Table of Contents

Did you know...

Question 1

That skeletons are only required on Earth?

On Earth, muscles and bones develop in response to the environmental stress we put on them as we go about our daily lives. The major contributor to our environment on Earth is gravity. The force of gravity pulling us towards the surface of the Earth places strain on every part of our bodies both inside and outside. In order to remain upright and to protect our vital organs, land animals, like human beings need a strong skeleton.

Being in space takes a great load off our body's systems. In the microgravity of space, and in bodies of water where we do not feel the bulk of the force of gravity, skeletal bones do not have to support the weight of the body. As a result, living organisms like fish have evolved in a way different to land animals.

Fish still have bones to protect vital organs and to act as support for appendages, but the massive bone structures that are typical in land animals are not present. In space, humans no longer need heavy, weight-bearing bones (like the hip bone or tibia) since the force of gravity is no longer a concern.

The human brain is quite extraordinary. Within the first day or two in space, the brain adapts to a microgravity environment. Part of this adaptation results in the body beginning the process of shedding its skeleton. Every time an astronaut urinates in space, calcium, a crucial bone-building element, is lost. In fact they can lose up to 2% of their bone mass each month thus reducing the size and strength of their bones.

People suffering from muscular dystrophy and osteoporosis experience a similar loss of bone mass. In microgravity, the process of bone loss happens up to 10 times faster than on Earth.

Although the loss of bone mass is not worrisome for astronauts during space missions, when they don't have to rely on a strong skeleton to support their mass, it becomes a major concern when they return to the gravity environment of the surface of Earth. The molecular mechanism for this loss is not known. Space research into this phenomenon, with its unique microgravity environment, may one day result in treatments or even cures for the crippling diseases that affect almost 1.5 million Canadians.

Question 2

That Canadarm2 will NEVER come back to Earth?

Canadarm2, or the Canadian Robotic Arm is the only space robotic system that can assemble pieces of the International Space Station. Built for the Canadian Space Agency, this robot is 17 meters long and has a mass of about 1100 kg.

The length of this robot is such that it could not fit into the Shuttle's cargo bay without being folded.

Except for the shoulder, wrist and elbow joints, the arm had to be rigid during the power-packed ride to the International Space Station so that the tremendous vibration of the launch would not break the long boom sections of the arm. Once on orbit, the robot had to be unfolded, its meter-long bolts removed and new expandable bolts put in place allowing the robot to "stretch" its arms straight. Canadian astronaut Chris Hadfield was the lead EVA (extra-vehicular activity) Astronaut during three space walks to unfold, lock and test the Canadarm 2.

The arm itself sits in space permanently attached to the International Space Station. This robot is exposed to extremes of temperature every 45 minutes ranging from -160 degrees Celsius to +240 degrees Celsius. Imagine what would happen to the body of your car under these conditions!

There are no body shops in space. Under the hostile conditions in which this technology has to work, malfunctions are possible.

To help overcome downtime on orbit, Canadian engineers built the arm with redundant or backup systems. In the event of a malfunction, and should the back up systems not work, on-orbit astronauts take on the role of robot mechanic, changing the offending systems. To date, an elbow joint has been replaced.

Question 3

That bodies in microgravity don't float? They fall!

Almost all pictures of astronauts, satellites and space stations in space have one thing in common: they appear to be floating.

A common misconception is that when a body is sent to space, it experiences a zero-gravity environment. This is false.

Gravity does not disappear when you get to orbit. A space shuttle at 300km experiences almost the same force of attraction to the center of the Earth as a body standing on the surface of the planet.

Bodies in space fall toward the Earth due to the force of gravity exerted on them. So how is it that astronauts, and spacecraft remain in space even though they are constantly falling toward the Earth?

If you were to go the top of a 300 km tall mountain (if one existed) and dropped a cannon ball, the gravitational attraction between the cannon ball and Earth would pull them together. Put another way, the ball would fall to the ground (Figure 1).

If you fired a cannon ball horizontally from the top of the mountain, the ball would travel a considerable distance but would also fall toward Earth and eventually hit the surface. Earth is approximately spherical, so if the cannon ball is moving very fast, Earth will begin to curve away from the ball as the ball is drawn to Earth. The faster the ball goes the further around Earth it gets before hitting the ground.

