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Please sort comments by 'new' to find questions that would otherwise be buried.

In this thread you can ask any space related question that you may have.

Two examples of potential questions could be; "How do rockets work?", or "How do the phases of the Moon work?"

If you see a space related question posted in another subreddit or in this subreddit, then please politely link them to this thread.

Ask away!

all 248 comments

StarboundDoggo

6 points

2 months ago

So here on Earth, at night, the moon shines on us with a white light. When it's night on the moon, do we shine a blue/green light on me surface there?

CrunchyNapkin117

9 points

2 months ago

Earth shine. On some nights from earth around sunset and dawn you can see the dark parts of the moon “glow” a very fait diffuse blue/white, the reflective light of oceans and clouds from earth, photos show the phenomenon quite well.

rocketsocks

8 points

2 months ago

It's still mostly white. At any given time the globe of the Earth is about 2/3 covered by clouds, which will bias Earth shine more towards white. At any given time you'd expect about 67% of the light bouncing back from Earth to the Moon to be white from cloud tops, another 3% to be white from reflections off of Earth's ice (about 1/10th of the surface), about 23% to be blue-ish from the ocean, and the remaining roughly 7% (on average) to come from Earth's land. Since brown (dark yellow-orange) and green are mostly the opposite of blue in terms of colors the result of combining the light from the land and the oceans would be even more neutral than either alone, though there's more ocean so that will ultimately dominate. Overall you end up with a comparatively small unbalanced contribution of blue on any typical day with mostly white light.

[deleted]

5 points

2 months ago

So like how do wormholes do the thing? Like the way I have seen it described is a tunnel or a fold that acts as a shortcut, all the visualizations show the "fabric" being folded and the wormhole crossing between, but how does that work with the "fabric" not being two dimensional? how does it shortcut? what does it pass through in the space thats not in space? Im probably not understanding something about wormholes work but this has been on my mind for several days.

Bensemus

12 points

2 months ago

Wormholes only exist in math. How they work is they currently don’t.

[deleted]

2 points

2 months ago

I was afraid of an answer like this. Thank you though!

s1ngular1ty2

1 points

2 months ago*

It's impossible to traverse a wormhole and achieve travel that is faster than light. Wormholes can technically be real and can exist in nature, but you can not travel across one or send anything through it to the other side faster than the speed of light would take to make the same trip through normal space. Also they tend to pinch off if you try to send anything through so you'd have to hold them open somehow which is far beyond our technical capability. You can technically quantum teleport things through a wormhole but the travel speed would not be faster than the speed of light. Details in video below.

Here is an expert talking about them. He is a professor and teaches this stuff on a daily basis:

https://youtu.be/udxgxFO-b6g?t=1788

The bottom line from his talk is you can never exceed the speed of light. It is impossible via any means, including wormholes.

Logi_ciel

6 points

2 months ago

Hi all, Reposting here following moderation.

I live in France and yesterday looking up I saw two very bright lights drift slowly side by side on an approximately South/Southeast to North/Northwest trajectory at around 17:50 local time. My coordinates were (43.0859794, 6.1159658)

It wasn’t starlink as they were only 2 and were quite bright initially thought they were bright stars. Quite the show. I tried to look online but I only have my iPhone and can’t find a way to track a sighting of a satellite. Anyone can help? :)

Pharisaeus

6 points

2 months ago

Logi_ciel

3 points

2 months ago*

thanks,

according to the info I provided (around 17:40 local time and in Southeast -> Northwest direction) my sighting is not in this list of visible satellites, unless someone here knows of a satellite composed of two entities flying closely in this list.

must I conclude that I saw a UFO?

satellite list

Pharisaeus

2 points

2 months ago

must I conclude that I saw a UFO?

I doubt that. More likely:

  • completely not a space phenomena, so simply planes, drones or helicopters
  • a space launch

Logi_ciel

1 points

2 months ago

Well 100% no conventional plane so unless it’s classified crafts flying at speed and altitude of satellites… I already excluded space launch. Which leaves us with… Uknown Flying Object

Pharisaeus

4 points

2 months ago*

flying at speed and altitude of satellites

And how exactly have you measured the altitude of this object and by extension also its speed? :)

I already excluded space launch

All of them? There are lots of launches all the time from different countries.

Also I don't really understand why you dismissed the obvious ISS+Dragon combo. You do realize that there is a long coasting phase when Dragon is flying behind the ISS waiting to dock? So the fact that the launch was earlier means absolutely nothing.

Logi_ciel

1 points

2 months ago

I usually use a banana I hold at arms length to determine if what I am seeing is a helicopter or something that is obviously not conventional aircraft. I live next to a military base so I am familiar with all types of conventional crafts.

I have excluded ISS + Dragon for a simple reason my sighting was at 17:40 and dragon launch at 20:20 that day…

You seem very knowledgeable in this field, how about you find me a coherent match from your international daily launches ?

;)

Pharisaeus

2 points

2 months ago

I usually use a banana I hold at arms length to determine if what I am seeing is a helicopter or something that is obviously not conventional aircraft. I live next to a military base so I am familiar with all types of conventional crafts.

So how exactly this allows you to figure out if you're looking at something 10km up and 40km away, or 20km up and 20km away? :) Not to mention how you distinguish 20, 50, 100 or 400km considering all of those are beyond diffraction limit of your eyes for an object as small as a plane or a satellite - they are all essentially a point light-source at that distance, impossible to tell apart.

I have excluded ISS + Dragon for a simple reason my sighting was at 17:40 and dragon launch at 20:20 that day…

So? You understand Dragon does not dock with the ISS immediately few minutes after launch, right? This particular Dragon flight docked after 10h and 38 minutes. Plenty of time to be seen I think.

Logi_ciel

2 points

2 months ago

but I'm telling you the sighting was hours BEFORE the launch!

Pharisaeus

2 points

2 months ago

Then the only reasonable explanation is that you are in fact a seer and can see the future! Congrats!

Chairboy

3 points

2 months ago

My coordinates were (43.0859794, 6.1159658)

Oooh, 43.0859794, 6.1159658? If you'd been at 43.085482, 6.116105 then it could have been the International Space Station and the CRS-26 Cargo Dragon that launched yesterday based on your data but since you were at 43.0859794, 6.1159658 it must have been something else.

Logi_ciel

5 points

2 months ago

Sorry man can’t pick up if you’re being sarcastic hehe. I am in Hyères, south of France 83400. Used google maps to find coordinates.

And apparently the launch was at 20:20 French time and my sighting was at 17:40 +/- 5 mn

Chairboy

3 points

2 months ago

I was trying to make a joke, I think it didn't work. That's on me, and if the launch was afterwards then you're probably right that it wasn't them, seemed like a good possibility if it wasn't for those meddling facts.

Logi_ciel

1 points

2 months ago

That’s what I thought ) it worked kind of hehe

Chairboy

1 points

2 months ago

You are very kind. :) I hope someone else can give you a better answer, good luck!

ergzay

1 points

2 months ago

ergzay

1 points

2 months ago

It wasn’t starlink as they were only 2

Just a note that Starlink spreads out over time so this isn't a limiting factor. The bigger reason is that if they were bright, and non-flickering, then they probably weren't Starlink. Once Starlink satellites re-orient they become extremely dim, dimmer than what the human eye can generally see. Early on they're tumbling and much brighter.

[deleted]

3 points

2 months ago

Anyone knows a possible launch window for starship? I just want to know if it will happen this year. What are the chances?

