Decades of space activity have littered low Earth orbit with debris, and as the world's spacefaring nations increase their activities, the chance for collision increases. The security of space also is threatened by what U.S. State Department Deputy Assistant Secretary for Space and Defense Policy Frank Rose Sunday called "irresponsible actors."

Computer generated image of objects in Earth orbit that are being tracked. About 95 percent of them are debris, not functional satellites. [NASA]?

"Irresponsible acts against space systems have implications beyond the space environment, disrupting services upon which civil, commercial, and national security sectors around the world depend, with potentially damaging consequences for all of us and to future generations," warned Rose.

For these reasons, the U.S. government has decided to join with the European Union and other nations to develop an International Code of Conduct for Outer Space Activities, Rose told colleagues at the 7th Ilan Ramon International Space Conference at Herzliya.

The conference is held annually in memory of Ramon, the first Israeli astronaut. He served as space shuttle payload specialist of STS-107, the fatal mission of Columbia, in which he and six other crew members were killed in a February 2003 re-entry accident.

A Code of Conduct "will help maintain the long-term sustainability, safety, stability, and security of space by establishing guidelines for the responsible use of space," Rose told the conference attendees.

Rose was conveying to the conference the policy set forth on January 17 by U.S. Secretary of State Hillary Clinton, who said, "The long-term sustainability of our space environment is at serious risk from space debris and irresponsible actors. Unless the international community addresses these challenges, the environment around our planet will become increasingly hazardous to human spaceflight and satellite systems, which would create damaging consequences for all of us."

"Ensuring the stability, safety, and security of our space systems is of vital interest to the United States and the global community. These systems allow the free flow of information across platforms that open up our global markets, enhance weather forecasting and environmental monitoring, and enable global navigation and transportation," Clinton said.

Today there are approximately 60 nations and government consortia that operate satellites, as well as numerous commercial and academic satellite operators, creating an environment that is increasingly congested.

The U.S. Department of Defense tracks roughly 22,000 objects in orbit, of which 1,100 are active satellites.

In addition, there are hundreds of thousands of additional objects too small to track but still capable of damaging satellites in orbit and the International Space Station.

"We need to work with the international community to address hazards and concerns that have arisen from this increasingly congested space environment," said Clinton.

The United States will work with the European Union's draft Code of Conduct for Outer Space Activities, published by the EU in 2008 with a revised draft released in September 2010.

Among its concerns, the EU draft takes into account "that space debris constitutes a threat to outer space activities and potentially limits the effective deployment and exploitation of associated space capabilities" and strives for "the formation of a set of best practices aimed at ensuring security in outer space could become a useful complement to international space law."

At the space conference, Rose drew a more detailed picture of how a Code of Conduct might work.

"Ensuring the long-term sustainability, stability, safety, and security of the space environment - through measures such as providing prior notifications of launches of space launch vehicles, establishing "best practices guidelines," and warning of risks of collisions between space objects," Rose said, "are in the vital interest of the United States and the entire world community and enhance our mutual security interests."

One of the ways the United States is moving forward in 2012 is through pursuit of "near-term, voluntary, and pragmatic transparency and confidence-building measures," which Rose called "TCBMs."

"Through TCBMs we can address important areas such as orbital debris, space situational awareness, and collision avoidance," said Rose, "as well as undertake activities that will help to increase familiarity and trust and encourage openness among space actors."