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Background information for Canada in Space

Canada has accomplished some remarkable achievements in space technology. Below you will find a few subjects to investigate. You may also want to explore topics relating to our school program "Space: Space Exploration".

Black Brant Rockets

The Black Brants are scientific research rockets, used to study the auroras and the upper atmosphere. They fall back to Earth. The first Black Brant I was launched at Churchill in 1959 and carried instruments weighing 100 kg to an altitude of 99 km.

Most of the sounding rockets launched from Canada were sent aloft from Churchill, Manitoba. Today, Black Brants are no longer launched from Canada, but are still used by other countries.

The payload is the cargo the rocket carries into space, (experiments, satellites, people). It is the reason for sending the rocket into space.

Since there is little oxygen in the upper atmosphere, the rocket must carry its propellants, fuel and oxidizer, with it. Propellants are a large portion of the weight of the rocket.

In liquid fuel rockets, fuel and oxidizer are pumped into the combustion chamber in the engine. This mixture is called a propellant. As the propellant burns, the exhaust gases are forced out of the nozzle at the back of the rocket, pushing the rocket forward (Newton's Third Law). Black Brants have solid fuel motors. The propellant is a rubbery mass of fuel and oxidizer. It burns along the axis of the rocket.

The Black Brant was named after a small, dark, fast flying Arctic goose.

Earth Orbits

A satellite travelling in orbit around the Earth is actually falling, just like a thrown ball, towards Earth. If the Earth were flat, the satellite would hit the ground. But the Earth's surface curves away from the satellite, leaving it in free fall. If the satellite is going at the right speed for its height above the Earth, it never hits the ground, and is said to be "in orbit". Compare this to a ball on a string that is swung overhead: too slow a velocity and the ball will fall "out of orbit".

The nearer a satellite's orbit is to Earth, the stronger the gravity pull on it. The satellite must go faster to remain in the lower orbit.

All orbits are elliptical, having two focal points. A circular orbit is a special case with both focal points in the same spot.

The plane of a satellite's orbit must pass through the centre of gravity of the Earth.

The Moon orbits the Earth at an average altitude of 400,000 km.

A satellite at a height of 36,000 km, (actually 35,786 km), takes 24 hours to circle the Earth. A satellite in this orbit, directly above the equator, going eastward as the Earth does, stays above the same point on Earth. This is the geostationary orbit. Most communications satellites are in this type of orbit.

A satellite in a polar orbit travels over Earth's poles, as the Earth turns underneath. Weather satellites and Earth observation satellites are usually in orbits of this type. These are low orbits, and the satellites travel around the Earth about 14 times a day, which keeps them viewing at about the same "time of day" for every pass. After several days, remote sensing satellites have covered almost the whole planet. Military satellites travel in very low orbits.

The Space Shuttle travels in an orbit about 160 to 320 km high, and it can be inclined at various angles to the equator, depending on the launch angle. The shuttle flight of Canada's first astronaut, Marc Garneau, in 1984, was inclined at 57E to the equator, which allowed him to see parts of Canada not normally seen by shuttle crews. They usually travel in a more equatorial orbit.

Some Russian communications satellites were put into elliptical orbit at an angle to the equator. This allowed them to travel slowly high over northern Russia for a large part of their orbit. As one was sinking into the horizon, a second would be coming into view to continue the communication relay.

Alouette - a scientific satellite

The Alouette, a scientific satellite, was Canada's first, launched in 1962.

With it, we became the third country in the world to have a satellite in space, designed and built by Canadians.

Its purpose was to probe the ionosphere, (the electrically charged upper atmosphere), from above, while instruments from the ground measured this atmospheric layer from below. The ionosphere, usually capable of reflecting radio waves, sometimes causes blackouts in radio transmissions, especially AM radio.

The orbit of the Alouette was circular, 1000 km above the Earth, inclined at 80o to the equator.

It was launched by NASA on a Thor-Agena rocket. This rocket carried a crossed flags insignia, symbolizing the joint venture.

It operated for a decade, and with it Canadian scientists became leaders in upper atmosphere research.

John Chapman was the head of the Alouette program. He became known as the architect of the early Canadian Space Programme, for this and subsequent pioneering projects.

STEM Technology

The problem

    The Alouette satellite required a large antenna. How were the engineers going to get this antenna into space? The whole package, satellite and antenna, had to fit tightly within the nose cone of a rocket.

