“Whenever any spacecraft is exposed to the elements, we will make sure the weather is compatible for the flight,”
PATRICK AIR FORCE BASE, Fla. – Tech. Sgt. Janel Uiterwyk, 45th Weather Squadron stands in front of Space Shuttle Endeavour which is mounted in a modified Boeing 747 at Edwards AFB, Calif. The 747 is used to ferry the shuttle to its original landing site if forced to land in another location. (U.S. Air Force photo by 1st Lt. Michael Jennings)
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PATRICK AIR FORCE BASE, Fla. -- Predicting snowfall or blinding sandstorms are not on the checklist for the 45th Space Wing Weather Squadron who methodically calculate and determine if the weather will threaten a future shuttle launch. However, rain, lightning, wind and cloud coverage are at the top of the “be on the look-out list” for any shuttle, missile or rocket that is destined for space.
Weather forecasting is one of the most significant tools used to calculate ideal conditions for a safe launch for both the crew and the shuttle. The 45th Weather Squadron spends countless hours planning and predicting the “hot spots,” because bad weather can instantly delay or “scrub” the launch.
The typical weather restrictions for a launch include wind, rain, high or low temperatures, and lightning. “We have temperature, wind and rain constraints due to the height of a vehicle,” said Capt. Mike McAleenan, launch weather officer. “All launches have the same constraints.”
High or low temperatures can cause a delay in a launch. Temperatures that go as high as 99 degrees Fahrenheit for more than thirty consecutive minutes are considered too high to launch a vehicle. On the other hand, very low temperatures that are 48 degrees Fahrenheit or lower also require an evaluation of the wind as a combined concern for the vehicle.
Sometimes, the experts are looking for more than one condition that could cause problems for the launch. “More complicated is the combined effect of the temperatures that involve wind, temperature and rain that have to be determined,” said Kathy Winters, shuttle launch weather officer. “We use a table to evaluate these conditions and average the results.”
Natural and triggered lightening restrictions include evaluating clouds and weather inside ten nautical miles of the launch pad. Along with lightning, rain can damage the shuttle as it increases in speed through the atmosphere. As rain hits the outside of the spacecraft, beads of water can hit like small rocks pelting the side. As rain freezes, ice forms on the craft’s surface. In the event the spacecraft’s surface is damaged or changed, the difference in the surface could affect the structure enough to dangerously change direction and turn it off course.
“Any cloud within 10 nautical miles is closely monitored,” Ms. Winters said. “We have all of these different measurements of miles to standardize all launches. The main focus is within the 10 mile range. The peak wind constraint is 23-34 knots, depending upon the direction of the wind.”
Heavy cloud coverage can adversely affect the visibility of the cameras that are designed to keep an “eye” on various parts of the shuttle. Space shuttle Discovery has new cameras that can be affected by bad weather, Captain McAleenan said. The cameras are used to view and detect any debris that falls off or around the shuttle during flight. There is a new external tank design for Discovery that officials will watch closely. Abysmal weather would prevent them from making those observations. Officials have also added more ground cameras to watch the shuttle as it lifts off. Cameras are set up along the coast, just north and south of the launch pad. In addition, two aircraft will fly to 55,000 feet to take photos from their perspective.
After a shuttle launch, the external tank of the orbiter is released into the ocean. Once it is retrieved, it travels on a barge up and down the Banana River to and from the Vehicle Assembly River Basin. The tank is offloaded and transported to the Vehicle Assembly Building. Recovery operations include the External Tank Transports from Michoud, Mississippi to port. “We also do post-launch work, such as the arrival of the external tank,” Ms. Winters said. “We give them an idea of what kind of weather to expect.”
It is critical to have the weather forecast and to understand the current conditions of the ocean during a external tank recovery. “The sea state, wind and other effects of the weather are faxed to the ship that is to recover the external tank,” Captain McAleenan said.
If the shuttle does not land at Kennedy Space Center, a “ferry flight” is scheduled to bring the shuttle back.
To transport the shuttle, the “ferry flight,” a modified Boeing 747, also known as the Shuttle Carrying Aircraft, is flown back to KSC with the shuttle on top. Weather conditions for this flight are also critical.
“We also have a Department of Defense Manned Spaceflight coordinator providing weather information to DDMS concerning the possibility of using the Transoceanic Abort Landing site,” the captain said. There are three TAL sites where weather forecasters take complete surface and upper-air observations and forward the information to DDMS. The three sites are located at Istres, France; and Zaragoza and Moron, Spain.
Air balloons are frequently used to gather weather updates. “Observation of the upper air with balloons will check the wind, temperature and rain of the area,” Ms. Winters said. We also provide weather updates to the DDMS to coordinate any search and rescue that may be necessary.”
Before they pass their forecast to officials, the weather team gathers bits of information from many sources to develop their idea of a picture perfect successful launch. “Whenever any spacecraft is exposed to the elements, we will make sure the weather is compatible for the flight,” Ms. Winters said. “We provide 24/7 weather resource protection.”