Why No Missions to Mars' Poles? What Does X-37B Really Do? Why Continue With SLS? | Q&A 269

[@frasercain]

Oh, just to be clear, that wasn't a sponsored segment at the end, I just wanted to talk about the tech.

[@joshm3008]

What? No quirky ad sponsors like other channels? Blasphemy!

[@FirstNameLastName-okayyoutube]

I love your work even if there is still some unsettled topics that you bring up, I think you have some of the most courage of anybody talking about the physics.

[@jimmirow]

​@meraxitech??what??

[@michelleloader5560]

Hi❤❤❤❤

[@adamsutherland2593]

@@frasercain I had a silly idea watching your black hole/dark matter video, basically what if space-time is a non-Newtonian substance to replace dark matter. Couldnt find anything on google so tried ChatGPT and was able to make a quite convincing theory including how if might work with the big bang, inflation, cmb and general relativity. Was even able to get it to make an equation( without any values) to make it work. I dont really expect it to go anywhere but where do i go, who do i ask to help takexit any furter or knock it on the head. Also a maasive thankyou for making content that brings back the childhood curiosity thats so hard to find nowadays 😊

[@MichielHollanders]

Very excited that the Europa clipper is getting close to launch!

[@andyspoo2]

If life exists anywhere in our solar system (other than us) it's on Europa.

[@lazloperry5242]

It's gonna crash at launch rofl

[@jimmirow]

​@@andyspoo2there's a bunch of life coming in our future finds. Hopefully they are not like us

[@bjornfeuerbacher5514]

@@andyspoo2 Or Titan. Or Enceladus.

[@joshm3008]

In a world full of ai videos, one man stands strong...

[@zelrex4657]

There are quite a few good sci communication channels. ✨ I recommend Sci Guys if your looking for a good podcast

[@vinniepeterss]

yeah....

[@notgreg123]

There's a few more... But not many

[@petevenuti7355]

For some reason I hear the music from TV show Knight Rider when I read that.

[@jamesleatherwood5125]

​@@zelrex4657i add Scishow, Science Asylum, Steve Mould, Be Smart, PBS Eons, kurzgesart, Smarter Everyday, and Astrographics to that list

[@marklapierre5629]

Black hole sun. A true classic rock tune.

[@RaulGnaga]

In a recent episode, you highlighted how CMBR photons feed black holes. Apparently, even for a black hole of just 6 solar masses, Hawkins radiation will not exceed the CMBR contribution until the CMBR drops to 1.5°K! When will Sagittarius A* start shrinking? Will all stars in the milky way and local cluster have already died by then?

[@TarisRedwing]

That seems like such a bad excuse to have not gone back to the poles of Mars. "It didnt work once so we send 10 more to other parts of Mars instead" lol what kinda scientific logic is that.

[@bjornfeuerbacher5514]

Very probably, the other missions were already planned and in development when that one probe crashed, so obviously they first went on with those other missions, instead of planning for another land at the poles then!

[@acanuck1679]

My vote is for "Belsa". The question about gravity and whether objects that are very far away exert some gravitational influence on us here on Earth was quite good, too. Then again, your entire webcast was excellent. Thank you.

[@Knsy]

New bottled mars ice cap water, coming in 2073

[@arthurballs9632]

Radioactively Refreshing

[@Kru12794]

16:12 Imagine actually asking a question like this unironically...

[@geohondo]

Hey I'm definitely not a musk fanboy.....just a science, scifi lover and I love space exploration. I hate Elon but love spaceX. How much does SLS cost for its 1 time use? I feel like investing in non reusable rockets at this point is just wasteful. And Frasier explained why very well to me. Love this channel

[@notgreg123]

​@@geohondothe point of SLS is that it keeps all the contractors happy and is popular in Congress. This is vital because if Congress isn't happy with NASA then things go south. Ironically SLS is providing a hell of a lot of NASA's funding right now

[@sheepwshotguns42]

another 10/10 video, give or take a very accurate plus or minus 40 million.

[@andreravenna4435]

Thanks for answering my question :)

[@strawberryfields5074]

You're very welcome. Do you have any other questions?

[@ezpzenterprisesllctennesse4443]

Fraiser, I’m one of those kids born during the SPACE AGE. Moving from Long Island to Palmdale California was a dream come true. My best friend at the time was Chuck Scott. His dad took us to some wonderful areas in Edwards that civilians rarely see. Jumping forward I’m now a 60 year old dreamer but my friend Chuck still works at NASA. I hope that NASA is able to get rid of the SLS Launch system but keep Orion. Use Falcon Heavy to launch Orion and other equipment along with Space X !