The answer

    The STEM, invented by National Research Council engineer George Klein, modified for the Alouette satellite.

The STEM was an antenna consisting of a flat strip of steel, about 10 centimetres across, wound on a reel. (Imagine a carpenter's metal spiral measuring tape.) This strip had been heat-treated, so that when it unwound, it snapped into a long tube, which was extremely strong. STEM stands for Storable, Tubular, Extendible Member.

STEMs were used on many of the early satellites and manned space capsules.

Alouette had four STEMs, two 22.5 metres long and two 11 metres long. (Two stems formed one antenna.)

STEM antennas were produced by Spar Aerospace Limited of Canada, now a major developer and manufacturer of space hardware.

STEMs were used as booms or masts as well as antennas; one use was to push out the Hermes solar panels.

There are several examples in the Canada in Space: Destination Earth exhibit, at the Museum.

How communications satellites work.

Communications satellites, comsats for short, relay all kinds of messages around the world, often between areas so far apart that an ordinary wire link-up would be very difficult or impossible. A comsat is a relay station that receives from and transmits to its "footprint" area on Earth.

Most comsats use geostationary orbit, so that they stay above the same point on Earth. They make it possible to watch live transmissions of events like the Olympics. They link countries' telephone systems directly and cheaply. Much financial business is conducted at high speed via comsats, often in the form of computer data or pictures of documents. Comsats are also used to transmit educational material to remote areas.

The following explanations relate to systems using geo-stationary satellites.

Telephone transmission:

The voice is converted into analog electrical signals that travel along wires to local and central exchanges, then to a ground station by wire or microwave links. The ground station transfers the signals to digital data and beams them to a comsat. The comsat then sends the signals to a receiving ground station. The signals travel through wires to exchanges to the destination telephone. Along its path the signal will have been amplified and processed several times.

Direct broadcasting satellites:

Small dish antennas on buildings or in backyards can receive comsat signals directly if they are within range of a satellite "footprint" and tuned appropriately. This is called direct satellite broadcasting, and means that TV can be transmitted cheaply to a wide area without requiring a large number of ground stations. The dishes must aim directly at the satellite location in the sky (35,800 km) above the equator.

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Anik A- a communications satellite (1972)

In 1967, Dr. John Chapman, the architect of the Canadian Space Programme, submitted a report to the government of Canada that changed the direction of development from scientific satellites to communication satellites. Scientists were learning that the blackouts in radio transmissions, caused by the ionosphere, were so severe that only satellites using higher frequencies could overcome them. The report recommended using communications and surveying satellites to help solve the ever present Canadian challenges of few people spread far apart in a vast land with a harsh climate.

Anik A was Canada's first communications satellite, launched by NASA on a Thor- Delta rocket in November, 1972. It was placed in geostationary orbit about 35,800 km above the equator. From there it could beam television programmes in a "footprint" that covered all of Canada.

It effectively linked the frontiers of Canada together just as the railway had almost 100 years before.

The earth stations used with the satellite had large antennas, 8 metres in diameter. Receiving dishes of this size were necessary to pick up the weak signals coming from the satellite. The launch of Anik A made Canada the first country to have its own geostationary satellite for domestic communications.

Two Anik E's are the latest satellites in the series, launched in 1991.

Anik means "brother" in the Inuit language.

Hermes - an experimental communications satellite (1976)

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, conducting experiments.

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 T.V.).

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.

In Greek mythology, Hermes was the messenger of the gods.

Anik E - a communications satellite (1991)

The Anik series of satellites provides communications for Canadians. The active satellites are now two Anik E's, E1 and E2.

They provide communications services in both the 6/4 GHz band (C) and the 14/12 Ghz (Ku) band.

They were built by Spar Aerospace, launched by the European Space Agency's Ariane rocket in 1991, and are expected to last for 10 years.

They are the largest, heaviest and most powerful communications satellites in the world.

Anik E2 gave Telesat engineers problems when, in April 1991, the C band antenna failed to open. The command to deploy the antenna triggers explosive charges that fire pins through the cables which are wrapped around the whole circumference of the satellite. This releases the bundled equipment. The entire assembly is supposed to unfold like a flower once the straps are severed. At first the engineers tried a shake and bake approach to free the antenna, but no luck.

