I really like "Our Blue Ghost lunar lander now has a permanent home on the lunar surface..."
It's rare that usage of word "permanent" has this close to an accurate meaning. Complete development of the moon's surface aside, what are the factors what will destroy it? Solar and cosmic radiation? What timescale are we talking about here?
The're a surprisingly high flux of micrometeoroid impacts at the lunar surface. Most of these are too small to do much damage, but there will probably be measurable erosion in centuries and genuine damage within about 1 million years. The timeline for it to be destroyed/completely broken down is much longer.
For context, there's roughly a 50% chance of an astronaut being hit by a micrometeoroid large enough to kill them every 1.3 million years of time spent on the moon's surface. There's roughly a 50% chance of a square meter of the moon being hit by a micrometeoroid equavalent to 3 kg on TNT in a billion years.
Thank you for seeing through my sloppy writing, and identifying what I was getting at. I should have have said "aside from human intervention."
So, aside from the human intervention, and assuming that the materials can generally withstand radiation... let's say it's 6 sq meters, [0] I know this is not exactly how it works, but if LLMs[1] and my own lacking skills at mathematics are accurate, then ~70 million years? That sounds so much more "permanent" than anything on Earth.
Water in concert with temperature flux is really destructive causing a massive amount of erosion here on Earth.
With that said thermal cycles on the moon are very large, with a range up to 450F. That much thermal expansion and contraction over time is going to be hard on anything not shielded under some soil.
>Aluminum does not have a distinct fatigue or endurance limit, so its S-N graph curves down from the upper left to the right and continues to curve down lower and lower toward the lower right corner of the graph. This illustrates that it will eventually fail even from low stress applications, given enough of them.
Steel/titanium, if its fatigue tolerance is in the temperature range, would last much longer if not near indefinably until it came to impacts.
Overwhelmingly likely to be human interference, even without "complete development of the moon's surface".
Perhaps somebody thinks it would make a good museum piece back on Earth, or some bored spacefaring teen vandals destroy it for the lulz, or religious norms will change and those in power will blow it up to show their rejection of idols of a now forbidden age.
One person's rubbish is another's priceless artefact.
Landed craft on the moon often carry reflectors that help laser location of the Moon.
Spacecraft that have spent decades the Moon's surface are also going to give valuable clues about the behavior of their materials in these conditions, if / when someone collects and inspects them. Could save quite a bit of uncertainty for a larger project on the Moon.
Also, isn't basically everything you see on the moon some kind of debris? There are no apparent structures there created by complex, interesting processes, such as life, or by interesting geological processes. The spacecraft would be an aesthetical center of the area :)