[@unclvinny]

Edora was my favorite question, but the Mars poles question was a close second.

[@MaxBrix]

A good way to imagine gravity diminishing is to picture a sphere around the object. The sphere has a certain amount of gravitational potential acting on it. A larger sphere has the same amount of potential spread out over a larger area so it is less in any area. The amount of potential on any square meter of the sphere changes according to the inverse square law. The total potential on the whole sphere is always the same no matter how far away it gets.

[@bjornfeuerbacher5514]

Replace "potential" with "force", then it's right. The gravitational forces decreses according to the inverse square law. But the gravitational potential decreases according to simply the inverse distance, no square involved there.

[@AttackChefDennis]

Leaving your home in an evacuation is so freaking scary and hard to do. It's all your property and belongings. I haven't had to evacuate, and I have lived here in Broward all 57 years of my life. Hurricane Andrew in '92 was the worst.

[@rm-gh1co]

​@@AttackChefDennis A few months ago I got an imminent evacuation notice due to to a fast-moving fire a couple of blocks away. And I wasn't at home. Lots of evacuations. Even the humane society. Fortunately, because it was close to the airport, A helicopter picked up a load of water in between him and fireman dowsing the fire, They were able to keep it from spreading. But, I've known many people who lost everything to fires in Oregon. Everything.

[@AttackChefDennis]

@rm-gh1co Wildfires are no joke! I'd much rather have a few days notice with even the biggest hurricane.

[@treefarm3288]

You have my sympathy from tropical cyclone-prone north Queensland. We've had several. The frequency doesn't seem worse, but the intensity is.

[@JAGzilla-ur3lh]

Ardena. I vaguely remember hearing about the Mars Polar Lander when I was a kid, but I'd forgotten all about it. Yeah, that's really a mission that needs to be attempted a second time.

[@IsaacKuo]

One polar mission proposal worth checking out it Mars Geyser Hopper, which would be similar to Phoenix, but designed to rocket hop a few times during the mission to move from place to place. Its focus would be to study polar geysers, which we haven't directly seen yet. But this highlights a "challenge" for a possible manned mission to poles. I do agree that polar resources would be excellent for a manned Mars mission, but there are some "interesting" terrain challenges that don't exist at lower latitudes.

[@jblob5764]

Im extremely excited for IFT 5 on the 13th

[@ioresult]

Matt O'Dowd recently made a couple videos about wether gravity is quantum or not. In particular, about its fuzzyness. Would that mean that below a certain treshold, some kind of Eisenberg uncertainty prevents us from measuring gravity very precisely? If so, then is there a relation between a given mass and the distance at which measuring its gravity becomes impossible?

[@DanWeidert]

Love this channel. I might suggest reviewing the use of accurate versus precise. A time of 5:32:45 PM is more precise than a time of 5:30 PM. But if the time really is 5:30 PM then it is the more accurate time. As the results of the two models diverge beyond their margin of errors, we are less and less sure which is the more accurate. Fun time for astronomy 🙂

[@strawberryfields5074]

That's a bit nit picky don't you think

[@illogicmath]

That mischievous smile from Fraser when he answered that question from that Musk fanboy about why NASA doesn't wait for the Starship to be ready to go to Mars is priceless. Just like Fraser's stifled laughter when he explained how the lunar landing in 2026 would be using Starship

[@frasercain]

Hey, I'm just reporting the current plans. And as soon as they inevitably slip, I'll report that too.

[@rogerphelps9939]

Not 2026. we will be very lucky if it happpens before 2030 and it is highly likely that SLS will have been ditched.

[@illogicmath]

@frasercain Sure, Fraser, I know. I didn't mean to imply that you weren't doing your journalistic work as excellently as you always do. But you can't deny that there was a slightly wry thought in you regarding our fanboy's question

[@illogicmath]

@@rogerphelps9939 what about Elon's dreams? Snake oil? Trying to keep hype high so that money keeps coming in? What’s his true aim when he blatantly lies to all of us about the dates? Mind you, I’m not denying that he’s one of the greatest businessmen of all time.

