Space & Astronomy/Space and Astronomy (October 1993).iso/pc/text/shuttle/crewsaf.txt

Text File | 1993-02-04 | 25KB | 520 lines

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CREW ESCAPE SYSTEM


     A telescoping pole has been chosen as the egress method for
the Space Shuttle's crew escape system, to be incorporated
into the orbiter Discovery prior to the STS-26 flight in August 1988.

     The selection of the telescoping pole, over an alternative
tractor rocket extraction system, was made at NASA Headquarters
by National Space Transportation System Director Arnold D.
Aldrich following a review of system design, test performance and
flight hardware status.

     "The NASA-contractor team has done a fantastic job in
providing both the tractor rocket and telescoping pole systems to
support the next Shuttle flight," Aldrich said.  "The telescoping
pole was selected as it has shown to be safer, simpler to
operate, lighter weight and easier to support than the tractor
rocket system, while meeting all escape system performance
requirements."

     Tests conducted in February and March 1988, using a fixed pole
extending through a hatch-like opening in a C-141 aircraft,
demonstrated that the pole would provide adequate orbiter
clearance in an emergency egress situation.

     Navy parachutists, approximating the sizes of astronauts
from the smallest to the largest, completed a total of 66 jumps
using a lanyard attached to their parachute harness to slide down
the pole and descend to a safe landing.  Analysis of aerodynamic
and photographic data showed that all the jumps provided the
necessary clearance margins.

     The telescoping pole, designed and manufactured at NASA's
Johnson Space Center, Houston, is made of light-weight aluminum
and steel and weighs 241 pounds.  It is about 70 pounds lighter
than the tractor rockets system.  The rockets also have a 5-year
operational shelf life limitation and additional processing
requirements between flights.

     The pole housing attaches to the orbiter's middeck ceiling
and is 126.75 inches long.  The primary extension is 112.54
inches (arched length), and the end extension is 32.65 inches.

     For launch and landing, the unextended pole will be oriented
toward the closed crew hatch.   During on-orbit operations, the
pole will repositioned toward the middeck lockers and stowed on
the ceiling such that it will not interfere with the various
flight crew activities in the middeck area.

     This decision completes the crew escape system package.
Already approved and implemented are the orbiter primary crew
hatch jettison capability and crew support equipment -- a partial
pressure suit, oxygen equipment, a parachute, a life raft and
survival equipment for each crew member.

     The escape system provides crew escape capability from the
orbiter during controlled, gliding flight following failures or
difficulties during ascent or entry where landing at a suitable
landing field cannot be achieved.  Previous procedures for ascent
contingency aborts, where no landing site could be reached,
required orbiter ditching in the ocean, a condition which has
been shown by structural analysis to be extremely hazardous.

     The side hatch jettison system also can be highly beneficial
for certain ground contingencies following non-normal landings.
A crew escape slide, similar to those provided on commercial
airliners, has been implemented in conjunction with the
jettisonable hatch to support rapid post-landing contingency
egress.


CHANGES TO THE EMERGENCY EGRESS SYSTEM AT PAD 39-B

May 1988

     A number of modifications have been made to the emergency
egress system at Launch Pad 39-B to increase the margins of
personnel safety.

     Two baskets have been added to the 195-foot level of the
Launch Pad Fixed Service Structure.  Previously, there were five
baskets rated to hold four people weighing an average of 190
pounds.  Officials decided that the maximum individual weight
rating was not sufficient and increased it to 220 pounds per
person, which takes into account the weight of life-support
apparatus, such as air tanks, which escapees are likely to be
wearing.  Considering the bulk of the life-support apparatus,
officials also have decided that the baskets will be rated to
hold three people each instead of four, and will have a nominal
operating weight capacity of 660 pounds.  However, four people
will be permitted if necessary.  The maximum carrying capacity of
each basket is 880 pounds.

     The baskets were modified at KSC's Launch Equipment Shop.  A
side exit to the basket was incorporated, a flame-protective
covering was added over the existing webbed material and an
anti-roll-back brake was added to ensure the basket comes to rest
as quickly as possible.

     The braking mechanism for the baskets consists of a series
of increasing-density steel chains that drag through the sand in
the landing zone, decelerating the basket to a final stop.  The
new brake holds the baskets at their furthest extent of travel.
Before, the baskets would stop temporarily and then begin to move
backwards before coming to a complete stop.