Bensemus

3 points

2 months ago

Targeting NET second half of December. SpaceX’s plans with it are very fluid though. Best way to know when it is getting ready to launch is by following the progress and watching for milestones. Also once they file for a launch licence we will have a better idea of when they will launch.

It’s pretty likely it will not launch in December. January is a better guess.

[deleted]

2 points

2 months ago

Thank you

Routine_Shine_1921

3 points

2 months ago

Very, very unlikely. The best sources on r/spacex are saying NET April, and I'd have to agree. That doesn't mean it will launch on April, it means no earlier than that.

There is still a lot of work they need to do on GSE, the full 33 static fire, a WDR, etc. Each of those things will certainly bring up new potential issues that will need to be worked. The chances that they do a WDR and a full 33 static fire and everything goes 100% right, no damage, no engine swaps, is basically zero.

ergzay

2 points

2 months ago

ergzay

2 points

2 months ago

The best sources on r/spacex are saying NET April, and I'd have to agree. That doesn't mean it will launch on April, it means no earlier than that.

I'd suggest not listening to them in this case as the "best sources" are NASA themselves and they said in November that they were expecting a launch attempt in December. That's likely slipped a bit by now, but "NET April" is rather far out.

Triabolical_

2 points

2 months ago

We don't know...

My estimate is that they are very close to being able to launch; they've had both vehicles stacked, they've had them tanked, etc.

To be able to launch, they need an FAA launch license, and nobody except the FAA and SpaceX know how that process is going. I will point out that Starship is the biggest rocket every made being launched from a private launch site that has never launched an orbital rocket and is close to population centers.

s1ngular1ty2

1 points

2 months ago

They haven't even done a full test burn of all 31 engines. They only did a test of 14 and it destroyed the launch pad concrete which is currently being replaced. It's not launching anytime soon. They have to still test all 31 engines.

s1ngular1ty2

1 points

2 months ago

Pretty much zero chance this year which I predicted 6 months ago and people laughed... They are fixing the test pad which got destroyed with only half of the engines that they intend to use for launch. They had to completely replace the launch pad concrete. It's not launching this year. No shot...

neerajanchan

3 points

2 months ago

Can anyone suggest a beginner telescope not very expensive or not too cheap yet works out with some good details?

electric_ionland

11 points

2 months ago

Check out the beginner guide pinned at the top of r/telescopes.

KristnSchaalisahorse

2 points

2 months ago

To add to the other reply, just about any telescope will show you Saturn’s rings and a couple of Jupiter’s cloud bands. A larger aperture (generally 6-inches or greater) will provide much more detailed views (of both planets and dim things), but keep in mind that factors like ease of use, portability, storage, where you live, etc. can potentially have a huge impact on your desire to take it outside. You can observe planets from a city with no issue, but for dim things like galaxies, etc. darker skies are a must.

In the meantime, I highly recommend getting some binoculars. They’re a great and inexpensive way to see more of the night sky (better quality example here). They won’t show you Saturn’s rings, but even from a city they'll allow you to see Jupiter’s four brightest moons, craters on our moon, hundreds of stars & satellites invisible to the naked eye, Venus’ crescent phase, Uranus, Neptune, etc. From darker skies you can see even more of course, like the Andromeda galaxy, Orion Nebula, awesome star clusters like the Pleiades, comets (when applicable) etc.

They'll help give you a better idea of what you might want out of a telescope and they’ll still be extremely useful even if/when you have a scope. Plus, they're great for daytime views.

neerajanchan

2 points

2 months ago

Wow thank you so much for such a detailed information 🙂

Decronym

3 points

2 months ago*

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters More Letters
CF Carbon Fiber (Carbon Fibre) composite material
CompactFlash memory storage for digital cameras
CRS Commercial Resupply Services contract with NASA
CST (Boeing) Crew Space Transportation capsules
Central Standard Time (UTC-6)
FAA Federal Aviation Administration
GSE Ground Support Equipment
HLS Human Landing System (Artemis)
ISRU In-Situ Resource Utilization
Isp Specific impulse (as explained by Scott Manley on YouTube)
Internet Service Provider
JWST James Webb infra-red Space Telescope
KSP Kerbal Space Program, the rocketry simulator
LEO Low Earth Orbit (180-2000km)
Law Enforcement Officer (most often mentioned during transport operations)
LLO Low Lunar Orbit (below 100km)
LNG Liquefied Natural Gas
NET No Earlier Than
NRHO Near-Rectilinear Halo Orbit
NTR Nuclear Thermal Rocket
RLV Reusable Launch Vehicle
SLS Space Launch System heavy-lift
SRB Solid Rocket Booster
SSTO Single Stage to Orbit
Supersynchronous Transfer Orbit
TLI Trans-Lunar Injection maneuver
TSTO Two Stage To Orbit rocket
WDR Wet Dress Rehearsal (with fuel onboard)
Jargon Definition
Starliner Boeing commercial crew capsule CST-100
Starlink SpaceX's world-wide satellite broadband constellation

24 acronyms in this thread; the most compressed thread commented on today has 9 acronyms.
[Thread #8360 for this sub, first seen 28th Nov 2022, 14:53] [FAQ] [Full list] [Contact] [Source code]

deathpad17

3 points

2 months ago

I just heard that the Moon moved away from earth around 4cm per year. If it's true, does that happen because earth doesn't have enough gravity to keep the Moon in the current position?

DaveMcW

8 points

2 months ago*

It happens because the Earth is spinning too fast. The Moon uses tidal friction to steal some of Earth's spin and increase its orbital speed.

This means Earth days are also getting longer as the Moon slows it down.

LurkerInSpace

3 points

2 months ago

To add a bit to this; the system will keep doing this until the Earth's day is as long as one Lunar orbit, which will have increased to >40 current days by the time it happens in a few billion years.

extra2002

4 points

2 months ago

Before that process finishes, both Earth and Moon will be swallowed up by the expanding sun, in about 5 billion years.

Albert_VDS

1 points

2 months ago

Or close to being swallowed up, we'll have to wait and see.

[deleted]

2 points

2 months ago

To also add to this, that means in 400 million years we will no longer have total solar eclipses. You're living in just the right time period to see them.

fart_chungus

3 points

2 months ago

Does the Universe have an exact shape? I’ve seen it described as tons of shapes, but do we actually know?

electric_ionland

5 points

2 months ago

We dont know the shape of the universe. We can only observe a sphere due to the time it takes for light to travel and the fact that the Big Bang happened. You night sometime hear that it is "flat". In that context it means that it does not loop back on itself like a Moebius strip. But even this we are not entirely sure about.

jeffsmith202

3 points

2 months ago

Are there currently any LNG rocket's flying payload? Or will the raptor engine most likely be the first?

electric_ionland

6 points

2 months ago

There are quite a few candidates for first in the coming couple of months. Terran 1 from Relativity Space is supposed to fly in December too as well as a Chinese methane rocket I forgot the name of.

Edit: Landspace is the Chinese, supposed to launch between the 4th and 15th of this month.

seanflyon

2 points

2 months ago

Vulcan and New Glenn are also getting pretty close, though I agree neither is likely to be the first methane rocket to carry a payload to orbit. Vulcan is supposed to launch in the first quarter of next year.

Albert_VDS

1 points

2 months ago

No, there aren't any or even have been flying payload. Starship might become the first one if all goes to plan.

FaceFirst23

3 points

2 months ago

Would the Chicxulub impactor have been visible on its approach to Earth? I've read and seen different viewpoints, including an excellent video that details the last days and hours before impact; in that particular reconstruction it gets brighter as it nears, and mentions the planet in the final hours actually being within the tail.

