Test

surprise of all - I felt I was upside down the entire first day. It wasn't a bad feeling, it was just an
unusual feeling."
Asked how she felt after landing, Morgan said: "The room still spins a little bit, but that's OK."
"What I really want to do is take what this experience was and figure out how we can do a better job
to help serve our students and our teachers in a way they want that will be more helpful to them,"
Morgan said. "And I would love to figure out how we can make more and more of these opportunities
available for more and more of our teachers."
With Endeavour back on the ground, NASA managers and engineers will carry out a detailed
inspection to precisely determine the extent of damage related to the foam strike while debating a
half-dozen potential near-term fixes to prevent insulation from falling off the liquid oxygen feedline
brackets during upcoming launches.
A bracket redesign already was in work, scheduled to debut on a tank four missions from now. The
question facing NASA is what to do about the next three flights, currently scheduled for launchings
Oct. 23, Dec. 6 and Feb. 14.
Shuttle Program Manager Wayne Hale said Monday it's too soon to say what impact work to recover
from Endeavour's unexpected foam debris incident might have on the upcoming schedule. But
Gerstenmaier said today that at this point, major delays do not appear to be in the cards.
"We're still pointed toward Oct. 23," Gerstenmaier said. "We have a meeting today going on to have
a look at the tank to see if there's anything we want to do in terms of modifying the tank ... or we
leave it the way it is and head for Oct. 23. But I think we're still clearly focused on the next mission
and we're ready to move forward."
From the local processing perspective, "it really and truly depends on how long we need to do the
analysis for the repair if it turns out to be necessary or not," said Launch Director Mike Leinbach.
"We were going to mate the external tank (and boosters) yesterday for the next mission, so we're in
kind of a holding pattern here. We've got several days to work with, so we're in no immediate danger
of delaying the next mission at all, that's certainly not in the cards. We have some time in the
schedule to make up as we go along. So it's going to depend on the results of the study, whether we
need to do a fix or not, how long we take to do that fix and then what that would translate into for
(processing)."
Hale said engineers are working on "five different options to improve the situation on the next tank.
We will expect there will be some readjustment to our schedule as we work through those options.
However, I believe that based on the discussions we've had, that our impacts to the next flight in
terms of the actual launch date of Oct. 23 will be small, we think we have plenty of time to evaluate
some changes and in fact implement them if we feel that they are well justified."
At NASA's traditional post-landing news conference, NASA Administrator Mike Griffin showed off
spectacular post-undocking pictures of the international space station, calling the unfinished lab
complex "one of the great accomplishments of mankind."
"We're building a space station here, one flight at a time, and while I appreciated the media's
attention on the ding in the tile, actually the orbiter overall was really pretty clean," he said. "We
had one kind of ugly ding and we paid appropriate attention to it. I would have liked to have seen

some media attention on what a magnificent accomplishment we're undertaking here. I think we're
doing pretty well with it."
Endeavour docked with the space station Aug. 10 and the next day, the astronauts installed a short
spacer segment on the right end of the station's main solar power truss. Two days later, Mastracchio
and Williams replaced a faulty stabilizing gyroscope on the station amid work to transfer 5,000
pounds of equipment and supplies to and from the lab complex. The astronauts used robot arms on
the shuttle and space station to attach a 7,000-pound equipment storage platform to the solar array
truss and staged a third spacewalk Aug. 15 to complete a variety of station assembly get-ahead
tasks.
Endeavour is the first shuttle equipped with a new station-to-shuttle power transfer system that
enabled the orbiter to plug into the space station's solar power grid. As a result, NASA managers
extended the flight three days and added a fourth spacewalk. Originally scheduled for last Friday,
the excursion was delayed one day while NASA managers debated whether to turn the excursion
into a tile repair spacewalk.
In the end, a repair was deemed unnecessary and Williams and space station flight engineer Clay
Anderson were cleared to carry out the originally planned EVA on Saturday. But the threat of
Hurricane Dean raised the possibility flight controllers at the Johnson Space Center might have to
evacuate. As a result, NASA managers shortened Saturday's spacewalk and moved undocking from
Monday to Sunday to get Endeavour back on the ground today.
As it turned out, Dean never threatened the Texas coast but by that point NASA was committed and
the crew returned to Earth today.
Flying backward over the Indian Ocean at a velocity of 5 miles per second, Kelly and Hobaugh fired
Endeavour's twin braking rockets at 11:25 a.m. for three minutes and 33 seconds, slowing the ship
by 246 mph and lowering the far side of its orbit into the atmosphere. A half-hour later, the shuttle
fell into the discernible atmosphere at an altitude of 76 miles. At that point, Endeavour was 5,020
miles from touchdown.
The shuttle's ground track carried it high above Central America just west of the Panama Canal on a
course carrying it across central Cuba and up the Florida peninsula to the Kennedy Space Center.
11:30 AM, 8/21/07, Update: Shuttle braking rockets fired; landing on tap at 12:32 p.m.
With good weather expected, shuttle commander Scott Kelly and pilot Charles Hobaugh fired
Endeavour's twin braking rockets at 11:25 a.m. for three minutes and 33 seconds, slowing the ship
by 246 mph and lowering the far side of its orbit into the atmosphere. A half-hour later, the shuttle
will reach the discernible atmosphere at an altitude of 76 miles. At that point, Endeavour will be
5,020 miles from touchdown.
The shuttle's ground track will carry it high above Central America on a course across Cuba and up
the Florida peninsula to the Kennedy Space Center.
Dropping below the speed of sound at an altitude of 48,000 feet above the landing site, Kelly will
take over manual control and guide the shuttle through a sweeping 210-degree left turn to line up on
runway 15. Touchdown is expected around 12:32:23 p.m.
6:00 AM, 8/21/07, Update: Astronauts set up for landing

The Endeavour astronauts are working through a busy re-entry day timeline this morning, preparing
the shuttle for landing at the Kennedy Space Center to close out a two-week space station assembly
mission. Forecasters are predicting generally favorable weather, but crosswinds could be close to
NASA's 15-knot limit.
Commander Scott Kelly, pilot Charles Hobaugh, Tracy Caldwell, Rick Mastracchio, Dave Williams,
Barbara Morgan and Al Drew were awakened at 4:36 a.m. by a recording of Simon and Garfunkle's
"Homeward Bound" beamed up from mission control.
"Good morning, Endeavour," astronaut Shannon Lucid radioed from Houston. "And the music this
morning was sent to all of you by all of your families in anticipation of a happy landing day."
"Well that's very nice of them to think of that, Shannon," Kelly replied. "Although it's been a short
two weeks, we've accomplished a lot and we still look very much forward to coming home today.
Thanks."
The deorbit timeline begins at 7:25 and barring a turn for the worse with the weather, the crew will
activate internal cooling and close Endeavour's cargo bay doors at 8:45 a.m.
Fresh out of a lengthy overhaul, Endeavour is the first space shuttle fully equipped with three Global
Positioning System satellite navigation receivers, an upgrade intended to improve the precision of
the orbiter's computer-controlled descent to the landing site.
Flying backward over the Indian Ocean at a velocity of 5 miles per second, Kelly and Hobaugh plan
to fire Endeavour's twin braking rockets at 11:25:12 a.m. for three minutes and 33 seconds, slowing
the ship by 246 mph and lowering the far side of its orbit into the atmosphere. A half-hour later, the
shuttle will reach the discernible atmosphere at an altitude of 76 miles. At that point, Endeavour will
be 5,020 miles from touchdown.
Two of Endeavour's heat-shield tiles, located on the belly of the craft behind the right main landing
gear door, were damaged 58 seconds after launch by a small piece of foam insulation that broke off
a liquid oxygen feedline bracket on the shuttle's external tank. After a lengthy analysis, NASA
managers decided the damage did not require any repairs and Endeavour was cleared for re-entry
as is.
"We agree absolutely 100 percent with the decision to not repair the damage," Kelly said during an
in-flight news conference. "We've had shuttles land with worse damage than this. We gave this a
very thorough look and I am very, very comfortable and there will be no extra concern in my mind
(during re-entry) due to this damage."
The shuttle's ground track will carry it high above Central America just west of the Panama Canal on
a course carrying it across central Cuba and up the Florida peninsula to the Kennedy Space Center.
Dropping below the speed of sound at an altitude of 48,000 feet above the landing site, Kelly will
take over manual control and guide the shuttle through a sweeping 210-degree left turn to line up on
runway 15. Touchdown around 12:32:23 a.m. will close out a 5.2-million-mile mission spanning 201
complete orbits since launch Aug. 8.
If the weather prohibits an on-time deorbit rocket firing, the astronauts will go around the world one
more time and make a second attempt 90 minutes later, at 1:00:12 p.m., for a landing at 2:06:44
p.m.

