Space Situational Awareness

RELATED NEWS: SWF Washington Office Director Victoria Samson and Samuel Black of The Stimson Center have co-authored a brief analysis of national security space programs proposed in the FY 2011 defense budget. Download the document here.

Working satellites, debris, space weather and radio frequency interference all affect our ability to use outer space effectively. Knowledge of these parameters is essential for safe and efficient operations in the increasingly crowded orbital regions about Earth. In its most basic sense, space situational awareness is the ability to know not only raw information on what is going on in space but also how it affects our use of space. In other words, space situational awareness, or SSA, helps spacecraft operators understand the constantly changing space environment, counteract perceived threats and adapt to threats, thereby increasing and enhancing the efficient use of space. Image: United States Air Force Integrated Space Command and Control (ISC2), courtesy Lockheed Martin.

The Problem

Humans been accessing space with varying degrees of success since October 4, 1957 and the launch of the first artificial satellite, Sputnik. For more than a half century, people and machines have been launched into space regularly, at rates that range from the peak of over 140 per year during the height of the Cold War to the recent average of 65 to 70 per year.

Unfortunately, each time a launch vehicle boosts a satellite into space, some leftover debris is produced. Fuel tanks are discarded, screws come loose, paint chips flake off and, of course, satellites eventually die. The United States now tracks over 19,000 artificial objects in space bigger than 10 centimeters, about 800 of which are operational satellites. In addition, it is estimated that several hundred thousand untracked objects ranging in size from one to ten centimeters also orbit the Earth, including such things as foil scraps, bolts, and other material. The number of bits and pieces smaller than one centimeter circling our planet may number in the billions. All of this material orbits the Earth at high velocities, usually between seven and ten kilometers per second, and in an uncontrolled manner which can produce considerable injury to human crews and damage to equipment.

Other natural hazards in our planet’s immediate neighborhood include electromagnetic storms from the Sun and gamma rays from outside our solar system.

Radiation from solar flares and coronal mass ejections (CMEs) occasionally send X-rays and high energy particles Earth’s way. This solar activity constitutes the bulk of what is called “space weather,” which may interfere with the operation of space systems, especially those beyond the protective screen of the Van Allen radiation belts surrounding Earth. Knowledge of space weather conditions is important in order to protect spacecraft in orbit and to identify the source of any failures.

Satellites transmit and receive data, and interference with signals can be problematic, even disastrous. The range of frequencies usable by satellites is limited to a few narrow bands because the Earth's atmosphere absorbs a significant portion of the electromagnetic spectrum. The currently available technology and engineering limitations further narrow the range of available frequencies. The end result is that most communication satellites use the very similar frequencies to transmit and receive data as their neighbors. Thus satellite spacing and frequencies need to be carefully regulated. In the geostationary belt where most communication satellites orbit, this regulation is carried out by the International Telecommunication Union. No such regulation exists for other Earth orbits.

In the near future, experts forecast that the number of orbital launches to increase in frequency each year, sending more people and satellites into orbit and, ultimately, to the Moon and other planets. Naturally, satellite operators have been concerned about all of these objects in space, where they are at any given moment, and what function they serve.

Secure World Foundation and space situational awareness

The safety and security of space operations requires that spacecraft operators know and understand the environment around their spacecraft. In the view of the Secure World Foundation, some form of international cooperative SSA effort will be needed in order to manage increasingly congested orbits, especially those in the popular GSO and sun synchronous orbits (SSO), where many of our most important satellites and space missions are located.

Currently, only the United States, with its Space Surveillance Network (SSN) has the technical capability that comes close to what is needed for effective SSA. However, not all of the data are shared publicly because of concerns that they could be used to harm U.S. security interests. Russia and Europe have tracking systems, but these are much less capable than their U.S. counterparts. China, meanwhile, is in the process of developing its SSA capability. Building on previous related work, the Secure World Foundation is participating in international efforts to establish an international SSA system that will make it possible for the community of space faring countries to manage their satellites safely and efficiently.

Clearly, achieving such a cooperative arrangement will depend on an integrated information environment populated by data gathered cooperatively from the international community. Not only do we need technologies that track objects and events in space, we need technologies that do not exacerbate the pollution problem. We also need to share that information with all operators across the globe. Imagine if countries refused to share information necessary to operate aircraft and ships at sea. Operating in these environments would be dangerous indeed.

Be sure to visit the Resources Pages to learn more about SSA in International Space Policy Documents, Reports, Fact Sheets, Links, and Papers and Articles.