For Questions That Don't Merit Their Own Thread

[PB666]

Is it possible to have a neutron star system with the satellites all in stable orbits? If so what would such a planet look like, how would it differ from your everyday good old yellow generic MS star system, and how would the satellites be affected? What would be the constraints for planets if there are to be any unique ones? What would the star look like to an observer that stands on the surface of a satellite? Pushing it further, is it possible to have a habitable planet around a neutron star?

All a neutron star is a star who mass has collapsed. They are in a category of stars that would have exploded as a supernova, so that any close planets would likely be taken. I suppose that any remaining planets would have to have a fairly dense mass, relatively far away, and one can assume an eccentric orbit. Adjacent binary stars can also become neutron stars and they are satellites in a sense. Planets further away may survive, they might assume more eccentric orbits, the loss of mass from their star and the explosion causing many distal planets to be ejected into space.

[Kryten]

I suppose that any remaining planets would have to have a fairly dense mass, relatively far away, and one can assume an eccentric orbit.

That's exactly what we would expect, but the only neutron star planets we know of (these ones) are small, close, and have low eccentricity.

[theend3r]

All a neutron star is a star who mass has collapsed. They are in a category of stars that would have exploded as a supernova, so that any close planets would likely be taken. I suppose that any remaining planets would have to have a fairly dense mass, relatively far away, and one can assume an eccentric orbit. Adjacent binary stars can also become neutron stars and they are satellites in a sense. Planets further away may survive, they might assume more eccentric orbits, the loss of mass from their star and the explosion causing many distal planets to be ejected into space.

Why dense mass? Sure, they need to be far away to not be torn apart by tidal forces but otherwise the only thing needed to keep an orbit is velocity.

[andrewas]

We have detected planets around neutron stars, which was unexpected because the supernova should have blown them all away. Some are thought to have formed from debris left from the original star system, others may be captured from other stars, I think one is thought to be a star which had its outer layers removed by the supernova of its partner, leaving a planetary mass remnant.

[theend3r]

Q: Would it be possible to create a propulsion using magnets and Earth's natural magnetic field? E.g. using Halbach array with extremely strong magnets. (Or of course using magnetic monopoles if it were possible to make them.)

[PB666]

We have detected planets around neutron stars, which was unexpected because the supernova should have blown them all away. Some are thought to have formed from debris left from the original star system, others may be captured from other stars, I think one is thought to be a star which had its outer layers removed by the supernova of its partner, leaving a planetary mass remnant.

As far as I know most stars undergo to much turbulation to have a solid core and old dying star, or one with a very high iron content, but then it would be on its way to nova anyway.

[Trann]

I've been looking for a thread like this! Something has been troubling me...

How do you pronounce (no, no, I kid). Happy Friday, all.

[More Boosters]

All a neutron star is a star who mass has collapsed. They are in a category of stars that would have exploded as a supernova, so that any close planets would likely be taken. I suppose that any remaining planets would have to have a fairly dense mass, relatively far away, and one can assume an eccentric orbit. Adjacent binary stars can also become neutron stars and they are satellites in a sense. Planets further away may survive, they might assume more eccentric orbits, the loss of mass from their star and the explosion causing many distal planets to be ejected into space.

Yes, I meant to ask if planets could survive such events; supernovas. I also wondered about orbital velocities closer to the star as the remnant is much denser, meaning you could get closer, correct?

[PB666]

Yes, I meant to ask if planets could survive such events; supernovas. I also wondered about orbital velocities closer to the star as the remnant is much denser, meaning you could get closer, correct?

1. 2-body problem works better if the central gravitational object approaches a point source.

2. Objects that orbit very close to massive objects undergo some time dilation, this alters n-body problems.

3. Objects that orbit very very close can be torn apart by differential gravity. In a sphere in orbit the arc-disk that is in the orbital plane has GM/r^2 = w^2 r. Those that are below the centripedal force is below gravity and those abovel th centripedal force is above gravity.

4. Survival depends on composition. A planet composed largely of volatlie matter ( given that everythig is volatile at some point) but some molecules will vaporize lower the density of the atmospere by thermal expansion which can be blown away. I suspect when they say blown away they mean a combination of thermal degassing reducing the planet to a rocky fraction of itself, alterations of it orbit due to the loss of mass in the central mass, and destabilzation of the orbit by a gravitational wave as well as kinetic effects of the blast. The fact the see neutron stars in orbit of each other suggest something can survive.

I forgot to add that as neutron stars collapse thier surface angular momentum can be partially brought tobthe new surafce, this can cause them to spin rapidly creating a pulsar, this can have a very disruptive effect on nearby matter, as it is essentially a high potential thermal osscilator.

Edited August 22, 2015 by PB666

[worir4]

What is the bit of ocean called in between the KSC and the Island runway?

[WinkAllKerb'']

"this time you failed to take off", it could at least ; )

(may be a little wood panel at the very end of the runaway close to the shore could be added just for fun ; )

http://thumbs.dreamstime.com/z/panneau-routier-en-bois-tr%C3%A8s-vieux-de-fl%C3%A8ches-34472098.jpg

Edited August 22, 2015 by WinkAllKerb''

[PB666]

http://newsroom.ucla.edu/releases/new-spectroscopy-technique-provides-unprecedented-insights-about-the-reactions-powering-fuel-cells

The bigger problem is converting electricity into power.

- - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - -

http://www.makeuseof.com/tag/new-technology-halves-cost-lithium-ion-batteries/

This sounds like an exaggeration, what they need is a new lithium Ion battery that is almost efficient but uses less lithium and uses more cheaper materials.