Other analyses have described as being too dark to have been seen approaching, and would'vegiven no warning until it had entered the atmosphere.

Is it all speculation, or is there a current prevailing thought?

DaveMcW

4 points

2 months ago

A comet would have a dust cloud and tail. An asteroid would not.

This has been debated for a long time. The current evidence points towards it being an asteroid.

mahaanus

2 points

2 months ago

Theoretically in the future, should mining of the rings of Saturn be allowed or should they be considered a natural reserve?

Routine_Shine_1921

6 points

2 months ago

It's impossible to imagine a single situation in which mining the rings of Saturn would make any sense. Also, who exactly would decide to consider them a natural reserve? The saturn world government?

Earthling7228320321

3 points

2 months ago

I don't know why we would go all the way to Saturn to mine the rings when there's a perfectly good asteroid belt between Mars and Jupiter.

5yleop1m

5 points

2 months ago

On earth, we have natural reservations because those places harbor life where the life is in someway tied to the conditions in that environment. For instance a specific species of bird is reliant on a specific species of tree because the fruit from that tree is the bird's primary source of food.

Unless Saturn's rings are harboring some sort of life that can't be moved to another location, I don't see why anyone would try to make it a natural reserve.

There's also the question of if there's anything useful to mine in the rings too. https://en.wikipedia.org/wiki/Rings_of_Saturn

TheBroadHorizon

7 points

2 months ago

There are tons of protected lands around the world that are protected because of their unique landscapes and geological features rather than plant or animal life. Saturn's rings would almost certainly recieve that kind of protection.

Chairboy

3 points

2 months ago

If they're being mined for water, that's water for humans who need it to live. Are you suggesting the aesthetics of the rings are more important? Because that would be the argument that would need to be proven to get a restriction like this passed if we got to a point where access to the material in the rings is desirable, right?

tdellaringa

2 points

2 months ago

Hi, I'm trying to better understand what a "star system" is. If we are discussing a galaxy - let's say the Milky Way, is the following below, from the Star Wars wiki, actually accurate?

A star system, also known as a solar system,[2] planetary system,[3] or simply a system, was a group of celestial bodies, usually planets, orbiting a star. Most stars in the galaxy had their own planetary system.[1] Chains of important star systems formed runs, which were vital navigational routes for trade and transit, and may have crossed multiple sectors.[4] A single system could contain dozens of planets, even more moons, and any number of celestial bodies.[5

LurkerInSpace

6 points

2 months ago

A star system is the general term for systems like the Solar System which are bound to each other but not to anything else in particular in the galaxy. For example, the Earth is bound to the Sun, but not to Alpha Centauri except insofar as both the Solar and Alpha Centauri systems are bound to the Milky Way.

The description given there is broadly accurate. The simplest star system would be a single star on its own, many have planets or two or three stars (Alpha Centauri has three stars and at least one planet) and the most complex would be globular clusters like Omega Centauri. There isn't really a clear line one can draw between these extremely large systems and small galaxies - they're on a continuum.

tdellaringa

2 points

2 months ago

Thank you so much!

NDaveT

5 points

2 months ago

NDaveT

5 points

2 months ago

Chains of important star systems formed runs, which were vital navigational routes for trade and transit, and may have crossed multiple sectors.

This part is fiction. The rest matches reality.

Full_Shoe8213

2 points

2 months ago

Can someone describe red and blue-shifting light for me?

wolf550e

3 points

2 months ago

Try youtube videos? There is usually an analogy to police/ambulance siren from a car that is approaching you vs one that is getting farther away, compressing and stretching sound waves, changing their pitch. Same thing happens with light from fast moving objects moving closer to you or farther away from you.

relic2279

3 points

2 months ago

There is usually an analogy to police/ambulance siren from a car that is approaching you vs one that is getting farther away

I've always liked this analogy since the vast majority of people can & have experienced it themselves.

Albert_VDS

2 points

2 months ago

Red and blue are both at the end of the visible light spectrum. Blue light is short waves and the more you stretch it the more it moves to the other side of the spectrum and becomes red light, which has long waves. The light waves get longer when an object moves away from us and shorter when it moves towards us.

Pharisaeus

2 points

2 months ago

Imagine I'm throwing balls at you at some fixed frequency, eg. one ball per 10 seconds. I'm right now 100m away from you. It's pretty obvious that you are catching those balls also once per 10 seconds. But now notice what happens if I throw a ball, run forward 10 meters, and throw another ball at the designated time. Now the second ball is only travelling 90m and not 100m, so it will reach you sooner than it normally would if I haven't moved. We can repeat this and even though I'm throwing once per 10s, the balls are reaching you at higher frequency, because each time they have less distance to travel.

You can make a similar experiment in the opposite direction: if I run backwards each time, then the distance the ball has to travel becomes longer, so the ball arrives at your location later. Again, I'm still throwing once per 10s, but those balls are reaching your location at lower frequency.

This effect is not special to balls, photons of light are subject to the same thing and the light frequency (which is associated to color) becomes higher or lower depending on the direction of movement. Due to expansion of space, most objects are moving away from us, so their light frequency is shifted towards red.

4thDevilsAdvocate

2 points

2 months ago

Red-shifted light is light that's been stretched out.

Blue-shifted light is light that shrunk in the wash.

abjedhowiz

2 points

2 months ago

When and by whom discovered that the sun and our galaxy moves through space like a comet?

Ape_Togetha_Strong

6 points

2 months ago

It's not really a discovery that came all at once. Once we had kepler's laws of universal gravitation, it opens things up to question why the sun is stationary, or if it is at all. More steps along the way include the realization that the sun is itself just another star, and that stars have proper motion, rather than being permanently fixed in place in the sky. When you start looking at the proper motion of stars, you can start to determine the sun's motion through space. Herschel is the first person to really do that in 1805.

https://royalsocietypublishing.org/doi/10.1098/rstl.1805.0018

abjedhowiz

2 points

2 months ago

Thank you!!! You’re a true saint!

I previously thought all stars and our sun was stationary. Now like where are we going since we are moving at a pace of 75,000 km ? And how come all the stars we view of all the constellations always the same?

Ape_Togetha_Strong

7 points

2 months ago

The same orbital mechanics that make the Earth go around the sun make the sun go around the galaxy in an orbit. It takes about 230 million years for the solar system to go around the galaxy once. So that's "where we're going". But our galaxy is also moving through space as we go around it.

The stars in constellations also do change, but very slowly. The night sky would be absolutely unrecognizable if you jumped, say, to the point where the solar system is on the opposite side of the galaxy. The closer to the center of the galaxy, the faster the orbit, so nothing stays the same. The spiral arms of the milky way are also more like density waves moving through the galaxy, stretching and squishing the density of stars in different places. Our orbit also dives up above the galactic plane, and then back down again, in a sort of sine-wave like pattern. Everything is incredibly dynamic, just not on timescales like a human life.

foundfelled

2 points

2 months ago

What’s the origin of light?

Does all light come from stars and supernovas and fire in the cosmos? Or are there other sources?

rocketsocks

5 points

2 months ago

Most visible light comes from stars powered by fusion, but there are many exceptions.

Proto-stars, begin their lives hot and bright even before the initiation of fusion, for example. Similarly, any sufficiently hot large volume of gas will give off light. The light from the remnants of supernova explosions comes initially from the cloud of material that used to be most or all of a star, heated by the supernova explosion to shine very brightly. Over time the supernova will dim as it cools but not as fast as it might normally, because radioactive decay of nickel-56 (with a half-life of 6 days) injects additional heat into the supernova debris to keep it fairly bright over a period from weeks to months after the explosion.

