Warning: Creating default object from empty value in /homepages/11/d132647312/htdocs/Amfone/mkportal/include/SMF/smf_out.php on line 47
NACA's ECHO 1 TV Satellite




 
The AM Forum
October 20, 2018, 04:20:26 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: NACA's ECHO 1 TV Satellite  (Read 13546 times)
0 Members and 1 Guest are viewing this topic.
W2DU
Contributing
Member
*
Offline Offline

Posts: 490

Walt, at 90, Now 92 and licensed 78 years


WWW
« on: January 05, 2011, 06:44:19 PM »

A few posts back my involvement with the ECHO Spacecraft was mentioned, so I thought a story about my involvement might be of interest to the AM group here. Thus I'm quoting from Reflections 3, Sec 28.3:

Sec 28.3  Echo 1 Spacecraft

     Launched into space on August 8, 1960, Echo 1 was the World’s first attempt to use an Earth-orbiting spacecraft as a means for achieving global TV broadcasting. When inflated after reaching orbit, Echo became a 100-ft spherical balloon made of aluminized mylar film of ˝ mil thickness. The aluminized coating on the mylar was used to reflect TV RF signals globally from high-powered transmitters for direct reception to TV receivers on the ground. Although the spacecraft performed correctly while in orbit, its intended use was unsuccessful, because the power required of the TV transmitters was too great to obtain a satisfactory picture on reception after the signal was reflected from the spacecraft.
     However, it is interesting to note that the spacecraft carried two beacon transmitters to verify a successful entry into space after launching from Cape Canaveral. There was concern that it could become lost in clouds, with no way to determine its location thereafter. Hence, the two beacons operating at 108.0 and 108.03 MHz to permit continual radio tracking of the balloon if lost from visual contact.
     The beacon units, mounted at opposite poles of the balloon, included the transmitter, batteries, antenna, and solar cells, were embedded in a plastic disc shaped like a dinner plate, as shown in Photo 28-3.1. The transmitter, shown with and without encasement in Photo 28-3.2, delivered a continuous wave one-hundredth of a watt (ten milliwatts) into the antenna, which produced S9+ signals at the ground stations when the spacecraft was just above the horizon at 1,800 miles distance. Photo 28-3.3 is a view of the bottom side of the unit, showing the transmitter, batteries, and printed circuit connecting the batteries to the solar cells. Photo 28-3.4 shows technicians attaching the beacon to the mylar balloon material with adhesive tape.
    The antenna for Echo 1 was designed by the Author, which by itself brings up an interesting story. The spacecraft was a child of NACA, the forerunner of NASA. RCA’s involvement was to design and build the beacons. However, the engineers at NACA specified emphatically that no wire antenna could be involved due to the possibility of its inadvertently protruding into the skin of the balloon, allowing it to deflate. They strongly suggested that we design the beacon to use a slot antenna by simply making the slot opening in the surface of the balloon. We rejected the slot approach, indicating that while half of the RF energy delivered to the antenna would be radiated outward, the other half would be radiated inward, thus entering the space within the balloon. Inward radiation of RF energy would be disastrous, because the space inside the balloon would form a resonant cavity with extremely high Q. The result would be a highly unstable input impedance for the slot antenna.
     Consequently, we at RCA suggested placing a cavity resonant at the beacon frequency directly behind the slot to prevent inward radiation, and thus all the energy would be radiated outward. However, the NACA engineers were not only skeptical that the high Q of the cavity would cause an unstable impedance for the antenna, but also said building such a cavity behind the slot was impractical. So it became incumbent on RCA to prove the instability of the antenna impedance in the absence of the resonant cavity behind the slot.
     Because it was obviously impractical to take measurements on a balloon 100 feet in diameter, the proof must be found using a scale model for the measurements. As the RF engineer assigned to the antenna development I chose a 100-to-1 scale factor for a measurement model, making the diameter of the model sphere one foot and the measurement frequency 10,800 MHz, or 10.8 GHz. The RCA Laboratories model shop pressed a piece of 1/32″ copper sheeting into a sphere of one foot diameter. (Don't ask me how they did it.)
     A slot with the appropriate dimensions for the 10.8 GHz frequency was cut into the sphere, and fed with RG-55 coaxial cable. As I predicted at the outset, the input impedance of the slot radiator proved to be immeasurable, because the values of SWR exceeded 100:1, varying wildly with small temperature changes in the model. The NACA engineers demanded a demonstration of the measurements performed at their location at Langley Air Force Base, Virginia, which the Author duly performed. The performance convinced the people at Langley that we were correct concerning the instability of the slot impedance without a resonant cavity backing the slot. They finally agreed to allow a stainless steel spring wire antenna after we (RCA) promised to secure the wire embedded in the beacon plate until after the balloon had inflated, to ensure that the wire would not damage the mylar skin of the balloon. Referring to Photo 28-3.1, observe the circular slot near the periphery of the beacon disc, with the wire antenna emerging on the right-hand side. The antenna wire was secured in this slot while the balloon was folded up prior to launch, but when the balloon was inflated the wire was released from the slot, becoming vertical in relation to the surface of the balloon. In addition, a switch at the point where the wire emerged was automatically turned to the ON position when the wire was released, connecting the batteries to the transmitter and thus turning the beacon on.
     Had the NACA engineers believed us concerning the high-Q nature of the space within the balloon, the engineering of the simple quarter-wave vertical antenna mounted over the spherical ground plane supplied by the aluminized coating on the mylar balloon material would have been routine, requiring only designing the mechanical means for preventing the antenna from tearing a hole in the balloon. It seems that it’s sometimes better to keep it simple for government work.



