Deep Space Radiation, Black Holes And Other Questions - Episode 14
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- Опубліковано 3 чер 2024
- Another round of off the cuff questions from my supporters at Patreon are answered, hopefully some in a manner which is useful and or educational.
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Can't believe Scott completely missed the most important advantage of space planes over capsules: They look so much cooler!
Any discussion of black holes and similar always reminds me of Terry Pratchett's observation that it's hard to discuss physics using a language designed to tell other monkeys where the ripe fruit is ;)
As always Pterry is strikingly accurate.
OOOOOOOOOOOOOK!
Ook
@Eric E he's not a Sci fi author mate. Fantasy 👍
@@stuart207 Eek - The “Long Earth” is most definitely Sci-Fi
My method for shielding is distance. I live on the East Coast and my radioactive in-laws on the West Coast.
I don't recommend it though, as no matter how far away they are their going to send me to an early grave.
That at least deserves a "LOL" ;~)
Damn you quantum tunnelling!
Lol. Bravo!
Hmm.
Multiply by the sqaure root of I-95, carry the Thanksgiving, factor back in the 4th of July...
Yep, the Theory of Relatives still applies.
_clears throat_ "in - (verse square) - laws"
A planet tidally locked to a neutron star with one side uninhabitable due to the radiation is hilarious to me as a concept.
"Here be dragons" indeed, the edges of the map would be absolute certain death
@@AsbestosMuffins would absolutely have to have some heavily shielded something on that side though, Just because you would need some way to involve that side in plot stuff. Just don't make it a prison, Space Alcatraz has been done a few times.
Read Larry Niven's The Integral Trees and Smoke Ring. They take place inside the stretched-out atmosphere of a gas giant that fell within the Roche limit of a Neutron Star. Fun reading.
I worked for an R&D firm where we used high neutron and high gamma ray sources to measure the density and porosity of material being drilled through in the oil and gas industry. Gamma rays were easy to deal with as lead would quickly absorb them. Neutron particles were much more difficult as they are at a much higher energy state. Hydrogen works well to slow, then stop the neutrons, but it takes a fair amount of volume. For portable shielding, we needed something better. We came with with a sandwich of UHMW and lead. The UHMW (1") would drop the neutron to a lower energy state, changing most of the radiation to gamma, alpha, beta, and zeta. A relatively thin layer of lead (1/4") could then absorb this EM radiation. We were able to make 2' square panels that could be easily moved by hand to be put into place to shield personnel from the radiation sources as they were being loaded into the tool and then sent down hole. This ment that the drilling crew was not required to have radiation monitor badges issued to them, nor were they forced off the rig while the quick installation of the sources happened. Two area monitors was all that was required. We never exceed 1mr/h at any time.
@@javaman4584 positrons maybe?
If you don’t mind my asking, what does UHMW stand for?
Let me guess, was this at Westinghouse research?
I am a nuclear engineer and have never heard of using concrete with lead in it. Since concrete is a structural material, they use iron instead. Usually in the form magnetite.
He's probably thinking of lead glass shielding.
Maybe lead shielding plates cast into concrete walls. I know some reactors had a lead shield surrounded by a concrete wall.
...and I am an retired space shuttle commander! 😎
I am your overseer then. It is: water. Good old water.
High Z-number elements to shield photons (X and gamma rays), low Z-number elements to shield neutrons.
Scott posts at bedtime. Ideal.
Yeah. I was surprised to see a post at almost 2 am lol
here afternoon!
Your Bedtime is the time I wake up
Bedtime? It's closer to dawn than sunset.
@@djbeezy it's only about midnight in San Francisco
For crewed missions to Jupiter's moons, there was the HOPE study, exactly for a mission to Callisto with numerous different variant depending on propulsion.
Was Callisto the moon with organic chemistry found in volcanic ejecta? If so, scuba astronauts would need to deal with local people,wildlife and microbes, just like on Europa (the moon).
@@johndododoe1411 I think it would be a pretty unlikely surprise to find local people over there.
@@johndododoe1411 that was enceladus
@@benbaselet2026 I used the term "people" loosely to refer to any local beings worthy of recognition.
@@forloop7713 Ah, then Callisto needs to be tested for signs of life before risking an astronaut mission (risks to all parties involved, Earthly or ET).
The following was an eye-opener for me. A substance is a good gamma ray absorber if it offers a high amount of _electrons_ per unit of volume, since it is ray-electron scattering events that dissipate the energy of the gamma rays. The substance Lead has a high density, but that is only _indirectly_ the reason why Lead is a good gamma ray absorber; having such a heavy nucleus means Lead has more _electrons_ per unit of volume than pretty much any other substance.
LATER EDIT:
As pointed out in the reply by Timmy Brolin: there are elements that are denser than Lead; significantly denser.
We know that lead is quite reactive, indicating that the outer electrons of Lead are relatively loosely bound. Generally, having loosely bound electrons tends to correlate with a larger atom size. As we know, Gold is highly inert. I assume that is because all the outer electrons of Gold are _tightly bound_ , which tends to correlate with smaller atom size.
