IIIRC, it was planned for 6 orbits. But when telemetry showed the landing bag deployed, it was cut to 3. Flight Director Kris Kraft was convinced,, based on report from controllers and the spacecraft that it was a faulty indication and wanted to go the full six. He was overruled by upper management. During t-shirt they told Glenn to keep the retro package on during re-entry, the idea being the straps would keep the heat shield attached and thus the landing bag stowed.
After the flight, Kraft lobbied for and got the rule added to tall mission profiles the "The Flight Director shall have the final authority for call decisions pertaining to completion of mission objectives and crew safety", essentially preventing management from interfering again.
Also IIRC there were two landing zones. In the event of an abort or, in this case, a shortening of the mission, retro fire would be planned for one of those. Now much after 6orbits, the rotation of earth, put the ground track out of range of groundbreaking station s for extended times. They had tracking stations on the Canadiens, Zanzibar Canberra, Hawaii & Goldstein, can (there may more,but those come to mind right now), so even under optimal conditions they were in direct contact with the spacecraft for about 10 minutes at a time maybe 4 or 5 times per orbit.
During Gemini VIII, when the spacecraft almost spun out of control due to a stuck thruster, they had to abort since Armstrong had used their reentry thrusters to recover. All that happened out of communication range. When they came back in range the abort was called at the first opportunity. This put them well away from the recovery area. The crew had to wait several hours before recovery teams got to them not being a boat, the capsule bombed around a lot. armstrong, being a Navy man rode it out, but Scott, who was Air force, spent the time puking his guts out.
Rick Tejera K7TEJ Saguaro Astronomy Club www.SaguaroAstro.org Thunderbird Amateur Radio Club www.w7tbc.org
On January 9, 2017, at 14:02, B J va6bmj@gmail.com wrote:
On 1/9/17, Robert Bruninga bruninga@usna.edu wrote:
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
Was his mission planned at 3 orbits? (I thought it was more andthen cut to three).
The comment by the capcom was that he was "good for 7 orbits", but the plan was for only 3.
If #1, then they must have had to have recovery ships at adifferent 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…
There were several potential landing sites during a mission in case something went wrong.
Gemini VIII, with Neil Armstrong and Dave Scott, had to be cut short after a few orbits because of the problem with one of the spacecraft's manoeuvring thrusters. It splashed down in one of the auxiliary recovery zones in the South China Sea and they were picked up by a USN destroyer.
That didn't always work as NASA found out during the next Mercury mission, Aurora 7. Carpenter apparently fired his retro thrusters a bit late and landed some 400 km away from he was supposed to.
What frequency was CAPCOM? Was it the 108 MHz? I think thetracking stations all relayed the voice via HF?
I don't believe so. I think the ground stations might have connected by telephone lines to Mission Control. The only signal fading would be when the spacecraft was out of range of a tracking station.
Also related to #1, if something happened to the pilot, I assumeground control could fire the retros.
If I remember correctly, the spacecraft was entirely under control of the pilot. During Shepard's mission, Freedom 7, the retros didn't fire automatically so he had to light them manually.
<snip>
73s
Bernhard VA6BMJ @ DO33FL _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb