For the last year or so, Stratolaunch has conducted a number of ground-based tests on the world's largest aircraft, both inside its gargantuan hangar and on a runway in Mojave, California. If all goes well, the company plans for the aircraft with a 117-meter wingspan to make its maiden flight by the end of this year.

But the aircraft is only a means to an end—sustainably launching rockets into space. Although Stratolaunch appears to have built a fine airplane, questions have lingered for years regarding exactly which rockets will be flown to a cruising altitude to then be released by the airplane. And when you've built an aircraft the likes of which has never been seen before, such curiosity is understandable.

On Monday, the company finally provided some additional clarity. Previously, Stratolaunch announced an agreement to launch small Pegasus rockets from the aircraft, but these boosters can only deliver up to 370kg into low-Earth orbit. (And they are so small, their use could not possibly justify the scale of the Stratolaunch plane, with a wingspan 20 meters greater than even the Spruce Goose).

Fortunately, the new rockets announced this week will have significantly more capacity, and they appear to be right-sized for this very large mobile launch platform:

Medium Launch Vehicle : A new medium-class air-launch vehicle optimized for short satellite integration timelines, affordable launch, and flexible launch profiles (3.4 ton capacity to LEO).

: A new medium-class air-launch vehicle optimized for short satellite integration timelines, affordable launch, and flexible launch profiles (3.4 ton capacity to LEO). Medium Launch Vehicle – Heavy : A three-core MLV variant with capability to deploy heavier payloads to orbit (6 tons to LEO).

: A three-core MLV variant with capability to deploy heavier payloads to orbit (6 tons to LEO). Medium Launch Vehicle – Reusable: A fully reusable space plane that enables advanced in-orbit capabilities and cargo return; Initial designs optimized for cargo launch, with a follow-on variant capable of transporting crew.

According to Stratolaunch, the medium launch vehicle is under development, with a maiden launch targeted for 2022. The heavier version of this rocket is undergoing "early development," and the company is performing a "design study" of the space plane. Earlier, Stratolaunch dubbed this space plane concept "Black Ice."

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Dylan Schwartz

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

Stratolaunch Systems Corp.

“We are excited to share for the first time some details about the development of our own, proprietary Stratolaunch launch vehicles, with which we will offer a flexible launch capability unlike any other,” said Jean Floyd, chief executive officer at Stratolaunch, in a news release. “Whatever the payload, whatever the orbit, getting your satellite into space will soon be as easy as booking an airline flight.”

Stratolaunch released no additional details about these rockets, such as the engines they will use. Even so, the moment feels significant, as Stratolaunch has long been searching for appropriate rockets to be launched from its aircraft. An earlier deal with SpaceX fell through, as well as a deal with Orbital ATK to develop a custom rocket for the aircraft. Now, the company has decided to go in-house and just build its own rockets.