Gold and tungsten are almost twice as dense as lead.
Waitwaitwait. Does that mean a concentrated solvated electron solution might be an excellent radiation shield??
@@MomemtumMori Not a physicist, but probably not. Solvated electron solutions are usually electrons solvated in ammonia, so you get 1 electron surrounded by several ammonia molecules, and ammonia has the very light elements (compared to lead and gold) hydrogen and nitrogen which have few electrons compared to heavier elements. Plus it would be a liquid which is less dense than a solid.
Compared to this, any heavy metal has much more electrons per unit volume.
Lead has the advantage of being inexpensive compared to tungsten and gold and much more easily workable than tungsten.
Does this mean that giving the ship's exterior a negative charge could be helpful? Could "polarize the hull plating" be a real thing?
The difference between radiation requirements for LEO vs GEO (and above) is night and day. A LEO capable FPGA is $5, a GEO capable FPGA is $15,000. Redundancy means nothing if the part latches up and burns out.
Neutron stars can also go flying on exciting trips through the universe as a result of the dynamics of their birth. That presents the possibility of a neutron star being an extrasolar capture or even temporary visitor.
They’re also very hot, so radiating xrays. Though from a small surface area.
1:20 on Earth we use both: heavy materials such as lead and even depleted uranium for gamma absorption, and light (high hydrogen, such as water, paraffins or polyethylene) materials for neutron shielding.
When the radiation is mixed, a layered cake approach is used, called graded Z shielding, where the materials with an increasing atomic weight are stacked in proper order
Meaning the highest atomic weight i.e. U or Pb on the farthest exterior? Makes sense. Like an eggshell.
@@joeltashinian5888 the neutron shielding (Low Z, light materials, water or hydrocarbons to slow neutrons and usually boron to absorb them) goes on the source side, and then the gamma shielding (High Z, your lead or whatever) on the safe side. The idea is that neutron capture emits a gamma and so you in turn shield from that.
@ScottF short answer: yes, everything falling in is imprinted on the horizon, from an outside perspective. It not only gets redshifted to invisibility but also roasted to a plasma soup in the accretion disk, so the imprint is massively scrambled. Finally, of you were to fall in you actually could witness the event horizon and you would reach the singularity in a finite time. PBS spacetime covers all this in detail if you want to know more.
Oh, shorta like I thought.
They object gets "grinded" into oblivion with part of the energy falling into the singularity and the other part turns into a very bright source of radiation.
@@youkofoxy Yes, a BH can actually starve itself by eating too fast. The enormous radiation can blow away its food.
@@cmilkau LOL, I love how we tend to anthropomorphize everything. ;)
Right... A big part of this is remembering what 'seeing' is. In order to see an object 'stuck' at the event horizon, you have to be bouncing light off it, and that light has to escape from the black hole to reach your eye (or detector). Even if there's a pathway to allow the light to reach you, it'll redshift so far that it'll only be detectable to a radio telescope. Is the object 'detectable' at that point? I mean like... maybe? But it'll be spaghettified and plasmarized to the point that it's just a cloud of particles anyway. Wouldn't be much there to detect.
@@Keenath I feel like this bit is so often missed too. The easy answer is no, you can't see an object if that object's light can't reach you, but people get hung up trying to express what the object itself may be "experiencing", which is irrelevant even in this context as the object isn't experiencing the same time dilation as we'd see from the outside...
Paraffin is an excellent hydrogen rich absorber seldom mentioned. It has material advantages like castability or block walls and no toxicity.
What about its other excellent property of flammability?
@@thatguy7595 That would need oxygen though. And heat sufficient to liquify or vapourise it. Given that you are in a spacecraft which also stores hydrogen or methane, if you get to that point then you have bigger problems. I think the original poster may be referring to paraffin wax rather than paraffin? I belive in the US, paraffin usually refers to the wax, in the UK etc it refers to the liquid fuel (kerosene).
@@thatguy7595 How could an outer shield made of wax blocks ignite ... in space? ... you know there's a vacuum? ... that means NO oxygen!
Careful, when you say paraffin to a Scotsman he hears "kerosene." (That's what paraffin means in the U.K.)
What is the British word for "paraffin" wax?
It's funny when certain people pretend space and especially the Van Allan belts are some sort of insta death nuclear reactor they have to fly through. Because, you know, "Radiation"...
Also thumbs up for having "Universe building" as hobby.
It goes both ways: There are the ones thinking that a tiny little bit of radiation will kill you and the ones who pretend that bathing in radiation, at best for a long time, has only beneficial consequences for your health... I am always baffled by their lack of scientific knowledge and how they can at the same time be so confident.
Humans today are morons. Between the Google effect and Hollywood movies most people are incapable of critical thinking. Nuclear fission could replace fossil fuels easily, but the public has been so brainwashed they think it's more dangerous.
