Gravity Assist Speed Limit, Double Gravitational Lenses, Phones in Space | Q&A 266

[@cjc363636]

Telescope moment for me was my mom - RIP - about 30 years ago, in her 60s, realized the moon was really a spheroid - it was the shadows in the craters along the terminator line and she realized the moon wasn't a flat disc in the sky - not that she thought that, but she never really thought about it, I suppose. I remember her reaction was like a kid. It was one of the best 'grown up' moments with her I remember.

[@gpspilot1]

Gotta love this ginned-up narrative about "Elon Musk polluting the night sky with Starlink." Prior to Starlink, if you were observing a given astronomical object with a ground-based telescope, the odds of your image being spoiled by a satellite flying through were incredibly small... something like 10^-8. Let's conservatively assume that Starlink makes the situation three orders of magnitude worse. Now the odds of your image being spoiled are 10^-5. Still incredibly small. (Note, I'm not talking about long-exposure shots with a wide field of view, that take in many astronomical objects. Yes, you will get satellite streaks in those images. I'm talking about narrow-field-of-view images of a single object - which is the only kind of image that has value if you're studying a single object. Of course, satellites must be illuminated by the sun in order to make those streaks. Just time your shot differently, when Starlinks and other satellites are in Earth's shadow, and the streaks are gone.)

[@paulcooper8818]

I had nothing but good experiences ordering from Orion Telescope and the staff was super helpful and friendly.

[@donsample1002]

My answer to Hadante: every dime spent on “space” is spent on the ground. It goes to engineers, programmers, fabricators, electricians, janitors, cafeteria workers, gardeners, PR flacks… A billion dollar space probe launch represents the salaries paid to thousands of workers who built and launched that probe.

[@MaxBrix]

Got to better than the trillions spent to blow things up.

[@smorrow]

Arguably a better answer than Fraser's since he just talked about basic science (and science being basic or applied is orthogonal to what its funding is - and it's not that privately-funded basic science is some kind of "technical" possibility, either). "Job creation" doesn't really justify a government programme that didn't have something else actually justified about it, though (except it often does, because so much of a professional economist's work is just crafting big-brained _sounding_ jargon that confirms what a government wants to hear).

[@darthrainbows]

While this is true, it's not addressing the objection that is being raised. The objection I hear is that every dollar spent on space could be spent on solving a problem here on the ground - climate change, poverty, immigration, crime, cancer, take your pick, depending on the political leanings of the objector. I think the appropriate response is that we can do more than one thing at a time. Spending this money on space provides all these basic research benefits, as well as tangible innovations that get used in every day life (the classic example being velcro). We can do space and *also* spend money on solving problems closer to home. The reason we haven't solved, or aren't making progress in, those other problems isn't because of space money; it comes down to one of two things: either the problem is intractably difficult to solve (e.g. cancer) or there isn't sufficient political will to actually solve the problem (e.g. climate change).

[@DavidMcMillan888]

Fraser, after slingshotting through all the major KZbin science channels with real people and bypassing the constellations of bogus AI channels, I must award you the preeminent personal title as the best explainer of heavenly phenomena. Yes, above the 1m-subs placeholders because you not only know of which you speak, but clearly, summarily and passionately enlighten your audience. The award has no name but after 60+ years of watching Earthlings’ videos, I nominate you as “One of the Top Flyboys in the Know-how Department”. From where I sit, more coveted than the Fields Medal or Nobel Prize for in translation of a universal language, it means, ‘He who makes others understand.’ Thank you, Fraser.

[@Raz.C]

"...of *what* you speak," not "...of which you speak."

[@noelstarchild]

​@@Raz.CHa! Like "to boldly go" when it should be "to go boldly".... you are of course correct, but Star Trek is responsible for a lot of bad English.

[@briandeschene8424]

Your explanation and visuals of how interferometry works and how it has been accomplished was exemplary. I hope you realize how well you are serving the astronomical endeavour of science by explaining how its work so well to the general public. Kudos to you sir!

[@EditioCastigata]

46:00 X-ray astronomy. Always skimped on. What’s the latest in discoveries and tech? Any sensor fusion with the other big projects?

[@hawkbartril3016]

Dude I just can't pick the best question for this week because they are all good. What happened in the short break you took in doing Q & A sessions? It sure gave these people some great thoughts, which I think is brilliant. So a big thanks to them and you for bringing it all together

[@realfist1]

Hi Fraser, About your request for suggestions about who to interview, how about anyone researching advanced ideas such as FTL propulsion, Electromagnetic shielding for spacecraft, artificial gravity (including the hunt for the graviton) and other frontier physics. What do you think? I’m sure it would be popular.