Kelly and his crewmates also have three landing opportunities today at Edwards Air Force Base in
California's Mojave Desert. But under NASA's standard entry day strategy, they only plan to attempt
a return to Florida. If the weather blocks both of today's Kennedy opportunities, the astronauts will
re-open the shuttle's payload bay doors, stay in orbit another day and try again Wednesday.
In that case, Edwards, which is already staffed, would be activated for use if necessary. The forecast
for Edwards calls for acceptable weather today through Thursday.
Here is a timeline for today's two Kennedy landing opportunities (in EDT):
EDT...........EVENTRev. 201 Deorbit to KSC07:25:12 AM...Begin deorbit timeline07:40:12
AM...Radiator stow07:50:12 AM...Mission specialists seat installation07:56:12 AM...Computers set
for deorbit prep08:00:12 AM...Hydraulic system configured for entry08:25:12 AM...Flash evaporator
cooling system checkout08:31:12 AM...Final payload deactivation08:45:12 AM...Payload bay doors
closed08:55:12 AM...Mission control 'go' for transition to OPS-3 software09:05:12 AM...OPS-3 entry
software loaded09:30:12 AM...Entry switchlist verification09:40:12 AM...Deorbit burn
update09:45:12 AM...Crew entry review10:00:12 AM...Commander/pilot don entry suits10:17:12
AM...Inertial measurement unit alignment10:25:12 AM...Mission specialists don entry suits10:42:12
AM...Braking rocket steering check10:45:12 AM...Hydraulic power unit (APU) prestart10:52:12
AM...Toilet deactivation11:00:12 AM...Payload bay vent doors closed for entry11:05:12 AM...Mission
control 'go' for deorbit burn11:11:12 AM...Astronaut seat ingress complete11:20:12 AM...Single APU
start11:25:12 AM...Deorbit ignition (dT: 3:33; dV: 246 mph)11:28:45 AM...Deorbit burn complete
(alt: 213 statute miles)12:00:25 PM...Atmospheric entry (alt 76 miles; range: 5,020 miles)12:05:24
PM...1st roll command to left12:20:32 PM...1st left-to-right roll reversal12:25:55 PM...Velocity less
than mach 2.5 (alt: 83,000 feet)12:28:03 PM...Velocity less than mach 1 (alt: 48,000 feet)12:29:12
PM...Shuttle on the HAC (alt: 33,000 feet; 210-degree left turn)12:32:23 PM...Landing on runway
15Rev. 202 Deorbit to KSC12:40:12 PM...Mission control 'go' for deorbit burn12:55:12 PM...Single
APU start01:00:12 PM...Deorbit ignition (dT: 3:33; dV: 246 mph)01:03:45 PM...Deorbit burn
complete (alt: 213 miles)01:34:47 PM...Atmospheric entry (alt: 76 miles; range to KSC: 5,095
miles)01:39:47 PM...1st roll command to right01:49:10 PM...1st right-to-left roll reversal02:00:08
PM...Velocity less than mach 2.5 (alt: 83,000 feet)02:02:12 PM...Velocity less than mach 1 (alt:
52,000 feet)02:03:07 PM...Shuttle on the HAC (alt: 39,000 feet; 260-degree left turn)02:06:44
PM...Landing on runway 15
10:15 PM, 8/20/07, Update: Hale optimistic about near-term external tank fix while long-term
upgrade is implemented; NASA focuses on Florida landing for shuttle Endeavour
NASA managers today formally cleared the shuttle Endeavour for re-entry and landing Tuesday,
weather permitting, to close out an action-packed space station assembly flight. Program managers
say a small-but-deep gouge in the shuttle's heat shield poses no threat to Endeavour or its crew. But
the jury is still out on what sort of near-term fix might be needed to keep shuttles flying until the
external tank problem that caused the damage can be eliminated.
"We will expect there will be some readjustment to our schedule as we work through those options,"
said Program Manager Wayne Hale. "However, I believe that based on the discussions we've had,
that our impacts to the next flight, in terms of the actual launch date of Oct. 23, will be small."
With Hurricane Dean no longer threatening mission control in Houston, NASA is no longer under
pressure to bring Endeavour down Tuesday, one way or the other, in Florida or backup landing sites
in California or New Mexico. Instead, the astronauts will only attempt to land at the Kennedy Space
Center and if the local weather doesn't cooperate, they will stay in orbit an additional day and try

again Wednesday. NASA no longer plans to staff White Sands Space Harbor, N.M.. But if Endeavour
doesn't make it home to Florida Tuesday, Edwards will be available for use as needed Wednesday.
Endeavour has enough on-board supplies to stay in orbit until Thursday, or even Friday in a worst-
case scenario. But flight controllers are hopeful it won't come to that. Forecasters are predicting
slightly out-of-limits crosswinds in Florida Tuesday, with just a slight chance of showers near the
shuttle's runway. The forecast for Edwards calls for high headwinds, but conditions are expected to
be within flight rule guidelines Tuesday through Thursday.
"We're proceeding with our nominal entry plans," Hale said. "Tomorrow, we will primarily look at
the Kennedy Space Center and if weather conditions are not conducive to getting back to Florida
with Endeavour, we most likely will wave off and attempt Kennedy on a subsequent day."
Commander Scott Kelly, pilot Charles Hobaugh, Tracy Caldwell, Rick Mastracchio, Dave Williams,
educator-astronaut Barbara Morgan and Al Drew have two opportunities on successive orbits to land
at Kennedy. The first opportunity calls for the shuttle's braking rockets to fire on orbit 201 at 11:25
a.m., setting up a touchdown on runway 15 at 12:32 p.m. The second deorbit opportunity comes at 1
p.m., for a landing at 2:06 p.m.
The gouge in Endeavour's belly was discovered after launch Aug. 8. Two heat-shield tiles were
damaged when a chunk of foam debris, possibly including ice, slammed into the orbiter 58 seconds
after liftoff. The impact gouged out an irregular pit crossing the boundary between two tiles,
measuring roughly two inches by three inches across and nearly penetrating the full 1.12-inch
thickness of the tile. A small, 1-inch by 0.2-inch gash at the bottom of the pit exposed an underlying
support pad just above the shuttle's aluminum skin.
The shuttle Columbia was destroyed Feb. 1, 2003, when it re-entered the atmosphere with a gaping
4- to 6-inch hole in the leading edge of its left wing. The wing melted from the inside out, the shuttle
broke apart above Texas and all seven crew members were killed. NASA managers do not view
Endeavour's gouge as a Columbia-class problem. Mission Management Team Chairman John
Shannon said the issue was simply whether re-entry heating might cause damage to the shuttle's
aluminum skin in the immediate area that would require time-consuming post-landing repairs.
Testing and computer models predict the underlying aluminum skin of the shuttle's right wing will
never get hotter than 350 degrees Fahrenheit, NASA's safety limit. At worst, Shannon said, a few
downstream tiles could be damaged, along with the two that were gouged out by the impact during
launch.
In the end, after nearly a week of around-the-clock testing and analysis, the Mission Management
Team cleared Endeavour for re-entry as is, deciding that a spacewalk repair was not necessary and
posed more risk to the shuttle than the gouge itself.
The damage was caused by three-hundredths of a pound of foam that fell away from a liquid oxygen
feedline support bracket. In an unlucky break, the foam struck an aft strut that helps hold the
shuttle to the external tank. Most of the debris survived that impact intact and ricocheted into the
shuttle. NASA already was designing a fix for the brackets, but the upgrade will not be ready until
the fourth flight from now.
Hale said today engineers are evaluating five near-term modifications to the feed line brackets,
adding he is optimistic the next shuttle flight, scheduled for launch Oct. 23, can stay roughly on
schedule. It will be more difficult to keep the flight after that on track, a high-priority mission to

launch a European research module. Currently scheduled for launch Dec. 6, the launch window
closes about one week later.
Today, Hale provided a snapshot of where the foam issue stands, how it might play out and why the
debate over Endeavour's heat shield gouge is very different from the limited analysis that preceded
Columbia's ill-fated re-entry.
But Hale would not predict where the foam will fit in NASA's probabilistic risk matrix and how that
might play into the agency's planning for the next shuttle flight. Here are Hale's opening remarks at
a news briefing Monday:
"When I was sitting in (entry flight director) Steve Stich's chair as entry flight director for 28 shuttle
landings, we never knew what the condition of the entry heat shield was," Hale said. "It was always
assumed to be good, we did no inspections, we did no analysis, we just trusted that it was a good
thing and we would be safe to enter. Now, we're smarter. And over the past four or five years we
have put together a great plan to inspect and make sure the heat shield is in good shape and if there
are any concerns, we have put together the equipment, the procedures, the planning and the entire
process to evaluate whether or not the heat shield is safe for re-entry and if it's not, to provide the
capability to repair.
"However, repairs are in and of themselves somethings hazardous to execute. So like so many things
in our business, it becomes a risk trade. At the final analysis, having allowed over 200 engineers and
specialists in the areas of thermal protection systems, aerothermal heating, to work hundreds of
hours, including 4,000-plus hours of super computer simulation (time) using well-anchored, test-
validated models, a series of extremely accurate and extensive tests in the re-entry simulators both
here at Johnson and at other facilities around the NASA team, and having been peer reviewed by
specialists in supersonic flight, hypersonic thermal environments and so forth, we can say with a
high degree of confidence that Endeavour is safe to come home without needing a repair.
"That does not mean that we're entirely happy with the situation and in fact, I had a discussion this
morning with the team about what our future steps are to make sure that the next flight and those
following it are safe to fly. Again, this was a problem that originally came from debris coming off the
external tank. After Columbia, we had a long discussion about how we could best eliminate the
hazards of debris coming off the external tank and it becomes very obvious in a very short order as
you look at the system, it's an inherent design situation with the space shuttle that we will never be
able to completely eliminate the potential of debris coming of the external tank, or some of the other
elements of the launch vehicle stack. And so there will never be a launch where we have zero risk.
"We will continue to improve as we go forward. What we did, however, do for return to flight and are
continuing to do to day, is to take a hard look at those areas where debris may be shed to try to
categorize them in order of their risk factor, in other words, which are the most serious risks, and to
methodically whittle away and reduce those risks by eliminating hazards one at a time. As you know,
we got quite a lot of risk reduction and hazard improvement with the first return to flight, STS-114.
We spent another period of time where we wanted to make another significant improvement and we
whittled that risk down significantly more by the time we flew the second return to flight (mission),
STS-121. We knew we were not finished at that point and in fact, set out on future redesigns. And
we have a number of improvements that are coming forward on a tank that we will fly about four
flights from now.
"We have three flights, however, with tanks that have not been modified. And in particular, one of
the areas on that external tank that we have already got a design in work for is off these liquid

oxygen feedline brackets that was the cause of the incident on Endeavour's launch. So we know that
four flights from now we have a good fix that will eliminate that hazard. The discussions I've been
having with the team in the last few days are what will we do with the next three tanks, and the next
three flights, until we get that final design into the fleet to, again, mitigate and reduce the hazard.
"Today we had about a two hour telecon with the tank designers and the folks that are working on
five different options to improve the situation on the next tank. We will expect there will be some
readjustment to our schedule as we work through those options. However, I believe that based on
the discussions we've had, that our impacts to the next flight in terms of the actual launch date of
Oct. 23 will be small, we think we have plenty of time to evaluate some changes and in fact
implement them if we feel that they are well justified.
"We are also looking at the further implications to the next flight because as we take time to prepare
this tank it does impact the schedule on the subsequent flight and we would really like to hold that
flight to the December launch window if we can do it safely. And I think that's the clue. As we look to
the manifest ahead of us, we can expect there will be challenges, whether they're from hurricanes or
from equipment that is causing us a problem on board the shuttle. However, we do have an amount
of time ahead of us, a skilled work force and a umber of options that will allow us to fly the manifest
as it's been laid out and complete the international space station with a significant margin of time
before the date that the president and the congress have directed us to retire the space shuttle
vehicle."
Going into Endeavour's flight, Hale said engineers viewed the risk posed by foam falling off oxygen
feedline brackets as "rather low."
"In the analysis, it was assumed that if the aerodynamics carried this foam down to the attach
bracket of the external tank and struck it, that the foam would come apart and that would be the end
of the hazard. And in fact what we saw on the video ... we saw this piece of foam strike this strut
which is angled at a 30- to 45-degree angle to the flight path and ricochet off and hit the bottom of
the orbiter, it's clear as day.
"We didn't think that could happen before. So we would have told you that was a non-credible, non-
possible thing to happen. Therefore, no risk, at least in a rebound case. Clearly, we're smarter now
than we were a couple of weeks ago and we're looking very hard at those particular locations and
those particular aerodynamic paths that might lead this foam or foam and ice combination to hit the
strut and bounce off and strike the underside of the orbiter. So we have a more sophisticated risk
analysis in work. That's why I think the risk is probably higher than we had characterized before."
But Hale said he does not believe the problem represents a "probable-catastrophic" threat to the
shuttle, a level of risk that is not generally considered acceptable for flight.
"It is currently not categorized as probable-catastrophic," Hale said. "It is my belief that it will not be
classified as probable-catastrophic. The risk assessment people, however, are off doing their work
and we do not have the final numbers back from that. And we will be informed by that analysis when
it comes in. So, it's under review."
11:15 AM, 8/20/07, Update: NASA will staff KSC and Edwards for Tuesday landing; weather update
The 11 a.m. forecast from the National Hurricane Center continues to show Hurricane Dean on a
track that will take it into central Mexico late Wednesday. Assuming no major changes that would
threaten mission control in Houston, NASA will attempt to bring the shuttle Endeavour back to