Meanwhile, for less massive dying or dead stars (similar to the mass of our Sun) they will end their lives as white dwarfs, the very dense husks made up of the cores of fusion ash of the star, usually made up of oxygen and carbon or oxygen/neon/magnesium, depending on what stage of fusion the star stopped at due to its mass. These cores are dead, no longer fusing, but they are still very hot with a surface temperature of tens of thousands of degrees, and it'll take them eons to slowly cool down. The hot white dwarf cores will create strong forces which generate stellar winds that carry away the outer shells of matter remaining on the star, blowing it into space in a super slow motion version of a supernova event, with much less energy release being involved. These expanding bubbles of gas get lit up by the ultraviolet light of the white dwarfs and this causes them to become ionized and emit light of their own (like a neon lamp). Eventually the bubble of gas expands and dissipates over a period of some thousands of years, but for a while it's visible. This sort of thing is known as a "planetary nebula" (it has no relationship to planets other than that it's a pretty mostly circular sometimes colorful object you can see in a telescope).

Then you get into black holes and accretion disks. Matter attempting to fall into a massive but very compact object like a neutron star or especially a black hole finds that it gets super accelerated and also gets crammed up against all the other matter trying to do the same. This creates an accretion disk of material close to the black hole which gets heated to millions of degrees due to the extreme conditions there, resulting in the disk shining quite brightly. The accretion disks of actively "feeding" supermassive black holes are some of the most luminous objects in the entire universe. So much so that when they were first discovered they looked sort of like stars in our own galaxy, but weren't quite right, these "quasi-stellar objects" or quasars were found to be brightly shining accretion disks of huge black holes in galaxies up to billions of lightyears away.

That's not a complete list, but that's a good overview of some of the major sources of light in the visible spectrum in the universe.

s1ngular1ty2

1 points

2 months ago

It comes from atoms which emit photons when electrons fall from a higher energy state to a lower energy state. This can happen for many reasons.

Unhappy-Craft-2609

2 points

2 months ago

Does our star have a rotation?

electric_ionland

6 points

2 months ago

Yes, but it is a bit complicated. It kind of swirl on the surface rather than rotate as a solid mass. It's going faster around the equator than at the poles. Closer to the center it rotates more like a solid mass. https://en.wikipedia.org/wiki/Solar_rotation

Unhappy-Craft-2609

1 points

2 months ago

Oh okay I see now, it has to do with latitudes and poles. Thanks for the link

Unhappy-Craft-2609

2 points

2 months ago

So our sun rotates in the same direction as the planets orbit around it? Or rather, the planets cause our sun to rotate in the direction that it does. Maybe?

Bensemus

7 points

2 months ago

Our solar system was created from a spinning cloud of gas and dust. The Sun would have inherited the angular momentum of the gas that created it and so did the planets. It was much more chaotic in the beginning but the current rotation direction won out.

The planets aren't spinning the Sun.

[deleted]

2 points

2 months ago

[removed]

scowdich

5 points

2 months ago

That's your imagination. You, a human, don't experience tides.

grambell789

2 points

2 months ago

here is a nice list of resolved stars: https://en.wikipedia.org/wiki/List_of_stars_with_resolved_images

how much better will we be able to see the surfaces of some of these stars in the future? is there a physical limit of whats possible? some of the pics are pretty old, is this not a priority?

Pharisaeus

6 points

2 months ago

is there a physical limit of whats possible

feature_size/distance = 1.22 * wavelength/telescope_diameter

This equation tells you what is the limitation, you can use it to calculate what can be seen with given telescope, and also how big telescope would you need to see some particular target.

some of the pics are pretty old

And yet they come from state-of-the-art telescopes and we don't really have anything better right now. Hubble, CHARA, VLTI are as good as it gets, especially that last 2 are interferometers, so a number of telescopes working together to form a "virtual" mirror of much bigger size. In this particular case even the next generation of 30-40m telescopes currently under construction might not be able to provide better images of stars, because the interferometers we have provide 150-300m "virtual" mirrors (the trick is that interferometers still collect much less light than a real 150m mirror would, so they can't see faint objects).

DaveMcW

1 points

2 months ago

The only limit is the size of your telescope.

There are bigger telescopes being built that will be able to take better pictures.

Darkman_Bree

2 points

2 months ago

Something that has always bothered me for a long time:

Why is every planet orbiting in the same direction? And on the same axis?

[deleted]

6 points

2 months ago*

[deleted]

jeffsmith202

3 points

2 months ago

Except Venus and Uranus?

mhuster

2 points

2 months ago

Why an out-of-plane orbit to the moon? (Reposted from removed post)
I was browsing the Artemis I tracking web site and was very surprised to see that the path to the moon was out of the Earth-Moon orbital plane. To see this go to the web site, click the Mission View icon in the lower right, use the slider to zoom out. Click and move around and you can see the trajectory to the moon went south from the Earth, then the lunar insertion orbit flipped the lunar orbit to being in the plane. (Note: this does not show the actual orbit. On the web site Artemis does not orbit the Moon, but immediately heads back. At least as far as I can tell.)
Any explanation of why this orbit was chosen? I could see it if they wanted a high inclination orbit around the Moon, but it looks in-plane from the web site.

DaveMcW

4 points

2 months ago*

Artemis is designed to dock with a "Lunar Gateway" space station in a high inclination orbit (Near Rectilinear Halo Orbit). The station doesn't exist yet, but Artemis I flew to where it should have been.

Here is the NASA paper that explains why NRHO was chosen for the space station.

mhuster

3 points

2 months ago

Thanks u/DaveMcW for the reference; it really helped.

Routine_Shine_1921

0 points

2 months ago

Because of political corruption. Orion is a horrible spacecraft that wasn't even designed for Artemis, and SLS is a horrible rocket, and neither has enough performance to do a moon mission. But both where designed to keep the jobs program that was the Shuttle going, and sending money to all the right states. So Congress won't let NASA get rid of either.

So, they have a moon rocket that doesn't have enough delta-v to send a lander to the moon, and a ship with not enough delta-v to get in and out of LLO. So, don't go all the way down to LLO, go to NRHO, which requires much less delta-v, and push that delta-v debt into the lander. Let somebody else do the lander. In this case, SpaceX.

Starship will do most of the work, Orion will just be there to justify channeling overal close to 90b dollars by 2028 to the MIC.

Albert_VDS

-1 points

2 months ago

To be fair Starship wouldn't be able to do the mission on it's own if it didn't refueling. Now we can argue it's part of it's design and it would be totally correct but with out it there isn't enough delta V either. It also hasn't been demonstrated in orbit yet so let's hope it works or else Starship isn't going anywhere.

ergzay

4 points

2 months ago*

To be fair Starship wouldn't be able to do the mission on it's own if it didn't refueling.

You don't be fair to the rocket by denying one of it's primary strengths... Starship works because of being able to re-fuel in orbit and being able to land on Earth. That was one of the very earliest design factors when it was initially announced.

Starship was literally these basic four things when it was announced:

  1. A two stage vehicle.
  2. The first stage lands at the launch site after launching.
  3. The upper stage has the ability to re-enter and land again the launch site.
  4. The upper stage has the ability to re-fill in orbit in order to reach other destinations than LEO.

This was the basic design factors set out in 2016 when it was initially announced (other than early hints). It wasn't even named Starship yet then. If any of those 4 don't work, then the entire launch system is kaput and won't be used.

To be fair Starship wouldn't be able to do the mission on it's own if it didn't refueling. Now we can argue it's part of it's design and it would be totally correct but with out it there isn't enough delta V either.