     A rope arresting net at the end of the slidewire provides a
redundant stopping point for the basket in the unlikely event the
deceleration system fails.  At the stopping point, personnel exit
through the side opening.

     The basket will hang approximately 2-3 feet off the
ground.  The stainless steel sidewires will be restrained against
vertical movement to limit the variance in basket height as
occupants exit.

     Upon exiting, the crew members will make a decision as to
whether to enter armored personnel carriers and drive to safety,
or to enter an underground concrete bunker.  A new underground,
steel-reinforced concrete bunker was built and provides easier
access.  The bunker's roof is 1-foot thick and the walls are 15-
inches thick.  It is 20-feet long by 13.4-feet wide, and is
located just to the south of the slidewire basket termination
area.

     The bunker contains emergency air for breathing, an
emergency shower, a telephone and four fold-down bunks.  It
features a five-foot-wide roll-up door in addition to a standard
swing door.  The roll-up door will be open during the final
launch countdown for easier access in the bunker.

     Fire-protection plating was added to the Orbiter Access Arm
and on the 195-foot level of the Fixed Service Structure (FSS).
Previously, there was an open-grate floor, as used on the rest of
the pad levels.  It is from this level that the crew enters and
exits the Space Shuttle.

     Additional fire detectors have been installed on the FSS to
provide better coverage on the 195-foot level and the Orbiter.
The fire water spray system also has been upgraded for better
coverage on the egress paths.

     The lighting has been upgraded on the 195-foot level of the
FSS and at the slidewire landing area in the case of a night
emergency.  Emergency procedures and documents also have been
revised.

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SPACE SHUTTLE TRANSOCEANIC ABORT LANDING (TAL) SITES

   Planning for each Space Shuttle mission includes provi-
sions for an unscheduled landing at contingency landing
sites in the U.S. and overseas. Several unscheduled landing
scenarios are possible, ranging from adverse weather condi-
tions at the primary and secondary landing sites to mechani-
cal problems during the ascent and mission phases that would
require emergency return of the orbiter and its crew.

   The Transoceanic Abort Landing (TAL) is one mode of un-
scheduled landing. The orbiter would have to make an un-
scheduled landing if one or more of its three main engines
failed during ascent into orbit, or if a failure of a major
orbiter system, such as the cooling or cabin  pressurization
systems, precluded satisfactory continuation of the mission.

   The abort mode would depend on when in the ascent phase
an abort became necessary. The TAL abort mode was developed
to improve the options available if failure occurred after
the last opportunity  for a safe return to the launch site,
but before the first opportunity to fly once around the
Earth and return to a landing site. A TAL would be declared
between roughly T+2:30 minutes and Main Engine Cutoff
(MECO), about T+8 minutes, with the exact time depending on
the payload and mission profile.

   A TAL would be made at one of four designated sites,  two
in  Africa  and two in Spain: Ben Guerir Air Base,  Morocco;
Yundum International Airport, Banjul, The Gambia;  Moron Air
Base, Spain; and Zaragoza Air Base, Spain.

   Although  Banjul  has  many  of  the same features as the
three other TAL sites,  it is formally called  an  augmented
emergency landing site.

   Each  TAL  site  is  covered  by a separate international
agreement,  but all four are  considered  augmented  because
they have Shuttle-specific landing aids and NASA and Defense
Department personnel available during a launch.

   Space  Shuttles  are  launched eastward over the Atlantic
Ocean from KSC for insertion into equatorial  orbits.  In  a
TAL  abort,  the orbiter continues on a ballistic trajectory
across the Atlantic to land at a predetermined  runway.  The
four  sites NASA has designated for TALs have been chosen in
part because they are near the nominal ascent  ground  track
of the orbiter,  which would allow the most efficient use of
main engine propellant.

   Depending on mission requirements,  an orbiter follows an
orbital  insertion  inclination between 28.5 and 57 degrees,
with the lower inclination preferred in most  instances  be-
cause it allows for a higher maximum payload weight. High or
low inclination launches require different contingency land-
ing site.


BEN GUERIR AIR BASE, MOROCCO

   The primary TAL site for a low inclination launch is the
Ben Guerir Air Base in Morocco. Ben Guerir has also been
designated a weather alternate TAL site for high inclination
launches because of its geographic location and its landing
support facilities. Ben Guerir replaced a TAL site at Dakar,
Senegal, which NASA concluded was unsatisfactory due to run-
way deficiencies and geographic hazards.

