Space junk hits Canada's robotic arm on the International Space Station

A "lucky strike" by a piece of orbiting debris has punched a hole in the robotic arm that is Canada's most famous technical contribution to the International Space Station.

The Canada Space Agency reported in a May 28 release that the puncture on a boom segment of the 20-year-old Canadarm2 was noticed during a routine maintenance inspection on May 12.

"The damage is limited to a small section of the arm boom and thermal blanket," the release stated. "A hole approximately 5mm in diameter is visible."

The agency noted that further inspection and assessment by NASA and the CSA determined that the hole will not affect the 17-metre-long arm's performance.

Near-term robotic tasks will continue as scheduled, the CSA said, as it completes the damage analysis with NASA. The Canadarm2 is scheduled to assist Dextre, Canada's sophisticated exterior "handyman" robot on the ISS, to replace a malfunctioning power switchbox, according to the agency.

The ISS, an international collaborative scientific space venture—with the U.S., Russia, Canada, Japan, and Europe's space agencies contributing—has been in low Earth orbit (400 kilometres) since 1998, saw its first human inhabitants in November 2000, and orbits the planet 15 times a day.

Canadian household names such as Marc Garneau, Julie Payette, and Chris Hadfield are some of the astronauts who have travelled to the ISS and stayed for varying lengths of time.

More than 23,000 pieces of space junk, or orbital debris, that are the size of a softball or larger are tracked nonstop by NASA to prevent collisions with the ISS and satellites, according to the CSA statement.

NASA says that the U.S. Department of Defense’s global Space Surveillance Network (SSN) keeps tabs on 27,000 such potential hazards but that many smaller pieces of junk—staggeringly, up to 100 million or more that are too small to track and can be as small as a fleck of paint—are orbiting the planet at speeds of up to 25,000 kilometres per hour (or seven kilometres per second) in low Earth orbit. The ISS travels at the same speed.

NASA supplied the following information about the sizes of orbiting debris and their potential to damage human-run spacecraft and robotic missions.

"There are half a million pieces of debris the size of a marble or larger (up to 0.4 inches, or 1 centimeter) or larger, and approximately 100 million pieces of debris about .04 inches (or one millimeter) and larger. There is even more smaller micrometer-sized (0.000039 of an inch in diameter) debris.

"Even tiny paint flecks can damage a spacecraft when traveling at these velocities. A number of space shuttle windows were replaced because of damage caused by material that was analyzed and shown to be paint flecks. In fact, millimeter-sized orbital debris represents the highest mission-ending risk to most robotic spacecraft operating in low Earth orbit."

In its more than 20-year history, the ISS has had to take "avoidance" manoeuvres 26 times because of what NASA terms a "possible conjunction" with space debris, according to NASA page editor Mark Garcia.

The Canadarm2 is the second Canadian robotic-arm contribution to space exploration. The first, the acclaimed Canadarm, was a workhorse for the U.S. space-shuttle fleet for three decades, from 1981 to 2011.