Mercury-Atlas 6
Encyclopedia
Mercury-Atlas 6 was a human spaceflight
mission conducted by NASA
, the space agency of the United States
. As part of Project Mercury
, MA-6 was the successful first attempt by NASA to place an astronaut into orbit
. The MA-6 mission was launched February 20, 1962. It made three orbits of the Earth, piloted by astronaut John Glenn
, who became the first American to orbit the Earth. The event was named an IEEE Milestone in 2011.
The Mercury spacecraft, named Friendship 7, was carried to orbit by an Atlas LV-3B
launch vehicle lifting off from Launch Complex 14
at Cape Canaveral
, Florida
. After four hours and 56 minutes in flight the spacecraft re-entered
the Earth's atmosphere, splashed down in the Atlantic Ocean
and was safely taken aboard the USS Noa
.
.
The Mercury 6 launch vehicle, Atlas #109-D, arrived at Cape Canaveral the evening of November 30, 1961. NASA had wanted to launch Mercury 6 in 1961 (hoping to orbit an astronaut in the same calendar year as the Soviets did), but by early December it was apparent that the mission hardware would not be ready for launch until early 1962.
Mercury spacecraft #13 began taking form on McDonnell's St. Louis, Missouri assembly line in May 1960. It was chosen for the MA-6 mission in October, 1960 and delivered to Cape Canaveral on August 27, 1961. Mercury spacecraft #13 and Atlas #109-D were stacked on the pad at Launch Complex 14 on January 2, 1962.
On January 27, 1962, John Glenn was onboard Mercury 6 and ready to launch, when, at T-20 minutes, the flight director called off the launch because of heavy overcast. The cloud cover would have prevented the necessary photo coverage of the launch. The launch was postponed until February 1, 1962.
When technicians began to fuel the Atlas on January 30, they discovered a fuel leak had soaked an internal insulation blanket between the fuel and oxidizer tanks of the rocket. This caused a two week delay while necessary repairs were made. On February 15, the launch was again postponed due to weather. Finally on February 19, the weather started to break. It appeared that February 20, 1962 would be a favorable day to attempt a launch.
At 14:47 UTC, after two hours and 17 minutes of holds and three hours and 44 minutes after Glenn entered Friendship 7, engineer T.J. O'Malley
pressed the button in the blockhouse launching the spacecraft. At liftoff Glenn's pulse rate climbed to 110.
Thirty seconds after liftoff the General Electric-Burroughs guidance system locked onto a radio transponder in the booster to guide the vehicle to orbit. As the Atlas and Friendship 7 passed through Max Q
Glenn reported, "It's a little bumpy about here." After Max Q the flight smoothed out. At two minutes and 14 seconds after launch, the booster engines cut off and dropped away. Then at two minutes and twenty-four seconds, the escape tower
was jettisoned, right on schedule.
After the tower was jettisoned, the Atlas and spacecraft pitched over still further, giving Glenn his first view of the horizon. He described the view as "a beautiful sight, looking eastward across the Atlantic." Vibration increased as the last of the fuel supply was used up. At sustainer engine cut-off it was found that the Atlas had accelerated the capsule to a speed only 7 ft/s (2 m/s) below nominal. At 14:52 UTC, Friendship 7 was in orbit. Glenn received word that the Atlas had boosted the MA-6 into a trajectory that would stay up for at least seven orbits. Meanwhile, computers at the Goddard Space Flight Center
in Maryland indicated that the MA-6 orbital parameters appeared good enough for almost 100 orbits.
When the posigrade rockets fired and separated the capsule from the booster, the five-second rate-damping operation started two and a half seconds late. This caused a substantial roll error as the capsule began its turnaround. The automatic attitude control system took 38 seconds to place the Friendship 7 into its proper orbital attitude. The turnaround maneuver used 5.4 pounds (2.4 kg) of fuel from a total supply of 60.4 pounds (27.4 kg)
The spacecraft then settled into orbital flight with a velocity of 17,544 mph (7,843 m/s).
Friendship 7 began its first orbit with all systems go. It crossed the Atlantic and passed over the Canary Islands
. Controllers there reported all capsule systems in perfect working order. Looking at the African coastline, and later the interior over Kano
, Nigeria
, Glenn told the tracking station team that he could see a dust storm. Kano flight communicators replied that the winds had been quite heavy for the past week.
Over Kano, Glenn took control of the spacecraft and started a major yaw adjustment. He allowed the spacecraft to continue the yaw maneuver until it was facing into its flight path. Glenn noticed that the attitude indicators disagreed with what he observed were the true spacecraft attitudes. Even with the incorrect instrument readouts, he was pleased to be facing forward instead of backward on his orbital path.
Over the Indian Ocean
, Glenn observed his first sunset from orbit. He described the moment of twilight as "beautiful." The sky in space was very black, he said, with a thin band of blue along the horizon. He said sun set fast, but not as quickly as he had expected. For five or six minutes there was a slow reduction in light intensity. Brilliant orange and blue layers spread out 45 to 60 degrees on either side of the sun, tapering gradually toward the horizon. Clouds prevented him from seeing a mortar
flare fired by the Indian Ocean tracking ship as part of a pilot observation experiment.
Continuing his journey on the night side of Earth, nearing the Australia
n coastline, Glenn made star, weather, and landmark observations. He looked for but failed to see the dim light phenomenon known as the zodiacal light
; his eyes had insufficient time to adapt to the darkness.