Florida on Tuesday. But depending on the forecast for Wednesday, entry flight director Steve Stich
could opt to divert the crew to Edwards Air Force Base, Calif., if the KSC weather doesn't cooperate.
"Hurricane Dean is kind of trending away, so we don't think that's going to be a factor," astronaut
Chris Ferguson radioed the crew from mission control around 10:35 a.m. "We're still keeping our
options open, however.
"For landing weather at the Cape tomorrow," he continued, "the weather is forecast to be pretty
good. They're calling few (clouds) at 3,000 and few at 25,000. They are still, however, carrying a
slight chance of rain showers and as we look at the radar here this morning, they seem to be
sporadically building along the coast. So I'm sure that'll be a bit of a touch-and-go situation. But so
far, it's looking pretty good.
"Probably the biggest issue right now might be the crosswinds," Ferguson said. "Right now, they're
calling for, it looks like, one zero (100 degrees) at 10 (knots), peak to 18."
That translates into a crosswind component of nearly 14 knots. NASA's end-of-mission - EOM - flight
rules forbid daylight landings in crosswinds higher than 15 knots.
"So for that reason, we will still continue to bring Edwards up most likely for tomorrow only because
in addition to the winds at KSC, the end-of-mission plus one winds (Wednesday) at Edwards are
forecast to grow and the winds at KSC will remain high for EOM plus one. So in a nutshell, weather's
looking good at both KSC and at Edwards. Crosswinds may be an issue and for that reason, we'll
have two sites most likely available for tomorrow."
A detailed re-entry timeline for Tuesday, Wednesday and Thursday, along with an updated weather
forecast, will be posted here after today's mission status briefing.
6:30 AM, 8/20/07, Update: Crew preps for entry
The Endeavour astronauts are preparing the shuttle for landing Tuesday, packing up equipment,
testing the ship's re-entry systems and enjoying a final few hours of off-duty time this afternoon.
Canadian astronaut Dave Williams, commander Scott Kelly and Barbara Morgan plan to participate
in a Canadian Space Agency VIP/education event at 11:46 a.m., the final such event of the mission.
The astronauts were awakened for their final full day in space at 4:37 a.m. by a recording of "Flying"
by the Long John Baldry Trio, a Canadian group, beamed up from mission control.
"Good morning, Endeavour, and a special good morning to Dave today, astronaut Shannon Lucid
called from Houston.
"And Houston, Endeavour, good morning," Williams replied. "That's a great song to hear for a day
before we come back to land."
Today's mission status briefing with entry flight director Steve Stich is planned for 2:30 p.m. and a
final Mission Management Team update is scheduled for 4 p.m. Among the topics will be the results
of Sunday's final heat shield inspection.
Here is an updated timeline of events (include revision Q of the NASA television schedule; in EDT
and mission elapsed time):

EDT........DD...HH...MM...EVENTMonday, 08/20/0704:37 AM...11...10...00...Crew wakeup07:42
AM...11...13...05...Cabin stow begins07:52 AM...11...13...15...Flight control system checkout (began
early)09:12 AM...11...14...35...Maneuvering thruster hot fire test09:27 AM...11...14...50...Deorbit
review11:47 AM...11...17...10...Canadian Space Agency VIP/educational event12:57
PM...11...18...20...PILOT landing simulator practice01:07 PM...11...18...30...Spacehab entry
preps01:52 PM...11...19...15...Crew meal02:30 PM...11...19...54...Mission status briefing on
NTV03:12 PM...11...20...35...Crew off duty04:00 PM...11...21...24...Post-MMT briefing on NASA
TV05:27 PM...11...22...50...Ergometer stow05:53 PM...11...23...16...Orbit adjust rocket firing05:57
PM...11...23...20...KU-band antenna stow08:37 PM...12...02...00...Crew sleep beginsTuesday,
08/21/0704:37 AM...12...10...00...Crew wakeup06:32 AM...12...11...55...Group B computer
powerup06:47 AM...12...12...10...Inertial measurement unit alignment07:27
AM...12...12...50...Deorbit timeline begins11:25 AM...12...16...48...Deorbit ignition (dT: 3:33; dV: 246
mph)12:01 PM...12...17...24...Entry interface (alt: 400,000 feet)12:05 PM...12...17...28...First left roll
command12:21 PM...12...17...44...Left-to-right roll reversal12:26 PM...12...17...49...Mach 2.512:28
PM...12...17...51...Mach 112:30 PM...12...17...53...Shuttle banks to line up on runway 1512:32
PM...12...17...55...LandingThe 5 a.m. forecast from the National Hurricane Center continues to show
Hurricane Dean on a track that will take it into central Mexico late Wednesday. Assuming no major
changes that would threaten mission control in Houston, NASA likely will attempt to bring
Endeavour back to Florida on Tuesday and, if the weather at the Kennedy Space Center doesn't
cooperate, extend the mission a day and try again on Wednesday.
The Sunday evening forecast from the Spaceflight Meteorology Group at the Johnson Space Center
called for good weather at Kennedy on Tuesday, with scattered clouds at 3,000 and 10,000 feet and
winds out of 110 degrees at 10 knots with gusts to 17. That translates into a maximum crosswind of
about 11 knots, well below NASA's safety limit.
A detailed re-entry timeline for Tuesday, Wednesday and Thursday, along with an updated weather
forecast, will be posted here after today's mission status briefing.
4:50 PM, 8/19/07, Update: Endeavour undocks from space station; Hurricane Dean less threatening
to mission control; White Sands out of landing strategy
The Endeavour astronauts undocked from the international space station today and carried out a
final inspection of the shuttle's carbon composite nose cap and wing leading edge panels to make
sure the ship is ready for re-entry and landing Tuesday to close out a dramatic station assembly
mission.
"Undocking, in a word, really was flawless, it was completely by the book, absolutely picture
perfect," said lead flight director Matt Abbott. "Looking ahead to tomorrow, the crew wakes up at
3:30 a.m. (Central Time). It'll be pretty much a standard end-of-mission-minus-one day, with reaction
control system hotfire checks and the flight control system checkout activities and cabin stowage.
Tuesday is now our planned landing day.
Forecasters are predicting generally good weather at the Kennedy Space Center and at NASA's
favored backup landing site, Edwards Air Force Base, Calif.
"KSC weather permitting in Florida, the plan is to go into KSC on Tuesday and of course, we do have
some extension days beyond that, weather permitting here in Houston as we continue to watch the
track of Hurricane Dean."
NASA originally planned for Endeavour's crew to undock Monday and land Wednesday. But a fourth

and final spacewalk was cut short Saturday and the crew was ordered to undock and land a day
early because of the possibility Hurricane Dean could force flight controllers to evacuate the Johnson
Space Center in Houston. While NASA has contingency plans in place to control a shuttle flight from
Kennedy, engineers would not enjoy the normal staffing levels and computer processing power.
Moving landing up one day, NASA hoped to ensure normal mission control operations for at least
one landing opportunity.
Because of the possibility of an evacuation later in the week, mission managers decided over the
weekend to staff all three shuttle landing sites Tuesday - Kennedy, Edwards and White Sands Space
Harbor, N.M. If JSC was threatened, the plan was to bring Endeavour down at one of those sites.
But Hurricane Dean is now tracking well south of Houston, an evacuation is not imminent and with
good weather expected in Florida and California's Mojave Desert, mission managers today dropped
White Sands from their landing plan.
"The latest track from the National Hurricane Center is favorable for the Johnson Space Center,"
said John Shannon, chairman of NASA's Mission Management Team. "It looks like it'll be passing by
Jamaica today and heading for the Yucatan Peninsula and then into central Mexico. There is still
uncertainty with a storm like this, but right now it's looking pretty good from our standpoint. The
Johnson Space Center will be open for normal operations tomorrow. ... We will meet again tomorrow
but the threat is certainly somewhat less than it was the last two days."
As a result, he said, "we're not going to execute any of those (contingency) plans right now. We're
just going to wait. There's not going to be a change to the flight control team manning, we're not
going to be sending people out to Florida right now, we're going to stand by a little bit.
"We'll come in tomorrow and we'll talk about the hurricane, we'll talk about the weather at the
landing sites," Shannon said. "I think for Monday, we would probably leave all of our support for
Edwards and for the Kennedy Space Center in place and then on Tuesday, we'd be one day smarter
on where the hurricane is really going. It's possible Tuesday morning we would end up not
exercising an Edwards option if the Kennedy Space Center was not go and end up going around to
Wednesday to try and get into the cape."
NASA landing charts and
data:http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts118/landing.htmlHere are
updated deorbit and landing times for Tuesday, Wednesday and Thursday at the Kennedy Space
Center and Edwards Air Force Base (in EDT):
ORBIT.SITE..DEORBIT....LANDINGTuesday, 08/21/07201...KSC...11:25 AM...12:32
PM202...KSC...01:00 PM...02:06 PM203...EDW...02:30 PM...03:37 PM204...EDW...04:06 PM...05:11
PM205...EDW...05:43 PM...06:48 PMWednesday, 08/22/07217...KSC...11:52 AM...12:54
PM218...KSC...01:27 PM...02:29 PM219...EDW...02:57 PM...03:59 PM220...EDW...04:33 PM...05:35
PMThursday, 08/23/07232...KSC...10:40 AM...11:42 AM233...KSC...12:15 PM...01:17
PM234...EDW...01:45 PM...02:47 PM235...EDW...03:20 PM...04:22 PM236...EDW...04:57 PM...05:58
PM"We've got two more days to go in the mission, so it's not over yet," Abbott said. "We've got to
stay focused, but we're looking forward to a safe and successful couple of days and then an entry
and landing on Tuesday."
Endeavour undocked from the international space station today at 7:56 a.m. as the two spacecraft
sailed 210 miles above the south Pacific Ocean.

