I just saw an interview with John Glenn, one of the space pioneers, on PBS. He was the first American to orbit Earth and reenter (and later a US Senator.) It awakened a memory probably worth sharing. Background: I was one of two technicians in the laboratory at Andrea Radio Corp. Collins Radio was the lead subcontractor for radio communications of the Mercury space capsules. They did the receivers and transmitters (four of each, IIRC) and sub-subcontracted the audio work to Andrea. The audio module consisted of six units; two headset amplifiers, two microphone amplifiers. a voice-operated transmit/receive switch, and an auxiliary telemetry channel. The headset and microphone amplifiers (specs on request) were matrixed so that if either one of a pair failed, the system would continue to work. The VOX could be bypassed with a manual switch. The telemetry channel was itself a backup. I laid out the circuit boards, built the prototypes, and made the wiring-harness board for the Mercury capsule audio module. It measured 3.5" square by 7" long, pretty good in the days before integrated circuits. I had left Andrea to return to college by the time of Glenn's historic ride. The whole country was focused on it. I was driving on a limited-access highway, listening to the reentry after the third orbit. Glenn mentioned seeing a red glow outside the capsule just all capsule before communications failed. All communications went through my box, and it was the obvious single point of failure. I won't even try to describe my feelings at the time. I turned off at the next (close) exit to avoid a distraction-induced accident. The solution occurred to me on the exit ramp, and I got to a pay phone almost at once. I told the operator that I had to talk to Mission Control immediately. Maybe it was something in my voice, but there were no questions and I was speaking to an engineer there in a good deal less than a minute. (Imagine that happening today.) I told him that the glow was probably a plasma from the ablation heat shield, and that given the antenna locations, the plasma had probably shorted them all out. He spoke to others in the room and then got back to tell me that I was probably right, and thanks. He asked me to wait on the line, then after a short time said that communication had been reestablished. We were both choked up with relief. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
OT Manned reentry
Started by ●February 20, 2012
Reply by ●February 20, 20122012-02-20
On Feb 20, 8:38�pm, Jerry Avins <j...@ieee.org> wrote:> I just saw an interview with John Glenn, one of the space pioneers, on > PBS. He was the first American to orbit Earth and reenter (and later a > US Senator.) It awakened a memory probably worth sharing. > > Background: I was one of two technicians in the laboratory at Andrea > Radio Corp. Collins Radio was the lead subcontractor for radio > communications of the Mercury space capsules. They did the receivers and > transmitters (four of each, IIRC) and sub-subcontracted the audio work > to Andrea. The audio module consisted of six units; two headset > amplifiers, two microphone amplifiers. a voice-operated transmit/receive > switch, and an auxiliary telemetry channel. The headset and microphone > amplifiers (specs on request) were matrixed so that if either one of a > pair failed, the system would continue to work. The VOX could be > bypassed with a manual switch. The telemetry channel was itself a backup. > > I laid out the circuit boards, built the prototypes, and made the > wiring-harness board for the Mercury capsule audio module. It measured > 3.5" square by 7" long, pretty good in the days before integrated > circuits. I had left Andrea to return to college by the time of Glenn's > historic ride. The whole country was focused on it. I was driving on a > limited-access highway, listening to the reentry after the third orbit. > Glenn mentioned seeing a red glow outside the capsule just all capsule > before communications failed. All communications went through my box, > and it was the obvious single point of failure. I won't even try to > describe my feelings at the time. I turned off at the next (close) exit > to avoid a distraction-induced accident. The solution occurred to me on > the exit ramp, and I got to a pay phone almost at once. I told the > operator that I had to talk to Mission Control immediately. Maybe it was > something in my voice, but there were no questions and I was speaking to > an engineer there in a good deal less than a minute. (Imagine that > happening today.) > > I told him that the glow was probably a plasma from the ablation heat > shield, and that given the antenna locations, the plasma had probably > shorted them all out. He spoke to others in the room and then got back > to tell me that I was probably right, and thanks. He asked me to wait on > the line, then after a short time said that communication had been > reestablished. We were both choked up with relief. > > Jerry > -- > Engineering is the art of making what you want from things you can get. > �����������������������������������������������������������������������You have a few friend on SED that may like this.
Reply by ●February 21, 20122012-02-21
On 2/20/2012 9:19 PM, brent wrote: ...> You have a few friend on SED that may like this.SED? Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●February 21, 20122012-02-21
On Mon, 20 Feb 2012 23:14:04 -0500, Jerry Avins wrote:> On 2/20/2012 9:19 PM, brent wrote: > > ... > >> You have a few friend on SED that may like this. > > SED? > > Jerrysci.electronics.design. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
Reply by ●February 21, 20122012-02-21
brent schrieb:>>I told him that the glow was probably a plasma from the ablation heat >>shield, and that given the antenna locations, the plasma had probably >>shorted them all out. He spoke to others in the room and then got back >>to tell me that I was probably right, and thanks. He asked me to wait on >>the line, then after a short time said that communication had been >>reestablished. We were both choked up with relief.Hello, there were two missions with the Mercury capsule in an earth orbit before the manned mission with John Glenn, the communication problem during reentry should have been noticed before. Telemetry was used with these unmanned missions also. Bye
Reply by ●February 21, 20122012-02-21
On Feb 21, 6:22�am, Uwe Hercksen <herck...@mew.uni-erlangen.de> wrote:> brent schrieb: > > >>I told him that the glow was probably a plasma from the ablation heat > >>shield, and that given the antenna locations, the plasma had probably > >>shorted them all out. He spoke to others in the room and then got back > >>to tell me that I was probably right, and thanks. He asked me to wait on > >>the line, then after a short time said that communication had been > >>reestablished. We were both choked up with relief. > > Hello, > > there were two missions with the Mercury capsule in an earth orbit > before the manned mission with John Glenn, the communication problem > during reentry should have been noticed before. Telemetry was used with > these unmanned missions also. > > Byenicht brent schrieb: aber brent weitergeleitet: (Das mit der Hilfe von Google :-) getan (This done with the help of google :-)
Reply by ●February 21, 20122012-02-21
On 2/21/12 12:07 AM, Tim Wescott wrote:> On Mon, 20 Feb 2012 23:14:04 -0500, Jerry Avins wrote: > >> On 2/20/2012 9:19 PM, brent wrote: >> >> ... >> >>> You have a few friend on SED that may like this. >> >> SED? >> >> Jerry > > sci.electronics.design >yeah, brent, we say it like: " s.e.d " but comp.dsp is so short, we never abbreviate it. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
Reply by ●February 21, 20122012-02-21
Uwe Hercksen wrote:> > Hello, > > there were two missions with the Mercury capsule in an earth orbit > before the manned mission with John Glenn, the communication problem > during reentry should have been noticed before. Telemetry was used with > these unmanned missions also.Sure, but that was before NASA started buying all of their Telemetry receiving equipment from Microdyne. They bought it from the company that Microdyne put out of business. :) -- You can't have a sense of humor, if you have no sense.
Reply by ●February 21, 20122012-02-21
On 2/21/2012 6:22 AM, Uwe Hercksen wrote:> > > brent schrieb: > >>> I told him that the glow was probably a plasma from the ablation heat >>> shield, and that given the antenna locations, the plasma had probably >>> shorted them all out. He spoke to others in the room and then got back >>> to tell me that I was probably right, and thanks. He asked me to wait on >>> the line, then after a short time said that communication had been >>> reestablished. We were both choked up with relief. > > Hello, > > there were two missions with the Mercury capsule in an earth orbit > before the manned mission with John Glenn, the communication problem > during reentry should have been noticed before. Telemetry was used with > these unmanned missions also.There was no plasma problem with any of the the sub-orbital reentries. I can make a reasonable guess about why, but I don't know. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●February 21, 20122012-02-21
On Tue, 21 Feb 2012 12:23:37 -0500, Jerry Avins <jya@ieee.org> wrote:>On 2/21/2012 6:22 AM, Uwe Hercksen wrote: >> >> >> brent schrieb: >> >>>> I told him that the glow was probably a plasma from the ablation heat >>>> shield, and that given the antenna locations, the plasma had probably >>>> shorted them all out. He spoke to others in the room and then got back >>>> to tell me that I was probably right, and thanks. He asked me to wait on >>>> the line, then after a short time said that communication had been >>>> reestablished. We were both choked up with relief. >> >> Hello, >> >> there were two missions with the Mercury capsule in an earth orbit >> before the manned mission with John Glenn, the communication problem >> during reentry should have been noticed before. Telemetry was used with >> these unmanned missions also. > >There was no plasma problem with any of the the sub-orbital reentries. I >can make a reasonable guess about why, but I don't know.Not enough energy.