[@tcarr925]

Jenev my fav question. So could you interview some Astro Navigator that computes slingshot courses or who invented "Slingshot" ? The people that navigated Cassini to fly through the Enceladus atmosphere and 'sniff' it would be incredible. They navigated something 800M miles away. Sounds like some pretty precise navigation.

[@NewsandScience]

I vote for Alaris as top question. That a cubesat with a side length of only 3.9 inches or even just 1 inch can be launched economically is encouraging to small tech companies or small science organizations--even possibly a group of amateur scientists--indicating a real potential to adding to the body of scientific knowledge. I'd rank Dakara second as it addresses the ever intriguing nature of black holes.

[@bobbyjones2112]

This is a great show. I’m really impressed!

[@b.r.409]

I have learned by watching your show about the time dilation of material that falls into a black hole from our perspective. From our perspective, it will take till eternity for any material to pass through the event horizon.

[@melantorja]

We want a SPACE ORCS specialist!

[@mathewherges397]

On the space race thing. I'd agree with you. I'm not a competitive person by nature. I feel like I never know enough and am always looking for the next new thing. I'd love for our efforts to just be about continuing to find new things. I feel like SpaceX's mission encapsulates this the best to date. Their mission to focus all their efforts on making life multi-planetary help to ensure that our future can be to continue to ask more questions. It's awesome!

[@greggweber9967]

20:32 In the same episode of The Astronomers as The Sidewalk Astronomer, John Dobson a group did a version of that with VHS cassettes.

[@chris-terrell-liveactive]

Topic suggestion: developments in autonomous and intelligent rovers for the further missions. For example, I'm surprised that we still don't have a rover with legs, similar to Boston Dynamics "dog" robots, that could cope with rough terrain better than wheels. Could some drone swarm approaches offer advantages? And much more.

[@YeenMage]

Nice answers. I was surprised with the answers to some because I missed learning those knowledge for some reason. Also yes, Saturn is also the first planet I ever saw through a telescope and it was a magical and unbelievable experience seeing something of that shape

[@TheJimtanker]

Cartego When I was young, my brother let me see Jupiter and the Jovian moons through his telescope. That was the beginning of my love of space.

[@mrln247]

More about Solar/Magnetic soaring if you can, actual flying in space not just falling with style.

[@budbud13411]

Another awesome video. Your channel is so great 🎉

[@mikedavis4214]

Hi Fraser, your description of a Black hole is about a static non-rotating Black Hole which may not in fact exist. That solution to Einsteins General Relativity equations is the Schwarzschild solution. Generally Stars rotate and since angular momentum is conserved, it is thought that Black Holes formed from the collapse of Stars are best described by the Kerr Metric which describes rotating axially symmetric black holes. Other solutions include the Reissner-Nordstrom (charged non-rotating black holes) and Kerr-Newman ( charged, rotating black hole). Take a walk down the rabit hold of a Kerr Metric black hole when time permits. I'm sure we will find the experience as presented by you to be delightful.

[@HebaruSan]

A question that I'm curious about... What happens to all the propellant that shoots out of our rocket nozzles? Does it mostly re-enter the atmosphere? Does it fly out into solar orbit at escape velocity? Does some of it end up in Earth orbit? Similar question for the material that "burns up" in the atmosphere - will we ever get that aluminum, plastic, etc. back?

[@treasurehunter3744]

First, to your propellant question: Most propellant used today is chemical, meaning its specific impulse, and therefore exhaust velocity are below the orbital velocity or even the escape velocity of earth. Therefore any propellant used lifting of, or in orbit of earth will very, very likely to reenter and join earth again. The only exceptions might be hydrogen fuel at high orbits, or outside earth's gravity. To things that re-enter, that is it slowing down enough to get trapped by earth again. It will be a fine mist or perhaps dust that will come down in the ocean somewhere.

[@rogerphelps9939]

The speed gain of a gravitational slingshot depends on the speed of the spacecraft relative to the black hole and the speed of the black hole relative to the galaxy. Since the departure trajectory of the spacecraft relative to the black hole is the mirror image of the approach trajectory, only in a different direction, the departure speed will still be no more than double the speed of the black hole relative to the galaxy. That means that you would need hundreds of gravitational slingshots around stars or black holes to get anywhere near relativistic speed. The only advantage of using a black hole is tthat its small size allows the spacecraft to get closer which allows for a bigger change in directtion.

[@maschwab63]

How about an Interferometer with the LaGrange points 60 degrees ahead and behind earth? Laser / pulsar timing between locations to determine offset. Maybe even a third behind the moon with Webb.