The spacecraft came into radio range of Muchea
, Australia. At the Mercury Tracking Station there, Gordon Cooper was the capsule communicator. Glenn reported that he felt fine and had no problems. He saw a very bright light and what appeared to be the outline of a city. Cooper said that he probably was looking at the lights of Perth
and its satellite town of Rockingham
. This turned out to be correct; many people in Perth turned on their lights so as to be visible to Glenn as he passed over. "That sure was a short day," he excitedly told Cooper. "That was about the shortest day I've ever run into."
The spacecraft moved across Australia and across the Pacific to Canton Island. Glenn experienced a short 45 minute night and prepared the periscope for viewing his first sunrise from orbit. As the sun rose over the island, he saw thousands of "little specks, brilliant specks, floating around outside the capsule"; he momentarily felt that the spacecraft was tumbling or that he was looking into a star field. A quick hard look out of the spacecraft window corrected the illusion and Glenn was sure that the "fireflies", as he called them, were streaming past his spacecraft from ahead. They seemed to flow by slowly but did not seem to be coming from any part of the spacecraft, and they disappeared as Friendship 7 moved into brighter sunlight. It was later determined that they were probably small ice crystals venting from onboard spacecraft systems.
I am in a big mass of some very small particles, they're brilliantly lit up like they're luminescent. I never saw anything like it. They round a little: they're coming by the capsule and they look like little stars. A whole shower of them coming by. They swirl around the capsule and go in front of the window and they're all brilliantly lighted.John Glenn started banging the capsule wall and watched the "fireflies" come off,just as Alan Shepard did.
As the spacecraft crossed the Kauai, Hawaii tracking station, Glenn noticed a lot of interference on the HF radio band. As he crossed the Pacific coast of North America, the tracking station at Guaymas
, Mexico
, informed Mercury Control in Florida that a yaw thruster was causing attitude control problems. Glenn later recalled, this problem "was to stick with me for the rest of the flight."
Glenn noticed the control problem when the automatic stabilization and control system allowed the spacecraft to drift about a degree and a half per second to the right. Glenn switched control to manual-proportional control mode and moved Friendship 7 back to the proper attitude. He tried different control modes to see which used the least fuel to maintain attitude. The manual fly-by-wire combination used the least fuel. After about twenty minutes the yaw thruster began working again and Glenn switched back to the automatic control system. It worked for a short time and then began having problems again, this time with the opposite yaw thruster. He then switched back to the manual fly-by-wire system and flew the spacecraft in that mode for the remainder of the flight.
at the start of its second orbit, a flight controller noticed that "Segment 51", a sensor providing data on the spacecraft landing system, was giving a strange reading. According to the reading, the heat shield and landing bag were no longer locked in position. If this were the case, the heat shield was only being held against the spacecraft by the straps of the retro package. Mercury Control ordered all tracking sites to monitor "Segment 51" closely and advise Glenn that the landing-bag deploy switch should be in the "off" position.
Glenn was not immediately aware of the problem, but he became suspicious when site after site asked him to make sure that the landing-bag deploy switch was off. Meanwhile Friendship 7 was crossing the Atlantic for the second time. Glenn was busy manually keeping the spacecraft attitude correct and also trying to accomplish as many of the flight plan tasks as he could.
Crossing over the Canary Islands, Glenn observed that the "fireflies" outside the spacecraft had no connection with gas from the reaction control jets. His suit temperature felt too warm, but he didn't take time to adjust it. The Kano, Nigeria and Zanzibar
sites suddenly noticed a 12 percent drop in the spacecraft secondary oxygen supply.
During his second pass over the Indian Ocean, Glenn found that the Indian Ocean tracking ship was in heavy weather. The tracking station had planned to release balloons for a pilot observation experiment, but instead the ship fired star-shell parachute flares as Friendship 7 passed overhead. Glenn was able to observe the flashes of lightning from storms in the area but was unable to see the flares.
The temperature in Glenn's spacesuit was too warm. It had been since he passed over the Canary Islands, earlier in the second orbit. As he crossed the Indian Ocean he tried to adjust the suit temperature. As he approached Woomera, Australia, a signal light came on warning him of excess cabin humidity. For the rest of the flight Glenn had to carefully balance suit cooling against the cabin humidity.
While he was still over Australia, another warning light came on, indicating that the fuel supply for the automatic control system was down to 62 percent. Mercury Control recommended that Glenn let the spacecraft attitude drift to conserve fuel.
There were no more problems for Friendship 7 during the remainder of the second orbit. Glenn continued to manually control the spacecraft attitude, not allowing it to drift too far out of alignment. In doing so, he consumed more fuel than a functioning automatic system would have used. Fuel consumption was 6 pounds (2.7 kg) from the automatic tank and 11.8 pounds (5.4 kg) from the manual tank, during the second orbit. This amounted to almost 30 percent of the total fuel supply.
. Glenn asked Cooper to notify General Shoup, Commandant of the Marine Corps, that three orbits should meet the minimum monthly requirement of four hours' flying time. He also asked to be certified as eligible for his regular flight pay.
During Glenn's orbits, Mercury Control had been monitoring the problem with "Segment 51". The Hawaiian tracking station asked Glenn to toggle the landing bag deploy switch into the automatic position. If a light came on, reentry should take place while retaining the retro pack. Given the earlier questions about the landing bag switch, Glenn realized there must be a possible problem with a loose heat shield. The test was run but no light appeared. Glenn also reported there were no bumping noises during spacecraft maneuvers.
