Starlink satellites visible in a mosaic of an astronomical image.
Courtesy of NSF’s
National Optical-Infrared Astronomy Research Laboratory/NSF/AURA/CTIO/DELVE)

An international open Letter on kinetic anti-satellite (ASAT) testing has been sent to the United Nations General Assembly, urging that body to take up a treaty that would prohibit debris-generating anti-satellite weapon tests.

Coordinated by the Outer Space Institute (OSI) in Canada, the letter underscores the need for such a treaty, driven by the rapid escalation of satellites in orbit.

UN General Assembly.
Credit: UN


OSI, based at the University of British Columbia, is a transdisciplinary network of global space experts that addresses challenges facing the continued use and exploration of space.

Credit: OneWeb



“The number of active and defunct satellites in orbit has grown from 3300 to over 7600 in the last decade,” the letter explains, “with the potential addition of as many as 100,000 active satellites within the next ten years.”

Spotlighting the near-future orbital environment, the letter points to at least four planned ‘mega-constellations’ from different countries:

  • SpaceX’s Starlink (U.S.) with 42,000 satellites
  • Amazon’s Kuiper (U.S.) with 3,236 satellites
  • OneWeb (United Kingdom) with 7,000 satellites
  • Guo Wang’s (China) StarNet with 12,992 satellites

“This rapid growth is raising concerns about collisions and the proliferation of space debris, endangering all forms of space use, from crewed missions, to communications, to Earth observations and environmental monitoring, to space-based astronomy,” the OSI open letter adds.

Consequences of a low-altitude kinetic ASAT test in a mega-constellation environment.
Credit: OSI – Data from USSPACECOM and FCC/ITU Filings

Wanted: major step

New practices are needed for the safe and sustainable use of space. To this end, a major step would be a kinetic ASAT test ban treaty, the letter explains. “Kinetic ASAT weapons, whether ground-based or space-based, employ high velocity physical strikes through the use of a ‘kill vehicle’ or shrapnel to destroy or disable objects in orbit.”

Due to the high impact energies involved, fragments from a kinetic ASAT test often ends up on highly eccentric orbits that cross multiple satellite “orbital shells” twice per revolution.

“If just one piece of debris from such a test collides with a satellite and causes a major fragmentation event,” the letter continues, “this could lead to additional events affecting all States, which could include further fragmentations, satellite failures, or service disruptions.”

Early signatories

As proposed, a kinetic ASAT test ban treaty would prohibit the use of any high velocity physical strikes during testing. “Fly by” tests would still be permitted, the letter adds.

For these reasons, the letter includes signatures from a who’s who of space authorities urging the United Nations General Assembly to take up consideration of a kinetic ASAT test ban treaty.

An appended list of early signatories is led by Michael Byers, Canada Research Chair in Global Politics and International Law, University of British Columbia and co-director of the Outer Space Institute.

To access the “International Open Letter on Kinetic Anti-Satellite (ASAT) Testing,” go to:

Should you wish to add your name to the list, go to:

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