   Morocco  is  located along the northwest coast of Africa,
between 27 degrees and 37 degrees north. It is shielded from
the desert of northern Africa by the Atlas mountains on  the
eastern  border  of  the country.  A cool ocean current runs
along the west coast,  similar to the situation in  southern
California,  which  makes  the  coastal areas subject to low
clouds and fog most of the year.  The interior  sections  of
the country are generally arid,  with most precipitation oc-
curring from October to April and concentrated in the north.

   Ben Guerir was designated as  a  TAL  site  in  September
1986.  Located on a flat, rocky, desert plain about 36 miles
north of Marrakech,  Ben Guerir is a  former  Strategic  Air
Command Base abandoned in 1963.  It has one runway, oriented
in a north-south direction, which is 14,000 by 200 feet with
a 720-foot overrun at the north end.  The runway surface has
been  rejuvenated,  and  an  operations and storage building
added.  NASA also  put  in  place  additional  fire-fighting
equipment,  personnel  transport  vehicles  and other ground
support equipment.  Communications include three  communica-
tion satellite circuits.

YUNDUM AIRPORT, BANJUL, THE GAMBIA

   Yundum Airport has been named an alternate to Ben Guerir
and Moron Air Base. Because of its in-plane location, Yundum
could also be used for a late TAL and to accomplish a TAL in
the event of in-flight failure of a second engine.

   Yundum was named a TAL site in September 1987. Yundum is
The Gambia's international airport, located adjacent to the
country's capital, Banjul. The airport is located on a flat
plain seven miles inland from the Atlantic and six miles
south of the Gambia River. The Gambia has a dry season which
extends from November to May, during which weather condi-
tions are generally good, the only difficulty being lowered
runway visibility due to dust.

   The airport lies almost directly below the 28.5-degree
flight path, hence its designation as an in-plane contin-
gency site. The runway is 11,810 feet by 150 feet wide, with
200- and 400-foot overruns, and 25-foot paved shoulders.
Three communications satellite circuits are used for com-
munication, along with two commercial Gambian telephone cir-
cuits.


MORON AIR BASE, SPAIN

   The Moron Air Base has been designated a weather alter-
nate TAL to the primary TAL, Ben Guerir, for low inclination
launches. Moron was designated a TAL site in 1984. Moron can
also serve as the secondary site for high inclination
launches. It is located about 35 miles southeast of Sevilla
and 75 miles northeast of Rota Naval Station. Although Moron
is close to the foothills of the Sierra de Ronda mountain
chain, most of the surrounding countryside is flat with a
few hills and shallow valleys. Elevations vary from 200 to
400 feet above sea level. The weather is generally good with
no associated unusual weather phenomena.

   The Moron AB has an 11,800- by 200-foot runway with
1,000-foot overruns and a 50-foot asphalt-stabilized
shoulder. Communication at Moron includes a dedicated cir-
cuit to KSC/Cape Canaveral Air Force Station via Goddard
Space Flight Center and the NASCOM Madrid Switching Center,
three circuits via satellite, and an 800-line automatic dial
exchange.

ZARAGOZA AIR BASE, SPAIN

   Zaragoza AB was designated a TAL site in 1983. It is the
primary TAL site for high inclination launches and like
Moron is a Spanish base used by both the U.S. and Spain. Lo-
cated northwest of the town of Zaragoza, it has two parallel
runways, one 9,923 feet by 197 feet and the other 12,109
feet by 197 feet. The longer runway has 1,000 feet of over-
run and is used primarily by the U.S. Air Force. Its length
and the prevailing winds make the longer runway the most
suitable for Shuttle use.

   Communications at Zaragoza include one dedicated circuit
to KSC/CCAFS via Goddard and the Madrid switch, three cir-
cuits via satellite, and an automated dial exchange. An
AUTOVON voice circuit is available.