"Physical separation, Houston," one of the shuttle astronauts radioed as powerful springs pushed the
two spacecraft apart.
As the shuttle slowly pulled away directly in front of the lab complex, station commander Fyodor
Yurchikhin radioed: "Endeavour, from ISS. Endeavour departure." Following naval tradition, he then
rang the ship's bell in the Destiny laboratory module.
"Thanks for everything, Scott and the Endeavour crew," station flight engineer Clay Anderson said to
shuttle commander Scott Kelly. "Godspeed, I was proud to be a part of STS-118."
"And Endeavour, have a good landing," station flight engineer Oleg Kotov radioed.
"And to the ISS crew, we couldn't have gotten everything we accomplished without you guys," Kelly
replied. "We look forward to seeing you back on planet Earth."
Endeavour pulled away to a distance of about 400 feet in front of the station before looping up and
passing directly above it. From there, the shuttle fell behind and slowly left the immediate area.
With undocking complete, the major item on the crew's agenda today was a final heat shield
inspection to make sure Endeavour's reinforced carbon carbon nose cap and wing leading edge
panels have not suffered any damage from orbital debris or micrometeoroids since a similar
inspection was carried out the day after launch.
No obvious damage was visible in downlinked television views of the survey, but it will take
engineers a full day to assess the data and make a final determination.
"Just about every flight, we do see MMOD (micrometeoroid/orbital debris) damage on the wing
leading edge and nose cap," Shannon said. "They're very small scrapes, very small pits in the silica
carbide gray outer layer, but not down to the carbon. Matter of fact, I think on the last flight we had
17 small indications. Post flight, they go over it with high magnification and look for anything like
that. That is just a function of flying in space. You have very small particles that can impact you. It
would take a fairly significant one to affect us but it's not a zero probability, that's why we do the
late inspection."
Impact sensors mounted directly behind Endeavour's leading edge panels have recorded 16 events
corresponding to shocks ranging in strength from 0.5 to 2 Gs. Similar shocks have been recorded on
previous post-Columbia shuttle flights. Engineers believe the events may be associated with thermal
stress as the shuttle's structure responds to changes in temperature.
6:00 AM, 8/19/07, Update: Shuttle crew prepares for undocking
The Endeavour astronauts are preparing to undock from the international space station today after a
busy, at times dramatic, nine days of orbital construction and supply transfer work. Hatches
between the two spacecraft were closed Saturday and if all goes well, the shuttle will undock at 7:57
a.m.
Because the crew has had only a few hours of off-duty time since the mission began, flight
controllers designed a straight-forward fly away, eliminating a slow loop around the station for photo
documentation to give the astronauts a few more hours off at the end of the day. The second of two
rocket firings at 8:54 a.m. will complete the undocking and separation procedure.

Along with beginning the process of packing up for landing Tuesday, the astronauts plan to carry out
a final inspection of the shuttle's nose cap and wing leading edge panels, which experience the most
extreme heating during re-entry. A similar inspection was carried out Aug. 9, the day after launch, to
look for signs of ascent impact damage. This time around, the astronauts are looking for any signs of
damage from space debris or micrometeoroids that might have occurred since the initial inspection.
The late inspection is scheduled to begin around 10:15 a.m. A laser scanner and high-resolution
camera on the end of a 50-foot-long boom attached to the shuttle's robot arm will be slowly moved
back and forth along the right wing leading edge panels, the carbon composite nose cap and then
the left wing. The work should be finished by around 2:30 p.m.
Impact sensors mounted directly behind the leading edge panels have recorded 16 events
corresponding to shocks ranging in strength from 0.5 to 2 Gs. Similar shocks have been recorded on
previous post-Columbia shuttle flights, but no obvious signs of actual impacts were detected during
late inspection. Engineers believe the events may be associated with thermal stress as the shuttle's
structure responds to changes in temperature.
"The magnitudes seen on STS-118 have been very similar to previous missions although there has
been a 50 percent increase in the number of indications compared to previous flights," NASA's
Mission Management Team told the astronauts in a note uplinked Saturday as part of the crew's
daily execute package. "This may be attributed to the fact that improvements have been made to the
system to provide data simultaneously for both wings for longer periods of time and at colder
temperatures. For example, the monitoring time during STS-118 before docking is twice as much as
STS-117 and about three times that of STS-116.
"Most of the indications, a majority of which occurred on the port wing, were clustered early in the
mission prior to and after docking. A few of the wing leading edge indications on previous flights
have been correlated to minor impacts found on the wing leading edge panels during post-landing
inspections. Many of the other WLE (wing leading edge) sensor indications from previous flights
have not been correlated with anything including thruster firings, other mission events, thermal
day/night cycles, etc. Many theories exist as to what has caused an increased number of wing
leading edge indications on STS-118 including MMOD and the Perseid meteor activity. However, no
definitive correlations were found between the Perseids and the increased indications since half of
the indications occurred during Earth blockage. Only a single indication occurred during the
Perseids peak with both wings being continuously monitored. Obviously, the MMOD
(micrometeoroid/orbital debris) concern is the primary reason for executing the late inspection."
Here is an updated timeline of today's activity in space (in EDT and mission elapsed time; note:
NASA rounds down to the nearest minute; this page rounds up or down as required):
EDT........DD...HH...MM...EVENT08/19/0704:37 AM...10...10...00...STS crew wakeup06:17
AM...10...11...40...Group B computer power up06:33 AM...10...11...56...Sunrise07:01
AM...10...12...24...Noon07:12 AM...10...12...35...Undocking timeline begins07:28
AM...10...12...51...Sunset07:57 AM...10...13...20...Undocking07:57 AM...10...13...20...Initial orbiter
separation (+10 seconds)07:58 AM...10...13...21...Space station holds current attitude08:01
AM...10...13...24...Range: 50 feet; reselect -X jets08:02 AM...10...13...25...Range: 75 feet; low-Z
jets08:05 AM...10...13...28...Sunrise08:26 AM...10...13...49...Range: 400 feet08:26
AM...10...13...49...Separation burn No. 108:32 AM...10...13...55...Range: 600 feet08:32
AM...10...13...55...Noon08:54 AM...10...14...17...Separation burn No. 209:00
AM...10...14...23...Sunset09:02 AM...10...14...25...ISS: Shuttle docking port depressurization09:07
AM...10...14...30...Group B computer power down09:07 AM...10...14...30...Post-undocking laptop

computer reconfiguration09:07 AM...10...14...30...Supply transfer cleanup09:27
AM...10...14...50...Shuttle arm (SRMS) unberths inspection boom10:17 AM...10...15...40...Starboard
wing survey10:52 AM...10...16...15...Spacesuit install in airlock11:02 AM...10...16...25...EVA tool
stow11:57 AM...10...17...20...Nose cap survey12:57 PM...10...18...20...Port wing survey01:27
PM...10...18...50...ISS: Shuttle docking port leak check02:42 PM...10...20...05...Inspection boom
berthing03:17 PM...10...20...40...SRMS power down03:27 PM...10...20...50...Laser data
downlink03:32 PM...10...20...55...Crew meal04:32 PM...10...21...55...Crew off duty08:37
PM...11...02...00...STS crew sleep beginsThe Mission Management Team continues to monitor the
progress of Hurricane Dean. Concern about Dean's track and the possibility mission control at the
Johnson Space Center might have to be evacuated prompted NASA to move undocking up one day
and bring Endeavour back to Earth Tuesday - one day early - to ensure a Houston-controlled re-
entry.
On Sunday, the MMT decided that if Hurricane Dean threatened the Johnson Space Center,
Endeavour would land Tuesday at one of NASA's three shuttle landing facilities - the Kennedy Space
Center in Florida, Edwards Air Force Base, Calif., or White Sands Space Harbor, N.M. If the storm
did not pose a threat, the astronauts would attempt to land at Kennedy on Tuesday and, if conditions
there were not acceptable, remain in orbit another day and try again on Wednesday. The shuttle has
enough on-board supplies to remain in orbit until Friday if worse comes to worse.
Over the past few days, Hurricane Dean's predicted path has been creeping south and today's 5 a.m.
forecast from the National Hurricane Center showed Dean crossing the heart of the Yucatan
Peninsula early Tuesday before hitting the central Mexican coast late Wednesday or early Thursday.
The cone of uncertainty has moved well away from Houston.
If the storm stays on that track, NASA likely will execute its normal entry strategy, focusing solely on
a Florida landing Tuesday and, barring that, a landing at Kennedy or Edwards on Wednesday. The
early forecast for Tuesday at Kennedy calls for general favorable conditions with a slight chance of
showers in the area. Touchdown is targeted for 12:32 p.m.
6:19 PM, 8/18/07, Update: Shuttle-station hatches closed; undocking on tap Sunday, landing
Tuesday
The Endeavour astronauts staged a final, abbreviated spacewalk today and closed hatches between
the shuttle and the international space station to set the stage for undocking early Sunday and
landing Tuesday - a day early because of concern about Hurricane Dean - to close out a dramatic
station assembly mission.
NASA's Mission Management Team met today and after evaluating the hurricane's predicted track
and speed, decided that if the storm threatens to force an evacuation of the Johnson Space Center in
Houston, flight controllers in Texas will stay long enough to oversee a Tuesday landing in Florida or,
if bad weather develops at Kennedy, at Edwards Air Force Base, Calf., or White Sands Space Harbor,
N.M.
If the hurricane does not threaten Johnson, the astronauts will still attempt a landing at Kennedy on
Tuesday but in that case, if bad weather crops up in Florida, they will stay in orbit another day and
try again on Wednesday. The shuttle has enough on-board supplies to stay in orbit until Friday, but
the last day is always held in reserve in case of last-minute technical problems. Cain said NASA
hopes to have the shuttle on the ground by Thursday at the latest.
"End of mission day is now Tuesday," said LeRoy Cain, chairman of NASA's Mission Management

