NASA is rolling its Artemis spacecraft and rocket to the launch pad for a final round of critical tests before blasting off for the moon, and you can watch the rollout happen live Thursday (March 17) at 5 p.m. EDT.
Tune in here on Live Science, or on NASA TV, the NASA app and NASA's website, to see the Orion spacecraft and the Space Launch System (SLS) rocket — the most powerful that NASA has ever built — as they depart the Vehicle Assembly Building at Kennedy Space Center in Cape Canaveral, Florida, and travel 4 miles (6.4 kilometers) to Launch Pad 39B.
Orion and SLS will be perched atop the massive Crawler-Transporter 2 (CT-2), one of two flat and ponderous vehicles that were built in the 1960s for Apollo moon mission launches. The crawler measures 131 feet (40 meters) long and 114 feet (35 m) wide, and it weighs about 6.7 million pounds (3 million kilograms), according to NASA. With the additional weight of Orion and the SLS, the crawler will weigh in at 21.5 million pounds (9.8 million kg).
Crawlers and their loads are so heavy that NASA engineers had to replace the asphalt on roads leading to Kennedy launch pads, because asphalt wasn't strong enough to support the vehicles' weight. Instead, engineers used layers of small, round river rocks that are made mostly of quartz; many small rocks distribute the force from heavy loads and can be easily replaced after they're crushed into gravel, NASA says. Today, the crawlerways are covered with about 70,000 tons (64,000 metric tons) of rocks from Jemison, Alabama.
CT-2 has a top speed of 1 mph (1.6 km/h) when it's bearing a heavy load. But during the rollout, the crawler will be moving more slowly than its maximum speed. There will likely be a few stops along the way, and cruising speed for most of the trip will be a leisurely 0.8 mph (1.3 km/h), Charlie Blackwell-Thompson, launch director for NASA's Exploration Ground Systems Program at Kennedy, said during a March 14 press briefing.
At that pace — about one-third of the average walking speed for a person — it should take approximately 11 hours for the stacked rocket and spacecraft to roll into position at the launch pad, Blackwell-Thompson said. So even if you miss the first moments when the rocket begins to roll, you'll still have plenty of time to watch its progress. After the crawler reaches the launch pad, engineers will then spend the next two weeks preparing the rocket for what is known as a wet dress rehearsal: filling the tanks with liquid propellant, performing countdown simulations and testing the rocket's responses to different launch scenarios.
"With this rollout of a great launch vehicle and spacecraft, it's going to kick off a new era of human space flight exploration," Howard Hu, deputy program manager of NASA's Orion Program, said at the March 14 briefing.
Check back here at Live Science for Artemis mission updates, including the official launch date for Artemis I, which NASA is expected to announce after the successful completion of the wet dress rehearsal. The anticipated date will be "no earlier than May 2022," according to NASA's launch schedule.
Originally published on Live Science.