Why forecasting astronaut launches is more complicated

The SpaceX Crew Dragon escape system is designed to protect astronauts in the event something goes wrong during launch.

NASA and SpaceX made the call over the weekend to delay an astronaut launch on Halloween due to weather, but it wasn't the forecast around the Florida launch site that was concerning. It was what was happening miles away from Cape Canaveral in the North Atlantic. 

SpaceX's Crew Dragon capsule was set to launch Sunday morning with four astronauts, three NASA and one European, on the Crew-3 mission to the International Space Station. Liftoff has since been rescheduled again due to a minor medical issue with one of the astronauts. 

The spacecraft has a safety system known as the emergency abort or launch escape system, designed to detect any malfunction with the rocket. If something goes wrong, the spacecraft would separate from the Falcon 9 rocket sending it away for a water landing and far from any potential mishap during liftoff. 

Before launching any humans, SpaceX tested the Crew Dragon's launch escape system by intentionally blowing up one of its Falcon 9 rockets off the coast of Florida. The Crew Dragon has eight super Draco engines that move the spacecraft half a mile in under 8 seconds, pushing it away from an explosion at more than 437 mph, SpaceX engineer John Insprucker said during the January 2020 test. 

Over the weekend, weather officers with the 45th Weather Squadron were forecasting a 90 percent chance of liftoff. Still, the conditions along the spacecraft's ascent path would mean an abort could put the Crew Dragon in less than favorable wave heights.

"We had a 90 percent probability of 'go' here at the launch site, but it's not just the weather here that we're looking at. We're looking at the weather all along what we call the ascent corridor. So that's up the entire eastern seaboard as that rocket is going into space carrying the astronauts," 45th Weather Squadron launch weather officer Brian Cizek said. 

An area of low pressure departing from the east coast into the northeast U.S. was causing high winds and seas along the rocket's ascent corridor, ultimately causing NASA and SpaceX to push the launch. 

The 45th Weather Squadron, a group under Space Force's Space Launch Delta 45, is responsible for the Eastern Range, including the launch facilities and the Atlantic Ocean adjacent to the launchpads, about 15 million square miles of land and sea.

Weather is the primary reason for a launch scrub. However, according to 45th Weather Squadron launch weather officer Mark Burger, roughly two out of three attempts launch on time.

For a launch without people on board, the weather criteria typically end as the rocket accelerates away from Florida's coast. When it's a launch with astronauts at the top of the rocket, the weather continues to be significant along the ascent corridor of the rocket. The potential landing area for an abort runs from Florida up to the North Atlantic and to Ireland. 

This dramatically expands the area forecasters are looking at ahead of liftoff and when the astronauts return for landing.

"And so we're actually looking at the weather as well during that ascent corridor, in case of the unfortunate incident of there being an abort," Burger explained. "You need to make sure that the crew can safely abort in case of any sort of malfunction."

Those weather criteria along the flight oath include wind, thunderstorms and wave height. Weather forecasters must factor in the safety of the astronauts and the recovery teams who go to collect the capsule at sea. 

"Because obviously, if the waves are too high, then getting recovery vessels to that area could be an issue as well," he said. "So there's a number of different complicated criteria, and that planning actually begins in the case of a crewed mission out ten days from the projected time."

Launch delays because of weather along the ascent corridor will be commonplace as astronaut launches continue. In April, the Crew-2 launch also faced delays due to launch escape conditions.