@shell_jim
Account based inUnited States
About this account
- Account based in
- United States
- Connected via
- United States App Store
Account-level information from X, not a live location or the device used for a specific post.
Space surveillance, SSA/SDA, orbital debris expert. Retired USAF with 30+ years of space experience. Physics (M.S.) and Imaging Science (PhD). USAFA '92.
Joined February 2012
- Tweets1.8K
- Following271
- Followers2.3K
- Likes7.1K
Pinned Tweet
3/n This animated plot illustrates the evolution of the orbit plane of the debris field, with the color coded to the area/mass of the objects. Only objects with an accuracy < 1000 km at epoch are shown (677 as of 2025-02-24).
China's active Yaogan-50 02 satellite experiences a debris event on around 20 July 2026, but appears to still be maneuver capable. 43 pieces of debris cataloged to date. Although high altitude, the debris appear to have a high area to mass and thus much shorter lifetimes than originally anticipated. Details in my substack post (link in thread)
Substack post with more details here -> spacedomain.substack.com/p/c…
💥 🛰️ Debris event from USSF's "LDPE-1" GEO Satellite on 27 July 2026.
The Long Duration Propulsive ESPA-1 (LDPE-1) appears to have experienced a debris event on 27 July 2026 at 12:50 UTC (+/- 30 min). This is satellite 49818 in the @SpaceTrackOrg catalog (Int Des 2021-118B).
Two public sources of data corroborate the event:
1️⃣ orbital position information from @S4S_SDA via space-track.org (see graphic below) and
2️⃣ seven new objects appeared in the Vimpel catalog which associate back to LDPE-1 at a time concurrent with the orbit change--to within a ~ 1 hr window 2 sigma'ish
Thankfully LDPE-1 was operating in a supersynchronous orbit ~365 km above GEO altitude, or clear of the GEO Protected Region at the time of the event, and fully remains clear of the GEO Protected Region. The last noted meaningful maneuver was in April 2026, but predominant sources indicate the satellite was still active.
Unfortunately, some of the debris generated now encroaches into the GEO Protected Region.
LDPE-1 is a Northrop Grumman "ESPAStar" payload. There are several ESPAStar payloads active in GEO today with more missions planned. Hopefully the systemic root cause of the debris event is not something that could be repeated in the other platforms.
#SpaceDebris #LongTermSustainmentOfSpace #SpaceDomainAwareness #SpaceDomainNormsOfBehavior
Orbit data from @S4S_SDA via space-track.org, used with permission per ODR 24-002-4.
Debris associated with Russian upper stage from Feb 2026 GEO launch cataloged.
On 12 Feb 2026, a Russian GEO launch placed Elektro-L No.5 (67756 / 2026-028A) and the first Iranian GEO satellite, "Jam-e Jam 1" (67757 / 2026-028B).
@mickeywzx caught the GEO insertion and subsequent Block DM-03 rocket body (67758 / 2026-028C) passivation with an amazing EO collect video, cropped portion below. (Original video here nitter.cf/mickeywzx/status/20232…)
The passivation appeared to result in numerous additional objects. It was unclear at the time if this was simply ice (frozen liquid oxygen effluent) from the depletion burn, or if persistent objects may actually be present.
In the video, Elektro-L No.5 and the Jam-e Jam 1 satellite are seen receding to the upper left relative to the upper stage (presumably the brighter object is Elektro-L No.5).
Well, it appears there were in fact some persistent objects. A piece of debris (100099 / 2026-028D) from the upper stage was cataloged by U.S. Space Forces – Space (S4S) on 20 July 2026. It is likely additional pieces accompanied this one, but they may not be held in track custody with sufficient fidelity to enter the catalog.
#SpaceDomainAwareness #SpaceDebris #LongTermSustainment
SUMMARY: US cataloged new debris object. Object determined to originate from PRC's operational geosynchronous satellite Gaofen 13 in early 2024. Russia has been tracking the debris object since close to the origination time. No apparent anomalies with Gaofen 13 - observables support continued routine operations. Debris object is relatively dim and has a high area/mass.
DETAILS:
Today @S4S_SDA cataloged a new piece of debris in geosynchronous orbit attributed to an object with international launch designator 2020-071. This was the launch of China's Gaofen 13 satellite (46610 / 2020-071A) - widely understood to be a GEO-based large aperture optical system providing persistent surveillance of the PACOM area of responsibility (AOR).