[@123seven3]

Not a scientist. I have a high school education but an interest in space and a tendency to think until I've reached a logical conclusion that aligns with the information I have, which is not scientifically rigorous or educated. So what I understand about interferometers is that they are basically analog, not digital, since the light from the telescope doesn't get captured immediately like your phone camera, it's funneled into a series of fiber optic cables or just open mirrors, then recombined physically at the interferometer. The location of these machines and mirrors is so precise that breathing on one too hard would put it out of commission, and it would take days to fix. If you had telescopes at L4 and L5, and an interferometer at L2 or on Earth, you theoretically could make that work, but it would be a requirement that the orbital periods were exactly synchronized to a ridiculous degree, like nanometer precision. Not impossible I'm sure, but prohibitively difficult. Radio is digital, microwave hits that limit, infrared and above is analog. The limiting technology is atomic clocks, so maybe if we had some kind of "quantum clock" that measured, like, the vibration of an electron or a proton we would have fast enough timekeeping to digitally interferometize(?) infrared or visible light. Pulsar timing won't cut it, I have to imagine at the scale of earth's orbit that gravitational waves would completely invalidate any attempts. There's a possibility that if gravity waves are the problem we could listen to the gravity wave background and only validate results that occur during still spots but I'm sure there'd be other problems. I have to imagine we'll push that limit eventually, because scientists are actively trying to push that limit right now. It's just gonna take a while before any common sense solution will be sufficient.

[@hermanrobak1285]

@@123seven3 Nanometer stationkeeping for a baseline of 1 AU or more, mechanically? That's a tall order. Maybe "lucky imaging" could be practical. Have a laser pointing from one orbiter to the other, as a phase reference. _Try_ holding the optical paths in phase, by moving mirrors, or adaptive optics. Capture the light in _very_ short intervals, or high frame rate, if you will. Discard the "frames" with high detected phase drift from the reference laser. Keep the few frames that are _spot on._ If only there was a photo-electric phase shifter or delay, with pico-second ramp times. Or maybe I am barking up the wrong tree. I'm not a subject matter expert, either...

[@rogerphelps9939]

The Lagrange points are nott massive bodies. Any focussing effectt would be extttremely weak.

[@rogerphelps9939]

@@hermanrobak1285 The LISA gravity wave detector is aiming to do just that.

[@olorin4317]

Also, follow up interviews with some of the interesting people you haven’t talked to in a few years would be cool.

[@jamesfowley4114]

Coopetition is the word coined by a Nascar driver/announcer that applies. They compete but also assist each other on and off the track. Sharing scientific results improves the outcome for everybody.

[@HansMilling]

I got a Mead 80mm refractor and their computer was so bad. Had it repaired multiple times and even got the whole telescope replaced, but the new had the same flaw. They all just started moving in a fixed linear direction, quite fast when you used the go to feature.

[@donwp]

Glad you asked; my topic - how are we still talking to the Voyager space craft. Why hasn't that knowledge all dissipated with time. Thanks!

[@walteratchison6245]

In your discussion about the issue of money "wasted" in space, it might have been useful to point out that money isn't just dumped into space. It pays salaries, buys goods, funds education, and lots more things here on earth. It is very much a stimulus to the economy and has a very positive effect on education and our socioeconomic systems.

[@lyledal]

Hi Fraser! Question: You mention the use of atomic clocks with interferometers. Do more accurate clocks mean better resolution for the interferometer? Will the introduction of nuclear clocks lead to even better interferometers?

[@OzoneTheLynx]

I think the topic I would be most interested in currently is quantum sensing. There is always a lot of talk about quantum computers, but from what little I heard about quantum sensors they are just as exiting an technology.

[@maschwab63]

How about very small camera behind each starlink for asteroid / satellite detection? They do have Starlink on Pitcairn Island for descendants of the HMS Bounty Mutiny.

[@surferdude4487]

If all Starlink sattelites were equipped with low power telescopes and downloaded their data to a computer with the right software, the Earth would never be surprised by an asteroid again.

[@TyLockton]

@@surferdude4487 Vera Ruben should solve that problem.

[@nazzify6417]

I live in a pretty rural tourist area (bortle 4), and it’s amazing how many people from the city complain about how it’s “too dark” and that we need more street lights.

[@MeissnerEffect]

Alright!! Looking forward to this and can’t sleep anyway. No reason really just the world on a seesaw for the next few days 😮😢😳😱🫡🤗🦾

[@mrfirewoodzipline9120]

Good explanation of using planets for gravity boost to speed up your spaceship. Do you think maybe thousands of years from now when maybe millions of spacecraft are using planets for speed boosts, you will start to effect the orbital velocity of those planets so much so that you will need to consider controlling how many spacecraft can do this? It is a very small reduction in speed but over time it adds up. Like the lunar tides slowing down the rotation of the earth.

[@bobbyjones2112]

The asteroid budget is one of the most important ones we have because that’s a probable extinction scenario, if we don’t have a way to change the direction of one headed straight for earth!😳

[@Akio-fy7ep]

The big problem with Starlink now turns out to be the upper-atmosphere aluminum pollution that will obliterate the ozone layer. I don't know if making them out of magnesium or something instead would help, but we had better force them to do something.