Otherwise what we need is a cheaper way to extract lithium from Sea Water.

Edited August 22, 2015 by PB666

[Motokid600]

1.) Does the output log reset itself after restarting the game? Or does it continuously record?

2.) Do struts still nullify decoupler force?

[More Boosters]

How come a planet like Tylo doesn't have an atmosphere? It is very large and the smaller Laythe nearby has not only an oxygen atmosphere but entire seas and all that, and in my limited knowledge it would have attracted the gasses to form an atmosphere unless it was stripped away from the sun but it's also very far away from the sun, and also in my limited knowledge larger planets would cool down slower, thus losing their magnetic field later, so what gives?

[peadar1987]

How come a planet like Tylo doesn't have an atmosphere? It is very large and the smaller Laythe nearby has not only an oxygen atmosphere but entire seas and all that, and in my limited knowledge it would have attracted the gasses to form an atmosphere unless it was stripped away from the sun but it's also very far away from the sun, and also in my limited knowledge larger planets would cool down slower, thus losing their magnetic field later, so what gives?

Perhaps Laythe is inside Jool's magnetic field, and thus protected from solar wind, whereas Tylo is further out and had its original atmosphere stripped away.

[RocketPilot573]

1.) Does the output log reset itself after restarting the game? Or does it continuously record?

It resets and makes a new log for every game restart.

2.) Do struts still nullify decoupler force?

No, pretty sure that was fixed.

[Motokid600]

thanks so much. Wish I knew that earlier. So many times spent restarting the game to delete the log file in order to post a "clean" one for a bug report.

[RainDreamer]

What is the ISP of a vigorously shaken 1.5l bottle of carbonated drink? How much delta V does it have when strapped on to an average astronaut?

[K^2]

What is the ISP of a vigorously shaken 1.5l bottle of carbonated drink? How much delta V does it have when strapped on to an average astronaut?

It's hard to give a solid estimate, because there are a lot of factors. But it's easy to put an upper limit on it. Soda bottle is pressurized to about 2 bar, or 200kPa. If we assume that CO2 is released at sufficient rate to maintain that pressure, the total energy liberated in 1.5L would be about 300J. For 1.5kg of propellant, we get 10m/s exhaust velocity. That's I_SP of 1.02s. Realistically, you'll probably get close to that early on, but it will quickly drop to a much lower value. So average I_SP is likely to be lower.

It might also be more useful to consider total impulse in this case. Again, considering an upper limit, the total impulse works out to 10m/s * 1.5kg = 15Ns. If we consider a typical astronaut in a space suit, which is about 130kg, we get delta-V 15Ns / 130kg = 0.12m/s. Which really isn't much to begin with, and will likely be even less in practice.

You could use rocket formula here, but since initial and final masses are almost identical, you should get the same result.

[KerikBalm]

There was a project of a militarized Soyuz known as Soyuz VI. It carried Pu-powered RTGs instead of solar panels, which saved weight, increased operational capability and reliability, and provided more power for the military equipment.

As you can see on this diagram, the RTGs were on the outside, on extended arms, and angled to minimize radiation on the crew module.

http://www.astronautix.com/graphics/s/soyvi.jpg

The Soviets obviously thought that the risk of irradiating the crew justified the additional complexity that design, so I don't really think it is that benign.

https://en.wikipedia.org/wiki/Strontium-90#Radioisotope_Thermoelectric_Generators_.28RTGs.29

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#90Sr

Are you sure they were Pu-238? The Soviets also used Strontium 90 extensively.

Also, maybe there were thermal concerns for sticking them farther out?

[More Boosters]

How come a planet like Tylo doesn't have an atmosphere? It is very large and the smaller Laythe nearby has not only an oxygen atmosphere but entire seas and all that, and in my limited knowledge it would have attracted the gasses to form an atmosphere unless it was stripped away from the sun but it's also very far away from the sun, and also in my limited knowledge larger planets would cool down slower, thus losing their magnetic field later, so what gives?

Bump as it seems to have been lost in the page transition.

[peadar1987]

Bump as it seems to have been lost in the page transition.

Replying again as it seems to have been lost in the page transition:

Perhaps Laythe is inside Jool's magnetic field, and thus protected from solar wind, whereas Tylo is further out and had its original atmosphere stripped away.

[KerikBalm]

Bump as it seems to have been lost in the page transition.

Because its a game and the designers wanted to give us an interesting challenge?

Because it has a small radius and escape velocity, and pretty much every planet in the game except Jool wouldn't be able to hold on to much of an atmosphere.

Even jool wouldn't be able to hold on to an atmosphere as well as earth, assuming equal sollar irradiance (which Jool should have less of, assuming kerbol to be a red dwarf, and that the irradiance at Kerbin is equal to what Earth receives)

[More Boosters]

Because its a game and the designers wanted to give us an interesting challenge?

Because it has a small radius and escape velocity, and pretty much every planet in the game except Jool wouldn't be able to hold on to much of an atmosphere.

Even jool wouldn't be able to hold on to an atmosphere as well as earth, assuming equal sollar irradiance (which Jool should have less of, assuming kerbol to be a red dwarf, and that the irradiance at Kerbin is equal to what Earth receives)

Uhh, Tylo is pretty large, even larger than Kerbin, so I take it that you're not scaling it up to the real world scale. I mean, Kerbol apparently couldn't even be a sun in real life, so taking the KSP values as they are is a bit odd. I meant to ask for a planet like Tylo, I believe the entire system is scaled by a factor of 1/10 so that should be considered.

[Kinglet]

How much dpi would you need to be able to zoom in on a picture of yourself taken at arms length, and see the quarks making up the parts of your atoms?