Mercury Control was still undecided on the course of action to take. Some controllers thought the retrorocket
pack should be jettisoned after retrofire, while other controllers thought the retro pack should be retained, as added assurance that the heat shield would stay in place. Flight Director Chris Kraft and Mission Director Walter C. Williams, decided to keep the retro pack in place during reentry. Walter Schirra, the California communicator at Point Arguello, relayed the instructions to Glenn: the retro pack should be retained until the spacecraft was over the Texas tracking station. After the mission was over, the "Segment 51" warning light problem was later determined to be a faulty sensor switch, meaning that the heat shield and landing bag were in fact secure during reentry.
Glenn was now preparing for reentry. Retaining the retro package meant he would have to retract the periscope manually. He would also have to activate the 0.05-g sequence by pushing the override switch. Friendship 7 neared the California coast. It had been four hours and 33 minutes since launch. The spacecraft was maneuvered into retrofire attitude and the first retrorocket fired. "Boy, feels like I'm going halfway back to Hawaii," Glenn radioed. The second and then the third retros fired at five second intervals. The spacecraft attitude was steady during retrofire. Six minutes after retrofire; Glenn maneuvered the spacecraft into a 14 degree nose up, pitch attitude for reentry.
Friendship 7 lost altitude in its reentry glide over the continental United States, and headed toward splashdown in the Atlantic. The Texas tracking station told Glenn to retain the retro pack until the accelerometer read 1.5 g (14.7 m/s²). Glenn reported as he crossed Cape Canaveral he had been controlling the spacecraft manually and would use the fly-by–wire mode as a backup. Mercury Control then gave him the 0.05 g (0.49 m/s²) mark, and he pressed the override button. About the same time, Glenn heard noises that sounded like "small things brushing against the capsule." "That's a real fireball outside," he radioed Mercury Control. A strap from the retro package broke partially loose and hung over the spacecraft window as it was consumed in the reentry plasma stream. The spacecraft control system was working well but the manual fuel supply was down to 15 percent. The peak of reentry deceleration was still to come. Glenn switched to fly-by-wire and the automatic tank supply. This combination had more available fuel.
The spacecraft now experienced peak reentry heating. Glenn later reported, "I thought the retro pack had jettisoned and saw chunks coming off and flying by the window." He feared the chunks were pieces of his heatshield that might be disintegrating. The chunks were pieces of the retro package breaking up in the reentry fireball.
After passing the peak g region, the Friendship 7 began oscillating severely. The astronaut could not control the ship manually. The spacecraft was oscillating past 10 degrees on both sides of the vertical zero-degree point. "I felt like a falling leaf," Glenn later said. He activated the auxiliary damping system, this helped stabilize the large yaw and roll rates. Fuel in the automatic tanks was getting low. Glenn wondered if the spacecraft would retain stability until it was low enough to deploy the drogue parachute
.
The automatic fuel supply ran out at 1 minute and 51 seconds, and manual fuel ran out at 51 seconds, before drogue chute deployment. The oscillations resumed, at 35,000 feet (10 km) Glenn decided to deploy the drogue chute manually to regain attitude stability. Just before he reached the switch, the drogue chute opened automatically at 28,000 feet (8.5 km) instead of the programmed 21,000 feet (6.4 km). The spacecraft regained stability and Glenn reported, "everything was in good shape."
At 17,000 feet (5 km) the periscope opened and was available for the astronaut to use. Glenn tried to look out the overhead window instead, but it was coated with so much smoke and film that he could see very little. The spacecraft continued to descend on the drogue chute. The antenna section jettisoned and the main chute deployed and opened to its full diameter. Mercury Control reminded Glenn to manually deploy the landing bag. He toggled the switch and the green light confirmation came on. A "clunk" could be heard as the heat shield and landing bag dropped into place, four feet (1.2 m) below the capsule.
, a destroyer code-named Steelhead, had spotted the spacecraft when it was descending on its parachute. The destroyer was about six miles (10 km) away when it radioed Glenn that it would reach him shortly. The Noa came alongside Friendship 7 seventeen minutes later.
One crewman cleared the spacecraft antenna and another crewman attached a line to hoist Friendship 7 aboard. After being pulled from the water the spacecraft bumped against the side of the destroyer. Once Friendship 7 was on deck, Glenn intended to leave the capsule through the upper hatch, but it was too hot in the spacecraft and Glenn decided to blow the side hatch instead. He told the ship's crew to stand clear and hit the hatch detonator plunger with the back of his hand. The detonator plunger recoiled, and slightly cut the astronaut's knuckles through his glove. With a loud bang, the hatch was off. A smiling John Glenn got out of Friendship 7 and stood on the deck of the Noa. His first words were, "It was hot in there."
The astronaut and spacecraft came through the mission in good shape.
, Washington D.C. Mercury spacecraft #13 Friendship 7 display page on A Field Guide to American Spacecraft website.
On February 21, 1962, a metal fragment was recovered on a farm in South Africa. It was identified as coming from the MA-6 Atlas launch vehicle by numbers stamped on it. The fragment had landed on the farm after about eight hours in orbit.
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....
mission conducted by NASA
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...
, the space agency of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. As part of Project Mercury
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,...
, MA-6 was the successful first attempt by NASA to place an astronaut into orbit
Orbital spaceflight
An orbital spaceflight is a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit. To do this around the Earth, it must be on a free trajectory which has an altitude at perigee above...