@@JessiBear It is the same as with planes - they don't fail nearly as often so they are safer, but when they do fail, it is a big thing.
@@JessiBear humans have always been morons who did stupid things despite knowing better. Only we know more so much more things are perhaps stupid with no excuse.
@@JessiBear Well, because nuclear fission _is_ more dangerouse
There only has to be one incident to kill many, many thousand people and cause cancer in uncountably many more
The greatest amazement of space is this:
How easily it can turn great minds into nothing more then confused children.
Well done black holes, may we never fully understand you!
"If you wanted to mount a mission to Callisto, it wouldn't be to hard. " - Scott Manley, January, 2022
Hmm. Ultra high density polyethylene is pretty tough stuff, used for body armor panels & such. I’ve no idea how hard it would be to manufacture in the appropriate sizes, but maybe it could be used as a structural skin for at least parts of the crew areas on interplanetary ships. It would probably make decent micro-meteor protection too.
One thing I always wondered, why not shield the sleeping bags? Lead lined sleeping bags, plastics for cabin shielding etc... You don't wear it all day but but it could cut a nice chunk out of the daily exposure.
Because a lead lined sleeping bag would make radiation from cosmic ray exposure worse, but it would make Gamma and neutron exposure better.
12:50
Short answer should be: Yes, except that things get atomized and redishifted to the maximum, so they can't be seen.
But otherwise (ignoring a couple of physical effects) they would indeed appear as frozen images on the back hole's surface.
So they would emit photons forever... something doesn't add up...
Thankyou for more question's scott! Really love this series. Greetings from Australia
From the vantage point of a distant outside observer, an object falling towards a BH and very near the event horizon would not only be gravitationally redshifted and frozen in time but also smeared and scrambled over the whole surface of the event horizon.
On the Fairing question, the two main factors in size/shape fairing changes is Center of Mass (CG) shifts AND Center of Pressure (CP) shifts, or as we call in Rocketry, CG over CP. Center of Pressure has to do with the air drag/air flow over the total body of the rocket, including any fins, etc. and what stability factor there is left. Yes, there is steering capability on most rocket motors to not only direct the flight path but, just as is important, stabilize any wobble in the rocket going through the atmosphere (wind loads, boundary flow turbulence, etc) and as you get closer to a CG(mass), Center of Pressure adjacency, the rocket becomes more unstable, beyond the corrections of the motor gimbaling. One curious thing is why there is no layman curiosity question on why the Saturn series of rockets had first stage fins and subsequent commercial rockets do not but again, as a five decade Rocketeer, I know from experience! :-).
Of course the very first Saturns had no fins, as there was sufficient control authority from the engines. FIns for Saturns came along once additional stability margin was desired in case the abort system activated on a crewed flight. They would then buy more time for the abort system to activate and function.
Another thing about Space-plane vs capsule is thermal management of the spacecraft; because space-plane has a longer reentry time (a lower G-load) than a capsule then it soak up heat more than a capsule and therefore the thermal management system of a space-plane is much more complex than a capsule, whereas a capsule can rely on its thermal mass to buffer heat intake (and therefore only need a simple wood/plastic-resin ablative heat shield) a space-plane require a more advance non-ablative heat shield with a very efficient thermal insulation ability (eg: aerogel) or a sweating skin/evaporative/transpiration cooling ability (yet to be developed or demonstrated in public domain, perhaps already exist in hypersonic vehicle?).
Well, lower and longer heat loads are disadvantageous for expendable heatshields like ablatives, but advantageous for radiative reusable heatshields like ceramic ones.
Dr Robert Forward wrote a great story titled “Dragon’s Egg” describing life on a neutron star and how humans could contact them.
It was one of the most surprising and enjoyable examples of worldbuilding I’ve seen in SF.
_@Richard Anderson_
I´ve heard of but not read this sci-fi author; however, a _doctor_ of physics trying to rationalize beings living on a surface with a _million_ Gs of gravitational attraction!?
I´m dubious by default.
@@brianhiles8164 All I can say is, “Read it.” All will be explained. I had the pleasure of meeting Dr Forward. Definitely not your typical Physics professor.
@@noeoep Going out on a limb but I'm guessing the life on the star is made of neutronium, or w/e ultra dense matter they called it, and arose under an evolutionary process just using intensely dense matter and massive heat
Hal Clemet did one called 'a Matter of Gravity ' also a story about life on a neutron star. Most of his books were world biulding and life on those worlds.
The best space related channel out there. There.are so many channels but many alas say too much superficial stuff with no deep insight. But I guess every level of analysis has its audience. Here is the place for the more in depth kind of viewer lol
dude, Anton Petrov, check him out. he and Scott are very similar, Anton mostly explains new papers AND he uploads daily.
@@viestursgfl6178 Yed you are right I am subscribed to his channel. You are right I forgot him. I was thinking about those who use catch phrases like click bait etc.