Team for launch and landing. "Tuesday is our first landing day. So we have now changed our plan so
that instead of end-of-mission being on Wednesday, end-of-mission is on Tuesday. The only thing to
think about that might be different is whether or not the storm might be threatening us when we get
to the late-Monday, early-Tuesday timeframe. Essentially, if the storm is indeed threatening (the
Johnson Space Center) area, we will have all three landing sites called up Tuesday and we will land
somewhere on Tuesday. And that'll be the going-in plan."
Canadian astronaut Dave Williams and Expedition 15 flight engineer Clay Anderson staged a five-
hour and two-minute spacewalk today to finish up a few final space station assembly tasks. As soon
as they were back aboard, the combined crews rushed to finish last-minute equipment transfer work
and then gathered in the Destiny laboratory module for a final farewell just after 5 p.m.
"Unfortunately, time has only one meaning here, it comes very fast," said Expedition 15 commander
Fyodor Yurchikhin. "We had some problems but (we did very well), very good job. Thank you very
much for everybody. We will be here just a little more than two months. Come back again!"
"We got a lot accomplished," shuttle commander Scott Kelly agreed. "We couldn't have done all that
stuff without you guys, we really appreciate your help and it's great being part of one big team
between the shuttle crew and the station crew. Thanks."
The two crews then shared hugs and handshakes before the Endeavour astronauts floated back
aboard the space shuttle. Hatches between the two spacecraft were closed around 5:10 p.m. If all
goes well, Endeavour will undock at 7:57 a.m. Sunday. Here is an updated timeline of key events (in
EDT and mission elapsed time):
EDT........DD...HH...MM...EVENT08/19/0704:37 AM...10...10...00...Shuttle crew wakeup06:33
AM...10...11...56...Sunrise06:37 AM...10...12...00...Group B computer power up07:01
AM...10...12...24...Noon07:12 AM...10...12...35...Undocking timeline begins07:28
AM...10...12...51...Sunset07:57 AM...10...13...20...UNDOCKING07:57 AM...10...13...20...Initial
orbiter separation (+10 seconds)07:58 AM...10...13...21...ISS holds current attitude08:01
AM...10...13...24...Range: 50 feet08:02 AM...10...13...25...Range: 75 feet08:05
AM...10...13...28...Sunrise08:26 AM...10...13...49...Range: 400 feet08:26
AM...10...13...49...Separation burn No. 108:32 AM...10...13...55...Range: 600 feet08:32
AM...10...13...55...Noon08:54 AM...10...14...17...Separation burn No. 209:00
AM...10...14...23...Sunset09:02 AM...10...14...25...ISS: Station docking port depressurization09:07
AM...10...14...30...Group B computer power down09:07 AM...10...14...30...Post-undocking laptop
reconfiguration09:07 AM...10...14...30...Supply transfer cleanup09:32 AM...10...14...55...Shuttle arm
(SRMS) unberths heat shield inspection boom (OBSS)10:22 AM...10...15...45...OBSS starboard wing
survey10:52 AM...10...16...15...Spacesuit install in airlock11:07 AM...10...16...30...EVA tool
stow12:02 PM...10...17...25...OBSS nose cap survey01:02 PM...10...18...25...OBSS port wing
survey01:27 PM...10...18...50...ISS: docking port leak check02:47 PM...10...20...10...OBSS
berthing03:22 PM...10...20...45...SRMS power down03:37 PM...10...21...00...Crew meal03:42
PM...10...21...05...Laser data downlink04:37 PM...10...22...00...Crew off duty08:37
PM...11...02...00...Shuttle crew sleep beginsThe astronauts originally planned to carry out a full-
duration spacewalk today and finish up equipment and supply transfers to and from the lab complex
Sunday. Hatches between Endeavour and the station were scheduled to be closed Sunday night to
set the stage for undocking Monday. A now-routine post-Columbia final heat shield inspection was
on tap Monday afternoon and the crew planned to pack up and test the shuttle's re-entry systems
Tuesday. Touchdown at the Kennedy Space Center was targeted for around 12:52 p.m. Wednesday.
But Hurricane Dean has thrown a wrench into those plans because NASA may be forced to evacuate

the Johnson Space Center early next week. If so, and if landing remained targeted for Wednesday,
the agency would have to set up an emergency mission control center at the Kennedy Space Center.
While controlling a shuttle from Kennedy is part of a long-established contingency plan, NASA would
have to rely on a much smaller team and give up some of its ability to monitor the orbiter's myriad
systems. By moving landing up a day, NASA likely could ensure a normal JSC-controlled re-entry.
"If by the time we show up in the late-Monday, early-Tuesday timeframe the storm is not threatening
the area and looks like it is not going to be a threat, then the entry team will execute the normal
deorbit-and-entry mission planning, which is typically on the first end-of-mission day we will try to
land at Kennedy Space Center in Florida and if we're not able to - and again, if the storm is not
threatening us (in Houston) - in all likelihood we would elect to go around and make a landing
attempt on Wednesday."
The forecast for Tuesday calls for generally good weather in Florida with only a chance of showers in
the area.
"It's really dependent on what the storm does," Cain said. "We are prepared to land on Tuesday if
the storm is threatening us, we've set ourselves up to be able to do that. We will still attempt to land
on Tuesday even if the storm is not threatening us. However, if we are not able to land at Kennedy
Space Center on Tuesday and the storm is not threatening us then we will be in our normal landing
operations and we would go around and show up on Wednesday and try to land at Kennedy."
Williams and Anderson accomplished three primary objectives during today's spacewalk. They
installed clamps on the station's main solar array truss that will be used next year to temporarily
hold a shuttle heat shield inspection boom; Anderson retrieved two space exposure experiments
while Williams adjusted an antenna gimbal lock assembly. After that, the spacewalkers worked
together to install a wireless instrumentation antenna on the Destiny laboratory module. Deferred to
a future spacewalk was work to tie down debris shields on Destiny and the multi-hatch Unity
connecting module.
As they worked to install the wireless antenna, the space station sailed 214 miles above Hurricane
Dean.
"Oh, wow!" one of the astronauts - presumably Williams - exclaimed as he caught sight of the huge
storm. "Oooo man, can't miss that!""Holy smoke," Anderson said. Television views from the station
showed the hurricane in its entirety, sporting a tight, well-defined eye at the heart of of the storm.
"That's impressive," Williams said.
"Can you see the eye?"
"Oh yeah," Williams said. "Definitely."
"Oh yeah, that's wild," Anderson said. "All right, Dave, I'm going to put another tether on there
before I hand it to you."
"Copy that," Williams said as the two spacewalkers continued work to install a wireless
instrumentation antenna. "Man, that's impressive."
"Very," Anderson agreed, adding: "They're only impressive when they're not coming to you."

"That's true."
The spacewalk began at 9:17 a.m. and ended at 2:19 p.m. for a duration of five hours and two
minutes. Williams, Anderson and shuttle astronaut Rick Mastracchio logged a total of 23 hours and
15 minutes of spacewalk time across four outings during Endeavour's mission. This was the 92nd
spacewalk since station construction began in 1998 and the 15th so far this year. Total station
assembly EVA time now stands at 567 hours and 59 minutes.
2:25 PM, 8/18/07, Update: Astronauts marvel at Hurricane Dean; wrap up abbreviated spacewalk
Canadian astronaut Dave Williams and space station flight engineer Clay Anderson staged an
abbreviated fourth and final spacewalk today, pausing for a moment to take in a spectacular bird's
eye view of Hurricane Dean, the storm that prompted NASA managers to make preparations for an
earlier-than-planned undocking and landing.
The spacewalk began at 9:17 a.m. and ended at 2:19 p.m. for a duration of five hours and two
minutes. Williams, Anderson and shuttle astronaut Rick Mastracchio logged a total of 23 hours and
15 minutes of spacewalk time across four outings during Endeavour's mission. This was the 92nd
spacewalk since station construction began in 1998 and the 15th so far this year. Total station
assembly EVA time now stands at 567 hours and 59 minutes.
Concerned about the possibility of an evacuation that could force NASA to move mission control
from Houston to more limited facilities at the Kennedy Space Center in Florida, NASA managers told
the astronauts to shave two hours off today's spacewalk as part of a plan to preserve the option of
undocking early Sunday and landing Tuesday, a day ahead of schedule.
By shortening today's spacewalk, the astronauts can make final equipment transfers and close the
hatches between Endeavour and the space station around 5 p.m., setting the stage for undocking
Sunday. NASA's Mission Management Team planned to review the forecast during an afternoon
meeting and make a decision about how to proceed after hatch closure.
Williams and Anderson accomplished three primary objectives during today's spacewalk. They
installed clamps on the station's main solar array truss that will be used next year to temporarily
hold a shuttle heat shield inspection boom; Anderson retrieved two space exposure experiments
while Williams adjusted an antenna gimbal lock assembly. After that, the spacewalkers worked
together to install a wireless instrumentation antenna on the Destiny laboratory module. Deferred to
a future spacewalk was work to tie down debris shields on Destiny and the multi-hatch Unity
connecting module.
As they worked to install the wireless antenna, the space station sailed 214 miles above Hurricane
Dean.
"Oh, wow!" one of the astronauts - presumably Williams - exclaimed as he caught sight of the huge
storm. "Oooo man, can't miss that!""Holy smoke," Anderson said. Television views from the station
showed the hurricane in its entirety, sporting a tight, well-defined eye at the heart of of the storm.
"That's impressive," Williams said.
"Can you see the eye?"
"Oh yeah," Williams said. "Definitely."

"Oh yeah, that's wild," Anderson said. "All right, Dave, I'm going to put another tether on there
before I hand it to you."
"Copy that," Williams said as the two spacewalkers continued work to install a wireless
instrumentation antenna. "Man, that's impressive."
"Very," Anderson agreed, adding: "They're only impressive when they're not coming to you."
"That's true."
Williams, Mastracchio, Endeavour commander Scott Kelly, pilot Charles Hobaugh, Tracy Caldwell,
Al Drew and educator-astronaut Barbara Morgan plan to say goodbye to their space station
colleagues - Expedition 15 commander Fyodor Yurchikhin, Oleg Kotov and Anderson - during a brief
farewell ceremony in the Destiny laboratory module around 4:46 p.m. Hatches between the two
spacecraft are expected to be closed about 15 minutes later. Today's mission status briefing is
scheduled to begin at roughly the same time and this status report will be updated as soon as
possible thereafter.
9:18 AM, 8/18/07, Update: Spacewalk begins
Floating in the space station's Quest airlock module, Canadian astronaut Dave Williams and flight
engineer Clay Anderson switched their spacesuits to internal battery power at 9:17 a.m. to officially
kick off an abbreviated four-and-a-half-hour spacewalk, the fourth and final excursion planned for
the shuttle Endeavour's mission. The spacewalk began about 45 minutes ahead of schedule.
The first item on the agenda today is installation of clamps on the station's main solar array truss
that will be used next year to temporarily hold a shuttle heat shield inspection boom. Anderson then
plans to retrieve two space exposure experiments while Williams adjusts an antenna gimbal lock
assembly. After that, the spacewalkers will work together to install a wireless instrumentation
antenna, the last planned task for today's EVA.
6:58 AM, 8/18/07, Update: Crew gears up for hurricane-shortened spacewalk, early hatch closure
Canadian astronaut Dave Williams and space station flight engineer Clay Anderson are preparing for
a shortened spacewalk today while their crewmates complete final equipment transfers to and from
the station to clear the way for hatch closure later this afternoon. Concerned about the threat of
Hurricane Dean, NASA managers have ordered the early hatch closure to protect the option of
undocking Sunday and landing Tuesday, a day ahead of schedule, to get the shuttle back on the
ground before mission control in Houston might have to be evacuated.
"Good Morning Endeavour! Thanks for the great day yesterday!" flight controllers said in a message
uplinked to the crew early today. "You are an awesome crew! We are looking forward to the EVA
today. As you were briefed last night, the EVA will be shortened so that hatch closure can take place
this evening. You will undock tomorrow morning. Landing is being planned for Tuesday. This is all
because of the potential threat to JSC posed by hurricane Dean. Thanks for your flexibility!"
Mission control commentator Rob Navias, however, said early today no final decisions have been
made to undock Sunday and depending on updates to Hurricane Dean's projected track, mission
managers presumably could change their minds. But barring a major change, the hatches will be
closed around 5 p.m. today.

