JocelynTait  
  Electrical and Computer  
Engineer 
   
 
Photo
62K
 Hermes Icon Hermes 
 
Home
Education
Experience
Goals
Software
Patents
Designs
Publications
Site
About
Contact
 		  Hermes in orbit, with solar sails deployed 
In January 1976, the Communications Technology Satellite (CTS), later known as Hermes, was launched. It was a significant milestone in Canadian space history. It also represents a major achievement for CRC. Hermes' innovations set a new course for domestic satellite communications systems in Canada and have had implications throughout the world. Experiments with the satellite paved the way for many now-common commercial services, including: 
  • tele-education
  • satellite news gathering (SNG)
  • direct broadcasting by satellite to individual homes (DBS)
  • integrated digital telecommunications. 
One of the primary objectives of Hermes was to test a system that used the super high frequency 14/12 GHz bands. This means that transmission of signals from Earth is about 14 thousand million cycles per second (14 gigahertz) and transmission back to Earth is about 12 GHz. These frequencies are reserved for satellite communications, unlike the 6/4 GHz bands used by previous satellites and by the ground networks that carry telephone and other telecommunications traffic. By using 14/12 GHz that did not interfere with ground-based transmissions, Hermes could transmit at high power to small earth stations with dish antennas measuring less than one metre wide, right in the centre of town. 
The Hermes design had other technical innovations used on later spacecraft. It was powered by solar cells attached to flexible solar panels. The delicate sails, with 27,000 solar cells, folded like an accordion during launch and were unfurled only when in orbit. For maximum efficiency, an advanced tracking mechanism maintained the solar panels at right angles to the sun's rays. Hermes also had an improved stabilization system that kept the satellite fixed with its antennas pointing earthward within a small margin of error. 
Hermes had a design life of two years, but Canada and the United States were able to conduct experiments for almost twice that time - from April 1976 to November 1979, when the satellite finally stopped functioning. Important technical experiments included digital TV transmission and a technique to send satellites bursts of information timed so accurately that they arrive within a few billionths of a second from one another.  This permits maximum efficiency in the satellite since it can be accessed from multiple points in lightning-quick succession. Furthermore, different kinds of telecommunications information -- voice, data and image -- can be integrated within a single burst. 
Social experiments explored the potential uses of this gigaherz technology to better serve residents of rural and remote areas in the fields of health, education, broadcasting and inter-community communications. Despite the fact that some of these applications are carried by terrestrial networks the Hermes experiments were undoubtedly the catalyst for these services. During its lifetime, Hermes was the most powerful non-military communications satellite ever put into space.
Solar Sail Test 
 Hermes - an experimental communications satellite 
  •     Hermes was the first high powered satellite in orbit, meant to be the prototype for direct broadcast satellites transmitting television directly to individual homes.
  •     The Hermes satellite pioneered development of the 14/12 GHz frequency bands of the radio spectrum, bands which are not shared by terrestrial systems and therefore not affected by interference.
  •     Hermes' unusually high transmitting power meant that small, low-tech satellite dish antennae could receive the signals, eliminating the need for large expensive Earth stations.
  •     Hermes was a joint project of the Department of Communications and NASA.  Each country used the satellite on alternate days.
  •     Canadian experimenters used Hermes for tele-education, (students in remote villages could tune in and talk back), native broadcasting, (allowing communities to create their programmes in their own languages), tele-health, (using the satellite to bring medical experts to the bedside of patients far away), and tele-conferencing, (two way TV).
  •    Hermes had large solar panels that were folded like an accordion for launch, and then deployed in orbit. 

    •  
  • An Emmy was presented to Canada's Department of Communications for its role in pioneering the high frequencies used on the Hermes satellite.
 
 
 
 
Chronology  Hermes in Orbit
   
1969 
     Influenced by the Chapman Report, the federal government creates the Department of Communications, as well as Telesat Canada.  DRTE staff, buildings, resources and programs are transferred to the new Department, to become its research branch, under the name Communications Research Centre (CRC). 

1972 
     The David Florida Laboratory opens in Ottawa, first used to build the Communications Technology Satellite. The laboratory has   become a world-class facility to build and test spacecraft. It became a part of the Canadian Space Agency, when it was created in 1989. 

1973 
     In October, CRC and RCA agree to build a field effect transistor amplifier that will fly on the Hermes satellite. The contract is  completed for an American company ahead of the May 1975 deadline. 

1976 
     The Communications Technology Satellite (CTS), later christened Hermes, is launched on January 17.  Designed for a two-year life, it is used for extensive experiments until November 1979.  Hermes is the first to operate in the Ku band.  In 1987, the Department of Communications and NASA win an EMMY for their role in developing Ku band technology.
 
  CTS 
Hermes robed in gold.The large solar panels on the Communications Technology Satellite (CTS) indicate a high powered spacecraft. The communications payload included a 200 Watt TWT transmitter operating at 12 GHz. NASA's Lewis Research Center provided the high power communications payload for the Canadian satellite. The project started out with the name "Cooperative Applications Satellite C" and was a joint effort between the Canadian Department of Communications and NASA. Canada designed and built the spacecraft, NASA tested, launched and operated it, and the European Space Agency provided one of the low power TWTs and some other items. The Canadians later renamed the spacecraft "Hermes." 
The high power transmitter provided 10 to 20 times the broadcast power of typical communications satellites of that era. With more power transmitted by the satellite, it was possible to use smaller and cheaper ground stations thus paving the way for applications such as direct broadcast television. 
The spacecraft bus was around 1.8 m in diameter and 1.9 m high. With the solar panels extended, it was 16.5 m long. The solar panels provided 1360 Watts of electrical power at the beginning of life. The spacecraft weighed around 350 kg. It was launched on January 17, 1976 and was operated until October 1979. 
Images of the Communications Research Council satellite, Hermes, are provided by, and with the permission of NASA. 
This description of the satellite is provided by, and with the permission of the author, Daniel R. Glover.   <Daniel.R.Glover@lerc.nasa.gov> 
The source for this material may be found at  http://sulu.lerc.nasa.gov/dglover/cts.html