Ruminations and Analysis on a Russian ASAT
11/25/2021 | Jim Cooper, Dan Oltrogge, Sal Alfano | News


In reflecting on Russia’s Anti-Satellite (ASAT) test on Monday, COMSPOC, along with like-minded government and commercial entities worldwide, emphatically denounces Russia’s ASAT test, conducted on November 15, 2021.  Russia’s actions stand out as the epitome of irresponsible behavior in the face of the cooperative, concerted efforts of other space-faring nations and commercial entities to maintain the long-term sustainability of space for the benefit of all humankind.



On November 15, 2021, Russia conducted an ASAT test, launching a Nudol ASAT weapon system from Plesetsk Cosmodrome to intercept and destroy the on-orbit COMOS 1408, a defunct Soviet Electronic Intelligence (ELINT) satellite that was launched in 1982.  The resulting orbital debris field will degrade and complicate the space operational environment for years to come, needlessly increasing the risk of operating spacecraft, including manned platforms such as the International Space Station (ISS).


The intentional causation or release of orbital debris is contrary to the following guidelines and standards adopted by many space-faring nations, including Russia:

(NOTE: COMSPOC Corporation is leveraging open-source information for this analysis and will continue to update as more information becomes available.)


Description of the event:

Date – November 15, 2021

Impact time – 0246-0248 UTC

Weapon – S-550 “Nudol” ASAT missile (source: Russia Teases New S-550 Missile System - The Moscow Times)

Launch site – Plesetsk Cosmodrome, Russia

Target – Cosmos 1402

  • Dead Soviet ELINT satellite
  • Mass 2108 kg (source: DISCOS database)
  • Launched in 1982

Orbit of target (in Two-line element set (TLE)) format (source : – 

1 13552U 82092A   21319.03826954  .00002024  00000-0  69413-4 0  9995

2 13552  82.5637 123.6906 0018570 108.1104 252.2161 15.29390138142807


Assumed engagement conditions

The Russian “Notice to Airmen” (NOTAM) and maritime notices (NOTMAR) messages, published from 0200-0500, were indicators of the sequence of events.   We assumed that the NOTAM2 area (in yellow, with a corresponding maritime area) corresponds to a reentry corridor for the first stage, while the NOTAM3 area (in purple) corresponds to a reentry corridor for fragments stemming from the S-550 ASAT weapon itself.


Our interceptor trajectory, then, was designed to launch from Plesetsk with a ballistic reentry in the NOTAM3 area. This resulted in a relative velocity between the ASAT and COSMOS 1408 in our representative engagement of approximately 4 km/s. These collision conditions likely do not qualify as a catastrophic or "complete disintegration" collision; collisions are typically thought of as catastrophic when the energy to mass ratio exceeds an approximate threshold of 40 kJ/kg, below which deformation is more prevalent and fragmentation therefore less. But the extent of fragmentation is also material-dependent, and the transition from catastrophic to non-catastrophic is likely gradual.


In any case, this collision may have less than the 3,000 trackable fragments estimated by our model (an adaptation of NASA’s Standard Breakup Model that additionally adheres to first principles and physics conservation laws). However, the announcement by the U.S. of tracking 1500 fragments during the first day alone (and anticipated detection and orbit custody of many more over the coming months) serves as a lower bound on the number of fragments created.


ASAT engagement simulation

The pictures below provide a representative depiction of the Russian ASAT intercept of the defunct COSMOS 1408 spacecraft. A brief YouTube animation is provided: 

COMSPOC engagement and fragmentation depiction of 15 Nov 2021 Russian ASAT intercept of COSMOS 140



While elements of the engagement (timing, staging, interceptor mass, etc.) remain unclear, the overall fragmentation, debris cloud evolution, and severity of the event depicted by this simulation are likely to be quite representative of the actual event. Note that many orbital regimes are affected by this event. 





Encounter rate increases

COMSPOC’s Number of Encounters Assessment Tool (NEAT, freely available at is a quick way to estimate, for a given spacecraft or constellation, how often an operator’s spacecraft may need to conduct collision avoidance maneuvers (and if not effectively done, how often they can expect their spacecraft to collide with another space object). Unfortunately, such characterizations become out of date when the space catalog materially changes (as occurred with this Russian ASAT event). 




But how much did encounter rates change?  The plot below shows our estimate of how spacecraft operators (including human space stations) will now have to increasingly maneuver to avoid high collision risk events.  The color bar areas shaded in gray represent the additional collision risk introduced by this ASAT test; significant increases can be seen at and above operational altitudes for the International Space Station (ISS) at 420 km, earth observing spacecraft altitudes (~440 km), and Starlink deployment, orbit raising, and operational altitudes (350 to 550 km).




Fragmentation debris orbit characterization

It is important to understand what orbits the new COSMOS 1408 debris fragments will occupy. The Gabbard plot (below) shows the distribution of orbit altitudes that those fragments may occupy. Note that many orbital regimes will be adversely affected by this event as shown.  Further still, as the orbits of these fragments decay, critical spacecraft such as the ISS (green dotted line in the figure) and many commercial and civil communications and earth observing spacecraft will be placed at even greater risk.



Orbit lifetime of debris fragments

One of our breakup simulation’s products is the estimated lifetime of each of the 14,871 fragments it models. The figure below indicates the distribution of estimated lifetimes (time to reenter earth’s atmosphere).  Note that this is a logarithmic scale to better present the data on a single chart. While perhaps 6,500 of the debris fragments may reenter during the first year, thousands of fragments will have multi-year lifetimes, with some of those exceeding twenty years.






We have developed a representative scenario for this ASAT test.

This irresponsible test generated a significant fragmentation debris field, which will require more SSA information and understanding, strain limited flight dynamics and management resources, and cause the expenditure of finite maneuvering fuel.  The potential introduction of 3,000 trackable and 12,000 lethal non-trackable (LNT) debris fragments will cause even more conjunctions and collision risk than presently estimated.



Questions and Answers:

Question: In the YouTube video, I understand the weapon was in front of the target, with a typical velocity at the impact time of some 4 km/s, leading to a relative velocity of 4 km/s. But then how comes that in the Gabbard we see most debris “gaining” velocity instead of “losing” it? The increases in apogee altitude seem counterintuitive for an impact in a direction that opposes the target’s velocity.


Your question about the Gabbard Plot is a good one.  While hard to see from the video, the ASAT approaches (in our assumed scenario) from the left (slightly) and 1408 approaches it (as you mention).  My response is that in such a collision, much kinetic energy is expended (released), and the direction of that release is fairly uniform in all directions.  The key in modeling it is to ensure that linear momentum is conserved.  I recall a trip to a rifle range for one of my son's school science projects on the topic of kinetic energy where we conducted live fire tests to determine how fragments of a grapefruit are dispersed when impacted by a high-speed projectile.  Though similarly counterintuitive, we found that grapefruit fragments were equally dispersed in all directions (i.e., not favoring the projectile's original direction of motion).

Question: From your diagram “composition of annual collision risk by RSO type”, I understand the collision risk with debris is increased by some 8% for Starlink, and kind of doubles for the ISS (but still low). Do I understand correctly?


Yes, this interpretation is correct.  However, this is a dynamic situation, so as the orbits of the fragments decay, they will pose a greater risk to the ISS as they lower through the ISS orbit altitude.

Question: Do you consider that you already have all the potentially trackable debris from the collision, or can this increase in the coming days?


Keep in mind that our representative results are based on simulation, and there will be much searching for more debris for weeks and months and years before the actual extent of the debris field is known.