Today's spacewalk will be the 92nd since station construction began in 1998, the 15th so far this
year and the fourth for Endeavour's mission. It will be the third for both Williams and Anderson.
Going into today's EVA, 72 men and women had logged 562 days and 57 minutes of spacewalk time
building and maintaining the international lab complex.
Items on today's agenda include installation of mounting brackets on the station's solar array truss
to temporarily hold a shuttle heat shield inspection boom next year; retrieval of two space exposure
experiment packages; get-ahead preparation of antenna gimbal locks; and installation of a wireless
instrumentation antenna.
Anderson and Williams originally planned to carry out a six-and-a-half-hour spacewalk, but the
revised flight plan shaved two hours off the excursion. Tasks that will be deferred to a future shuttle
flight or to a station crew include work to tie down debris shields on the Destiny and Unity modules
and a few other low-priority get-ahead tasks.
Here is the replanned timeline for today's activity (in EDT and mission elapsed time):
EDT........DD...HH...MM...EVENT08/18/0705:07 AM...09...10...30...STS/ISS crew wakeup05:47
AM...09...11...10...EVA-4: Airlock repressurized to 14.7 psi06:07 AM...09...11...30...EVA-4: Hygiene
break06:27 AM...09...11...50...EVA-4: Airlock depressurized to 10.2 psi06:57 AM...09...12...20...EVA-
4: Campout EVA preparations08:27 AM...09...13...50...EVA-4: Spacesuit purge08:42
AM...09...14...05...EVA-4: Spacesuit pre-breathe08:57 AM...09...14...20...Logistics transfers
resume09:32 AM...09...14...55...EVA-4: Airlock depressurization10:07 AM...09...15...30...EVA-4:
Airlock egress and setup10:22 AM...09...15...45...EVA-4: Orbiter inspection boom S1 mounting
brackets installed11:07 AM...09...16...30...Oxygen system tear-down11:22 AM...09...16...45...EVA-4:
EV3: S-band antenna sub-assembly gimbal locks11:22 AM...09...16...45...EVA-4: EV3: MISSE space
exposure experiment retrieval12:07 PM...09...17...30...EVA-4: Wireless instrumentation system
antenna installation01:47 PM...09...19...10...EVA-4: Payload bay cleanup02:12
PM...09...19...35...EVA-4: Airlock ingress02:32 PM...09...19...55...EVA-4: Airlock
repressurization02:47 PM...09...20...10...Post-EVA spacesuit servicing03:02
PM...09...20...25...MISSE disassembly03:22 PM...09...20...45...MISSE transfer to shuttle03:47
PM...09...21...10...Spacesuit transfer to shuttle03:57 PM...09...21...20...Transfer tagup04:47
PM...09...22...10...Farewell ceremony05:02 PM...09...22...25...Hatches closed05:27
PM...09...22...50...Rendezvous tools checkout05:27 PM...09...22...50...Leak checks08:07
PM...10...01...30...ISS crew sleep begins08:37 PM...10...02...00...STS crew sleep beginsNASA's
Mission Management Team will meet later today to evaluate Dean's progress and make a decision
on when to undock. If the decision is to press ahead for a Tuesday landing, undocking would be
targeted for 7:57 a.m. Sunday, setting up a landing back at the Kennedy Space Center around 12:29
p.m. Tuesday.
The astronauts originally planned to carry out a full-duration spacewalk today and finish up
equipment and supply transfers to and from the lab complex Sunday. Hatches between Endeavour
and the station were scheduled to be closed Sunday night to set the stage for undocking Monday. A
now-routine post-Columbia final heat shield inspection was on tap Monday afternoon and the crew
planned to pack up and test the shuttle's re-entry systems Tuesday. Touchdown at the Kennedy
Space Center was targeted for around 12:52 p.m. Wednesday.
But Hurricane Dean has thrown a wrench into those plans because NASA may be forced to evacuate
the Johnson Space Center early next week. If so, and if landing remained targeted for Wednesday,
the agency would have to set up an emergency mission control center at the Kennedy Space Center.
While controlling a shuttle from Kennedy is part of a long-established contingency plan, NASA would

have to rely on a much smaller team and give up some of its ability to monitor the orbiter's myriad
systems. By moving landing up a day, NASA likely could ensure a normal JSC-controlled re-entry.
But to land Tuesday, the Endeavour astronauts will have to finish equipment transfers today, during
and immediately after the spacewalk, and close hatches between the two spacecraft this evening.
The crew then could undock Sunday and have the normal two days to carry out a final heat shield
inspection, test the ship's re-entry systems and pack up for landing.
"After the crew went to sleep, we spent a lot of time replanning Saturday and Sunday's timelines,"
said overnight flight director Heather Rarick. "To land on Tuesday, that means we'd have to undock
on Sunday, which means we'd have to close the hatch on Saturday night. So we developed a plan for
that. Most of the morning stays the same for that timeline. We will go out and do the EVA, we are
going to shorten it if we need to so that we can get the crew back inside and be able to transfer the
spacesuits and tools back to the shuttle and then close the hatch in the evening."
Endeavour carried some 5,000 pounds of equipment and supplies for the station. Another 4,000
pounds of hardware and no-longer-needed equipment were to be brought back to Earth on the
shuttle. Rarick said the crew was ahead of schedule on transfer activity and most of the resupply
work will be finished before hatch closure.
"There are a couple of things that we need to do late, so we've been holding off on them
intentionally," she said. "One of the items is a cycle ergometer (exercise bike), we've brought a new
one onto space station to replace the current one. But before we can send the old one home, we
need to install it and check it out. So we have that on the timeline early (today)."
During today's spacewalk, Anderson plans to retrieve two space exposure experiment packages that
will be moved into the shuttle for return to Earth.
"Other items we need to pack late is we have some experiments in the space freezer on space station
and we need to put those in cooler bags so they can be brought home and kept at the proper
temperature and we want to do that as late as possible in the flight," Rarick said. "So we have that
timelined for late in the afternoon, just before the hatch gets closed."
In the crew's daily execute package of notes and flight plan changes uplinked from mission control,
NASA's Mission Management Team gave the crew a big-picture overview of hurricane preparations.
"Hurricane Dean Preparations: The MMT received a briefing on the latest Hurricane Dean National
Hurricane Center forecast track from the Spaceflight Meteorology Group. The projected track places
the eye of a Category 4 storm in the Gulf of Mexico on Wednesday, FD15. Uncertainties in the
forecast may change this prediction by +/- 6 hours. A low pressure system is forecasted to track
west across the Gulf of Mexico from Florida to Louisiana. This low pressure system may influence
the hurricane to take a more northerly ground track. Additionally, a more northerly track could lead
to additional strengthening since the storm could miss the Yucatan peninsula entirely.
"JSC Senior Management will be meeting daily to assess the hurricane and will be making decisions
appropriately. If the track of the hurricane holds to the forecast, it is expected that JSC will be
closed on Monday, FD13, allowing non-mission support personnel to care for their families. All
disciplines reporting to the MMT are preparing a list of mandatory support personnel that could
support the remainder of the mission from JSC. The flight control team is making preparations to
staff accordingly to support mission operations through landing."

8:44 PM, 8/17/07, Update: Kelly supports fly-as-is decision; NASA managers study hurricane options
(UPDATED at 8:07 p.m. with MMT decision to protect option of landing Tuesday; UPDATED at 8:46
p.m. with 'big picture' words to crew about possible Tuesday landing)
NASA's Mission Management Team, after resolving concerns about damage to the shuttle
Endeavour's heat shield, shifted gears today and began discussing the possibility of bringing the
astronauts back to Earth on Tuesday, a day early, because of concern Hurricane Dean could
threaten a shutdown of mission control at the Johnson Space Center in Houston.
"The current forecast for the storm would have the eye of Dean in the center of the Gulf area
sometime on Wednesday," said LeRoy Cain, co-chairman of NASA's Mission Management Team. "If
you back up from there to look at evacuation plans, not only for Johnson Space Center but for
surrounding areas here, our history from previous hurricanes and storms tells us we really have to
start letting our personnel go and take care of themselves and their families in the Sunday kind of
time frame, if not sooner.
"And so, we began to look at this and determined we would really like to protect an option to be able
to end the mission on Tuesday," he said. "From an institutional standpoint, the center will have to
make a decision sometime in the mid-Sunday to mid-Monday time frame as to whether or not to
close the center, and if so, when will they close? For a storm that's headed for the Houston area, in
all likelihood the center would look at closing sometime on the second half of Monday-to-certain-
y-by-Tuesday timeframe. ... So we factored all that in and determined we would really like to protect
an option to land on Tuesday."
The Endeavour astronauts plan to carry out a fourth and final space station assembly spacewalk
Saturday and finish up equipment and supply transfers to and from the lab complex Sunday. Hatches
between Endeavour and the station are scheduled to be closed Sunday night to set the stage for
undocking Monday. A now-routine post-Columbia final heat shield inspection will be carried out
Monday afternoon and the crew will pack up and test the shuttle's re-entry systems Tuesday.
Touchdown at the Kennedy Space Center is targeted for around 12:52 p.m. Wednesday.
But plans are being put in place to close hatches between Endeavour and the space station Saturday
night to permit an undocking Sunday and landing Tuesday depending on Dean's eventual track.
Astronaut Shane Kimbrough called the crew from mission control late Friday to explain the
discussion.
"Endeavour and station on the big loop with big picture words," he radioed from Houston. "Due to
Hurricane Dean and its potential impact to the Gulf Coast, we're working towards a plan that would
land us a day early. The way we're going to get there is to give up some transfer activities tomorrow
and possibly shorten EVA-4. That will allow us to close the hatches tomorrow night and then we'll
undock on Sunday and land on Tuesday. We're working the timeline really hard down here as you
might imagine, we'll have a detailed plan for you in the morning."
Mission control commentator Kyle Herring said no final decisions about landing Tuesday had been
made, but there are "a number of items that protect for that option and those were relayed up to the
crew, which basically focuses on the duration of the ... spacewalk tomorrow by Dave Williams and
Clay Anderson."
The problem for NASA is the pace of Hurricane Dean, the time needed to complete normal mission
work and when decisions would have to be made in advance of Dean's arrival in the Gulf of Mexico.
The concern, in part, is the risk associated with controlling a flight from a backup mission control

