STORY WRITTEN FOR & USED WITH PERMISSIONPosted: December 21, 2006The Discovery astonauts tested the shuttle's re-entry systems today and packed up for a trip back to Earth Friday to close out a successful space station re-wiring mission. The only question today is where the seven astronauts will land.Because of an earlier decision to add a spacewalk to Discovery's mission, the shuttle only has enough supplies to remain in orbit until Saturday at the latest. To provide a safety cushion in case of unexpected problems with the spacecrat, NASA flight rules call for a return to Earth Friday, weather permitting, at one of the agency's three landing sites - the Kennedy Space Center in Florida, Edwards Air Force Base, Calif., or Northrup Strip at White Sands Space Harbor, N.M.With marginal to bad weather expected in Florida and California, NASA may be facing its first New Mexico shuttle landing since 1982. Because White Sands is NASA's lowest-priority landing site, equipment needed to prepare the shuttle for a ferry flight back to Florida is not readily available and Discovery's return to Kennedy would be delayed four to six weeks.NASA managers are hoping the forecast changes and that the weather will permit a landing in either Florida or California. The astronauts have landing opportunities at all three sites on four successive orbits Friday starting with a deorbit burn on orbit 203 at 2:49 p.m. for a landing on KSC runway 15 at 3:56 p.m.Edwards, Northrup and Kennedy are available on the next orbit, for landings around 5:30 p.m. EST, and two more opportunities, at Edwards and White Sands, are available the orbit after that around 7 p.m. EST. A final Edwards opportunity is available one orbit later, around 8:36 p.m. EST.Ground track charts available .Entry data available .Entry flight director Norm Knight, overseeing his first shuttle landing, plans to brief reporters later today on his re-entry strategy. Depending on the actual weather Friday, he will focus the entry team's efforts on the best opportunities for Florida and California.The forecast for the Kennedy Space Center calls for scattered clouds at 2,000 and 5,000 feet and a broken deck at 10,000 feet. But there is a chance for a broken deck at 5,000 feet and a chance for showers within 30 nautical miles, both flight rule violations. Winds will be gusting to 22 knots, but the crosswind component for a landing on runway 15 is just 2 knots or so.At Edwards, clouds are no problem but winds out of 290 degrees gusting up to 22 knots will result in a crosswind of about 20 knots for a landing on runway 22/04. The daylight crosswind limit is 15 knots and while that can be raised to 17 if turbulence is mild, forecasters are predicting moderate turbulence at Edwards.The outlook for Northrup Strip at White Sands calls for light winds and broken cloud decks at 15,000 and 20,000 feet. It is "go" for landing.Here are all the possible landing opportunities on Friday (in EST and subject to slight change):FRIDAY, DEC. 2202:49 PM...12...18...02...Orbit 202 deorbit burn (TIG) for KSC landing03:56 PM...12...19...09...202 KSC landing04:19 PM...12...19...32...203 Edwards Air Force Base TIG05:27 PM...12...20...40...EAFB landing04:20 PM...12...19...33...203 Northrup Strip TIG05:27 PM...12...20...40...Northrup landing04:26 PM...12...19...39...203 KSC TIG05:32 PM...12...20...45...KSC landing05:54 PM...12...21...07...204 EAFB TIG07:00 PM...12...22...13...EAFB landing05:57 PM...12...21...10...204 Northrup TIG07:02 PM...12...22...15...Northrup landing07:32 PM...12...22...45...205 EAFB TIG08:36 PM...12...23...49...EAFB landingAssuming the weather provides any chance at all, shuttle commander Mark Polansky, pilot William Oefelein and their crewmates will shoot for a landing in Florida on the first opportunity. That would require a "go" from mission control around 2:30 p.m. for a three-minute 17-second rocket firing at 2:49 p.m., lowering the shuttle's velocity by about 222 mph. After a half-hour free fall, the shuttle would enter the discernible atmosphere at an altitude of 400,000 feet - entry interface - at around 3:24 p.m. At that point, the orbiter would be 5,100 miles from runway 15 at the Kennedy Space Center with touchdown expected at 3:56:12 p.m.Here