For Questions That Don't Merit Their Own Thread

[kerbiloid]

It's always fine to hear again the non-proliferation stories in the world, full of rocket and nuclear countries, and many thousands of specialists, able to help the rocket/nuke wannabes, and getting not even a cent from the sponsored budgets, to be affected by the NASA payments...

I would remind, that India, Pakistan, DPRK, Israel were in game long before the payments began.

And the post-USSR republics were fool of specialists and hardware, which could be easily rented by the interested countries, and weren't paid from NASA.

NASA was paying because it had reasons to pay.

Edited November 10, 2023 by kerbiloid

[DDE]

2 hours ago, kerbiloid said:

NASA was paying because it had reasons to pay.

I think that's half the story. They wouldn't have gotten the extra money otherwise if they hadn't invented such a beautiful excuse.

[kerbiloid]

NASA: "But..."
X: "Shut up, and give'em this money."

[DerekL1963]

On 10/24/2023 at 11:26 PM, SunlitZelkova said:

Why didn’t anyone care about spaceflight in the 2000s?

Same reason they didn't care in the 70's, 80's, or 90's - people don't care about space.  Has nothing to do with any other hand waving or smoke blowing BS.  People don't care about space.  Despite decades of mythmaking, they only barely cared in the 60's...  and that was only about a Cold War d*ck measuring contest.

[magnemoe]

2 hours ago, DerekL1963 said:

Same reason they didn't care in the 70's, 80's, or 90's - people don't care about space.  Has nothing to do with any other hand waving or smoke blowing BS.  People don't care about space.  Despite decades of mythmaking, they only barely cared in the 60's...  and that was only about a Cold War d*ck measuring contest.

True, but the 2000's was an lull, this changed with SpaceX, if not for them someone else would come but later. 

[kerbiloid]

1 hour ago, magnemoe said:

this changed with SpaceX

So, PR decides.

[Jacke]

On 10/25/2023 at 6:26 AM, SunlitZelkova said:

Why didn’t anyone care about spaceflight in the 2000s?

 

On 11/11/2023 at 12:49 AM, DerekL1963 said:

Same reason they didn't care in the 70's, 80's, or 90's - people don't care about space.  Has nothing to do with any other hand waving or smoke blowing BS.  People don't care about space.  Despite decades of mythmaking, they only barely cared in the 60's...  and that was only about a Cold War d*ck measuring contest.

I was there for most of space exploration (my earliest space memory is watching the re-entry of Gemini 12) and I have to at least partly agree with you.

You take any course on introducing new things to business and they'll talk about those new things, especially new technologies, needing champion(s).  There's a reason Robert Heinlein wrote a story about a businessman drumming up support for going to the Moon and called it "The Man Who Sold the Moon".  It has to be sold and resold as an idea, as a collection of projects that need support.

(Don't even consider Elon Musk.  Look at what he did with Twitter.  Find the real story about other things he's done.  Like this one.)

When getting into space was linked to international competition, it was an easier sale.  I remember Isaac Asimov writing about the launch of Sputnik 1 and how it galvanised him into writing much more fact articles and books for the new era.

However, don't completely worry about this.  If it's possible, the impact of another major achievement by China will certainly have some reaction.  Like landing on the Moon.  Hopefully the reactions will be useful ones.

[darthgently]

3 hours ago, Jacke said:

Don't even consider Elon Musk.  Look at what he did with Twitter.  Find the real story about other things he's done.  Like this one.)

Discussed in another thread.  Accident rates at SpaceX  are no higher than heavy manufacturing in general.  Silly to compare bespoke very low production rates at other space contractors to a rocket factory assembly line.

As for Twitter/X, it is growing and making more money than when he bought it with advertisers on board and increasing.  It didn't die at the multiple predicted points in the past

I only bring it up because you did

[darthgently]

On 10/25/2023 at 2:26 AM, SunlitZelkova said:

Why didn’t anyone care about spaceflight in the 2000s?

I remember at the time seeing the Space Shuttle + ISS era as a politically determined effort to counter the divisions created during the space race and to encourage an attitude of international cooperation after the fall of the USSR (and somewhat to present a challenge to cooperate or not to the PRC).  I think this would have continued if the shuttle had been more cost effective and the shuttle losses had not occurred.

[JoeSchmuckatelli]

On 11/10/2023 at 8:49 AM, kerbiloid said:

NASA was paying because it had reasons to pay

 

On 11/10/2023 at 10:54 AM, DDE said:

I think that's half the story. They wouldn't have gotten the extra money otherwise if they hadn't invented such a beautiful excuse.

Oh very much so.  @kerbiloid- you have seen our Congress, yes?  

[kerbiloid]

5 hours ago, JoeSchmuckatelli said:

@kerbiloid- you have seen our Congress, yes?  