center in Florida with fewer engineers, and less computer processing power, to monitor the shuttle's
myriad systems.
"There are two parts to the emergency mission control center activation," said shuttle flight director
Matt Abbott. "One is you take a team of controllers and send them to KSC and have them set up and
be there on standby and ready to take over if that becomes necessary. So that can be done as a
precaution, just like we can do the same thing with the backup control center advisory team
activities on the station side.
"But ... we have a lot more limited insight into the vehicle systems, or at least less people to monitor
that insight into the vehicle systems. We do have the capability to keep things going and to get the
vehicle on the ground safely, but again, when you look at the effort and the number of people we
have involved in a mission and a landing here and then you skinny that down to a couple of dozen
people, there is obviously an element of additional risk because you're not able to do all the things
you used to be able to do here in Houston. So that's really it in a nutshell."
While controlling a shuttle from Kennedy is part of a long-established contingency plan, "the systems
and facilities down there are set up to get vehicles launched and off the pad and the activities we do
here (in Houston) are a little bit different," Abbott said. By moving landing up a day, NASA likely
could ensure a normal JSC-controlled re-entry.
But to land Tuesday, if it came to that, the Endeavour astronauts would have to finish equipment
transfers Saturday, during and immediately after the spacewalk, and close hatches between the two
spacecraft Saturday night. The crew then could undock Sunday and have the normal two days to
carry out a final heat shield inspection, test the ship's re-entry systems and pack up for landing.
Cain said senior managers planned to meet late Friday to prioritize the activities planned for
Saturday's spacewalk. Because most of the work is made up of relatively low-priority "get-ahead"
tasks that could be deferred with no major impact on station assembly, mission managers may opt to
shorten the spacewalk to make it easier for the crew to complete the tasks required before the
hatches would be closed.
At the same time, NASA managers are putting lists of key personnel together and determining what
would be necessary to activate all three shuttle landing sites - the Kennedy Space Center, Edwards
Air Force Base, Calif., and White Sands Space Harbor, N.M. - on Tuesday.
Space station controllers also are reviewing contingency plans for moving key flight personnel to a
backup site in Texas. If Hurricane Dean shuts down the Johnson Space Center, the flight control
team could route commands through Russian ground stations as required.
"It's really too early to say exactly how this is all going to play out," said Abbott. "We've got options
that we're looking at, we're trying to lay all those out so we know exactly what our capabilities are
and what we have available to us."
For the record, the shuttle has enough on-board supplies to remain in orbit until next Friday with
two days beyond that held in reserve as always to handle major systems problems or bad weather.
Earlier today, the astronauts held their traditional in-flight news conference and shuttle commander
Scott Kelly fielded a variety of questions about the health of the shuttle's heat shield and his comfort
level with a management decision to forego a spacewalk repair job.

"We agree absolutely 100 percent with the decision to not repair the damage," Kelly said during an
in-flight news conference. "There was a lot of engineering rigor put into making this decision, it took
some time but that was because there was a lot of testing going on, arc jet testing in particular that
took some time to get done. ... With the damage that we have, the maximum temperature (the
shuttle's aluminum skin) will see is 340 degrees. The failing point of aluminum, I think, is
somewhere over 1,000 degrees. So even though a repair could potentially provide a little bit more
margin, there is certainly more risk in doing the repair than we're willing to take. We were certainly
concerned that if we did the repair we could potentially cause more damage to the underside of the
orbiter. Since a repair was not really warranted based on the data and the testing, the shuttle crew
and the station crew, actually, agreed with the decision not to do the repair."
He said work to resolve the issue "was a very, very rigorous process" and "I for one am happy it took
as long as it did."
"They delayed our fourth EVA a day to give themselves more time so they wouldn't be pressed by the
schedule," he said. "If it had turned out the MMT decided we needed to do a repair, we could have
done it tomorrow. ... So I think it was absolutely the right decision to forego the repair and I think
they took the appropriate amount of time to come to that conclusion. I would have been a little bit
more nervous if they had just looked at the data we provided in the focused inspection (last Sunday)
and say you know, either we had to repair it or we didn't. This is a very complicated process and it
takes time to complete. We are absolutely behind the MMT, we think they made absolutely the right
decision."
Asked if he thought entry might be a bit more tense for the crew because of known damage to the
heat shield, Kelly said "I personally do not. We've had shuttles land with worse damage than this. We
gave this a very thorough look and I am very, very comfortable and there will be no extra concern in
my mind due to this damage."
Added pilot Charles Hobaugh: "I totally agree with Scott. I don't think there's anything really to
concern us. John Young (commander of the first shuttle mission) used to always sit in our Monday
morning meetings and talk about all the tiles that fell off of STS-1 and how they made it back fine.
So I don't think it's really an issue and I think it was a great decision."
10:24 AM, 8/17/07, Update: Crew prepares for Saturday spacewalk; continues supply transfer work
The Endeavour astronauts are working through a busy day in space today, trying to trace a subtle
communications wiring problem, transferring supplies and equipment to and from the international
space station and preparing for a fourth and final spacewalk Saturday. The astronauts plan to
participate in a traditional in-flight news conference at 1:34 p.m. Today's mission status briefing is
scheduled for 3 p.m.
Here is an updated timeline of today's activities, based on the crew's flight plan and revision N of the
NASA television schedule (in EDT and mission elapsed time):
EDT........DD...HH...MM...EVENT05:07 AM...08...10...30...STS/ISS crew wakeup08:12
AM...08...13...35...EVA-4 tool preparation08:27 AM...08...13...50...Logistics transfers resume11:02
AM...08...16...25...DAIU communications troubleshooting01:12 PM...08...18...35...Crew photo01:34
PM...08...18...58...Joint crew news conference02:12 PM...08...19...35...Joint crew meal03:00
PM...08...20...24...Mission status briefing on NASA TV03:12 PM...08...20...35...Logistics transfers
resume03:12 PM...08...20...35...Spacehab debris shields checked03:32 PM...08...20...55...DAIU
wrapup04:07 PM...08...21...30...Spacesuit swap04:37 PM...08...22...00...Equipment airlock

prepared05:22 PM...08...22...45...Logistics transfer tagup05:37 PM...08...23...00...EVA-4: Procedures
review07:32 PM...09...00...55...EVA-4: Nitrogen purge mask pre-breathe and tool config08:17
PM...09...01...40...EVA-4: 10.2 psi airlock depressurization08:37 PM...09...02...00...ISS crew sleep
begins09:07 PM...09...02...30...STS crew sleep beginsSaturday's spacewalk by Canadian astronaut
Dave Williams and station crew member Clay Anderson is devoted to a variety of get-ahead tasks
that will help pave the way for future space station assembly missions. The excursion originally was
planned for today, but it was delayed 24 hours to give flight controllers time to assess whether a
heat shield repair job was needed to fill in two damaged tiles on the belly of the shuttle.
Late Thursday, mission managers decided test data and analysis proved Endeavour could safely
return to Earth as is. A tile repair spacewalk was ruled out and the astronauts were told to press
ahead with the station assembly EVA instead.
The damage assessment brought back memories of an internal debate after the shuttle Columbia's
launching in 2003. In that case, a relatively limited study was carried out to determine the possible
damage caused by a large piece of foam debris that hit the underside of the shuttle's left wing
during launch. NASA's Mission Management Team accepted a hurried analysis by a small group of
engineers and concluded Columbia could safely re-enter as is even though the actual impact site
could not be seen in launch imagery.
The analysis was deeply flawed. Equally troubling in hindsight, the Mission Management Team did
not hear, or take seriously, concerns from lower-level engineers who were not satisfied with the
review. As it turned out, what NASA managers believed was relatively minor damage to heat-shield
tiles was, in fact, a 4- to 6-inch hole in the leading edge of Columbia's left wing. Sixteen minutes
from touchdown, the left wing failed, the spacecraft broke apart and all seven crew members were
killed.
Memories of Columbia still linger and the MMT decision not to mount a repair spacewalk to fix the
damage to Endeavour's heat shield made some outside observers uncomfortable. But Shannon said
he was "100 percent" confident the team made the right decision.
Unlike the Columbia case, NASA now has the ability to photograph virtually every square inch of the
shuttle's heat shield, high-resolution cameras to zoom in on damage sites and an on-board laser
scanner to measure its extent in three dimensions. Sophisticated computer modeling software has
been developed to help engineers accurately predict the effects of re-entry heating. And NASA has
tried to set up a management system that encourages debate, peer review and minority reports.
All of those systems were in play during the analysis of Endeavour's heat shield, Shannon said.
Mockups of the damage site were subjected to re-entry heating in a high-tech furnace at the Johnson
Space Center. Computational fluid dynamics was brought to bear to model heating and its effects
under a variety of conditions and that work was peer reviewed to ensure accuracy. When all was
said and done, engineers unanimously concluded the damage did not pose any sort of catastrophic
threat to the crew and all but one engineering organization voted to clear Endeavour for entry as is.
The lone dissenting vote was cast by an engineering group at the Johnson Space Center that
believed a repair might add a bit of additional margin.
"If we had a condition that I thought was a threat to crew safety I would go execute this EVA and
feel pretty good about it," Shannon said. "Since that is not the case, since we had independent
analyses to show this is not expected to be even a turn-around issue to the vehicle, there's no way I
could justify sending the crew out on that EVA just because, just to go do something. And so it
became, I think, a very simple decision once we got that analysis done."

