Weather Is Key To Rocket Launches

NASA is gearing up for the launch of its massive Artemis moon rocket, with the weather playing a key role.

About half of all launch scrubs are due to weather, and the Artemis mission has already been impacted by weather several times.

The mission of the massive Space Launch System rocket built by Boeing is to send an unmanned Orion capsule into orbit around the moon, in preparation for taking humans back to the lunar surface within the next couple of years and, in the future, farther into deep space.

Here are some important points to know when it comes to Artemis, rocket launches in general, and the weather.

Launches rely heavily on the weather. The U.S. Space Force's 45th Weather Squadron, based at Patrick Air Force Base near the space center, is responsible for launch day forecasts. "Statistically, any given launch attempt has a 1 in 3 chance of scrubbing," Squadron Launch Weather Officer Melody Lovin said in a recent email. "Of all launch scrubs, half are due to weather at Cape Canaveral."

NASA's first Artemis launch attempt was scrubbed on Aug. 29 due to technical issues with the rocket. But weather also played a role. Fueling was delayed the night before due to lightning, which set back the countdown. And while the pre-launch forecast was favorable, storms rolled in right around the time the launch window opened, which would have caused delays.

The weather squadron issues one-page updates that include a weather summary and the odds of conditions violating specific weather constraints such as lightning, clouds, temperature, precipitation and wind shear. The latest forecast is here.

The forecast also takes into account weather at the booster recovery site, when applicable. SpaceX, for example, reuses its Falcon 9 rocket boosters. After launches, the boosters land either on a ship in the Atlantic Ocean or on land at Cape Canaveral Space Force Station. The SLS boosters won't be recovered and reused, so that's one less weather hurdle to clear. If a crew was on board, abort weather would also be more of a concern.

Lightning is always a concern. Lovin and her team worry about two types of lightning - natural and triggered. When there’s electricity in the atmosphere, a rocket and its plume can spark "triggered lightning" by acting as conductors. The electrical field required is much lower than for natural lightning, and it's happened at least twice before – during the 1969 launch of the Apollo 12 moon mission and again during an unmanned launch in 1987.

The Artemis launch pad has been struck by lightning several times. Strikes happened when the rocket was on the launch pad for testing earlier this year, and it was hit on Saturday, Aug. 27, during a prelaunch countdown. That strike was caught on video.

NASA's last big history-making launch was delayed due to stormy weather. SpaceX's Crew Dragon Demo 2, which launched humans from U.S. soil for the first time in nearly nine years, was set to lift off on the afternoon of May 27, 2020. But storms moved in and there was even a rare tornado warning issued for the area. The launch was called off with 17 minutes left in the countdown. The rocket took off three days later.

It's not just NASA that's worried about the weather. Up to 500,000 visitors are expected to flood Florida's Space Coast to watch the launch. They'll need to keep an eye on the local forecast and be especially careful of lightning and heat. Florida's hot, soupy August weather could push the heat index over 100 degrees during the launch window.

Much of the rest of Florida has high hopes for clear skies, too. The 322-foot-tall, 5.75-million pound SLS will be the most powerful rocket ever launched into space, producing 8.8 million pounds of thrust. All that power and size means that if skies are clear the rocket will be visible from farther parts of the state than a typical SpaceX Falcon 9 launch, much like the Space Shuttle launches were from the 1980s until the program was curtailed in 2011.

If you can't see it in person, NASA will live stream the event here.

Want to know more? Here's some of our other Artemis-related coverage:

NASA Is Sending Two Female Mannequins To The Moon

NASA Unveils New Spacesuits For Artemis Mission

NASA Opens 50-Year-Old Moon Sample

Parts Of Moon Are Right Temp For Humans

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.