Weekly. They have a nice coffee-shop in the lobby.

[StrandedonEarth]

Okay, here's one: is there any dV bonus to be gained by launching to polar orbits from higher and higher latitudes? I'm thinking there's less and less rotational velocity to counter, but as the Earth flattens toward the poles, the launch site sinks deeper into the gravity well, and the denser air that accompanies it which increases drag and reduces thrust/ISP.

Sounds like an interesting mental exercise that I have no time for, never mind the necessary formulae and data.

Edited November 16, 2023 by StrandedonEarth

[JoeSchmuckatelli]

On 11/15/2023 at 9:47 PM, StrandedonEarth said:

the launch site sinks deeper into the gravity well

I looked at sea-level weight vs mountain weight a long time ago and the difference is tiny - quick google shows a New York Times article that a person who weighs 150lbs at sea level (New York Hipster Male?) would only weigh 149.92 lbs at 10,000 feet.  So not thinking there's a gravity disadvantage to your scenario.

We've also previously discussed the advantages (or not) of dedicated rail / onsite construction at the equatorial Andes vis-a-vis atmosphere pressure & etc. and IIRC, it was a negligible savings.  

(Cannot math you an answer - but perhaps good enough?)

[mikegarrison]

On 11/18/2023 at 9:34 AM, JoeSchmuckateli said:

I looked at sea-level weight vs mountain weight a long time ago and the difference is tiny - quick google shows a New York Times article that a person who weighs 150lbs at sea level (New York Hipster Male?) would only weigh 149.92 lbs at 10,000 feet.  So not thinking there's a gravity disadvantage to your scenario.

We've also previously discussed the advantages (or not) of dedicated rail / onsite construction at the equatorial Andes vis-a-vis atmosphere pressure & etc. and IIRC, it was a negligible savings.  

(Cannot math you an answer - but perhaps good enough?)

Radius of the Earth is more than 6000 km. Even an 8km mountain peak is thus about 0.12% different in height versus sea level. This is why gravity is essentially the same.

[Shiki404]

Hello Everyone, I'm new in this forum. And I have something to ask

Does a G-force inflicted upon person's body correspondent to the mass of the vehicle itself? For example, a car and a warship moves at the same speed, before suddenly making a sharp turn to the left (same turn angle at the same same speed).  Assuming the person is in seated position inside the car and a warship, does the one on warship experience much more G-force than the one on the car?

Thank you for reply

[Vanamonde]

8 minutes ago, Shiki404 said:

Hello Everyone, I'm new in this forum. And I have something to ask

Does a G-force inflicted upon person's body correspondent to the mass of the vehicle itself? For example, a car and a warship moves at the same speed, before suddenly making a sharp turn to the left (same turn angle at the same same speed).  Assuming the person is in seated position inside the car and a warship, does the one on warship experience much more G-force than the one on the car?

Thank you for reply

The force on the vehicle is stronger. The force on the passenger is the same. And welcome to the forum.

[Shiki404]

5 hours ago, Vanamonde said:

The force on the vehicle is stronger. The force on the passenger is the same. And welcome to the forum.

Thanks for the answer. Does that also mean the higher the vehicle's mass, the higher the stress inflicted upon the vehicle, the higher the G-force is?

[Hotel26]

6 hours ago, Vanamonde said:

(same turn angle at the same same speed)

the acceleration on all 3 (car, warship and person) is identical.  The force applied is greater for the warship than the vehicle (proportional to mass of each) -- and, in each case, a small component of the force applied to/by the car and vehicle is transmitted to the person, in proportion to the mass of the person.

1 hour ago, Shiki404 said:

Thanks for the answer. Does that also mean the higher the vehicle's mass, the higher the stress inflicted upon the vehicle, the higher the G-force is?

Actually, no, and one has to understand now the term "G-force".  [The first two terms (mass, 'stress') are related, but not the third, when acceleration is the same: "same turn, same speed".]

So assuming that the "same turn, same speed" is constant, but we are increasing the mass of the vehicle -- and considering F = m . a -- same turn/speed requires the same acceleration, so F (force) will have to increase linearly with m (mass).  The force applied to the person will be the same, because the person's mass is still the same.

Because it is hard for a person to think in terms of the acceleration applied, and because they feel this as heaviness or weight, especially in the common case of fighter pilots or F1 drivers, the standard, useful comparison is by weight and this is not only related to your mass but also the Earth's gravitational field.  It's only a comparison and the G-force you mention is not in this case nor usually due to gravitational force.  Gravitational force is the pull of the Earth or any body with significant mass, but G-force is expressed as an acceleration, e.g. 9.8 meters per second per second, which has the mass factored out and is just a standard acceleration.