are preliminary numbers for a KSC entry on orbit 202 (in EST; minor changes expected):EST...........EVENT10:49:00 AM...Begin deorbit timeline11:04:00 AM...Radiator stow11:14:00 AM...Mission specialists seat installation11:20:00 AM...Computers set for deorbit prep11:24:00 AM...Hydraulic system configuration11:49:00 AM...Flash evaporator checkout11:55:00 AM...Final payload deactivation12:09:00 PM...Payload bay doors closed12:19:00 PM...Mission control 'go' for OPS-3 entry software load12:29:00 PM...OPS-3 transition12:54:00 PM...Entry switchlist verification01:04:00 PM...Deorbit parameters update01:09:00 PM...Crew entry review01:24:00 PM...Commander, pilot don entry suits01:41:00 PM...Inertial measurement unit alignment01:49:00 PM...CDR/PLT strap in; mission specialists suit don02:06:00 PM...Shuttle steering check02:09:00 PM...Hydraulic power system prestart02:16:00 PM...Toilet deactivation02:24:00 PM...Vent doors closed for entry02:29:00 PM...Mission control 'go' for deorbit burn02:35:00 PM...Mission specialists seat ingress02:44:00 PM...Single APU start02:49:05 PM...Deorbit ignition02:52:22 PM...Deorbit burn complete (dV: 326 fps; dT: 3:17)03:24:19 PM...Entry interface03:29:19 PM...1st roll command to right03:36:33 PM...1st left-to-right roll reversal03:49:46 PM...Velocity less than mach 2.503:51:53 PM...Velocity less than mach 103:52:40 PM...253-degree left overhead turn to line up on runway03:56:12 PM...LandingVideo coverage for subscribers only:VIDEO:WIDESCREEN VIEW FROM PLAYALINDA BEACH TRACKER VIDEO:DISCOVERY'S LAUNCH THROUGH FUEL TANK SEPARATION VIDEO:SHORT CLIP OF DISCOVERY BLASTING OFF VIDEO:ASTRONAUTS DEPART QUARTERS FOR PAD VIDEO:CREW FINISHES DONNING SPACESUITS VIDEO:ASTRONAUTS IN DINING ROOM VIDEO:TIME-LAPSE MOVIE OF PAD GANTRY ROLLBACK VIDEO:LONGER LENGTH MOVIE OF THE SCRUB VIDEO:SCRUB CALLED DUE TO LOW CLOUDS VIDEO:ASTRONAUTS DEPART QUARTERS FOR PAD VIDEO:CREW FINISHES DONNING SPACESUITS VIDEO:ASTRONAUTS IN DINING ROOM THURSDAY VIDEO:PAD'S ROTATING SERVICE STRUCTURE ROLLED BACK VIDEO:POST-ARRIVAL COMMENTS FROM THE CREW VIDEO:ASTRONAUTS ARRIVE IN WAVE OF T-38 JETS VIDEO:BIOGRAPHIES OF THE DISCOVERY ASTRONAUTS VIDEO:NARRATED STS-116 MISSION PREVIEW MOVIE VIDEO:WEDNESDAY'S SHUTTLE BRIEFING IN ITS ENTIRETY BRIEFING SOUNDBITES:VIDEO:THE ISSUES DISCUSSED AT FRR VIDEO:NOT YOUR FATHER'S FRR VIDEO:READY TO RESUME NIGHT LAUNCHES VIDEO:LAUNCH PREPS PROCEEDING WELL VIDEO:YEAR-END ROLLOVER CONCERNS VIDEO:REASSESSING TANK FOAM RISK VIDEO:STATION SOLAR ARRAY DRIVE SYSTEM PROBLEM VIDEO:PRESSURIZATION PRECAUTIONS AT THE PAD VIDEO:OVERVIEW OF STS-116 MISSION VIDEO:SHUTTLE/ISS PROGRAM PERSPECTIVE VIDEO:PREVIEW OF MISSION'S SPACEWALKS VIDEO:ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING VIDEO:COVERAGE OF PRACTICE COUNTDOWN ACTIVITIES VIDEO:DISCOVERY ROLLS TO THE PAD VIDEO:DISCOVERY MATED TO TANK AND BOOSTERS VIDEO:SHUTTLE HOISTED VERTICALLY INSIDE VAB VIDEO:DISCOVERY HAULED FROM HANGAR TO VAB VIDEO:PORT 5 TRUSS PAYLOAD PACKED UP VIDEO:CREW VISITS KENNEDY SPACE CENTER VIDEO:EXTERNAL FUEL TANK MATED TO BOOSTERS MORE: John Glenn Mission PatchFree shipping to U.S. addresses!The historic first orbital flight by an American is marked by this commemorative patch for John Glenn and Friendship 7.Final Shuttle Mission PatchFree shipping to U.S. addresses!The crew emblem for the final space shuttle mission is available in our store. Get this piece of history!Celebrate the shuttle programFree shipping to U.S. addresses!This special commemorative patch marks the retirement of NASA's Space Shuttle Program. Available in our store!Anniversary Shuttle PatchFree shipping to U.S. addresses!This embroidered patch commemorates the 30th anniversary of the Space Shuttle Program. The design features the space shuttle Columbia's historic maiden flight of April 12, 1981.Mercury anniversaryFree shipping to U.S. addresses!Celebrate the 50th anniversary of Alan Shephard's historic Mercury mission with this collectors' item, the official commemorative embroidered patch.Fallen Heroes Patch CollectionThe official patches from Apollo 1, the shuttle Challenger and Columbia crews are available in the store. | | | | 2014 Spaceflight Now Inc.Astronauts to make solar array repair spacewalk today BY WILLIAM HARWOOD