Scott is exactly the perfect middleman between the "hard science" side of things and the "space is cool" discourse. For someone who doesn't need to understand the maths of it all, but wants to be in the know about what goes on in space research and technology, he's a truly fantastic resource.
PBS Space Time has in depth stuff and usually tackle Black Hole phenomenons without fussing around.
Another good channel is Sabine Hossenfelder, also no fuss, but not focused on space alone but rather physics and what else is on.
Both those channels are being moderated by publishing phD physicists with teams behind them, so should meet the high levels you set.
Anton Petrov though don’t do my guy dirty
Rule of thumb with radiation is: Time, distance and shielding. So in outer space you are surrounded by radiation all the time. You can not limit you exposure nor put some distance between you and the source so all you have let is shielding.
Take a MIG-29 tourism ride to 70,000 ft then pull the ejector seat to get an extra boost!
I want to mention that radiation hazards in space are in general vastly overestimated by laymen. I mean sure, radiation hazards are serious and we need to adress it for certain missions in the future, but I have had people in discussions who were 1000% convinced that 90% of people going to Mars would die of cancer before they got there which is of course ridiculously incorrect.
For missions to the moon you would easily get away with not shielding anything at all if you wanted to.
That last little remark is a bit perplexing. No shielding at all? Through space and to spend 6 to 12 months on the moon unshielded? Then a return trip and no I'll effects to your equipment or health? That's surprising.
@@x--. The best data for the radiation hazards on the moon might be the data of the German and Chinese science team that analyzed data from China's Chang'E 4 lander mission from the far side of the moon, which resulted in measured 1,369 microsieverts per day. I don't want to sugarcoat it thats still very relevant and nothing to ignore. But for a 6-month mission this would result in comparably managable 250mSv.
The Multilateral Medical Operations Panel, which coordinates medical system support for the International Space Station, set a 30 day exposure limit of 250 mSv, an annual limit of 500 mSv and a career limit of 1 Sv.
This means an entire year on the moon should, very closely, still be within this annual limit of 500mSv.
As a result it would be theoretically in line with the exposure limits set by the MMOP to have a 2-year mission to the moon for astronauts once within their career as their only visit in space.
Exposure to a dose of 1Sv, which would be the result of such a 2-year stay, is associated with a five percent increase in fatal cancer risk in science.
This is of course something you want to establish solutions for.
But its not as life threatening as one might think.
@@x--. he didn't mention any time frame, so he might have just meant an Apollo-style flags and footprints mission
Scott, great stuff as always and thanks for taking my question on black holes. I’ve been looking for that answer for about a year now but couldn’t find anything that wasn’t spelled in a physics equation. In retrospect, I guess I had the time to study the subject and figure it out….I digress. Thank you and thanks to your commenting fans for the enlightenment.
19:59 "the propellent would slosh against the side of the tank and keep it cool"
Are they not pretty well insulated given that they have to withstand direct sunlight for months?
Anyway, if you use crygenic liquid fuel to cool the ship then that fuel has to absorb the heat. A shield radiates it to the atmosphere, the fule will just get hot. getting hot means the fuel will expand. If you don't want your ship to explode then you're going to have to release the overpressure and that means venting fuel and *pure oxygen* into the space around your craft at the very moment that things are getting to temperatures that are already enough to melt the skin of that craft. The fuel release would probably be a nice flame but the oxygen will happily burn anything; the nozzle, the pipe leading up to the nozzle, and once the hole is big enough; the ship. keeping the fuel and oxygen away from heat is probably priority number one.
On the subject of heat; it'd be interesting to hear how SpaceX are planning to deal with heat in their craft given that the designs have not shown any external radiators... or solar panels.. or anything really...
Scott, Thanks for the laugh when you broke your brain on a black hole.
I wish I had subtitles so people would understand when I'm talking through my hat.
Instead of using magnetic fields to steer ionized particles, is it possible to create shields comprised of ions traveling in loops? Essentially ion thrusters and stellarators that knock incoming particles out of the way with flows instead of fields
The nice thing about focusing your efforts on solar radiation is that you only have to worry about whatever portion of your spacecraft is facing the sun. A cylindrical craft, with its engines and fuel tanks and assorted mechanicals down at the "sunny end" of the ship, wouldn't need a huge amount of extra shielding to protect the crew up at the other end.
HI Scott, Active radiation shielding was my actual thesis idea on MSc, But it was in 2019 and I learned someone else came up with the idea first. Still very interested in the tech. Thanks for the video! Orbit safe!
A black hole 's a fantastic creation
Whose physics defy explanation
Time and space they so bend
Such that few comprehend
The gravity of the situation
Poetry of Motion
It was my understanding that water is a great shield against Cosmic radiation. Wouldn't it more feasible to simply store your water in the hull of the space craft on long duration trips? This would lessen the added weight from additional shielding 🤔
Just keep your fuel tanks between the astronauts and the sun: oxygen and methane do pretty god stopping most of the particulate radiation. The highly-penetrating stuff doesn't interact much with tissue.
