On Friday, SpaceX CEO Elon Musk will be giving a “major” update on his plans to colonize Mars during a presentation at the International Astronautical Congress in Adelaide, Australia. His talk is meant to add to the one he gave at last year’s IAC conference in Mexico, when he revealed the full architecture of his plans to send thousands of peoples to the Martian surface. This time around, it seems his speech may revolve around making the concept more feasible — mainly by scaling things down.

Musk has only dropped a few hints about what he’ll talk about this week, but we can probably expect the announcement of a smaller launch vehicle, as well as ideas for how to pay for the high costs of developing such a rocket. He’s also said there will be a few surprises regarding how the vehicle will be used.

Headed to Adelaide soon to describe new BFR planetary colonizer design in detail @IAC2017. This should be worth seeing. Design feels right. — Elon Musk (@elonmusk) September 27, 2017

Here’s a few points Musk will likely talk about this week, as well as other things we’ll keep our eyes peeled for.

A smaller vehicle

Central to Musk’s Mars colonization plans is a massive rocket and spaceship combo dubbed the Interplanetary Transport System that will be used to ferry people to and from the Martian surface. But Musk has suggested a few times this last year that he will present a new, smaller version of the vehicle in the pursuit of practicality.

The current vision for the ITS, unveiled last year, is a rocket that can lift a ship carrying up to 100 colonists. The majority of the rocket booster is supposed to land back on Earth after takeoff — just as the company’s Falcon 9 rockets land post-launch. Meanwhile, the ship portion is meant to remain in orbit, waiting for another launch that will bring the fuel it needs to travel onward to Mars.

The design for this system called for a truly massive vehicle. The rocket booster and spaceship combined would tower over 400 feet high, making it taller than NASA’s Saturn V rocket that took astronauts to the Moon. Plus, the ITS would sport a nearly 40-foot diameter, with a whopping 42 engines at its base. Built this way, the ITS would be the largest rocket ever created. Its immense size is partially why Musk referred to it as the BFR — or Big Fucking Rocket — for years before he unveiled the design last year. (And the nickname hasn’t quite gone away.)

A 9m diameter vehicle fits in our existing factories ... — Elon Musk (@elonmusk) July 22, 2017

However, Musk has said he’ll call for a scaled-down version of the vehicle, perhaps one that is only 30 feet wide. That would mean the new vehicle will probably be shorter, too, with a fraction of the engines compared to the original design.

That could make the ITS a more versatile vehicle. “When you do scale something down, it tends to have more uses,” Bobby Braun, an aerospace engineer and dean of the College of Engineering at the University of Colorado, Boulder, tells The Verge. For instance, the Saturn V was designed for just one thing: putting people on the Moon. Whereas smaller launch vehicles, such as SpaceX’s Falcon 9 or the United Launch Alliance’s Atlas V, are used for a wide variety of missions, like launching satellites and lofting cargo to the International Space Station. A smaller ITS may have more utility than just sending people to Mars; Musk even posted on Instagram that “certain aspects of the new design and its applications will be unexpected.”

To be clear: a 30-foot-wide vehicle is still going to be a huge rocket. “It’s still bigger than anything that exists today,” Braun says. “So we’re scaling down from something that’s ginormous to something that’s just big.”

Affordability

A smaller, more versatile vehicle may help with another critical issue surrounding Musk’s Mars ambitions: affordability. One of the main criticisms of Musk’s idea last year was just how unrealistic it seemed in terms of development costs and timeline. SpaceX is known for making low-cost vehicles compared to the rest of the industry, but a giant rocket the size of the ITS would likely cost billions to develop. Plus, Musk said SpaceX could start sending the first colonists to Mars as early as 2024, though he said that the company is only investing 5 percent of its resources into the project at the moment.

