Since debuting an unprecedented vision for getting colonizers to Mars, SpaceX CEO Elon Musk hasn’t revealed many more of the finer details behind what it’s going to take to ship thousands of people sprawled across dozens of ships at once, ferry them to Mars, and then come back and do the whole thing all over again, and again, and again — until we have a million people on Mars inhabiting the first-ever extraterrestrial city.

That’s the idea behind the Interplanetary Transport System, or ITS. On Sunday, a Twitter user asked Musk when we might finally hear about updated details for the ITS architecture and design.

Well, sort of. The question was actually posed as: “Eta on the ITS/BFR/MCT architecture changes?” And as you can see, it lumps in three different acronyms which all relate to SpaceX’s plans for Mars travel.

Musk’s response to the Twitter user was pretty succinct: “Almost there. Probably in a few months.” But in order to really understand that answer, it’s worth unpacking exactly what ITS, BFR, and MCT all mean.

First, we’ll start with MCT, which stand from Mars Colonial Transporter. This was the first label for SpaceX’s Mars transport architecture and was replaced with ITS last fall, when Musk gave his talk at the International Aeronautical Congress in Guadalajara, Mexico. SpaceX barely divulged much information about what exactly the MCT was, so for all intents and purposes, the MCT is not a thing anyone should worry about understanding anymore.

The ITS, meanwhile, is the transportation system Musk and his team have come up with for taking human beings to Mars for a relatively inexpensive $200,000 per person. You can read more about it here, but the basic idea is to make nearly all necessary hardware reusable again and again, and develop a way to manufacture methane-based fuel on Mars itself.

A key part of that will be the BFR, which is short for — and I kid you not — Big Fucking Rocket. This is basically supposed to be the most powerful rocket in the world — exponentially bigger than the Falcon 9, and even more powerful than the vaunted Falcon Heavy which will debut later this year. Musk has said before the thrust of the BFR should be equivalent to something like 120 Boeing 747s firing their engines all at once.

BFR Wait But Why
A totally excellent illustration made by Wait But Why of how big the BFR will be.

But again, the exact details for the BFR, like the ITS, are slim. We have some cool animations, sure, but they don’t tell us anything about how these pieces of technology will work from a technical perspective.

“A few months” is not much to go on, but the end of September marks the one year anniversary of Musk’s IAC talk, which happens to be — you guessed it — around the same time as this year’s IAC, which takes place September 25-29 in Adelaide, Australia. It’s still not clear whether Musk will be giving a talk or even attending this one as well, but it’s almost a certainty SpaceX will be participating in some way, and that’s probably when we’re going to get more information on what the ITS and BFR will entail.

Let’s just hope the company at least sticks to the name BFR.

Photos via Wait but Why, SpaceX, Getty Images / Justin Sullivan