Weather outlook uncertain for Friday landing
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: December 19, 2006
An early landing forecast predicts a possibility for clouds and rain at the Kennedy Space Center for the shuttle Discovery's planned landing Friday. Slightly high crosswinds are expected at Edwards Air Force Base in California's Mojave Desert but conditions at Northrup Strip near White Sands, N.M., are expected to be acceptable. Conditions in California are expected to improve on Saturday, but Florida remains questionable.
Discovery only has enough hydrogen and oxygen on board for its electricity producing fuel cells to remain in orbit until Saturday at the latest. A decision to add a spacewalk to Discovery's mission Monday - and a decision to retain a final heat shield inspection Wednesday - pushed landing from Thursday to Friday. When just two landing days are available, NASA flight rules require a landing attempt at one of the agency's three sites on the first day to preserve the final landing opportunity for use in the event of mechanical problems or more bad weather.
NASA wants to avoid a landing in New Mexico if at all possible because it would take an estimated 45 days to bring in cranes and other equipment needed for mounting the shuttle atop a transport jet for return to Florida.
The heat shield inspection now planned for Wednesday is one of NASA's post-Columbia safety upgrades. It is intended to spot any micrometeoroid damage that might have occurred after the heat shield was inspected earlier in the mission. The threat of an entry-critical impact is believed to be in the neighborhood of 1-in-250. As such, many in the shuttle community believe the so-called "late inspection" is a high-priority objective.
But it is not officially listed as a high mission priority in NASA's flight documentation and agency officials earlier left open the option of reconsidering the late inspection and moving landing back to Thursday depending on the forecast. As of this writing, however, no such discussions have been held and managers said Monday it was unlikely the landing target would change.
Historically, based on actual weather in late December, there is only a 1 percent chance of bad weather that would preclude a landing at all three of NASA's three sites on the same day. There is only an 8 percent chance of bad weather at both Kennedy and Edwards.