4 ms·

*Pending weather

bonestamp2 6y ago
On this note, does anybody know what the weather thresholds are that would cancel the launch? I mean, the current forecast suggests it will almost definitely be raining at 433pm Eastern, and wind will be around 10 mph. Is some amount of rain tolerable? How much wind is acceptable?
- danbr 6y ago
  Here’s some information on the Space Shuttle Weather Launch Commit Criteria. There are probably some added bits for the water recovery incase of an abort with Crew Dragon. https://www.nasa.gov/centers/kennedy/pdf/531435main_weather-rules-march2011.pdf https://www.nasa.gov/centers/kennedy/pdf/531435main_weather-... Edit: and for the falcon 9 (non crew) https://www.nasa.gov/pdf/649911main_051612_falcon9_weather_criteria.pdf https://www.nasa.gov/pdf/649911main_051612_falcon9_weather_c...
bryanlarsen 6y ago
Nominally a 60% chance of a go for launch weather, but according to Ken the Bin on Ars Technica, the weather in the abort corridor is poor so he expects a postponement.
- lovelettr 6y ago
  I live on Merritt Island. Our power has been out since 6:30 this morning due to intense storms in the area. That having been said, it is currently sunny and calm. Given what the weather has been like since Sunday I could see it being postponed. I hope the weather holds and gives a window.
- gpm 6y ago
  Typically that percent chance doesn't actually consider all the launch criteria as crazy as that sounds. It misses the upper level winds, and for the human launch I wouldn't be at all surprised to find out that it is missing some weather criteria in the abort recovery zone as well.
- bryanlarsen 6y ago
  Eric Berger now has an article about the iffy weather: https://arstechnica.com/science/2020/05/spacex-may-launch-today-but-weather-is-a-huge-concern/ https://arstechnica.com/science/2020/05/spacex-may-launch-to...
S_A_P 6y ago
I get that you dont want to fly a giant rocket full of liquid oxygen and other explosives into a thunderstorm or hurricane, but what are some practical reasons for postponing a launch due to weather. As I (hardly) understand once you get high up in the atmosphere there is high wind even on a clear day, does rain matter that much?
- greedo 6y ago
  The weather needs to be good enough for a safe recovery downrange if there's an abort.
- ceejayoz 6y ago
  Various reasons, well explained here (in several answers, including one pointing out that Challenger blew up in part due to cold weather): https://space.stackexchange.com/questions/4967/why-are-rocket-launches-so-sensitive-to-weather https://space.stackexchange.com/questions/4967/why-are-rocke...
- danbr 6y ago
  I would think by far it’s for crew safety. Recovery due to an in-flight abort would be difficult in rough seas and weather if they had to be plucked out of the Atlantic. The aerostructure of the falcon 9 can only withstand so much side loading due to aerodynamic forces and wind before exceeding the operational limits of the rocket (body to keep it all from breaking apart, and the engines working hard to keep them on the correct trajectory).
  - S_A_P 6y ago
    Thank you for the answer. To those who downvoted- I normally don't comment on that, but damn it was an honest question and I admitted to having little knowledge on this and its not like I gave a hot take. Just wanting to learn something...
- ncallaway 6y ago
  First of all, weather is much more than just rain. One of the things that's monitored closely in the launch corridor are the upper atmospheric winds. Specifically the wind sheer in the upper atmosphere. Strong wind isn't typically a problem, but high wind sheer in the upper atmosphere can be problematic. Additionally, they check the weather in the entire recovery corridor. That is, anywhere that the capsule could end up during an abort. They want to make sure that if the capsule ends up in the ocean, the weather permits recovery operations. An abort and safe splash-down doesn't do us much good if the astronauts then drown because recovery operations are impaired due to weather. We're putting two lives on this rocket. A small delay is absolutely the right trade-off to reduce risk.

*Pending weather

On this note, does anybody know what the weather thresholds are that would cancel the launch? I mean, the current forecast suggests it will almost definitely be raining at 433pm Eastern, and wind will be around 10 mph. Is some amount of rain tolerable? How much wind is acceptable?

danbr 6y ago
Here’s some information on the Space Shuttle Weather Launch Commit Criteria. There are probably some added bits for the water recovery incase of an abort with Crew Dragon. https://www.nasa.gov/centers/kennedy/pdf/531435main_weather-rules-march2011.pdf https://www.nasa.gov/centers/kennedy/pdf/531435main_weather-... Edit: and for the falcon 9 (non crew) https://www.nasa.gov/pdf/649911main_051612_falcon9_weather_criteria.pdf https://www.nasa.gov/pdf/649911main_051612_falcon9_weather_c...

bryanlarsen 6y ago

Nominally a 60% chance of a go for launch weather, but according to Ken the Bin on Ars Technica, the weather in the abort corridor is poor so he expects a postponement.

lovelettr 6y ago
I live on Merritt Island. Our power has been out since 6:30 this morning due to intense storms in the area. That having been said, it is currently sunny and calm. Given what the weather has been like since Sunday I could see it being postponed. I hope the weather holds and gives a window.
gpm 6y ago
Typically that percent chance doesn't actually consider all the launch criteria as crazy as that sounds. It misses the upper level winds, and for the human launch I wouldn't be at all surprised to find out that it is missing some weather criteria in the abort recovery zone as well.
bryanlarsen 6y ago
Eric Berger now has an article about the iffy weather: https://arstechnica.com/science/2020/05/spacex-may-launch-today-but-weather-is-a-huge-concern/ https://arstechnica.com/science/2020/05/spacex-may-launch-to...

S_A_P 6y ago

I get that you dont want to fly a giant rocket full of liquid oxygen and other explosives into a thunderstorm or hurricane, but what are some practical reasons for postponing a launch due to weather. As I (hardly) understand once you get high up in the atmosphere there is high wind even on a clear day, does rain matter that much?

greedo 6y ago
The weather needs to be good enough for a safe recovery downrange if there's an abort.
ceejayoz 6y ago
Various reasons, well explained here (in several answers, including one pointing out that Challenger blew up in part due to cold weather): https://space.stackexchange.com/questions/4967/why-are-rocket-launches-so-sensitive-to-weather https://space.stackexchange.com/questions/4967/why-are-rocke...
danbr 6y ago
I would think by far it’s for crew safety. Recovery due to an in-flight abort would be difficult in rough seas and weather if they had to be plucked out of the Atlantic. The aerostructure of the falcon 9 can only withstand so much side loading due to aerodynamic forces and wind before exceeding the operational limits of the rocket (body to keep it all from breaking apart, and the engines working hard to keep them on the correct trajectory).
- S_A_P 6y ago
  Thank you for the answer. To those who downvoted- I normally don't comment on that, but damn it was an honest question and I admitted to having little knowledge on this and its not like I gave a hot take. Just wanting to learn something...
ncallaway 6y ago
First of all, weather is much more than just rain. One of the things that's monitored closely in the launch corridor are the upper atmospheric winds. Specifically the wind sheer in the upper atmosphere. Strong wind isn't typically a problem, but high wind sheer in the upper atmosphere can be problematic. Additionally, they check the weather in the entire recovery corridor. That is, anywhere that the capsule could end up during an abort. They want to make sure that if the capsule ends up in the ocean, the weather permits recovery operations. An abort and safe splash-down doesn't do us much good if the astronauts then drown because recovery operations are impaired due to weather. We're putting two lives on this rocket. A small delay is absolutely the right trade-off to reduce risk.