The thread for space cadets!

Happy 30th Birthday Hubble telescope. At it has given us the birthday present:
_111924069_body.jpg

This one is of a star-forming region close to our Milky Way Galaxy, about 163,000 light-years from Earth. The larger object is the nebula NGC 2014; its companion is called NGC 2020. But astronomers have nicknamed the scene the "Cosmic Reef" because it resembles an undersea world.
 
Happy 30th Birthday Hubble telescope. At it has given us the birthday present:
_111924069_body.jpg

This one is of a star-forming region close to our Milky Way Galaxy, about 163,000 light-years from Earth. The larger object is the nebula NGC 2014; its companion is called NGC 2020. But astronomers have nicknamed the scene the "Cosmic Reef" because it resembles an undersea world.

speaking of space cadets where is @hobbsyoyo been?
 
ı would calculate that to be an idea that he could be carried away amongst his friends in CFC . Nobody in his right mind would ever consider me friendly , but even that can come into effect . Check my last post in the thread , heading the last page , ı think . Where it can be made to look like or directly interpreted to say American rights in space to be challenged , because ı have no obligation to avoid destroying American satellites and what not except , you know , me being a decent well behaved person . What does not mean for the US Space lndustry ? That it will have no reason to exist ? What does that mean for someone who has obviously spent his life to be part of the said ?

unjustified and silly r16 posts . Convictions to be never judged , before commitments fully considered . My country has been through a farce , making my experience a farce of a farce , but you can't tell until you have some measure of people who will or might try to impose things on you . Somewhat or actually competent or heroes like "köpeksiz köyde değneksiz gezenler" , people boldly walking around in the village , not carrying a stick as there are no dogs . For which you might need some history stuff on whether it was possible to be eaten by street dogs in lstanbul of the 19th century . No , ı was the same way before the attack on Tankograd , which you won't look up for , because you know where the browser will take you and whom . So , it was Obama's fault anyhow ... ? ...

said r16 posts are silly and full of rants . People should have linked the thread where people talk of whom who leave and arrive and there is like this unjustified thing there about Darth Vader waking up to find himself imprisoned into a "prison" by Palpatine and losses and stuff . Well , the Stuntwoman could have been arranged to call that person , because she was in one of that person's newer films as a passerby in the street and might have the phone number and that person would have said "Uh, that was 2005 and it's a movie and I have made a few more since then... And have an Oscar, too!" so like no point for stuff . Am not Lord Vader in any case .
 
Uranus the going theory is an impact knocking it over. For Venus the last I've heard it was tidal locking with some backspin put on it by the atmosphere. Still an active area of research mind you
 
We may have lost our resident rocket scientist but does anyone know why space ships dont burn up while leaving the atmosphere? Why cant a ship enter the atmosphere at about the same speed it leaves or is that an impossibility with our current technology?
 
I'm not an expert or rocket scientist, but I have played Kerbal Space Program and was trained by a rocket scientist

does anyone know why space ships dont burn up while leaving the atmosphere?

They don't burn up because they're not travelling fast enough wrt the atmosphere to burn up.

Why cant a ship enter the atmosphere at about the same speed it leaves or is that an impossibility with our current technology?

When you're entering an atmosphere from orbit you're always moving at very fast speeds. There is no way around that. You're either going to be in orbit or you're going to be doing a planet flyby. If you're doing a flyby, you're going even faster, and not even a heat shield might be good enough depending on your entry vector

Being in orbit is the best you can do. Ideally you'll set up an orbit right above the atmosphere.. that's the best you can do.. but you're still moving really fast, wrt to the ground you're moving faster than escape velocity I believe. In order to slow down you will have to enter the atmosphere, you can't slow down and stay in orbit.

Or something like that
 
thats what I dont get, seems like we could have a ship expend fuel to slow down to roughly match the rotation of the Earth so the friction of entering doesn't burn the ship up. Maybe our fuel etc is just too 'primitive' at this point but it cant be long before we figure that out.
 
The problem is that you can't make ship going slower and stay on the same orbit. As soon as you start slowing it down, it will enter the atmosphere still at high speed. To prevent this, you will need to burn a lot of fuel to maintain altitude and also burn it during descent to keep the speed low. As far as I understand the amount of fuel for that would be impractically large.
 
I'm not an expert or rocket scientist, but I have played Kerbal Space Program and was trained by a rocket scientist



They don't burn up because they're not travelling fast enough wrt the atmosphere to burn up.



When you're entering an atmosphere from orbit you're always moving at very fast speeds. There is no way around that. You're either going to be in orbit or you're going to be doing a planet flyby. If you're doing a flyby, you're going even faster, and not even a heat shield might be good enough depending on your entry vector

Being in orbit is the best you can do. Ideally you'll set up an orbit right above the atmosphere.. that's the best you can do.. but you're still moving really fast, wrt to the ground you're moving faster than escape velocity I believe. In order to slow down you will have to enter the atmosphere, you can't slow down and stay in orbit.

Or something like that
Ah, KSP, the only game i have learnt things of.
 
We may have lost our resident rocket scientist but does anyone know why space ships dont burn up while leaving the atmosphere? Why cant a ship enter the atmosphere at about the same speed it leaves or is that an impossibility with our current technology?

Theoretically, a space ship could do that, but it would require a huge amount of fuel. You would need a rocket about the size of those used to launch the space ship and then you would need a much bigger rocket to put that rocket into orbit.

thats what I dont get, seems like we could have a ship expend fuel to slow down to roughly match the rotation of the Earth so the friction of entering doesn't burn the ship up. Maybe our fuel etc is just too 'primitive' at this point but it cant be long before we figure that out.

The point is that you want the friction to save fuel. Putting a heat shield on the space ship and use the friction to slow down is much more efficient than trying to use fuel to accomplish the same.
 
How would you even slow down in orbit but stay at the same altitude? If you burn retrograde your orbit gets smaller. In which direction would your burn be to make this happen? I am trying to visualize this and failing
 
How would you even slow down in orbit but stay at the same altitude? If you burn retrograde your orbit gets smaller. In which direction would your burn be to make this happen? I am trying to visualize this and failing
Retrograde and "downwards" (to direct the ship away from the planet and compensate acceleration from gravity).
 
What's the best way to explain how that works? If you burn retrograde your periapsis will lower. If you burn away from the planet your apoapsis will increase in height. Do both of these actions balance out as you make your way around the planet? It's not easy to wrap your mind around. It seems like what would happen is you would slowly move away from the planet at first, but then enter the atmosphere as your periapsis gets so low that it intersects with the atmosphere and then planet.

Is this how geostationary statellites are put into orbit? Except the amount of fuel required to do this is much lower since the satellite is small?
 
What's the best way to explain how that works? If you burn retrograde your periapsis will lower. If you burn away from the planet your apoapsis will increase in height. Do both of these actions balance out as you make your way around the planet? It's not easy to wrap your mind around. It seems like what would happen is you would slowly move away from the planet at first, but then enter the atmosphere as your periapsis gets so low that it intersects with the atmosphere and then planet.

Is this how geostationary statellites are put into orbit? Except the amount of fuel required to do this is much lower since the satellite is small?



You use a computer to calculate the thrust which balances the "up" thrust against the "down" force while using other thrusters to slow your orbital speed. But as others have said, doing that would require a really large quantity of fuel. Objects in low Earth orbit are traveling very fast.

A geostationary satellite is in a far higher orbit. Like 22000 miles or so higher than low orbit, which is little more than 100 miles. Even a small satellite takes a lot of thrust to get to geostationary orbits. But once there, the speed of the orbit balances the pull of gravity so they're stable(ish).
 
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