I determined the newly US-cataloged debris object (62337 / 2020-071C) has been in custody by Russia since near the time it originated from GAOFEN 13 (Vimpel catalog object 143589). Examining the historical Russian states, it's probable the object originated from GAOFEN 13 around 10-14 Jan 2024.
GAOFEN 13 is clearly still operational and is routinely performing both N-S and E-W (longitudinal) station-keeping maneuvers at 118 deg E (ref graphic).
OBJECT PROPERTIES
1️⃣ Optical Signature: The object is relatively dim having a normalized visual magnitude of ~16.6 Mv, or equivalent to an approximately 0.5 m diameter sphere (assuming a 0.2 albedo).
2️⃣ Area to Mass: The object has a very high area to mass of ~ 2.8 m^2/kg, thus subject to significant solar radiation pressure perturbations. These perturbations produce an annual eccentricity cycle which will oscillate from 0 to ~0.09 (it is near a peak now).
3️⃣ Mass: this is a crude estimate, but given the optical signature and area / mass, I estimate the object to be ~0.01 kg (10 grams).
This appears to be a low-energy "shedding" event with likely few additional objects. The debris object will be challenging to maintain due to the high solar radiation pressure and dim optical signature.
#SpaceDebris #SpaceDomainAwareness
Orbit data from @S4S_SDA via @SpaceTrackOrg, used with permission per ODR 24-002-4.
H/T @planet4589
NASA's "Orbital Debris Quarterly News" released today.
My personal highlight in this issue: the HUSIR and Goldstone radar measurements of small debris in Low Earth Orbit (LEO). These measurements are of the uncatalogued debris population too small to be reliably tracked and maintained.
A surprise: a new population of debris objects since mid-2024 at an inclination of approximately 88 degrees and at an altitude < 500 km, but without an identified source or discrete event. Hmmm......
Check it out here --> orbitaldebris.jsc.nasa.gov/q…
New space debris originating from China's Yaogan 25C satellite
On 30 June 2026, @S4S_SDA cataloged three new pieces of space debris identified as originating from China's Yaogan 25C satellite (40340 / 2014-080C).
🚨 Most sources indicate Yaogan 25C is still an active satellite.
I have determined with relatively high confidence the debris originated from an event during a 10 hour time period on 28-29 Sep 2025 (UTC).
Graphic below shows all three Yaogan 25 satellites which are part of this launch group. A small semi-major axis (height) perturbation appears to correspond to the debris origination time, as precession of the current debris orbital planes back to that date are highly aligned.
More to come (I hope I get some time to provide further analysis, so include photometric signature behavior).
#SpaceDebris #SpaceDomainAwareness
Orbit data from U.S. Space Forces – Space (S4S) via space-track.org, used with permission per ODR 24-002-4.
🛰️ Satellite megaconstellation optical brightness compared to @IAU_CPS maximum recommendations
So how are things looking for the international Dark and Quiet Skies initiatives to preserve ground-based astronomical observations? Not very good....
I'm working on a more extensive article, but among the "big four" constellations currently on orbit, China's GuoWang (aka Weixing Hulianwang Digui) is the most significant violator of the standard by a meaningful margin. (In fact, all four primary constellations are in violation of the recommended standard).
The graphic below presents the average visual magnitude of individual tracks of GuoWang satellites since 01 Jan 2026, as taken by the Russian MMT system. (Data comprised of 427 tracks with 299,225 observations).
Results summarized: These satellites on average exceed the maximum recommended brightness for their altitude by 2.96 visual magnitudes. Translating visual magnitude into a linear irradiance scale, or units directly related to the "digital counts" on a telescope's focal plane results in exceeding the brightness recommendation by 1524% !!!
Orbital data (satellite altitudes) courtesy of @S4S_SDA via @SpaceTrackOrg , used with permission per ODR 24-002-4.
Not a good story. Over the past year, China continues to abandon numerous upper stages in long-lived low earth orbit,* counter to best practices for the long term sustainment of space.
I initially sounded the alarm on this issue in April 2025, and further highlighted the issue in an August 2025 article and...the update is that things only continue to get worse.
For those not familiar, the total orbital debris mass is a key variable for the long term sustainment of space. There is broad agreement that abandoning rocket body upper stages in long-lived orbits is NOT a best practice. In fact, all the major space-faring nations have acknowledged this (e.g., IADC signatories).
However, as China's "mega constellations" launch rate increases, so does the number of abandoned rocket bodies in long-lived high LEO orbits.
