Mercury-Redstone 1
Encyclopedia
Mercury-Redstone 1 was the first Mercury-Redstone mission in the Mercury program
and the first attempt to launch a Mercury spacecraft
with the Mercury-Redstone
launch vehicle
. Intended to be an unmanned sub-orbital flight, it was launched on November 21, 1960 from Cape Canaveral
, Florida
. The launch failed in a peculiar fashion which has been referred to as the "four-inch flight".
for the sub-orbital Mercury mission. It would also qualify the spacecraft's automated flight control and recovery systems, as well as the launch, tracking, and recovery operations on the ground. The mission would also test the Mercury-Redstone's automatic inflight abort sensing system, which would be operating in "open-loop" mode. This meant that the abort sensing system could report a condition requiring an abort, but it would be unable to actually trigger an abort itself. Since the flight did not have a living passenger, this would not pose a safety problem, and it would prevent a faulty abort signal from prematurely ending the flight.
The mission used Mercury spacecraft #2 together with Redstone MR-1; its launch location was Cape Canaveral Air Force Station
's Launch Complex 5
. An early launch attempt on November 7 was canceled due to last-minute problems with the capsule, so launching was rescheduled for November 21.
On that day, following a normal countdown, the Mercury-Redstone's engine ignited on schedule at 9:00 a.m. Eastern Standard Time
(14:00 GMT). However, the engine shut down immediately after lift-off from the launch pad. The rocket only rose about 4 inches (10.2 cm) before settling back onto the pad. It wobbled slightly, but stayed upright and did not explode. An odd series of events then took place.
Immediately after the Redstone's engine shut down, the Mercury capsule's escape rocket
jettisoned itself, leaving the capsule attached to the rocket. The escape rocket rose to an altitude of 4000 feet (1,219.2 m) and landed about 400 yards (365.8 m) away. Three seconds after the escape rocket fired, the capsule deployed its drogue parachute
; it then deployed the main and reserve parachutes, ejecting the radio antenna fairing in the process.
In the end, all that had been launched was the escape rocket. Meanwhile, a fully fueled, slightly wrinkled Redstone and its Mercury capsule sat on the launch pad, both with full batteries and live pyrotechnics. Among these pyrotechnics were the capsule's retrorocket
s and the Redstone's self-destruct
system, which was still active. Furthermore, the capsule's main and reserve parachutes were hanging down the side of the rocket, threatening to tip it over if they caught enough wind. Fortunately, the weather conditions were favorable. Technicians had to wait until the next morning, when the flight batteries in the rocket and capsule had run down and the Redstone's liquid oxygen
had boiled off, before they could work on the rocket and render it safe.
. Both cables were plugged into the rocket at the bottom edge of one of its tail fins and would separate at liftoff. The control cable was supposed to separate first, followed by the power cable. However, for this launch, a control cable for the military Redstone missile had been substituted for the shorter cable designed for Mercury-Redstone. This control cable had been clamped to compensate for its greater length. But when the vehicle lifted off, the clamping did not work as planned, and the control cable separated about 29 milliseconds after the power cable did.
During this brief interval, the lack of electrical grounding caused a substantial current to flow through an electrical relay
which was supposed to trigger normal engine cut-off at the end of powered flight. This relay tripped, causing the Redstone to shut off its engine and send a "normal cut-off" signal to the capsule, which jettisoned its escape rocket as it was supposed to. However, the capsule did not separate from the rocket as it normally would have. The capsule was designed to suspend its separation until the vehicle's acceleration had almost ceased, so that the capsule would not be hit by its own launch vehicle. Because the acceleration sensors in the capsule detected a constant acceleration of 1 g
, capsule separation was disabled.
The jettison of the escape rocket activated the capsule's parachute recovery system. Since the altitude was below 10000 feet (3,048 m), this system was triggered by its atmospheric pressure sensors and followed its usual sequence, with the drogue parachute deploying first, followed by the main parachute. But because the main parachute was not supporting the capsule's weight, the parachute system did not detect any load on this chute, so it acted as if the chute had failed and deployed the reserve parachute.