[@illogicmath]

@@rogerphelps9939 I think NASA will find an alternative supplier for the lunar lander. Perhaps 2028 would be a reasonable date for the mission

[@antonnym214]

There is water in a much more convenient location than the poles. At the west end of Valles Marineris is a feature called Noctis Labyrinthus, which is in the heart of the Tharsus region. The coordinates are 7°S, 93°W. There is a relict water ice glacier there which holds 36 billion tons or 8.7 trillion gallons of H2O; slightly larger than Lake Meade at the Hoover Dam near Las Vegas, Nevada. The canyon is 4.35 miles deep, which provides twice the atmospheric pressure: 12.4 millibars, compared to 6.1 millibars at the datum level. The 3.75mi. high canyon walls provide good protection from cosmic and solar radiation. Noctis will enjoy a mild climate, as it is only 258 miles south of the equator.

[@McFugo]

The universe being finite is a really scary thought to me. Think: everything - reality itself - has a limit. I know it's ridiculously large, but it still gives me a faint feeling of suffocation...

[@richardreumerman5449]

Alaris was probably my favourite.

[@andyspoo2]

Question for you: Why is it that old pictures taken on Mars are quite red, and now modern photos show it in a more neutral color that looks more earth like?

[@MichielHollanders]

@@andyspoo2 it must have have been moving away from Earth at the time of the old photos? 😄

[@rogerphelps9939]

It is just a case of colour calibration. Todays probes generally have a colour chart with which the raw picture data can be adjusted tto account for the ambient lighting conditions.

[@christopherbrice5473]

⁠@@rogerphelps9939the ambient lighting conditions unique to the planet are all I care about as a casual observer. I don't want color correction to make it look like Los Angeles

[@MichielHollanders]

@@christopherbrice5473 I get that, but actually Los Angeles also has totally different colors in bright sunlight or during the golden hour. Our eyes recalibrate for that to some extent (or rather our visual cortex) and so do people in video editing / color grading by setting the white balance. I like the more natural look of recent pictures. I'm curious what the first people on Mars will make of the colors.

[@hermanrobak1285]

@@christopherbrice5473 Keep in mind that most colour images from Mars are in false colour, or simulated colour, to varying degrees. Most of the cameras on Martian orbiters, landers and rovers are not RGB cameras with Bayer filters, like the digital cameras we are used to. Some probe cameras are monochrome, with a set of narrow colour filters, for spectroscopy purposes. To take colour images, they have to take two or three images through different filters. Typically, none of the filters are of the RGB sort, so reconstructing "natural" looking colours will be a matter of educated guessing. We like our colour images to look quite like our eyes would see the scene. Astronomers have different priorities.

[@glike2]

I worked on X-37 for years and I don't even know other than "experiments...", but speculating is fun. Maybe some cool Star Wars tech like a space laser 😮 that can pew pew at stuff for the CIA or a fusion Propulsion system that comes back for return and teardown inspection

[@AcousticallyYours]

Interesting question concerning why there are no probes other than the polar lander, sent to the Martian poles. However, a more probing question (pardon the pun) might be; why haven’t we sent a number of probes into the Valles Marineris? It seems that there are endless possibilities there.

[@rogerphelps9939]

he problem with that is that the reentry trajectory has a very shallow profile. To get into Valles Marineris you need a pretty steep final descent to get in without hitting the surrounding terrain.

[@christopherbrice5473]

would it be so hard to just have a rover enter from one end and drive inside it? Is it like a huge drop off? No ramps or gentle slopes?

[@AcousticallyYours]

@@christopherbrice5473 Do you know how wide the Valles Marineris is?? While it looks like a narrow channel from space, it is in fact miles wide at its widest. There should be little issue with being able to make a precision landing with our current technology.

[@AcousticallyYours]

@@christopherbrice5473 Yes, that is not a practical solution because the depth is many kilometers deep.

[@snortworld]

Fraser, question: has there ever been any scientific ideas about the magnitude of the universe? we know how small matter might be, and how vastly large the universe might be, but could the magnitude of the universe be infinite?

[@billygoat520]

I believe wherever one is to be the center of this universe, maybe not for others.

[@Vulcano7965]

I wonder if Mars poles could not be considered a "training ground" for probes for later landings on icy moons of the gas giants. It's the nearest icy landscape in low atmopheric pressure conditions.

[@CAPSLOCKPUNDIT]

There are two equally terrifying possibilities: that the universe is finite, or infinite.

[@bf99ls]

While it might be finite at any one moment in frozen time (Plank time effectively), it is fair to assume that stars are being created all the time, possibly in galaxies too far away for us to observe: which also means it might be infinite. Eternal? That’s another question.

[@Jameson1776]

Thanks for the answer Fraser. I knew you had no inside info to share just wanted your thoughts. 🙏

[@gregkelly2145]

"All these worlds are yours except Europa. Attempt no landing there..."