Maybe this will help.  A conventional airplane flying level at constand speed in a 30-degree bank will execute a standard Rate-1 turn (180 degrees in 1 minute).  "G force" will feel slightly higher than in straight  & level flight.  In a 60-degree bank, G-force will be 2 G's and be very noticeable.  This is a Rate 2 turn (360 degrees per minute).  You will find this very noticeable!  And this does not depend upon your weight on the bathroom scales or the type of equipment.

There is technically a gravitational force, but whenever you usually hear the term G-force, it will be referring to the acceleration applied -- not only by gravity -- but very often any kind of acceleration being measured by this useful yardstick.  it is often abbreviated to "G's", which is maybe less confusing.

Edited November 20, 2023 by Hotel26

[magnemoe]

15 hours ago, Shiki404 said:

Hello Everyone, I'm new in this forum. And I have something to ask

Does a G-force inflicted upon person's body correspondent to the mass of the vehicle itself? For example, a car and a warship moves at the same speed, before suddenly making a sharp turn to the left (same turn angle at the same same speed).  Assuming the person is in seated position inside the car and a warship, does the one on warship experience much more G-force than the one on the car?

Thank you for reply

Hotel26 Described it very well but its an other issue with an ship, it will tilt under rapid turns making the turn feel much more and who higher you are the more strong it would feel. 
Being on the bridge of an WW 2 aircraft carrier maneuvering as crazy to avoid dive bombers or torpedoes would not be pleasant  but not very noticeable down in the engine rooms. 

[SunlitZelkova]

1. Would a different Space Shuttle design being selected allow a higher flight cadence? I’m specifically trying to see if it was ever possible for a Space Shuttle to launch once a week (different shuttles obviously).

2. What would the failure modes for an inertial confinement fusion engine look like? Could it ever explode, and would it be big?

3. Here’s a big one. What are the basic formulas I would need to know to do a very rough design of my own space mission?

[kerbiloid]

1. The engine and tile refurbishment.
The engine (of the 2nd stage) could not be simpler or cooler. Also, the engine assemblies were shared between the shuttles, so it was actually a lego shuttle.
The hull could be made of titanium, and the heatshield could be solid rather than tiled.
So, unlikely the engine check&repair could be faster. Same about the cadence.

[monophonic]

12 hours ago, SunlitZelkova said:

3. Here’s a big one. What are the basic formulas I would need to know to do a very rough design of my own space mission?

I couldn't find it now, but when I played KSP1 a lot I had a spreadsheet to plan my missions. I used dV maps calculated by others and the rocket equation to calculate the dV available in my designs. So rocket equation and those to calculate the dV requirements for transfers should get you far.

[tomf]

The Vis-viva equation https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://en.m.wikipedia.org/wiki/Vis-viva_equation&ved=2ahUKEwjNga-h4NeCAxV0VUEAHWH3B_oQmhN6BAgXEAI&usg=AOvVaw3liegRUJSyyy2Os4MBYXOf

will get you almost everything you might want. E.g. to calculate the DV to go from a 100km orbit to a 200 km orbit you would use the equation to calculate your velocity for the 100km orbit, again to calculate the velocity for the 100x200 when the craft is at 100 orbit. The difference is the DV for the first burn. Repeat for the 200km orbit for the second burn.

[Shiki404]

Does the amount of colonist needed different between planetary-based colony and orbital-based space colony? Assuming the necessities such as food, life support, basic services and healthcare etc. is already fulfilled, what's the minimum amount of colonist needed in order to create a stable and growing population?

Edited November 23, 2023 by Shiki404

[monophonic]

2 hours ago, Shiki404 said:

Does the amount of colonist needed different between planetary-based colony and orbital-based space colony? Assuming the necessities such as food, life support, basic services and healthcare etc. is already fulfilled, what's the minimum amount of colonist needed in order to create a stable and growing population?

(TL;DR: No.) The question of minimum viable population (use this as your search term) doesn't seem to have a single clear cut answer. For a short-ish period, whatever may count as short-is, as little as fifty individuals might suffice. For very long term i.e. from here on out to eternity, the estimates seem to hover around a few thousands. Ten thousand seems like a safe-ish bet.

The long term threats are major catastrophies and inbreeding. The population doesn't all have to live in the same physical colony as long as there is sufficient movement between the individual habitats to keep their gene pools effectively combined. Dividing the population to multiple habitats also helps protect against catastrophies, if there are enough survivors even if a meteor strike takes out an entire habitat and its inhabitants. Active measures such as that icelandic "cousing detector app" or even genetic testing can help prevent inbreeding depression (another search term). The testing comes with a hefty can of worms raising questions of moral nature, though.

So, assuming everything else is truly equal, the required population numbers are equal. If one type has e.g. better radiation protection, there may be minor differences for shorter periods of isolation. Long term I expect those to disappear into the noise.

https://en.wikipedia.org/wiki/Minimum_viable_population