the mothership burned up, the capsule survived.
If Falcon's booster achieved orbit, it would burn up just the same. The only reason it doesn't, is that it's only going a tiny fraction of orbital velocity when it comes home.
But what about Dragon?
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?
The incredible case of the disappearing polymorphs: https://en.wikipedia.org/wiki/Disappearing_polymorphs
It's an actual virulent molecule!
More seriously: this was pretty much solved already through improved techniques. I'm generally of the opinion that if you have to send a molecule to space to crystallize it better, you should probably spend your money on other, more terrestrial approaches. I do credit Varda for doing this automatically, rather than on ISS, because launch costs for autonomous vehicles are much more affordable than human space flight.
Ritonavir used as a drug works around the issue. It's produced as dispersed molten droplets inside a matrix of inactive material. Its heated above the melting temperature of ritonavir, so it prevents contamination.
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.
(Hope that never actually happens.)
https://en.wikibooks.org/wiki/Fundamentals_of_Transportation...
There's a gas heater on the market that works by using rapidly moving vanes to induce shock waves in the gas. The outflow has the nearly the same pressure as the inflow, but the gas has been heated, potentially to a temperature higher than could be achieved by resistive heating elements. EDIT: I mistated this; see below for link.
Consider also that once the shock heated air around the reentry vehicle has expanded back to ambient pressure, it will be hotter than it initially was.
Similar to re-entry heating: the specific kinetic energy of the returning capsule is many times greater than would be required to melt and vaporize any material. So why do things survive re-entry? Because most of the energy is dissipated in the bow shock, significant distance away from from the capsule, where air gets heated to temperatures higher than the surface of the sun when other air slams into it. The purpose of the heatshield is to protect from radiative heating from the bow shock, not convective heating. Ablative heatshields do not work because ablation consumes energy which removes heat (again, there is sufficient energy going around to ablate the entire craft), but because they place a shade (made of ablated carbon particles) between the bow shock and the craft, which shields it from the radiative heating.
In this case the entry regime was such that convective heating far outweighed radiative heating.
I mistated slightly: the gas is accelerated to supersonic speed then slowed in a diffuser, where shock waves heat it.
When the gases decompress they'll be a lot cooler, just like your AC.
https://ntrs.nasa.gov/api/citations/20140012475/downloads/20... (see slide 7)
I predict new reentry shaders being made for Kerbal Space Program by modders in short order.
Itโs basically ballistic downward, how do you make sure you wonโt hit anything on your way down over many layers?
Pretty neat the way it went from crazy hyperspace to a gentle, peaceful floating in the air!
You have: (G earthmass / earthradius)**.5
You want:
Definition: 7909.7861 m / s
also though the humans are animals, not stable configurations of plasma currents in the chromosphere or something
Those distances are arbitrary, and not specifically moored on the anchors of 0 and 100. Kelvin units are moored however on a fundamental anchor of zero heat energy, with arbitrary sized units above. It happens they were later calibrated to the Boltzmann constant, which itself is anchored on the triple point of water. None of this is based on human experience.
I must admit that, unlike a lot of HN'ers, I'm using a virtual keyboard on a heldheld device to type comments; I never took the effort of looking up how it is done though it must have to do with extended char sets.
i do most of my algebraic formulas with the compose key and a custom compose map mostly written by mark shoulson https://github.com/kragen/xcompose
for the above, after a false start picking random unicode characters, i realized that maybe i shouldn't use a modern language because someone who actually uses the language might feel like i was calling them an extraterrestrial, so i switched to googling archaic scripts. i pasted part of the old permic table from wikipedia
>>> s = '''๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ ๐โ
... U+1036x ๐ โ ๐กโ ๐ขโ ๐ฃโ ๐คโ ๐ฅโ ๐ฆโ ๐งโ ๐จโ ๐ฉโ ๐ชโ ๐ซโ ๐ฌโ ๐ญโ ๐ฎโ ๐ฏโ
... U+1037x ๐ฐโ ๐ฑโ ๐ฒโ ๐ณโ ๐ดโ ๐ตโ'''
>>> print(''.join(c for c in s if ord(c) >= 0x10350))
๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐ ๐ก๐ข๐ฃ๐ค๐ฅ๐ฆ๐ง๐จ๐ฉ๐ช๐ซ๐ฌ๐ญ๐ฎ๐ฏ๐ฐ๐ฑ๐ฒ๐ณ๐ด๐ต
>>> len(''.join(c for c in s if ord(c) >= 0x10350))
38
>>> permic = (''.join(c for c in s if ord(c) >= 0x10350))
>>> ''.join(random.choice(permic) for i in range(5))
'๐จ๐๐ฐ๐๐ '
>>> print(''.join(chr(i) for i in range(0x13000, 0x14000)))
๐๐๐๐๐๐
๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐๐ ๐ก๐ข๐ฃ๐ค๐ฅ๐ฆ๐ง๐จ๐ฉ๐ช๐ซ๐ฌ๐ญ...
