No, the ITN isn't the only way to travel, and it's not what MOM is using. It's just doing a Hohmann transfer, which is just about the most basic orbital maneuve

No, the ITN isn't the only way to travel, and it's not what MOM is using. It's just doing a Hohmann transfer, which is just about the most basic orbital maneuver possible. The ITN is the clever, sneaky way to travel between planets with a shoestring fuel budget by bouncing around chaotically. It can be better, but it does tend to take a whole lot longer. Note that even a standard Hohmann doesn't need to spend any fuel until arrival (aside from minor course corrections). But with the ITN, it's potentially cheaper to achieve certain chaotic trajectories than it is to change the orbit enough for a Hohmann.