COMPASSE members’ comment on ISO/CD3 9490 (Draft Space Traffic Coordination Standard)
Washington, D.C., May 22, 2025
COMPASSE members submitted the following in response to a U.S. Office of Space Commerce call for comments on ISO/CD3 9490, a committee draft of an international standard for space traffic coordination. The draft is under development by ISO Technical Committee 20 (Aircraft and Space Vehicles), Subcommittee 14 (Space Systems and Operations), Working Group 3 (Space Operations).
We are a group of astronomers who have been paying close attention to the increasing number
of objects in Low Earth Orbit. We are very pleased to see a document like this with solid
guidelines for operations in LEO, and we have suggestions for how the document can be
improved. Addressing the escalating congestion in LEO preemptively will help safeguard US
science, security, commercial and safety interests in orbital space.
One overarching recommendation that we make several times is to make as much information
as possible public. Notifications of launches, changes in orbit, and of dangerous situations in
orbit and on the ground, should all be made fully public, not just sent to individual affected
operators or governments.
General comment: the document would be much improved with higher resolution figures.
Figure 3, in particular, is so blurry as to be unreadable.
3.21 We recommend the following change to the definition of space object catalog: “one-to-one
mapping between unique object identifiers, a unique description of what the object is, and a
pointer to ephemeris data for the object.”
6.1 The footnote includes the treaty commitment to the “public and the international scientific
community.” This is best accomplished by ensuring that all of the notifications discussed in
Section 6 (namely 6.2, 6.3, 6.4, and 6.5) are made available publicly, rather than only “to
potentially affected state actors, spacecraft operators, and HAO Service Providers.”
6.3 Includes a note that information should be provided 10 days in advance (if possible) for
upcoming launches that may affect other satellites. We recommend a stronger requirement
here, as launches are always planned more than 10 days in advance. As noted above, we
recommend this information be shared publicly.
6.4 and 6.5 both say “in a timely manner.” We recommend stronger language such as “as soon
as possible” or “as soon as the operator becomes aware of a maneuver/breakup/emergency.”
We also recommend including language here about notifying the general public as well as
government agencies of emergency reentries.
8.1.4 has a small typo. We think it should say: “The STC system approving agent shall set any
additional requirements for the STC system, especially regarding flight safety, security, and
quality control requirements.”
8.2.5: We are very pleased to see this requirement and believe it will make LEO operations
much safer. We would also like to see the document address how it will connect these
requirements to specific launches. This document doesn’t cover licensing, but perhaps it should specify that for each launch notification, a document should be published listing each payload on the launch and the corresponding point of contact.
8.2.6.2: The requirements here such as “to the mm level” are presumably requirements on
precision rather than accuracy, as that level of accuracy would be impossible. This should be
clarified in the text, and a requirement to provide corresponding uncertainty estimates (e.g.,
covariances) should be added.
8.2.6.3 asks operators to provide spacecraft characteristics to minimize collision risk, which we
support. However, the list of characteristics includes maneuver capability with “a simple yes/no,
at a minimum.” In 7.2, operators have already been asked to provide their maneuverability
category as defined in 7.2, and this small bit of extra information on maneuver capability would
be more useful and consistent with the rest of the document.
8.2.6.3. We request a clarification of what is meant by “RF characteristics” here. While we
support any and all sharing of information about spacecraft RF transmissions, please specify
the level of information required that is useful to other space users (including astronomers)
without being overly burdensome to the operator.
8.2.6.5 and 8.2.6.6 instructs operators “to notify within two hours” about a failure in
control functions or a spacecraft breakup event. We feel this language should be stronger to
invoke more urgency. Perhaps “no later than two hours after the event occurs” (this would also
use the same language in Table 2 on P. 24-25).
Thank you for your attention to these points, and for your continued work on space traffic coordination.
Sincerely,
Samantha Lawler, Associate Professor of Astronomy, University of Regina
Jonathan McDowell, Smithsonian Observatory
Michelle Wooten, Assistant Professor of Astronomy Education, University of Alabama at
Birmingham
Aparna Venkatesan, Professor of Physics and Astronomy, University of San Francisco
Teznie Pugh, professional astronomer
Diane Turnshek, Special Faculty, Physics Department, Carnegie Mellon University
Connie Walker, professional astronomer, independent citizen
Meredith Rawls, Research Scientist, Astronomy Department, University of Washington