Into OrbiT

The Space System Challenge

Because remote systems operate thousands of miles away from Earth’s surface and are rarely accessible once launched and in orbit, satellites must be reliable and self-sufficient. The high cost of putting a satellite into orbit means that it may have to operate for a decade or more, performing functions such as relaying communications, transmitting precision navigation signals, monitoring weather conditions, pinpointing activities on our planet, providing strategic warning, or exploring the solar system. The types of services spacecraft provide are so critical that there is little room for error or downtime in their operation.

GPS

GPS

Space systems rely on miniaturization techniques, innovative materials, and computer technology to enhance their performance. To get the most out of a limited payload, structures must be light and strong, electronics must be microminiaturized and densely packed, and optical and radio-frequency devices must be built with great precision. That typically means a compact package that may have more than 200,000 parts. These parts, which may include deployable devices with intricate mechanisms, must operate reliably after being subjected to the shock, vibration, and acceleration of launch. Power consumption must be kept to a minimum, and the entire spacecraft must be able to pass unaffected through temperatures ranging from the intense cold of Earth’s shadow to the radiation and intense heat of the sun in the vacuum of space.

Space projects are unforgiving of neglect or human error, particularly when it comes to engineering. Their real-time performance cannot be tested fully before they are sent into space because the space and launch environment cannot be fully simulated here on Earth. An aircraft like the B-2 is tested very carefully for a year or more before it becomes operational; but a space booster like the Titan IV rocket carrying a military satellite the size of a school bus becomes operational the first time it flies. All systems must work the first time—and every time—throughout a satellite’s working life.

Today the majority of payloads are unmanned and carried into space by expendable boosters, each of which has a demanding task complicated by many issues and conditions. The booster is unable to return to Earth if something goes wrong. During flight its structure is highly stressed by launch loads and its rocket engines operate at very high temperatures. As the booster ascends through Earth’s atmosphere it endures an enormous range of aerodynamic conditions. Its guidance system must operate from the crawl of liftoff to the hypersonic speed of orbit injection with pinpoint accuracy. All information to and from the booster rocket must be carried by communication links, and the rocket’s payload must be released without human intervention.

Careful technical oversight is the only way to ensure that the system will operate the first time and throughout the mission, which might last a decade or more. Technical oversight requires the skills to get the highest performance levels out of each item as well as the modeling and simulation capabilities to determine how variations in individual components affect the performance of the entire system.

Success in space systems results from dedication to detail, repeated testing, and careful checking—up to the final minutes before launch—to find and fix any potential problems. The technical skills needed to successfully master space systems require a high level of engineering talent, study, and training.