why is mars' planet so unstudied?
It's largely unstudied because of the dominant species of the planet
Mars's species is very reserved and distrusting of outsiders and offworlders. They firmly believe that exposure to all the other species and planets would mean the inevitable and unavoidable death of their culture, heritage, and beliefs. So they typically chase away any outsiders and hold a lot of their knowledge and history close to their chest.
Its pretty common for people to be completely exiled for harboring any offworld objects, tech, or even offworld creatures. The only thing that was readily given over by them is their medical knowledge and study on their anatomy that way should any exiled members of their species need medical help they can recieve it. (They want them to live in shame, not die of disease or injury)
Even know, despite being exiled, Mars is still very resilient to sharing a lot of information about her home and her people. The only ones she really trusts with this information are Ango, Zai, and Gidget