That is indeed a proposed design for long-term in-space use, placing water or fuel tanks on the outside of the craft.
@@paullangford8179 presumably your fuel tanks would be mostly empty by that point
Water has added functions: for drinking and growing crops. Thermal mass and thermal distribution, like EVA suits’ heating/cooling systems on steroids. In a pinch it can be electrolysed for rocket fuel or left alone as reaction mass in a steam rocket.
I need 100% neutrino block. Does that come in an spf?
Hi, Scott. I was interested in the black hole question. It is easy to confuse the information about the falling object with the object itself. There are probably quantum values involved, but the object's mass doesn't seem to be an electromagnetic effect. So the object will fall past 1C, passing C at the event horizon. All the quarks in the electromagnetic domain will be unable to maintain cohesion, disassembling into their quakian sub-particles. Some of them may get swept up by the electromagnetic field and accelerated along with the charged quarks into the galactic jet. The energy released by the fission of the quarks must be millions of orders of magnitude greater than that released by the fission of the atoms as they fission into quarks. The gravity field at the event horizon is 1C. But the gravity at the center of the black hole must be proportionately greater than C. If the quarks in the gravitational domain had been destroyed then there would not be such a high gravitational field in the first place. So something with gravity accumulates at the center of the BH. At the center of the black hole, there should a quarkian crystal analogous to an ordinary neutron star. Also, a consideration is the momentum of the structure. At the event horizon, the speed of orbits is also C. The mass of objects is falling into the BH, so their momentum is added to the rotational momentum of the BH. Maybe the actual object at the center of the black hole is a disk or donut shape. It should be rotating faster than light speed. What a sci-fi environment. I wonder what time and space exist there? Maybe at some point, there is neither time nor space. Thanks for sharing! Stay Healthy!
An object falling into a black hole would be as you say massively red shifted, but also the number of photons escaping would reduce as it falls so it would become much much dimmer - so seeing any object falling into a black hole just becomes harder and harder to see, until you are detecting individual massively red shifted very sparse individual photons
Fairings: I wonder if the JWST program would have cost less if they had decided to spend the money to develop an enlarged fairing for Ariane 5, rather than all the mechanisms to fold the mirror and such. I know that the thermal blankets and instrument systems were a major deal, but maybe some of it would have been simpler if an oversized (7m?) hammerhead fairing had been developed, even as a one-off.
I think that some of the reasoning for the folding mirrors was to allow them to adjust the focus to address manufacturing flaws, since the JWST is too far away for a practical service mission like the one that was performed on the Hubble Space Telescope.
The JWST is massive. A plus-sized fairing might have made things a little easier, but there still would have been a lot of origami required. Plus, even if payload volume wasn’t an issue, I think a lot of the JWST just isn’t able to handle launch forces in the deployed state. Can you imagine that multi-layered sun shield or the secondary mirror arm in that situation?
16:36 Ok, it must be my Trekkie mind taking over but that has NCC-1701 all over it.
One interesting bit I remember about radiation on Europa is that it differs drastically on the prograde and retrograde hemispheres. Because it orbits slower than Jupiter rotates, the particles trapped in the Jovian magnetosphere slam into its retrograde hemisphere, while the prograde hemisphere gets shielded somewhat.
And luckily, since it's tidally locked, anything you build in the prograde hemisphere will stay in that shielded area for the foreseeable future!
Its refreshing to see more than 10 minutes of actual knowledge from this channel nowadays!!
Damn Scott unlike most youtubers your content gets better and better wich is super refreshing
Can we all appreciate the fact that Scott never disappoints us with his content 👍
In this one he does spread bullshit.
No. That is forbidden.
18:35 I think you meant there are advantages to space planes.
certainly, if Sierra Space has there way, there will be a manned Dream Chaser before too long. It is very unfortunate that we have lost Skylon, but I think that spaceplanes vs vertical landers, of various sorts, will be a market competition that will spend the next several decades working itself out.
Scott regarding radiation protection (a topic I worked with), if the issue is protecting vs neutrons then Aluminum is a bad idea as neutrons + AL produce a lot of radio active (gamma) isotopes - some quite long lasting (many hours). Hence on earth protection is metres of concrete and doors consisting of a hydrogen rich core (eg borated paraffin in a wood frame typically 15-20 cm thick and then both sides covered by high boron steel a few mm thick - the steel being needed to stop any high energy gamma rays generated as the neutrons bounce around inside the door while slowing down.
Decades ago I visited an experimental neutron radiotherapy unit and was impressed at how every thing inside the treatment room was made of either wood or plastics or steel but absolutely no Aluminum anywhere.
Scott Manley back at it again with the best shirts
Nowadays I prefer "string theory" explanation of black holes.
All mass is contained on the "event horizon". So there's no infinite density problem nor singularity issue.
A black hole is in essence a HUGE "particle" that consists of many (and I mean MANY) particles that fell into it.
Hawking's radiation is also much easily understood once we take ST into the account.
