Space Shuttle abort modes
Encyclopedia
A Space Shuttle abort was an emergency procedure due to equipment failure on NASA
's Space Shuttle
, most commonly during ascent. A main engine
failure is a typical abort scenario. There are fewer abort options during reentry and descent. For example, the Columbia disaster
happened during reentry
, and there were no alternatives in that portion of flight.
Later in descent certain failures are survivable, although not usually classified as an abort. For example, a flight control system
problem or multiple auxiliary power unit
failure could make reaching a landing site impossible, thus requiring astronaut
s to bail out
.
The choice of abort mode depended on how urgent the situation was, and what emergency landing site could be reached. The abort modes covered a wide range of potential problems, but the most commonly expected problem was Space Shuttle Main Engine
(SSME) failure, causing inability either to cross the Atlantic or to achieve orbit, depending on timing and number of failed engines. Other possible non-engine failures possibly necessitating an abort included multiple auxiliary power unit
(APU) failure, cabin leak, and external tank leak (ullage leak).
at T - 0 seconds, the main engines could be shut down. This was called a "Redundant Set Launch Sequencer Abort", and has happened five times, on STS-41-D
, STS-51-F
, STS-51
, STS-55
, and STS-68
. It has always happened under computer (not human) control, caused by computers sensing a problem with the main engines after starting but before the SRBs ignite. The SRBs could not be turned off once ignited, and afterwards the shuttle was committed to take off. If an event such as an SSME failure requiring an abort happened after SRB ignition, acting on the abort must wait until SRB burnout 123 seconds after launch. No abort options existed if that wait was not possible.
There were four intact abort modes for the Space Shuttle. Intact aborts were designed to provide a safe return of the orbiter to a planned landing site or to a lower orbit than planned for the mission.
until the solid rocket boosters
are jettisoned. It then pitches
around, so the SSMEs are firing retrograde. This maneuver occurs in a near vacuum above the appreciable atmosphere and is conceptually no different from the OMS engines firing retrograde to de-orbit. The main engines continue burning until downrange
velocity is killed and the vehicle is headed back toward the launch site at sufficient velocity to reach a runway. Then the SSMEs are stopped, the external tank
is jettisoned, and the orbiter makes a normal gliding landing on the runway at Kennedy Space Center
about 25 minutes after lift-off. The CAPCOM calls out the point in the ascent at which an RTLS becomes no longer possible as "negative return", approximately four minutes after lift-off. This abort mode was never actually needed during the history of the Shuttle program.
A TAL abort would be declared between roughly T+2:30 minutes (2 minutes, 30 seconds after liftoff) and Main Engine Cutoff (MECO), about T+8:30 minutes. The Shuttle would then land at a predesignated friendly airstrip in Europe. The four present TAL sites are Istres Air Base
in France, Zaragoza
or Morón
air bases, both in Spain, and RAF Fairford
in England. Prior to a Shuttle launch, two of them are selected depending on the flight plan, and staffed with standby personnel in case they are used. The list of TAL sites has changed over time; most recently Ben Guerir Air Base
in Morocco
(TAL site from July 1988–June 2002) was eliminated due to terrorist attack concerns. Other previous TAL sites have included Lajes Air Base, Terceira, Azores, Mallam Aminu Kano International Airport
, Kano, Nigeria; Mataveri International Airport
, Easter Island
, Chile (for Vandenberg launches); Rota
, Spain; Casablanca
, Morocco; Banjul
, Gambia; and Dakar
, Senegal.
Preparations of TAL sites take 4–5 days and begin a week before a launch with the majority of NASA, DOD and contractor personnel arriving 48 hours before launch. Additionally two C-130 aircraft from the Manned Space Flight support office from the adjacent Patrick Air Force Base
including 8 crew, nine pararescue jumpers, two flight surgeon
s, a nurse and medical technician, along with 2,500 pounds of medical equipment are deployed to the Zaragoza site, Istres site or both. One or more C-21 or a C-12
aircraft are also deployed to provide weather reconnaissance in the event of an abort with a TALCOM, or astronaut flight controller aboard for communications with the shuttle pilot and commander.
This abort mode was never actually needed during the history of the Shuttle program.
, which continued despite the abort to a lower orbit. The Mission Control Center in Houston
(located at Lyndon B. Johnson Space Center
) observed an SSME failure and called "Challenger--Houston, Abort ATO. Abort ATO".
The moment at which an ATO becomes possible is referred to as the "press to ATO" moment. In an ATO situation, the spacecraft commander rotates the cockpit abort mode switch to the ATO position and depresses the abort push button. This initiates the flight control software routines which handle the abort. In the event of lost communications, the spacecraft commander can make the abort decision and take action independently.
A hydrogen fuel leak in one of the SSMEs
on STS-93
resulted in a slightly lower orbit than anticipated, but was not an ATO; if the leak had been more severe, it might have necessitated an ATO, RTLS, or TAL abort.
Sites in which an Orbiter has landed are listed in Bold, but none are emergency landings.
Unlike all previous U.S. manned launch vehicles, the shuttle never flew unmanned test flights. To provide an incremental non-orbital manned test, NASA considered making the first mission an RTLS abort. However, STS-1
commander John Young declined, saying, "let's not practice Russian roulette
."
Were the Orbiter unable to reach a runway, it could ditch in water, or could land on terrain other than a landing site. It would be unlikely for the flight crew still on board to survive. However, for ascent abort scenarios where controlled gliding flight is achievable, a bailout is possible. For more details, see "Post-Challenger abort enhancements" below.
In the two disasters, things went wrong so fast that little could be done. In the case of Challenger
, the Space Shuttle Solid Rocket Booster
s were still burning as they tore free from the rest of the stack, one likely impacting the external tank. The orbiter disintegrated almost instantly from aerodynamic stresses as the stack broke up. The Columbia disaster
occurred high in the atmosphere during reentry. Even if the crew had been able to bail out, they would have been killed by the heat generated at hypersonic velocities.
during STS-51-L
, very limited ascent abort options existed. Failure of only a single SSME
was survivable prior to about 350 seconds into the ascent. Two or three failed SSMEs prior to that point would mean loss of crew and vehicle (LOCV), since no bailout option existed. Two or three failed SSMEs while the SRBs are firing would probably have overstressed the struts attaching the orbiter to the external tank, causing vehicle breakup. For that reason, a Return To Launch Site (RTLS) abort was not possible in the event of two or three failed SSMEs. Studies showed an ocean ditching was not survivable. Furthermore, the loss of a second or third SSME at almost any time during an RTLS abort would have caused a LOCV.
After the loss of Challenger in STS-51-L
, numerous abort enhancements were added. With those enhancements, the loss of two SSMEs is now survivable for the crew throughout the entire ascent, and the vehicle could survive and land for large portions of the ascent. Loss of three SSMEs is survivable for the crew for most of the ascent, although survival in the event of three failed SSMEs before T+90 seconds is questionable. However, it is conceivable that failure of three SSMEs just after liftoff might be survivable, since the SRBs provide enough thrust and steering authority to continue the ascent until a bailout or RTLS. The struts attaching the orbiter to the external tank were strengthened to better endure a multiple SSME failure.
A particular significant enhancement was bailout capability. This is not ejection as with a fighter plane, but an Inflight Crew Escape System (ICES). The vehicle is put in a stable glide on autopilot, the hatch is blown, and the crew slides out a pole to clear the orbiter's left wing. They would then parachute to earth or the sea. While this may at first appear only usable under rare conditions, there are many failure modes where reaching an emergency landing site is not possible yet the vehicle is still intact and under control. Before the Challenger disaster, this almost happened on STS-51-F
, when a single SSME failed at about T+345 seconds. The orbiter in that case was also Challenger. A second SSME almost failed due to a spurious temperature reading; fortunately the engine shutdown was inhibited by a quick-thinking flight controller. If the second SSME failed within about 69 seconds of the first, there would have been insufficient energy to cross the Atlantic. Without bailout capability the entire crew would be lost. After the loss of Challenger, those types of failures have been made survivable. To facilitate high altitude bailouts, the crew now wears Advanced Crew Escape Suit
s during ascent and descent. Before the Challenger disaster, crews for operational missions wore only fabric flight suits.