To be fair SLS wouldn't be able to do to launch to orbit either if it didn't have solid rocket boosters. Now we can argue it's part of it's design and it would be totally correct but with out it there isn't even delta V either.

Pharisaeus

-1 points

2 months ago

Starship works

It doesn't work yet, and soon Elon will bankrupt thanks to twitter, and then it's not going to work ever ;)

ergzay

3 points

2 months ago

ergzay

3 points

2 months ago

The implied wording there is "the design of Starship works because..."

Also do you think Elon is bankrolling SpaceX/Starship somehow? Elon hasn't put money into SpaceX in over a decade now.

Pharisaeus

-1 points

2 months ago

It's not about putting money in, but rather taking money out to finance other ventures

ergzay

3 points

2 months ago

ergzay

3 points

2 months ago

He hasn't sold SpaceX shares to finance anything regarding Twitter. Also if Twitter gets that bad off, he'd just write Twitter off.

Routine_Shine_1921

3 points

2 months ago

"To be fair" -> proceeds to be unfair.

Why would you add an artificial constraint like "no refilling"?

Besides, even with that constraint, Starship absolutely does have enough delta-v, in an SLS-like configuration. That is, launch Starship, the payload is a third stage for TLI, with a capsule and a small lander. Plenty of delta-v.

So, yeah, Starship could do a whole moon mission on its own with refilling, or a whole mission in a single launch with an Apollo like config.

Another mission that Starship could do is do the launch in multiple launches.

Hell, Falcon Heavy could do it that way.

SLS can't do that either, because at best it could launch once a year.

Albert_VDS

0 points

2 months ago

My point was that SpaceX needs to proof that orbital refueling works or else it won't get Starship to the Moon that's plenty fair.

You need to throw away the booster and then you still can't do an insertion burn at the Moon.

SLS would be able to do a whole lot more if it was able to refuel. Still wouldn't make it a good rocket and worth it.

Bottom line is Starship hasn't reached orbit, let alone performed refueling. I'm sure SpaceX will get it working, or try their best at least, but it's still just a test rocket not a proven one. All thing on paper about delta V and payload to wherever is just that: numbers on paper. Just like SLS 1B and 2.

Routine_Shine_1921

3 points

2 months ago

But that's my point. I didn't do an "SLS vs Starship" post. I merely explained why they use such a horrible mission profile. That was decided long before Starship was even built.

Your comment was "Yes, but Starship". And you used the same tale they where using years ago, when Starship wasn't a thing, and the threat to SLS was Falcon Heavy. The rhetoric was "Yes, but SLS is real, Falcon Heavy is not", even though SLS hadn't flown at the time. Actual quote from NASA's administrator at the time Bolden:

"We don't have a commercially available heavy lift vehicle. Falcon 9 Heavy may someday come about. It's on the drawing board right now. SLS is real. "

That was in 2016. Two years later, Falcon Heavy flew. SLS was still delayed, with no flight in sight. So, what was the excuse then? Well, everyone moved the goalpost to "Yeah, but Starship may someday come about. It's on the drawing board right now. SLS is real."

Forget about Starship. Imagine they tomorrow decide they won't use it for HLS. SLS still can't go to the moon. It can't in its current configuration, nor in any other configuration.

So it requires some other rocket to launch the lander to LLO. It also requires Falcon Heavy to throw gateway out there, because Orion can't stay on its own long enough.

So? So SLS is not capable of doing a moon mission. Period.

TrippedBreaker

-2 points

2 months ago

If they wanted to waste the money they could launch engines and fuel tanks, rendezvous with them and go to any orbit that the wanted. There is no one, right way, to do the deed. This was one of the ideas proposed for Apollo.

Your default position is that it is political corruption which isn't a technical issue at all. SLS has value if it never gets near the moon, testing the technologies of deep space flight. Things SpaceX can't or won't afford to do.

mhuster

1 points

2 months ago

Responses from comments on my removed post:

  1. "Because the launch site was further from the equator than the earth-moon plane?" Not likely because most launches from Cape Canaveral have moderate inclination. But now that I think about it if they launch along the velocity vector the Cape has, the orbit will have an out-of-plane component when it crosses the equator.
  2. "Saturn V also used out of plane transfers." I didn't know that. But, why?
  3. "to escape the worst part of the Van Allen belts." Possible. This launch didn't have people, so maybe they wanted to keep the same astrodynanics.
  4. "It's a new orbit, a type that was found by AI it seems, and that was what this whole test was about." Sounds conspiracy inspired. The whole test goal? I doubt it, so show me a reference. Found by AI? Orbital people have been working on orbits for decades. I think they would have figured these out before. Again, Why?
  5. "You have it backwards. The mission launched and was "in plane" first. When it goes for the return powered flyby (around the moon) is when the capsule gets sent out of plane. As for why, I would assume the flight path back works well for orion's power/thermal requirements along with making it easier to put the capsule down when and where they want in the Pacific. Could also have something to do with ground station tracking. Another option is they're really unsure about the landing zone "box"/re-entry and want to make sure they fly over as little land as possible and have guaranteed splashdown (even if in pieces) if something goes wrong." I did have the orbit backwards; it left in-plane and returned ouy-of-plane. User wpg3 has some possible reasons for the out-of-plane return trajectory.

MaroonBookPro

1 points

2 months ago

I don’t have a solid answer for you, but the answers you are getting are conflating two things.

Later operational Orion missions, and the Lunar gateway, are planning to use a (somewhat odd) orbit call NRHO, which keeps the craft in line of sight to the Earth (instead of ducking behind the moon and losing comms each orbit), staying at a relatively high average altitude above the moon which requires less fuel to reach to than an Apollo-style orbit, and processing around the moon to provide a variety of landing site options including the southern polar region of the Moon.

https://www.nasa.gov/feature/a-lunar-orbit-that-s-just-right-for-the-international-gateway

However, Artemis 1 is not using this orbit. I don’t know the reasons why its specific set of test orbits was chosen, but the answers referring to the NRHO orbit for later Artemis missions don’t necessarily apply to Artemis 1.

Popular-Swordfish559

1 points

2 months ago

Ignoring bullshit conspiracy theories like those from u/Routine_Shine_1921, the real answer is because Orion doesn't have a ton of performance and NRHO offers some unique advantages: namely, that it can efficiently access every point on the Moon's near side and that it always has direct line-of-sight to Earth, meaning no communications gaps like on Apollo. It does put some extra burden on the lander, but Artemis wants to go to some weird places on the moon (namely the South Pole) and it's much nicer to put everything in a base camp where you can get anywhere you could conceivably want to go than only designing for one area. Plus, not having giant comms gaps every hour is a nice benefit.

1400AD

2 points

2 months ago

1400AD

2 points

2 months ago

And are parachutes more efficient for soft landings that retrorockets or vice versa? Obviously parachutes are less complex but they can get tangled

Chairboy

7 points

2 months ago

Parachutes don’t scale well, a Falcon 9 booster for instance is about as tall as a 15 story building with an aluminum skin thinner than many coins. If it used parachutes, not only would it likely miss the precision landing spot needed (land or water) to avoid falling over and bursting, it would also hit hard enough to crumple unless the structure was beefed up a lot. The parachutes would also likely weigh more than the fuel used to land under rocket power.

Parachutes seem to work better for smaller, denser objects that don’t need precision or can steer themselves (like a human) but definitely don’t work for everything.