5:25 for those interested, those exposure levels are per day. You start to get determinstice, acute radation syndrone right at about the 1-2 gy/sv range, so right in that first hour, you are already in trouble for Io, after about the 4rd or 5th, you are beyond help.
You already know the solution to rampant air-sickness (motion sickness)… pilots have learned that keeping their heads as still as possible mitigates the inner-ear fluid from sloshing too much and makes it more difficult to be incapacitated because of motion sickness. I know fighter pilots love to make riders sick, so I’m sure ‘keeping your head still’ probably is only so effective; I’m sure there’s limits to how well it allows someone to cope with 5-9G’s and rapid changes in direction. But I (coming from a family of 5 pilots) would even take a back-seat ride in a fighter over anything in space, besides maybe doing an orbital run in a space shuttle type spacecraft that lands on a runway. That would be the only thing that would appeal to me more. Just going up and then floating down wouldn’t do much for me. The launch would be cool but so would it be on an F-18 (or better yet, an F-15) and the landing would be awesome and you have such a better view of your surroundings when the pilot inevitably does tons of aileron and barrel rolls, and there’s constant changing of directions, so it seems cooler and more complex of an experience than a virtual launch and floating back to earth on a parachute INSIDE a pod without very good visibility. Aside from the power of the initial rocket launch, and the view from its apogee, everything else is sub-par to every other aspect to a ride in a supersonic and highly maneuverable fighter plane. I can see the “prestige” playing a factor in some people’s decision making, but aside from some ego trip of saying you’re among the very few to have been to space, the actual experience is probably not as comprehensively enjoyable. But let’s be real; either of those would be fucking incredible to do. I’m old enough to have been a cockpit during a commercial airplane landing, and it was utterly incredible and thrilling. Couldn’t imagine a hyper-maneuverable aircraft.
Scott, could you talk about the difficulties of try propellant engines. The source of all knowledge, Wikipedia, talks about the Rocketdyne test and the RD-701 but is quite short.
I've heard of theoretical proposals for a lithium-fluorine-hydrogen engine, apparently it's hard to keep the lithium molten hot while having the others be cryogenically cold, I'd imagine the fluorine alone is hard enough as-is
Tri*
Big Gemini reminds me a lot of the TKS... But, I suppose the TKS was something of a reaction to the MOL.
Scott, you elucidate that the Jovian human exploration problem is essentially a propulsion problem. There's good reason to believe that building bigger spacecraft can mitigate all of the problems of long-time-in-space (essentially radiation, microgravity, and psychology). There's (after all) a reason why all the incarnations of the Starship Enterprise are so big :)
Love this episode very interesting stuff, actually this is my second time watching it, thank you Scott
15:40 According to holographic principle an outside observer sees you slowing down as you approach a black hole, getting redder and fainter and being SMEARED on the even horizon. There is a video on YT from Susskind about this.
Every proton IS the whole universe. All of them. Holographic. If you shrink down to the subatomic like antman, eventually you would drop out of the sky back to we’re you started, 1 iteration down.
@@trapperjohn6089 Whatever you're smoking must be strong.🤣
@Eric E Well, considering, Susskind was one of the authors of the Holographic Principle you can't get it fresher than from the source.
@arcadly the smearing was conspicously missing from scotts black hole talk, but he did notice the red shift to blackness, so he still scores high on it. :)
poop shield activated!
Falling into a black hole: You are right about the red shift making things disappear, but to get more specific, the red shift will quickly get to radiation energies lower than the Hawking Radiation temperature of the black hole (assuming that Hawking Radiation is real; even if it isn't, the red shift will get to radiation energies so low that the wavelength exceeds the diameter of the event horizon, and no resolution of the infalling object will be possible even if you could detect the residual radiation).
Using propellant for coolant during Mars re-entry: If you do that, then the propellant will boil, and won't be available to use any more for getting back off the ground and back to Earth.
Your comment about skin diving on Europa made me think of the movie "Europa report" and gave me the shudders.
Every time I have to drive to Manlius I always think of this channel.
if you protect people in ship from radiation with "water wall" - will that water be possible to drink on arrival?
Yes, the water isn't 'storing' the radiation and becoming dangerous, rather it simply converts it to heat. The same way microwaving food doesn't make the food dangerous.
Should be - hydrogen-1 & oxygen-16 don't form radioactive compounds by neutron capture, so there shouldn't be any significant residual radioactivity
@16:24... I haven't seen that fairing for like nearly a decade... it was originally slated for a hypersonic kinetic platform...
About the "any infalling object can be seen on a black hole's surface" thing, I'd say the issues there are many, e.g. red-shifting and low intensity, and finally blur because the wavelength becomes bigger than the object. It's like the idea of a boiler plate. In theory, once heated, it won't ever return to ambient temperature, but approach it arbitrarily well if you wait long enough. In theory, you only have to measure the difference and can tell when it was used last. But in practice, the differences become too small to measure after a few hours.