The rigor of that analysis and the widespread multi-center approach to studying - and verifying -
results, Shannon said, reflects a "night and day" difference between the way NASA approaches in-
flight problems today versus four years ago. That doesn't mean mistakes can't be made. But
Shannon clearly believes NASA has the safeguards in place to minimize the likelihood of a fatal
error.
"Because we have expended the resources and spent the time to develop the tools, not just the
hardware tools but the analytical tools, to be able to understand exactly what the condition of the
thermal protection system is," he said. "You saw on this flight several things, one is all of the new
capabilities that we have added since Columbia, from the ground cameras to the in-flight cameras to
the in-flight radar system that's looking specifically for debris, we used every one of those. From the
rendezvous pitch maneuver we do close to the station, we got that data. We did the leading edge
scans with the (heat shield inspection) boom. And then we had the discussions on the analytical tool
capability, our ability to analyze this high energy environment. And we have repair capabilities.
"The more important thing to me is the seriousness and thoroughness with which the entire
community analyzed this particular case," Shannon said. "This is not different from the (displaced)
OMS pod (insulation) blanket we had on the last flight. We do not clear anything until we have the
data to clear it and we take things extremely seriously and we bring to bear the resources of the
entire agency, even expertise outside of the agency when we can bring it in. We had computational
fluid dynamics at Ames (Research Center). It was backed up at Langley Research Center. We have
had expertise at Johnson, at Kennedy at Marshall (space centers), at all the NASA centers.
"It's a little bit of a double edged sword, right? Because I would have liked to come in early on and
say guys, let's not blow this out of proportion, it doesn't look like a loss-of-crew-and-vehicle kind of
case, let's not get too excited about this. But we really can't do that because we didn't know at that
point.
"You have to go do the analysis to know," he said. "And I think that is the key, as I am 100 percent
comfortable that the work that has been done has accurately characterized it and we will have a
very successful re-entry. I am also 100 percent confident that if we had gotten a different answer
and found out that this was something that was going to endanger the lives of the crew that we have
the capability on board to go and repair it and then have a successful entry. So we're setting
ourselves up really well both ways."
11:21 PM, 8/16/07, Update: Shannon says tests show Endeavour can safely land as is; repair
spacewalk ruled out; decision virtually unanimous; dissent centered on possibility of post-landing
repairs, not crew safety
NASA's Mission Management Team today ruled out an unprecedented heat shield repair spacewalk
and cleared the shuttle Endeavour for re-entry and landing next week "as is" based on computer
modeling and tests in a high-temperature furnace that show a small gouge in the ship's belly will not
cause serious damage during the fiery plunge to Earth.
Assuming concern about a small tear in a spacesuit glove can be resolved, the MMT cleared the
astronauts to press ahead instead with a fourth and final space station assembly spacewalk Saturday
that will focus on a variety of relatively low-priority "get ahead" tasks to help pave the way for
upcoming missions. If all goes well, Endeavour will undock from the station Monday and glide to a
landing at the Kennedy Space Center in Florida around 12:52 p.m. Wednesday to close out an
extended two-week mission.

"The MMT made two significant decisions tonight," Shannon said. "The first was a unanimous
recommendation that the damage we saw after reviewing all the engineering tests and analysis was
not a threat to crew safety, this was not something that the astronauts are in danger about. We had
thought that for several days, but we were waiting for the final analysis to be complete.
"We did all the things that we said we were going to do over the last few days. We had engineering
analyses, we had computational fluid dynamics of the cavity from both Ames Research Center and
the Langley Research Center, they were both in agreement. We did the thermal analysis and that
continued to show good margins and we also did two arc jet tests where we put a re-entry heating
profile on the damage sites.
"We went through all of that data and it was unanimous that we were not in a loss of crew/vehicle
case," Shannon said. "The discussion then centered on whether we should use as is and return
Endeavour in its current condition or if the uncertainties in the analysis could potentially cause some
underlying tile damage or structural damage that we would have to deal with at the Kennedy Space
Center. So we had that debate. And it was not unanimous, but it was pretty overwhelming to go with
the use-as-is condition, in other words not to do the tile repair."
Commander Scott Kelly, pilot Charles Hobaugh, Tracy Caldwell, flight engineer Rick Mastracchio,
Canadian flier Dafydd Williams, Al Drew and educator-astronaut Barbara Morgan were informed of
the decision at 9 p.m. as they were preparing for sleep.
"Just wanted to pass along the MMT just broke out of their meeting," astronaut Shane Kimbrough
radioed from mission control. "The MMT has made a decision to fly the TPS (thermal protection
system) as is, no EVA repairs will be required. MMT is still looking at the cut glove issue and any
future EVAs on the flight will be per the nominal content. So just wanted to wish you a good night,
another great day in space and looking forward to tomorrow."
"Please pass along our thanks for all the hard work," Kelly replied.
Two heat-shield tiles on the shuttle's belly were damaged when a chunk of foam debris, possibly
including ice, slammed into the orbiter 58 seconds after launch last Wednesday. The impact gouged
out an irregular pit crossing the boundary between two tiles, measuring roughly two inches by three
inches across and nearly penetrating the full 1.12-inch thickness of the tile. A small, 1-inch by 0.2-
inch gash at the bottom of the pit exposed an underlying support pad just above the shuttle's
aluminum skin.
The shuttle Columbia was destroyed Feb. 1, 2003, when it re-entered the atmosphere with a gaping
4- to 6-inch hole in the leading edge of its left wing. The wing melted from the inside out, the shuttle
broke apart above Texas and all seven crew members were killed. NASA managers have said all
week that they do not view Endeavour's gouge as a Columbia-class problem. Shannon said the issue
was simply whether re-entry heating might cause damage to the shuttle's aluminum skin in the
immediate area that would require time-consuming post-landing repairs.
Testing and computer models predict the underlying aluminum skin of the shuttle's right wing will
never get hotter than 350 degrees Fahrenheit, NASA's safety limit. At worst, Shannon said, a few
downstream tiles could be damaged, along with the two that were gouged out by the impact during
launch.
Playing it safe, Shannon earlier asked a team of astronauts, engineers, flight controllers and
managers to study repair options to determine the best approach if the heat shield had to be fixed.

To protect their options, a station assembly spacewalk planned for Friday - what was to have been
the crew's fourth and final EVA - was delayed 24 hours to Saturday.
But Shannon said late Thursday that a final round of tests agreed with computational fluid dynamics
modeling and an independent review of the work turned up no major surprises. The MMT then voted
and cleared Endeavour's crew for a standard station assembly spacewalk Saturday and an "as is"
landing next week.
But the vote was not unanimous. While representatives of more than 30 organizations voted to
proceed with landing as is, Johnson Space Center engineering argued it would be "prudent" to carry
out a repair even though the data indicated Endeavour could safely return in its damaged state.
"It was almost unanimous to use as is," Shannon said. "The one dissenting organization was the
Johnson Space Center engineering group, who took a look at the potential benefits of doing a repair
and said that they could not see a reason why that would cause additional damage to the orbiter and
thought that that was something we should think about as a program."
But Shannon said sister organizations at the Marshall Space Flight Center and the Kennedy Space
Center, along with the astronaut office at Johnson "all of the safety organizations I have on my
panels, they were all in agreement that the use-as-is was the appropriate way to go."
"Some of the rationale that was summed up by the team members that I think was fairly consistent
across the management team was that we have a cavity in the tile that has been analyzed through
computational fluid dynamics, through thermal analysis, through two different arc jet tests and we
understand that cavity, it does not constitute a risk to the crew, it is not expected to cause any
damage to the vehicle structure itself and it is fairly well understood.
"On the other hand, we could potentially do this spacewalk and add some (STA-54 repair) material to
the bottom of this cavity ... then we would have a new cavity that we had not analyzed. That was a
fairly simple decision, is you have something you know you can live with, why would you take the
risk of doing the EVA to change that cavity into what could potentially be an even better situation
but also could potentially be a worse situation?"
The MMT decision ended a week of high drama on the high frontier, with engineers working around
the clock to assess the threat posed by the dinged tiles and, in parallel, develop repair plans in case
they were needed. The astronauts received frequent updates as they pressed through a busy
timeline that included three spacewalks to attach a solar array truss segment; replace a stabilizing
gyroscope; and prepare a solar array for relocation later this year.
During the third spacewalk Wednesday, Mastracchio noticed a small tear in the Vectran material
used in his left glove and flight controllers ordered him back to the space station's airlock as a
precaution. This was the second spacewalk in three shuttle missions that has resulted in glove
damage and engineers suspect something on the station has an unexpected sharp edge.
Before Saturday's spacewalk can proceed, spacewalk experts at the Johnson Space Center hope to
confirm the problem with Mastracchio's glove was not part of a more generic problem that could
affect Williams or Anderson. They also are reviewing helmet cam video from Mastracchio in a bid to
identify what might have caused the damage.
Here is a revised timeline for Saturday's spacewalk (in EDT and elapsed time):

EDT........HH...MM...EVENT10:06 AM...00...00...Airlock egress10:26 AM...00...20...Orbiter boom
sensor system (OBSS) boom stand installation11:26 AM...01...20...Williams: Z1 S-band antenna sub-
assembly gimbal locks11:26 AM...01...20...Anderson: MISSE space exposure experiment package
retrieval12:11 PM...02...05...Wireless instrumentation antenna installation01:51
PM...03...45...Destiny module debris shield cleanup02:06 PM...04...00...Unity module debris shield
cleanup03:21 PM...05...15...Other get ahead tasks03:51 PM...05...45...Cleanup04:21
PM...06...15...Airlock ingress04:36 PM...06...30...Airlock repressurizationOn Wednesday, Shannon
made it clear he viewed a heat shield repair spacewalk as risky and said that such a repair could
only be justified if it was necessary to prevent serious damage during re-entry.
The repair plan called for a 50-foot-long extension called the orbiter boom sensor system, or OBSS,
to be attached to the end of the shuttle's 50-foot-long robot arm. Mastracchio planned to ride on the
end of the boom, his feet anchored in a work platform, while Williams provided assistance as a free
floater, tethered to the boom.
Working from Endeavour's aft flight deck, Caldwell was to have moved the astronauts down under
the shuttle and back to the damage site, located a few feet aft of the right main landing gear door.
The repair planned called for Mastracchio first to dab a black paint-like material known as emittance
wash into the gouge, using a simple device that works like a liquid shoe polish applicator.
After the walls of the gouge were coated with emittance wash, he was to use a different type
applicator, one that works like a grease gun, to squeeze out and mix a thick, putty like material
known as STA-54. Like epoxy, STA-54 mixes as it exits the applicator and it can be difficult to work
with. But Mastracchio helped develop some of the necessary procedures and engineers were
confident he could successfully fill in a portion of the gouge.
But on Wednesday, Shannon pointed out three areas of concern about the repair spacewalk, saying
"none of these are real show stoppers but you kind of have to add them up in your mind."
First, he said, working under the shuttle on the end of a 100-foot boom with poor television coverage
in proximity with a critical system has never been attempted before. "That was not a show stopper,
but it was something to think about," he said.
Second, astronauts have never applied STA-54 in the vacuum of space and third, no one knows if the
applicator will work properly or if the spacewalkers might have problems getting the thick material
into the gash. "It takes a little bit of practice to get it in exactly the right spot."
Late Thursday, Shannon said he would not hesitate to order a spacewalk repair if the data showed
repairs were needed to ensure a safe landing. In this case, he said, they simply didn't.
"We believe we're going to have to go replace a couple of tiles that got damaged," he said. "And that
is within the normal turnaround flow of a vehicle."
Asked if there was zero chance of a catastrophic loss of vehicle and crew due to the heat shield
gouge, Shannon said simply: "Yes."
9:00 PM, 8/16/07, Update: ADVISORY - Mission Management Team adjourns; tile repair spacewalk
ruled out; Endeavour cleared for entry 'as is'
After a five-hour meeting to assess the health of the shuttle Endeavour's heat shield, NASA's Mission
Management Team has ruled out a heat shield repair spacewalk Saturday and cleared the crew for

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