Thread: Ask me about Space

What's your favourite thing about it?

I think it's so cool the sky is such a beautiful blue when we look up ...but there's a specific reason why right? ( I know I could google this but never bothered )

Oh! I have a question! What do think would happen if an astronaut or a spacecraft, goes inside a black hole?

Originally Posted by JadeGreen

Anything to do with outer space. (Planets, Stars, Galaxies, Spacecraft, History, etc.) I'm a bit of a space nerd, but there's no way I know everything. If I don't know the answer to your question, I'll try looking it up, and we'll both learn from it.

Not sure if this is true or I'm just a complete dumbass, are humans made of stardust? Not sure if it's space related.

What's the most interesting type of star in your opinion? And why?

What do you think would happen if it was possible for scientists to send nuclear waste to the sun?

Originally Posted by DreamCafe11

What do you think would happen if it was possible for scientists to send nuclear waste to the sun?

It would just burn up and spread through the sun, so scientists wouldn't do it as there's no scientific benefit from it. If it was possible to send nuclear waste to the sun, it would still be cheaper to bury it in an asteroid thick enough to shield the waste from outside interference, or leave it at a Lagrange point, or in Jupiter. Even ejecting the waste from the solar system probably takes less fuel than throwing it into the Sun. (Source: many hours of Kerbal Space Program )

EDIT: Chart of fuel costs from Earth to various points in the Solar System. Based on these numbers and without using 'gravitational slingshot' maneuvers around Venus and Jupiter to save fuel, sending something from Earth's surface to the Sun takes over 208 km/s delta-V, but ejecting an object from the Solar System takes only 18.15 km/s. That's ~11.5 times more delta-V to send waste into the Sun than to eject it from the solar system, which means a lot more than 11.5 times more fuel (you need more fuel to carry more fuel, so you get diminishing returns). Ejecting something from the Solar System into the great black beyond is a pretty sure way of making sure nobody will look for it or find it.

You'd have to be dealing with something a lot more dangerous than radioactive waste to want to destroy it so thoroughly that throwing it into a star is your only option.

Originally Posted by Patience108

What's your favourite thing about it?

I think it's so cool the sky is such a beautiful blue when we look up ...but there's a specific reason why right? ( I know I could google this but never bothered )

Bah! First question you already stumped me. Wonderment of scale and awe, is probably the best way of putting it. I remember when I was 10, and I went the observatory in Hawaii, and looked at Jupiter live through a very powerful telescope. If you've ever observed Jupiter through a good enough telescope, come back a couple hours later and look at it again, the moons will have moved in their orbits. (I think Io's orbital period is only about a day.) Something about seeing that, and knowing that I was really looking at these other worlds moving around a giant swirling ball of gas. That's what got me into space. Why it fascinates me so much is difficult to say exactly...

Oh! I have a question! What do think would happen if an astronaut or a spacecraft, goes inside a black hole?

I know as you get near a black hole, Gravity would 'Spagettify' you. (Yes, that's the real term for it) where you would be stretched. Because Gravity loses strength divided by distance squared, so as you get close, the gravity gradient increases really quickly. I'm pretty sure gravity dilates time as well... But you're asking what happens when you cross the event horizon. Even the best physicists don't know, since black holes are a point of infinite gravitational attraction, a bottomless hole in the fabric of space time. Some say you might find yourself in a parallel universe, or a distant corner of our own universe.

I honestly have no best guess as to what would happen to you if you went inside of a black hole. (Best physicists on the earth can't agree.) But if you want to try it, I do know this. Supposedly a larger black hole would be easier to enter, because the gravity gradient is less extreme and therefore there will be less of a difference between the gravity on one side of your ship/astronaut and the other, and thus you wouldn't be spagettified. (I just love that word... )

Not sure if this is true or I'm just a complete dumbass, are humans made of stardust? Not sure if it's space related.

tl;dr: Yes

Long Version:

When the universe formed it was mostly Hydrogen and Helium. (The lightest elements on the periodic table, with one and two protons, respectively.) And when stars 'burn' they are actually fusing Hydrogen together. I won't get into the nitty gritty of fusion reactions, but this releases energy as well as creates new heavy elements. The heavier the elements you are fusing the more energy you have to put into fusing them, and the smaller return of energy return you get back out.