๐ฟฆ๐ฟง๐ฟจ๐ฟฉ๐ฟช๐ฟซ๐ฟฌ๐ฟญ๐ฟฎ๐ฟฏ๐ฟฐ๐ฟฑ๐ฟฒ๐ฟณ๐ฟด๐ฟต๐ฟถ๐ฟท๐ฟธ๐ฟน๐ฟบ๐ฟป๐ฟผ๐ฟฝ๐ฟพ๐ฟฟ
>>> hiero = (''.join(chr(i) for i in range(0x13000, 0x13100)))
>>> ''.join(random.choice(hiero) for i in range(4))
'๐พ๐๐๐ฉ'
it's funny how this conversation has swung from the extreme of universal constants of the universe to the opposite extreme of completely arbitrary and historically contingent things like which ideograms (themselves completely arbitrary) are prevented from being posted by implementation bugs in hacker news
Thanks so much for this, let's see if copy paste works on this unix derived os. ๐๐๐๐ ๐ก๐ข๐ฃ๐ค๐ฅ
but sure, if it turns out that there are electron-degenerate-gas vortex intelligences on the surface of white-dwarf stars, they could very likely work out some way to launch robotic probes out of the star into places where water could exist, so that they could measure its triple point. and the folks on ๐จ๐๐ฐ๐๐ use trace amounts of water in their biology (it's a reasonably powerful base) and have isolated it in liquid form in their cryogenic laboratories. it's accessible in a way that the artifact kilogram and artifact meter and the circumference of the earth aren't
Which is a shame that the temperature scale is still anchored in that arbitrary mix, picked by a lazy apprentice. It's also historically base-10, not like the modern systematic base-8 units.
(Can ammonia actually alloy with methane? Their crystalline lattices don't seem to be compatible, and they don't react together.)
Metals can alloy with each other because the shared electron layer "glues" small imperfections in crystals where different metals meet. Can frozen ammonia behave similarly? Liquid ammonia can solvate free electrons, so perhaps frozen ammonia also can?
It'd be interesting to actually try experiments with frozen ammonia.
there are a lot of solvated ionic eutectics with atmospheric-pressure water ice, despite the absence of metallic bonding
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_...
That said I think meters and Kelvins are doing their job just fine even for use with rocket science. I'm glad I learned the SI units at school, they reduced the number of constants a lot in physical formulas.
i don't think it makes sense to describe miles or meters or stoney lengths as 'wrong' or 'right'; you can express the fitzgerald contraction or orbital speed or whatever equally well with any of the three, but one of them simplifies the fitzgerald contraction somewhat
agreeing on distances with a faraway colony is actually a considerably easier problem than the kilogram; if we transmit them a radio or laser message, they can measure its length to within parts per billion, and we can do that with 01950s technology, while kibble didn't invent the kibble balance (previously known as the watt balance) until the 01970s
(you do have to worry about redshift: one part per billion of redshift is 300 millimeters per second, so you have to know the relative velocity of alpha centauri to within meters per second to correct for itโand, while that's also the 01950s technology of measuring spectral line frequencies to that precision, that same technology is what allows you to do without the radio message entirely)
transmitting or storing the number "9192631770/299792458" can be done with significantly higher exactitude, of course, and can be done over twenty millennia more easily than transmitting a radio message can
Uhm, a kilometer is supposed to be 1/40000-th of the Earth's meridional (i.e. from South to North poles) circumference. The modern value is 40008km, so the official meter is juuuust about 0.02% shorter than it should be.
whether 0.02% sounds ridiculously good or ridiculously bad depends on your frame of reference
https://en.wikipedia.org/wiki/History_of_the_metre#History_o... says that the original mรจtre des archives in 01799 was machined to within 50ฮผm, which is 0.005%, four times smaller than the error in delambre and mรฉchain's computation. so even at the time that was a pretty large error. since then the measurement uncertainty of the meter has improved by five more orders of magnitude, to about 0.1 part per billion. 0.02% is 200 parts per million, or 200000 parts per billion, which is a lot more than 0.1
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'm pretty much a raw beginner with orbital dynamics but my vague idea was that you'd have to ellipticize the orbit by hundreds of kilometers to change the orbital speed by more than a fraction of a percent, and that would be expensive enough that you'd only do it if you had a really good reason
but the only satellites i've ever troubleshot had only extremely limited maneuverability (though i'm not totally sure how much more than that i can say)
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
> Nope, all audio was straight from the camera, no gain adjustment or muting. Something odd happened with the diaphragm in the mic I think.
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...
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.
Awesome video you created! Looks like there is bad weather over half of the planet though.
I didn't know what to ctrl+f to find my answer, settled with "sparks" and then "flashes".
Thereโs another cut earlier when still outside the atmosphere as well.
That sounds like an exciting day at work. ;-)
In this case, it wasn't really unscheduled.
To here (after reentry): https://x.com/VardaSpace/status/1760726397889466792?s=20
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.
