For Questions That Don't Merit Their Own Thread

[ProtoJeb21]

On September 14, 2016 at 9:39 AM, Spaceception said:

Most planets overall: http://www.openexoplanetcatalogue.com/planet/HD 10180 b/ 9 planets.

Largest Kepler system: http://www.openexoplanetcatalogue.com/planet/Kepler-90 h/ 7 planets.

Closest Multiplanetary system: https://en.wikipedia.org/wiki/Wolf_1061 3 planets

Although, if Proxima has more than 1 planet, than that would obviously be the closest Multiplanet system.

I find the Exoplanet Encyclopedia or NASA's Exoplanet Archive better, because they add ALL exoplanets. OEC hasn't even added the new K2 planets yet!

(also, there may be something orbiting Proxima between 60 and 500 days. Or maybe two objects. Who knows.)

[Spaceception]

3 minutes ago, ProtoJeb21 said:

I find the Exoplanet Encyclopedia or NASA's Exoplanet Archive better, because they add ALL exoplanets. OEC hasn't even added the new K2 planets yet!

(also, there may be something orbiting Proxima between 60 and 500 days. Or maybe two objects. Who knows.)

2??? Starshot gotta get funded so we can investigate.

@ProtoJeb21 I forgot that Ran also had potential planets So that's fixed.

[RainDreamer]

Seems like so far there have been no system with more than 9 planets. What  the theoretical limit on numbers of planets in a star system then?

[ChrisSpace]

On ‎9‎/‎13‎/‎2016 at 6:09 PM, p1t1o said:

You're welcome?

Its probably the best answer you are likely to get, its a recent study and its not like nuclear winters have a huge research topic behind them.

Not all nuclear winters are the same, how many weapons? What yield? Globally dispersed or more localised? Are they detonating in urban areas or over more remote targets? Which atmospheric model are you using to predict airflow? Which conflagration model are you using to predict smoke/soot particle size and distribution? Which weather model are you using to predict effects on agriculture?

And FYI, if you ever do find a model that can accurately give you an answer to your question given certain atmospheric properties, you will probably be a billionaire.

Its a hard question, its why you are asking it here.

 

I should actually come up with a sufficient answer to the second half of my question on my own, what I really need help with is the first bit:

On ‎9‎/‎12‎/‎2016 at 5:55 PM, ChrisSpace said:

On what day of the year (on average) would the Northern Hemisphere's food stockpiles be at their lowest amount?

 

[Spaceception]

11 hours ago, RainDreamer said:

Seems like so far there have been no system with more than 9 planets. What  the theoretical limit on numbers of planets in a star system then?

Dunno, I'm pretty sure it depends on the size of the parent star, the size of the planets, and how much material they worked with.

[RainDreamer]

1 hour ago, Spaceception said:

Dunno, I'm pretty sure it depends on the size of the parent star, the size of the planets, and how much material they worked with.

Hmm, so can it be said that giving an unlimited amount of material orbiting a star, there can be an unlimited amount of planets orbiting that star at the same time?

Then again, the total unlimited mass of the unlimited amount of planets would surely either rip the star apart or being dragged into the star to fuel it.

The question of finding the amount of planets possible on a star system is a tough one to even begin asking, now that I think about it. I can phrase it like, the maximum amount of earth-size planets on the least amount of orbits around a star of our size...but then that is just not realistic.

I guess I will ask something else like, what is the star system that we have theorized  to have the most planets in the universe? Like, not even confirmed through observation yet is ok.

[Spaceception]

15 minutes ago, RainDreamer said:

The question of finding the amount of planets possible on a star system is a tough one to even begin asking, now that I think about it. I can phrase it like, the maximum amount of earth-size planets on the least amount of orbits around a star of our size...but then that is just not realistic.

Your comment reminded me of this: https://planetplanet.net/2014/05/13/building-the-ultimate-solar-system/

Edited September 16, 2016 by Spaceception

[MOHR1951]

Am looking to buy good,used celestial mechanics textbooks,need books starting at a real basic level,progressing up to MS level.

 

[Wjolcz]

What kind of propellant/RCS fuel gives light blue plumes? I just watched a CGI of an ICBM being launched and the last stage's main engine and RCS plumes were blue. Was it exaggerated, or somthing?

EDIT: Nitrogen Tetroxide?

Edited September 19, 2016 by Veeltch

[DerekL1963]

9 hours ago, Veeltch said:

What kind of propellant/RCS fuel gives light blue plumes? I just watched a CGI of an ICBM being launched and the last stage's main engine and RCS plumes were blue. Was it exaggerated, or somthing?

EDIT: Nitrogen Tetroxide?

If you told us which ICBM it was, we could tell you...   If it was the Titan II it was Aerozine 50 and nitrogen tetroxide.

[Wjolcz]

3 hours ago, DerekL1963 said:

If you told us which ICBM it was, we could tell you...   If it was the Titan II it was Aerozine 50 and nitrogen tetroxide.

Minuteman, I think

[p1t1o]

15 hours ago, Veeltch said:

What kind of propellant/RCS fuel gives light blue plumes? I just watched a CGI of an ICBM being launched and the last stage's main engine and RCS plumes were blue. Was it exaggerated, or somthing?

EDIT: Nitrogen Tetroxide?

If it was CGI then all bets are off, they probably chose a "nice looking" colour.

