Approximately 19,000 manmade objects larger than 4 inches in diameter are currently in low-Earth orbits, threatening to collide with satellites and spacecraft.

Some are defunct spacecraft while others range from a tool bag and lense caps that got away from astronauts to debris from colliding satellites.

They endanger the crews on both the Space Shuttle and International Space Station.

Those attending the International Conference on Orbital Debris Removal heard dozens of ideas on how to clean up this mess, which won’t be cheap or easy.

Schemes range from using huge aerogel-laden puff balls to capture debris to various types of nets and tethers.

One of the more promising ideas came from NASA. The agency proposes the use of rapid-fire laser pulses to vaporize a small portion of the junk. That would provide enough drag to reduce the object’s speed and allow it to re-enter the atmosphere, where it would burn up.

Beyond the huge price tag, one of the biggest obstacles to obtaining an international treaty for the task is that any system could also be considered a space weapon since it could be used to attack operational satellites.

Another problem is that the objects still belong to someone or some nation on Earth. An international treaty to collectively allow their removal from space would be needed.

Photo: European Space Agency