[@DrDeuteron]

MPL, phoenix were NORTH pole of Mars. The northern hemisphere is flat and low (below "sea level"), and we need that extra air to stop. The southern hemisphere is high and bumpy, so not enough air, and no-where to put a huge landing ellipse (unlike MSL and Percy, these were unguided entry). Also: It is not suspected of crashing: it crashed, 100%. The report says the leg-deploy maneuver was a definite fail, but that is a 60m drop, there should be a carcass visible from MRO. It may have tried to land at 10 km, in which case it cratered at very high speed--this is my bet.

[@Joker.of.All.Trades]

I believe the universe is literally an astronomically huge sphere. Everything we observe from Galaxies to you blood cells are in the shape of a sphere (or sphere like, to inclide the peanut shape where 2 spheres collided) or some version of a circle, therefore I think the universe is just the next level of that.

[@michaelcox1071]

Re: SLS - "what else do you want?!" I want it done for a reasonable cost. The SLS is 70s tech at astronomical prices. We could have used Falcon Heavy for a tiny fraction of the SLS cost. Just the transporter cost like 2.8B dollars. And they had to make a second version! More billions! As a US taxpayer, I hate SLS, even though I want to see cities on the moon.

[@michaelcox1071]

Also, I noticed that your launch cost graphic didn't include SLS...

[@donaldscott3921]

The Mars Phoenix Lander landed at the edge of the Mars North Poles. Not ON the pole, but pretty clear.

[@benmulvey2704]

Glad to hear you be realistic about Starship It has a huge list of things to achieve before attempting a lunar landing, and is well behind schedule on its initial milestones. Not surprising, given who owns it, and their track record of over promising and under delivering.

[@rogerphelps9939]

Starliner is a taxi to near earth orbit, not a lunar lander. You mean starship.

[@benmulvey2704]

@@rogerphelps9939 thnx, edited that, you are correct.

[@GntlTch]

Right, as if the SLS hasn't got much more to do and at a much slower pace of progress. I guess you have been living under a rock and are ignorant of the over 300 Falcon landings, almost three dozen missions to the ISS, internet connectivity to almost any location on the planet, et al. Elon has a record of "optimistic" timelines, NOT of under delivering.

[@rogerphelps9939]

The thing is that SpaceX has a habit of getting there eventually.

[@alibaba855]

@benmulvey2704 Oct 15th you look like a big loser

[@sleepy_143]

Hi Mr. Cain. My name is Andrew Pokey and I've always wanted to ask, what happens to all of the specialty tools and power drills NASA has made over the decades and doesn't need anymore? Thanks!

[@bjornfeuerbacher5514]

"How old is the universe?": One should also mention that astronomers are able to measure the ages of stars, and these all are found to be at most around 13.5 billion years. Additionally, when one measures the ages of stars in far-away galaxies, which we see as they were in earlier times, one sees that these stars indeed are _younger_ by the corresponding amount of time.

[@geraldinefields1730]

Thank you.

[@habibv]

Ardena Hi Fraser, When we say the Big Bang was the beginning of the universe, how can we also say the universe might be infinite? How can something with a starting point be infinite? Logically, this doesn't seem to fit. Regards, Habib

[@kieranlangley3092]

Love your videos. Never stop please. I'll support you as long as you never use AI :) best wishes to you Fraser.

[@RandallSoong-pp7ih]

Thank you!

[@CyrilleParis]

The problem with Stalink and other constellations of this size is not astronomy : it's a HUGE CLIMATE AND ENVIRRONMENTAL threat. At the rythm we lauch rockets nowadays, the impact on the envornment is a drop in the ocean compared to other activities. With these constellations, we will multiply this by several thousands every 3 or 4 years. Three main consequences : 1- the CO2 emissions : and even with hydrogen-oxigen propultion, there will be CO2 producede by the construction of the whole thing, multiplied by thousands of times what it is now 2- water in the mesosphere : when you drop water vapor up to 50 km, it goes into the water cycle and it doesn't affect the average quatity of water in the atmosphere. After 50 km, the water stays there and acts as a greenhouse gas 3- dozens of thousands of these satelites will fall down each year and burn in the outer atmosphere, dispersing tons of nanoparticules of a lot of things. One of the worst is aluminium : bye-bye ozone layer! All that for you to be able to watch Porhub in 4K in the Sahara.