. The MA-6 mission was launched February 20, 1962. It made three orbits of the Earth, piloted by astronaut John Glenn
John Glenn
John Herschel Glenn, Jr. is a former United States Marine Corps pilot, astronaut, and United States senator who was the first American to orbit the Earth and the third American in space. Glenn was a Marine Corps fighter pilot before joining NASA's Mercury program as a member of NASA's original...
, who became the first American to orbit the Earth. The event was named an IEEE Milestone in 2011.
The Mercury spacecraft, named Friendship 7, was carried to orbit by an Atlas LV-3B
Atlas LV-3B
The Atlas LV-3B, Atlas D Mercury Launch Vehicle or Mercury-Atlas Launch Vehicle, was a man-rated expendable launch system used as part of the United States Project Mercury to send astronauts into low Earth orbit. It was derived from the SM-65D Atlas missile, and was a member of the Atlas family of...
launch vehicle lifting off from Launch Complex 14
Cape Canaveral Air Force Station Launch Complex 14
Launch Complex 14 is a launch site at Cape Canaveral Air Force Station, Florida. LC-14 was used for various manned and unmanned Atlas launches, including the Friendship 7 flight aboard which John Glenn became the first American to orbit the Earth....
at 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...
. After four hours and 56 minutes in flight the spacecraft re-entered
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,...
the Earth's atmosphere, splashed down in the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and was safely taken aboard the USS Noa
USS Noa (DD-841)
USS Noa was a of the United States Navy, the second Navy ship named for Midshipman Loveman Noa .Noa was laid down by the Bath Iron Works, Bath, Maine, on 26 March 1945; launched on 30 July 1945, sponsored by Mrs. James Cary Jones, Jr., wife of Rear Admiral James Cary Jones, Jr., USN; and...
.
Crew
Backup crew
Mission parameters
- MassMassMass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
: 1,352 kg - PerigeePerigeePerigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...
: 159 km - Apogee: 265 km
- InclinationInclinationInclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
: 32.5° - PeriodOrbital periodThe orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
: 88.5 min
Preparation
After the successful completion of the Mercury 5 flight that carried Enos, a chimpanzee, in late November 1961, a press conference was held in early December. Reporters asked NASA's Robert Gilruth who would be the first U.S. astronaut in orbit, piloting Mercury 6. He then announced the team members for the next two Mercury missions. John H. Glenn was selected as prime pilot for the first mission (Mercury 6), with M. Scott Carpenter as his backup. Donald K. Slayton and Walter M. Schirra were pilot and backup, respectively, for the second mission, Mercury 7Mercury-Atlas 7
-Backup crew:-Crew notes:The original prime crew for Mercury Atlas-7 was to have been Deke Slayton, with Schirra as his back-up. However Slayton was removed from all flight crew availability after the discovery of cardiac arrhythmia during a training run in the g-loading centrifuge...
.
The Mercury 6 launch vehicle, Atlas #109-D, arrived at Cape Canaveral the evening of November 30, 1961. NASA had wanted to launch Mercury 6 in 1961 (hoping to orbit an astronaut in the same calendar year as the Soviets did), but by early December it was apparent that the mission hardware would not be ready for launch until early 1962.
Mercury spacecraft #13 began taking form on McDonnell's St. Louis, Missouri assembly line in May 1960. It was chosen for the MA-6 mission in October, 1960 and delivered to Cape Canaveral on August 27, 1961. Mercury spacecraft #13 and Atlas #109-D were stacked on the pad at Launch Complex 14 on January 2, 1962.
Launch delays
The launch date was first announced as January 16, 1962, then postponed to January 23 because of problems with the Atlas rocket fuel tanks. The launch then slipped day by day to January 27 due to inclement weather.On January 27, 1962, John Glenn was onboard Mercury 6 and ready to launch, when, at T-20 minutes, the flight director called off the launch because of heavy overcast. The cloud cover would have prevented the necessary photo coverage of the launch. The launch was postponed until February 1, 1962.
When technicians began to fuel the Atlas on January 30, they discovered a fuel leak had soaked an internal insulation blanket between the fuel and oxidizer tanks of the rocket. This caused a two week delay while necessary repairs were made. On February 15, the launch was again postponed due to weather. Finally on February 19, the weather started to break. It appeared that February 20, 1962 would be a favorable day to attempt a launch.
Launch
John Glenn boarded the Friendship 7 spacecraft at 11:03 UTC on February 20, 1962. The hatch was bolted in place at 12:10 UTC. Most of the 70 hatch bolts had been secured, when one was discovered to be broken. This caused a 42 minute delay while all the bolts were removed, the defective bolt was replaced and the hatch was re-bolted in place.At 14:47 UTC, after two hours and 17 minutes of holds and three hours and 44 minutes after Glenn entered Friendship 7, engineer T.J. O'Malley
T.J. O'Malley
Thomas Joseph O'Malley , better known as T. J. O'Malley, was an Irish-American aerospace engineer who, as chief test conductor for the Convair division of General Dynamics, was responsible for pushing the button on February 20, 1962 launching the Mercury-Atlas 6 space flight carrying astronaut John...
pressed the button in the blockhouse launching the spacecraft. At liftoff Glenn's pulse rate climbed to 110.