Since the Redstone's automatic inflight abort sensing system was running in open-loop mode, the engine shutdown did not trigger an abort. However, the system did report an abort condition, so it did function properly.
in Huntsville
, Alabama
, and was held in reserve. A new mission was scheduled, Mercury-Redstone 1A
(MR-1A), which would use a new Mercury-Redstone rocket, numbered MR-3. MR-1's Mercury spacecraft, #2, was undamaged, so it was reused for MR-1A, together with the escape rocket from spacecraft #8 and the antenna fairing from spacecraft #10.
To prevent a failure like MR-1 from happening again, subsequent Mercury-Redstones added a grounding strap about 12 inches (30.5 cm) long to electrically connect the rocket to the launch pad. This strap was designed to separate from the rocket well after all other electrical connections to the ground had been severed.
Mercury engineers were also concerned that MR-1's failure had allowed a "normal cutoff" signal to reach the capsule and trigger the premature jettisoning of the escape rocket, since in an actual emergency this might remove the only escape mechanism for the astronaut. To prevent this, the Mercury-Redstone was altered so that it could not send a "normal cutoff" signal to the capsule until 129.5 seconds after liftoff, about 10 seconds before the expected time of the Redstone's actual engine cutoff.
MR-1 was never used for another mission after its return to Huntsville. It was eventually put on display at the Space Orientation Center of Marshall Space Flight Center.
, Moffett Federal Airfield
, near Mountain View
, California
. A Mercury-Redstone rocket is currently on display at the U.S. Space & Rocket Center in Huntsville among other locations.
Mercury program
Mercury Program might refer to:*the first successful American manned spaceflight program, Project Mercury*an American post-rock band, The Mercury Program...
and the first attempt to launch a Mercury spacecraft
Project Mercury
In January 1960 NASA awarded Western Electric Company a contract for the Mercury tracking network. The value of the contract was over $33 million. Also in January, McDonnell delivered the first production-type Mercury spacecraft, less than a year after award of the formal contract. On February 12,...
with the Mercury-Redstone
Mercury-Redstone Launch Vehicle
The Mercury-Redstone Launch Vehicle, designed for NASA's Project Mercury, was the first American manned space booster. It was used for six sub-orbital Mercury flights from 1960–61; culminating with the launch of the first, and 11 weeks later, the second American in space.A member of the...
launch vehicle
Launch vehicle
In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
. Intended to be an unmanned sub-orbital flight, it was launched on November 21, 1960 from Cape Canaveral
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...
, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. The launch failed in a peculiar fashion which has been referred to as the "four-inch flight".
Mission background and launch failure
The purpose of the MR-1 mission was to qualify the Mercury spacecraft and the Mercury-Redstone launch vehicleLaunch vehicle
In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from the Earth's surface into outer space. A launch system includes the launch vehicle, the launch pad and other infrastructure....
for the sub-orbital Mercury mission. It would also qualify the spacecraft's automated flight control and recovery systems, as well as the launch, tracking, and recovery operations on the ground. The mission would also test the Mercury-Redstone's automatic inflight abort sensing system, which would be operating in "open-loop" mode. This meant that the abort sensing system could report a condition requiring an abort, but it would be unable to actually trigger an abort itself. Since the flight did not have a living passenger, this would not pose a safety problem, and it would prevent a faulty abort signal from prematurely ending the flight.
The mission used Mercury spacecraft #2 together with Redstone MR-1; its launch location was Cape Canaveral Air Force Station
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...
's Launch Complex 5
Cape Canaveral Air Force Station Launch Complex 5
Launch Complex 5 was a launch site at Cape Canaveral Air Force Station, Florida used for various Redstone and Jupiter launches.It is most well known as the launch site for NASA's 1961 suborbital Mercury-Redstone 3 flight, which made Alan Shepard the first American in space. It was also the launch...
. An early launch attempt on November 7 was canceled due to last-minute problems with the capsule, so launching was rescheduled for November 21.