Another post-Challenger enhancement was the addition of East Coast Abort Landings (ECAL). High-inclination launches (including all ISS
missions) can now reach an emergency runway on the East Coast of the United States under certain conditions.
An ECAL abort is similar to RTLS, but instead of landing at the Kennedy Space Center, the Orbiter would attempt to land at another site along the east coast of North America. Various emergency landing sites extend from South Carolina and Bermuda up into Newfoundland, Canada. ECAL is a contingency abort that is less desirable than an intact abort, primarily because there is so little time to choose the landing site and prepare for the Orbiter's arrival. The ECAL emergency sites are not as well equipped to accommodate an Orbiter landing.
Numerous other abort refinements were added, mainly involving improved software for managing vehicle energy in various abort scenarios. These enable a greater chance of reaching an emergency runway for various SSME failure scenarios.
, has been discussed many times for the shuttle. After the Challenger and Columbia losses, great interest was expressed in this. All previous US manned space vehicles had launch escape systems, although none were ever used.
The Soviet shuttle Buran was planned to be fitted with the crew emergency escape system, which would have included K-36RB (K-36M-11F35) seats and the "Strizh" full-pressure suit, qualified for altitudes up to 30,000 m and speeds up to Mach 3. Buran flew only once in fully automated mode without a crew, thus the seats were never installed and were never tested in real human space flight.
or cabin escape system where the crew ejects in protective capsules, or the entire cabin is ejected. Such systems have been used on several military aircraft. The B-58 Hustler
and XB-70 Valkyrie
used capsule ejection. The General Dynamics F-111
and early prototypes of the Rockwell B-1 bomber
used cabin ejection.
Like ejection seats, capsule ejection for the shuttle would be difficult because no easy way exists to exit the vehicle. Several crewmembers sit in the middeck, surrounded by substantial vehicle structure.
Cabin ejection would work for a much larger portion of the flight envelope than ejection seats, as the crew would be protected from temperature, wind blast, and lack of oxygen or vacuum. In theory an ejection cabin could be designed to withstand reentry, although that would entail additional cost, weight and complexity. Cabin ejection was not pursued for several reasons:
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
, most commonly during ascent. A main engine
Space Shuttle main engine
The RS-25, otherwise known as the Space Shuttle Main Engine , is a reusable liquid-fuel rocket engine built by Pratt & Whitney Rocketdyne for the Space Shuttle, running on liquid hydrogen and oxygen. Each Space Shuttle was propelled by three SSMEs mated to one powerhead...
failure is a typical abort scenario. There are fewer abort options during reentry and descent. For example, the Columbia disaster
Space Shuttle Columbia disaster
The Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members...
happened during reentry
Atmospheric reentry
Atmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line,...
, and there were no alternatives in that portion of flight.
Later in descent certain failures are survivable, although not usually classified as an abort. For example, a flight control system
Aircraft flight control systems
A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight...
problem or multiple auxiliary power unit
Auxiliary power unit
An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...
failure could make reaching a landing site impossible, thus requiring astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....
s to bail out
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...
.
Ascent abort modes
There were five abort modes available during ascent, in addition to pad (RSLS) aborts. These were classified as intact aborts and contingency aborts.The choice of abort mode depended on how urgent the situation was, and what emergency landing site could be reached. The abort modes covered a wide range of potential problems, but the most commonly expected problem was Space Shuttle Main Engine
Space Shuttle main engine
The RS-25, otherwise known as the Space Shuttle Main Engine , is a reusable liquid-fuel rocket engine built by Pratt & Whitney Rocketdyne for the Space Shuttle, running on liquid hydrogen and oxygen. Each Space Shuttle was propelled by three SSMEs mated to one powerhead...
(SSME) failure, causing inability either to cross the Atlantic or to achieve orbit, depending on timing and number of failed engines. Other possible non-engine failures possibly necessitating an abort included multiple auxiliary power unit
Auxiliary power unit
An auxiliary power unit is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft, as well as some large land vehicles.-Function:...
(APU) failure, cabin leak, and external tank leak (ullage leak).
Redundant Set Launch Sequencer (RSLS) Abort
The main engines were ignited roughly 6.6 seconds before liftoff. From that point to ignition of the Solid Rocket BoostersSpace Shuttle Solid Rocket Booster
The Space Shuttle Solid Rocket Boosters were the pair of large solid rockets used by the United States' NASA Space Shuttle during the first two minutes of powered flight. Together they provided about 83% of liftoff thrust for the Space Shuttle. They were located on either side of the rusty or...
at T - 0 seconds, the main engines could be shut down. This was called a "Redundant Set Launch Sequencer Abort", and has happened five times, on STS-41-D
STS-41-D
STS-41-D was the first flight of NASA's Space Shuttle orbiter Discovery. It was the 12th mission of the Space Shuttle program, and was launched from Kennedy Space Center, Florida, on 30 August 1984...
, STS-51-F
STS-51-F
STS-51-F was the nineteenth flight of NASA's Space Shuttle program, and the eighth flight of Space Shuttle Challenger...
, STS-51
STS-51
STS-51 was a Space Shuttle Discovery mission that launched the Advanced Communications Technology Satellite ACTS in September 1993. The flight also featured the deployment and retrieval of the SPAS-ORFEUS satellite and its IMAX camera, which captured spectacular footage of Discovery in space...
, STS-55
STS-55
-Backup crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 28.5°*Period: 90.7 min-Mission highlights:...
, and STS-68
STS-68
STS-68 was a human spaceflight mission using that launched from Kennedy Space Center, Florida on 1994-09-30.-Crew:-Launch:Launch 30 September 1994 at 7:16:00.068 am EDT from Kennedy Space Center Launch Pad 39-A. The Launch window opened at 7:16 am EDT with a 2 hour 30 minute window. Orbiter...
. It has always happened under computer (not human) control, caused by computers sensing a problem with the main engines after starting but before the SRBs ignite. The SRBs could not be turned off once ignited, and afterwards the shuttle was committed to take off. If an event such as an SSME failure requiring an abort happened after SRB ignition, acting on the abort must wait until SRB burnout 123 seconds after launch. No abort options existed if that wait was not possible.
Intact abort modes
Return To Launch Site (RTLS)
In a Return To Launch Site (RTLS) abort, the Shuttle continues downrangeDownrange
Downrange is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. More often, it is used as an adverb or adjective specifying the direction of that travel being measured in a horizontal direction....
until the solid rocket boosters
Space Shuttle Solid Rocket Booster
The Space Shuttle Solid Rocket Boosters were the pair of large solid rockets used by the United States' NASA Space Shuttle during the first two minutes of powered flight. Together they provided about 83% of liftoff thrust for the Space Shuttle. They were located on either side of the rusty or...
are jettisoned. It then pitches
Flight dynamics
Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...
around, so the SSMEs are firing retrograde. This maneuver occurs in a near vacuum above the appreciable atmosphere and is conceptually no different from the OMS engines firing retrograde to de-orbit. The main engines continue burning until downrange
Downrange
Downrange is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. More often, it is used as an adverb or adjective specifying the direction of that travel being measured in a horizontal direction....
velocity is killed and the vehicle is headed back toward the launch site at sufficient velocity to reach a runway. Then the SSMEs are stopped, the external tank
Space Shuttle external tank
A Space Shuttle External Tank is the component of the Space Shuttle launch vehicle that contains the liquid hydrogen fuel and liquid oxygen oxidizer. During lift-off and ascent it supplies the fuel and oxidizer under pressure to the three Space Shuttle Main Engines in the orbiter...
is jettisoned, and the orbiter makes a normal gliding landing on the runway at Kennedy Space Center
Kennedy Space Center
The John F. Kennedy Space Center is the NASA installation that has been the launch site for every United States human space flight since 1968. Although such flights are currently on hiatus, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program...
about 25 minutes after lift-off. The CAPCOM calls out the point in the ascent at which an RTLS becomes no longer possible as "negative return", approximately four minutes after lift-off. This abort mode was never actually needed during the history of the Shuttle program.
