Declaration:
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.
Background:
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 : space-track.org) –
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 https://comspoc.com/neat/) 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.
Summary
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.
Answer:
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?
Answer:
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?
Answer:
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.