STS Aborts

1
STS Aborts
2
STS Aborts

• Abort Types
• There are two classifications of aborts available
  to the crews during the launch phase of the Space
  Shuttle mission. The first is the intact abort
  which enlist various procedures to return the
  vehicle for a landing at the launch or alternate
  sites. The second is the contingency abort that
  is used for crew survival in a controlled glide
  by abandoning the vehicle with a crew-parachute
  landing.
• Intact abortsThe intact aborts include from most
  desirable to least desirable
• Abort To Orbit (ATO)
• Abort Once Around (AOA)
• Trans Atlantic Landing (TAL)
• Return To Launch Site (RTLS)

3
STS Aborts

• Abort Types
• Contingency abort
• A contingency abort used for crew survival in
  more serious flight conditions caused by the loss
  of more than one SSME, or failures in other
  systems that do not allow a landing or RTLS
  abort. Most three engine-out ascent scenarios
  necessitates this abort mode in which case the
  orbiter would have to be ditched, although a
  contingency abort is never chosen if another
  abort option exists. The in-flight crew escape
  system would be used before ditching the Orbiter.

4
STS Aborts

• Decision on abort modes
• The decision on when to abort a mission and which
  abort mode to execute is based generally on the
  highest preferred type of abort that is allowed
  by the remaining performance of STS/Orbiter
• Timing for the abort is dependent on the severity
  of the system/engine failure as is the abort mode
  which makes the decision process a complex
  procedure of determining the cause and timing of
  the failure causing the abort quickly

5
STS Aborts

• Decision on abort modes
• If communications exists between the Orbiter crew
  and NASA's Mission Control Center-Houston
• Calling the abort is the responsibility of the
  Mission Control Center since it has more complete
  knowledge of the Orbiter and its position than
  the crew
• If communications are lost
• Crew has onboard information and equipment to
  allow them to determine the optimum abort
  procedure

6
STS Aborts
7
STS Aborts - ATO

• Intact Aborts
• Abort To Orbit (ATO)
• An ATO is an abort mode that allows the Orbiter
  to achieve a lower orbital altitude when
  performance has been lost
• Temporary lower orbit can be used for
  transferring to the planned orbit if possible, or
  to execute a modified deorbit for a for landing
• Most preferable abort mode

8
STS Aborts - ATO

• Intact Aborts
• Abort To Orbit (ATO)
• Only one abort executed in the STS program
• Challenger flight launched on 29 July 1985
• 5 min 45 sec into ascent a sensor problem caused
  center engine 1 to shutdown prematurely
• Loss of thrust precluded Challenger from
  achieving its 190 nm orbit
• Instead placed in a 140 nm orbit as part of the
  ATO procedure
• Lower orbit had little impact on the mission
• Crew and Orbiter met objectives successfully

9
STS Aborts - ATO
10
STS Aborts - AOA

• Intact Aborts
• Orbit Once-Around (AOA)
• The Abort Once Around allows the vehicle to
  complete one orbit to setup normal entry and
  landing where reduced Orbiter performance or
  reduced fuel does not allow entry to the planned
  orbit
• AOA uses two OMS burns
• Second most preferable abort mode
• Approximately 90 minute return time
• Landing sites for the AOA are at KSC, White Sands
  NM, or Edwards AFB

11
STS Aborts - AOA
12
STS Aborts - TAL

• Intact Aborts
• Transoceanic Abort Landing (TAL)
• The Transoceanic Abort Landing is employed for an
  engine failure beyond the RTLS limit but before
  reaching the Abort Once Around point.
• Suborbital TAL procedure includes one or more
  preselected landing sites on the European and
  African continents based on the orbital
  inclination

13
STS Aborts - TAL

• Intact Aborts
• Transoceanic Abort Landing (TAL)
• Does not need an OMS burn, but does require a
  OMS/RCS propellant dump in flight
• TAL is the third most preferable abort
• Landing site based on flight track (inclination)
• Moron, Spain (MRN)
• Dakar, Senegal (ZZA)
• Ben Guerur, Morocco  (BEN)

14
STS Aborts - TAL
15
STS Aborts - RTLS

• Intact Aborts
• Return To Launch Site (RTLS)
• The RTLS is the most complex and least preferable
  intact abort
• Part of the post-failure flight can be under SRB
  thrust, and following separation, under SSME
  power for a return to the landing site
• Part of which is in retrograde (reverse) flight
  under SSME power

16
STS Aborts - RTLS

• Intact Aborts
• Return To Launch Site (RTLS)
• Used For loss of single SSME between liftoff and
  420s where not enough fuel remains for return and
  for three-engine return
• Executed between liftoff and 3m 34s
• Approximately 24 minute return time

17
STS Aborts - RTLS

• Intact Aborts
• Return To Launch Site (RTLS)
• The RTLS is divided into three stages
• 1. Powered stage - SSME and SRB still operating
• Flight must continue until SRB separation to
  avoid catastrophic structural failure
• Flight is continued downrange to burn enough fuel
  to allow turn, then return to KSC landing strip
• Turn is executed during powered thrust (thrust
  reverse to flight during last part of turn)

18
STS Aborts - RTLS

• Intact Aborts
• Return To Launch Site (RTLS)
• 2. ET separation
• RCS used to separate Orbiter from ET
• 3. Glide phase
• Normal gliding approach to landing

19
STS Aborts - RTLS
20
STS Aborts - Contingency

• Contingency Abort
• Contingency aborts are caused by loss of more
  than one main engine or failures in other
  critical systems
• Such an abort would maintain orbiter integrity
  for in-flight crew escape if a landing cannot be
  made at a suitable landing site
• Contingency aborts due to system failures other
  than those involving the main engines would
  normally result in an intact recovery of vehicle
  and crew

21
STS Aborts - Contingency

• Contingency Abort
• Loss of more than one main engine could result in
  a safe runway landing
• In most three-engine-out cases during ascent, the
  orbiter would have to be ditched
• The in-flight crew escape system would be used
  before ditching the Orbiter
• Altitude range for bailout approximately 20,000
  to 10,000

22
STS Aborts Contingency
23

• STS Landing Sites

24
End-of-Mission Sites

• Kennedy Space Center, Florida
• Edwards Air Force Base, California
• White Sands Space Harbor, New Mexico

25
STS Landing Sites U.S. Canada
26
STS Augmented Landing Sites

• Istres Air Base, France
• Moron Air Base, Spain
• Zaragoza Air Base, Spain (high inclination orbit
  only)
• Yundum Airport, Banjul, The Gambia (low
  inclination orbit only)
• Base Aerienne, Ben Guerir, Morocco
• Dakar, Senegal

27
STS Augmented Landing Sites - Atlantic
28
STS Emergency Landing Sites

• Dyess Air Force Base, Texas
• Ellsworth Air Force Base, South Dakota
• Grant County (Moses Lake), Washington
• Lincoln Municipal Airport, Nebraska
• Mountain Home Air Force Base, Idaho
• Orlando International Airport, Florida
• Tamanrassett, Algeria
• Amberley, Australia
• Darwin, Australia
• Lajes Air Base, Azores (mid inclination orbit
  only)
• Nassau, Bahamas
• Gran Canaria (Las Palmas), Canary Islands
• Amilcar Cabral, Cape Verde
• Naval Support Activity Souda Bay, Crete (mid
  inclination orbit only)
• Navy Support Facility Diego Garcia, Chagos Island
  
• Koln-Bonn, Germany
• Roberts International Airport (Monrovia), Liberia
  
• King Khalid International Airport, Saudi Arabia
• Hoedspruit, South Africa

29
STS Launch Abort Sites

• Myrtle Beach, South Carolina (high inclination
  orbit only)
• Marine Corps Air Station Cherry Point, North
  Carolina (high inclination orbit only)
• Naval Air Station Oceana, Virginia Beach,
  Virginia (high inclination orbit only)
• Dover Air Force Base, Delaware (high inclination
  orbit only)
• Otis Air National Guard Base, Massachusetts (high
  inclination orbit only)
• Pease Air National Guard Base, New Hampshire
  (high inclination orbit only)
• Naval Air Station Bermuda (low or mid inclination
  orbit only)
• Gander, Newfoundland, Canada
• Goose Bay, Newfoundland, Canada
• Halifax International Airport, Nova Scotia,
  Canada
• St. John's, Newfoundland, Canada
• Stephenville, Newfoundland, Canada

30
Finis