[@ScienceWorldRecord-org]

I hope this is not another problem. I believe China have started launching their 15,000 "Thousand Sails" constellation. Humans, one step forward, two steps back.

[@vgamedude12]

Typical "scientist" and thinker hubris and arrogance. They look into something a bit and think they understand every consequence when they don't have a clue.

[@parthhappy]

Probably Titanium than Aluminium?

[@digitalnomad9985]

No, we need a salvage yard in orbit that processes defunct satellites into orbital infrastructure. This is the ISRU principle applied to Earth orbit. Maneuvering between orbits doesn't require the delta-V of an orbital launch, nor the thrust, thus you can use high Isp ion engines and take your time.

[@JenniferA886]

Thinking in the shower, while listening to a podcast… respect 👍👍👍

[@faolitaruna]

Belote: archaeologists have the same nomenclature, where the first layer is the youngest. I think it is the necessity.

[@Joenerfhearder]

In a hundred years we may have scopes positioned to use the sun as a secondary gravitational lens for other "known" distant lenses.

[@shadesmadness4399]

On the cube sat topic. How feasible, practical, beneficial could it be to make a cube sat equipped with a strong enough camera that could go alone or accompanied by others to survey a planet and provide up close visuals and science with the benefit of being close to the objective?

[@ericsmith6394]

It fails in practicality. You can't fit much of an antenna on tiny satellites, so you need a 'mothership' to send the data back. There's usually a polar orbit where that larger probe can eventually see the whole planet as it turns beneath it. This is easier and more reliable than splitting up. Separate probes are good for cases where it does something that would lose the larger ship. Things like the DART mission and entering a lava tube or any atmosphere.

[@caerdwyn7467]

Asuria. I wanna know. QUESTION (sorta): You get a free 1u Cubesat ride to LEO or lunar orbit (your choice), downlink services, and a budget of a low hundreds of thousands of dollars to build. What would FraserSat do? Bonus points for going into some detail about your component selection, the component shopping process and the approval process. SHOW US HOW.

[@jamesleatherwood5125]

Speaking of cell phones in space, theres an app you can download that records when your cellphone camera sensor gets hit with a ray big enough to activate that pixel sensor.

[@rasputinsbeard3899]

So, a question about supergiant stars like Betelgeuse. As they are much, much less dense than, shall we say, "standard" sized stars, what effect does this have on its Roche limit? There has been a hypothesis that Betelgeuse may have a smaller partner, rendered invisible to us due to its proximity to the main star. Is it possible that in a supergiant star with such a low density, that another star could orbit the centre mass of the main star, but within its boundaries?

[@MagnumMatt09]

nice PFP, lol

[@rasputinsbeard3899]

@@MagnumMatt09 As is yours, good sir.

[@rogerphelps9939]

The density of Betelgeuse is far less tthan tthat of the sun. The Roche limit is not fixed and depends on the size and density of the object being disrupted. It is probable that the Roche limit of Betelgeuse for most stuff lies within the photosphere.

[@olorin4317]

I would like to hear more interviews with Sierra Space about anything and everything they’re dreaming up. Have you watched the interview with their CEO about six months ago? It had a few interesting tidbits. I’ve noticed that in the past year more and more people are talking about orbit as an active conflict zone.

[@ernstboyd8745]

this is a cool video format you can just click on the question you want

[@hodor3024]

4:10 judging by pictures I googled, it's 2.5x10x10cm.

[@charleslivingston2256]

Or 6.3 cm cube. Originally, U was a height for something slid into an electronic equipment rack (1U = 1.75", 2U = 3.5", etc). For cubesats, there isn't a rack, so they settled on just standardizing the volume. 1U is the volume of a cube that is 10 cm on a side.

[@hodor3024]

​@@charleslivingston2256 U = unit and in the context of cubesats it's 10cm³. While 6.3x6.3x6.3cm is arithmetically 0.25U, those dimensions are contrary to the purpose of cubesats.

[@donsample1002]

Inside your space capsule or station the convective cooling of a cell phone would work just fine. Cooling only becomes a big problem if your phone is in vacuum.

[@SK_2521]

Question: is there any research into Solar system wide internet? As DSN hardly will be able to support major colonization - like settlements off planet or telescope on the Dark side of the Moon

[@JROD082384]

*FAR side of the moon. It gets just as much sunlight as the side you can see all the time...

[@Nk36745]

Inflation as a topic for a video please

[@BitcoinMeister]

Future Topic: Serious/realistic plans for manned missions to solar system bodies other than the moon and Mars. Moons of Mars and clouds of Venus are fine, but other destinations would be even better. thanks

[@jasonalpha]

Love your channel, Fraser. I have a question. Is the Multiverse still just a theory or is it more than that? Thanks and keep up the good work. Jason

[@frasercain]

Still just a theory. There's no evidence it's true.

