Table of Contents

Mission STS-115

Space Vision System

Conceived 28 years ago in Canada's National Research Council laboratories and built by NEPTEC, the Space Vision System (SVS) is designed to enhance astronauts' vision in the difficult viewing conditions of space. It provides information on the exact location, orientation and motion of a specified target, helping astronauts to perform precise tasks in the extreme lighting conditions. The Space Vision System was first tested by Canadian astronaut Steve MacLean during its first space flight in 1992 (STS-52).

Today, a more robust and improved vision system is used both on the Space Shuttle and on the International Space Station (ISS) with the two Canadian robotic arms, Canadarm and Canadarm2. The SVS enables the Canadarm and the Canadarm2 to handle payloads, which are out of sight to astronauts who operate the two robot manipulators. The unit installed on the shuttle was used to connect the two first modules of the Space Station, Unity and Zarya, during the very first ISS flight in 1998 (STS-88).

The Space Vision System (Photo: CSA)

The Space Vision System uses TV cameras as sensors. These cameras monitor a pattern of special target dots placed on the object to be tracked. As the object moves, the system tracks the changing position of the dots, calculates the location and orientation of the object, and presents this information to the operator in the form of both graphical and textual cues. This information can be used to position and orient a payload using the Canadarm or the Canadarm2, or to join two objects as in the case of Space Station assembly.

The Space Vision System has many enhanced features that increase its accuracy, versatility and usefulness, making it able to operate in a wider range of lighting conditions. Frequent periods of extreme dark or bright light make it difficult for astronauts working in space to gauge the distance and speed of objects such as satellites. With the addition of improved target tracking features, the Space Vision System is able to switch from one set of targets to another when one moves out of its field of vision. The system is also capable of "losing" some targets as they become obscured, allowing the calculations to continue on the remaining targets. For some operations, this system can also overcome conditions such as the Shuttle turning or shaking, and assist in berthing manoeuvres of an object in space.

During Mission STS-115, Steve MacLean had the opportunity to use again the system he tested back in 1992. He used the Space Vision System to help install a pair of solar panels on the International Space Station, thus completing another phase of its assembly. These panels generate more electricity to run all the Station's systems, including life support, daily operations and scientific equipment. The Space Vision System is used for increasingly sophisticated tasks and helps to meet NASA's stringent requirements for precision and safety.