There's still a lot of defense reasons to go to the moon. You can put much larger telescopes there, though you're back to windows of time you can look at a location but you can have good will and dedicate time to scientists. Though they might not want to reveal the resolution even though this can be roughly back tracked through size. There's also the weapons incentive even though that's illegal. But if you're able to cheaply and consistently put people on the moon then you clearly have the resources to cheaply put large rods of tungsten in orbit (good luck responding to), being able to take out enemy satellites (nav, surveillance, missile launch detection, etc), replace/upgrade satellites quickly, etc. The Apollo missions were always about how much payload you could put in orbit.
It's also beneficial if you want to start space mining, really essential for that actually.
Putting a spy telescope on Moon seems like a bad idea.
- Moon moves across the sky very slowly (relative to stars) which means that your spy satellite would have about 30 days to cover full earth, and would be able to see only a part of Earth at any given moment (theoretically half, but lot of it would be from very bad angles)
- Moon is in an ecliptic? orbit, so spying on anything close to the poles will be from an angle - this might not be bad in all cases but the lack of flexibility is a big thing
- Putting any mass on the Moon requires much more delta V than putting something in orbit. If you can put a big telescope on Moon, you can put several in Earth orbit or put one much bigger one.
Having capability to stage on the Moon would be interesting, especially if fuel can be made on the moon. It would be easier on human bodies and you have access to lot of resources. If you can find water and decent metals, that's a pretty good spot to fuel your rockets.
The moon moves slowly but the Earth rotates quickly. Most of the earth surface can be seen during one day. The earth is not illuminated by sunlight all the time, about half of the lunar month would be completely dark.
Moon is in an inclined orbit, which is slightly elliptic. I assume this is what you meant by "ecliptic" (which refers to the orbital plane of the Earth around the Sun). The orbital inclination has the most significant implications to Earth surface visibility, but the Moon is far enough that almost half of Earth surface is visible at all times.
For Earth observation, satellites are better positioned than a lunar surface observatory.
The moon isn't a great place for an outpost or staging point for exploration. Launches and descents are expensive and spoil all the savings. Maybe if LH2/LOX could be manufactured on the moon very cheaply (from water ice), it could make sense to do refueling for exploration vehicles parked on a halo orbit near Lagrange points.
But orbital refueling of cryogenic propellants (especially hydrogen) or manufacturing them on the moon aren't viable in the near future.
There aren't a lot of good economic or exploration incentives to go to the moon, unfortunately. It only has scientific and prestige value. The long lunar night (14 earth days) makes it a poor location for a permanent outpost.
All of that said, I'm all for going to the moon with humans on board.
You are right about Earth rotating. I spaced out on that one.
About the ecliptic, I was trying to say that any observatory on the moon would have issues observing polar regions because the Earth surface in polar regions would be at a low angle. I know some spy sats "look ahead" to get better detail resolution but they have ability to look from different angles as well. Moon would be a bad spot for that.
Rest of it I mostly agree. One thing up to debate is whether an outpost on the moon would be useful. If you can manufacture fuel on the Moon, it would be very useful. Another aspect is human health in zero G. Moon with low gravity may be enough to help with long term human stay.
The lunar orbit is inclined so that the moon moves between about +/- 28 degrees north/south latitude with reference to the Earth equatorial plane.
That's Earth's axial tilt of ~23 deg + the inclination of the lunar orbit w.r.t. the ecliptic of ~5 deg.
This means that when the moon is at its northest (above southern Florida), it has a pretty good view over the north pole (but it's at quite an oblique angle of ~60 deg), and the south pole is not visible. About 14 days later it's the opposite.
But yeah, I agree with the conclusion that the Moon is not a good place for a Earth observation for a lot of reasons.
>being able to take out enemy satellites (nav, surveillance, missile launch detection, etc)
You can easily do it without having objects in orbit. You can simply launch a ballistic cloud of debris at suborbital speeds and kinetic energy of the targeted satellite will do the rest. Time to hit could be shorter for an orbital system, but not significantly so. This is why I consider the recent news about the Russian orbital satellite killer to be a cheap fearmongering.
There have been studies and the rods from the gods concept doesn’t work. Atmospheric braking would slow them to their terminal velocity before impact. You might as well throw them out of a plane. There are also all kinds of problems with time to target, terminal guidance and cross range capability.
All of what you said can better be done by machines and many such things are done by machines.
The milestones that get people existed are when men reach places hitherto unreached, but there is no practical purpose to risking the life of a man who needs far more complicated facilities to survive, other than bragging rights.
The I.S.S. was largely a political and not a scientific endeavor, and it's a shame it consumed so many resources, that could have gone to more serious scientific efforts.
The cost of the I.S.S. could have easily given mankind nuclear fusion, — the ability to power entire countries with a couple of litres of seawater. It's strange where priorities lie.
There's no proof of this because viable nuclear fusion has not yet been achieved. Humanity may never achieve this for all we know (though I sincerely hope we do).
The same can be said about any research whereto resources are allocated.
Making a reasonable estimate when both started, nuclear fusion seems to be a smarter investment, for if it finally be there, the benefits are incalculable.
We have nuclear fusion, both from the sun and here on Earth (ITER, NIF, H-bombs). The main problems with human-started nuclear fusion are that (so far, iirc) it consumes more energy than it produces, and we cannot sustain it for a long time.
"The benefits" are currently very calculable, and direct economics of nuclear fusion is very negative. (The research benefit is unique though.)
For nuclear fusion to be of incalculable benefit to mankind, we need insanely small nuclear fusion that is energy-positive and sustainable in a simple way. "Insanely small" means smaller than Moon-sized, when we know that Jupiter-sized is too small/light in nature.
Sustained nuclear fusion for energy generation still faces daunting challenges.
It's also beneficial if you want to start space mining, really essential for that actually.