[@BillBakerB]

Nationalism as a "dirty fuel" for fueling exploration is a great analogy , thank you.

[@Goatcha_M]

How do interferometers see all the stuff in between the two images? Or is that just missed data like that blocked by the mirror in a reflecting telescope?

[@Goatcha_M]

The list of technological developments made possible by space exploration is immense. From satellite communications to car breaks and everything in between. Space Exploration consistently pays for itself 100 times over, or would if taxes were levied fairly anyway.

[@montyiscool11]

Fraser, perhaps a look at a few of these advances would make a good show.

[@montyiscool11]

Perhaps a look at a few of these advances would make a good show.

[@jimwoodford3984]

Questions for Question Video. Why are stars we see orbiting Sagittarius A* not showing any gravitational lensing?

[@richiebricker]

taking pictures of things at different with your interferometer principle, take a second picture months later and make the most awesome stereograph?

[@Flesh_Wizard]

Can we reverse gravity assist off of Jupiter, fall towards the Sun, and gravity assist off of the Sun and go insanely fast?

[@jimsmith9251]

Yes absolutely, that's how the Apollo missions slowed down to land on the moon, they just went the opposite way around the moon instead of with it, it's also what the Parker solar probe is doing to slow down and fall closer to the Sun.

[@fluffysheap]

You can get closer to the sun this way, but you can't use the sun for a gravity assist. You can't get a gravity assist from the thing you are currently orbiting.

[@jimsmith9251]

@@fluffysheap Correct, the PSP used the Earth and Venus to slow and lower it's orbit to the Sun

[@caldodge]

IIRC, some cubesats use cellphone hardware.

[@FrancisFjordCupola]

When it comes to basic research and mass extinctions, it is scientific fact that climatic changes are involved in all the big mass extinctions (including that one of the dinosaurs)

[@drdca8263]

For that last question, I was hoping you would give like, an equation describing the amount of a boost that a spacecraft would get from a slingshot around a planet in terms of things like, the mass of the planet, how fast the planet is moving relative to the star, how close the spacecraft gets to the planet, how fast it was going to start with, etc.

[@rogerphelps9939]

In the reference frame of the planet the departure trajectory of the spacecraft is the mirror image of the approach trajectory, just in a different direction. In the planetary reference frame the spacecraft has not gained or lost any energy. Now suppose a spacecraft is launched from Earth such that when it approaches the orbit of Jupiter it is pretty muct stationary with respect to the sun. From the perspective of Jupiter its approach speed is pretty much the orbital speed of Jupiter. Now suppose that things are arranged that, relative to Jupiter the spacecraft does a complete loop so that it leaves Jupiter on a trajectory that is tthe mirror image of the approach trajectory. Suppose the orbital speed of Jupiter is v. From the Jupiter reference frame the spacecraft approach and departure speeds are both v but in the sun's reference frame the spacecraft's velocity is now the sum of Jupiter's orbital speed and its departure speed, 2v. In general the speed limit for gravitational slingshots is twice the orbital speed of the planet.

[@Tara_Li]

This a second trick to use close approaches to planets to gain speed called the Oberth effect. Basically, at the closest approach, you fire your engines. Since you carried the fuel in, but you’re not carrying it out, you get a boost.

[@drdca8263]

Thanks to you both!

[@stevenkirkwood7039]

Considering the deflection of an asteroid’s orbit by even a slight amount is said to make a large difference over time in avoiding a potential impact, why is it not a more significant consideration of the long-term effects of orbital deflection of planets by using gravity assist maneuvers? Is there some mechanism of gravity on this larger scale (and like using GA maneuvers on BHs in the galaxy) that makes this negligible? Or is it simply that the amount it changes by for those scales only becomes significant millions of years or more later, so we ignore it?

[@Raz.C]

First time I ever saw Saturn in a telescope, it looked like I was looking at a picture of Saturn, as it appears in books, etc, rather than a real-time, live version of Saturn. Maybe it was the lack of background stars, or maybe it was how the telescopic version was identical to the textbook version... Whatever it was it seemed unreal, despite how real it really was.

[@zephyr9673]

Also worth noting Tektites, and micrometeor/space dust

[@zephyr9673]

Cosmic rays also cool

[@danielparra7999]

hi Fraser, I have a question that torments me: If the rotation of the planet produces the movement of the Earth's core and the magnetic field that surrounds us, in addition to the trade winds, why does the expenditure of energy not cause the movement to stop?

[@maschwab63]

Topic: Big Bang creating Helium / Lithium, Beryllium, etc. And first star creation. Lithium liquefies around 1600K, Lithium Hydride forms as a liquid around 900C. And when these molecules hit each other they stick together unless they achieve the boiling point so they would accumulate until Hydrogen starts to stick by gravity above earth size by Neptune's size.

