The sun was 12" diameter. Earth was the head of a pin, and we hiked the better part of a mile to place Neptune, a small bead. I always "knew" that the solar system was large and mostly empty, but there's something really eye opening when making your kids hike for 10 minutes between placing pieces of your scale model!

Our best global elevation model for Mars is MOLA, at 463 metres per pixel. The Moon is better, 118 m, and about 59 m where LOLA and Kaguya overlap. Mercury we barely have at all - for practical purposes, a photograph.

Which means that for every body we talk about settling, everything smaller than a football stadium is unknown. Not poorly mapped. Unmeasured.

I keep thinking about what that means for a first landing party. You would arrive with a map good enough to choose a region and useless for choosing a spot. Boulder fields, metre-scale slopes, ground that is soft or hard, a crack you cannot drive across - none of it is in the data. You would find out by looking, and looking costs fuel and time and risk.

Some consequences I find interesting:

- Site selection would be provisional rather than planned. You pick a hundred square kilometres from orbit, then spend a long time finding the actual hectare.

- The first really valuable export from a colony might be survey data. Not ore, not power - just knowing what the ground is like.

- Rovers stop being transport and become instruments. Their job is to reduce uncertainty, not to move mass.

- Anything that needs precision - landing pads, rail, buried habitat - has to wait for local survey that no orbital mission can give you.

My doubts now: would a serious effort simply accept this and plan for a long survey phase on arrival, or would it be worth flying a dedicated high-resolution mapping mission first and delaying everything by years? At what resolution does a map become good enough to commit to?

I came at this from an odd direction. I build a space sim, and I had to invent everything between 463 m and a few centimetres in a way that never contradicts the real measurements.
I wrote up how, if the engineering side interests anyone:
https://space.zerog.live/info/terrain-article-page.html

But I am more curious about the actual question. How much of a planet do you need to know before you land on it?

I have been thinking about radical life and health span extension for some time and published my first long form piece on it recently: 'Living longer will make you a billionaire'

It covers the financial implications of a VERY long life.

The compounding math is simple but it has fundamental implications for society.

Some questions that have come up in my salon:
- Do we have runaway inflation to accommodate the wealth?
- Do pension funds disappear as people have enough time to become their own pension funds?
- What happens to the fertility crisis: do people have fewer or more children and does the 'ageing population' problem finally go away or does it present in new forms?
- What happens to inheritence?

I mean, plenty of human drugs work in a lot of animals. What are the chances of any drugs working in aliens and which drugs would be likely to have the widest applicability? Stimulants maybe?