If you could shoot a cannon ball horizontally from an altitude of 300 km with a velocity of about 7.5 km/s (27,000 km/hr), the ball would follow a path that is approximately circular with respect to the centre of Earth, moving away and then falling back at every point on its path. This path is called an "orbit" (see Figure 2).

The International Space Station orbits the Earth at 28,000 km/hour. Like the cannon ball, the station falls toward the Earth. And so the station stays in orbit because the Earth, which is round, curves away from it as it falls.

An astronaut inside the space station is traveling at the same rate as the spacecraft. In other words, both the person and the station are falling at the same rate of acceleration. As a result, the astronaut appears to be floating.

Question 4

That stars don't twinkle?

The Earth's atmosphere is a wonderful thing. It not only gives air to breathe, and helps moderate temperatures so that we can live almost anywhere on the planet, it also protects us from objects in space such as meteoroids and cosmic rays.

Our atmosphere does have a few drawbacks. One of the most noticeable is that it distorts our view of the cosmos so that stars appear to twinkle.

Twinkling is, to the astronomical community, known as stellar scintillation and is caused by airflow in the atmosphere. Because stars are very far away, they appear as points of light even in a telescope. It only takes a very small change in the properties of the atmosphere between the telescope and the star to change the path of the starlight. t The eye interprets the change in brightness of a star as twinkling (see Stellar Scintillation Figure).

To reduce the effect of the motion of the atmosphere, astronomers tend to build Earth-bound telescopes on the top of tall mountains, where there is less air between the telescope and the star.

The Canada-France-Hawaii Telescope is on top of Mauna Kea in Hawaii, 4,200 meters above sea level. At this height only 60% of the atmosphere remains between the lens of the telescope and the void of space.

Bright objects that look like stars but do not twinkle are planets, such as Venus, Mars, Jupiter or Saturn. In a telescope, planets are not points of light like stars so the effect of the atmosphere on their brightness is greatly reduced.

To eliminate the affects of the atmosphere astronomers have designed space-based telescopes. Canada has launched its own satellite telescope called MOST (Microvariability and Oscillations of STars), capable of measuring the ages of stars in our galaxy and perhaps even unlocking some of the mysteries of the universe itself. You can read all of the details about MOST, Canada's suitcase-sized astronomical powerhouse at:
www.asc-csa.gc.ca/eng/satellites/most.asp.

Question 5

That the place most similar to Mars on Earth is located in Canada?

Mars is a cold, dry place, where ferocious winds blow creating long-lasting sand storms. The reddish brown surface is covered in impact craters in the Southern Hemisphere but is relatively smooth in the North. The force of gravity on Mars is about one third that of Earth and the atmosphere is thin and filled primarily with Carbon Dioxide.

Devon Island, Nunavut in the high Arctic, the place on our planet that is most like Mars, is the home of the Haughton meteorite impact crater. It was formed about 23 million years ago by a meteorite that left what is today a hole with a 20 km diameter. It is one of the highest-latitude terrestrial impact craters on Earth (75°22'N, 89°41'W) and lies in a polar desert environment. It is unique in that it is the only crater known to lie in such an environment.

A number of groups interested in exploring Mars needed to find somewhere on Earth to test their systems and instruments to see how they might operate on the red planet. The landscape of the Haughton crater is similar to what one might expect on Mars. During the summer months, researchers travel to the Canadian Arctic to live in a simulated Mars-base environment - not too far from your own back yard! For more information about the Mars analogue environment go to: http://resources.yesican.yorku.ca/trek/mars/hmp99.htm

Question 6

That you could not drink the rain on Venus?

Fortunately the rain on Venus does not reach its surface.

Venus is almost a twin to Earth in size and gravity. However, that is where the similarity stops. The atmosphere on Venus is very different from ours. It is comprised mostly of carbon dioxide. Water vapour clouds found in Earth's atmosphere are replaced with clouds made of sulfuric acid drops. These clouds are so dense that from space, using visible light we could not see through them to the surface of Venus.

The diagram to the right shows the composition of the atmosphere of Venus.

