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Wed Feb 20, 2019, 07:31 AM

57 Years Ago Today; John Glenn is first American to Orbit the Earth

https://en.wikipedia.org/wiki/Mercury-Atlas_6



Mercury-Atlas 6

Mercury-Atlas 6 (MA-6) was the third human spaceflight for the U.S. and part of Project Mercury. Conducted by NASA on February 20, 1962, the mission was piloted by astronaut John Glenn, who performed three orbits of the Earth, making him the first U.S. astronaut to orbit the Earth.

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 North Atlantic Ocean and was safely taken aboard USS Noa.

The event was named an IEEE Milestone in 2011.



Launch

Glenn entering Friendship 7
Glenn boarded the Friendship 7 spacecraft at 11:03 UTC on February 20, 1962 following an hour-and-a-half delay to replace a faulty component in the Atlas's guidance system. 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. The count was resumed at 11:25 UTC. The gantry was rolled back at 13:20 UTC. At 13:58 UTC the count was held for 25 minutes while a liquid oxygen propellant valve was repaired.


Launch of Friendship 7
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.[ O'Malley said, "the good Lord ride all the way," and then capsule communicator Scott Carpenter uttered the famous phrase "Godspeed, John Glenn." Due to a glitch in Glenn's radio, he did not hear the Carpenter phrase during launch. At liftoff Glenn's pulse rate climbed to 110 beats per minute.

30 seconds after liftoff the General Electric-Burroughs designed 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. Booster performance had been nearly flawless through the entire powered flight. 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.

<snip>

Reentry
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. "Roger. Retros are firing. ... Are they ever. It feels like I'm going back toward 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". "This is Friendship 7 - 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 heat shield that might be disintegrating. The chunks were pieces of the retro package breaking up in the reentry fireball.

After passing the peak g region, 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.

Splashdown

The destroyer Noa hoists the Friendship 7 capsule aboard

The spacecraft splashed down in the North Atlantic at coordinates near 21°20′N 68°40′W, 40 miles (64 km) short of the planned landing zone. Retrofire calculations had not taken into account spacecraft weight loss due to use of onboard consumables. USS Noa, a destroyer code-named "Steelhead", had spotted the spacecraft when it was descending on its parachute. The destroyer was about 6 miles (9.7 km) away when it radioed Glenn that it would reach him shortly. 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 Glenn got out of Friendship 7 and stood on the deck of Noa. His first words were, "It was hot in there."

The astronaut and spacecraft came through the mission in good shape.

</snip>


Godspeed, John Glenn!

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Reply 57 Years Ago Today; John Glenn is first American to Orbit the Earth (Original post)
Dennis Donovan Feb 20 OP
Sherman A1 Feb 20 #1
DeeDeeNY Feb 20 #2
FarPoint Feb 20 #3
Dave Starsky Feb 20 #4
Dennis Donovan Feb 20 #5
Dave Starsky Feb 20 #6

Response to Dennis Donovan (Original post)

Wed Feb 20, 2019, 07:33 AM

1. I remember

These Mecrury capsules were built close to my home.

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Response to Dennis Donovan (Original post)

Wed Feb 20, 2019, 07:59 AM

2. What an amazing and dramatic story

I was in sixth grade but didn’t fully absorb it all at the time. Thanks for this beautiful reminder.

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Response to Dennis Donovan (Original post)

Wed Feb 20, 2019, 08:26 AM

3. A Hero if mine...

Had the pleasure of meeting him in Ohio.... Democrats State Dinner in Columbus.

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Response to Dennis Donovan (Original post)

Wed Feb 20, 2019, 09:08 AM

4. A dramatic reenactment...

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Response to Dave Starsky (Reply #4)

Wed Feb 20, 2019, 11:05 AM

5. Great scene from an exceptional movie!

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Response to Dennis Donovan (Reply #5)

Wed Feb 20, 2019, 02:45 PM

6. I think that was the first time I ever heard Holst's "The Planets".

And it was used perfectly.

That's one of my favorite movies of all time.

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