In the first group of questions below the block quotes, I've illustrated situations where a large number of cubesats are deployed at one launch (56 an 104 satellites) and it seemed to take quite a while for it to be figured out which one was which.

That can be a problem considering both the number and that fact that many of the cubesats launched in groups like this are experimental, and may not work, and so may end up almost indistinguishable. (see T.S. Kelso's "Space debris on release" below)

Question: Considering that

  1. Constellations of thousands to ten-thousand satellites are being considered
  2. Cubesats are probably just going to get more and more popular in the future
  3. Some rockets are getting much bigger, many are getting much cheaper
  4. Tracking technology isn't likely to grow or expand as quickly as the cubesat deploy and identification loading

What are proposed and recommended thing that can be done during deployment that would make it easier to get quick and reliable identifications in these situations? T.S. Kelso's comment about attitude information seems important, but I am not sure what the point is there exactly. CSpOC seems to have some recommendations, but I am not sure how they would be implemented by the various launch vehicles and agencies (SpaceX, ISRO, Rocket Labs) that are or will soon be doing many-cubesat deploys.

Space.com's Cluttering the Space Commons? Upcoming SpaceX Launch Irks Orbital Debris Experts quotes T.S. Kelso (Celetrak-guy):

Space debris on release

"What they [Spaceflight] haven't shared is how these 70+ satellites are going to be deployed," said T.S. Kelso of CelesTrak, an analytical group that keeps an eye on Earth-orbiting objects. (Note: A Spaceflight press release from August stated that 71 satellites would be aboard the launch, but the company's website currently says the number is "64+.")

"I checked with one of the operators — trying to get a head start on how we're going to ID all of these —and learned that the two SHERPA platforms are going to be released from the Falcon 9 with no attitude control or attitude determination."

Kelso's bottom line: "I think this is not only irresponsible from a safety-of-flight perspective, but it jeopardizes the time and resources of many of the small operators who may never even hear from their satellites," he told Inside Outer Space.

Kelso's guess is that about one-third of the satellites to be deployed will basically be space debris on release and there will be difficulties in sorting out this kind of mess.

Be prepared for chaos

Kelso spoke extensively with the U.S. Air Force's 18th Space Control Squadron team last week, at the Space Situational Awareness Operators' Workshop in Denver. The 18th Space Control Squadron, which is based at Vandenberg, detects, tracks, and identifies all artificial objects in Earth orbit.

"They have next to nothing useful from Spaceflight for the SSO-A launch on Monday. This is totally irresponsible. Be prepared for chaos," Kelso tweeted on Friday (Nov. 16).

I reached out to Spaceflight for comment for my previous article about this launch, "Cluttering Space: Upcoming Launch Red Flagged." In response to that query, Spaceflight spokeswoman Christine Melby said via email: "Thank you for reaching out. At this time we do not have a comment on this article."

There seems to be concern from other sectors as well:

But some other experts remained concerned.

"CSpOC [the Combined Space Operations Center] has developed a set of recommendations for optimal cubesat operations, including launch deployment and identifications," said Jer-Chyi Liou, NASA's chief scientist for orbital debris in the Orbital Debris Program Office at the agency's Johnson Space Center in Houston.

"It appears that the recommendations were not taken seriously by the SSO-A developers," Liou told Inside Outer Space.

Those recommendations were based on the proliferation of cubesats and associated technology that pose unique tracking and identification challenges. You can read the recommendations here.

Problems Assigning IDs for multi-satellite deployments:

Other Problems keeping track of satellites:


Artist's illustration of the payloads launched during the upcoming SSO-A mission separating from their SpaceX Falcon 9 rocket. Credit: Spaceflight Source

  • $\begingroup$ Good question, although some may consider this question opinion-based. I would prefer this question be left open and answered. $\endgroup$
    – DrSheldon
    Nov 21, 2018 at 16:28
  • $\begingroup$ @DrSheldon considering that I've offered leads to two very fact-based options, and it's all based on existing science and technology, there is plenty of room for fact-based answers. There is really no such thing as "opinion-based questions" by the way, only questions that can only have opinion-based answers. $\endgroup$
    – uhoh
    Nov 21, 2018 at 16:46
  • 1
    $\begingroup$ "Satellites should have some maneuver capability to facilitate conjunction avoidance on-orbit. Satellites should be built to allow controlled reentry or expedited uncontrolled reentry to minimize the threat of individual CubeSats beyond the satellite’s mission life." This could become mandatory devices built in cubsat frames sold at cubesatshop. $\endgroup$
    – user19132
    Jan 29, 2019 at 11:26
  • 2
    $\begingroup$ @uhoh it's in the "you can read recommendations here" link $\endgroup$
    – user19132
    Jan 29, 2019 at 11:31
  • 1
    $\begingroup$ @uhoh I focused too much on the space debris chain reaction threat. Still there should be one mandatory device in each cubesat frame, containing one safe tracking module and one safe deorbit (thruster+attitude control) module, ideally taking less than 100% of 1U volume. $\endgroup$
    – user19132
    Jan 29, 2019 at 14:29

1 Answer 1


The key consideration in Kelso's comments is that many of these satellites end up DoA, so you cannot rely on the satellite helping you in any way. Thus we are left with the need for passive methods to identify these dead satellites. The generally proposed concept is to have something on the satellite that makes it brighter to RADAR, such as reflectors

This question talks at length about a mission that proposes using such reflectors.

Search Google for "Space Traffic Management" and you will get lots and lots of papers with many other proposals. I co-authored one such paper three years ago; Space Traffic Safety: A New Self-Governance Approach for the Smallsat Community SSC17-XI-02. The subject is really too complicated for a Stack Exchange answer, but here is a bit from that paper:

A number of potential technical solutions exist to help improve the tracking accuracy for small satellites. For instance, in 2006 a set of post-launch guidelines were suggested by members of the Space Analysis branch of the Air Force Space Command that would significantly improve the tracking ease during the initial object identification period. These included:

  1. Coordinate launch trajectory and initial orbit information.
  2. For multi-satellite launches information regarding deployment sequence, separation timing, and object shape and size is extremely beneficial.
  3. Sequential satellite deployments should be separated by at least 20 seconds.
  4. Separation velocity between the satellite and the launch vehicle should be at least 5 meters/second or more.
  5. Report problems identified in two-line element sets.
  6. Notify tracking authorities if assistance is desired with issues regarding satellite anomalies and/or loss of contact.10

10DeVere, G. and J. C. Randolph. “How to Improve Small Satellite Missions in Two Easy Steps: Adopting Space Debris Mitigation Guidelines and Improving Space Surveillance Network Tracking Support”. Proceedings of the 20th Annual AIAA/USU Conference on Small Satellites, 2006.


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