Nearly 10,000 people gathered on Thursday as NASA's enormous new rocket started its maiden visit to a launchpad in preparation for a battery of tests that will allow it to blast off to the Moon this summer.

It departed the Vehicle Assembly Building at 5:47 pm Eastern Time (2147 GMT) and began an 11-hour voyage on a crawler-transporter to the hallowed Launch Complex 39B, four miles (6.5 kilometers) away.

With the Orion crew capsule attached to the top, the Space Launch System (SLS) Block 1 stands 322 feet (98 meters) tall – higher than the Statue of Liberty.

Despite this, it will deliver 8.8 million pounds of maximum thrust (39.1 Meganewtons), 15% more than the Saturn V, making it the world's most powerful rocket when it launches.

NASA administrator Bill Nelson called the rocket the world's most powerful, as he spoke to a crowd, adding, "We imagine, we build, we never stop pushing the envelope of what is possible." 

$4.1 billion of power

The rocket comes at a high cost: $4.1 billion per launch for the first four Artemis missions, according to NASA Inspector General Paul Martin, who testified before Congress last month.

After arriving at the launchpad, there are typically two weeks of inspections before the "wet dress rehearsal."

Artemis-1, an uncrewed lunar mission that will be the first combined flight for SLS and Orion, is set to launch in May, according to NASA.

SLS will first place Orion in low Earth orbit before performing a trans-lunar injection with its upper stage.

This maneuver is required to take Orion 280,000 miles beyond Earth and 40,000 miles beyond the Moon, which is the furthest any spaceship capable of transporting people has traveled.

Orion will release ten shoebox-sized satellites known as CubeSats during its three-week mission to collect data on the deep space environment.

Three mannequins recording radiation data and a plush Snoopy doll, long a NASA icon, will be among its "passengers".

It will journey around the far side of the Moon using thrust provided by the European Space Agency (ESA) thruster and finally make its way back to Earth, where its heat shield will be tested against the atmosphere.

SLS is referred to by NASA as a "super heavy lift exploration class vehicle." The only operating super-heavy rocket at the moment is SpaceX's Falcon Heavy, which is smaller.

Elon Musk's business is also working on its own deep-space rocket, the totally reusable Starship, which he says will be ready for orbital testing this year.

Direct comparisons are hampered by the fact that, whereas SLS is meant to travel directly to its targets, SpaceX envisions launching a Starship into orbit and then refueling it with another Starship to enhance range and cargo.

NASA has also contracted with Starship to build a lunar descent vehicle for Artemis.

Blue Origin's New Glenn, China's Long March 9, and Russia's Yenisei are among the other super-heavy rockets in development.