[@KnownUnknown-i8r]

Ok Fraser, I have a question about bendy light. If black holes curve space and gravitationally lens, could a strong enough telescope with enough granularity allow us to see back in time. Can the light from our star or galaxy be reflected back by the event horizon by being bent around the black hole?

[@KGTiberius]

QUESTION: mental experiment: imagine a rotating tether probe with sensors/instruments along the entire length AND this probe was (mind experiment) 1 parsec long, what data could be gathered in the rotation? Now orient it to dip an end in a black hole (either rotating or a static (not rotating) dip stick (lol). Mind experiment: 1) material strength is unbreakable, 2) material is segmented to break if needed. Would it stop rotation? Time dilation implications? How would it break? What data value in the break up?

[@KGTiberius]

Data beyond the event horizon wouldn’t be able to escape, even if connected. Sure. But how would the time dilation work along the length of the probe? Relativity, but this probe is also one entity. I’m imagining it like a human dipping a toe in hot water. It takes milliseconds to perceive the burning hot water, so the toe is already burned before one could react. (Or other injury like severed.)

[@BestBFam]

Thank you.

[@peters616]

As others have pointed out there's a problem with how you describe gaining velocity from a slingshot. For starters it might be impractical to try to slingshot around a black hole because of debris but even if there were a clean one it might not be very useful. Absent changing direction, any velocity gained through the attraction of gravity going towards the black hole would be lost coming away from. You can steal momentum from a black hole that has a velocity relative to another object through a change of direction with respect to that object, but that would be very, very unlikely to get anything close to relativistic speeds.

[@frasercain]

You would get a gravitational assistant in exactly the same way you get one from planets. You're stealing a little of its orbital velocity around the center of the Milky Way.

[@1itim]

Taking (or giving) momentum doesn’t cause a spiral in to the sun (im sure fraser knows) it just changes the orbit a bit, its a once off. A spiral would need a constant force like atmospheric drag

[@blacksmith67]

So my old Motorola flip brick, in terms of electronics, would last longer in space than my current smartphone.

[@kenmccarty6229]

Interesting! The final parsec problem solved...by Aliens! Lol (ship gravitation assist by black holes)

[@Starman_67]

INTERVIEW IDEA I'm fascinated by globular clusters. Is there a research team dedicating their focus to studying the orbital dynamics of stars in globular clusters, as this must be an amazing place to map gravity wells and how space curvature fluctuates in such a densely packed volume of space. Also, whether there could be gravitational wave effects that one day might be perceivable.

[@PitchWheel]

Thank you Fraser! At what size would a planet be so massive to generate heat and support life without a star?

[@ericsmith6394]

At any size if the heat was from radioactive decay or tidal heating from orbiting something like Jupiter. You just need to avoid losing gas to space from smaller objects. If you mean heat from fusion I'm skeptical life as we know it could survive any situation where that's happening. The chemistry we depend on only works in a fairly narrow pressure range. Too low and we can't diffuse enough oxygen into our blood (or water boils in our cells). Too high and it impacts chemical reactions we depend on. Even if you had a brown dwarf with the right temp and pressure this would probably only exist within a narrow altitude band far above any surface. Anything growing there will find it incredibly difficult to stay in the survivable zone, so I don't see how primitive life could get started.

[@PitchWheel]

@@ericsmith6394 my thoughts derived from the fact that just by digging few kilometres down in earth crust, the temperature rises. I don't know the cause but I think it's just for pressure. This heat could reach the surface or create some kind of thermal vents without radioactive decay. I was wondering if this could be a possibile scenario

[@ericsmith6394]

@@PitchWheel yes and it's not unlike when the Earth froze over and life survived at the hydrothermal vents. The Earth has heat leftover from its formation, radioactive decay, and a small amount from tidal heating. There's plenty of heat in there. All planets will have formation and radioactive heat. Jupiter's moons get a lot of tidal heating, but Earth's moon does not because it's tidally locked and in a circular orbit.

[@PsRohrbaugh]

I wonder what the balance is between shielding modern chips with lead is compared to using older chips.

[@persona2grata]

It might be possible to look below the event horizon of a black hole under certain circumstances. The event horizon is simply the points along a sphere where the gravity of the black hole is such that not even light, or traveling at the speed of light, allows you to escape the gravity well if you get any closer. If you have two black holes orbiting one another, the line that defines the shortest distance between the two masses represents a region where the gravity of each mass is acting in opposition to the other. This means that the event horizon should shrink for each black hole, allowing a well placed probe to observe further inside each black hole than you would otherwise be able to. Or at least, that's the way it seems to me but I'm not an astrophysicist so perhaps I'm missing something.