Every Star works on the same principle. Gravity pulls the star inward, and energy produced by fusion pushes the star outward. If it wasn't for Fusion, the star would just be like a big cold gas planet, or a black hole if it was massive enough. (Like a large planet), and if it wasn't for gravity, stars would just float off into a cloud of gas and never have the temperature and pressure to achieve fusion.

Essentially what a Star is is a giant perpetually exploding nuclear fusion bomb that's held together by its own gravity.

Large stars produce the heaviest elements, because when they run out of Hydrogen to fuse, they start to collapse because they aren't producing anymore heat. This means that the force of gravity increases and this can impart enough energy to fuse Helium into Carbon. The way this happens is... hard to explain, but what will end up happening is that layers will being to form inside the star of increasingly dense elements. Each time a new layer forms, the star will expand, but as it loses more energy expanding that layer, then a new layer forms and it expands out. This can cause stars to expand and contract (over very long periods of time) as they work their way up the periodic table.

This happens until the star begins to produce Iron, (26 protons.) Iron crosses the threshold and takes more energy to fuse than it produces from the fusion reaction. Stars rely on the energy that comes from fusing elements, it is what keeps them from collapsing in on themselves.

So when the large star suffers critical energy loss, gravity takes over and it pulls in on itself. This is essentially the pulse happening one last time. This causes absurd temperatures and pressures and the material will blast back out creating a Supernova. The core of the star will become a Neutron star or a Black hole depending upon how big the star is, and the sheer force of the blast imparts energy and fuses all of the elements with more protons than Iron on the periodic table. (Doesn't matter any more if they take more energy to fuse than they put out in the craziness of the supernova.) This is why some elements like Gold (79 Protons) are so rare.

There's a whole lot more to this, but that's the cliff-notes version. Yes, all of the heavy elements, Carbon, Oxygen, Iron, Calcium and everything else in our body is leftovers from a supernova.

What's the most interesting type of star in your opinion? And why?

Somebody's gonna shout at me for being really lame for saying this, but I've always liked Red Dwarfs. They are the most common type of stars, but they live the longest (Some over a A Trillion Years or more). Keep in mind the universe is only 13.7 Billion years old. This means that a Red Dwarf born right after the big bang would have only lived about 1.4% of its total lifespan by now. If I got to pick, I'd put my home planet around a Red Dwarf, because I'd know it wasn't going anywhere anytime soon.

Binary star systems are cool too. Maybe two red dwarfs orbiting very close around a common center of mass. They could keep each other company...

What do you think would happen if it was possible for scientists to send nuclear waste to the sun?

Nothing particularly interesting would happen to the sun. Even if you dropped all the worlds' nuclear waste into the sun, it wouldn't do much, simply because of the scale of it.

I talked about in the previous question how heavy elements like iron cause problems with stars. But this needs to be on a massive (like bigger than earth) scale before it will have any effect on the star. So even though asteroids filled with Iron and other heavy elements probably fall into the sun all the time, it doesn't explode. Because even though there might be some heavy elements muddying up the core of your star, there's still vastly more hydrogen than anything else that the sun can fuse. Since the heavy elements aren't getting enough gravitational energy, they won't be able to fuse. (They might split if they're hit with an alpha or beta particle in the right way.)

SAO, You little ninja. I'm here typing away at this long post.