* Photo 28-3.4.jpg (599.04 KB, 2849x2132 - viewed 841 times.)

* Photo 28-3.1.jpg (598.89 KB, 2048x1536 - viewed 879 times.)

* Photo 28-3.2.jpg (193.13 KB, 1061x1570 - viewed 824 times.)
Logged

W2DU, ex W8KHK, W4GWZ, W8VJR, W2FCY, PJ7DU. Son Rick now W8KHK.
W2DU
Contributing
Member
*
Offline Offline

Posts: 490

Walt, at 90, Now 92 and licensed 78 years


WWW
« Reply #1 on: January 05, 2011, 06:59:50 PM »

For some reason, Fig 28-3.3 was not permitted on the earlier post with the other three figs.

Walt


* Photo 28-3.3.jpg (541.69 KB, 2773x2320 - viewed 891 times.)
Logged

W2DU, ex W8KHK, W4GWZ, W8VJR, W2FCY, PJ7DU. Son Rick now W8KHK.
Todd, KA1KAQ
Administrator
Member

Offline Offline

Posts: 4218


AMbassador


« Reply #2 on: January 05, 2011, 07:07:18 PM »

VERY cool story, Walt. That is indeed some interesting history, especially the work-arounds the get the job done with a successful deployment. Having spent over a decade in gov't service, I couldn't agree more about the 'KISS' approach. Unfortunately, the two seem to be at constant odds.

I share your amazement about the copper sheath-into-sphere process. Was a time this type of knowledge and skill was commonplace in most every shop of any size. Try to find it today, anywhere. There are still skilled folks out there, machinists and engineers, who continue to perform the impossible.

Thanks for sharing. And BTW, the reason you couldn't post the final photo is the limit of 3 attachments per post. You worked it out just fine. Wink
Logged

known as The Voice of Vermont in a previous life
N0WVA
Member

Offline Offline

Posts: 291


« Reply #3 on: January 05, 2011, 07:49:55 PM »

Walt,

I enjoy reading about your pioneering work that we take for granted today. Must have been exciting times back then.
Logged
W2XR
Contributing
Member
*
Offline Offline

Posts: 885



« Reply #4 on: January 05, 2011, 08:02:45 PM »

Hi Walt,

Perhaps you may recall a similar series of conversations a few years back, here on the board, pertaining to Echo I. I was fascinated as you recounted your involvement with the program, and your sharing of some of the technology that was involved with Echo.

