RE: Shuttle reentry

From: Erkenswick, Tom M. (JSC-DM3) (tom.m.erkenswick@nasa.gov)
Date: Mon Nov 12 2007 - 17:54:33 UTC

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    From an AP article (I found a copy at http://www.miamiherald.com/news/nation/AP/story/296427.html):
    
    This 15-day mission is longer than most - and more stressful, too, with the astronauts forced to carry out repairs to a torn solar wing at the space station.  Crew fatigue is one reason the space agency decided to position Discovery for the first coast-to-coast re-entry since Columbia disintegrated over Texas in 2003...Discovery's original landing plan called for the ship to zoom up from the southwest over Central America and the Caribbean before landing in Florida. But that would have entailed a pre-dawn landing, and shuttle commander Pamela Melroy preferred a safer, easier touchdown in daylight, shuttle program manager Wayne Hale said.
    
    
    From a Houston Chronicle article that I can no longer find on their website:
    
    If plans for Wednesday's landing hold, Discovery will descend toward Florida from the northwestern United States, crossing the Midwest on a
    southeasterly course. It'll be the first time the shuttle crew has overflown the heartland since the 2003 Columbia tragedy.  When Discovery launched Oct. 23, the mission was to end with a pre-dawn landing in Florida. But the problems encountered by Discovery's crew with tears in a crucial space station solar panel prompted managers to extend the mission for a seven-hour repair spacewalk Saturday.  Now projected at 15 days, Discovery's space station assembly flight will be the longest to date.  Melroy asked mission managers to alter the flight plan for a daylight landing that would allow her crew more time to rest after four demanding spacewalks. The change altered the course of Discovery's descent.  "It's a basic fact that landing in the daylight is a safer and easier task than landing in the dark," said Hale. "This has become a long mission, and we want to make sure we set up the commander for the very best landing conditions that we possibly can."
    
    
    From Bill Harwood at CBS (http://www.cbsnews.com/network/news/space/120/STS-120_Archive.html):
    
    Discovery's original flight plan called for a pre-dawn entry and a so-called ascending node approach from southwest to northeast that would carry the shuttle across Central America, the Caribbean and then into Florida.  Ascending node entries require slightly less propellant than descending node, northwest-to-southeast approaches across the heartland of America.  Descending node trajectories also avoid high-altitude, high-latitude clouds of ice crystals that can form in summer months over the Northern Hemisphere.  But Discovery's mission was extended to cope with space station problems and NASA managers ultimately decided to switch to a descending node entry, one that will carry Discovery across the central United States for the first time since the 2003 Columbia disaster.  Shuttle Program Manager Wayne Hale said Monday that noctilucent clouds don't tend to form at this time of the year and given Discovery has plenty of propellant, "we opted for a descending rev deorbit this time, which allows us to land in the daytime."  "It's a basic fact that landing in the daylight is a safer and easier task than landing in the dark," he said. "And the commander on this flight has definitely  xpressed a preference for daylight landing."  In the wake of the Columbia disaster, NASA assessed the risk to the public posed by a returning shuttle that might suffer a catastrophic breakup.  "We have a standard public safety risk which is always computed and for an undamaged orbiter, this  onstitutes a very minimal ... risk to fly over the middle of the United States," Hale said. "The primary reason we're doing it is to allow us to have a daylight landing."  All shuttle pilots are trained to handle landing in daylight or darkness, but "I think most pilots prefer daylight landings," Hale said.  "I don't think this is a really strong impetus from the commander, but it is her preference."  "More than that, we are approaching a very long mission here,' he said.  "This will be the longest mission, I believe, by about 24, 26 hours, longer than any mission to the international space station and any
    mission other than a few we flew in the early 90s with what we called the extended duration orbiter pallet. We flew couple of very long missions with the EDO pallet."  "So this is becoming a long mission and we want to make sure we set up the commander for the very best landing conditions that we  possibly can."
    
    
    Tom
    
    
    -----Original Message-----
    From: Dale Ireland [mailto:direland@drdale.com] 
    Sent: Friday, November 09, 2007 12:19 PM
    To: 'SeeSat-L'
    Subject: Shuttle reentry
    
    Hello
    I haven't seen any reports of observations of the Shuttle reentry. I was
    wondering if anyone saw it in daylight and what the furthest observation
    from the landing was, in other words Nebraska? Wyoming? Georgia? It was
    cloudy when they passed over us in Seattle.
    Also, why did they reenter on a descending pass after so many years of
    ascending passes? They mentioned daylight landing but they have done night
    landings before I think. Their work/sleep cycle seemed different this
    mission, I wonder if it had anything to do with that, or the work/sleep
    cycle of the employees in Florida?
    Dale
    
    
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