'Star Trek: Discovery' Just Answered One of Its Biggest Continuity Questions

Tonight's episode of Star Trek: Discovery, "An Obol for Charon," finally answers a question that Star Trek fans have been asking since the series debuted.

SPOILERS for Star Trek: Discovery Season 2, Episode 4, "An Obol for Charon" follow.

If you're not quite up to date on Star Trek: Discovery, it follows the crew of the USS Discovery, a Starfleet science vessel with some of the most advanced technology that the United Federation of Planets has to offer.

The most significant technology on the ship is its unique mode of travel. While Discovery has the same standard warp drive you see in all other starships in the Star Trek universe, it also has an experimental spore drive developed by Paul Stamets. The spore drive is an organic propulsion system that uses mycelium spores harvested from mushrooms to travel through the subspace domain known as the mycelial network. The effect is near instantaneous travel from one point in the universe to another, possibly in rapid succession so long as the sentient being acting as a navigator can withstand the stress.

But Star Trek: Discovery is a prequel. And so, many fans were left wondering why all of the Starfleet vessels in all of the other Star Trek series still ran on warp drives when the spore drive was invented a decade before Star Trek: The Original Series begins.

"An Obol for Charon" provides the answer. Ensign Sylvia Tilly was infected by a fungal parasite. At first, it was believed the parasite was from the Mirror Universe, but "An Obol for Charon" reveals that it is actually a sentient lifeform native to the mycelial network.

Stamets and Jet Reno install a cortical node in Tilly that allows the parasite to speak through it. It tells Stamets that the species it belongs to lived harmoniously within the mycelial network, but that the jumps that Discovery has been making through the network have caused irreparable damage to the species' ecosystem. Stamets pledges to do whatever he can to help fix the damage that he's done.

While we don't know if or how Stamets can make up for the damage the spore drive has done, it is easy to see now why future Starfleet vessels don't use spore drives. The Federation and Starfleet are committed to preserving life whenever possible. To continue using the mycelial network when they now know sentient lifeforms are paying a price for it would go against everything Starfleet stands for.

What do you think of this new development regarding the spore drive? Let us know in the comments!

New Star Trek: Discovery episodes become available to stream Thursdays at 8:30 p.m. ET on CBS All Access.