For Questions That Don't Merit Their Own Thread

[K^2]

6 hours ago, magnemoe said:

Now I wonder that will happen if you have another loadout than 2 drop tanks? 
Yes its pretty simple to test for and its not like you will wash it with live weapons anyway. 

IIRC, the flight computer is aware of the loadout and can make conditional corrections to, e.g., fly-by-wire. So it should be pretty straight forward to set up a protocol where the ground station queries it and adjusts IK constraints based on dimensions of anything attached to hardpoints. It is a solved problem in CNC used in manufacturing, so I would like to imagine that whatever system the AF is using is at least as competent as a 10 year old 6DoF CNC cutter.

[SOXBLOX]

The article says they plan to use this for a lot more. De-painting and repainting, and working with larger aircraft.

[SpaceFace545]

So what do y'all think the dynamics are gonna look like on the space station as Starliner and DreamChaser look to be operational by next year. Will these two replace spacex's spacecraft or will it be a mix of all 4?

[JoeSchmuckatelli]

45 minutes ago, SpaceFace545 said:

So what do y'all think the dynamics are gonna look like on the space station as Starliner and DreamChaser look to be operational by next year. Will these two replace spacex's spacecraft or will it be a mix of all 4?

I would guess a mix. 

Adding lift capacity is likely to just expand the market rather than replace existing 

[SOXBLOX]

1 hour ago, SpaceFace545 said:

So what do y'all think the dynamics are gonna look like on the space station as Starliner and DreamChaser look to be operational by next year. Will these two replace spacex's spacecraft or will it be a mix of all 4?

First, we hope there's an operational station up there by next year. 

Edited May 6, 2021 by SOXBLOX

[kerbiloid]

All three (and Soyuz) will be competing for pax.

[KSK]

On 5/6/2021 at 7:12 PM, SpaceFace545 said:

So what do y'all think the dynamics are gonna look like on the space station as Starliner and DreamChaser look to be operational by next year. Will these two replace spacex's spacecraft or will it be a mix of all 4?

Mix of all four, exact mix depending on which vehicles are contracted for which flights and, pessimistically, which vehicles or their launchers are suffering any issues that would prevent them from flying.

In the longer term, I suppose it would be possible for Starliner/Dreamchaser to completely supersede Crew Dragon but neither of them are designed as cargo vehicles (as far as I know), so there’ll be a space in the roster for Cargo Dragon for a while yet, I think.

 

[SpaceFace545]

How would a space elevator cable be brought to the surface of earth or from earth to the counterweight. I doubt you could attach a cable to rocket and just rendezvous with a cable just dangling, and I don’t know if a cable could just “drop” from space. So how would it work?

[JoeSchmuckatelli]

I asked a similar question quite a few pages back - and came away with the impression that it's just not feasible. 

[SpaceFace545]

8 minutes ago, JoeSchmuckatelli said:

I asked a similar question quite a few pages back - and came away with the impression that it's just not feasible. 

A lunar climber makes sense but atmospheric drag seems to ruin its feasibility on earth.

[kerbiloid]

The lunar one makes even less sense, because almost all lunar orbits are instable, except of the "frozen" ones,

Quote

 Four frozen lunar orbits have been identified at 27°, 50°, 76°, and 86° inclination. NASA expounded on this in 2006:

, and none of them is equatorial.

***

Probably, they could either plant a beanstalk to climb, or train an orbital silkworm to get down.
Maybe both.

***

Wait... A silkworm...

And China just launched a station...

And they rejected the suggestion to move it farther from the equator...

And they are running the Belt and Road project...

Oh, my ....

[tomf]

6 hours ago, SpaceFace545 said:

How would a space elevator cable be brought to the surface of earth or from earth to the counterweight. I doubt you could attach a cable to rocket and just rendezvous with a cable just dangling, and I don’t know if a cable could just “drop” from space. So how would it work?

I think the usual plan has it being lowered down from geostationary orbit. If you keep the centre of mass at the right height then it will remain stationary relative to earth's surface. Because it isn't moving you can just continue down into the atmosphere until you got the ground, no re-entry heating or anything.

There well be problems with the cable  having angular momentum, spinning but those will have to be solved well before it is long enough to get to the atmosphere.

[DDE]

In the wake of April's climate summit, the Russian oil and gas bigwigs have discovered the existence of the gas "hydrogen", and are plugging it everywhere. One of the several ideas they've had thus far is using the piplines currently exporting (effectively) methane to export hydrogen, produced through environmentally palatable means (e.g. pyrolysis and carbon capture using nuclear heat).

My question is mostly a physics one: given the ridiculously low density of gaseous hydrogen (LH is likely out) can a sufficient amount of it be conveyed using extant infrastructure to provode for the same amount of joules per annum?

[kerbiloid]

5 hours ago, DDE said:

My question is mostly a physics one: given the ridiculously low density of gaseous hydrogen (LH is likely out) can a sufficient amount of it be conveyed using extant infrastructure to provode for the same amount of joules per annum?

(In Russian, pdf)
https://cyberleninka.ru/article/n/transportirovka-vodoroda

Currently Americans arre doing so, though it's limited with several regions.

[DDE]

26 minutes ago, kerbiloid said:

(In Russian, pdf)
https://cyberleninka.ru/article/n/transportirovka-vodoroda

Currently Americans arre doing so, though it's limited with several regions.

4.6x energy expenditure to push it, significant losses (20-30%). But sinze it's a Gazprom study they still deem it acceptable )

[kerbiloid]

  

24 minutes ago, DDE said:

4.6x energy expenditure to push it, significant losses (20-30%).

