Reasons to not implement gravity on ISS ?

[zapatos]

2 hours ago, swansont said:

The ISS is not shaped like that

Thank you. It was only an analogy. I didn't actually think the ISS was shaped like a fan. I was trying to point out that if the axis of rotation is pointing at the sun then you do not need to have shielding on all sides of the craft.

[swansont]

13 hours ago, zapatos said:

Thank you. It was only an analogy. I didn't actually think the ISS was shaped like a fan. I was trying to point out that if the axis of rotation is pointing at the sun then you do not need to have shielding on all sides of the craft.

But the thread is about the ISS, so we are discussing the ISS geometry. 

[zapatos]

2 hours ago, swansont said:

But the thread is about the ISS, so we are discussing the ISS geometry. 

The OP specifically said: 

"I meant an 'end?'  module at ISS, not the whole thing..."

"Perhaps only a 10m diametre attached  'wheel'"

Why would a 10m diameter attached wheel, rotating such that its axis of rotation faces the sun, need shielding on all sides?

[swansont]

3 hours ago, zapatos said:

The OP specifically said: 

"I meant an 'end?'  module at ISS, not the whole thing..."

"Perhaps only a 10m diametre attached  'wheel'"

Why would a 10m diameter attached wheel, rotating such that its axis of rotation faces the sun, need shielding on all sides?

The ISS has solar panels which preclude that alignment.

[zapatos]

Quote

The ISS has solar panels which preclude that alignment.

You are pretty slippery.

On 9/23/2019 at 10:37 AM, swansont said:

Doesn’t that question answer itself? i.e. it’s spinning? 

You said here that "it" is spinning and implied that "spinning" is the reason you could not have a shielded side face the sun.

What is it about "spinning" that prevents having only a shielded side face the sun.

Edited September 24, 2019 by zapatos

[swansont]

5 hours ago, zapatos said:

You are pretty slippery.

You said here that "it" is spinning and implied that "spinning" is the reason you could not have a shielded side face the sun.

What is it about "spinning" that prevents having only a shielded side face the sun.

The geometry of the ISS, and the need to keep all of the solar panels facing the sun.

[zapatos]

46 minutes ago, swansont said:

The geometry of the ISS, and the need to keep all of the solar panels facing the sun.

So the geometry of the ISS requires that all sides of the ISS be shielded while it is spinning. Got it.

[Sensei]

On 9/23/2019 at 4:46 PM, mistermack said:

Once you leave the Earth's magnetic shield, you would need to provide some all-round shielding for a spinning craft, against the worst solar storms. If it's not spinning, then you could presumably concentrate the protection on one side and turn that towards the Sun till the worst is over.

According to wiki :  "A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured,^[14] giving astronauts as little as 15 minutes to reach shelter." and " Anyone who had been on the Moon's surface during a particularly violent solar eruption in 2005 would have received a lethal dose."  ^[24]

Spaceships for shielding against high energy particles use tanks with water and ammonia. They have couple use.

[Janus]

On 9/24/2019 at 6:55 AM, zapatos said:

The OP specifically said: 

"I meant an 'end?'  module at ISS, not the whole thing..."

"Perhaps only a 10m diametre attached  'wheel'"

Why would a 10m diameter attached wheel, rotating such that its axis of rotation faces the sun, need shielding on all sides?

The ISS orientation is such that it always keeps one side always facing the Earth.  This is so that the antennae always always pointed in the right direction, the windows point at the Earth, debris shielding can be arranged to be thickest in the direction of greatest risk, etc.  Now if you try and add a section that rotates so that its axis always points towards the Sun, you can't do this.  In addition, Since the Earth itself orbits the Sun, the axis of this rotating section would have to be changed over the course of a year in order to keep it pointing towards the Sun ( otherwise, shielding pointing at the Sun in July would be pointing away from it in Dec.), which introduces precession issues.  Then there is the issue of dealing with changes of angular momentum and balance as people and equipment move in and out and around the rotating section, the mass of such a section would need to be significant to minimize these effects, or you would need some kind of active compensation with a system of sensors, computers and movable counterweights, all working together to keep things in balance.

[zapatos]

1 hour ago, Janus said:

The ISS orientation is such that it always keeps one side always facing the Earth.  This is so that the antennae always always pointed in the right direction, the windows point at the Earth, debris shielding can be arranged to be thickest in the direction of greatest risk, etc.  Now if you try and add a section that rotates so that its axis always points towards the Sun, you can't do this.  In addition, Since the Earth itself orbits the Sun, the axis of this rotating section would have to be changed over the course of a year in order to keep it pointing towards the Sun ( otherwise, shielding pointing at the Sun in July would be pointing away from it in Dec.), which introduces precession issues.  Then there is the issue of dealing with changes of angular momentum and balance as people and equipment move in and out and around the rotating section, the mass of such a section would need to be significant to minimize these effects, or you would need some kind of active compensation with a system of sensors, computers and movable counterweights, all working together to keep things in balance.

Thanks. I appreciate the detailed explanation. 

[zapatos]

6 hours ago, Janus said:

The ISS orientation is such that it always keeps one side always facing the Earth.  This is so that the antennae always always pointed in the right direction, the windows point at the Earth, debris shielding can be arranged to be thickest in the direction of greatest risk, etc. 

Can you tell me how they keep one side of the ISS always facing the earth, but the solar panels always facing the sun? I assume that means that the solar panels make roughly one full rotation per day relative to the rest of the space station as that portion remains pointing at the earth.

[Janus]

14 minutes ago, zapatos said:

Can you tell me how they keep one side of the ISS always facing the earth, but the solar panels always facing the sun? I assume that means that the solar panels make roughly one full rotation per day relative to the rest of the space station as that portion remains pointing at the earth.

They are mounted on gimbals to keep them orientated towards the Sun, but they don't make a full rotation.  The ISS orbit takes it through the Earth's shadow. So the panels rotate to follow the Sun for that part of the orbit, and then while in shadow, they just rotate back in order to be ready catch the Sun at the next sunrise.   60% of the electricity produced is used to charge the batteries to get them through the period when the Sun is eclipsed by the Earth