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 larger it is, the longer it will stay hoovering and only slowly growing in size.
A city-sized asteroid wouldn't be more than a bright dot until the last seconds before entry, and at interstellar speeds it would take about three seconds to go from the vacuum of space to ground impact unless it had a very shallow vector.
also, seen by who/what? for the only known living things that could see it, it would be the last thing they did see. so maybe as far away as a couple of inches?
I love how they use this mechanic for storytelling in "The Expanse". The rebels of the belt threaten earth by slinging rocks at it at really high speed. Seems a very realistic way of interplanetary war. Why not bend some fast moving rocks to your enemy?
I decided to challenge the glorified-autocorrect machine with some more-manual napkin math, and I get 5.56ร10^13 megatons, which is smaller by a factor of ~786x.
That discrepancy is too big to explain just in terms of asteroid composition: Even an impactor of pure Osmium would only be ~12x more energetic.
Here's my work, if anyone wants to check for errors:
Asteroid volume 1 kmยณ
Asteroid density 1 2 grams / cmยณ https://en.wikipedia.org/wiki/Standard_asteroid_physical_characteristics
Volume conversion 1E+15 cmยณ / kmยณ
Asteroid density 2 2E+15 grams / km3
Asteroid mass 2E+15 grams
Asteroid velocity 0.9 c
Relativistic kinetic energy 2.33E+29 joules https://www.omnicalculator.com/physics/relativistic-ke
TNT energy 4.18E+03 joules/gram
TNT mass equivalent 1 5.56E+25 grams
Mass conversion 1.00E+12 grams per megaton
TNT mass equivalent 2 5.56E+13 megatonsHehe, I too love vacuuming.
Edit: added /s for those unable
I suppose you capitalise aspirin as well.
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.
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, 2ยฝ 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
I'm also talking about the LGM-118 Peacekeeper missile system. It was in service from 1986 to 2005. Did it ever needed to be used in anger or not? During that time did any military attack the nation which fielded it?
If not I would say it lived up to its name.
The US nuclear program is about deterrence after all. Well, after 1945, anyway.
These comments are being obtuse on purpose. Look at the name and look at what the name is on. The name peacekeeper is on a weapon that will only be used in times of no peace. Not a hard thing to see the irony in.
In my view, violence, or hopefully, just the threat of violence, maintains order.
There are certain classes of people where diplomacy and pacifism just isn't going to work.
Again, the post-1945 US nuclear program is about deterrence ("peace through superior firepower"). So, in that perspective, the Peacekeeper's threat of violence... kept the peace.
The US and the Soviet Union/Russia both do not want to use nuclear weapons.
Citation: Self. Was in the nuclear program during the latter days of the Cold War and shortly thereafter.
Which, you know, is the dice we're going to be rolling from now on. Maybe we'll survive the next century, then maybe the next, but in the long term? Humans just don't have that good judgement.
It is indeed a deadly weapon system. But it is used every second during peacetime too. Every second it is fielded it maintains a situation where the preferable choice of action is to not attack the one fielding it. In other words it is keeping the peace.
The name "peacekeeper" is a formal acknowledgement of its purpose in the military arsenal. It has no other role.
If you want peace, prepare for war.
Or as Roosevelt put it, speak softly and carry a big stick.
Building an incredibly powerful weapon and calling it "Peacekeeper" is meant to strongly imply that we don't plan on using it, but rather, it's symbolic as a preemptive threat against any would-be attackers. Peace is kept by showing that any attack would be retaliated with overwhelming force.
What else does maintain peace besides power?
The strong do what they can, the weak suffer what they must. If you want peace prepare for war. Do you think these are just famous slogans or they really do reflect some hard earned wisdom?
Would we still have an equivalent war deterrent today without nuclear? What would it look like?
My guess is something biological. My tongue-in-cheek guess would be something zoological (laser sharks anyone? pigeon pirahna hybrids?)
And in the short-term future, I think synthetic biology will represent an even greater threat than nuclear.
Why? Lethality, ease of manufacture once figured out, mishandling of process or materials, lack of regulation, ethnic/DNA targeting, etc.
Supposedly[2], they are sensitive enough that it's untenable to transport enough lead around to shield it.
1. https://en.wikipedia.org/wiki/National_Nuclear_Security_Admi...
2. I have no inside info.
What changed with nuclear is that you could maintain a credible and scalable strategic deterrent indefinitely at a tiny cost compared to maintaining conventional forces at an equivalent level of deterrence effect.
The only thing nuclear weapons seem to do is ensure their owners are always the aggressors in war and not defenders. Nobody wants to attack a country with nuclear weapons, so it enables them to pick and choose which wars to start.
But seriously these names are pretty much random, sometimes 'cool' sometimes not, just sequential NATO designations like Falcon, Felon, etc.
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
[1] https://news.ycombinator.com/item?id=36997821 [2] https://www.tomshardware.com/news/engineer-details-messy-lk-...
Very cool video though.