Vintage Space Fun Fact: The Mercury ‘7’s

Each of the Mercury missions had a name followed by the number 7. Alan Shepard flew Freedom 7, Gus Grissom in Liberty Bell 7, John Glenn aboard Friendship 7 (pictured), Scott Carpenter in Aurora 7, Wally Schirra flew Sigma 7, and Gordon Cooper aboard Faith 7. Deke Slayton never flew because of a heart condition, but had he flown his mission would have been Delta 7.

So, what’s with all the ‘7’s? 

When NASA was preparing to send men into orbit, it had a series of suborbital and orbital test flight planned to make sure the hardware was man rated. For these tests, it needed capsule. Prime contractor McDonnell Douglas built 20 Mercury capsules, some were upgraded but they were all the same basic machine. (Right, Langley technicians build the Little Joe versions of the Mercury capsules in-house in Langley’s shops. At this point, the rocket was a testing workhorse.)

The first capsule was used on May 9, 1960 for a one minute and sixteen second beach abort test. The second launched on a Redstone rocket for an unmanned test of the control system on December 19, 1960. On March 18, 1961, the third capsule was lost during launch when an abort command failed to separate it from its Little Joe rocket. The fourth capsule was the first launched on an Atlas rocket on July 29, 1960. The capsule was lost during launch, and so never made it to its planned orbital altitude. The fifth capsule was launched January 31, 1961, on a ballistic flight. Luckily for its passenger, Ham the chimp, this one was successful. The sixth capsule was another unmanned ballistic launch on February 21, 1961, this time on an Atlas. (Left, all that remained of the fourth capsule after the Atlas exploded during launch. 1960.)

Then the seventh capsule carried Al Shepard in Freedom 7 on May 5, 1961. Shepard chose the name Freedom because it was patriotic. He added the ‘7’ not to commemorate the seven astronauts but because his was the seventh capsule off the production line. It was an internal designation. But it seemed like a good idea for the program to pay tribute to the seven brave men that were putting their hides on the line to ride rockets into space. It was great PR, and the public loved it. So when Gus Grissom followed in Al Shepard’s suborbital footprints, he chose Liberty Bell for his capsule’s name and also added the ‘7’. (Right, Shepard walks towards his Freedom 7 capsule on launch day. 1961.)

In the interest of a complete history, here’s a brief recap of what happened to the rest of the capsules.

The eighth went into orbit twice, once on April 23 and again on September 13, in 1961. Capsule nine launched on November 29, 1961 with the chimp Enos on board. The eleventh capsule carried Gus Grissom on his suborbital flight on July 21, 1961. The thirteenth carried John Glenn into orbit on February 20, 1962. The fourteenth was launched on a Little Joe rocket on April 28, 1961 as a test of the abort system and parachutes. The sixteenth carried Wally Schirra into orbit on October 3, 1962. The eighteenth carried Scott Carpenter around the globe on May 24, 1962. Finally, the twentieth capsule took Gordon Cooper into space on May 15, 1963. (Left, Grissom and Liberty Bell 7. 1961)

The tenth, twelfth, fifteenth, seventeenth, and nineteenth were never flown. Number ten was a test capsule, twelve backed up John Glenn’s mission, fifteen and seventeen were on hand to back up any manned orbital mission, and nineteen backed up Wally Schirra’s flight.

Suggested Reading

Where are the Mercury capsules now?

Project Mercury: A Chronology


6 thoughts on “Vintage Space Fun Fact: The Mercury ‘7’s

  1. The real sequence of Mercury spacecraft numbering was a bit more complicated than the article suggests. Each spacecraft got a number when it was built but the spacecraft numbers didn’t follow the same sequence as the flights, they were really production serial numbers and some got renumbered when they were either reused after a failed mission or their original mission changed. The sequence of flown Mercury spacecraft was:

    1) SC-1, 9 May 1960, Beach Abort Test
    2) SC-4, 29 Jul 1960, MA-1 – destroyed on launch
    3) SC-3, 8 Nov 1960, LJ-5, qualification of “Production” spacecraft
    4) SC-2, 21 Nov 1960,MR-1 first Redstone flight “the 6-inch” liftoff and shutdown
    5) SC-2A, 19 Dec 1960, MR-1A successful Redstone flight, SC-2A was just SC-2 renamed, it used the same Redstone booster.
    6) SC-5, 31 Jan 1961, MR-2, suborbital flight carrying Ham
    7) SC-6, 21 Feb 1961, MA-2, same test objectives as MA-1
    8) SC-14, 18 Mar 1961, LJ-5A, failed to meet objectives
    9) SC-8, 25 Apr 1961, MA-3, Mission was to put a production spacecraft into a single orbit, launch aborted, but the spacecraft was recovered.
    10) 28 Apr 1961, SC-14A (re-designation of SC-14), reflight of LJ-5A
    11) SC-7, 5 May 1961, MR-3 a.k.a Freedom 7, first manned suborbital Mercury flight by Alan Shepard.
    12) SC-11, 21 Jul 1961, MR-4 a.k.a. Liberty Bell 7, second manned suborbital flight by Gus Grissom. This was also the first manned spacecraft to have the trapezoidal window and other changes, and was close to identical to the spacecraft flown by Glenn and Carpenter.
    13) SC-8A, 12 Sep 1961, re-flight of the failed unmanned MA-3 mission using the same albeit re-designated spacecraft.
    14) SC-9, 29 Nov 1961, MA-5, completed 2 of 3 planned orbits, carrying the primate Enos.
    15) SC-13, 20 Feb 1962, MA-6 a.k.a. Friendship 7, first US Manned orbital flight with John Glenn
    16) SC-18, 24 May 1962, MA-7 a.k.a. Aurora 7, manned orbital flight with Scott Carpenter
    17) SC-16, 3 Oct 1962, MA-8 a.k.a. Sigma 7, manned orbital flight with Wally Schirra.
    18) SC-20, 15-16 May 1963, MA-9 a.k.a. Faith 7, last manned Mercury orbital flight with Gordon Cooper.

    Other flights both before and after the beach abort test, such as the early Little Joe missions, the Big Joe, mission and the MR-BD flight which was inserted to man-rate the Redstone when MR-2’s performance didn’t satisfy Von Braun, used non-production ‘boilerplate’ spacecraft.

    So Shepard’s Spacecraft had the production serial number of 7, but it was actually the 11th production spacecraft flown.

    And I would argue that there were two major, and different production blocks of the Mercury spacecraft, the first block had small porthole windows instead of the single larger trapezoidal window in front of the astronaut, and had a hatch which needed to be bolted and unbolted to open. Only Shepard flew a Spacecraft from this block.

    Grissom’s spacecraft and the four orbital spacecraft started out as almost identical, but as the program progressed changes were made, primarily removing items which were deemed not to needed, or not to pull their weight. Only Grissom and Glenn’s spacecraft carried the “Earth Path Indicator” on the instrument panel, a little clockwork driven globe to show the astronaut where he was positioned over the earth. This was superfluous for MR-4, and Glenn found it unnecessary.

    Sigma 7 had more equipment stripped out, to make room for some additional experiments and supplies for a six orbit flight, twice as long as the three orbit missions of Glenn and Carpenter.

    Faith seven stripped out more and added more supplies for its 22 orbit mission.

    And the un-flown SC were: SC-10, SC-12,
    SC-15, which was re-designated SC-15A and SC-15B as it was being prepared for a MA-10 mission for Shepard which was ultimately cancelled, and SC 17
    SC 19

  2. The capsule locations are a tad out of date, inasmuch as Grissom’s capsule was indeed eventually recovered from the depths of the ocean and now resides at the Kansas Cosmosphere – a journey worth an article in itself. The reuse of a Mercury capsule on an orbital flight is news to me, as I had always presumed that the first reused spacecraft was Gemini 2 on the MOL test flight – presumably this was the first reused spacecraft (not counting abort test articles). Or did the Soviets refly not-quite-manned Vostoks…

  3. Great website! I just finished reading “Carrying the Fire” by Michael Collins – one of the best books about the early space programs ever – fits right in with this blog – also liked the Gene Kranz book about Apollo 13. It’s kind of sad we’re reduced to watching China and Russia for any manned flight. I go out every clear night to watch satellites listed on the Heavens Above site – cool the see Phobos-Grunt, Tiangong, ISS, and tons of others go over – especially the ISS – knowing there are people looking back at me!

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