Analysis of the Cosmos 1408 Breakup

At the time of this writing, it’s been three days since the breakup of the Cosmos 1408 satellite. The debris created from the fragmentation of Cosmos 1408 has not been fully cataloged or characterized yet, and will likely not be for some time. However, from early measurements and a knowledge of previous relevant breakup events, several observations can be made. It should be noted that much of the information required to re-create accurate simulations of this event will likely never be available, so the community will have to rely on empirical observations of the fragments and “rules of thumb” developed analyzing past similar events. One thing is for certain:

There will be some potential collision risk to most satellites in LEO from the fragmentation of Cosmos 1408 over the next few years to decades.

The first question we’re all wondering is…how many new pieces of space debris resulted from this new event, and where are they? We can start by examining the extent of previous highly energetic collision events in LEO, namely the Iridium 33 / Cosmos 2251 collision of 2009 and Chinese ASAT destruction of Fengyun 1C in 2007. Then we can compare this to early information gathered on newly detected objects to glean some insights.

Cosmos 1408 — Before the ASAT Test

First, some observations about Cosmos 1408 and its orbit. While any ASAT test is a terrible idea, this one occurred in one of the worst possible orbits. This satellite was in a high inclination orbit, at an altitude that put it right in the middle of many other operational assets; notably, it was less than 100km above the International Space Station, and less than 100km below multiple commercial constellations including SpaceX’s Starlink fleet.

Orbit path of Cosmos 1408 satellite prior to breakup

Cosmos 1408 was also a very large satellite, with a reported mass of ~2,200 kg. LeoLabs reported radar cross-section (RCS) was 8.63 meters squared.

LeoLabs high level information on Cosmos 1408

The Day of the ASAT Test

As LeoLabs is first and foremost a space safety company, this breakup was an “all hands on deck” event for us. Upon first hearing the reports of a possible ASAT test on the morning of November 15, we immediately began checking our data on Cosmos 1408. We saw that we had been regularly tracking this satellite roughly three times per day without issue.

LeoLabs tracking data on Cosmos 1408 for 30 days prior to the breakup event

Over the past 30 days prior to the ASAT impact, we had collected 1,796 radar measurements and generated 69 state vectors with position uncertainties regularly under 100 meters. In short — the Cosmos 1408 satellite was well tracked by our system prior to this event.

As we checked our tracking data for Cosmos 1408 on the morning the ASAT test was reported to have occurred, we noted that our last few planned tracking passes did not return expected data. This was a troubling sign that indicated something was off-nominal, but we needed additional information to confirm. So we tasked Cosmos 1408 to the highest level of prioritization on our space radar network, and scheduled extended observation windows on the next pass to collect additional information.

The next pass occurred at 16:20 UTC, at our Kiwi Space Radar in New Zealand. Our Data Science team was standing by as the data rolled in, and upon review, we quickly noted a “multiple headcount” scenario; that is, we detected multiple individual objects where we would nominally only expect one object. This was a clear confirmation from us that a breakup had occurred, sadly supporting the reports of the successful ASAT test.

Subsequent radar passes over the next two days increased the number of detected fragments significantly. As of this writing, we’ve detected nearly 300 unique fragments and continue to analyze the data.

LeoLabs data collected on new Cosmos 1408 debris taken from Costa Rica Space Radar

Within a day of the Russian ASAT test, the 18th Space Control Squadron notified the general public that they had initially detected around 1500 possible associated objects from this impact.

Initial Data Assessment

An initial look at the orbits of some of the new fragments is shown in the Gabbard diagram below. A Gabbard diagram plots the apogee and perigee of breakup fragments against each of the fragments’ orbital period. They are a convenient way to get a quick visual representation of the “landscape” of space fragmentation events, and have been used for decades in the space industry to analyze such events.

Here, blue dots denote the apogee while the “partner” orange dots denote perigee for the same object. The apogee / perigee points for one sample object have been circled in red for ease of interpretation.

Gabbard diagram of LeoLabs data on 253 new Cosmos 1408 debris objects

This Gabbard diagram shows 253 objects whose orbits have already been preliminarily characterized by LeoLabs (as of 17 November 2021). These data are being refined as our global network of radars provide more detail of the new objects.

Our initial assessment is that these 253 objects likely represent the largest fragments with the least amount of delta velocity imparted to them, as they are orbiting closest to the original orbit of Cosmos 1408. If this is accurate, rules of thumb would indicate 5–10x more objects than this, putting total notional trackable debris counts in the area of 1,250–2,500 pieces.

Given the precarious altitude where this event occurred, the Gabbard diagram provides us with two key takeaways for this event:

1. Objects ejected into lower perigees will have their orbits circularize relatively quickly, and the majority will re-enter the atmosphere over the next five years.
2. Objects ejected into higher orbits will have their orbits circularize more slowly, and the majority will re-enter the atmosphere over much longer timeframes — potentially decades, depending on altitude.

The collision risk from this resulting debris in the short-term is largely dependent on the orientation of an object’s orbit and the expanding cloud of debris. However, within weeks to months of the breakup, the debris will largely be dispersed around the Earth (i.e., global spread of the fragments’ right ascension of the ascending node). Thus, ultimately the statistical collision risk to other LEO satellites will then be predominantly dependent on altitude.

New Spatial Density of Space Debris

While the Gabbard diagram does a good job of showing the range of altitudes generally affected by this event, the spatial density of resident space objects (RSOs) provides a better way to depict and quantify the statistical collision risk. Statistical collision risk is proportional to the spatial density of the RSO population at that altitude.

The plot below shows our best estimate at the new, current debris distribution. The black spatial density curve provides the number of RSOs per volume as a function of altitude before the breakup of Cosmos 1408. The red line depicts the likely new spatial density values immediately after the breakup event due only to these new fragments.