Russia and the US dominate the number of rocket bodies remaining in such long-lived orbits, rooted in historical practices from decades ago with minimal orbital debris concerns (graphic, bottom panel). HOWEVER, China's upper stages are estimated to have much higher masses on average. Although the US has almost double such objects, China's total mass of such objects is 252 metric tons and increasingly rapidly vs the US total of 57 metric tons (and holding steady). It's acknowledged there are some uncertainties in PRC upper stage dry mass values (Graphic, top panel).
No matter, things are not going well.
* "Long-lived LEO" is defined here as having a min perigee height of 600 km and an orbit height less than 2000 km (to preclude HEO rocket bodies)
** Object mass estimate use @planet4589 's dry mass from the GCAT
*** Orbit data from U.S. Space Forces – Space (S4S) via space-track.org, used with permission per ODR 24-002-4.
1/n Thank you @heospace for facilitating "Positive ID" of a Chinese payload (OBJECT A - 57424) from this 2023 PRC launch with multiple payloads (launch 2023-104).
nitter.cf/heospace/status/205724…
HEO has a #NoUFOPolicy.
Objects we image leave with an identity and characterisation, as it is critical to identify space objects to maintain space and Earth safety.
For example, this object is currently listed as Object A in public tracking databases, a designation assigned to newly launched objects pending formal cataloguing.
HEO has imaged and characterised it as the Lingxi 03 communications satellite, a designation corroborated by publicly available information on the mission.
When identities and capabilities in orbit remain obscure, whether by cataloguing lag, sparse public data, or the absence of independent characterisation, operators work with an incomplete understanding.
Unknown no longer has to be a permanent state.
*Measured in the 2D image plane. Any extension into the image plane is not captured, so this figure represents a minimum. The true length may be greater.
2/n It's constructive to examine the optical signatures of all PRC objects associated with this launch (2023-104), simply identified as Objects A-F in the US public catalog (space-track.org). A total of 6 objects have been cataloged from the launch; however, none of the objects are identified by name (SATNOs 57424-47529).
Given HEO's NEI image of an object from the launch, it's constructive to examine the optical signatures of all objects associated with the launch.
"OBJECT A" has a median optical cross section (OCS) of 13.9 dBsm, or ~24 m^2 (derived via a diffuse sphere model with albedo of 0.2).
OBJECT A's optical cross section (OCS) is significantly larger than all of the objects from this launch for which optical signature data are available* (ref graphic).
* Optical signature data is open source courtesy of the Russian MMT system.
3/n @Skyrocket71 's page on the probable identity of OBJECT A -> space.skyrocket.de/doc_sdat/…
Military Space History #18: 1976: @NRO_gov Satellite Survivability
Mandatory reading for all @USSpaceForce Guardians, and my reminder that space was "born contested!"
It's been a while since my last "Military Space History" installment. This highlight comes courtesy of the NRO's annual "Sunshine Week" declassification and public release of historical documents, with this trove largely consisting of documents hitting the 50 year declassification milestone.
1/2
On July 7, 1976, President Ford issued National Security Decision Memorandum 333 (NSDM 333) "Enhance Survivability of Critical U.S. Military and Intelligence Space Systems." The growing dependence of the U.S. on satellite reconnaissance coupled with the growing Soviet ASAT threat prompted NSDM 333. NSDM called for the SecDef and DCI to balance the level of survivability of satellite systems commensurate with their mission importance.
The NRO's response was quantified via the NRO's "Survivability Enhancement Action Plan," with the study completed in October 1976. The declassified study is a treasure of information regarding the assessed Soviet counterspace threats at the time, and an assortment of options to "Protect and Defend" (today's vernacular) against these threats.
The full document in it's entirety may be downloaded here: nro.gov/Portals/135/document… (nro.gov URL)
2/2
#SpaceDomainAwareness #MilitarySpaceHistory #AlwaysContested #OurGrandparentsHaveBeenThereAndDoneThat! #ASAT
*** Yaogan-50 - China's First Retrograde LEO Satellite ***
On 13 Jan 2026 China launched Yaogan-50-01, its first LEO satellite in a highly retrograde orbit (ref graphic). While the payload is unknown, a probable contender is a synthetic aperture radar (SAR) system as the higher velocity relative to the earth's surface also serves to increase the spatial resolution(?).
Such a high inclination also provides improved revisit times time for lower latitude locations--such as the South China Sea.
(Orbit data from U.S. Space Forces – Space (S4S) via space-track.org, used with permission per ODR 24-002-4).