With black holes, it's probably even worse, except for the mega- and gigaholes in the center of galaxies, huge black holes which are many light-seconds across. Those might be gentle enough in curvature to preserve an image for a few minutes, hours, or maybe even days. But that "image" will soon decay into a thermal "ping" rather than a "photo" which looks like the object.
Or you could compare the image to the afterglow on an old B/W TV screen. It is there for a second or two but loses brightness and shape rapidly.
These days, tungsten powder mixed into Ultra High density polyethylene is preferred instead of lead. Lead can neutron activate and become uranium. Secondly polyethylene works well to slow down neutrons which if it hits aluminum can spallate.
I heard Elon plans to use third class passengers as radiation shielding on cross ferries to Mars.
I'd rather take my chances on Mars than this God forsaken planet. I'm amazed our Politicians haven't nuked each other yet.
Not sure Elon plans much in that area. In his fantasies about "colonising Mars" are much bigger questions than radiation to answer. Getting there (reliably) is only the first massive and expensive challenge.
I would not even trust my car or bike to work for 15+ months without show stopping issues.
Yes, I heard he calls them Jack Dawsons.
@@5Andysalive specially if you have a tesla, lol, things break fast!
Shield Class. That one has legs.
Wow Scott - you really pulled out all the stops there!
I love Scott's shirt...The military(and probably others) phonetic alphabet...NICE!
Metric black hole? Does that imply there are Imperial black holes?
Yes, but instead of "dead stars" they're called "Death Stars" :D
@@StYxXx petitions IAU to rename "black holes" to "death stars"
Hello Scott, it looks like you’ve been little confused about neutrons. Lead is a bad neutron shield. Light elements are usually used for that for ex LiH and Borated polyethylene are common for compact neutron shielding. But neutrons are not a concern for a nonnuclear spacecraft because free neutrons decay in a matter of minutes.
Borated PE - cool! I guess beryllium's a little too expensive....found a it nice piece online for 8 K or so....
".000" x 48" x 96" Borated (5%) PE polyethylene, purple in color, compression molded
$8,788."
Yikes, that's not so cheap either! I had no idea free neutrons were a byproduct of high energy x-ray machines....
3:48 Bremstrahlung. I like your explanation.
I'll add "scuba diving on Europa" to my list of things I want to do. Come to think of it, it would be cool to imagine how one could build some sort of tourist operation there. Maybe I'll use it for a video. Great stuff as always, thanks Scott!
we haven't figured out how money is supposed to work (3000 years and counting, boom bust cycles with world wide wars inclusive) and you want to scubba dive on Europa?
At least you got your priorities in the correct order..
@@joansparky4439 Well, I'm an outer space anthropologist, so "figuring out how cultures might work in space" is kinda-sorta literally my job. But I get what you mean.
@@joansparky4439 I dont think the person talking about a future scuba diving spot on a far away Moon is responsible for the world’s economy
@@ValentineC137 well, the people who are supposed to take care of that (economists) don't seem to have a clue either, otherwise the whole thing wouldn't be treated like a 'miracle by god' but rather like an engine we have a clue about why it stutters/misfires/etc.
@@spacefaringculture3624 ..in case you are not joking - what does your knowledge/experience as OSA tell you about the behavior of individual lifeforms within a social setting (worksharing, specialization), when its favorable for the individual to behave in a way that harms the whole thing to function sustainably?
Do you guys have any theories for that?
If not, why not?
Further - have you ever considered control engineering relevant to these questions, as it's a field that deals with feedback-loops in complex systems?
Ever heard of the term 'reward hacking' that AI researchers/safety advocates throw around when dealing with AIs and their interactions with their environment to achieve their individual goals (at the detriment of the whole)?
I'm really curious what you think about all of this..
Ok but where can I buy that shirt
so you gotta realize that to pass the event horizon an infinite amount of time has to pass viewed from an external observer. if you yourself fall through the horizon you basically witness the entire remaining history of the universe behind you.
Smart move to develop the active shielding though - not getting far at interstellar field without considering it
Cheers for the video Scott. Regards from Cyprus and Scotland 😎 👌
Re fairings, yeah this is why I think it was quite genius of SpaceX to skip having a 4m and just go with a 5m fairing large enough for all but a few FH class payloads.
Good job Scott F. You broke him.
Best explanation I've heard about radiation in space. Cheers jock.
5:52 '[...] nobody likes swimming in you know molten
lava.'
You don't know my life!
If you used food as radiation shielding is there a danger to eating it?
Not much. Some nutrients are destroyed by radiation (like vitamin B), but the bulk of the food is unaffected.
No there wouldn't, it would absorb the radiation without passing it on. In fact, you probably already eat a fair bit of food thats been intentionally exposed to radiation as a way to pasteurize it.
Late night gang
On the subject of black holes, the best theory I've heard of to date is that they're Fuzzballs (made of strings). There's a very good PBS Spacetime video explaining this. In fact, this is the one and only theory I know of that actually makes sense as it doesn't result in any paradoxes.