As a small boy of 6 years old, I can vividly recall my Dad taking me (and several of my young friends) out to the night sky, hoping to catch a glimpse as the highly reflective Echo passed overhead. For a time, that was the big thing in my neighborhood and around the country, at least among the more technically inclined; to watch as Echo made its rapid pass across the night sky.

In 1960, this was pretty heady stuff. The space age was only 3 years old at that point, with the October, 1957 launch of Sputnik. Most of this bordered on the realm of science fiction, at least to those (like my Dad) who may have read about the possibilities of satellites and satellite communications as espoused by the great writer Arthur C. Clarke in the late 1940s. Had I been a radio amateur in 1957, I would have been utterly astounded and amazed, as I am sure many hams of the era were, as I listened to Sputnik transmitting in the 20 Mhz and VHF portions of the radio spectrum.

A quick glimpse of QST magazine of that era reveals the intense interest and coverage of Sputnik within the radio amateur community.

I would never imagine, as a young boy in 1960, and being well aware of Echo at that time, that I would one day be in communication with a former RCA engineer associated with the Echo program. May I state to you that I am honored to do so?

Of possible interest, the company I worked for in the 1980s was a fairly major supplier to RCA Astro of S-level (space-qualified) flight electronics hardware for the TIROS-N and DMSP satellite programs. I found that work fascinating.

73,

Bruce
Logged

Real transmitters are homebrewed with a ratchet wrench, and you have to stand up to tune them!

Arthur C. Clarke's Third Law: "Any sufficiently advanced technology is indistinguishable from magic".
W2DU
Contributing
Member
*
Offline Offline

Posts: 490

Walt, at 90, Now 92 and licensed 78 years


WWW
« Reply #5 on: January 05, 2011, 08:06:19 PM »

I was just very lucky to have been in the right place at the right time, the earliest beginning of the space age. Getting involved at that time was exhilarating, fun and challenging on every project I was associated with.

If there is interest there, I'd like to tell the strange route taken in coming up with the World's first weather satellite, TIROS 1, (Television Infra Red Observation Satellite.) My assignment on that project was the development of the entire antenna array, which radiated circular polarization from four transmitters operating simultaneously on four different frequencies.

Walt
Logged

W2DU, ex W8KHK, W4GWZ, W8VJR, W2FCY, PJ7DU. Son Rick now W8KHK.
W2XR
Contributing
Member
*
Offline Offline

Posts: 885



« Reply #6 on: January 05, 2011, 08:09:39 PM »

I was just very lucky to have been in the right place at the right time, the earliest beginning of the space age. Getting involved at that time was exhilarating, fun and challenging on every project I was associated with.

If there is interest there, I'd like to tell the strange route taken in coming up with the World's first weather satellite, TIROS 1, (Television Infra Red Observation Satellite.) My assignment on that project was the development of the entire antenna array, which radiated circular polarization from four transmitters operating simultaneously on four different frequencies.

Walt

Yes, TIROS-1 was the hatbox-shaped weather satellite, as I recall, studded with solar cells. RCA promoted it heavily in commercials when they sponsored Walt Disneys "Wonderful World of Color" television program in the early 1960s.

73,

Bruce
Logged

Real transmitters are homebrewed with a ratchet wrench, and you have to stand up to tune them!

Arthur C. Clarke's Third Law: "Any sufficiently advanced technology is indistinguishable from magic".
W2DU
Contributing
Member
*
Offline Offline

Posts: 490

Walt, at 90, Now 92 and licensed 78 years


WWW
« Reply #7 on: January 05, 2011, 08:10:07 PM »

Thank you Bruce, for those nice words. As I said earlier, I'm just one lucky guy!

Walt
Logged

W2DU, ex W8KHK, W4GWZ, W8VJR, W2FCY, PJ7DU. Son Rick now W8KHK.
w3jn
Johnny Novice
Administrator
Member

Offline Offline

Posts: 4573



« Reply #8 on: January 06, 2011, 12:38:08 AM »

Walt, there's ALWAYS interest here for ANY of your stories!!!