Transoceanic Abort Landing (TAL)
A Transoceanic Abort Landing (TAL) involves landing at a predetermined location in Africa or western Europe about 25 to 30 minutes after lift-off. It is used when velocity, altitude and distance downrange do not allow return to the launch point via RTLS. It is also used when a less time-critical failure does not require the faster but possibly more stressful RTLS abort.A TAL abort would be declared between roughly T+2:30 minutes (2 minutes, 30 seconds after liftoff) and Main Engine Cutoff (MECO), about T+8:30 minutes. The Shuttle would then land at a predesignated friendly airstrip in Europe. The four present TAL sites are Istres Air Base
Istres Air Base
Istres-Le Tubé Air Base is a large multi-role tasked French Air Force base located near Istres, northwest of Marseille, France. The airport facilities are also known as Istres - Le Tubé .- Armée de l'air :...
in France, Zaragoza
Zaragoza Air Base
Zaragoza Air Base was a NATO military airbase located near Zaragoza, Spain. It was located west of Zaragoza, west of Barcelona, and northeast of Madrid.It was closed as a NATO base in in April 1992...
or Morón
Morón Air Base
Morón Air Base is located at in southern Spain, approximately southeast of the city of Seville and northeast of Naval Station Rota. The base gets its name from the nearby town of Morón de la Frontera - although its is actually located in the municipality of Arahal.Morón's massive flight line,...
air bases, both in Spain, and RAF Fairford
RAF Fairford
RAF Fairford is a Royal Air Force station in Gloucestershire, England. It is a standby airfield, not in everyday use. Its most prominent use in recent years has been as an airfield for United States Air Force B-52s during the 2003 Iraq War, Operation Allied Force in 1999, and the first Gulf War in...
in England. Prior to a Shuttle launch, two of them are selected depending on the flight plan, and staffed with standby personnel in case they are used. The list of TAL sites has changed over time; most recently Ben Guerir Air Base
Ben Guerir Air Base
Ben Guerir Air Base is a former United States Air Force base located in Morocco, later operated by the Royal Moroccan Air Force, which served as a Transatlantic Abort Landing site for the Space Shuttle...
in Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
(TAL site from July 1988–June 2002) was eliminated due to terrorist attack concerns. Other previous TAL sites have included Lajes Air Base, Terceira, Azores, Mallam Aminu Kano International Airport
Mallam Aminu Kano International Airport
Mallam Aminu Kano International Airport is located in Kano, a city in the Kano State of Nigeria. It is the main airport serving northern Nigeria and was named after Nigerian politician Aminu Kano. The airport consists of an international and a domestic terminal. Both terminals share the same...
, Kano, Nigeria; Mataveri International Airport
Mataveri International Airport
-See also:*Extreme points of Earth*Shuttle Down, a 1980 novel by American author G. Harry Stine , which gives a fictional account of the Space Shuttle Atlantis making an emergency landing.-External links:***...
, Easter Island
Easter Island
Easter Island is a Polynesian island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian triangle. A special territory of Chile that was annexed in 1888, Easter Island is famous for its 887 extant monumental statues, called moai, created by the early Rapanui people...
, Chile (for Vandenberg launches); Rota
Rota, Spain
-External references:*, official website * On-line since 1999! News, premiere information, pictures, weather, etc. Into Spanish, English... ****- External links :...
, Spain; Casablanca
Casablanca
Casablanca is a city in western Morocco, located on the Atlantic Ocean. It is the capital of the Grand Casablanca region.Casablanca is Morocco's largest city as well as its chief port. It is also the biggest city in the Maghreb. The 2004 census recorded a population of 2,949,805 in the prefecture...
, Morocco; Banjul
Banjul
-Transport:Ferries sail from Banjul to Barra. The city is served by the Banjul International Airport. Banjul is on the Trans–West African Coastal Highway connecting it to Dakar and Bissau, and will eventually provide a paved highway link to 11 other nations of ECOWAS.Banjul International Airport...
, Gambia; and Dakar
Dakar
Dakar is the capital city and largest city of Senegal. It is located on the Cap-Vert Peninsula on the Atlantic coast and is the westernmost city on the African mainland...
, Senegal.
Preparations of TAL sites take 4–5 days and begin a week before a launch with the majority of NASA, DOD and contractor personnel arriving 48 hours before launch. Additionally two C-130 aircraft from the Manned Space Flight support office from the adjacent Patrick Air Force Base
Patrick Air Force Base
Patrick Air Force Base is a United States Air Force Base located between Satellite Beach and Cocoa Beach, in Brevard County, Florida, United States. It was named in honor of Major General Mason Patrick. An Air Force Space Command base, it is home to the 45th Space Wing...
including 8 crew, nine pararescue jumpers, two flight surgeon
Flight surgeon
A flight surgeon is a military medical officer assigned to duties in the clinical field variously known as aviation medicine, aerospace medicine, or flight medicine...
s, a nurse and medical technician, along with 2,500 pounds of medical equipment are deployed to the Zaragoza site, Istres site or both. One or more C-21 or a C-12
C-12 Huron
The C-12 Huron is the military designation for a series of twin-engine turboprop aircraft based on the Beechcraft Super King Air and Beechcraft 1900. C-12 variants are used by the United States Air Force, United States Army, United States Navy and United States Marine Corps...
aircraft are also deployed to provide weather reconnaissance in the event of an abort with a TALCOM, or astronaut flight controller aboard for communications with the shuttle pilot and commander.
This abort mode was never actually needed during the history of the Shuttle program.
Abort Once Around (AOA)
An Abort Once Around (AOA) is available when the shuttle cannot reach a stable orbit but has sufficient velocity to circle the earth once and land, about 90 minutes after lift-off. The time window for using the AOA abort is very short – just a few seconds between the TAL and ATO abort opportunities. Therefore, taking this option would be very unlikely. This abort mode was never actually needed during the history of the Shuttle program.Abort to Orbit (ATO)
An Abort to Orbit (ATO) is available when the intended orbit cannot be reached but a lower stable orbit is possible. This occurred on mission STS-51-FSTS-51-F
STS-51-F was the nineteenth flight of NASA's Space Shuttle program, and the eighth flight of Space Shuttle Challenger...
, which continued despite the abort to a lower orbit. The Mission Control Center in Houston
Houston, Texas
Houston is the fourth-largest city in the United States, and the largest city in the state of Texas. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of . Houston is the seat of Harris County and the economic center of , which is the ...
(located at Lyndon B. Johnson Space Center
Lyndon B. Johnson Space Center
The Lyndon B. Johnson Space Center is the National Aeronautics and Space Administration's center for human spaceflight training, research and flight control. The center consists of a complex of 100 buildings constructed on 1,620 acres in Houston, Texas, USA...
) observed an SSME failure and called "Challenger--Houston, Abort ATO. Abort ATO".
The moment at which an ATO becomes possible is referred to as the "press to ATO" moment. In an ATO situation, the spacecraft commander rotates the cockpit abort mode switch to the ATO position and depresses the abort push button. This initiates the flight control software routines which handle the abort. In the event of lost communications, the spacecraft commander can make the abort decision and take action independently.
A hydrogen fuel leak in one of the SSMEs
Space Shuttle main engine
The RS-25, otherwise known as the Space Shuttle Main Engine , is a reusable liquid-fuel rocket engine built by Pratt & Whitney Rocketdyne for the Space Shuttle, running on liquid hydrogen and oxygen. Each Space Shuttle was propelled by three SSMEs mated to one powerhead...
on STS-93
STS-93
STS-93 marked the 95th launch of the Space Shuttle, the 26th launch of Columbia, and the 21st night launch of a Space Shuttle. Eileen Collins became the first female shuttle Commander on this flight. Its primary payload was the Chandra X-ray Observatory. It would also be the last mission of...
resulted in a slightly lower orbit than anticipated, but was not an ATO; if the leak had been more severe, it might have necessitated an ATO, RTLS, or TAL abort.
