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MoreGull OP t1_ja8q1zp wrote

I mention Callisto specifically as I think it is a far better prospect than Mars. And the only advantage the Moon has is proximity to Earth.

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chirop1 t1_ja8srtd wrote

The moon is a training ground

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lochlainn t1_ja9bry2 wrote

Definitely.

The moon will probably be our orbital industry hub or downtime location long term; we just don't know enough about the interaction with lower gravity yet.

If we can survive on a more or less permanent basis at lunar gravity, it's easier to base there for orbital work: shallower gravity well with no atmospheric drag and closer geostationary orbit for less control lag. Remote work and even shift crews from the moon to lunar orbit make much more sense than from the bottom of Earth's gravity well.

If lunar gravity isn't sufficient for the human body over the long term, it'll still extend our ability to stay in space. We'll just need more crews and more energy to turn them over faster.

And in either case, lunar water and metals will probably be the first source of significant orbital construction material we tap.

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MoreGull OP t1_ja9cjxr wrote

Why the moon at all?

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lochlainn t1_ja9g620 wrote

Because that proximity advantage, for the bootstrapping phase of orbital industry, is enormous.

Like the previous poster said, the moon is going to be our training ground. But it's also more than that. It's an entire orbital mine with a low orbital Delta V requirement. Lunar orbit is much less expensive to achieve from the surface than Earth orbit. Remote orbital processing will have far less signal lag. Sending crews up in shifts and rotating them down for in-gravity recovery is a fraction of the price it would be to Earth.

We know that microgravity is ultimately catastrophic to humans. We don't know how much gravity it takes to remediate or prevent the damage.

So the moon gives us the perfect, "low" effort testbed. Without the knowledge we can only get on the moon (gravity effects, how to build safe living structures using native materials, how to build low-energy processing facility in low gravity, how to maintain a long term closed ecology of food, waste, and heat), we'd be going into any longer term missions blind.

There are only 3 options for orbital industry; haul it up from Earth, get it from the moon, or get it from a near Earth asteroid.

Near Earth asteroids are, until we develop the capability to actually alter their orbit, effectively a remote deep space mission with pass/fail criticality. There's nothing we could learn from one that we can't learn from the moon, while learning everything else already mentioned at the same time.

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MoreGull OP t1_ja8tvdu wrote

Indeed. I think that's its main role for us, other than dedicated scientific pursuits.

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Fortissano71 t1_ja99mht wrote

The moon is the tutorial. Once unlocked, we can move on to the higher levels with greater dangers and distances. /s

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MoreGull OP t1_ja99xyq wrote

We can still build our orbital infrastructure.

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ObviousGazelle t1_jaaiwqt wrote

You forget mars has an atmosphere. Thin, but it's there. The question when choosing the two will be this: Can humans build radiation shielding good enough to live permanently on Mars, and of not then what are the trade offs because Callisto has no atmosphere for aerobraking... So which challenge is solvable first?

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Hosni__Mubarak t1_jab4b0g wrote

Can’t you use the orbital mechanics of Jupiter to aerobrake yourself?

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MoreGull OP t1_jaaj5ce wrote

Indeed. Another reason to skip Mars entirely.

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