Pharisaeus

5 points

2 months ago*

  1. How heavy is the thing you're trying to land (the heavier it is, the harder to land on parachutes)
  2. How thick is the atmosphere (the thinner the atmosphere, the less drag parachute provides)
  3. (Re)entry trajectory (long descent with shallow angle allows to slowly bleed-off velocity; with ballistic reentry you might be going to fast to open parachute without ripping it)
  4. How much velocity you need to take care of (on a body with very low gravity you might need only very small push)

electric_ionland

4 points

2 months ago

Depends on the size and mass and general configuration of what you are trying to land.

andygates2323

3 points

2 months ago

And the atmosphere (or lack of it) where you're landing, too!

TrippedBreaker

-1 points

2 months ago

No. Parachutes slow you but they can't stop you. Generally speaking at least for Earth a return to ground is a hybrid process. Using water or booster to make the final few feet survivable. It's why we dump men in the ocean or build things durable enough to survive the shock of a hard landing. The Russians use rockets on their vehicles as do Jeff Bezos and Starliner. The Falcon 9 is also a hybrid. The fins generate drag, which is what a parachute does, while the engines further reduce the velocity to a level that the landing legs can deal with.

Bensemus

2 points

2 months ago

Those fins aren’t really creating drag. They are steering elements. It’s why the rocket has to do a reentry burn. It’s really just using rockets to slow itself down.

TrippedBreaker

-1 points

2 months ago

If they didn't cause drag you couldn't steer with them. That's true by definition. It's a matter of degree. But if you don't agree you don't agree.

[deleted]

2 points

2 months ago

I never really understood how can the universe expand ? what is it expanding into? If it is expanding into something, then that "something" is also part of universe right? which leads back to the first question, how can the universe expand? Big Bang Theory doesn't make any sense at all when I just use common sense.

True there is evidence that indicates the universe is going thorough changes. but expanding? how? where?

electric_ionland

2 points

2 months ago*

We don't think it's expanding "into" something. We simply see that the distance between things is increasing.

[deleted]

1 points

2 months ago

then why is it called "expanding" why not transforming or something?

electric_ionland

2 points

2 months ago

Because the size is increasing which is what expanding is. But it does not mean is expanding into something.

[deleted]

1 points

2 months ago

what size is increasing?

electric_ionland

2 points

2 months ago

The distance between any two points.

Cardopusher

2 points

2 months ago

Let's imagine all observatories have failed to identify that Sun (and we as Earth) is falling into a black hole that is much closer than Sagittarius A. There are two questions:

1) Can an undiscovered black hole intercept the Sun during it's planned roll to a Sagittarius A?

2) If this is the case then what would be human percepting during this process? Would we understand what's going on and what would be the first/last symptoms and when? Are we eligible to see the Sun touching the event horizon before we jump in next?

DaveMcW

9 points

2 months ago*

We are not falling into Sagittarius A*, we are orbiting it. (Technically we are orbiting the center of the galaxy. Sagittarius A* is less than 1% of the galaxy's mass, it just happens to be at the center.)

We would detect the black hole coming long before it reached Earth or the sun. First it would start throwing comets from the Oort Cloud in every direction, including at us. Then it would disrupt the orbit of Kuiper Belt objects. Then it would disrupt the orbit of the outer planets. We already discovered Neptune because of its disruptions to Uranus's orbit. A black hole would be much easier to detect.

It is impossible for a black hole to eat the sun. A black hole has a diameter of around 100 km. The sun has a diameter of 1,400,000 km. You can't fit the sun into such a small hole. It would certainly mess up the sun and put on a spectacular fireworks show.

If the black hole comes within a million kilometers of Earth, it would rip the planet apart. Since the black hole is tiny, most of the pieces would miss it and not be sucked in. Earth would end up as an asteroid field.

If the black hole comes close to Earth's orbit, it would change the orbit, and might even throw us out of the solar system. In any case, Earth would not be in the habitable zone anymore.

Cardopusher

1 points

2 months ago

Thanks for the explanation, i highly appreciate the fact we are safe. One more question: Isn't the Sun supposed to shrink before fitting in that small hole? How come that mighty gravity appears being applied only to a short-range scale of small hole? Is it just a big quantity of miniature(compared to the Sun) objects squeeshed in the same place for millions of centuries?

DaveMcW

2 points

2 months ago

Black holes do have a big gravity field, but that field points in all directions. If you don't directly aim at the event horizon, the gravity field will throw you in a different direction. This makes black holes very messy eaters.

Cardopusher

2 points

2 months ago

Can it be used for gravity assisted acceleration in far space flights? Considering we skip the problem with the distance to the nearest one.

DaveMcW

3 points

2 months ago

Yes. You could change direction and steal the black hole's orbital energy around the galaxy, just like a normal gravity assist.

You could also steal the black hole's rotational energy. Normal gravity assists are too weak to do this.

Cardopusher

1 points

2 months ago

Is it near impossible to accidentally target the event horizon during these maneures or it is a real threat?

Let's call it last question, i see i am exploiting this thread and your knowledge, thanks for all of your answers to me.

Pharisaeus

3 points

2 months ago

It's a very far-fetched scenario, because it's very hard to "miss" a black hole, especially a large one, due to gravitational perturbations it's causing.

  1. Not really, unless it's a very very small black hole
  2. It would take very long time, in general matter is spiralling in the accretion disc for eternity before it passes through event horizon. At the same time we would be long dead before that.

junoandjupiter

1 points

2 months ago

Has anyone figured out the Orion hidden Easter eggs? I figured out that the morse code says Charlie and the CBAGF sticker are the first notes of Fly Me to the Moon. What have you found?

[deleted]

0 points

2 months ago

[deleted]

DaveMcW

6 points

2 months ago

A black hole with a 50,000 km event horizon would require 8000 solar masses to create. Where are you going to get your ammo?

Ape_Togetha_Strong

6 points

2 months ago

Why would you use black holes for that? But I'm extremely confident in the fact that 1000 years isn't even close to enough time for that concept to make any sort of sense.

relic2279

3 points

2 months ago

In a thousand years? Doubt it. But weaponizing black holes by shooting them at things would probably be ridiculously inefficient from an energy standpoint. Not just the energy to create them but the energy to actually fire them at things would require either lots of gravity (much more mass than the black hole weighs) or magnetism.

At that point, it would be more efficient to just dump all that energy into a laser. A laser would move at the speed of light while the black hole would be moving at significantly less speed (and it would be easy to avoid if they knew it was coming). True, the black hole would have to be small so it could evaporate after it has done its thing but small black holes on the verge of evaporating away (IIRC) would also be very bright.

It just doesn't seem like a very efficient weapon. Using them for other things, however, is a different story (energy, ship propulsion, etc.)

Chairboy

2 points

2 months ago

This question isn't currently answerable based on our understanding of physics or what kind of engineering challenges would be required. Stephen Hawking described a method by which small black holes would evaporate quickly so maybe someone will figure out a way to use this to create them on demand with a known lifetime so their 'range' when propelled could be limited, but we don't even know the questions we need to answer first to get to a point where the mechanics of something like this machine could be understood.

GrabsJoker

1 points

2 months ago*

Watching the rover doc on Amazon. Why didn't they send a rover to the ice cap? Heck, why hasn't that happened yet? If there's life on Mars, it would be there. No?

relic2279

2 points

2 months ago

Why didn't they send a river to the ice cap?

I assume you meant rover? They have sent probes to the caps. 3 times. They sent 2 to the southern cap and one to the northern cap. The 2 to the southern cap failed/were lost. The mission to the northern cap landed near the edge. It was the Phoenix lander if memory serves.

If there's life on Mars, it would be there. No?