Emergency landing sites
Pre-determined emergency landing sites for the Orbiter were determined on a mission-by-mission basis according to the mission profile, weather and regional political situations. Emergency landing sites during the shuttle program included:Sites in which an Orbiter has landed are listed in Bold, but none are emergency landings.
Australia
- Kingsford-Smith International AirportSydney AirportSydney Airport may refer to:* Sydney Airport, also known as Kingsford Smith International Airport, in Sydney, Australia* Sydney/J.A. Douglas McCurdy Airport, in Nova Scotia, Canada...
, SydneySydneySydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
, New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
(until 1986) - RAAF Base AmberleyRAAF Base AmberleyRAAF Base Amberley is a Royal Australian Air Force base located southwest of Ipswich, Queensland and southwest of Brisbane. It is currently home to No. 1 Squadron and No. 6 Squadron , No. 33 Squadron and No. 36 Squadron...
, Ipswich, QueenslandIpswich, QueenslandIpswich is a city in South-East Queensland, Australia. Situated along the Bremer River Valley approximately 40 kilometres away from the state's capital Brisbane. The suburb by the same name forms the city's Central Business District and administrative centre... - RAAF Base DarwinRAAF Base DarwinRAAF Base Darwin is a Royal Australian Air Force base located in the city of Darwin, Northern Territory. The base shares its runway with Darwin International Airport.-History:...
, Darwin, Northern TerritoryDarwin, Northern TerritoryDarwin is the capital city of the Northern Territory, Australia. Situated on the Timor Sea, Darwin has a population of 127,500, making it by far the largest and most populated city in the sparsely populated Northern Territory, but the least populous of all Australia's capital cities... - RAAF Base PearceRAAF Base PearceRAAF Base Pearce is the main RAAF base in Western Australia. The base is located in Bullsbrook, north of Perth. It is used for training by the Royal Australian Air Force and the Republic of Singapore Air Force...
, Perth, Western AustraliaPerth, Western AustraliaPerth is the capital and largest city of the Australian state of Western Australia and the fourth most populous city in Australia. The Perth metropolitan area has an estimated population of almost 1,700,000....
Bermuda
- NAS BermudaNaval Air Station BermudaNaval Air Station Bermuda , was located on St. David's Island, Bermuda from 1970 to 1995, on the former site of Kindley Air Force Base...
, St. David's IslandSt. David's Island, BermudaSt. David's Island is one of the main islands of Bermuda. It is located in the far north of the territory, one of the two similarly sized islands that makeup the majority of St...
Canada
- CFB Goose BayCFB Goose BayCanadian Forces Base Goose Bay , is a Canadian Forces Base located in the town of Happy Valley-Goose Bay, Newfoundland and Labrador....
, Goose BayHappy Valley-Goose Bay, Newfoundland and LabradorHappy Valley – Goose Bay is a Canadian town in the province of Newfoundland and Labrador.Located in the central part of Labrador, the town is the largest population centre in that region. Incorporated in 1973, the town composes the former town of Happy Valley and the Local Improvement District of...
, LabradorNewfoundland and LabradorNewfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400... - Gander International AirportGander International AirportGander International Airport is located in Gander, Newfoundland and Labrador, Canada, and is currently run by the Gander Airport Authority. Canadian Forces Base Gander shares the airfield but is a separate entity from the airport.-Early years and prominence:...
, GanderGander, Newfoundland and LabradorGander is a Canadian town located in the northeastern part of the island of Newfoundland in the province of Newfoundland and Labrador, approximately south of Gander Bay, south of Twillingate and east of Grand Falls-Windsor...
, NewfoundlandNewfoundland and LabradorNewfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400... - Stephenville International Airport, StephenvilleStephenville, Newfoundland and LabradorStephenville is a Canadian town in Newfoundland and Labrador on the west coast of the island of Newfoundland....
, NewfoundlandNewfoundland and LabradorNewfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400... - St. John's International AirportSt. John's International AirportSt. John's International Airport is an international airport located northwest of St. John's, Newfoundland and Labrador, Canada that serves the St. John's Metro Area and the Avalon Peninsula. The airport is part of the National Airports System, and is operated by St...
, St. John'sSt. John's, Newfoundland and LabradorSt. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...
, NewfoundlandNewfoundland and LabradorNewfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...
France
- Istres-Le Tubé Air Base near IstresIstresIstres is a commune in southern France, some 60 km northwest of Marseille. It is in the Provence-Alpes-Côte d'Azur region, in the Bouches-du-Rhône department, of which it is a subprefecture...
, FranceFranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France... - Hao AirportHao AirportHao Airport is an airport on Hao Island in French Polynesia . The airport is 8 km from the village of Otepa.Hao airport has been selected as an emergency landing site for the NASA Space Shuttle.-Airlines and destinations:...
, HaoHao (French Polynesia)Hao, or Haorangi, is a large coral atoll in the central part of the Tuamotu Archipelago. Because of its shape, French explorer Louis Antoine de Bougainville named it Harp Island....
, French PolynesiaFrench PolynesiaFrench Polynesia is an overseas country of the French Republic . It is made up of several groups of Polynesian islands, the most famous island being Tahiti in the Society Islands group, which is also the most populous island and the seat of the capital of the territory...
Portugal
- Lajes FieldLajes FieldLajes Field or Lajes Air Base , officially designated Air Base No. 4 , is a multi-use air field, home to the Portuguese Air Force Base Aérea Nº4 and Azores Air Zone Command , a United States Air Force detachment , and a regional air passenger terminal located near Lajes...
, LajesLajes (Praia da Vitória)Lajes is a civil parish in the municipality of Praia da Vitória, on the island of Terceira in the Portuguese Azores. In 2001, the population was 3753, occupying an area of 12.11 km², in the north-eastern coast of the municipality : it is the second largest and the most populous parish in the... - Beja AirbaseBeja AirbaseBeja Air Base , designated as Air Base No. 11 is one of the most important military airbase in Portugal near the city of Beja, north of Algarve. It is used by the Portuguese Air Force and has two parallel runways in the 01/19 direction, the biggest being 3,500 meters long and 60 meters wide...
, BejaBeja (Portugal)Beja is a city in the Beja Municipality in the Alentejo region, Portugal. The municipality has a total area of 1,147.1 km² and a total population of 34,970 inhabitants. The city proper has a population of 21,658....
United Kingdom
- RAF Brize NortonRAF Brize NortonRAF Brize Norton in Oxfordshire, about west north-west of London, is the largest station of the Royal Air Force. It is close to the settlements of Brize Norton, Carterton and Witney....
, OxfordshireOxfordshireOxfordshire is a county in the South East region of England, bordering on Warwickshire and Northamptonshire , Buckinghamshire , Berkshire , Wiltshire and Gloucestershire ....
, EnglandEnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental... - RAF FairfordRAF FairfordRAF Fairford is a Royal Air Force station in Gloucestershire, England. It is a standby airfield, not in everyday use. Its most prominent use in recent years has been as an airfield for United States Air Force B-52s during the 2003 Iraq War, Operation Allied Force in 1999, and the first Gulf War in...
, GloucestershireGloucestershireGloucestershire is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn, and the entire Forest of Dean....
, EnglandEnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental... - RAF MachrihanishRAF MachrihanishRAF Machrihanish is a former Royal Air Force station located west of Campbeltown at the tip of Kintyre. It is now known as MoD Machrihanish and also incorporates Campbeltown Airport which has commercial flights to Glasgow, operated by Loganair....
, CampbeltownCampbeltownCampbeltown is a town and former royal burgh in Argyll and Bute, Scotland. It lies by Campbeltown Loch on the Kintyre peninsula. Originally known as Kinlochkilkerran , it was renamed in the 17th century as Campbell's Town after Archibald Campbell was granted the site in 1667...
, ScotlandScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the... - RAF MildenhallRAF MildenhallRAF Mildenhall is a Royal Air Force station located at Mildenhall in Suffolk, England. Despite its status as an RAF station, it primarily supports United States Air Force operations and is currently the home of the 100th Air Refueling Wing...
, SuffolkSuffolkSuffolk is a non-metropolitan county of historic origin in East Anglia, England. It has borders with Norfolk to the north, Cambridgeshire to the west and Essex to the south. The North Sea lies to the east...
, EnglandEnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental... - RAF Upper HeyfordRAF Upper HeyfordRAF Upper Heyford was a Royal Air Force station located north-west of Bicester near the village of Upper Heyford, Oxfordshire, England. The base was brought into use for flying in July 1918 by the Royal Flying Corps. During World War II it was used by many units of the RAF, mainly as a training...
, OxfordshireOxfordshireOxfordshire is a county in the South East region of England, bordering on Warwickshire and Northamptonshire , Buckinghamshire , Berkshire , Wiltshire and Gloucestershire ....
, EnglandEnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
(until 1993) - NAF Diego GarciaDiego GarciaDiego Garcia is a tropical, footprint-shaped coral atoll located south of the equator in the central Indian Ocean at 7 degrees, 26 minutes south latitude. It is part of the British Indian Ocean Territory [BIOT] and is positioned at 72°23' east longitude....
, British Indian Ocean TerritoryBritish Indian Ocean TerritoryThe British Indian Ocean Territory or Chagos Islands is an overseas territory of the United Kingdom situated in the Indian Ocean, halfway between Africa and Indonesia... - Doncaster Airport, South YorkshireSouth YorkshireSouth Yorkshire is a metropolitan county in the Yorkshire and the Humber region of England. It has a population of 1.29 million. It consists of four metropolitan boroughs: Barnsley, Doncaster, Rotherham, and City of Sheffield...
, EnglandEnglandEngland is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
United States
- Andersen Air Force BaseAndersen Air Force BaseAndersen Air Force Base is a United States Air Force base located approximately northeast of Yigo in the United States territory of Guam....
, GuamGuamGuam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United... - Atlantic City International AirportAtlantic City International AirportAtlantic City International Airport is a joint civil-military public airport located nine nautical miles northwest of the central business district of Atlantic City, in Atlantic County, New Jersey...
, Pomona, NJ - Bangor International AirportBangor International AirportBangor International Airport is a joint civil-military public airport located west of the city of Bangor, in Penobscot County, Maine, United States. It is owned and operated by the City of Bangor and was formerly a military installation known as Dow Air Force Base. The airport possesses a single...
, Bangor, MaineBangor, MaineBangor is a city in and the county seat of Penobscot County, Maine, United States, and the major commercial and cultural center for eastern and northern Maine... - MCAS Cherry PointMarine Corps Air Station Cherry PointMarine Corps Air Station Cherry Point or MCAS Cherry Point is a United States Marine Corps airfield located in Havelock, North Carolina, USA, in the eastern part of the state...
, Havelock, North CarolinaHavelock, North CarolinaHavelock is a city in Craven County, North Carolina, United States. The population was 22,442 at the 2000 census, and estimated to be 21,906 in 2006... - Columbus Air Force BaseColumbus Air Force BaseColumbus Air Force Base is a United States Air Force base located approximately north of Columbus, Mississippi.The host unit at Columbus is the 14th Flying Training Wing assigned to the Air Education and Training Command Nineteenth Air Force. The 14 FTW's mission is to provide specialized...
, Columbus, MississippiColumbus, MississippiColumbus is a city in Lowndes County, Mississippi, United States that lies above the Tombigbee River. It is approximately northeast of Jackson, north of Meridian, south of Tupelo, northwest of Tuscaloosa, Alabama, and west of Birmingham, Alabama. The population was 25,944 at the 2000 census... - Dover Air Force BaseDover Air Force BaseDover Air Force Base or Dover AFB is a United States Air Force base located two miles southeast of the city of Dover, Delaware.-Units:...
, Dover, DelawareDover, DelawareThe city of Dover is the capital and second largest city in the U.S. state of Delaware. It is also the county seat of Kent County, and the principal city of the Dover, Delaware Metropolitan Statistical Area, which encompasses all of Kent County. It is located on the St. Jones River in the Delaware... - Dyess Air Force BaseDyess Air Force BaseDyess Air Force Base is a United States Air Force base located approximately southwest of Abilene, Texas.The host unit at Dyess is the 7th Bomb Wing assigned to the Air Combat Command Twelfth Air Force...
, Abilene, TexasAbilene, TexasAbilene is a city in Taylor and Jones counties in west central Texas. The population was 117,063 at the 2010 census. It is the principal city of the Abilene Metropolitan Statistical Area, which had a 2006 estimated population of 158,063. It is the county seat of Taylor County... - East Texas Regional AirportEast Texas Regional AirportEast Texas Regional Airport is a public airport located eight miles south of Longview, Texas. The airport has two intersecting runways and its IATA identifier "GGG" comes from its prior name , derived from its location in Gregg County, Texas.GGG is mostly used for general aviation and military...
, Longview, TexasLongview, TexasLongview is a city in Gregg and Harrison Counties in the U.S. state of Texas. As of the 2010 Census, the population was 80,455. Most of the city is located in Gregg County, of which it is the county seat; only a small part extends into the western part of neighboring Harrison County. It is... - Edwards Air Force BaseEdwards Air Force BaseEdwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...
, CaliforniaCaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... - Ellsworth Air Force BaseEllsworth Air Force BaseEllsworth Air Force Base is a United States Air Force base located approximately northeast of Rapid City, South Dakota just north of Box Elder, South Dakota....
, Rapid City, South DakotaRapid City, South DakotaRapid City is the second-largest city in the U.S. state of South Dakota, and the county seat of Pennington County. Named after Rapid Creek on which the city is established, it is set against the eastern slope of the Black Hills mountain range. The population was 67,956 as of the 2010 Census. Rapid... - Elmendorf Air Force BaseElmendorf Air Force BaseJoint Base Elmendorf-Richardson is a United States military facility adjacent to Anchorage, the largest city in Alaska. It is an amalgamation of the former United States Air Force Elmendorf Air Force Base and the United States Army Fort Richardson, which were merged in 2010.-Overview:The...
, Anchorage, AlaskaAnchorage, AlaskaAnchorage is a unified home rule municipality in the southcentral part of the U.S. state of Alaska. It is the northernmost major city in the United States... - Fort Huachuca, Arizona, Sierra Vista, AZ
- Francis S. Gabreski AirportFrancis S. Gabreski AirportFrancis S. Gabreski Airport is a county-owned, civil airport located north of the central business district of Westhampton Beach, in Suffolk County, Long Island, New York, United States. It is approximately east of New York City....
, Long Island, NY - Grant County International AirportGrant County International AirportGrant County International Airport is a public use airport located five nautical miles northwest of the central business district of Moses Lake, in Grant County, Washington, United States. It is owned by the Port of Moses Lake....
, Moses Lake, WA - Griffiss International Airport, Rome, NY
- Grissom Air Force Base, Kokomo, IndianaKokomo, IndianaKokomo is a city in and the county seat of Howard County, Indiana, United States, Indiana's 13th largest city. It is the principal city of the Kokomo, Indiana Metropolitan Statistical Area, which includes all of Howard and Tipton counties....
- Hickam Air Force BaseHickam Air Force BaseHickam Field, re-named Hickam Air Force Base in 1948, was a United States Air Force facility now part of Joint Base Pearl Harbor-Hickam, named in honor of aviation pioneer Lt Col Horace Meek Hickam.- History :...
, Honolulu, HawaiiHonolulu, HawaiiHonolulu is the capital and the most populous city of the U.S. state of Hawaii. Honolulu is the southernmost major U.S. city. Although the name "Honolulu" refers to the urban area on the southeastern shore of the island of Oahu, the city and county government are consolidated as the City and... - John F. Kennedy International AirportJohn F. Kennedy International AirportJohn F. Kennedy International Airport is an international airport located in the borough of Queens in New York City, about southeast of Lower Manhattan. It is the busiest international air passenger gateway to the United States, handling more international traffic than any other airport in North...
, NY, NY - Lehigh Valley International AirportLehigh Valley International AirportLehigh Valley International Airport , formerly Allentown-Bethlehem-Easton International Airport, is a public airport in Hanover Township, Lehigh County, Pennsylvania....
, Allentown, PA - Lincoln Airport, Lincoln, NebraskaLincoln, NebraskaThe City of Lincoln is the capital and the second-most populous city of the US state of Nebraska. Lincoln is also the county seat of Lancaster County and the home of the University of Nebraska. Lincoln's 2010 Census population was 258,379....
- Mountain Home Air Force BaseMountain Home Air Force BaseMountain Home Air Force Base is a United States Air Force installation located in southwestern Idaho, United States. The base is in Elmore County, 12 miles southwest of the city of Mountain Home, which is 40 miles southeast of Boise, via Interstate 84.The host unit at Mountain Home since 1972...
, Mountain Home, IdahoMountain Home, IdahoMountain Home is the largest city and county seat of Elmore County, Idaho. The population was 14,206 at the 2010 census. Mountain Home is the principal city of the Mountain Home, ID Micropolitan Statistical Area, which includes Elmore County.... - Orlando International AirportOrlando International AirportOrlando International Airport is a major international airport located southeast of the central business district of Orlando. It is the second busiest airport in Florida, after Miami International Airport...
, Orlando, FloridaOrlando, FloridaOrlando is a city in the central region of the U.S. state of Florida. It is the county seat of Orange County, and the center of the Greater Orlando metropolitan area. According to the 2010 US Census, the city had a population of 238,300, making Orlando the 79th largest city in the United States... - Otis Air National Guard BaseOtis Air National Guard BaseOtis Air National Guard Base is an Air National Guard installation located within the Massachusetts Military Reservation , a military training facility, located on the western portion of Cape Cod, in western Barnstable County, Massachusetts, United States...
, Falmouth, MassachusettsFalmouth, MassachusettsFalmouth is a town in Barnstable County, Massachusetts, United States; Barnstable County is coextensive with Cape Cod. The population was 31,531 at the 2010 census.... - Pease Air Force Base, Portsmouth, New HampshirePortsmouth, New HampshirePortsmouth is a city in Rockingham County, New Hampshire in the United States. It is the largest city but only the fourth-largest community in the county, with a population of 21,233 at the 2010 census...
- Plattsburgh Air Force BasePlattsburgh Air Force BasePlattsburgh Air Force Base is a former United States Air Force Strategic Air Command base covering 3,447 acres in the extreme northeast corner of New York, 20 miles south of the Canadian border...
, PlattsburghPlattsburgh (town), New YorkPlattsburgh is a town in Clinton County, New York, United States. The population was 11,870 at the 2010 census. The town is named after Zephaniah Platt, an early land owner.The Town of Plattsburgh borders the City of Plattsburgh...
, New YorkNew YorkNew York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east... - Portsmouth International Airport, Portsmouth, New HampshirePortsmouth, New HampshirePortsmouth is a city in Rockingham County, New Hampshire in the United States. It is the largest city but only the fourth-largest community in the county, with a population of 21,233 at the 2010 census...
- Stewart Air National Guard BaseStewart Air National Guard BaseStewart Air National Guard Base is the home of the 105th Airlift Wing , an Air Mobility Command -gained unit of the New York Air National Guard and "host" wing for the installation...
, Newburgh, New York - Westover Air Force Base, Springfield, MassachusettsSpringfield, MassachusettsSpringfield is the most populous city in Western New England, and the seat of Hampden County, Massachusetts, United States. Springfield sits on the eastern bank of the Connecticut River near its confluence with three rivers; the western Westfield River, the eastern Chicopee River, and the eastern...
- White Sands Space HarborWhite Sands Space HarborWhite Sands Space Harbor is the primary training area used by NASA for Space Shuttle pilots flying practice approaches and landings in the Shuttle Training Aircraft and T-38 Talon aircraft. Its runways, navigational aids, runway lighting, and control facilities also stand continuously ready as a...
, White Sands, New MexicoWhite Sands, New MexicoWhite Sands is a census-designated place in Doña Ana County, New Mexico, United States. The population was 1,323 at the 2000 census. It is part of the Las Cruces Metropolitan Statistical Area... - Wilmington International AirportWilmington International Airport-Other operations:As of August 2011, Wilmington International Airport has 134 aircraft that are based at the Airport. There are 100 single engine aircraft, 27 multi-engine aircraft, 7 jet engine aircraft, and 3 helicopters...
, Wilmington, North CarolinaWilmington, North CarolinaWilmington is a port city in and is the county seat of New Hanover County, North Carolina, United States. The population is 106,476 according to the 2010 Census, making it the eighth most populous city in the state of North Carolina... - Wright-Patterson Air Force BaseWright-Patterson Air Force BaseWright-Patterson Air Force Base is a United States Air Force base in Greene and Montgomery counties in the state of Ohio. It includes both Wright and Patterson Fields, which were originally Wilbur Wright Field and Fairfield Aviation General Supply Depot. Patterson Field is located approximately...
, Dayton, OhioDayton, OhioDayton is the 6th largest city in the U.S. state of Ohio and the county seat of Montgomery County, the fifth most populous county in the state. The population was 141,527 at the 2010 census. The Dayton Metropolitan Statistical Area had a population of 841,502 in the 2010 census...
Zaire (now the Democratic Republic of the Congo)
- N'djili Airport, KinshasaKinshasaKinshasa is the capital and largest city of the Democratic Republic of the Congo. The city is located on the Congo River....
(until 1997)
Other locations
In the event of an emergency deorbit that would bring the Orbiter down in an area not within range of a designated emergency landing site, the Orbiter is theoretically capable of landing on any paved runway that is at least 3 km (9,842.5 ft) long, which includes the majority of large commercial airports. In practice, a US or allied military airfield would probably be preferred for reasons of security arrangements and minimizing the disruption of commercial air traffic.Preferences
There is an order of preference for abort modes. ATO is the preferred abort option whenever possible. TAL is the preferred abort option if the vehicle has not yet reached a speed permitting the ATO option. AOA would only be used in the brief window between TAL and ATO options. RTLS results in the quickest landing of all abort options, but is considered the riskiest abort. Therefore it is selected only in cases where the developing emergency is so time-critical the other aborts aren't feasible, or in cases where the vehicle has insufficient energy to reach the other aborts.Unlike all previous U.S. manned launch vehicles, the shuttle never flew unmanned test flights. To provide an incremental non-orbital manned test, NASA considered making the first mission an RTLS abort. However, STS-1
STS-1
STS-1 was the first orbital flight of NASA's Space Shuttle program. Space Shuttle Columbia launched on 12 April 1981, and returned to Earth on 14 April, having orbited the Earth 37 times during the 54.5-hour mission. It was the first American manned space flight since the Apollo-Soyuz Test Project...
commander John Young declined, saying, "let's not practice Russian roulette
Russian roulette
Russian roulette is a potentially lethal game of chance in which participants place a single round in a revolver, spin the cylinder, place the muzzle against their head and pull the trigger...
."
Contingency aborts
Contingency aborts are designed to permit flight crew survival following more severe failures when an intact abort is not possible. A contingency abort would generally result in a ditch operation.Were the Orbiter unable to reach a runway, it could ditch in water, or could land on terrain other than a landing site. It would be unlikely for the flight crew still on board to survive. However, for ascent abort scenarios where controlled gliding flight is achievable, a bailout is possible. For more details, see "Post-Challenger abort enhancements" below.
In the two disasters, things went wrong so fast that little could be done. In the case of Challenger
STS-51-L
STS-51-L was the twenty-fifth flight of the American Space Shuttle program, which marked the first time an ordinary civilian, schoolteacher Christa McAuliffe, had flown aboard the Space Shuttle. The mission used Space Shuttle Challenger, which lifted off from the Launch Complex 39-B on 28 January...
