N4HY sent this note:
There was one series string of Nicads as can easily be discerned from this photograph:
http://n4hy.smugmug.com/gallery/2053069/1/105529609
You can notice the series string starts at the upper left and works its way right and then down to the lower string and back to the left.
Bob N4HY
Those are sealed, space-rated NiCd batteries built to NASA's specification. The package you see is the flight spare for the Radio Astronomy Explorer (RAE) satellites. They originally cost ~$2000 per cell. With later satellites, AMSAT found that we could "make our own" batteries that were better by carefully screening industrial-grade commercial batteries by following a recipe devised by the late Larry Kayser VE3QB/VA3LK/WA3ZIA.
RAE-A = Explorer 38 (http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1968-055A), launched July 4th, 1968 flew in MEO. This satellite had a a pair of Vee-beam antennas which provided gravity gradient stabilization. With each Vee-beam being 750' long, the satellite's 1500' total length made it the biggest structure put into space. The antenna booms were made of flat beryllium copper tape that formed itself into a round tube after being unrolled.
RAE-B = Explorer 49 flew June 15th, 1973 into Lunar orbit (http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1973-039A). It also had the same long Vee-beam antenna. The very lumpy lunar gravity field made for interesting problems with the gravity gradient booms!
FYI -- I note with some pride that I came to Goddard in 1968 as a staff scientist working on RAE-A and then RAE-B. I migrated from low-frequency radio astronomy into Pulsar and VLBI work. FYI#2 -- In addition to the flight spare batteries, Oscar-8's 10M antennas owed their existence to the RAE project.
73, de Tom K3IO (ex W3IWI)
Sil -- you have very sharp eyes. AO-7 was designed with a ~13.5v (i.e. 10@ NiCd cells) bus. The RAE battery was already assembled for the NASA mission with 12 cells. As a result, two cells were not used. The Orange & Black wires going to the DA-9 connector are indeed the battery's "gozinta/gozouta" wires. a V/2 telemetry tap (white) is at the right-hand end. The other wires are for thermistors.
The battery box was carefully sized to the cells. The cells expand when they get hot (under charging) and you will see thin Teflon sheets between the cells, and thicker Teflon sheets surrounding the pack, to provide som cushion. In addition, the Teflon provided electrical insulation between the battery cases (as I recall, the cases were supposed to be insulated, but one of the failure modes for this type of battery was for the case to develop a leakage resistance to the NiCd "guts").
73, Tom
Tom,
Thanks. It's a great story and it's rather odd to think that two cells in that battery were launched into orbit with the rest, but were nothing more than packing (expensive packing too).
Perhaps the special merit of the "NASA" cells, over those selected by the "Kayser" process, is that the NASA were designed to go open circuit after 25 years in space (hi hi). However, while the commonly held view is that the satellite started working again because the battery became "open circuit", the telemetry suggests that it is not, so the real cause may be far more subtle.
There are some very fine wires coming out of the thermally conductive goo that holds the thermistor to cell no 5. Were these joined to the yellow and grey wires that disappear under the battery?
I guess there's a special "satellite design" reason that double wires are used (instead of one thicker one) for the current carrying battery leads?
Leaving aside Geoff's (vk2tfg) point that the telemetry may be irrelevant because of the doggy value in channel 6D, it would seem that the five top cells (between half volt point and +12V - numbers 2,3,4,5,6 counting clockwise) are being charged with a current of 80mA and have reached a terminal voltage of 6.4 volts (8.8 - 2.4). This represents a voltage of 1.28 per cell (6.4/5) and is thoroughly reasonable. This idea is supported by the temperature of cell number 5 at 60.28 C.
The five cells between the half voltage point and ground are not so healthy. The figure of 2.4 volts suggest that 3 of them are short circuited.
Of course anything could be happening. The whole box could be a morass of goo with leakage currents going everywhere.
I will try and capture some more telemetry myself, as soon as the house painting is finished and I can remount my satellite antennas..
Geoff,
You made a comment: "Check channel 6D, anything other than about 0.5 means that the others are likely to be dodgy (invalid)".
Can you tell me any more about this. How is the value should in channel 6D derived?
Boy, a circuit diagram would be a diagnostic great tool here.
Sil - ZL2CIA
Sil - ZL2CIA wrote:
snipped
Geoff,
You made a comment: "Check channel 6D, anything other than about 0.5 means that the others are likely to be dodgy (invalid)".
Can you tell me any more about this. How is the value should in channel 6D derived?
Boy, a circuit diagram would be a diagnostic great tool here.
Sil - ZL2CIA
Hi Sil et al, this little snippet regarding channel 6D tells the story. It is from an e-mail Jan King sent after the bird was discovered .
voltage reference circuitry. The latter I know is working because the last telemetry value is 651. The "6" is just the row number of the telemetry value but the 51 means that the 1/2 volt reference is measuring 0.51 volts. I know that telemetry equation by heart since it was used as the calibration value for the rest of the telemetry system. So the telemetry has a fair chance of being decoded and making some sense
I really want to thank everyone, especially Dick Daniels, for being the photographic packrats we are. I also want to thank those who have sent me captions. I will steal Tom's note to make a caption for the batteries. A lot of new captions will go up this week. I am sure that this one example shows WHY this kind of photographic history is important and not just nostalgia. In my case, I have no memory. I knew I attended the earliest design meeting for AO-40. I did NOT remember it was the first five!
I have been off for almost two weeks for work and Thanksgiving and I will be playing catch up now.
Bob N4HY
Tom Clark, K3IO wrote:
N4HY sent this note:
There was one series string of Nicads as can easily be discerned from this photograph:
http://n4hy.smugmug.com/gallery/2053069/1/105529609
You can notice the series string starts at the upper left and works its way right and then down to the lower string and back to the left.
Bob N4HY
Those are sealed, space-rated NiCd batteries built to NASA's specification. The package you see is the flight spare for the Radio Astronomy Explorer (RAE) satellites. They originally cost ~$2000 per cell. With later satellites, AMSAT found that we could "make our own" batteries that were better by carefully screening industrial-grade commercial batteries by following a recipe devised by the late Larry Kayser VE3QB/VA3LK/WA3ZIA.
RAE-A = Explorer 38 (http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1968-055A), launched July 4th, 1968 flew in MEO. This satellite had a a pair of Vee-beam antennas which provided gravity gradient stabilization. With each Vee-beam being 750' long, the satellite's 1500' total length made it the biggest structure put into space. The antenna booms were made of flat beryllium copper tape that formed itself into a round tube after being unrolled.
RAE-B = Explorer 49 flew June 15th, 1973 into Lunar orbit (http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1973-039A). It also had the same long Vee-beam antenna. The very lumpy lunar gravity field made for interesting problems with the gravity gradient booms!
FYI -- I note with some pride that I came to Goddard in 1968 as a staff scientist working on RAE-A and then RAE-B. I migrated from low-frequency radio astronomy into Pulsar and VLBI work. FYI#2 -- In addition to the flight spare batteries, Oscar-8's 10M antennas owed their existence to the RAE project.
73, de Tom K3IO (ex W3IWI)
participants (4)
-
Geoff -
Robert McGwier -
Sil - ZL2CIA -
Tom Clark, K3IO