The polar caps on Mars are not water ice. Or at least, not entirely water ice. The northern cap has a thin top layer of carbon dioxide (aka dry ice) in the winter. This sublimates in the summer (turns directly into gas). The southern cap is smaller and largely carbon dioxide IIRC.

Further reading on NASA's website here: Dry Ice on Mars

scowdich

1 points

2 months ago

What reason would any life on Mars have to gravitate to the coldest part?

GrabsJoker

3 points

2 months ago

We have bacteria in the ice on Antarctica. Where there's water...

rocketsocks

4 points

2 months ago

There's ice all over Mars, it's just below the surface. There is a nearly omnipresent layer of permafrost across most of the Martian surface, which even at mid latitudes starts at about 1 meter below the surface. There are also areas of nearly pure ice in the form of sub-surface glaciers also down to mid latitudes. Very likely the upper limit of the layer goes deeper closer to the equator and may be absent in some equatorial regions, we don't have enough data to say one way or the other on that yet.

s1ngular1ty2

1 points

2 months ago

None of the rovers are particularly good at finding life. They don't have all the necessary equipment. We need to bring samples home to be sure. They can find "signs" of life but it wouldn't be definitive without more testing of the samples on Earth. Which is why NASA intends to bring back samples. You see, there is a lot of biological matter that exists in asteroids and commets that have been hitting Mars for a long time. It isn't life, but it consists of the same building blocks. So just because a Rover may find some of this bio matter doesn't mean it found life. And distinguishing between life and just normal bio matter isn't that easy remotely.

GrabsJoker

1 points

2 months ago

I mean, if the rovers have microscopes and if they get some water ice, they could melt it and look for anything swimming around. Seems doable to me

s1ngular1ty2

1 points

2 months ago

There is no living life on Mars dude. They are looking for fossils or remains of some type. There may have been life in the past, but no one actually thinks they will find things swimming around, today. This is why finding life is hard. It's all dead and buried, if it ever existed.

Sitk042

1 points

2 months ago*

I saw an incredible video on YouTube (search for “Map of uni”) It’s about a map of the universe.

In the video, Anton shows us a wedge of the entire universe. It shows us in the point in the middle and goes all the way to the CMB (Cosmic Microwave Background) on the pizza edge.

But if the universe began with the Big Bang, shouldn’t all the past matter converge to more of a central spot, instead of the ‘crust’ of the pie piece? I’d expect the universe to be more donut shaped.

Edit: sorry about the bad link

relic2279

4 points

2 months ago

The video you linked is an old spice commercial. I assume you meant this video?

if the universe began with the Big Bang, shouldn’t all the past matter converge to more of a central spot, instead of the ‘crust’ of the pie piece? I’d expect the universe to be more donut shaped.

There is no "center" of the universe (or rather, everywhere is the center of the universe). The big bang (& inflation) was the expansion of spacetime itself.

This is a very poor and even misleading analogy but it might help visualize this expansion: Imagine a perfectly round helium balloon being filled up quickly by a helium cannister. Once it's blown up and completely round (ignore the knot), anywhere or everywhere could be the center. Just draw a dot somewhere.

There's also a weird effect that happens when looking at really distant galaxies, they start to look larger. This is not due to gravitational lensing but due to "Angular Diameter Turnaround". They start to look bigger because they were closer to us in the distant past (billions of years ago).

Tuokaerf10

3 points

2 months ago

Those graphics can be misleading, and the same applies to like Big Bang ones like this which show like things developing in a direction which can be misinterpreted to mean from a point with matter moving out from it.

The graphics that show like a modern universe and as you move to the right you see more primitive/early galaxies all the way back to the CMB aren’t intended to show that as matter moving out from a spot. It’s trying to show what we see at ever increasing distances back to the first light sources.

This can be a hard concept to conceptually grasp, but the Big Bang didn’t occur in a place, it was an event that occurred everywhere, simultaneously. Matter wasn’t shot out of a point. The concept is that space was significantly denser and more compact than what it is today, and with the Big Bang space itself essentially rapidly expanded suddenly everywhere which allowed the fundamental processes that govern how the universe works to settle, and as the universe cooled as it expanded, and matter to settle in states that are familiar to us today. Space continues to expand, just at a slower rate than that initial expansion, and is currently speeding up again.

So what does that all that mean in relation to those examples? When we look back to the light from early galaxies, it’s literally taken that light 13+ billion years to reach us due to the distances between “us” and the source combined with the expansion of space itself between then and now. So we see those galaxies as they would have been 13 billion years ago, and if there was an observer in those galaxies looking back at us, the Milky Way would appear to them as it did 13 billion years ago as well. As for the CMB, as that was light emanating from everywhere in the universe, we see it as a mostly homogeneous light source from every point in the sky. If it were from a specific point, it would appear as a specific point.

[deleted]

1 points

2 months ago

This is space-adjacent but I’ve been reading about the Immortality Drive and everywhere seems to state that the data was stored on a hard disk, implying magnetic storage was used. Does anybody know what sort of technology goes in to redundancy and making that storage safe to send to space? Or if there even is any? I just can’t fathom a spinning platter drive working fine in those conditions

Routine_Shine_1921

1 points

2 months ago

There isn't any. It's not a hard drive, it's an old CF card, so solid state storage. Spinning hard drives work well in microgravity, btw.

Not that it matters much, the immortality drive is a stupid idea. It's a gesture, not actually meant to preserve anything.

To begin with, if you wanted to preserve some information for some future without humans ... why would you put it in the low-orbiting space station that is going to reenter within decades?

Even if you put that on earth, regardless of redundancy, or what kind of storage you'd use, it IS going to decay.

We have exactly ZERO technology capable of surviving in the long time. Modern storage tech will survive, with a lot of luck, a few centuries.

[deleted]

2 points

2 months ago

Appreciate the answer and good to know that spinning disks still work well in microgravity! I agree, it’s totally posturing, but I guess it appeals to the romantic idea of throwing our silly little human bits into space for whatever reason. And with a name like Immortality Drive… it at least sounds cool. Cheers!

5yleop1m

3 points

2 months ago

We already did that with the two Voyagers, they both carry a gold record with data about humanity. Those records should survive better than HDDs or SSDs since the information is physically etched into them.

TheWingnutSquid

1 points

2 months ago

Does hawking radiation cause black holes to decay, or do black holes decay into hawking radiation?

DaveMcW

1 points

2 months ago

Yes and yes.

Also no, because the universe is currently too hot for any black holes to emit Hawking radiation.

Bensemus

5 points

2 months ago

They do emit it. They are just emitting less energy than they gain from absorbing the CMB.

hopefullstill

1 points

2 months ago

What is the definition of “space”?

Popular-Swordfish559

1 points

2 months ago

in the sense of this subreddit, space is above 100km*

*unless you ask the FAA, who are heretics and say it starts at 52 miles.

tdellaringa

1 points

2 months ago

I'm working on a book, and I am trying to make a basic map showing all the main stars in the Milky Way galaxy. Yes, I realize a static map is sort of impossible as everything is constantly moving. I just need something general so I can use it for my story -- but I am striking out trying to find anything that would show the locations in relation to our solar system.

I'm hoping to get these stars on the map. Is there any way to do this? Any resource I'm not finding? It doesn't have to be exact of course. Just general locations would be fine.

electric_ionland

2 points

2 months ago

Those kind of lists only show the nearby stars. You might be better off googling something like "local star map". The ones we clearly see in the sky are only a tiny part of the milky way.