SHUTTLE SUPPORT EQUIPMENT AT TAL SITES

   NASA has enhanced each of the four TAL sites with equip-
ment to support an orbiter landing, including:

     --Navigation and Landing Aids: NASA has equipped each
of the four sites with Shuttle-specific navigation and land-
ing aids. The TACAN, or Tactical Air Navigation system,
works in conjunction with the MSBLS system, or Microwave
Scanning Beam Landing System. Together the two will provide
the orbiter with all the necessary data to make a safe land-
ing. The TACAN is positioned to provide distance and bearing
information to the orbiter. The orbiter will be able to lock
on to the TACAN while still several hundred miles out over
the Atlantic and receive precise guidance information to ef-
fect a successful alignment with the runway. The MSBLS sys-
tem is accurate within five hundredths of a degree and
provides the proper elevation landing angle from about
30,000 feet to touchdown.

   Lighted aim points include six strobe lights located at
6,500 feet from each runway and spaced about two feet apart
on the runway centerline to a point 6,490 feet from each
threshold. They assist the orbiter crew in locating the PAPI
lights.

   PAPI, Precision Approach Path Indicator Lights, with as-
sociated strobes, will be utilized by the orbiter crew to
verify outer glide slope during a landing. Two sets are used
to accommodate high and low wind scenarios. High wind PAPI
lights are 6,500 feet on centerline prior to each threshold
and low wind PAPI lights are 7,500 feet on centerline prior
to each threshold.

   Ball/bar lights will be used by the Shuttle astronauts to
verify proper inner glide slope during landing. The ball/bar
lights are installed along both runways. The ball light is
1,700 feet from the runway threshold, the bar light 2,200
feet.

   Distance-to-go markers will allow the crew to determine
the distance remaining to the end of either runway during
landing and rollout. These markers are installed on each
side of the runway, 1,000 feet apart, starting from each
threshold to the barrier.

   Xenon lights are a high intensity flood light system,
complete with diesel generators, which will provide runway
lighting in the event of a night TAL. The system is portable
and consists of two sets of three lights. A set is installed
on each side of the runway at the threshold, 150 feet from
the centerline on a raised platform truck.

   The ball/bar and PAPI lights, lighted aim points,
distance-to-go markers and Xenon lights are installed prior
to each Shuttle launch and dismantled after it is completed
and stored away.

     --Weather Equipment: Each TAL site has an automated
weather station that transmits via the Geostationary Opera-
tional Environment Satellite (GOES).  During a Shuttle
launch, the Defense Department will provide weather observa-
tions at two of the TAL sites, Moron and Zaragoza, Spain,
while Morocco and The Gambia will handle this function
within their own countries. Responsibility for weather
forecasting will always rest with the NASA Shuttle Meteorol-
ogy Group (SMG).

     --Shuttle Orbiter Arresting System: Three of the TAL
sites, Yundum, Moron and Zaragoza, are equipped with the
Shuttle orbiter arresting system (SOAS), which is a net bar-
rier installed prior to and dismantled after a successful
launch. The SOAS, a self-contained system which can be in-
stalled in eight hours by a crew of eight, is installed
about 800 feet from the end of the pavement to safely stop
an orbiter vehicle if necessary. Ben Guerir with its longer
runway does not require the SOAS.

     --Dedicated Orbiter Ground Support Equipment: Special
orbiter ground support equipment has also been installed and
is stored on-site between missions. These are a hatch open-
ing tool, landing gear lock pins, grounding cable, tow bar,
tow bar adapter and towing vehicle.

     --Fire, Crash and Rescue Resources: A team of NASA
fire, crash and rescue personnel will be on-site during mis-
sion support, supplemented by trained personnel from the
country in question. Fire-fighting equipment is permanently
stored at Ben Guerir; at Banjul, local fire equipment is
used, and at the two Spanish bases U.S. Air Force equipment
is available.

     --Aircraft Support: U.S. Defense Department C-130
aircraft are positioned at Ben Guerir, the primary TAL site
for low inclination launches, and at Banjul and Moron Air
Base. For high inclination launches, a C-130 would be posi-
tioned at Zaragoza Air Base. Each aircraft is staffed with
medical personnel and is capable of transporting the entire
Shuttle crew. The C-130s will also be used to transport TAL
ground personnel between sites. Additional aircraft, person-
nel and equipment will be flown over from the U.S. to bring
the orbiter back. Pararescue personnel are available to as-
sist with search and rescue operations and medical treatment
in the event of a crew bailout from the orbiter.

