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@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.