Thirty seconds after liftoff the General Electric-Burroughs guidance system locked onto a radio transponder in the booster to guide the vehicle to orbit. As the Atlas and Friendship 7 passed through Max Q
Max Q
In aerospace engineering, the maximum dynamic pressure, often referred to as maximum Q or max Q, is the point at which aerodynamic stress on a vehicle in atmospheric flight is maximized...
Glenn reported, "It's a little bumpy about here." After Max Q the flight smoothed out. At two minutes and 14 seconds after launch, the booster engines cut off and dropped away. Then at two minutes and twenty-four seconds, the escape tower
Escape tower
An Escape Tower, the original version officially known as the Aerial Capsule Emergency Separation Device, is the visible part of the Launch Escape System. It consists of a rocket and a frame attaching it to the top of the crew capsule...
was jettisoned, right on schedule.
After the tower was jettisoned, the Atlas and spacecraft pitched over still further, giving Glenn his first view of the horizon. He described the view as "a beautiful sight, looking eastward across the Atlantic." Vibration increased as the last of the fuel supply was used up. At sustainer engine cut-off it was found that the Atlas had accelerated the capsule to a speed only 7 ft/s (2 m/s) below nominal. At 14:52 UTC, Friendship 7 was in orbit. Glenn received word that the Atlas had boosted the MA-6 into a trajectory that would stay up for at least seven orbits. Meanwhile, computers at the Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...
in Maryland indicated that the MA-6 orbital parameters appeared good enough for almost 100 orbits.
First orbit
- 36 lb (16.3 kg) for automatic and
- 24.4 lb (11.1 kg) for manual control system
The spacecraft then settled into orbital flight with a velocity of 17,544 mph (7,843 m/s).
Friendship 7 began its first orbit with all systems go. It crossed the Atlantic and passed over the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
. Controllers there reported all capsule systems in perfect working order. Looking at the African coastline, and later the interior over Kano
Kano
Kano is a city in Nigeria and the capital of Kano State in Northern Nigeria. Its metropolitan population is the second largest in Nigeria after Lagos. The Kano Urban area covers 137 sq.km and comprises six Local Government Area - Kano Municipal, Fagge, Dala, Gwale, Tarauni and Nassarawa - with a...
, Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...
, Glenn told the tracking station team that he could see a dust storm. Kano flight communicators replied that the winds had been quite heavy for the past week.
Over Kano, Glenn took control of the spacecraft and started a major yaw adjustment. He allowed the spacecraft to continue the yaw maneuver until it was facing into its flight path. Glenn noticed that the attitude indicators disagreed with what he observed were the true spacecraft attitudes. Even with the incorrect instrument readouts, he was pleased to be facing forward instead of backward on his orbital path.
Over the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, Glenn observed his first sunset from orbit. He described the moment of twilight as "beautiful." The sky in space was very black, he said, with a thin band of blue along the horizon. He said sun set fast, but not as quickly as he had expected. For five or six minutes there was a slow reduction in light intensity. Brilliant orange and blue layers spread out 45 to 60 degrees on either side of the sun, tapering gradually toward the horizon. Clouds prevented him from seeing a mortar
Mortar (weapon)
A mortar is an indirect fire weapon that fires explosive projectiles known as bombs at low velocities, short ranges, and high-arcing ballistic trajectories. It is typically muzzle-loading and has a barrel length less than 15 times its caliber....
flare fired by the Indian Ocean tracking ship as part of a pilot observation experiment.
Continuing his journey on the night side of Earth, nearing the Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n coastline, Glenn made star, weather, and landmark observations. He looked for but failed to see the dim light phenomenon known as the zodiacal light
Zodiacal light
Zodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders...
; his eyes had insufficient time to adapt to the darkness.
The spacecraft came into radio range of Muchea
Muchea Tracking Station
Established in 1960, Muchea Tracking Station was built specifically for NASA's Project Mercury. It was Station No. 8 of 14 sites around the world used throughout the project. The only other Australian site was No...
, Australia. At the Mercury Tracking Station there, Gordon Cooper was the capsule communicator. Glenn reported that he felt fine and had no problems. He saw a very bright light and what appeared to be the outline of a city. Cooper said that he probably was looking at the lights of Perth
Perth, Western Australia
Perth 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....
and its satellite town of Rockingham
Rockingham, Western Australia
Rockingham is a suburb and primary centre in Western Australia south-west of the Perth city centre and south of Fremantle. It has a beachside location at Mangles Bay, the southern extremity of Cockburn Sound. To its north stretches the maritime and resource-industry installations of Kwinana and...
. This turned out to be correct; many people in Perth turned on their lights so as to be visible to Glenn as he passed over. "That sure was a short day," he excitedly told Cooper. "That was about the shortest day I've ever run into."
The spacecraft moved across Australia and across the Pacific to Canton Island. Glenn experienced a short 45 minute night and prepared the periscope for viewing his first sunrise from orbit. As the sun rose over the island, he saw thousands of "little specks, brilliant specks, floating around outside the capsule"; he momentarily felt that the spacecraft was tumbling or that he was looking into a star field. A quick hard look out of the spacecraft window corrected the illusion and Glenn was sure that the "fireflies", as he called them, were streaming past his spacecraft from ahead. They seemed to flow by slowly but did not seem to be coming from any part of the spacecraft, and they disappeared as Friendship 7 moved into brighter sunlight. It was later determined that they were probably small ice crystals venting from onboard spacecraft systems.