Anyhoo, H2/LOX rockets can give a nice light blue plume, check out any picture of the shuttle taking off. It can be hard to see sometimes as blue flames are usually quite faint and can be washed out by daylight (or in the case of the shuttle, the glare from the solids). In space the plume will be practically invisible, unless it impinges on something.

As far as I know, minuteman is solid propellant in all stages and most solid rockets (such as shuttle solid boosters, also below) give a smoky bright yellow plume. Liquid-fuelled ICBMs are currently obsolete (long fueling times, cannot stand fueled for long, more unstable/dangerous).

[shynung]

@Veeltch A Titan II ICBM burns Aerozine 50 and NTO, which reacts into NO/NO2 (can be either), H2O, and CO/CO2. Majority of the exhaust are NOx and H2O, which are nearly invisible, as shown in this photo of Gemini 11 launch.

Note: The smoke from below isn't a part of the exhaust plume, it's water sprayed onto the pad to reduce noise.

[Kryten]

Minuteman has a liquid PBV using nitrogen tetroxide and MMH.

[p1t1o]

13 minutes ago, Kryten said:

Minuteman has a liquid PBV using nitrogen tetroxide and MMH.

Is that the "Bus"?

[Kryten]

Yes.

[Guest]

To the forum's biologists:

Is it possible to insert chloroplasts inside an animal cell (both alive) without killing it? Would the chloroplast produce enough ATP to keep the cell going?

[Wjolcz]

How do turbopumps work? As far as I understand they pump the rocket fuel and oxidizer, but do they use gasoline? They have an exhaust pipe, so I'd assume they do burn some sort of fuel and once it starts pumping the fuel, the rocket engine itself pressure feeds it, or something?

And btw, what's the exhaust byproduct of a methane and LOX engine?

Edited September 22, 2016 by Veeltch

[K^2]

With few exceptions, turbopumps use the same fuel as the main rocket, whatever it happens to be. With the difference that they run fuel-rich, so that the exhaust temperature stays low, and the exhaust is then also piped to the main chamber to finish combustion.

Methane-LOX will mostly produce carbon dioxide and water, some carbon monoxide, and the rest are impurities. In the atmosphere, however, some ammounts of nitrogen oxides and amonia could be produced in the plume due to atmospheric nitrogen reacting with various radicals.

[Kryten]

Some vehicles (generally old or legacy designs) do have separate fuel for the turbopumps; the V-2 used hydrogen peroxide and potassium permanganate catalyst to drive it's pump, and Soyuz still does.

[Aghanim]

How do I calculate the delta-V required for me to reach a certain orbit from ground, assuming that aerodynamic and gravity drag are negligible, and optimal ascent profile?

Lets say that I want to launch a rocket into 100km polar Kerbin orbit, so I tried to use the orbital velocity equation https://en.wikipedia.org/wiki/Orbital_speed

I entered 700km as orbit radius, and 5.2915793×10²² kg as Kerbin mass from http://wiki.kerbalspaceprogram.com/wiki/Kerbin into that equation, and I got 5045 m/s. Is it too much, or that is the correct amount of delta-V to orbit?

 

[K^2]

delta-V from ground to orbit depends on how you get there. Simplest and usually most fuel efficient transfer is to accelerate instantly from ground to Hohmann transfer then circularize at apoapsis. Wikipedia article on Hohmann Transfer has equations you need. Apoapsis radius will be target orbit, and periapsis will be radius of the planet. Your initial v is sidereal velocity of the planet, rather than orbital speed, however. You can look this up in your planet's entry in KSP wiki.

Although this assumes no drag and instant acceleration, for airless bodies, this should be close. For bodies with atmosphere, delta-V required will be substantially higher due to drag.

P.S. Don't use planet masses. KSP wiki has gravitational parameter, which replaces GM term in equations. Use that directly.

Edited September 22, 2016 by K^2

[DerekL1963]

4 hours ago, K^2 said:

With few exceptions, turbopumps use the same fuel as the main rocket, whatever it happens to be. With the difference that they run fuel-rich, so that the exhaust temperature stays low, and the exhaust is then also piped to the main chamber to finish combustion.

Nit:  Some rockets (most modern rockets) run the turbine exhaust to the main chamber.  Others just dump it overboard.  (Lower overall efficiency, but it simplifies the design and construction of the overall system as well as making it lighter.  There's always a trade off.)  Some early rockets sent it to nozzles and used it for attitude control.

[magnemoe]

On 22.9.2016 at 3:14 PM, Kryten said:

Some vehicles (generally old or legacy designs) do have separate fuel for the turbopumps; the V-2 used hydrogen peroxide and potassium permanganate catalyst to drive it's pump, and Soyuz still does.

Knew V2 used hydrogen peroxide as monoprop for the turbopumb but had no idea Soyuz still did.
Back during WW2 they had serious problems with jet turbines, the first German fighter jets had engines who just lasted a few hours but h2o2 gives steam so you basically have an steam turbine powering the pump. However in 1950 this was mostly solved, a lot of the German problems was lack of high temperature alloys. 

[Toonu]

I always wonder how fast is electricity? I've seen some blackout films with blackout cuting off the countries not so fast. I know too in pc, there's electricity...bla...bla. So how fast is it? Faster than sound? More? Less? By electricity I mean electricity in computers or wiring above ground(that big weird looking slopes). Looking forward for answer!

Ave! Toonu