Three types of weather that can delay an Atlas V rocket launch
11/15/2016, 7:22:13 AM
NOAA is preparing to launch their next-generation weather satellite into space, but the weather may play a role on when it takes off from the launch pad.
The GOES-R weather satellite will be hitching a ride into space aboard an Atlas V rocket, a type of rocket commonly used by NASA.
However, the flight may be delayed or postponed to a later date if the weather conditions are unfavorable.
The weather can be one of the most unpredictable factors when it comes to sending rockets into space as launch dates are set months in advance, too far out for meteorologists to predict exact conditions at the moment of liftoff accurately.
If any aspect of the weather is unfavorable, the launch will be postponed until the weather improves.
Specifically, the launch window for GOES-R will be open for two hours, so if the weather is not favorable at the time that the launch window opens, there is time for the weather to improve before the launch would be postponed and moved to another day.
With the GOES-R weather satellite having a price tag of $1.2 billion, it is crucial that the weather be favorable to reduce the risk of an unsuccessful launch.
The Air Force's 45th Weather Squadron provides the weather forecasts for launches fro Cape Canaveral, Florida, the location where most U.S.-based launches occur.
"Weather conditions dictate many of the activities around the launch site, not only the launches themselves," Steven Siceloff, a blog writer for NASA, said. "For instance, high winds can prevent crews from hoisting a spacecraft onto the top of a rocket. Thunderstorms can stop all activities on the launch pad."
Here are three different types of weather that can cause an AtlasV launch to be scrubbed:
Thunderstorms and lightning
Thunderstorms can be one of the most dangerous types of weather for rocket launches, especially in Florida where thunderstorms pop up nearly every day in the summer.
Rockets sitting on the launch pad are safe from lightning due to lightning rods around the pad, but after lift off, they are susceptible to being struck.
NASA has eight different launch weather criteria that relate to thunderstorms to ensure that an Atlas V rocket is safe from lightning throughout its entire launching process.
This includes making sure that there are no thunderstorms within a 10 nautical-mile radius of the launch pad and that there have not been any lightning strikes within a 10 nautical-mile radius of the launch pad in the 30 minutes prior to scheduled launch time.
A lightning strike almost spelled the end to the Apollo 12 mission before it even left the Earth's atmosphere.
Seconds after liftoff, the moon-bound rocket was struck by lightning, causing warning lights to illuminate and the spacecraft guidance system to lose its altitude reference.
Fortunately, the crew was able to get these systems back online quickly, and the rocket made it to and from the moon safely. However, this strike could have easily spelled an early end to the mission if issues were not able to be resolved in time.
Clouds and rain
Even if there is no lightning around the launch pad, any type of precipitation can force a launch to be scrubbed. This usually comes in the form of rain as it is rare for any type of frozen precipitation to fall along the coast of Florida.
Even if it is not raining, a thick layer of clouds could be all it takes for an Atlas V launch to be postponed.
Flying through a thin layer of clouds is generally harmless to the rocket, but if the cloud layer is greater than 4,500-feet-thick and extends into freezing temperatures, it can create issues that endanger the rocket's safety.
WindEven on a dry day with no rain, thunderstorms or clouds nearby, the weather could still cause a launch to be postponed.
High winds near the ground or high up in the atmosphere can force the launch to postponed as it may lead to control problems.
Determining if the winds near the ground are suitable for launch is rather easy. If weather observations near the launch pad reach or exceed 38 mph (33 knots), the launch will be scrubbed.
Determining if the winds higher in the atmosphere are favorable for launch is a little different.
Higher up in the atmosphere, the Air Force meteorologists analyze the wind shear, not necessarily the speed of the wind. Wind shear is the change of wind speed with altitude, and if there is too much wind shear, it can be too much for the rocket to handle.
In March, a Falcon 9 launch by SpaceX was scrubbed due to high wind shear. CEO Elon Musk said that the high shear "hits like a sledgehammer when [the rocket is] going up supersonic."
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Astronomy - June 14, 2019, 5:29:42 PM EDT