On that day, following a normal countdown, the Mercury-Redstone's engine ignited on schedule at 9:00 a.m. Eastern Standard Time
Eastern Standard Time
Eastern Standard Time may refer to:*North American Eastern Time Zone, UTC-5*Australian Eastern Standard Time, UTC+10*An album by Hip Hop group Kooley High...
(14:00 GMT). However, the engine shut down immediately after lift-off from the launch pad. The rocket only rose about 4 inches (10.2 cm) before settling back onto the pad. It wobbled slightly, but stayed upright and did not explode. An odd series of events then took place.
Immediately after the Redstone's engine shut down, the Mercury capsule's escape rocket
Launch 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...
jettisoned itself, leaving the capsule attached to the rocket. The escape rocket rose to an altitude of 4000 feet (1,219.2 m) and landed about 400 yards (365.8 m) away. Three seconds after the escape rocket fired, the capsule deployed its drogue parachute
Drogue parachute
A drogue parachute is a parachute designed to be deployed from a rapidly moving object in order to slow the object, or to provide control and stability, or as a pilot parachute to deploy a larger parachute...
; it then deployed the main and reserve parachutes, ejecting the radio antenna fairing in the process.
In the end, all that had been launched was the escape rocket. Meanwhile, a fully fueled, slightly wrinkled Redstone and its Mercury capsule sat on the launch pad, both with full batteries and live pyrotechnics. Among these pyrotechnics were the capsule's retrorocket
Retrorocket
A retrorocket is a rocket engine providing thrust opposing the motion of a spacecraft, thereby causing it to decelerate.-History:...
s and the Redstone's self-destruct
Self-destruct
A self-destruct is a mechanism which causes a device to destroy itself under a predefined set of circumstances.Self-destruct mechanisms are also found on devices and systems where malfunction could endanger large numbers of people...
system, which was still active. Furthermore, the capsule's main and reserve parachutes were hanging down the side of the rocket, threatening to tip it over if they caught enough wind. Fortunately, the weather conditions were favorable. Technicians had to wait until the next morning, when the flight batteries in the rocket and capsule had run down and the Redstone's liquid oxygen
Liquid oxygen
Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...
had boiled off, before they could work on the rocket and render it safe.
Causes of the failure
Investigation revealed that the Redstone's engine shutdown was caused by two of its electrical cables separating in the wrong order. These cables were a control cable, which provided various control signals, and a power cable, which provided electrical power and groundingGround (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
. Both cables were plugged into the rocket at the bottom edge of one of its tail fins and would separate at liftoff. The control cable was supposed to separate first, followed by the power cable. However, for this launch, a control cable for the military Redstone missile had been substituted for the shorter cable designed for Mercury-Redstone. This control cable had been clamped to compensate for its greater length. But when the vehicle lifted off, the clamping did not work as planned, and the control cable separated about 29 milliseconds after the power cable did.
During this brief interval, the lack of electrical grounding caused a substantial current to flow through an electrical relay
Relay
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...
which was supposed to trigger normal engine cut-off at the end of powered flight. This relay tripped, causing the Redstone to shut off its engine and send a "normal cut-off" signal to the capsule, which jettisoned its escape rocket as it was supposed to. However, the capsule did not separate from the rocket as it normally would have. The capsule was designed to suspend its separation until the vehicle's acceleration had almost ceased, so that the capsule would not be hit by its own launch vehicle. Because the acceleration sensors in the capsule detected a constant acceleration of 1 g
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
, capsule separation was disabled.
The jettison of the escape rocket activated the capsule's parachute recovery system. Since the altitude was below 10000 feet (3,048 m), this system was triggered by its atmospheric pressure sensors and followed its usual sequence, with the drogue parachute deploying first, followed by the main parachute. But because the main parachute was not supporting the capsule's weight, the parachute system did not detect any load on this chute, so it acted as if the chute had failed and deployed the reserve parachute.
Since the Redstone's automatic inflight abort sensing system was running in open-loop mode, the engine shutdown did not trigger an abort. However, the system did report an abort condition, so it did function properly.