I am in a big mass of some very small particles, they're brilliantly lit up like they're luminescent. I never saw anything like it. They round a little: they're coming by the capsule and they look like little stars. A whole shower of them coming by. They swirl around the capsule and go in front of the window and they're all brilliantly lighted.John Glenn started banging the capsule wall and watched the "fireflies" come off,just as Alan Shepard did.
Guaymas
Guaymas is a city and municipality located in the southwest part of the state of Sonora in northwestern Mexico. The city is located 117 km south of the state capital of Hermosillo, and 242 miles from the U.S. border, and is the principal port for the state. The municipality is located in the...
, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, informed Mercury Control in Florida that a yaw thruster was causing attitude control problems. Glenn later recalled, this problem "was to stick with me for the rest of the flight."
Glenn noticed the control problem when the automatic stabilization and control system allowed the spacecraft to drift about a degree and a half per second to the right. Glenn switched control to manual-proportional control mode and moved Friendship 7 back to the proper attitude. He tried different control modes to see which used the least fuel to maintain attitude. The manual fly-by-wire combination used the least fuel. After about twenty minutes the yaw thruster began working again and Glenn switched back to the automatic control system. It worked for a short time and then began having problems again, this time with the opposite yaw thruster. He then switched back to the manual fly-by-wire system and flew the spacecraft in that mode for the remainder of the flight.
Second orbit
As Friendship 7 crossed Cape CanaveralCape Canaveral
Cape Canaveral, from the Spanish Cabo Cañaveral, is a headland in Brevard County, Florida, United States, near the center of the state's Atlantic coast. Known as Cape Kennedy from 1963 to 1973, it lies east of Merritt Island, separated from it by the Banana River.It is part of a region known as the...
at the start of its second orbit, a flight controller noticed that "Segment 51", a sensor providing data on the spacecraft landing system, was giving a strange reading. According to the reading, the heat shield and landing bag were no longer locked in position. If this were the case, the heat shield was only being held against the spacecraft by the straps of the retro package. Mercury Control ordered all tracking sites to monitor "Segment 51" closely and advise Glenn that the landing-bag deploy switch should be in the "off" position.
Glenn was not immediately aware of the problem, but he became suspicious when site after site asked him to make sure that the landing-bag deploy switch was off. Meanwhile Friendship 7 was crossing the Atlantic for the second time. Glenn was busy manually keeping the spacecraft attitude correct and also trying to accomplish as many of the flight plan tasks as he could.
Crossing over the Canary Islands, Glenn observed that the "fireflies" outside the spacecraft had no connection with gas from the reaction control jets. His suit temperature felt too warm, but he didn't take time to adjust it. The Kano, Nigeria and Zanzibar
Zanzibar
Zanzibar ,Persian: زنگبار, from suffix bār: "coast" and Zangi: "bruin" ; is a semi-autonomous part of Tanzania, in East Africa. It comprises the Zanzibar Archipelago in the Indian Ocean, off the coast of the mainland, and consists of numerous small islands and two large ones: Unguja , and Pemba...
sites suddenly noticed a 12 percent drop in the spacecraft secondary oxygen supply.
During his second pass over the Indian Ocean, Glenn found that the Indian Ocean tracking ship was in heavy weather. The tracking station had planned to release balloons for a pilot observation experiment, but instead the ship fired star-shell parachute flares as Friendship 7 passed overhead. Glenn was able to observe the flashes of lightning from storms in the area but was unable to see the flares.
The temperature in Glenn's spacesuit was too warm. It had been since he passed over the Canary Islands, earlier in the second orbit. As he crossed the Indian Ocean he tried to adjust the suit temperature. As he approached Woomera, Australia, a signal light came on warning him of excess cabin humidity. For the rest of the flight Glenn had to carefully balance suit cooling against the cabin humidity.
While he was still over Australia, another warning light came on, indicating that the fuel supply for the automatic control system was down to 62 percent. Mercury Control recommended that Glenn let the spacecraft attitude drift to conserve fuel.
There were no more problems for Friendship 7 during the remainder of the second orbit. Glenn continued to manually control the spacecraft attitude, not allowing it to drift too far out of alignment. In doing so, he consumed more fuel than a functioning automatic system would have used. Fuel consumption was 6 pounds (2.7 kg) from the automatic tank and 11.8 pounds (5.4 kg) from the manual tank, during the second orbit. This amounted to almost 30 percent of the total fuel supply.
Third orbit
On the third orbit of Friendship 7, the Indian Ocean tracking ship did not attempt to launch any objects for pilot observation experiments, as the cloud coverage was still too thick. When the spacecraft came across Australia for the third time, Glenn joked with Cooper at the Muchea Tracking StationMuchea Tracking Station
Established in 1960, Muchea Tracking Station was built specifically for NASA's Project Mercury. It was Station No. 8 of 14 sites around the world used throughout the project. The only other Australian site was No...
. Glenn asked Cooper to notify General Shoup, Commandant of the Marine Corps, that three orbits should meet the minimum monthly requirement of four hours' flying time. He also asked to be certified as eligible for his regular flight pay.
Reentry
Mercury Control was still undecided on the course of action to take. Some controllers thought the retrorocket
Retrorocket
A retrorocket is a rocket engine providing thrust opposing the motion of a spacecraft, thereby causing it to decelerate.-History:...
pack should be jettisoned after retrofire, while other controllers thought the retro pack should be retained, as added assurance that the heat shield would stay in place. Flight Director Chris Kraft and Mission Director Walter C. Williams, decided to keep the retro pack in place during reentry. Walter Schirra, the California communicator at Point Arguello, relayed the instructions to Glenn: the retro pack should be retained until the spacecraft was over the Texas tracking station. After the mission was over, the "Segment 51" warning light problem was later determined to be a faulty sensor switch, meaning that the heat shield and landing bag were in fact secure during reentry.