[@rogerphelps9939]

CO2 emissions from rocket launches are miniscule compared with those from generally burning fossil fuels. Suppopse there are 100 launches annually and each one uses 100 tons of fuel. Burning each ton might release 3 tons of CO2. That makes 30,000 tons of CO2 per annum. Humanity currently emits around 40 billion tons of CO2 annually. So regardless of the actual CO2 emissions from rocket launches they are negligible compared with the total. Above 50km, ultraviolet light from the sun dissociates water into hydrogen and oxygen so it is not going to hang around for long. As far as aluminium is concerned I bet nobody has done an estimate of the amount of aluminium delivered to the upper atmosphere by meteorites. It seems likely to me that it is going to be a lot more than from reentering starlink satellites. The big problem with Starlink is its impact on optical astronomy which is not good. I really doubt the business model of Starlink. On the ground high speed optical fibre networks are delivering bandwidths much greater than Starlink can for less money. Here in the UK even the most sparsely populated areas are being cabled up so the demand for Starlink is minimal. This will happen in most developed countries where people gravitate to cities. In other places such as sub Saharan Africa they just cannot afford it anyway. That leaves a few well off people living in remote areas, shipping and the military.

[@LG123ABC]

What would happen if we started building extremely large telescopes on the surface of the moon? Would that be beneficial? Could we get even better astronomical views? Also, could we use the moon as a launching place for future interplanetary/interstellar missions? Would the lower gravity of the moon make it easier to build and/or launch missions into deep space? Basically, I was wondering if the moon would make a good observation point or spaceport if we built a permanent base there.

[@Cosmo3038]

What if dark matter is just a universal gravitational field that interacts with itself and also interacts with normal matter through the hadron particle??

[@leuk2389]

Hey Fraser. I like to think I have a pretty good grasp of physics but there is one thing I simply cannot wrap my head around. How can there be an absolute speed limit (the speed of light) when velocity is relative and there is no absolute frame of 0 movement?

[@bjornfeuerbacher5514]

Not every velocity is relative. Light _always_ moves with light speed with respect to an observer (in General Relativity, a _comoving_ observer), so that speed _is_ absolute.

[@ajr993]

17:41 can you answer how using starship is not an insanely ridiculous plan? It's going to require like 10-15 refueling trips so it can make it to the moon. Moreover why would you send a giant spacecraft to the moon when you could send a miniature detachable lightweight craft like Apollo did? Please explain how using starship in this way is a remotely good idea

[@jeffbenton6183]

It's closer to being ready than an Apollo-style craft would be. Furthermore, any human lander system needs to do more work than the Apollo one did because Orion doesn't have as much delta-v as the Apollo CSM.

[@ajr993]

@@jeffbenton6183 No its not close to being ready whatsoever and the idea of using 10-15 refuelling trips is quite frankly preposterous. Regardless of whether any other craft is viable right now, starship is not suitable whatsoever. Using complex full cycle methane rockets on the moon and hoping that they restart after being in a vacuum for like a week is crazy. It makes 0 sense to send starship down to the moon weighing as much as it did. It would make far more sense to develop something completely new that's realistic than to invest in an idea that is DOA. I would rather restart with a different crazy idea like using nuclear thermal rockets, building a refuelling space station, building some kind of SSTO system--anything other than the inherently bad idea that is starship. There is no chance starship is making it to the moon anything in the next 10 years.

[@treefarm3288]

Its a funny idea that a new gigantic telescope is built one day and then we see darkness past the last galaxies. The finite universe. Best question. Thanks.

[@torquewrench1969]

Edora---Thoughts on the "Kessler Effect"?

[@TheAces1979]

Cartego - My thoughts on this one. There is no 'outside' to the universe. The universe IS outside. And that terrifies me.

[@Threedog1963]

Sounds like you are talking about the observable universe vs the possible infinite universe.

[@SnareGG]

Q: 'whats the distance limit on the supermassive black hole's gravity?' A: yes.

[@n6hpx]

also did the starliner 5 land in the ocean. would have been nice to see it land on a recovery barge

[@idodekkers9165]

hey Fraser talking about gravity, when trying to get to another star, will we need to "power" the spaceship up to the gravitational equilibrium point between the stars, or is getting a certain amount of distance from the sun enough to ignore the residual gravity?

[@bjornfeuerbacher5514]

You need enough velocity to reach that equilibrium point, you don't need to accelerate the whole way up to that point.

[@tjmcguire9417]

Fraser. I don't know your background or your bona fides. I have watched you for some time and see what you do. Excellent work. So. As a Frazer myself, I am going to help fund you. Not sure how that's done because I never di this) but I will figure it out. Cheers laddie.

[@frasercain]

Thanks, my background is that I've been a space and astronomy journalist for 25 years.