Originally Posted by SwordArtOnline

It would just burn up and spread through the sun, so scientists wouldn't do it as there's no scientific benefit from it. If it was possible to send nuclear waste to the sun, it would still be cheaper to bury it in an asteroid thick enough to shield the waste from outside interference, or leave it at a Lagrange point, or in Jupiter. Even ejecting the waste from the solar system probably takes less fuel than throwing it into the Sun. (Source: many hours of Kerbal Space Program )

EDIT: Chart of fuel costs from Earth to various points in the Solar System. Based on these numbers and without using 'gravitational slingshot' maneuvers around Venus and Jupiter to save fuel, sending something from Earth's surface to the Sun takes over 208 km/s delta-V, but ejecting an object from the Solar System takes only 18.15 km/s. That's ~11.5 times more delta-V to send waste into the Sun than to eject it from the solar system, which means a lot more than 11.5 times more fuel (you need more fuel to carry more fuel, so you get diminishing returns). Ejecting something from the Solar System into the great black beyond is a pretty sure way of making sure nobody will look for it or find it.

You'd have to be dealing with something a lot more dangerous than radioactive waste to want to destroy it so thoroughly that throwing it into a star is your only option.

She asked what would happen IF you dropped nuclear waste waste into the sun, not what a pain in the butt (and wallet) it would be TO drop the world's nuclear waste into the sun. But you are 110% Correct, SAO it would be a huge pain financially to do so and a massive engineering challenge. Particularly since nuclear waste is HEAVY elements. (And there's a lot of it.)

But of course, your many hours of Kerbal Space Program would also tell you that you don't sun-dive From earth orbit, you transfer out to a higher orbit around the sun, then burn retrograde there, or use a planetary gravity assist. It takes longer but you use less DV. I don't think it matters what orbit or gravity assist you use though, just getting the entire world's nuclear waste into LEO is gonna be much more effort than its worth just to bury it underneath the salt flats or something.

Originally Posted by SwordArtOnline

It would just burn up and spread through the sun, so scientists wouldn't do it as there's no scientific benefit from it. If it was possible to send nuclear waste to the sun, it would still be cheaper to bury it in an asteroid thick enough to shield the waste from outside interference, or leave it at a Lagrange point, or in Jupiter. Even ejecting the waste from the solar system probably takes less fuel than throwing it into the Sun. (Source: many hours of Kerbal Space Program )

EDIT: Chart of fuel costs from Earth to various points in the Solar System. Based on these numbers and without using 'gravitational slingshot' maneuvers around Venus and Jupiter to save fuel, sending something from Earth's surface to the Sun takes over 208 km/s delta-V, but ejecting an object from the Solar System takes only 18.15 km/s. That's ~11.5 times more delta-V to send waste into the Sun than to eject it from the solar system, which means a lot more than 11.5 times more fuel (you need more fuel to carry more fuel, so you get diminishing returns). Ejecting something from the Solar System into the great black beyond is a pretty sure way of making sure nobody will look for it or find it.

You'd have to be dealing with something a lot more dangerous than radioactive waste to want to destroy it so thoroughly that throwing it into a star is your only option.

Originally Posted by JadeGreen

SAO, You little ninja. I'm here typing away at this long post.



She asked what would happen IF you dropped nuclear waste waste into the sun, not what a pain in the butt (and wallet) it would be TO drop the world's nuclear waste into the sun. But you are 110% Correct, SAO it would be a huge pain financially to do so and a massive engineering challenge. Particularly since nuclear waste is HEAVY elements. (And there's a lot of it.)

But of course, your many hours of Kerbal Space Program would also tell you that you don't sun-dive From earth orbit, you transfer out to a higher orbit around the sun, then burn retrograde there, or use a planetary gravity assist. It takes longer but you use less DV. I don't think it matters what orbit or gravity assist you use though, just getting the entire world's nuclear waste into LEO is gonna be much more effort than its worth just to bury it underneath the salt flats or something.

Wow.You guys sure do know a lot. I didn't know playing that game could teach you that much.I still haven't tried it from the time I found out about it. >.>" But thanks for answering my question. ^^

Do you know about Secret Space Program?

I actually got really curious about this concept and made it up in KSP. 731 Tons of Rocket to Dispose of ~3 tons of nuclear 'Waste' as quickly and efficiently as we could.. I used the near future parts pack that and put a reactor fuel storage container on top and filled it with Enriched Uranium, because the only thing more wasteful than throwing away spent nuclear fuel on giant rockets is shooting perfectly good unused nuclear fuel on rockets.