After a series of increasingly risky manoeuvres, which involved spinning the satellite, the antenna finally loosened. It appeared that the thermal blanket covering the satellite had dislodged and prevented the antenna from opening. The satellite could not be completely tested in the thermal vacuum chamber of David Florida Lab prior to flight, as it was too big to fit, with its antennae fully extended. Telesat, the owner/operator of the satellite, received two awards for this rescue, one of which was the first ever Space Recovery Prize from La Réunion Spatiale, an International Space Risk Insurance Group.

The two operating Anik Es now do the work of four earlier satellites, Anik C1 and C2 and Anik D1 and D2. In January, 1994, both Anik E1 and Anik E2 suffered system failures as a result of a solar storm. Telesat had Anik E1 back in operation within a few hours but Anik E2 was not restored until June of that year.

David Florida Laboratory

Satellites are subjected to extremely harsh conditions. They experience tremendous vibrational stress during a launch. If something breaks during the launch, it cannot be fixed once in orbit. In space, they are exposed to vacuum and extreme temperature ranges. This is the reason why all satellites are put through intensive testing before they are sent into orbit.

The David Florida Laboratory near Ottawa has been providing this testing service to Canadian and international space communities for two decades. It is one of the world's advanced aerospace testing facilities.

The Thermal Vacuum Facility, simulates the temperature and vacuum of space, cycling through the extremes of cold and heat to ensure that space hardware will perform under these conditions.

This facility also contains a thermal vacuum spin machine to test a satellite's performance while spinning in space.

The Vibration Test Facility shakes satellites to ensure that they can withstand the jarring vibration and shock of the launch. Radio Frequency Testing is performed in the anechoic (reflection free) chambers which duplicate the conditions in space.

The laboratory also provides a clean controlled environment for satellite assembly.

The DFL was named in honour of one of Canada's space pioneers. David Florida was manager of the team that built the ISIS satellite. The lab was built initially to support the development of the Hermes communications satellite. It also provided support for the Anik communication satellite series, the Canadarm, Brasilsat, the ESA's Olympus communications satellite, RADARSAT, MSAT and it will test the Mobile Servicing System, Canada's contribution to the International Space Station.

Canadarm

This Remote Manipulator System was designed and built in Canada by Spar Aerospace, for the U.S. Space Shuttle.

It is a robotic arm that allows astronauts to release or retrieve satellites in space. It also allows astronauts to work remotely in the cargo bay, from the safety of the flight deck. At times it has served as a platform from which astronauts can make repairs to satellites outside the cargo bay, and has even dislodged ice from a shuttle vent.

The arm is operated by two hand controls on the flight deck. Video cameras at the "elbow" and "wrist" assist the operator in the task.

Canada paid for the design and production of the first arm ($100 million) and NASA bought three others ($25 million each) to outfit the shuttle fleet, plus a replacement for the arm on the Challenger, lost in 1986.

The arm's maximum payload is about the size and weight of a loaded school bus, but on Earth it cannot even support its own weight.

Each is expected to last for 100 missions.

Canadian engineers are designing and building new versions of the arm for the International Space Station. The new arm will be the key element in assembling modules as they arrive in space. The new device is called the Mobile Servicing System.

As an analogy, one could say that the Canadarm has bones of graphite fibre, nerves of wire and motors for muscles. Instead of a hand, the Canadarm has an end effector composed of three snare wires that entrap the grapple knob on a satellite.

RADARSAT - an Earth Sensing satellite

RADARSAT, Canada's newest satellite was launched in November, 1995. Using a microwave beam, which reflects off the ground back to the satellite, it is able to see through clouds, and in the dark. This is a very useful technology in Northern Canada, which is often in darkness and covered with clouds.

SAR, Synthetic Aperture Radar, the heart of RADARSAT, creates many radar images of the Earth. Radar signals sent at an oblique angle, bounce away from the satellite if they hit smooth surfaces, so water appears dark. From rough surfaces, radar signals bounce back to the satellite, so buildings or surface roughness, appear bright.

RADARSAT, in polar orbit, makes 14 orbits a day, always travelling along the sunrise, sunset line, and covers the entire Arctic every 24 hours and most of Canada every 72 hours. It monitors and maps renewable resources for the agricultural and forestry industries, making observations of soil moisture and plant conditions. It also monitors the movement of ships and their tracks through ice and measures ocean winds and waves.

One of the main uses of SAR is monitoring ice formation off Canadian coasts. It can discriminate between first year ice and multi-year formations, to make ice forecasts, thus showing ships the best paths to take.