[@nerufer]

[Cartego] follow up question; if one would shoot out a photon into space and it would never collide or be absorbed by anything, does it slow down? Or maybe a better way of putting it, does it lose its energy eventually? In other words, does it die out and fade into nothingness? Wouldn't that tell you that the universe is finate? About the europa clipper question also a follow-up: if we can unequivocally say, there is no life in the liquid water of europa, could we then definately say that sun-light is essential for the origin of life?

[@frasercain]

Nope, it keeps going forever

[@Goatcha_M]

Starship needs to launch 18-40 times with fuel caches before it can even reach The Moon, let alone Mars. The Saturn V's were more practical and the SLS is in that tradition, single launch.

[@Anziilife]

Is there a chance that what we see as the observable universe and CRB is simply the local bubble that started as a hypersized black hole that exhausted all its material and when it ran out of energy, it flipped into white hole/big bang, but it's just a tiny, local bubble in the huge sea of similar bubbles of existence?

[@Nolan1410]

Belsa, how would starship even implement a quick escape launch vehicle like dragon?

[@shadowbanned9680]

Question: Have astronomers ever discovered a previously unknown object close to the sun during a solar eclipse? (Comet, asteroid, etc.) And, do space telescopes now make ground-based solar eclipse viewing obsolete (for scientific discovery)?

[@BabyMakR]

Voting for Chulak

[@Quickcat21MK]

I think we should manufacture a 150 meter telescope on the moon. I know, its a mega project. And the moon has lots of hazards. But it would be really really cool. Could be done in 20 years if we tried. Maybe more.

[@jc441-i3q]

A visible light telescope? I don't think we could make a movable telescope that large even here on Earth. A smaller radio telescope on the far side on the moon would be really useful though. It's the only place where all artificial radio waves from Earth could be completely blocked.

[@FloridaManMatty]

Better yet, send multiple smaller devices that are spread out over multiple kilometers and have an operational lunar interferometer instead. No need to make a 150m telescope when you could literally have a 1500m or even a 15km system. The technology absolutely exists and is almost sort of “average” already. It would require multiple trips and plenty of preparation before, but it IS possible with stuff that already exists.

[@Quickcat21MK]

@@jc441-i3q If I had to make a choice. I would say whatever is optimal to get images of planets. It would be amazing, even if it was IR or some other type.

[@Quickcat21MK]

@@FloridaManMatty Or this.

[@bobinthewest8559]

@@jc441-i3q… Everyone mentions the “frequency clean” environment on the far side of the moon… But won’t that cease to be true once we begin putting infrastructure in place there? Wouldn’t every bit of communication hardware have to be connected by cables to prevent that ambient noise from developing?

[@LoadedSpatula]

I have a question that keeps buzzing around in my head: if our super massive black hole, Sag A*, got ignited into a quasar would our solar system be ok, given how far from the center of the Milky Way it is? I know that the jets of radiation that come out of the poles of the black whole are devastating to anything in its path, but what about the things to the side? Would it be like what happens when a bullet is fired out of a gun? Just a shock wave that comes out of the metaphorical barrel that gets less intense the further out it goes?

[@HPA97]

Hi Fraser! What would happen if the Andromeda galaxy suddenly disappeared, like in terms of gravitational influence? And how much would our solar system change/deviate compared to Andromeda galaxy still existing over large time scales?

[@ZachariahJ]

I knew those swarm satellites would be a problem! But when I mentioned it a few months ago, you shrugged it off - even went to the trouble of replying to my dumb comment to shrug it off! I feel totally vindicated. (Which doesn't happen often - I generally have no idea what I'm talking about). ;-)

[@rabindramishra00]

Hi Fraser! Saw this video and a question popped into my head! Is it possible some cosmic event causes a pocket of dust and gas to accrete directly into a Black hole? Aka scenario where gravity keeps winning against any outside pressure from accretion heat, fusion, electron degeneracy or neutron degeneracy all the way to complete collapse? Stellar fusion never gets a chance to blow material out? Would this explain Intermediate Black Holes? Has anything like this ever been detected?

[@IMB9000]

Hi Fraser, we hear that the universe is either infinite and goes on for ever, or finite and wraps around itself. But why can't it be finite with physical "borders" too far away for us to see ?

[@frasercain]

Sure, it could be finite but have a volume 1000x the observable universe

[@craigcollings986]

Hi Fraser With multiple telescopes using optical interferometry and separated by distances of many meters, how do they combine the receiving light when it comes from an angle closer to the horizon, so that the wave front is still combined? Is there an optical delay for the telescopes closer to the source?