WHEN A TAL OCCURS

   About a week prior to a Shuttle launch, a team of U.S.
personnel will arrive and activate the TAL sites identified
for that mission. This mission support team will include up
to about 50 government personnel headed by the NASA ground
operations manager. The Defense Department medical team will
arrive on-site 24 hours prior to launch.

   If a TAL is declared, the TAL site will be notified by
NASA that the Shuttle is going to land there. The U.S. State
Department will notify the country involved and the air
space will be cleared.

   The time from declaration of a TAL to a landing is es-
timated at about 20-25 minutes. Once the Shuttle crew com-
mander punches the TAL call into the pre-programmed orbiter
computers, the vehicle will automatically be steered toward
the  landing site. The orbiter will roll heads-up before
main engine cutoff and all extra fuel will be dumped to in-
crease vehicle performance by decreasing its weight,
properly placing the center of gravity and lowering landing
weight. The Shuttle will automatically fly to an altitude of
about 360,000 feet and the remaining engines will cut off at
the correct velocity. The external tank will be jettisoned
after engine shutdown, as in a nominal launch, and then
tumbled to insure that it does not glide into the Earth's
atmosphere.

   A pre-loaded reentry program will then go into effect,
with the orbiter encountering the atmosphere and a normal
reentry planned. Ten minutes before landing, normal com-
munications will resume through the Tracking and Data Relay
Satellite (TDRS). The orbiter crew will contact the TAL site
on UHF radio and begin their approach to the field in
preparation for landing. Data received from the TAL TACAN is
received and used to update the orbiter's inertial guidance
system 200 miles from touchdown as the spacecraft slows to
Mach 7.

   At landing minus 6 minutes, the orbiter will enter what
is considered to be the terminal area. At this point its al-
titude is still quite high, 82,000 feet, and its speed
supersonic--Mach 2.5. Its flight is akin to a conventional
aircraft's except that its speedbrakes will be left open to
provide greater stability during supersonic flight.

   Approximately five minutes before touchdown, the orbiter
will pass over the center of the runway with the speed drop-
ping to Mach 1. About four minutes before landing, the crew
commander will take over manual control of the spacecraft.
This will be just prior to a maneuver known as intercepting
the heading alignment circle. This is a large 270 degree
turn to align the orbiter with the center line of the run-
way.

   At landing minus 2 minutes, the orbiter will enter its
final approach at an altitude of 13,000 feet. The
speedbrakes are closed at an altitude of 3,000 feet. At an
altitude of 1,800 feet and 7,500 feet from the end of the
runway, the commander begins a preflare maneuver to pull up
from a glide angle of 17 degrees to a more gentle slope of
one and a half degrees. Touchdown speed is 195 knots.

   The Shuttle flight crew is expected to give its first
report to Mission Control at T+50 minutes. Exit from the or-
biter will occur at about one hour and ten minutes into the
launch cycle. At about T+4 hours, the crew will depart the
TAL site aboard the C-130 and will be taken, if uninjured,
to an evacuation site--the nearest U.S. military base--or to
appropriate medical facilities if injured. Some 16 hours
into the launch, a KC-135 aircraft will arrive at the
evacuation site and, depending on the crew sleep cycle, will
take the crew back to the U.S. The flight crew will remain
together unless medical circumstances dictate otherwise.


Ground Operations

   Once the crew has left the orbiter, the crew hatch will
be closed and special equipment installed to prepare the
vehicle for transport. It will then be towed to a remote
deservicing park site.

   Safing and deservicing of the orbiter will be initiated
by the Rapid Response Team. The RRT includes up to 50
workers and equipment, most of it coming from Edwards AFB,
Calif., where the majority of Shuttle landings have taken
place. Depending on the situation, the RRT should arrive at
the TAL site within a day aboard a C-141 aircraft.

   Following the advance RRT contingent, additional person-
nel and equipment will brought in to effect the orbiter tur-
naround. NASA estimates it will take some 55 C-141 aircraft
and 30 C-5A aircraft sorties and a total of about 450 per-
sonnel to complete turnaround. The TAL site ground opera-
tions manager will be in charge.

   A Mishap Investigation Team (MIT) will also travel im-
mediately to the site to collect data on the unscheduled
landing.

   Payloads and/or airborne support equipment will remain
aboard the orbiter for the flight back to Kennedy Space Cen-
ter unless the capability of the Shuttle Carrier Aircraft
(SCA), landing site location or other requirements dictate
otherwise.