by Tech. Sgt. Lisa Luse
45th Space Wing Public Affairs
4/19/2005 – PATRICK AIR FORCE BASE, Fla. (AFPN) — Airmen of the 45th Weather Squadron here methodically calculate and determine if weather will threaten a future shuttle launch. Rain, lightning, wind and cloud coverage can instantly delay or “scrub” any shuttle, mission or rocket launch.
“We have temperature, wind and rain constraints (because of) the height of a vehicle,” said Capt. Mike McAleenan, the squadron’s launch weather officer. “All launches have the same constraints.”
Temperatures that go as high as 99 degrees for more than 30 consecutive minutes are considered too high to launch a vehicle. On the other hand, very low temperatures that are 48 degrees or lower also require an evaluation of the wind as a combined concern for the vehicle.
Sometimes, experts look 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 has to be determined,” said Kathy Winters, the squadron’s shuttle launch weather officer. “We use a table to evaluate these conditions and average the results.”
Natural and triggered lightning restrictions include evaluating clouds and weather within 11.5 miles of the launch pad. Along with lightning, the rain can also have a damaging affect on the shuttle as rain hits the outside of the spacecraft, the beads of water can be like small rocks hitting the side. As the rain freezes, ice forms on the surface. If the surface is damaged or changed, the difference could affect the structure enough to dangerously change direction and turn it off course, officials said.
“Any cloud within (11.5 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 (about 26 to 39 mph), depending upon the direction of the wind.”
Heavy cloud coverage can affect the visibility of the cameras designed to keep an “eye” on various parts of the shuttle. Space Shuttle Discovery has new cameras in place for its scheduled May 15 launch, Captain McAleenen said. It will be the first shuttle launch since Space Shuttle Columbia broke apart on re-entry in 2003.
The cameras view and detect any debris that may fall off or around the shuttle during flight. There is a new external fuel tank design for Discovery that officials said they will be closely watching.
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. There are also two aircraft that will fly at 55,000 feet to take photos from their perspective.
If the shuttle does not land at Kennedy Space Center, a “ferry flight” brings it back on top of a modified Boeing 747. Weather conditions for this flight are also critical.
There are three transoceanic abort landing sites where weather forecasters take complete surface and upper-air observations. 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 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.”