Glenn was now preparing for reentry. Retaining the retro package meant he would have to retract the periscope manually. He would also have to activate the 0.05-g sequence by pushing the override switch. Friendship 7 neared the California coast. It had been four hours and 33 minutes since launch. The spacecraft was maneuvered into retrofire attitude and the first retrorocket fired. "Boy, feels like I'm going halfway back to Hawaii," Glenn radioed. The second and then the third retros fired at five second intervals. The spacecraft attitude was steady during retrofire. Six minutes after retrofire; Glenn maneuvered the spacecraft into a 14 degree nose up, pitch attitude for reentry.
Friendship 7 lost altitude in its reentry glide over the continental United States, and headed toward splashdown in the Atlantic. The Texas tracking station told Glenn to retain the retro pack until the accelerometer read 1.5 g (14.7 m/s²). Glenn reported as he crossed Cape Canaveral he had been controlling the spacecraft manually and would use the fly-by–wire mode as a backup. Mercury Control then gave him the 0.05 g (0.49 m/s²) mark, and he pressed the override button. About the same time, Glenn heard noises that sounded like "small things brushing against the capsule." "That's a real fireball outside," he radioed Mercury Control. A strap from the retro package broke partially loose and hung over the spacecraft window as it was consumed in the reentry plasma stream. The spacecraft control system was working well but the manual fuel supply was down to 15 percent. The peak of reentry deceleration was still to come. Glenn switched to fly-by-wire and the automatic tank supply. This combination had more available fuel.
The spacecraft now experienced peak reentry heating. Glenn later reported, "I thought the retro pack had jettisoned and saw chunks coming off and flying by the window." He feared the chunks were pieces of his heatshield that might be disintegrating. The chunks were pieces of the retro package breaking up in the reentry fireball.
After passing the peak g region, the Friendship 7 began oscillating severely. The astronaut could not control the ship manually. The spacecraft was oscillating past 10 degrees on both sides of the vertical zero-degree point. "I felt like a falling leaf," Glenn later said. He activated the auxiliary damping system, this helped stabilize the large yaw and roll rates. Fuel in the automatic tanks was getting low. Glenn wondered if the spacecraft would retain stability until it was low enough to deploy the 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...
.
The automatic fuel supply ran out at 1 minute and 51 seconds, and manual fuel ran out at 51 seconds, before drogue chute deployment. The oscillations resumed, at 35,000 feet (10 km) Glenn decided to deploy the drogue chute manually to regain attitude stability. Just before he reached the switch, the drogue chute opened automatically at 28,000 feet (8.5 km) instead of the programmed 21,000 feet (6.4 km). The spacecraft regained stability and Glenn reported, "everything was in good shape."
At 17,000 feet (5 km) the periscope opened and was available for the astronaut to use. Glenn tried to look out the overhead window instead, but it was coated with so much smoke and film that he could see very little. The spacecraft continued to descend on the drogue chute. The antenna section jettisoned and the main chute deployed and opened to its full diameter. Mercury Control reminded Glenn to manually deploy the landing bag. He toggled the switch and the green light confirmation came on. A "clunk" could be heard as the heat shield and landing bag dropped into place, four feet (1.2 m) below the capsule.
Splashdown
According to a chart printed in the NASA publication Results of the First United States Manned Orbital Space Flight, Feb. 20, 1962, the spacecraft splashed down in the Atlantic at coordinates near 21°20′N 68°40′W, 40 miles (60 km) short of the planned landing zone. http://science.ksc.nasa.gov/history/mercury/ma-6/docs/ma-6-results.pdf Retrofire calculations had not taken into account spacecraft weight loss due to use of onboard consumables. The USS NoaUSS Noa (DD-841)
USS Noa was a of the United States Navy, the second Navy ship named for Midshipman Loveman Noa .Noa was laid down by the Bath Iron Works, Bath, Maine, on 26 March 1945; launched on 30 July 1945, sponsored by Mrs. James Cary Jones, Jr., wife of Rear Admiral James Cary Jones, Jr., USN; and...
, a destroyer code-named Steelhead, had spotted the spacecraft when it was descending on its parachute. The destroyer was about six miles (10 km) away when it radioed Glenn that it would reach him shortly. The Noa came alongside Friendship 7 seventeen minutes later.
One crewman cleared the spacecraft antenna and another crewman attached a line to hoist Friendship 7 aboard. After being pulled from the water the spacecraft bumped against the side of the destroyer. Once Friendship 7 was on deck, Glenn intended to leave the capsule through the upper hatch, but it was too hot in the spacecraft and Glenn decided to blow the side hatch instead. He told the ship's crew to stand clear and hit the hatch detonator plunger with the back of his hand. The detonator plunger recoiled, and slightly cut the astronaut's knuckles through his glove. With a loud bang, the hatch was off. A smiling John Glenn got out of Friendship 7 and stood on the deck of the Noa. His first words were, "It was hot in there."
Spacecraft location
Mercury spacecraft # 13 - Friendship 7 - is currently displayed at the National Air and Space MuseumNational Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
, Washington D.C. Mercury spacecraft #13 Friendship 7 display page on A Field Guide to American Spacecraft website.
