The Sky is Falling! The Sky is Falling! A Brief Primer on the Problem of Space Debris

Since 1957, the near-earth population of trackable space objects has grown from 1 to over 19,000. These objects are typically softball size or larger.  Of these 19,000+ trackable objects, only several hundred are operational spacecraft. The remainder are pieces of space junk, that is, objects which no longer serve any useful purpose. Some of these objects are fragments from explosions while others are from the breakup of satellites or rocket boosters. In addition to the trackable objects, there are several hundred thousand objects the size of marbles and several million objects the size of sand grains.

As a result, all spacecraft that operate in low-earth-orbit (such as the International Space Station) are subject to high-speed impacts by space junk, which is also called ‘space debris’ or ‘orbital debris’.  The threat of damage from high-speed orbital debris particle impacts has become a significant design consideration in the development and construction of long duration earth-orbiting spacecraft.  Even a marble-size piece of space debris can inflict considerable damage to or even destroy an orbiting operational spacecraft or satellite. Considerable resources have been expended by NASA, ESA, and many other countries around the world to design and build spacecraft that can survive in the hostile space environment and which can be protected from damage by pieces of space junk.

In recent years, several companies have announced plans to launch several thousand satellites of their own, mainly for communication purposes, but also to provide a space-based world wide web. Individual satellites provide limited coverage areas – either narrow bands (if in LEO) or small circles (if in GEO) – whereas a satellite system, or constellation, provides a much more extended coverage area. According to plans made public, we can expect upwards of 25,000 new satellites in earth orbit this decade. The question naturally arises, then, regarding what benefits can these large satellite constellations can provide, and what effects they might have on other space activities.

During this presentation, a variety of topics related to space debris will be reviewed, including:

• Where does space debris come from?
• How much space junk is really out there?
• What happens when a spacecraft is hit by a piece of space junk?
• How can we protect a spacecraft against damage by space debris impacts?
• Is there any way to clean up the near earth region of space?
• Will the situation improve or worsen in the future?
• What are some of the possible impacts, both positive and negative, that large satellite constellations might have on space programs and operations?

Presenter

Dr. William P. Schonberg, P.E., D.S.

F.ASCE, F.ASME, AssocF.AIAA

Civil, Architectural, and Environmental Engineering Department

Missouri University of Science and Technology