, the Space Shuttle Solid Rocket Booster
Space Shuttle Solid Rocket Booster
The Space Shuttle Solid Rocket Boosters were the pair of large solid rockets used by the United States' NASA Space Shuttle during the first two minutes of powered flight. Together they provided about 83% of liftoff thrust for the Space Shuttle. They were located on either side of the rusty or...
s were still burning as they tore free from the rest of the stack, one likely impacting the external tank. The orbiter disintegrated almost instantly from aerodynamic stresses as the stack broke up. The Columbia disaster
Space Shuttle Columbia disaster
The Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members...
occurred high in the atmosphere during reentry. Even if the crew had been able to bail out, they would have been killed by the heat generated at hypersonic velocities.
Post-Challenger abort enhancements
Before the Challenger disasterSpace Shuttle Challenger disaster
The Space Shuttle Challenger disaster occurred on January 28, 1986, when Space Shuttle Challenger broke apart 73 seconds into its flight, leading to the deaths of its seven crew members. The spacecraft disintegrated over the Atlantic Ocean, off the coast of central Florida at 11:38 am EST...
during STS-51-L
STS-51-L
STS-51-L was the twenty-fifth flight of the American Space Shuttle program, which marked the first time an ordinary civilian, schoolteacher Christa McAuliffe, had flown aboard the Space Shuttle. The mission used Space Shuttle Challenger, which lifted off from the Launch Complex 39-B on 28 January...
, very limited ascent abort options existed. Failure of only a single SSME
Space Shuttle main engine
The RS-25, otherwise known as the Space Shuttle Main Engine , is a reusable liquid-fuel rocket engine built by Pratt & Whitney Rocketdyne for the Space Shuttle, running on liquid hydrogen and oxygen. Each Space Shuttle was propelled by three SSMEs mated to one powerhead...
was survivable prior to about 350 seconds into the ascent. Two or three failed SSMEs prior to that point would mean loss of crew and vehicle (LOCV), since no bailout option existed. Two or three failed SSMEs while the SRBs are firing would probably have overstressed the struts attaching the orbiter to the external tank, causing vehicle breakup. For that reason, a Return To Launch Site (RTLS) abort was not possible in the event of two or three failed SSMEs. Studies showed an ocean ditching was not survivable. Furthermore, the loss of a second or third SSME at almost any time during an RTLS abort would have caused a LOCV.
After the loss of Challenger in STS-51-L
STS-51-L
STS-51-L was the twenty-fifth flight of the American Space Shuttle program, which marked the first time an ordinary civilian, schoolteacher Christa McAuliffe, had flown aboard the Space Shuttle. The mission used Space Shuttle Challenger, which lifted off from the Launch Complex 39-B on 28 January...
, numerous abort enhancements were added. With those enhancements, the loss of two SSMEs is now survivable for the crew throughout the entire ascent, and the vehicle could survive and land for large portions of the ascent. Loss of three SSMEs is survivable for the crew for most of the ascent, although survival in the event of three failed SSMEs before T+90 seconds is questionable. However, it is conceivable that failure of three SSMEs just after liftoff might be survivable, since the SRBs provide enough thrust and steering authority to continue the ascent until a bailout or RTLS. The struts attaching the orbiter to the external tank were strengthened to better endure a multiple SSME failure.
A particular significant enhancement was bailout capability. This is not ejection as with a fighter plane, but an Inflight Crew Escape System (ICES). The vehicle is put in a stable glide on autopilot, the hatch is blown, and the crew slides out a pole to clear the orbiter's left wing. They would then parachute to earth or the sea. While this may at first appear only usable under rare conditions, there are many failure modes where reaching an emergency landing site is not possible yet the vehicle is still intact and under control. Before the Challenger disaster, this almost happened on STS-51-F
STS-51-F
STS-51-F was the nineteenth flight of NASA's Space Shuttle program, and the eighth flight of Space Shuttle Challenger...
, when a single SSME failed at about T+345 seconds. The orbiter in that case was also Challenger. A second SSME almost failed due to a spurious temperature reading; fortunately the engine shutdown was inhibited by a quick-thinking flight controller. If the second SSME failed within about 69 seconds of the first, there would have been insufficient energy to cross the Atlantic. Without bailout capability the entire crew would be lost. After the loss of Challenger, those types of failures have been made survivable. To facilitate high altitude bailouts, the crew now wears Advanced Crew Escape Suit
Advanced Crew Escape Suit
The Advanced Crew Escape Suit or "pumpkin suit", was a full pressure suit that began to be worn by Space Shuttle crews after STS-65, for the ascent and entry portions of flight. The suit is a direct descendant of the U.S...
s during ascent and descent. Before the Challenger disaster, crews for operational missions wore only fabric flight suits.
Another post-Challenger enhancement was the addition of East Coast Abort Landings (ECAL). High-inclination launches (including all ISS
ISS
The ISS is the International Space Station.ISS may also refer to:* I See Stars, an American electronic rock band* ISS A/S, a Danish service company* Idea Star Singer, a Malayalam music reality show by Asianet TV...
missions) can now reach an emergency runway on the East Coast of the United States under certain conditions.
An ECAL abort is similar to RTLS, but instead of landing at the Kennedy Space Center, the Orbiter would attempt to land at another site along the east coast of North America. Various emergency landing sites extend from South Carolina and Bermuda up into Newfoundland, Canada. ECAL is a contingency abort that is less desirable than an intact abort, primarily because there is so little time to choose the landing site and prepare for the Orbiter's arrival. The ECAL emergency sites are not as well equipped to accommodate an Orbiter landing.
Numerous other abort refinements were added, mainly involving improved software for managing vehicle energy in various abort scenarios. These enable a greater chance of reaching an emergency runway for various SSME failure scenarios.
Ejection escape systems
An ejection escape system, sometimes called a launch escape systemLaunch escape system
A Launch Escape System is a top-mounted rocket connected to the crew module of a crewed spacecraft and used to quickly separate the crew module from the rest of the rocket in case of emergency. Since the escape rockets are above the crew module, an LES typically uses separate nozzles which are...
, has been discussed many times for the shuttle. After the Challenger and Columbia losses, great interest was expressed in this. All previous US manned space vehicles had launch escape systems, although none were ever used.
Ejection seat
Modified Lockheed SR-71 ejection seats were installed on the first four shuttle flights (all two-man missions aboard Columbia) and removed afterward. Ejection seats were not further developed for the shuttle for several reasons:- Very difficult to eject seven crew members when three or four are on the middeck (roughly the center of the forward fuselageFuselageThe fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
), surrounded by substantial vehicle structure. - Limited ejection envelope. Ejection seats only work up to about 3,400 mph (2,692 knots) and 130,000 feet (39,624 m). That constitutes a very limited portion of the shuttle's operating envelope, about the first 100 seconds of the 510 seconds powered ascent.
- No help during Columbia-type reentryAtmospheric reentryAtmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line,...
accident. Ejecting during an atmospheric reentryAtmospheric reentryAtmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line,...
accident would be fatal due to the high temperatures and wind blast at high Mach speeds.
The Soviet shuttle Buran was planned to be fitted with the crew emergency escape system, which would have included K-36RB (K-36M-11F35) seats and the "Strizh" full-pressure suit, qualified for altitudes up to 30,000 m and speeds up to Mach 3. Buran flew only once in fully automated mode without a crew, thus the seats were never installed and were never tested in real human space flight.
Ejection capsule
An alternative to ejection seats is an escape crew capsuleEscape crew capsule
An escape crew capsule allows a pilot to escape from their craft while it is subjected to extreme conditions such as high speed or altitude...
or cabin escape system where the crew ejects in protective capsules, or the entire cabin is ejected. Such systems have been used on several military aircraft. The B-58 Hustler
B-58 Hustler
The Convair B-58 Hustler was the first operational supersonic jet bomber capable of Mach 2 flight. The aircraft was designed by Convair engineer Robert H. Widmer and developed for the United States Air Force for service in the Strategic Air Command during the 1960s...
and XB-70 Valkyrie
XB-70 Valkyrie
The North American Aviation XB-70 Valkyrie was the prototype version of the proposed B-70 nuclear-armed deep-penetration strategic bomber for the United States Air Force's Strategic Air Command...
used capsule ejection. The General Dynamics F-111
General Dynamics F-111
The General Dynamics F-111 "Aardvark" was a medium-range interdictor and tactical strike aircraft that also filled the roles of strategic bomber, reconnaissance, and electronic warfare in its various versions. Developed in the 1960s by General Dynamics, it first entered service in 1967 with the...
and early prototypes of the Rockwell B-1 bomber
B-1 Lancer
The Rockwell B-1 LancerThe name "Lancer" is only applied to the B-1B version, after the program was revived. is a four-engine variable-sweep wing strategic bomber used by the United States Air Force...
used cabin ejection.
