Mercury Redstone 4

Mission emblem

Mission dates

Mission:

Mercury Redstone 4 (MR-4)

COSPAR-ID :

MERCR4

Spacecraft:

Liberty Bell 7
serial number 11

Launcher:

Redstone Mercury , serial number MR-8

Crew:

1

Begin:

July 21, 1961, 12:20:36 UTC

Starting place:

LC-5 , Cape Canaveral

Landing:

July 21, 1961, 12:36:13 UTC

Landing place:

Atlantic
27 ° 32 ′ N , 75 ° 44 ′ W

Flight duration:

15min 37s

Earth orbits:

suborbital flight

Recovery ship:

USS Randolph

Apogee :

190.39 km

Covered track:

486.15 km

Maximum speed:

8317 km / h

Maximum acceleration:

11.1 g

Team photo

Virgil Grissom

◄ Before / After ►

Mercury Redstone 3 (manned)	Mercury Atlas 4 (unmanned)
Next manned mission:
	Mercury Atlas 6

The Mercury-Redstone 4 (MR-4) mission on July 21, 1961 was the second US space flight under the Mercury program . Reaching Earth orbit was not yet planned, but a suborbital flight was carried out. The landing capsule sank after the splash, and the astronaut Virgil Grissom could only swim to save himself.

crew

In January 1961, NASA selected Virgil "Gus" Grissom as the astronaut for the second suborbital Mercury mission. John Glenn was assigned as a replacement pilot . It was not announced to the public until July 15, a few days before the start.

All other Mercury astronauts were still involved in the flight control. Alan Shepard took on the role of Liaison Officer ( CapCom ) .

preparation

The Mercury spacecraft (serial number 11) was delivered to Cape Canaveral on March 7, 1961, the Redstone rocket (serial number 8) on June 12th.

The spaceship was named "Liberty Bell 7" by Grissom, after the shape that was reminiscent of the Liberty Bell in Philadelphia . While Shepard chose the number 7 for the previous flight because his spaceship was the seventh in this series, Grissom decided not to use the 11, but to keep the 7 as a symbol for the seven astronauts of the Mercury program. NASA employees even painted the characteristic crack of the Liberty Bell on the spaceship.

The Liberty Bell 7 has made two major design changes to the Freedom 7. A new, trapezoidal window allowed the astronaut to see outside. In addition, the exit hatch was provided with an explosive device that was supposed to blast the hatch outwards after landing in order to facilitate the exit. This new mechanism was to play a major role during the landing.

On May 25, President John F. Kennedy delivered his historic address to Congress announcing a manned landing on the moon before the end of the decade.

Flight history

Mercury 4 launch

The start was initially scheduled for July 18th, but was postponed to July 19th due to bad weather. Ten minutes before the end of the countdown, this start was also canceled and postponed by two days.

Finally, the Redstone rocket lifted off with the Liberty Bell 7 on top on July 21st. After two minutes and 22 seconds the engine shut down and the spaceship detached itself from the Redstone rocket. The speed at this point was 2 km / s. For about five minutes, Grissom was in weightlessness .

Grissom was able to turn the spaceship around several axes. The re-entry into the earth's atmosphere occurred with over 11g. After a ballistic flight and reaching the summit height of 190 km, an astronaut ignited the spacecraft's brake rocket by hand for the first time. During the descent, Grissom observed cracks in the parachute , but they did not enlarge. Finally, after a flight of 15 minutes and 37 seconds, the Liberty Bell 7 landed 487 km from the take-off point.

Almost disaster after the splashdown

The flight went without major problems until the landing . Helicopters had already flown to the landing site to take the astronaut on board as soon as he left the landing capsule. Grissom was still in the capsule when the hatch's explosive device went off and water seeped inside the capsule.

Grissom had already taken off his helmet and the oxygen lines and was able to escape into the sea through the open hatch. Had he still been buckled up, he would inevitably have drowned.

The two pilots of the helicopter closest to Liberty Bell 7 still managed to hook the landing capsule. They were about to turn to Grissom to get him on board when a warning lamp in the cockpit indicated that the engines were overloaded. Then a second helicopter was ordered to Grissom.

At first Grissom had no trouble staying afloat, because the air in the spacesuit gave him enough buoyancy. This air gradually escaped through the neck bulge, and water also flowed through the connections of the oxygen lines, so that it was more and more difficult for him to swim. He also had additional weight with him, as he had taken a number of souvenirs with him on his flight in the left leg of his spacesuit, including two rolls of 50-cent pieces for friends' children, three dollar bills, a few miniature models of the spaceship and two pilot badges. In addition, Grissom was hindered by the waves caused by the rotor wind of the second helicopter. He tried to get help from the helicopters by waving his arms, but the crews only interpreted it as a greeting from Grissom and waved him back in a friendly manner.

He was able to grab a lifebelt that was thrown to him, with the Grissom recovery bracket being put on the wrong way in panic and physical exhaustion. Then Grissom could be brought on board, although he was submerged twice. In total, Grissom had spent about four minutes in the water. On the way in the helicopter to the rescue aircraft carrier, he immediately put on a life jacket, as he was afraid that he might end up in the water again if the helicopter had problems. On board the aircraft carrier, an officer then handed him his helmet, which must have floated out of the sinking capsule and had been recovered by the crew of a destroyer.

In the meantime, the pilots of the first helicopter had given up all attempts to save the capsule. When full it weighed more than the machine could lift and there was a risk of overloading the engines. Finally, Liberty Bell 7 sank in the Atlantic to a depth of 5000 meters.

