| OTTAWA
| March
20, 2009 — A
massive cloud of space debris could damage or destroy two of Canada's
most important observation satellites, says a Canadian space
official. The debris, caused by an earlier crash between two satellites, spans
1,500 kilometres in altitude, says Robert
Saint-Jean, satellite manager at the Canadian Space Agency. The Canadian
satellites, Radarsat-1 and Radarsat-2, pass through the orbit
of the debris multiple times every day.
The orbit of the debris starts around 500 kilometres above
the Earth's surface and stretches to approximately 2,000 kilometres
in altitude.
"There is a very high risk for the two satellites,” says
Saint-Jean.
The collision that caused the debris took place on Feb. 10 between
the communications satellites Iridium 33 and Cosmos 255, owned by the
United States and Russia, respectively.
It created more than 500 measurable chunks of debris, each bigger
than a tennis ball, and millions of smaller pieces of junk, which can’t
be tracked. The collision caused debris to fly into two intersecting
orbits.
Debris in space travels at speeds of eight to nine kilometres per second;
the average bullet travels at speeds of one kilometre per second.
Radarsat-1 and Radarsat-2 have a polar orbit, which means they circle
the earth around the North Pole at 798 kilometres in altitude.
They make 14 rotations around the earth a day and collect data. This
allows Canada to monitor ocean, land and ice development, which is used
to manage resources and protect the environment.
The amount of energy contained in a single fleck of paint is enough
to blast a hole through a windshield, says Ken Tapping, an astronomer
with the Herztberg Institute of Astrophysics at Canada's National Research
Council.
“Even very small things produce very large results,” he
says.
This creates a problem because only items larger than 10 centimetres
(about the size of a tennis ball) can be tracked. The millions of
smaller pieces of debris are the biggest concern, says Tapping, because
there is no way to tell if they're in a satellite’s path.
 |
| Space debris could bring down two multi-million
dollar Canadian satellites. |
Should a part of either Radarsat satellite be damaged, Saint-Jean says
repair would not be possible. If an intregal part were to break or be
damged, the satellite would have to be replaced. The government has
already invested almost a billion dollars in the Radarsat satellites.
You break it, you buy it
Under international law the country that is liable for creating the
debris must cover the cost of the damage the debris causes to other objects
in space, says Ram Jakhu, an expert in space law at McGill University.
But the country that owns the damaged satellite or shuttle must prove
where the debris came from.
This is problematic because Canada relies on the U.S. to
track the debris and to warn of impending collision, he says.
“There should be an international consortium of monitoring,” says
Jakhu. “Information is power.”
Canada also relies on the U.S. for information on when and how
to move the satellite to avoid debris, meaning it is at "the mercy
of other states,” he says.
Stratcom, a branch of the U.S. Air Force, monitors space debris. In
the event of collisions, it informs the North American Aerospace Defense
Command (NORAD), which passes the information on to the Canadian Space
Agency or MacDonald, Dettwiler and Associates Ltd., the company that
built and operates Radarsat-2.
Moving a satellite to avoid a collision is a very complicated process,
says Saint-Jean.
“It’s not like in the movies,” he says. “You
can’t just tell it to move a couple of feet to the right. That’s
only in fiction. It takes a couple of days.
“Collisions are a matter of probabilities. It [the Feb. 10
collision] wasn’t even on their top 10 list.”
Space junk piling up
The collision did highlight the growing concern among the space community
over space junk, says Tapping. In mid-March, two astronauts
and a cosmonaut were evacuated from the International Space Station
to an escape pod over fears of a collision with wayward debris.
 |
| Space junk almost forced astronauts to abandon
the International Space Station in mid-March. |
Humans have been polluting space since the USSR’s launch
of Sputnik in 1957.
Shuttles and satellites that take off or are decommissioned leave debris,
Tapping says.
There is also a risk from objects that collide or are purposefully
destroyed, such as the Chinese satellite that was blown up this past
January so China could test its anti-missile defence system.
The collision of the two satellites in early February just emphasized
the issue, says Tapping.
“We’ve been absolutely irresponsible about the way we’ve
been using space,” says Tapping. “It’s not a matter
of going at it with a catcher’s mitt or a big net. The best we
can hope for is it [all the debris] will re-enter the atmosphere in
the next 50 to 100 years.” 
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