On February 21, 1962, a metal fragment was recovered on a farm in South Africa. It was identified as coming from the MA-6 Atlas launch vehicle by numbers stamped on it. The fragment had landed on the farm after about eight hours in orbit.
Mercury-Atlas 6 flight events
| T+ Time | Event | Description |
|---|---|---|
| T+00:00:00 | Liftoff | Mercury-Atlas lifts off, onboard clock starts. |
| T+00:00:02 | Roll Program | Mercury-Atlas rotates along its axis 2.5 deg/s from 30 to 0 deg. |
| T+00:00:16 | Pitch Program | Mercury-Atlas begins a 0.5 deg/s pitch from 90 to 0 deg. |
| T+00:00:30 | Radio Guidance Lock | General Electric-Burroughs guidance system locks onto radio transponder in Atlas booster to guide the vehicle until orbit insertion. |
| T+00:01:24 | Max Q | Maximum dynamic pressure 980 lbf/ft² (6.75 MPa) |
| T+00:02:10 | BECO | Atlas Booster Engine Cutoff. Booster engines drop away. |
| T+00:02:33 | Tower Jettison | Escape Tower Jettison, no longer needed. |
| T+00:02:25 | Atlas Pitchover | After tower separation, vehicle pitches over further. |
| T+00:05:20 | SECO | Atlas Sustainer Engine Cutoff, capsule reaches orbit, velocity 17,547 mph (7,844 m/s) |
| T+00:05:24 | Capsule Separation | Posigrade rockets fire for 1 s giving 15 ft/s (4.57 m/s) separation. |
| T+00:05:25 | 5 second Rate Damping | ASCS damps capsule rates for 5 seconds in preparation for turnaround maneuver. |
| T+00:05:25 | Turnaround Maneuver | Capsule (ASCS) system rotates capsule 180 degrees, to heat shield forward attitude. Nose is pitched down 34 degrees to retro fire position. |
| T+00:05:30 T+04:30:00 |
Orbital Operations | Orbital operations and experiments for 3 orbits. |
| T+04:30:00 | Retro Sequence Start | Retrofire in 30 s. (ASCS) checks for proper retro attitude -34 deg pitch, 0 deg yaw, 0 deg roll. |
| T+04:30:30 | Retrofire | Three retro rockets fire for 10 seconds each. They are started at 5 second intervals, firing overlaps for a total of 20 s. Delta V of 550 ft/s (168 m/s) is taken off forward velocity. |
| T+04:35:45 | Retract Periscope | Periscope is retracted in preparation for reentry. |
| T+04:36:15 | Retro Pack Jettison | One minute after retrofire retro pack is jettisoned, leaving heatshield clear. (Was overridden in the mission.) |
| T+04:36:20 | Retro Attitude Maneuver | (ASCS) orients capsule in 34 degrees nose down pitch, 0 degrees roll, 0 degrees yaw. |
| T+04:42:15 | .05 G Maneuver | (ASCS) detects beginning of reentry and rolls capsule at 10 deg/s to stabilize capsule during reentry. |
| T+04:49:38 | Drogue Parachute Deploy | Drogue parachute deployed at 22,000 ft (6.7 km) slowing descent to 365 ft/s (111 m/s) and stabilizing capsule. |
| T+04:49:45 | Snorkel Deploy | Fresh air snorkel deploys at 20,000 ft (6 km) ECS switches to emergency oxygen rate to cool cabin. |
| T+04:50:15 | Main Parachute Deploy | Main parachute deploys at 10,000 ft (3 km). Descent rate slows to 30 ft/s (9 m/s) |
| T+04:50:20 | Landing Bag Deploy | Landing Bag Deploys, dropping heat shield down 4 ft (1.2 m). |
| T+04:50:20 | Fuel Dump | Remaining hydrogen peroxide fuel automatically dumped. |
| T+04:55:30 | Splashdown | Capsule lands in water about 500 mi (800 km) downrange from launch site. |
| T+04:55:30 | Rescue Aids Deploy | Rescue aid package deployed. The package includes green dye marker, recovery radio beacon and whip antenna. |
See also
- SplashdownSplashdown (spacecraft landing)Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by American manned spacecraft prior to the Space Shuttle program. It is also possible for the Russian Soyuz spacecraft and Chinese Shenzhou spacecraft to land in water, though this is only a contingency...
- Space capsuleSpace capsuleA space capsule is an often manned spacecraft which has a simple shape for the main section, without any wings or other features to create lift during atmospheric reentry....
- Space explorationSpace explorationSpace exploration is the use of space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
- U.S. Space Exploration History on U.S. StampsU.S. space exploration history on U.S. stampsWith the advent of unmanned and manned space flight a whole new era of American history had presented itself. Keeping with the tradition of honoring the country's history on the face of U.S. postage stamps, the U.S. Post Office began honoring the various events with its commemorative postage stamp...
Further reading
- Mercury-Atlas 6 Radio Transcripts on spacelog.org
- NASA Mercury MA6 press kit - Jan 21, 1962
- This New Ocean: A History of Project Mercury - NASA SP-4201
- NASA NSSDC Master Catalog
- Results of the first US manned orbital space flight - Feb 20, 1962 (Friendship 7) NASA report - (PDF format)
- This New Ocean: A History of Project Mercury - NASA report (PDF format)
- Chronology of Project Mercury - NASA report (PDF format)