Afair, ~30% of natural gas is also spent to blow the other gas through the pipes,

Iirc, in the S.Eygenson's "Без нефти" / "Without oil" essay

Edited May 13, 2021 by kerbiloid

[K^2]

On 5/12/2021 at 11:48 PM, DDE said:

My question is mostly a physics one: given the ridiculously low density of gaseous hydrogen (LH is likely out) can a sufficient amount of it be conveyed using extant infrastructure to provode for the same amount of joules per annum?

You'd be moving a smaller mass but a larger volume. I also expect hydrogen gas to have more viscosity at the same temperature, since lighter molecules are going to diffuse faster. So you are going to have a significantly higher pressure differential at higher flow velocity, and that means a lot more energy consumed pushing the gas through the pipe, but more importantly, it will require the pumping stations to be able to handle the higher pressure and power requirements.

This might also put a limit on how far you can push gas along a given pipe, since they are rated to a specific pressure. So if the pressure differential has to be higher, some pipelines that are close to the limit might become overpressurized with hydrogen unless you subdivide the length and put additional pumping stations in the middle.

This is definitely not a case of, "We'll just swap out the gas and everything will work." Some amount of retrofitting will have to be done.

Hydrogen also leaks and ignites a lot easier, so there will be more accidents, further increasing costs. Whether that's significant, I don't know, but something to consider for sure.

[kerbiloid]

The ferrofluid fluid.

You want it.

Spoiler

 

 

[ARS]

Back then on 1997, Progress M-34 crashed with Mir's Spektr module and causing a depressurization breach that forced the crew to seal the module and isolate it from the remainder of Mir station for the rest of station's life. What would people do if such an event happened on modern space station such as ISS (collision outside the station that caused one or more module to depressurize that necessitates it to be sealed from the rest of the station), are we leaving it like that for the rest of the station's lifespan? Are we going to detach and deorbit it (a dead module is essentially a dead weight for stationkeeping thruster right?) before replacing with new ones? Or the space technology has advanced enough from Mir era that we can now attempt to repair and restore the module?

[K^2]

That's the sort of thing they'll have to evaluate on a case-by-case. Some modules might be worth getting rid of, while others are easier to just keep around. It's not about weight, after all, but about drag, so there are a lot of places you can put a dead module where it won't make a big difference. Same deal for repairs. A puncture's easy to fix. But if the module was partially crushed by impact, it's probably too much risk. A module that might pop a seam at any moment is not worth keeping pressurized.

I think, the biggest change from Mir, in part due to this accident, is how the cables between modules are managed. They had to sever them by hand when Spektr sprung a leak, cutting some of them IIRC, and that very nearly resulted in having to evacuate much, if not all of the station. I'm pretty sure ISS doesn't have anything you can't disconnect on a spot to shut a hatch. On the other hand, I haven't seen anything that looks like it might shut automatically. So if there is more serious damage completely exposing a section to the vacuum, I don't know if anyone would have time to do anything about it. Maybe somebody more familiar with ISS can correct this.

Edited May 16, 2021 by K^2

[DDE]

11 hours ago, ARS said:

Back then on 1997, Progress M-34 crashed with Mir's Spektr module and causing a depressurization breach that forced the crew to seal the module and isolate it from the remainder of Mir station for the rest of station's life. What would people do if such an event happened on modern space station such as ISS (collision outside the station that caused one or more module to depressurize that necessitates it to be sealed from the rest of the station), are we leaving it like that for the rest of the station's lifespan? Are we going to detach and deorbit it (a dead module is essentially a dead weight for stationkeeping thruster right?) before replacing with new ones? Or the space technology has advanced enough from Mir era that we can now attempt to repair and restore the module?

Spektr was partially salvaged by performing an indoors EVA and replacing its bulkhead door with one that could admit power cables, since its four solar arrays were of considerable value. Add to it any externally-mounted consumables stores (e.g. TKS-style fuel tanks) and a vented module can have its uses.

Edited May 16, 2021 by DDE

[YNM]

Not a question, but definitely a rabbit hole of interesting things : narrowly avoiding accidental burns, trying to reanimate animals, and Raytheon making microwave ovens (and still remains on one nuclear ship)...

 

Edited May 17, 2021 by YNM

[Admiral Fluffy]

How would you make a deflector shield?

Besides having a giant wall of metal in front of you.

Edited May 17, 2021 by Admiral Fluffy

[Spacescifi]

2 hours ago, Admiral Fluffy said:

How would you make a deflector shield?

Besides having a giant wall of metal in front of you.

 

This has been answered elsewhere on the web, but  I will tell you anyway.

 

You have finite KNOWN options.

What are you trying to deflect in space?

Magnetic fields deflect plasma and charged particles. Nothing else really I know of unless it's magnetically polarized metal which you are unlikely to encounter anyway.

You can laser burn stuff with a laser, which turns stuff into mini rockets.

 

Deflect is to move out the way, and over you or around you. Not into you. Not like scifi where stuff slams into the shield bubble and disintergrates.

Edited May 17, 2021 by Spacescifi

[magnemoe]

58 minutes ago, Spacescifi said:

 

This has been answered elsewhere on the web, but  I will tell you anyway.

You have finite KNOWN options.

What are you trying to deflect in space?

Magnetic fields deflect plasma and charged particles. Nothing else really I know of unless it's magnetically polarized metal which you are unlikely to encounter anyway.

You can laser burn stuff with a laser, which turns stuff into mini rockets.

Deflect is to move out the way, and over you or around you. Not into you. Not like scifi where stuff slams into the shield bubble and disintergrates.

The typical scifi shield is fantasy, you can use magnetic field to deflect charged particles.  You can use lasers or anti missiles to break up incoming warheads. Yes you got fragments who you have to evade or be armored to handle. If you are an static space station you could put an asteroid above you, now your main issue is that your sensors and close in weapon systems are still vulnerable unless the defenses are on mobile ships around the station.