"In every SpaceX animation, we saw a fade into black right when people walked out of the rocket on Mars," Ellis said. "So what was clear [is] that there needed to be some other company building humanity's industrial base on Mars. Replicating the infrastructure for a million people that live on Mars is a massive undertaking, and I think a lot of people need to work on it."

Relativity seeks to do this by pushing forward 3D-printing technology. Ellis intends to disrupt the long-standing aerospace practice of using fixed tooling to manufacture rockets, which are then finished using a hands-on process of adding thousands of parts. Ultimately, Relatively hopes to use what it learns about printing rockets on Earth to additively manufacture habitats and other materials on the surface of Mars.

Even as Relativity Space seeks to augment the efforts by Musk and SpaceX to make humans a multiplanetary species, the company is also directly competing with its much more established rival. If successfully developed, the Terran R would challenge SpaceX's Falcon 9 rocket for both government and commercial launch contracts. //

The Terran R vehicle will have a first stage that lands on a drone ship at sea, and the second stage will retain its payload fairing after satellite separation. Then, this combined stack, the second stage and payload fairing, will make a propulsive landing from orbit.

"To my knowledge, we're only the second fully reusable vehicle other than Starship that's even been planned," Ellis said. //

The rocket's first stage will be printed from a custom aluminum alloy, and the upper stage will be built from a more exotic, heat-resistant material to withstand re-entry temperatures. For the rocket's first missions, Relativity will seek to bring back the first stage, incorporating full-vehicle reuse over time, Ellis said.

If all of this sounds ambitious, that's because it is, especially for a company that has yet to launch a rocket or even perform an integrated-stage test firing. However, Relativity's steady growth, to about 400 employees now, and total fundraising of $1.34 billion lend some credence to the idea that it may indeed be successful.