Mars V2 plan coming soon, which I think addresses the most fundamental flaw in V1: how to pay for development & operation of giant rockets https://t.co/yaITdVdpEc — Elon Musk (@elonmusk) June 16, 2017

Scaling down the ITS could certainly help with costs, since developing a smaller rocket may turn out to be slightly cheaper in the long run. And if it has more uses, as Braun suggests, then that could help with the economics. An ITS that can do more than just take people to Mars will have a much better business case, and likely more companies wanting to use it. “A smaller rocket probably flies more, and there are probably more customers for it,” says Braun. That could potentially pay for the costs of the rocket’s development.

Musk seems to be thinking along the same lines: “The key thing that I figured out is: how do you pay for it?” he said at the International Space Station Research and Development conference in Washington, DC in July. “If we downsize the Mars vehicle, make it capable of doing Earth-orbit activity as well as Mars activity, maybe we can pay for it by using it for Earth-orbit activity.”

Perhaps a lunar detour?

Another way Musk could pay for his rocket is by asking the government for money, which is why we may hear about more than just Mars on Friday.

For years, Musk has been Mars’ biggest fanboy, arguing that humanity should head straight to the Red Planet without setting up a colony on the Moon first. But in recent months, the CEO has changed his tune slightly. In February, SpaceX announced that it would be sending two tourists on a trip around the Moon sometime in 2018. Then in July, Musk proclaimed at the ISS R&D conference that he thought establishing a human presence on the Moon was part of the dream of the Apollo missions. "To really get the public real fired up, I think we've got to have a base on the Moon,” he said at the conference.

Musk’s recent admiration for the Moon may have to do with shifting political winds. During the Obama administration, NASA was singularly focused on its “Journey to Mars,” the space agency’s goal of sending humans to the Martian surface. But after last year’s election, there have been major hints that the Trump administration will shift its focus to the Moon again. NASA is already planning to build a Deep Space Gateway in the space around the Moon. And in a speech at NASA’s Kennedy Space Center in Florida, Vice President Mike Pence proclaimed that “our nation will return to the Moon,” though he didn’t specify how. Plus, the executive director of the newly formed Space Council, Scott Pace, has said openly that NASA’s shift away from the Moon during the Obama administration was a big mistake.

“there are hints that NASA is going to refocus to go back to the Moon in the near future and not Mars.”

This is all just speculation at this point, but it’s possible that on Friday Musk may add how the ITS could be used for lunar missions in an attempt to court NASA into some funding. During his speech last year, Musk hinted heavily that he would need government money in order to develop the ITS. But that was when NASA was solely looking to Mars. If the Trump administration directs NASA to return to the Moon, Musk may have a better time getting funding by mentioning the Moon, too.

“It was last year when he sort of dropped the hint that maybe he might need government funding, which most of us assumed all along,” Brian Weeden, a space expert and director of programming for the Secure World Foundation, tells The Verge. “The challenge is there are hints that NASA is going to refocus to go back to the Moon in the near future and not Mars. And so I’m not sure whether Elon and SpaceX are going to be well positioned for that.”

Plus, it’s not just NASA that wants to go back to the Moon. Europe, Russia, and China are all interested in lunar missions and habitats, as well as private companies such as Lockheed Martin, the United Launch Alliance, and more.

Unanswered questions

There are still a lot of unknowns regarding Musk’s Mars plans, such as how people are going to survive on the Red Planet. He gave no indication of what their habitats would look like, nor what life-support systems would be used. “I think the core question of what they’re going to do when they get there and why they’re going to Mars is a key issue,” says Weeden.

“why they’re going to Mars is a key issue.”

It’s possible we may not get more updates about that. During his talk last year, Musk noted he’s more focused on getting to people to Mars and less on the technology needed to keep them alive there. “The goal of SpaceX is really to build the transport system. It's like building the Union-Pacific Railroad," said Musk last year. "And once that transport system is built, then there's a tremendous opportunity for anyone who wants to go to Mars and create something new, or build the foundations of a new planet."

Of course, we won’t know anything for sure until Friday. Musk is giving his presentation at 2PM Australian Central Standard Time, which is 12:30AM ET on Friday (and 9:30PM PT on Thursday). Conference officials have said there will be a live stream, so for those in America looking to stay up late, it should be an interesting show.