[@JROD082384]

With two supermassive black holes beginning the slow dance of merger, you could theoretically deploy a probe that had a secondary probe attached via an umbilical such that the secondary probe passes through the event horizon, and images could be delivered up the umbilical to be relayed by the primary probe.

[@persona2grata]

@@JROD082384 Yes, absolutely. Supermassive in particular would be desirable because of the lack of tidal forces. When I was originally thinking about this I was actually imagining something much smaller, with two or more man made black holes of only a few million kg of mass or something that would last an hour or two before evaporating, then placing them in very specific orbits that would allow you to get arbitrarily close to exposing a naked singularity. It would be incredible to observe what happens when space time breaks down.

[@Spedley_2142]

Question: If fusion gave us 'unlimited' free energy would it be possible to recycle waste by heating it to a plasma in an arc furnace and then use electric fields to sort/refine every atom by mass into individual storage bins?

[@jblob5764]

For the US folks.. a 2.5cm cube is a negligible amount smaller than a cubic inch which is a 2.54cm cube. ABSOLUTELY TINY for a satellite. Makes me think of those tiny tornado probes from the movie Twister 🌪️

[@w3vjp568]

Most of us Americans are familiar with the metric system; despite the deep-seated cultural resistance to replacing our everyday units of measurement, you won’t often find anything but metric system in use in medicine or science.

[@jc441-i3q]

@@w3vjp568 Both Metric and Imperial are superior to the measurements the media like to use like "8 school buses long" "heavier than 3 elephants..." etc 😏

[@Otisthelesser]

I figured it out. In proof that the US will use anything but the metric system. 50 BMG is 12.7 mm, so it just a little smaller than 2 of those. lol.

[@jblob5764]

​@@Otisthelesser 12.7mm is exactly a half inch so thats a great conversion 😂 and 7.62 is between 1/4 and 1/3 of an inch

[@_kreetch9231]

I’ve lived abroad Im a dual citizen and honestly we are onto something with the imperial system. Inches are fierce

[@tehaury]

A .25 U cube sat would be 2.5cm x 10cm x 10 cm. A 2.5cm x 2.5cm x 10cm would be a 1/16 U. (2.5 x 2.5 x2.5 would 1/64)

[@JT-ky9gr]

@@tehaury a U is not a measure of volume but length of a side

[@tehaury]

@@JT-ky9grit’s a standard volume. 10x10x10. A 1.5U is 15x10x10

[@JT-ky9gr]

@@tehaury you're correct

[@idodekkers9165]

Hey Fraser, when you are talking about metal polluted stars, are you talking about astronomical metal or periodic table metal?

[@frasercain]

Anything higher than helium on the periodic table is considered metal by astronomers

[@idodekkers9165]

@@frasercain yup - that's what I was asking.. : ) if astronomical metal or actual one, thanks

[@CoreyKearney]

The cell phone question has been rattling around in my head since the mars helicopter launched, was it not built with redundant consumer grade cell phone soc's? So the **Question** I have is what was the result of that? How many upset events occurred? How did it recover from them? Did they use ECC memory? Are we over doing it with rad hardened 45 nanometer chip designs from the 90's? How much more processing power could we fling at Jupiter on a smaller node? Those are the questions I had hoped the mars helicopter would answer. Unfortunately the media is to enamoured with FLYING ROBOT ON MARS! to really find any details about this.

[@SeanBZA]

The flying robot was built with older generation mobile parts, and also was not intended to last long, the original mission brief was 5 flights, and around a week of life. Standard 30nm processes will probably survive this, most likely will be single bit errors in the memory, easy enough to overcome by using checksums and hamming code on the data stored, or accept there will be flips for things like images. Program memory is the issue, the EEprom will slowly degrade with radiation, so you use older large SLC flash, have smaller program memory size so the cells are larger and older process, and back etch the wafers to make them ultra thin, then grow a SOS insulator on the back. There have been a good number of cubesats launched that used off the shelf phone boards, just stripped of the useless things like displays and digitisers, and with rooted roms that will power on immediately battery power is connected, and which are activated by the cubesat launch removing a safety switch, connecting the battery. Then they use standard cameras, and use some extra volume with a SDR radio that provides the right bands, if the actual RF SOC cannot cover the bands needed at power, possibly only using an external amplifier chip to boost power up to 5W for the integrated antenna. After all, as cubesat is normally in LEO, they typically operate for only a few weeks, and then either fail due to radiation upsets, or come out of orbit and burn up. Standard cylindrical cells, as pouch cells do tend to puff up in vacuum.

[@CoreyKearney]

@@SeanBZA But it flew for much longer, on mars! It was taken down by a aeronautical failure. not a chip failure. The SOC's were top spec for when it was built, so not 30 nm either. I'm looking for real data collected not assumptions, no matter how reasonable they may be. LEO doesn't really answer these questions.

