In response to a question about the recent ASAT test by India producing a new debris field in LEO, Patrick Murphy, Director of Strategy, Planning, & Integration for NASA Space Technology Mission Directorate asked a question of the NASA director at the Town Hall with NASA Administrator Jim Bridenstine.

In his long answer, Director Bridenstine discussed not only details of what is currently known about the new debris field, but of the much messier 2007 direct ascent antisatellite missile test by China, including the following:

…and still we as a nation are responsible or doing space situation awareness and space traffic management and conjunction analysis for the entire world, and we’re doing it for free compliments of the taxpayer of the United States of America from an orbital debris field that was created by another country.

Why do we do that as a nation? Because it’s the right thing to do, because we want to preserve the space environment, and I know, I know why you asked the question Patrick. At the Space Technology Mission Directorate, you are responsible under Space Policy Directive 3, signed by the president of the United States, for the first time in American history, for building the technologies and the capabilities ultimately to ensure that we can track this kind of debris in the future at a better state than we can right now.

Question: What exactly is Space Policy Directive 3? What does it call for, and is it responsible for establishing the "Space Fence" that Bridenstine mentions almost immediately after this quote? I'd thought that the Space Fence was old news, and has been under construction for roughly a decade already.

  • 1
    $\begingroup$ Did you google "Space Policy Directive 3" and read any of the first 5+ results? $\endgroup$
    – Chris
    Commented Apr 2, 2019 at 14:36
  • 1
    $\begingroup$ @Chris googling is not synonymous with understanding. This is complicated stuff, and understand how these things are connected requires some depth and existing familiarity with both topics. This is what makes Stack Exchange such a great, collaborative environment. When we know things, we post answers, and when we don't, we post questions. $\endgroup$
    – uhoh
    Commented Apr 2, 2019 at 14:42

1 Answer 1


Broadly speaking, SPD-3 establishes new roles and responsibilities for SSA (Space Situational Awareness) and STM (Space Traffic Management).

It shifts the responsibility of managing SSA data (which includes object tracking and collision warning issuance) from the Department of Defense to the Department of Commerce. This shift of responsibility to a civil agency is intended to allow DoD to focus their resources on threats to U.S. space assets and national security, instead of on handling the expected massive increase in commercial satellites from companies like SpaceX and OneWeb in the coming years. DoD will still maintain the authoritative catalog of space objects, but DoC will be in charge of making it more accessible to both public and private interests via an "open architecture data repository".

SPD-3 also calls for NASA, DoT, DoC, and the FCC to collaborate on developing STM best practices, which includes technical guidelines, safety standards, and pre-launch risk assessments. They are tasked with updating the current ODMSP (Orbital Debris Mitigation Standard Practices), which is expected to incorporate standards for new classes of space operations like smallsats and mega-constellations.

Regarding the Space Fence, my guess would be that this directive may affect some of its data sharing agreements. It's been in development for several years now, and is scheduled to come online later this year.


  1. https://www.whitehouse.gov/presidential-actions/space-policy-directive-3-national-space-traffic-management-policy/
  2. https://www.csis.org/analysis/how-does-space-policy-directive-3-affect-space-traffic-management
  3. https://spacepolicyonline.com/news/trump-upstages-spd-3-with-space-force-announcement/
  4. https://www.iadc-online.org/References/Docu/USG_OD_Standard_Practices.pdf

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