Well, when Tsumugi is moving around in the space, she creates a Higgs particle jet just like a Gardes. Now, Gardes clearly creates the jet from its engine, but how about Tsumugi? Does she...fart? Is that it? Does she fart Higgs particles to jet around?
The reason I asked this is that a human's fart contains methane which is combustible. And since Tsumugi is shown to produce a blue jet of Higgs particles from under her dress... Does a similar mechanism apply here?
Tsumugi is a human-gauna hybrid and has the same Placenta that the gauna use as an all-purpose organ. It is capable of shapeshifting into whatever form is needed at the time, as seen when the gauna begin to have heigus, or Higgs, particle cannons of their own.
Similar to the Benisuzume, Tsumugi has a portion of her body dedicated to keeping a heigus particle engine. Heigus particles appear to exist everywhere given how energy is passively collected. Sidonia and its gardes have heigus particle collectors that can be deployed like solar sails.
So Tsumugi is using the heigus particles she collected to propel herself.
In episode 6 of the second season, during the test of the new propulsion system by Samari's team, a member of the test team asked Tsumugi, who joined the test without prior notice, "How do you even generate thrust, anyway?" Tsumugi replied in embarassed tone, "I don't really know."
This suggest that Tsumugi produce the propulsion herself. Since the bright propulsion came from under her skirt-like thing, it means that whatever organ she use to accelerate is located there.