[@Raz.C]

The smaller the chip architecture, the more runtime NEEDS to be dedicated to error-correction. So it's not essential to use older hardware, but it IS optimal.

[@tygical]

FLYING ROBOT ON MARS!

[@noelstarchild]

​​​@@tygical, pretty incredible isn't it? And in an atmosphere far less dense by a cubic meter factor of 10³....definitely a Wow!

[@digitalnomad9985]

"Chance of cosmic ray interference increases with complexity" Also inversely proportional to logic component size. Larger lithography process means less susceptibility to cosmic ray interference. Complexity vulnerability scales linearly with complexity. Size complexity graphs different. Above a certain component size, cosmic rays simply can't immediately flip a bit, they're not individually energetic enough. Cosmic rays need to wear down large components gradually over time by demolishing the crystal structure.

[@69woof]

And now a question if we could reach near speed of light travel how are we going to slow down and what and could we carry enough fuel to do so or can use planets and black holes

[@hengehog838]

Let’s put disc golf course on the moon and mars. How would frisbees fly differently? Inside a crater could have baskets

[@bluered3228]

Wouldn't they just fly in a straight line with the only motion being that created by the throw and gravity?

[@encodedpr]

love the stargate planets

[@scottmuench6855]

Is there a way using orders of magnitude to describe the very smallest that we can see with tools the middle of the scale of life that we can see with the naked eye and the extent of the observable universe that we can see with tools? What would the orders of magnitude look like for each of those?

[@limabravo6065]

I live in the states in Pennsylvania specifically and satellite internet is the only option so starlink is a massive good for people in this area

[@AnthonyNolan-w5u]

I keep forgetting I have a very old phone, and I have 3 computers for doing computer things, so I don't exactly tax the phone processor by watching YT on it, for instance. Yeah, overheating would be an issue. So would the cold of the shadow, perhaps. It would probably crack at least the case after a few orbits. Given quality these days, maybe the circuit board too

[@Zenith_123]

Q: How can we see light from the early universe by looking at a certain area of space? Would that light not have already shot past our position relative to that event billions of years ago. How did our matter get ‘ahead’ of the light from the earliest time in the universe.

[@jimsmith9251]

I'm a little confused about the gravity assist, i totally understand that it's an orbital assist really but you say you would get an enormous speed boost from a black hole, are black holes normally at the centre of any gravity well? and if the black hole is not orbiting anything like a star then the speed boost received upon approach would be negated on the outward phase. Please let me know what i have gotten wrong here as i know you know what you're talking about. Thank you for your videos, much love from the UK.

[@davidk.8686]

The black hole and infinite density "problem" is just a mathematical "problem". If the infinite density is limited to an infinite small volume (hence "singularity"), it may have very well a finite mass. It all depends on how fast the density increases with decreasing volume around the singularity. Conceptually there isn't any problem at all, regardless if a singularity actually exists or not. It"s just very fundamental math.

[@czootv]

Question - if a warp drive existed would the passengers on the ship experience time dilation in the same way that passengers traveling at relativistic speeds with either "traditional" propelled ships or ships with constant 1G acceleration?

[@charlescouncill]

What size cube for a cell phone tower?

[@danbhakta]

The counter point to terrestrial based telescopes...launches are becoming cheaper and space based telescopes would be cheaper to put up without offending the devotees of mountains and cutting through the light pollution and atmosphere. No land acquisition needed. An entire fleet of telescopes can be launched where astronomers benefit by abating the fight for time at any land based observatory.

[@rogerphelps9939]

Good luck with orbiting even a 30 metre optical telescope.

[@danbhakta]

@@rogerphelps9939 I don't understand. Why is luck necessary?

[@Bungo71]

How does something that is a singularity have a spin to generate an accretion disk (and "poles' from which gamma ray bursts escape from? In theory, anything that gets into an orbit around the singularity could come from any direction, so why is there a rotational plane from for something that has no dimension to spin in/with, and generate and the physical structures in the classical 3 dimensions + time?

[@robertfindley921]

Space tested and certified components are *very* expensive because in part they can handle the extreme forces during launch. Launch a normal cell phone and likely it would break. Also, sound needs an atmosphere to listen and talk on the phone. So in the ISS or something, OK.

[@Sprengstoff]

Jenev - But once you have slingshotted of a few black holes, how would you turn on the brakes and land on your destination planet? Thank you for a great show, i try watch them all :)

[@frasercain]

You target different black holes in the target galaxy

[@ncdave4life]

16:00 _"Galileo thought it_ [Saturn] _had ears"_ Ha! I didn't know that!

[@Ken-rq9xr]

Do all black holes evaporat to a micro point before dying.😮😊