[@bradymyers851]

Hey! Thanks Fraser! You're very cool! :))

[@isaacplaysbass8568]

Thank you Fraser and crew!

[@mattwuk]

11:25 well that explains beer then.

[@tuckfeem0834]

Hi Fraser! If there is so much outside the observable universe, could it be that some gravitational force (another bubble universe?) out there is causing the expansion and that dark energy is only having a somewhat local effect?

[@apocraphontripp4728]

Hey, I have a question. In our universe maps, do they account for the distance? For example, we know where we are right now, but do we know where a galaxy a billion LY away is right now? It's not where we see it is. If they don't, then our map of the universe is horribly wrong. Things are closer or further than they appear.

[@charlescouncill]

Nicknamed the “Stay Away Or Be Lunch” treaty, govts with space faring capabilities agreed to respect the privacy of Martians, Lizard People, and the Alliance and to declare the poles as “no fly zones”.

[@ezpzenterprisesllctennesse4443]

Are there manufacturing issues with the next SLS component?

[@fuegofool]

But would it wash away the rain? 12:46

[@joshm3008]

Hi Fraser hope you're doing well

[@Jedward108]

Given the long time frame of exploratory missions such as Europa Clipper, and the uncertainty of political stability, do any space agencies include contingency plans in case no one were available on earth to receive transmissions?

[@efxnews4776]

In the equatorial region of Mars temperatures can reach 21⁰C, during the martian summer, room temperature to humans. In Martian poles teperatures are way too cold even to machines operate.

[@bilthon]

You say it's "better to remain flexible" just because you're not footing the bill. The incredible costs SLS has had definitely means resources were deviated from other places where it would have potentially being used more productively. And sure, Starship is not ready, but it's moving faster and seems on the right track to be a more efficient alternative to SLS. So the question is at what point does that become clear to everyone and SLS is allowed to finally die?

[@nias2631]

I'd love to see Musk sink his personal billions into his dream goal and save the tax payers the costs completely. He lost billions on Twitter. He should do it for his ultimate dream.

[@nias2631]

Musk can pay for it out of his own pocket. He should do that.

[@frasercain]

Whenever Congress makes the decision and pulls the plug. Right now, it's the law that NASA must implement the plan as defined by Congress.

[@alexisdespland4939]

what do you think about item im-1 can you cover when they go back to the bottom of the pacific to get more of this interstellar object.

[@BOORHA1]

@frasercain Why is it that we see the same constellations throughout the year? Should we not be seeing different stars between summer and winter?

[@aalhard]

12:36 I think he meant, where does Sagittarius A become gravitationally dominant?

[@CoreyKearney]

The smarter question would have been what is practical limit of the influence our black hole, but that's not what they asked was it.

[@PitchWheel]

Can we say that the galaxy is the accretion disk of the central black hole? Thank you

[@dm1045]

You may have answered this before, but in what direction from us did the Big Bang happen? Secondarily- you discussed the expansion of the universe and that everything is moving away from us - but isn’t there a direction from the center we are moving?

[@bjornfeuerbacher5514]

The universe has no center. The Big Bang happened at every point of the universe at once. It was _not_ an explosion happened at a point _inside_ of space, but the appearance and expansion of space itself. Picture a balloon which initially is a single point, which expands to a sphere. The _surface_ of the balloon, i. e. the sphere, represents the universe, all of space. (If the universe is closed and finite - that's far from certain.)

[@frasercain]

It's happening everywhere. Every part of space is moving away from every other place. So everywhere is the center and nowhere is.

[@Tanks_In_Space]

Yeah, this AI tech is weird. I've noticed that KZbin has been flooded with AI-generated videos lately on topics like the military or the war in Ukraine. It won't be long before we can't tell if a Q&A like this was made by a real person or a PC. ( btw, this was my first ever FC Q&A and it got me glued to the couch, even though I already knew all of the answers.😊👍 )

[@randolphcordell6380]

Hi Fraser. Been on your radar since way back. There is no way gravity moves at the speed of light. If so the sun would lose track of the earth or vise versa and the earth would spin off into the void. It's time we dumped gravity as the.main force in the universe for the electric one which makes sense.

[@frasercain]

The kilonova in 2017 showed that they move at the same speed. We saw the radiation from the explosion at the same time we detected the gravitational waves

[@randolphcordell6380]

@@frasercain I replied to this but the reply is missing. I will see if I can tack it back on here. From what I read about the Kilonova the XRays were not detected until later due to the angle they travelled. So is there a reference that clearly states they were simultaneously? I do not find it. It was stated they coincided but not that they were synchronous.