Basically, in this theory, there is nothing beyond the event horizon. Spacetime ends there so there is no inside of a black hole/fuzzball.
Love the T-shirt. Having a hard time with people on the phone sometimes (making reservations, etc), I wish more people knew the phonetic alphabet.
There seems to be this idea that we'll live on Mars but does the lower gravity not make this impossible or at least not without severe health problems?
Martian school kids will be able to lift twice as many chairs 🪑
We simply don't know. We have huge amounts of data on living at 1G, lots on living in microgravity. In between that, we have exactly 12 sets of data, ranging from a few hours to about 2.5 days, contaminated by extended periods of microgravity on each side, of living at lunar (1/6th) gravity. This SHOULD have been a primary mission of the ISS, but...
We don't actually know. We have about 3 million years of experience living an entire lifespan at 1g and about 35 years of experience living a couple of months at 0g, but we have practically no experience with anything between 0g and 1g. (We have very limited experience living for a couple of days at 1/6g from the Apollo program.) So, the answer is: we have no idea what the effects are of living an entire life in 1/6g on the Moon or 1/3g on Mars. We don't even have any data from long-term experiments of say, living at 1/3g for a couple of weeks that we could extrapolate.
there's always been a human cost when exploring new frontiers, and I don't get why some people can get so hung up about it. people made ocean voyages to their near certain death all the time back in the old days, and tried to fly on paper glued to twigs. it ain't no big deal. you just have to go find out!
Human bodies would adapt, I've seen once simulation how humans would look like after multiple generations on Mars - basically, your grey aliens 👽
I'd think that the lightest elements would give the best protection per kg against charged radiation since they have the freezer nuetrons. So I get why they use water but why aluminum?
Re: Europa, no reason to go down under the ice is there? Just dig an ice cave.
@Eric E Sure but you could put the water in the walls rather than the full 10cm or whatever of Al being mentioned.
Thanks very much Scott, very much appreciate all of your interesting videos. Still getting nowhere trying to get those pesky 18km atmospheric scans in kerbal(I can't control the plane when i try your rocket on the plane method, lol).Everyone tells me career is no place for a noob like me lol. I'm getting better. think ive managed to remember to like after rewatching most of your videos now lol. I now like before i watch haha. thumbs up from not too far from your hometown (Falkirk) :). keep up the great work. my first search every weekend now :)
I think meant "nuetrons" and nuetrinos (negatrons) or WIMPS coming from cosmic sources, protons and virtual electrons or WIMPS coming from our local star. If protons were coming from both charged bodies (earth and sun), then the earth would de-orbit and our galaxy would fly apart like a broken supermagnet. I'm sure you just said 'protons' twice by mistake, a slip of the tongue that you didn't notice during editing. Sorry for pointing out this minor discrepancy. I fully respect your authority in communicating the science behind our rapidly evolving cosmology and humanity's bright future in space. Thanks for all the hard work you do in entertaining and educating the content-hungry web of life on this lonely planet. Cheers, Mate!
When one on of my phys/bio courses got around to DNA, I asked my professor about interstellar radiation and how dangerous it could be. Of course I got the answer "that depends on the strength of the shielding and amount of time exposed". She then said that, without shielding, the radiation will be affecting every organ in the astronaut's bodies, including their brains. So, over a six month journey, while the astronauts may very well "survive" the trip, they likely will be in ill health and a tad batty when they arrive. Well, that doesn't sound fun.
Can we see more about Uranus.
cosmo-skymed launch had amazing side-view of separation and boost back
Outstanding. Thanks for the video.
*Scott, I have a really interesting question that I'm sure others will love: how many people could the ISS support for one year? Assuming we flew up resupply missions as needed, of course*
If you also think it's a good question, please upvote it; otherwise he's never going to see it
Another great video Scott. Thanks for uploading and I hope you’re doing well!
Always good. Always interesting. Thank you
15:05 “it all sort of fits together and makes sense” yeah alright, totally makes sense
Great Q & A episode Thank You!!
Scott almost played the blonde card on that event horizon question. Never thought i’d see the day!
Lead blocks gamma rays but is fairly neutron transparent. The Russians used lead as the coolant in the reactor of Alfa class submarines. For blocking neutrons you want hafnium as it is the beginning of a long chain of high neutron cross section elements.
You also want to be about 3 meters away from your aluminium radiation shield to protect against the very short lived secondary particles resulting from stuff hitting the aluminium.
Kerosene is not the most efficient rocket fuel particularly for deep space operations but it is easy to store and a good rad shield.
About the notion of a black hole appearing to be covered with frozen objects near the event horizon--in Misner, Thorne and Wheeler's text there's a section where they talk about this and point out that the objects wouldn't just appear to slow down, they'd also get redder and dimmer, and for typical black holes the time of emergence of the last visible photon would be fairly short. So you wouldn't be able to see a voracious black hole's event horizon covered with old frozen debris; if you could get a clear look, it'd just look like a black hole.