Recovery and restoration of the Liberty Bell 7

After several failed attempts in 1992 and 1993 succeeded on 20 July 1999, on the thirtieth anniversary of the moon landing of Apollo 11 of Oceaneering International , Inc. the recovery from the Atlantic. The recovery was funded by the Discovery Channel . The rescue team was Curt Newport , who had been looking for it for 14 years at a depth of 4,900 m, 300 nm (560 km) southeast of the Cape Canaveral Air Force Station . Among other things, parts of the spacesuit and 10-cent coins that had flown as souvenirs were recovered.

After the lashing of the Liberty Bell 7 on the deck of the salvage ship "Ocean Project", another explosive body (was SOFAR bomb ) removed. This should have triggered when the spaceship sank. The capsule was then sunk into a seawater tank to prevent further corrosion from atmospheric oxygen.

The capsule was disassembled and cleaned in Cosmosphere (Hutchinson, Kansas) and presented on a nationwide exhibition tour until September 15, 2006. In 2016 it was loaned to The Children's Museum of Indianapolis on short notice .

Follow-up examinations

The recovered Liberty Bell 7, 1999

The Liberty Bell 7 in the Bundeskunsthalle, 2014

To this day, it is not clear why the hatch cover was blown off. There were two trigger mechanisms: inside the landing capsule, the pilot could trigger the explosive device, and rescue teams could pull a T-handle from outside in an emergency.

Grissom vehemently contradicted the allegations that he could have blown off the hatch intentionally or unintentionally. On later Mercury flights, the astronauts also suffered minor hand injuries when they operated the explosive device. Grissom had no such injury, an indication that his hand was not on the trigger mechanism when the charge detonated. The allegations could not be completely dispelled until his death, six years later in the fire in the Apollo 1 spacecraft .

A commission with the participation of the astronaut Walter Schirra investigated the process and carried out further tests, but no premature explosion could be caused. An attempt to retrieve the capsule failed in 1994, but was successfully carried out in 1999. The capsule is on display at the Kansas Cosmosphere and Space Center . From October 3, 2014 to February 22, 2015 it was loaned to the Bundeskunsthalle in Bonn, where the original could be viewed in the exhibition “Outer Space”.

The current theory for the course of the accident is the following, but like all other unproven variant:

During the descent, Grissom observed a hole in one of the parachutes on the parachute, which was about the size of the outer cover of the trigger for the explosive bolt of the door. It is believed that a line of the parachute or the light buoy got caught in the lever and triggered it after landing. There were also several countdown stops before the start, one due to an incorrectly attached explosive bolt on the hatch.

After the mission, Grissom suggested that divers should be on board the rescue helicopter to secure the capsule with floats. This proposal was accepted by NASA in the Gemini project and applied without exception until the end of the Apollo missions, since all spacecraft had landed in the sea by then.

Significance to the Mercury program

Even if Liberty Bell was lost in the end, the Mercury spaceship had proven its ability to fly. Further suborbital test flights were canceled, the next Mercury flight was supposed to lead into earth orbit with an Atlas rocket , but with a monkey as a crew.

Grissom never got over the loss of the landing capsule. Even if the suspicion against him could never be dispelled without a doubt, he remained a respected member of the astronaut group and was later given command of the Americans' first two-man flight ( Gemini 3 ). He named this spaceship, in reference to the sunken Liberty Bell 7 Molly Brown , after the Broadway musical The Unsinkable Molly Brown . After the splash, he kept the hatch closed as long as possible.

Tragically, another hatch cost Grissom his life. During a test in an Apollo spaceship, a fire broke out and the rescue teams were unable to open the door in time, as no explosive device was attached to the hatches of the Apollo spaceships due to the near-catastrophe with the Liberty Bell. Grissom died with Ed White and Roger Chaffee in the Apollo 1 spacecraft .

Web links

Commons : Mercury-Redstone 4 - Collection of pictures, videos and audio files

NASA: Mission Overview (English)
NASA History Series: Liberty Bell Tolls in "This New Ocean: A History of Project Mercury"
NASA: Results of the second US manned suborbital space flight final report

Individual evidence

↑ ^a ^b Joseph A. Angelo: Human Spaceflight . Infobase Publishing, May 14, 2014, ISBN 978-1-4381-0891-9 , pp. 87-.
^ Air & Space Smithsonian . Smithsonian Institution, 2000.
^ Materials Performance . National Association of Corrosion Engineers, July 1999.
^ Robert Greenberger: Gus Grissom: The Tragedy of Apollo 1 . The Rosen Publishing Group, October 1, 2003, ISBN 978-0-8239-4458-3 , pp. 54-.
↑ it is permanently on display in the Cosmosphere. The Liberty Bell 7 Recovery . UXB. 2011. Archived from the original on March 18, 2013. Retrieved March 18, 2013.

[Angelo2014-1] Joseph A. Angelo: Human Spaceflight . Infobase Publishing, May 14, 2014, ISBN 978-1-4381-0891-9 , pp. 87-.

[2] Air & Space Smithsonian . Smithsonian Institution, 2000.

[3] Materials Performance . National Association of Corrosion Engineers, July 1999.

[Greenberger2003-4] Robert Greenberger: Gus Grissom: The Tragedy of Apollo 1 . The Rosen Publishing Group, October 1, 2003, ISBN 978-0-8239-4458-3 , pp. 54-.

[UXB-5] t is permanently on display in the Cosmosphere. The Liberty Bell 7 Recovery . UXB. 2011. Archived from the original on March 18, 2013. Retrieved March 18, 2013.