[@randolphcordell6380]

Furthermore, the term "gravitational waves" indicates a known material or medium and for gravity we do not have that. We still don't even know what gravity really is.

[@marklapierre5629]

The X-37B is what the Space Shuttle would have been if it had not been designed by committee.

[@seangallagher779]

@@marklapierre5629 … a Senate committee, at that.

[@Phil_AKA_ThundyUK]

What are the implications of orbital refuelling on mission times to the outer solar system?

[@MildMaxUW]

If you could dig a hole right through the Earth and ignoring heat and pressure issues, what would happen if you jumped into it?

[@valaroma]

What is the earliest possible time that an alien civilization can arise since the birth of the universe? What would the CMB look like for them?

[@bobinthewest8559]

The only reference we really have for this… is the time it took for our solar system to “develop us”. So as of now, the best estimate is likely around 4 to 5 billion years (I’m not entirely certain of the age of our solar system).

[@valaroma]

@@bobinthewest8559 My comment goes behond our solar system. At what point in time there were enough elements to support carbon based life and technology somewhere in the universe after so many generations of stars cooking the ingredients for an advanced civilizaion. What would the CMB look like back then and what kind of information those aliens would extract from this?

[@bobinthewest8559]

It seems to me… All of the methods for deriving the “age of the universe”, rely on the concept of “rewinding the clock”, or “reversing the expansion”… which sounds all well and good… But, doesn’t this only apply to the “observable universe”? And if the observable universe is (let’s say) 93 billion light years across… wouldn’t that only reduce that volume down to a singularity/point, which would itself be at the center of a (then) observable universe of 93 billion light years across? Or, in other words… “rewinding the expansion”, would merely “draw in” a volume of space that we are currently unable to observe due to the current distance from our location.

[@Threedog1963]

If the universe is infinite, how would you know how old it is based on rate of expansion? You can only judge the expansion based on the observable universe, which could be only a tiny bubble of an infinite universe. I'd go as far as to say, in an infinite universe, the age of the universe is infinite and had no beginning.

[@random1511]

If there are primordial black holes, should we have already seen one exploding after radiating away all it's mass with hawking radiation?

[@randolphcordell6380]

If the zone where Europa exists is so radioactive (if that is the right term) what do we hope to find alive?

[@horizonbrave1533]

Question Fraser!! you always say that gravity/orbital assists from spacecraft etc, "steal" some of the velocity from the planet or body and convert it to energy that the space craft uses. Thus slowing down the planet or body every so slightly.... But doesn't the planet/body regain this 'stolen' momentum as it itself careens around the sun? (thus 'stealing' some of the sun's velcocity from it, to get the planet/body back up to it's 'recovered' normal velocity? And then in turn doesn't the sun 'steal' some velcoity from it's own orbit? So shouldn't these gravity assists equal out to no loss given enough time?

[@kkgt6591]

Very interesting question 😊

[@ericsmith6394]

Orbits are trading energy all the time, but they can't create or destroy it. You might end up with a system that looks the same within your best ability to measure it, but it is different. The Moon is a good example. Suppose you gave it a little spin. Over time it will tidally lock to Earth again. The spin momentum is transferred to Earth. It looks a lot like the Moon magicked it's way back to 'normal' but the combined momentum of the Earth and Moon still has the momentum you added when you spun the Moon. A lot of objects in the solar system are either locked to or in resonance with other things. A small push to one of them will slowly get shared with the rest. This won't put them back how they were, but it can preserve certain relationships like the Moon being tidally locked to Earth or the orbital resonance between Jupiter's moons. Depends on whether the resonance is stable or not.

[@arnelilleseter4755]

No. A planet doesn't just pop back to it's old trajectory. If it's orbit changes it stays that way until something else affects it.

[@horizonbrave1533]

@@arnelilleseter4755 I'm not talking about the trajectory, I'm talking about the rate at which it's moving.

[@arnelilleseter4755]

@@horizonbrave1533 It's the same thing. The orbit is directly related to the velocity. If you change the speed you change the orbit.

[@jasonsinn9237]

When do we launch an Enceladus Clipper?

[@spleefthedude7747]

If the father away the object the faster it’s moving away. Then the closer to our time we get the slower the universe is expanding. So. That means the universe expansion is slowing down over time not speeding up?

[@mattball2700]

If there was a big bang, wasn't the start a finite point? How could a finite universe become infinite?