Our imaginations are on fire and our gazes once more turned upwards.


With a renewed interest in Mars and pioneers such as Jeff Bezos and Elon Musk ushering in an era of private spaceflight, there have never been more possibilities for leaving our atmosphere. The flipside is that since the inception of space flight, humans have left our technological litter in orbit.


Now the question is: When does space debris come back to earth, does it pose a danger and how can we clean it up? Dr Pieter Kotzé of the Centre for Space Research has the answers.


Firstly, what is space debris?

Space debris consists of objects in low-Earth orbit (at an altitude of 300 km to 500 km). These debris objects can be as large as defunct satellites and spent rocket parts all the way down to nuts, bolts and flecks of paint.


Orbital debris is any human-made object in orbit about the Earth that no longer serves a useful function. Such debris includes non-functional spacecraft, abandoned launch vehicle stages, mission-related debris and fragmentation debris.


Since the launch of Sputnik, how would you describe the increase in space debris?

From zero in 1960 to more than a million pieces of junk in 2021.


How much of it is out there?

There were estimated to be over 128 million pieces of debris smaller than 1 cm as of January 2019. There are approximately 900 000 pieces from one to 10 cm. The current count of large debris (defined as 10 cm across or larger) is 34 000.


How much of a danger does space debris pose for the launch of satellites and future space flight?

This is always a risk that satellites with astronauts on board, such as Space X, could be hit by a piece of space debris.


Collisions with debris larger than 1 cm would disable an operational spacecraft, and may cause the explosion of a decommissioned spacecraft or rocket body. Impacts by millimetre-sized debris may cause local damage or disable a subsystem of an operational spacecraft.


Who should take responsibility for cleaning up space debris and what plans are in place to do so?

Space junk is no one country's responsibility but the responsibility of every spacefaring nation. The problem of managing space debris is both an international challenge and an opportunity to preserve the space environment for future space exploration missions.


Should we on the ground be worried about space debris returning home with a bang?

Although most debris burns up in the atmosphere, larger debris objects can reach the ground intact. According to NASA, an average of one catalogued piece of debris has fallen back to Earth each day for the past 50 years. Despite the size of some pieces of debris, no significant property damage has occurred.


Has anybody been hit by space debris?

Only one person has ever been hit by space debris. Her name is Lottie Williams*.


Who is responsible for space debris?

There is no one responsible for tracking it internationally, but the United States does track space debris to protect its own satellites, and it shares some of that information with the rest of the world.


Other nations also have tracking capabilities and perform similar services for their satellites.


What methods can be used to remove space junk in orbit?

The development of clean-up technologies has been under way for years. In 2016, Japan's space agency sent a 700-metre tether into space to try to slow down and redirect space junk. In 2018, a device called RemoveDebris successfully cast a net around a dummy satellite.


Technological fixes include removing space debris from orbit with nets, harpoons or lasers.


34 000


128 mil.


900 000


Debris fallen as of January 2019:

Debris fallen to earth:


* According to various internet sources, Lottie Williams was exercising in a park in Tulsa, Oklahoma, on 22 January 1997 when she was hit in the shoulder by a small piece of falling space debris. It was from the Delta II rocket (used for the April 1996 launch of the Midcourse Space Experiment) that had crashed into the atmosphere. The object tapped her on the shoulder and fell off harmlessly onto the ground.

One catalogued piece of debris has fallen back to Earth each day for the past 50 years.


What is out there?

“Only one person* has ever been hit by space debris,” says Dr Pieter Kotzé of the Centre for Space Research.