This website says that the nuclear industry has produced 74,258 tons of high-level waste in the last four decades. So you would need about 25,000 of these rockets to do the job. And this is KSP where rockets are "easy".

I'm curious how much would this cost. Let's assume this rocket costs as much as a Saturn V (Since it kind of looks like one...) (That's 41,400,000,000$ in todays money according to Wikipedia) So that comes out to a humbling 1,035,000,000,000,000$ or about a Quadrillion Dollars.

Granted these are my back-of-the-envelope calculations using a silly game about little green men, and the first page of google search results. Sorry for going on and on about this, But thought experiments like this are always fun.

Do you know about Secret Space Program?

I do now...

What is your current thought about Secret Space Program? You don't have to believe it haha, I know it's crazy. But super interesting how it's very detailed and a lot of those advanced technology do make sense, like anti-gravity and electromagnetic propulsion that can make heavy object fly totally fast. It doesn't make sense at all that we're the only intelligent beings in the universe either. Too bad NASA is hiding these (if it's true). I feel like we're only eavesdroppers on what's really going on.

What is your current thought about Secret Space Program? You don't have to believe it haha, I know it's crazy. But super interesting how it's very detailed and a lot of those advanced technology do make sense, like anti-gravity and electromagnetic propulsion that can make heavy object fly totally fast. It doesn't make sense at all that we're the only intelligent beings in the universe either. Too bad NASA is hiding these (if it's true). I feel like we're only eavesdroppers on what's really going on.

Well, they seem to take a little to the tinfoil hat side of the force. (Right up the alley of the people on that Ancient Aliens show my dad likes.) People are always making up conspiracies and stories about aliens and advanced technology. I'll have an open mind to anything, I don't think any less of someone if they believe in this stiff, but I, personally doubt that the government is really hiding aliens or anything. If they are, then I was wrong and that's that. It's not 100% impossible that the government is hiding alien technology or something, but I think it's highly unlikely given what I know about how our world works.

Ah, it was late at night (like it is now) and I completelymessed up. The numbers are just wrong - as long as you don't mind hitting the Sun at 616 km/s, even a simple Hohmann transfer to the Sun takes 38km/s from Earth surface, not 208km/s delta-V (which would circularize your orbit over the Sun).

Originally Posted by JadeGreen

you transfer out to a higher orbit around the sun, then burn retrograde there, or use a planetary gravity assist. It takes longer but you use less DV.

I totally forgot about the bi-elliptic transfer - if you do a bi-elliptic transfer up to Neptune's orbit and back down it comes in under 22.7 km/s, but it takes about 62 years to reach aphelion and a few more decades to come back to the Sun. The figure for ejecting from the Solar System is 18.15 km/s. You can get the dV cost for sundiving down close to 18.15 km/s by going out even further, provided that your spacecraft survives long enough to make a burn at the aphelion.

So, assuming our spacecraft can survive for 62 years, it's only 25% more expensive to sundive than to eject from the Solar System, not orders of magnitude as I originally said. That's still completely ignoring gravity assists.

That's what I get for trying to be smart on the Internet.

What actually is space? The more I read about this the more convinced I an that space is NOTHING. The same goes for time. What is time? Nothing.

Forget my other question.

Originally Posted by sanctispiritus

What actually is space? The more I read about this the more convinced I an that space is NOTHING. The same goes for time. What is time? Nothing.

Well one could say that space is the three dimensional plane that we inhabit and time is the progression of events from one to the next, but you've probably already heard those definitions if you've been reading about the subject. Let's hear your point of view, why are space and time nothing?

Einstein said space is curved. I always wondered, if one travels in a straight line on the surface of the Earth (or any sphere), one would end up back at the same point due to its curvature, however, due to the size of the Earth, this curvature may not be apparent to the traveler. By conjecture, if one travels by space ship in any direction into space and only goes in a straight line, will they end up back at the same point due to the curvature of space?