[amsat-bb] Friendship 7 details?

Daniel Schultz n8fgv at usa.net
Mon Jan 9 23:30:09 UTC 2017


Bob,

According to my coffee table book "The History of Manned Space Flight" by
David Baker (1982), the Mercury capsule was initially designed to support only
a three orbit mission, and both John Glenn and Scott Carpenter's flights were
planned to last only that long. Page 137 of this book describes extensive
modifications that were made to Wally Schirra's Sigma-7 spacecraft to allow it
to fly a six orbit mission. This leads to the interesting question of why
Glenn was told that he was "Go for at least seven orbits" by his capcom (page
118) when there was absolutely no possibility of his flight lasting that long.


The Navy had 24 ships including three aircraft carriers spread out across the
Atlantic to cover possible launch aborts and reentry after one, two or three
orbits (page 113). There was no mention of any recovery plans for more than
three orbits. 

The book also describes the flight of Enos the Chimp (page 105) in which
ground control was responsible for firing the retros (since the chimp had not
been trained on retrofire procedures). I don't know if that remote firing
capability was also carried on the manned flights. During Enos' flight the
telephone line between mission control at the Cape and the Point Arguello
tracking station was cut when a farmer in Arizona plowed up a telephone cable,
but Chis Kraft was able to reestablish voice contact to order Point Arguello
to transmit the retrofire command just seconds before the deadline. 

This very excellent book is marred only by the fact that it describes rocket
thrust in kilograms (one of my pet peeves), no doubt caused by English majors
in the publisher's editorial department who never took a physics course. 

Dan Schultz N8FGV


-------Original Message-------
Date: Mon, 9 Jan 2017 15:24:51 -0500
From: Robert Bruninga <bruninga at usna.edu>
Subject: [amsat-bb] Friendship 7 details?

After seeing the great movie ?hidden figures? last night, I had lots of
questions from my faded memory of the time (it was the same year I got my
ham license and was 14 years old).  This Wiki page has a lot? but the
questions lingering in my mind were:

https://en.wikipedia.org/wiki/Project_Mercury

1)      Was his mission planned at 3 orbits? (I thought it was more and
then cut to three).

2)      If #1, then they must have had to have recovery ships at a
different spot for every potential orbit since he could not maneuver
anything other than when to fire the retros.  If it was 7 cut to three,
then I guess they only needed two ship areas?

3)      What frequency was CAPCOM?  Was it the 108 MHz?   I think the
tracking stations all relayed the voice via HF?

4)      Also related to #1, if something happened to the pilot, I assume
ground control could fire the retros.



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