Thanks much for sharing.
Logged

FCC:  "The record is devoid of a demonstrated nexus between Morse code proficiency and on-the-air conduct."
WA1GFZ
Member

Offline Offline

Posts: 11152



« Reply #9 on: January 07, 2011, 10:52:49 AM »

That's a fact Bruce and John.
It is an honor to even hear your stories and know you.
Logged
W2XR
Contributing
Member
*
Offline Offline

Posts: 885



« Reply #10 on: January 07, 2011, 11:30:17 PM »

Walt,

Were you aware that the Echo satellite program also provided the astronomical reference points required to accurately locate the Russian city of Moscow geographically? This aspect of the program was certainly not highlighted (or probably made public) by NASA. The improved accuracy was sought by the U.S. military for the purpose of accurately targeting intercontinental ballistic missiles.

73,

Bruce
Logged

Real transmitters are homebrewed with a ratchet wrench, and you have to stand up to tune them!

Arthur C. Clarke's Third Law: "Any sufficiently advanced technology is indistinguishable from magic".
Bill, KD0HG
Moderator
Member

Offline Offline

Posts: 2563

304-TH - Workin' it


« Reply #11 on: January 11, 2011, 12:45:14 PM »

Here's a pertinent new story that Walt might find of interest:

Space scientists will redevelop British Telecomm's historic Goonhilly satellite station in Cornwall to allow communication with missions to Mars, it is revealed today.

The first dish, "Arthur", was built in 1962 to communicate with Telstar, which relayed the first live transatlantic TV broadcasts.

"We have plans to go one stage further and to use the antennas at Goonhilly to support space science missions to the Moon, Mars and beyond" <snip>

Story here:

http://www.theregister.co.uk/2011/01/11/goonhilly_bt/

Logged
W2DU
Contributing
Member
*
Offline Offline

Posts: 490

Walt, at 90, Now 92 and licensed 78 years


WWW
« Reply #12 on: January 11, 2011, 01:33:08 PM »

Thanks for the new story, Bill. Very interesting read indeed. Have you read my story on NASA's RELAY re its connection with TELSTAR?

Walt
Logged

W2DU, ex W8KHK, W4GWZ, W8VJR, W2FCY, PJ7DU. Son Rick now W8KHK.
Jeff W9GY
Member

Offline Offline

Posts: 257



« Reply #13 on: January 11, 2011, 02:36:20 PM »

Ah yes, Walt.  Echo was a bright object!  I certainly remember, being a Jr. HS student at the time, going out and looking at it go over.  Wow!
Logged

Jeff  W9GY Calumet, Michigan
(Copper Country)
N4LTA
Contributing
Member
*
Offline Offline

Posts: 740


« Reply #14 on: January 11, 2011, 05:41:51 PM »

I remember my father taking me outside and waiting for the Echo 1 pass. I was nine. Those were some exciting times for kids growing up.
Logged
W2DU
Contributing
Member
*
Offline Offline

Posts: 490

Walt, at 90, Now 92 and licensed 78 years


WWW
« Reply #15 on: January 11, 2011, 07:02:30 PM »

Thanks everyone for the nice responses--I'm pleased that you found the story of interest.

I must tell you that it was a heady time for me, too, not knowing at the time that everything was going to work as planned, because those things had never been done before.

Walt
Logged

W2DU, ex W8KHK, W4GWZ, W8VJR, W2FCY, PJ7DU. Son Rick now W8KHK.
DMOD
AC0OB - A Place where Thermionic Emitters Rule!
Contributing
Member
*
Offline Offline

Posts: 1180


« Reply #16 on: May 07, 2011, 11:20:59 PM »

This is interesting since Rockwell Collins had an Echo I site in NE Cedar Rapids Iowa called, "Echo Hill," now in Marion, Iowa.

There is now a new school on the site by the same name.

This is where Rockwell did RF reflections and communications experiments mainly for the benefit of the SAC.

Interestingly, there is a ham that has a house about 300 meters from the site.

Phil - AC0OB

Logged

"What kind of Koolaid do they make you drink in the Physics Department?" Charlie Epps to Dr. Larry Fleinhardt, NUMB3RS   Smiley
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.057 seconds with 18 queries.