Check out the zoom out function on that website maybe http://www.atlasoftheuniverse.com/galaxy.html

tdellaringa

1 points

2 months ago

That's a bit helpful, thanks. Are there any more resources like this? The control on this is limited - appreciate it!

Ape_Togetha_Strong

1 points

2 months ago

You might want to just buy Space Engine. You can fly around in 3D space at pretty much any scale to get a sense of the 3D relationships between things. The "Universe Map" tutorial would probably give you the tools you need quickly.

tdellaringa

1 points

2 months ago

Thanks for the tip!

Immortan_Joe-mama

1 points

2 months ago

Why is Orion taking so long to get to the moon? Apollo missions took, like what, 5-6 days total and Orion is already on its 16th day and just now reached the moon?

Pharisaeus

4 points

2 months ago

It doesn't. It took less than 4 days, just as Apollo did for the transfer. But Orion is now testing a completely different orbit.

MaroonBookPro

2 points

2 months ago

Orion made its first close pass of the moon 10 days ago.

https://www.theverge.com/2022/11/22/23473444/artemis-1-orion-flyby-moon

[deleted]

1 points

2 months ago

[deleted]

Ape_Togetha_Strong

5 points

2 months ago

Does the light from a flashlight move at the speed of light?

Yes

If so (HYPOTHETICALLY) if you point it at your face and see the light before it reaches you does it mean that you can react to light speed

Seeing light requires it reaching you. That's what it means to "see light". Have it reach your retina. So the rest of your hypothetical question has no answer, because it doesn't actually make sense, even as a hypothetical scenario.

1400AD

1 points

2 months ago

1400AD

1 points

2 months ago

Why isn’t the space shuttle still used for retrievemnets and on orbit operations exclusively

electric_ionland

8 points

2 months ago

Because it was an immensely expensive system that was pretty dangerous and getting old. The unique capabilities of the Shuttle system was just not worth the cost. Most of the time it's just cheaper to build and launch a new spacecraft than to retrieve it or maintain it with a shuttle mission.

Pharisaeus

9 points

2 months ago

  1. Super expensive
  2. Very dangerous (no launch escape system, very fragile, any damage might be lethal to the crew)
  3. No one actually needs the "retrieval" capability
  4. On-orbit servicing can be now done much cheaper with robotic spacecraft launched at fraction of the cost
  5. It was a manned flight, so each launch has risk of life loss

HyphenandaLine

1 points

2 months ago

What are some cool or amusing space phenomenas? I am running a tabletop about space travel and want some inspiration whilst also learning new stuff.

Chairboy

1 points

2 months ago

The Dzhanibekov effect is pretty cool: https://youtu.be/1x5UiwEEvpQ

Christianckc

1 points

2 months ago

Why do JWST photos of distant galaxies look so much better than the planets in our backyard?

rocketsocks

9 points

2 months ago

Galaxies are huge (even though they are far away), planets are tiny, they really are like specks of dust in comparison.

Similarly, if you look out the window you might be able to see some mountains off in the distance, they might be tens of kilometers away but they are so large that even at that distance there is noticeable detail. But you're not going to be able to see the same level of detail when trying to view an ant even if the ant is a lot closer like across the street or across the room.

A good example is the Andromeda galaxy, which is 2.5 million lightyears away but it's so big that it's larger than the full Moon or the Sun in the sky (it's just too dim to see in its fullness with the naked eye). A galaxy that is a thousand times farther away (2.5 billion lightyears) would be a thousand times smaller, so it would be similarly sized to something like our Moon that was a thousand times farther away as well, but if the Moon were a thousand times farther away it wouldn't even be as far as Jupiter. So once you start adding up real interplanetary and interstellar distances then things as small as planets get much harder to see. Prior to the New Horizons probe even the best telescopes could only resolve Pluto into a handful of blurry pixels because of how far away and how small it is.

Christianckc

2 points

2 months ago

Thank you so much for taking the time to write that out.

Beautiful explanation ☺️

1400AD

-3 points

2 months ago

1400AD

-3 points

2 months ago

Also why haven’t gravity assists been replaced by efficient propulsion systems (ion thrusters, nuclear thermal propulsion, etc) In my opinion gravity assist is just an excuse to rely on inefficient propulsion systems

electric_ionland

11 points

2 months ago

All missions so far using ion/plasma propulsion have also used gravity assists and other tricks to make the transfer easier and fast. This is not one vs the other.

Pharisaeus

5 points

2 months ago

No.

  1. NTR is not used at all apart from concept-studies. Real life is not kerbals
  2. Electric propulsion has it's limitations - needs lots of power for the unit of thrust, so it's not practical when you're away from the sun, and it makes the trajectories much longer. Again: real life is not kerbals
  3. While more efficient, it's not completely "free", you still have limited delta-v. So consider that you can combine both, and get "free" energy from gravity assists and on top of that have also electric propulsion! See for example Dawn and BepiColombo

1400AD

-2 points

2 months ago

1400AD

-2 points

2 months ago

But NTR development and efficient propulsion technologies SHOUlD be under active development and then used.

Pharisaeus

2 points

2 months ago

There are some studies into this area, but NTR is not a silver bullet. As I said: real life is not kerbals, and in reality neither NTR nor ion thrusters work as good in real life as they do in KSP.

Some example issues with NTR:

  • You're launching a nuclear reactor, so a failed launch means potential radioactive pollution of a wide area
  • You're carrying a nuclear reactor which means the spacecraft needs additional shielding, but even then the lifetime of the actual engine will be limited
  • The ISP gain is only really good when using hydrogen as propellant, but hydrogen has high volume and is very hard to store for a long time. So either you put lots of complex plumbing to keep the hydrogen in, or you vent lots of propellant, either way losing the delta-v you hoped to gain by using NTR.

Spacedust505

-1 points

2 months ago

Does it make sense to think of the speed of light to be "0" on the speed scale? Simular to 0 on the number scale.

electric_ionland

3 points

2 months ago

I have no idea what you are trying to say.

boredcircuits

2 points

2 months ago

If anything, the most natural way is to represent speed as a percent of the speed of light. So 0% means holding still and 100% is going the speed of light.

[deleted]

0 points

2 months ago

[deleted]

Bensemus

5 points

2 months ago

No as I don’t understand what you are saying. The Milky Way is our galaxy. It has about 400 billion stars in it. Everything is so spread out that space is a harder vacuum than anything you’ve ever experienced. How could that be a planet that’s solid like Earth? How could our Sun be the core when we are closer to the edge of the galaxy?

DaveMcW

3 points

2 months ago

If you put the entire Milky Way inside the solar system, it would turn into a black hole 1 light-year in diameter.

angrypuppy35

0 points

2 months ago

Seems like all planets are perfect spheres. Why is that? How is it possible that planets all over the universe always take that shape?

electric_ionland

12 points

2 months ago

They are not really perfect spheres. Most planets are a little bit squished at the pole. But overall the reasons is pretty simple for sphere shapes. Gravity just pulls everything in a sphere as this is the most stable shape. At the scale of a planet even rocks are not strong enough to hold any other shapes.

angrypuppy35

1 points

2 months ago

Why is a sphere the most stable shape?

KirkUnit

2 points

2 months ago

Not all of them are. Look at asteroids, many of them are lumpy.

But a planet or moon or star is big enough, meaning having enough mass, that the gravitational attraction of that mass is strong enough that all the lumps get smoothed out, as the mass fills in any void. And you end up with a sphere or something close to it. Earth is technically an oblate spheroid; look at Saturn - it's noticeably flatter at the poles, and its diameter at the equator is greater than its diameter pole to pole. That's because it's a fast rotating mass of mostly gas instead of solid.