Chance of weather scrub on Crew Dragon astronaut launch day ‘very high,’ SpaceX officials say
NASA needs clear skies and calm seas from Cape Canaveral to Ireland
CAPE CANAVERAL, Fla. – For the first time since 2011, NASA is worried about smooth seas.
Space Shuttle launch criteria called for clear skies, low winds and calm seas in case astronauts on board needed to make an emergency landing.
Trans-Atlantic Abort, or TAL, sites in Europe had to have good weather, giving astronauts an option to bring down the Shuttle overseas.
And the Atlantic Ocean under the Space Shuttle’s flight path to orbit needed to be mostly calm. If all else failed, astronauts had an option to put the Shuttle in a glide, climb out on a pole and parachute into the water.
In recent years, for SpaceX’s cargo missions to the International Space Station, only weather in the sky was of concern.
However, on May 27, with two astronauts on board the Crew Dragon capsule, sea state will be critical again for the first time in 9 years.
Crew Dragon can only touch down in water, at the end of the mission but also anytime in case of a mission abort.
Dragon’s flight path to orbit brings it up the eastern seaboard, over the Atlantic Ocean and high above Ireland.
NASA's Crew Dragon weather launch criteria calls for a no-go "if downrange weather indicates violation of limits at splashdown in case of Dragon launch escape" and "if downrange weather shows high probability of violating limits at splashdown in case of Dragon launch escape."
"Downrange" - from Cape Canaveral to Ireland - is thousands of miles of ocean.
NASA said downrange weather is monitored "at more than 50 locations along the ascent track along the North American eastern seaboard and across the North Atlantic."
Because of the large area, factoring in weather in the skies - no lightning, no thick clouds, no high winds - SpaceX Director of Crew Mission Management Benji Reed said the chances of good weather on launch day are poor.
“I would expect there to be a very high chance of scrub due to the weather,” Reed said. “And given the time of year, it wouldn’t surprise me as well.”
Former NASA shuttle test director and contingency planner Stephen Payne said NASA and SpaceX will evaluate the weather each day on a case-by-case basis.
"If the entire path has heavy winds and high seas, then that's an easy decision," Payne said. "If the path is clear but there's a patch that's not so good, perhaps you can adjust your abort range to cut it before or sometime after to avoid that piece, so there's no real cut or dried answer. There's a lot of things that have to go into the equation."
NASA echoes that in its launch weather criteria: "Probability of violation is calculated for each location including limit conditions for wind, waves, lightning, and precipitation."
News 6 Chief Meteorologist Tom Sorrells took a snapshot of the sea heights about a week before launch, as an example.
“We go up the coast to the Carolinas, things build a bit,” Sorrells said. “Wave heights off Boston are up to two feet, I think we’re a go. But you get up to Canada though, Halifax and St. John, there’s a big pocket right over Nova Scotia that has a 14 feet wave recording on a buoy out there, that might be enough to shut it all down.”
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Sorrells estimates only a 30% chance of favorable weather on any given launch day for the astronauts.
Payne said no launch day will have perfect weather.
“There’s been a lot of discussion as to how much is sea state is too much sea state,” Payne said. “Because it’s such a large portion from here all the way to Ireland, that’s where we’re flying, somewhere in there there’s bound to be a patch of bad sea. So how much is too much? What’s reasonable to expect with crews that have to go jump into the water and try and open the hatch, you balance that with what’s the crew going through and heavy seas inside the capsule if for some reason they’re not in good shape.”
Payne said the decision to launch is ultimately a calculated risk.
“If you do an all-or-nothing calculation then you’ll never launch, and that’s not the point,” Payne said. “The point is to find where is it reasonably safe to launch.”
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