The Anarcho-Technological Union of Shackleton is a anarchist polity residing in and around Shackleton crater on the Moon's south pole.
Their flag is composed of a stereotypical 'anarchist' flag with the hoist-bisection in 'technological and lunar' grey, a black roundel hoisting a 'A' whose legs end in circuit-board (and thus technological) symbology surrounded by a grey circle, which represents Shackleton-on-the-pole, and indeed, many have noted that the whole flag looks like a stylized view of their settlement, with the near side in grey and the far side in black.
All but an engorged scientific and cultural experiment, the Anarchism there is all but 'classical' communist/socialist/anarchist. Where the details fall is left to observer and participant alike, but it's still very democratic, very 'free', and communal, though tempered by the harsh realities of living in space. Social control and development does exist along some secret manifesto, but the purges haven't started, not yet at least.
Whether or not in the end the anarchist experiment will 'succeed' without implosion is left to heavy debate. It's only been fifty odd years, after all. Some decry external influence, others seek to spread their way, and others still wish to maintain a community of scientists and technology, free from the pressing demands of profit and capitalism.
Here's another polity from my hard-mundane scifi setting. Gods, I hope metallic hydrogen was actually reproduced in a lab....
Mangalan Shambhala, or, in English, the 'Martian Place of Peace', is a theocratic Buddhist state formed around Newton Crater (now hosting a large lake, companion lakes, and gentle grassland below the rim) on, well, Mars.
The flag of Mangalan Shambhala is composed of a orange fesswise pall fimbriated white (a horizontal Y with white borders), representing the Three Jewels of Buddhism.
On top of the pall is a white roundel hoisting four rounded orange semi-circles, which represent the Four Noble Truths, and centered in the circle is a stylized Dharmachakra representing the Noble Eightfold Path. The spokes of the Dharmachakra are a fluffy star, representing spatial and expansive matters/aspirations.
As per their national reckoning of Buddhism, it is ruled by the Maitreya, or the future perfect Buddha; at least, this is the title for their leader, who functions as an absolute theocrat, who is focused on fulfilling the prophetic Kalacakra tantra and to defeat the myriad of 'dark forces' tormenting humanity, with a schedule slated for 2424 AD/467 SE.
To fulfill this goal, extensive mining operations, arms production, militarization, and propaganda is churned out of Mangalan Shambhala at astonishing and inhumane rates. It is rated as a rogue state with abysmal human rights and democracy thereof by the rest of the inhabited solar system, but unlike other such polities (which normally consists of rich fundamentalists, their inner circle, their followers and a cheap off-the-market inflatable habitat or two floating in space or on some rock) their expansive holdings and technology gives them a potentially painful bite behind their bark.
Colors: 3: Dark Grey, orange, and white, which symbolize the darkness of existence, concurrent affairs, and space; Buddhism; purity, and holiness, respectively.
Here it is in flagwaver.
"The current flag of Puerto Rico, designed in New York, based on the Cuban flag, itself designed in New York and based upon on the flag of the United States of America and a desire to become a state of the United States of America, stands to be decolonized - a general interest I myself have dabbled in, as a Puerto Rican.
The colors and symbology of the flag are as follows: the Spanish Red for the blood shed by the island in its course for independence against Spain and the United States of America in an ascending manner and symbolic of number and years of the struggle undertaken to do so; the White for the hopeful future with the triangle representing the three pillars of liberty, justice, and democracy; the five point Gold star for the island itself and its wealth, material or human, pointed outwards for a hopeful advancement; and the Spanish Blue triangle standing for the encompassing sea which surrounds and provides for Puerto Rico and the thee cornerstone industries of shipping, fishing, and medicine."
Produced in flagmaker 2.0.
The sickle stands for the tools, manpower, extraction, and capability of Ceres, in the form of hydrogen and oxygen from itself and as a base to exploit the asteroid belt. The bundles of grain stand for the riches and wealth provided by Ceres, or stand to be, and are composed of five stalks each to mark Ceres' 'fifth' place in the solar system. The dark field represents the realm of outer space.
While Ceres does not hoist any real permanent population nor representation, numerous bodies have a flag in spite of legal status, and this flag follows that trend.