A constitution must rigidly describe a flexible system.
The constitution we eventually create will be the foundation of Asgardia for generations. As a foundation, it will have little to do with the actual day to day running of Asgardia. Instead, it will describe the governmental system that controls Asgardia, as well as a number of foundational rules that all public institutions and servants must follow. It will not say how much we will be taxed or what actions will be illegal. It will describe the rules that an Asgardian government must follow when determining these things. Because of this, it must utterly rigid.
When a government is in any way capable of increasing it's own power (or manipulating it's populace into doing so) it will inevitably do so. Then it will continue to do so in a downward, authoritarian spiral. I don't need to remind anyone how power corrupts over time. A constitution attempts to prevent this by setting a government's abilities in stone. When a society or it's government begin ignoring, neglecting, reinterpreting, or otherwise corrupting their constitution then the great leviathan of social organization ceases to be regulated by law. From then on it regulates itself or, in other words, is free to do as it wills. Inevitably it will devour us. The public servants will become the masters and the citizens slaves. History has shown it happening time and time again. This is why our constitution cannot waver.
However, any successful society must be flexible. No set of traditions will solve every circumstance. This is why a constitution describes a flexible government. A legislative body must be able to exercise creative thought and innovative problem solving. It cannot do this if it is rigidly bound. So, it must have (virtually) complete freedom within its jurisdiction, but regarding actions that conflict with the constitution, there can be no exceptions.
Regarding amendments, we obviously must allow for them, but we must not plan or welcome them. An amendment will only happen in one of 4 circumstances:
Fixing a mistake from the constitutions drafting. --- In this scenario, we have failed to write our constitution with enough care. It was rushed and is now hopefully being fixed. This option means we failed.
Adding new consideration for technology or social concerns that have never occurred before. ---This should be incredibly rare. Only inventions on par with the internet itself should be considered, and even then the change should be limited. The majority of change should simply be in new legislation created by the already flexible government.
Changing fundamental principles in the constitution because it no longer represents the views of Asgardia as a whole. --- At this point, while some kind of change should occur, such drastic circumstances arguably call for a completely new constitution. Regardless, this scenario shouldn't concern us. We must plan for our nation, not another.
As a mistake. --- It is possible that the constitution will be changed in an improper manner. This occurred in the USA with it's prohibition of Alcohol.
Given these 4 options. Only 1 and 2 will be positive for us. The first means that we should have done more during drafting, the second will be incredibly rare. Given this, we should not plan on the constitution changing often. The amendment process should be long and difficult.
Even with such an unknowable and volatile future as Asgardia's, it's foundation must be firm. If asgardia were a person the constitution would be it's skeleton. The government it's muscles, pushing off of and limited by the constitution.