The atmosphere on Venus is very thick - with atmospheric pressure about 90 times that of Earth. Although we would not feel any heavier if we were to walk there, the atmospheric pressure would crush our space suits.

The temperature is the main reason the rain never reaches the surface of the planet. The surface temperature of Venus is about 220 degrees Celsius. As the sulfuric acid drops fall towards, they heat up and evaporate. It is very hot because both the carbon dioxide and the sulfuric acid capture heat from the sun and distribute it around the planet. Venus does not cool off at night.

Sulfuric acid is very useful on Earth (in small quantities). It is used to dissolve and etch metals, used in batteries as an electrolyte and has applications from dyes to toilet bowl cleaners. However, it is very unpleasant should you get it on your skin or inhale any of the vapour.

Question 7

That a magnetic force field surrounds the Earth and protects us from very small space invaders?

No, the space invaders are not life forms from another part of the galaxy! They are, in fact, particles from the sun. These particles are part of the sun itself that have been ejected during solar storms and come to us on the solar wind. Great solar prominences are usually the origins of these particles. They travel very quickly through space, and sometimes cause major disruptions in the atmosphere and on the surface of Earth. This is where the Earth's magnetic field protects us.

The Earth's magnetic field looks similar to that of a bar magnet. Other magnetic fields in our solar system (mainly from the sun) cause the pattern to flatten on the sunward side and expand into a large comet-like tail on the other side (see diagram).

A major portion of this solar wind goes around Earth and continues out into the solar system because moving charged particles are deflected by magnetic fields. Some of the particles manage to penetrate this magnetic shield, usually around the magnetic poles, and come crashing into the atmosphere. Even though our atmosphere is quite thin, these particles are stopped at high altitudes (80 to 100 km). This interaction with the atmosphere is what causes the Aurora Borealis (Northern Lights) and the Aurora Australis (Southern Lights).

We are very fortunate to have the magnetic field. Were it missing, the solar wind would slowly wear away the atmosphere (similar to the fate of the atmosphere on Mars).

We are protected on the Earth's surface and in low Earth orbit (where the Shuttle and the International Space Station are in orbit) but as we move further away from the Earth - out to 37,000 km (where communications satellites orbit), the protection is greatly reduced and the satellites are in danger of failure during a large solar storm. In 1994 two Canadian communications satellites were temporarily affected by a solar storm. Both satellites were eventually returned to service.

Question 8

That some satellites can capture the "eye" of a hurricane?

Hurricanes and typhoons are very large-scale destructive storms caused by the same weather conditions. Large areas of warm air over the ocean (Atlantic and North Eastern Pacific for hurricanes and North Western Pacific for typhoons) rise, and as they do they begin to rotate (cyclonic or counter-clockwise rotation in the Northern Hemisphere). Moved by winds that blow from the east to the west, these storms track westward and poleward until they run into a land mass. At this point, they start losing their energy and eventually blow themselves out.

From space, hurricanes and typhoons are wondrous sights. The first figure is of supertyphoon Winnie photographed in visible light during the flight of STS-85 (with Canadian Astronaut Bjarni Tryggvason on board). In the centre of these storms, whose winds can reach 130 - 140 km/hr is a region of relative calm and where there are few clouds - the eye (dark region in centre of picture).

The clouds of hurricanes prevent us from seeing the effect the winds have on the ground, from space. The Canadian Earth Observation satellite RADARSAT, uses microwaves that penetrate the clouds and reflect back from the surface of the ocean. The second picture is that of Hurricane Lili as seen by RADARSAT. The picture shows Hurricane Lili just north and west of Jamaica with the eye just east of the Cayman Islands.

The amount of microwaves reflected depends on the roughness of the surface. For the ocean surface, the roughness, as measured by RADARSAT, is influenced primarily by the surface wind speed. In this picture the lightest shades are the regions where the ocean surface is the roughest. The eye of the hurricane appears darker than its surrounding area because the wind speed at the centre of the hurricane is lower.

By using RADARSAT imagery, meteorologists can examine the large-scale characteristics of hurricanes and typhoons as they influence the surface of the ocean. This research will improve our understanding of these dangerous storms.