Elon Musk shows off fully stacked SpaceX Starship and Super Heavy Rocket.

Highlights:

• Elon Musk’s SpaceX stacked a Starship prototype rocket on top of a Super Heavy rocket booster for the first time Friday morning.

• Elon Musk, asked by CNBC what he thought of witnessing the milestone at the company’s facility in Texas, responded simply that it was a “dream come true.”

• The SpaceX CEO also answered further questions about what’s next in preparing Starship for its first launch to orbit.

With three words, "Starship fully stacked," SpaceX founder Elon Musk is seeing his vision of the future become reality. On Friday, Musk shared photos of a prototype Starship spacecraft and Super Heavy rocket together on a launchpad with the business end down and the pointy end up.

Elon Musk’s SpaceX stacked a Starship prototype rocket on top of a Super Heavy rocket booster for the first time Friday morning, giving a look at the scale of the combined nearly 400-foot-tall vehicle.

SpaceX is developing Starship to launch cargo and people on missions to the moon and Mars. Starship prototypes stand at about 160 feet tall, or around the size of a 16-story building, and are built of stainless steel — representing the early version of the rocket that Musk unveiled in 2019.

The rocket lifts off on top of a Super Heavy booster, which makes up the bottom half of the rocket and stands about 230 feet tall. Together, Starship and Super Heavy are nearly 400 feet tall when stacked for launch.

Elon Musk's photo collection shows the Starship spacecraft being lifted to the top of the Super Heavy rocket and put into place.

SpaceX has conducted multiple short test flights of Starship prototypes over the past year, but reaching orbit represents the next step in testing the rocket. The company in May revealed its plan for the first orbital flight, which would launch from the company’s facility in Texas and aim to splash down off the coast of Hawaii.

While SpaceX’s fleet of Falcon 9 and Falcon Heavy rockets are partially reusable, Musk’s goal is to make Starship fully reusable — a rocket that is more akin to a commercial airplane, with short turnaround times between flights such that the only major cost is fuel.

One important piece of making Starship fully reusable is improving its durability to survive the intense process of reentering the Earth’s atmosphere. Small hexagonal heat shield tiles are SpaceX’s answer to that problem, with the previously shiny Starship 20 rocket now covered in thousands of the tiles.

Elon Musk noted that work on the tiles is about “98% done” for Starship 20, as “the remaining tiles are unique shapes requiring machining.”

NASA has been paying close attention to Starship’s development, especially as the U.S. space agency earlier this year awarded SpaceX a controversial $2.9 billion contract to deliver astronauts to the surface of the moon using the rockets.

A launch date for the test flight has not been set yet, and will depend on many factors, including finishing up the work on Starship and Super Heavy and getting approval from the Federal Aviation Administration. Sending Starship to orbit will be a big step toward Musk's even bigger dreams: carrying humans to the moon and Mars.