Let’s look at important things here –
Mars - Mars represents our will power, courage, ability to take actions, aggressive nature, anger, our fighting ability, brother, male friends, a boy friend for a girl, a soldier, an athlete and real estate etc.
Moola Nakshatra - It is a nakshatra of research, digging deep and knowing the hidden truth of things and people in life. For more information on Moola Nakshatra, please read this - https://www.astrosaxena.com/Moolnaksh .
Sagittarius - As Moola is part of Sagittarius sign, Sagittarius and things represented by Sagittarius are important here. Sagittarius is the 9th sign of Zodiac Belt, hence it represents many things related with the 9th house of horoscope like Religion, Knowledge, Wisdom, Higher Learnings, Gurus, Teachings from your Father etc. Besides it also represents Coaching, Universities, Professors and Preachers, Higher Wisdom, Written Law of the Land etc. Sagittarius has 2 and half nakshatra which are Mula, Purva-Ashadha and Uttara-Ashadha. Sagittarius' lord is Jupiter.
Ketu - As Ketu rules Moola, Ketu's position and dignity is important to know about the overall functioning of any planet in Moola.
Jupiter - As Jupiter rules Sagittarius, their position and dignity is important to know about the overall functioning of any planet in Moola/Sagittarius.
Houses Involved – Also, we can’t afford to forget the houses involved as a planet can be ruling different houses and sitting in different house for every person as per ascendant and planet’s position. To know overall affect, we have to consider the houses involved as those areas of life are being impacted.
Interpretation of Mars in Moola Nakshatra – Now, Mars's actions and energy is going towards the research oriented field. As Moola is part of Sagittarius which represents higher education and Moola itself represents research, Mars in Moola/Sagittarius can show someone who can be excellent in any research oriented subject. Mars will give him enough strength and commitment to keep on researching things unless and until he finishes the task. As Mars is in friendly sign, it is a good position for academics and research. Moola's obvious result of Occult and Mystical interests would be there with this position.
At the same time, Mars is fiery planet and Sagittarius is a fire sign. So, when Mars is in Moola/Sagittarius, it is like double fire energy in that particular house. Now, if we include that Moola is ruled by Ketu and Mars-Ketu combination is always explosive then it shows that this person can be fiery by nature and can easily get angry. As Ketu is headless, they can throw their anger at innocent people without thinking. So, in relationship matters, this position of Mars can be troublesome. As Mars represents Brothers, Boyfriend and Male Friends, there is a possibility of aggressive relation or almost no relation/complete separation from them. Overall, a planetary position which can give good knowledge but can be challenging in matters of relationship.
Role of Ketu – Ketu placement is important to guide Mars in right direction, being Moola's lord.
Role of Jupiter - Also, Jupiter placement is important to guide Mars in right direction, being Sagittarius lord.
Other Factors – And of course, we need to consider conjunction, aspects, house lordship, house position and dashas etc to know the exact results of Mars in Moola. So, we always need to take a holistic view of chart rather than just 1 planetary position.
Conclusion – So, this is how I see Mars in Moola can work in a chart.
Hope this helps. Please post any comment or query you may have.