Aftermath
The Redstone had suffered some minor damage from falling back on the pad, but it could still be used after refurbishment, so it was returned to Marshall Space Flight CenterMarshall Space Flight Center
The George C. Marshall Space Flight Center is the U.S. government's civilian rocketry and spacecraft propulsion research center. The largest center of NASA, MSFC's first mission was developing the Saturn launch vehicles for the Apollo moon program...
in Huntsville
Huntsville, Alabama
Huntsville is a city located primarily in Madison County in the central part of the far northern region of the U.S. state of Alabama. Huntsville is the county seat of Madison County. The city extends west into neighboring Limestone County. Huntsville's population was 180,105 as of the 2010 Census....
, Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
, and was held in reserve. A new mission was scheduled, Mercury-Redstone 1A
Mercury-Redstone 1A
Mercury-Redstone 1A was launched on December 19, 1960 from LC-5 at Cape Canaveral, Florida. The mission objectives of this unmanned suborbital flight were to qualify the spacecraft for space flight and qualify the system for an upcoming primate suborbital flight. The spacecraft tested its...
(MR-1A), which would use a new Mercury-Redstone rocket, numbered MR-3. MR-1's Mercury spacecraft, #2, was undamaged, so it was reused for MR-1A, together with the escape rocket from spacecraft #8 and the antenna fairing from spacecraft #10.
To prevent a failure like MR-1 from happening again, subsequent Mercury-Redstones added a grounding strap about 12 inches (30.5 cm) long to electrically connect the rocket to the launch pad. This strap was designed to separate from the rocket well after all other electrical connections to the ground had been severed.
Mercury engineers were also concerned that MR-1's failure had allowed a "normal cutoff" signal to reach the capsule and trigger the premature jettisoning of the escape rocket, since in an actual emergency this might remove the only escape mechanism for the astronaut. To prevent this, the Mercury-Redstone was altered so that it could not send a "normal cutoff" signal to the capsule until 129.5 seconds after liftoff, about 10 seconds before the expected time of the Redstone's actual engine cutoff.
MR-1 was never used for another mission after its return to Huntsville. It was eventually put on display at the Space Orientation Center of Marshall Space Flight Center.
Current location
Mercury spacecraft #2, used in both the Mercury-Redstone 1 and Mercury-Redstone 1A missions, is currently displayed at the Exploration Center at NASA Ames Research CenterNASA Ames Research Center
The Ames Research Center , is one of the United States of America's National Aeronautics and Space Administration 10 major field centers.The centre is located in Moffett Field in California's Silicon Valley, near the high-tech companies, entrepreneurial ventures, universities, and other...
, Moffett Federal Airfield
Moffett Federal Airfield
Moffett Federal Airfield , also known as Moffett Field, is a joint civil-military airport located between northern Mountain View and northern Sunnyvale, California, USA. The airport is near the south end of San Francisco Bay, northwest of San Jose. Formerly a United States Navy facility, the former...
, near Mountain View
Mountain View, California
-Downtown:Mountain View has a pedestrian-friendly downtown centered on Castro Street. The downtown area consists of the seven blocks of Castro Street from the Downtown Mountain View Station transit center in the north to the intersection with El Camino Real in the south...
, California
California
California 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...
. A Mercury-Redstone rocket is currently on display at the U.S. Space & Rocket Center in Huntsville among other locations.
External links
- A series of photos from GoogleGoogleGoogle Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...
's LIFE magazine photo archive, showing MR-1 jettisoning the escape rocket and deploying the drogue chute: http://images.google.com/hosted/life/l?imgurl=a12d228d52b43248, http://images.google.com/hosted/life/l?imgurl=18413a2cd6863cf1, http://images.google.com/hosted/life/l?imgurl=26ffd5921e018e26, http://images.google.com/hosted/life/l?imgurl=307d8cc6fb56b16e, http://images.google.com/hosted/life/l?imgurl=11bdb5ddd4e94ebc, http://images.google.com/hosted/life/l?imgurl=c302e245b7e00658. - Mercury spacecraft #2 display page on "A Field Guide to American Spacecraft" website.
- YouTube video of Mercury-Redstone 1 mishap