Like ejection seats, capsule ejection for the shuttle would be difficult because no easy way exists to exit the vehicle. Several crewmembers sit in the middeck, surrounded by substantial vehicle structure.
Cabin ejection would work for a much larger portion of the flight envelope than ejection seats, as the crew would be protected from temperature, wind blast, and lack of oxygen or vacuum. In theory an ejection cabin could be designed to withstand reentry, although that would entail additional cost, weight and complexity. Cabin ejection was not pursued for several reasons:
- Major modifications required to shuttle, likely taking several years. During much of the period the vehicle would be unavailable.
- Cabin ejection systems are heavy, thus incurring a significant payload penalty.
- Cabin ejection systems are much more complex than ejection seats. They require devices to cut cables and conduits connecting the cabin and fuselage. The cabin must have aerodynamic stabilization devices to avoid tumbling after ejection. The large cabin weight mandates a very large parachute, with a more complex extraction sequence. Air bags must deploy beneath the cabin to cushion impact or provide flotation. To make on-the-pad ejections feasible, the separation rockets would have to be quite large. In short, many complex things must happen in a specific timed sequence for cabin ejection to be successful, and in a situation where the vehicle might be disintegrating. If the airframe twisted or warped, thus preventing cabin separation, or debris damaged the landing airbags, stabilization, or any other cabin system, the occupants would likely not survive.
- Added risk due to many large pyrotechnicExplosive materialAn explosive material, also called an explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure...
devices. Even if not needed, the many explosive devices needed to separate the cabin entail some risk of premature or uncommanded detonation. - Cabin ejection is much more difficult, expensive and risky to retrofit on a vehicle not initially designed for it. If the shuttle was initially designed with a cabin escape system, that might have been more feasible.
- Cabin/capsule ejection systems have a spotty success record, likely because of the complexity.
Space Shuttle Abort History
| Date | Orbiter | Mission | Type of Abort | Time of Abort | Description |
|---|---|---|---|---|---|
| 1984-06-26 | Discovery Space Shuttle Discovery Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011... |
STS-41-D STS-41-D STS-41-D was the first flight of NASA's Space Shuttle orbiter Discovery. It was the 12th mission of the Space Shuttle program, and was launched from Kennedy Space Center, Florida, on 30 August 1984... |
RSLS | T-3 seconds | Sluggish valve detected in Space shuttle main engine (SSME) #3. Discovery rolled back to VAB for replacement engine. |
| 1985-07-12 | Challenger Space Shuttle Challenger Space Shuttle Challenger was NASA's second Space Shuttle orbiter to be put into service, Columbia having been the first. The shuttle was built by Rockwell International's Space Transportation Systems Division in Downey, California... |
STS-51-F STS-51-F STS-51-F was the nineteenth flight of NASA's Space Shuttle program, and the eighth flight of Space Shuttle Challenger... |
RSLS | T-3 seconds | Coolant valve problem with SSME #2. Valve was replaced on launch pad. |
| 1985-07-29 | Challenger Space Shuttle Challenger Space Shuttle Challenger was NASA's second Space Shuttle orbiter to be put into service, Columbia having been the first. The shuttle was built by Rockwell International's Space Transportation Systems Division in Downey, California... |
STS-51-F STS-51-F STS-51-F was the nineteenth flight of NASA's Space Shuttle program, and the eighth flight of Space Shuttle Challenger... |
ATO | T+5 minutes, 45 seconds | Sensor problem shutdown SSME #1. Mission continued in lower than planned orbit. |
| 1993-03-22 | Columbia Space Shuttle Columbia Space Shuttle Columbia was the first spaceworthy Space Shuttle in NASA's orbital fleet. First launched on the STS-1 mission, the first of the Space Shuttle program, it completed 27 missions before being destroyed during re-entry on February 1, 2003 near the end of its 28th, STS-107. All seven crew... |
STS-55 STS-55 -Backup crew:-Mission parameters:*Mass:**Orbiter landing with payload: **Payload: *Perigee: *Apogee: *Inclination: 28.5°*Period: 90.7 min-Mission highlights:... |
RSLS | T-3 seconds | Problem with purge pressure readings in the oxidizer preburner on SSME #2. All engines replaced on pad. |
| 1993-08-12 | Discovery Space Shuttle Discovery Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011... |
STS-51 STS-51 STS-51 was a Space Shuttle Discovery mission that launched the Advanced Communications Technology Satellite ACTS in September 1993. The flight also featured the deployment and retrieval of the SPAS-ORFEUS satellite and its IMAX camera, which captured spectacular footage of Discovery in space... |
RSLS | T-3 seconds | Sensor that monitors flow of hydrogen fuel in SSME #2 failed. All engines replaced on launch pad. |
| 1994-08-18 | Endeavour Space Shuttle Endeavour Space Shuttle Endeavour is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States. Endeavour was the fifth and final spaceworthy NASA space shuttle to be built, constructed as a replacement for Challenger... |
STS-68 STS-68 STS-68 was a human spaceflight mission using that launched from Kennedy Space Center, Florida on 1994-09-30.-Crew:-Launch:Launch 30 September 1994 at 7:16:00.068 am EDT from Kennedy Space Center Launch Pad 39-A. The Launch window opened at 7:16 am EDT with a 2 hour 30 minute window. Orbiter... |
RSLS | T-1.9 seconds | Sensor detected higher than acceptable readings of the discharge temperature of the high pressure oxidizer turbopump in SSME #3. Endeavour rolled back to VAB for to replace all 3 engines. A test firing at Stennis Space Center John C. Stennis Space Center The John C. Stennis Space Center , located in Hancock County, Mississippi, at the Mississippi-Louisiana border, is NASA's largest rocket engine test facility.- History :... confirmed a drift in the fuel flow meter which resulted in a slower start in the engine which caused the higher temperatures. |
See also
- Apollo abort modesApollo abort modesDuring the launch of an Apollo spacecraft by the Saturn V rocket, the flight could be aborted to rescue the crew if the rocket failed catastrophically. Depending on how far into the flight the crew were, they would use different procedures or modes...
- Launch escape systemLaunch escape systemA Launch Escape System is a top-mounted rocket connected to the crew module of a crewed spacecraft and used to quickly separate the crew module from the rest of the rocket in case of emergency. Since the escape rockets are above the crew module, an LES typically uses separate nozzles which are...
- NASA Space Shuttle decisionNASA Space Shuttle decisionEven before the Apollo moon landing in 1969, in October 1968, NASA began early studies of space shuttle designs. The early studies were denoted "Phase A", and in June 1970, "Phase B", which were more detailed and specific. The primary intended use of the space shuttle was supporting the future...
- Orion abort modesOrion abort modesNASA's newest spacecraft, the Orion Crew Exploration Vehicle , which will replace the Space Shuttle after 2011, will be the first spacecraft since Project Apollo to utilize an escape system in the event of a launch abort, something the Shuttle had only for its first four orbital test flights in...
- Space Shuttle Challenger disasterSpace Shuttle Challenger disasterThe Space Shuttle Challenger disaster occurred on January 28, 1986, when Space Shuttle Challenger broke apart 73 seconds into its flight, leading to the deaths of its seven crew members. The spacecraft disintegrated over the Atlantic Ocean, off the coast of central Florida at 11:38 am EST...
- Space Shuttle Columbia disasterSpace Shuttle Columbia disasterThe Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members...
- Space Shuttle programSpace Shuttle programNASA's Space Shuttle program, officially called Space Transportation System , was the United States government's manned launch vehicle program from 1981 to 2011...