Kosmos 2495 Re-Entry
September 9, 2014
A Russian film-return reconnaissance satellite or a component thereof may have re-entered the atmosphere over the United States last week, witness reports and orbital data suggests. Contrary to reports from U.S. observers, the Russian Ministry of Defence claims that none of their satellites re-entered over the United States, supported by video that shows the satellite in question re-entering the atmosphere over Kazakhstan (videos at the bottom of this page).
The puzzling incident took place last Tuesday, September 2 in the skies over Colorado and Wyoming. Around 10:30 p.m. local time (4:30 UTC on the 3rd), a bright fireball was observed from central Colorado into southern Wyoming, perhaps visible from as far as New Mexico, South Dakota and southern Montana. Over 30 witness reports of the event were published by the American Meteor Society. The fireball made local news last week, however, no photos or video of the event were published.
A number of witnesses, including experienced sky-watchers reported that the object was moving much slower than a usual fireball, some immediately conclude that what they were observing was the re-entry of a piece of space debris.
Object over New Mexico during the early Stages of Re-Entry (Credit: Thomas Ashcraft)
Most likely already immersed in plasma, the tumbling object experienced the first stages of re-entry over New Mexico.
Reports submitted to AMS are in good agreement on the time of the event and most observers were able to track the object for a considerable period of time which supports the theory of a decaying satellite.
Reported observations of the Fireball from New Mexico, Colorado, Wyoming, South Dakota and Montana (Final viewing directions in red)
Some witnesses were able to see the re-entering object for thirty seconds or longer, reporting that the object was moving slowly. Fragmentation and an increasingly longer trail were reported by the majority of witnesses, describing that the object first split in two fragments, one smaller and one bigger before a complete break-up of the objects followed by a slow fade-out of the glowing fragments.
The longevity of the event and the low velocity of the object suggests that it was indeed a re-entering spacecraft – most likely a satellite flying in a highly inclined orbit, based on the observed track from south to north.
Dan B. observed comet Jacques from Alamogordo, New Mexico using image stabilized binoculars when noticing a bright object entering the field of view. In his report, he described the object to be orange in color, tumbling at a rate of one revolution per second with a vivid smoke trail.
Notably, he also states that the object was much slower than a meteorite. Very little fragmentation was seen from his perspective as the object flew from zenith to the horizon.
Dan B.(New Mexico) viewing direction & Kosmos 2495 Ground Track
Looking at the map of witness reports, this observation lines up perfectly with observations made from Colorado who picked up the object after passing over Dan B.’s location – this confirms that he observed the extremely rare sight of a satellite in the early stages of re-entry – showing a trail of smoke without experiencing break-up yet.
The report of discernible tumbling ahead of re-entry, the duration of the visible entry process and length of the ground track with confirmed observations indicates that the object was of considerable size.
Re-Entry seen from Cloudbait Observatory (Credit: Cloudbait.com)
Animation of frames acquired at Cloudbait Observatory from 4:34:04 to 4:34:26 UTC clearly showing the south-north motion of the object
Looking for candidates that match the observation, one can turn to re-entry data provided by U.S. Space Surveillance. For September 2 and 3, there are only four decay messages: a small piece of satellite debris, the 1U INVADER CubeSatellite, the two-metric-ton Yaogan 5 satellite from China and the Russian Kosmos 2495 satellite launched earlier this year. Considering the size of the fireball, the debris and CubeSat can be ruled out immediately, leaving only Yaogan-5 and Kosmos 2495. The re-entry of Yaogan 5 was observed by U.S. assets and can be pin-pointed with a certainty of one minute showing a decay time of 20:30 UTC on September 2 while passing over the southern Indian Ocean.
Yantar Photoreconnaissance Satellite
This only leaves Kosmos 2495 – a Russian film-return satellite delivered to orbit on May 6, 2014 atop a Soyuz rocket launching from the Plesetsk Cosmodrome.
A relic of the soviet era, the Kobalt-M satellites originate in the Yantar photoreconnaissance project that dates back to 1964. Kosmos 2495 was likely the second to last of its kind to fly into space since Russia has started the operation of electro-optical satellites that downlink acquired imagery to the ground instead of returning physical film to Earth. Operating from a very low orbit of around 200 Kilometers, the satellite can obtain high-resolution imagery of ground targets.
Kobalt-M satellites measure 6.3 meters in length and 2.7m in diameter with a launch mass of 6,600 Kilograms, including a 900kg fuel load that is expended during the mission to maintain the satellite’s extremely low operating orbit. To return film to the ground, the satellite uses two small return capsules that are separated from the satellite and land in Russia. A third capsule is part of the main satellite body to return at the end of the mission when the spacecraft performs a targeted re-entry to land in a pre-determined location within Russian territory.
Kosmos 2495 Ground Track
Looking at the last known orbital parameters from September 2 at 17:11:55 UTC, Kosmos 2495 was in an orbit of 201 by 246 Kilometers inclined 81.4 degrees. This data confirms two items of interest – the satellite was still in orbit on September 2nd but re-entered before September 3rd 7:48 UTC which is the time stamp of the Kosmos 2495 decay message.
Second and most importantly, the satellite was in an orbit that was not close to a natural, untargeted decay. (For reference, the propagation software SatEvo shows that the orbit had an approximate lifetime on the order of two weeks.) This indicates that the satellite’s re-entry was the result of a propulsive event – either a retrofire or a propellant/pressurant leak supplying negative delta-v.
Plotting the satellite’s ground track for the night of September 2nd shows that the Kosmos 2495 satellite made a pass over New Mexico, Colorado and Wyoming at the reported time of the fireball.
Both the ground track and the timing of the event are in good agreement with the last orbital data of Kosmos 2495 that would have passed over the border between New Mexico & Colorado at 4:36:25 UTC if it had still been in the orbit it was observed in at the 17:11 Epoch. An early arrival of approximately three to five minutes is plausible as the result of the reduction in period from a propulsive event. [This section was corrected on September 9, 15 UTC to correct for a date error.]
Nevertheless, the possibility of Kosmos 2495 landing nominally and the Colorado event being an unrelated re-entry of a slow meteor lining up in location and time with the predicted ground path of the satellite still exists and can only be ruled out with conclusive evidence.
Observations & Kosmos 2495 Ground Track
Observer locations & last seen viewing directions (red) & Kosmos 2495 Ground Track (yellow)
With a Russian satellite weighing 6.6 metric tons, it is safe to assume that a number of components survived re-entry and reached the ground. As a relic from the older days of satellite development, the Yantar bus employs a more robust construction with heavier structural elements which has some implications on the re-entry process as dense components are known to survive longer in the high-temperature entry environment than the conventional light-weight structures used in modern spacecraft. Additionally, the film capsule of the spacecraft was specifically built to survive re-entry and protect the images it carried.
According to a post on the SeeSat-L message board, the re-entering spacecraft created a debris cloud that was seen drifting for over thirty minutes on Doppler radar images from Denver and Cheyenne.
Doppler Image showing the Debris Cloud (Source: SeeSat-L)
Doppler image of the debris cloud well after the event, located east of the satellite ground track. (Cross-track difference between the orbital track and the debris cloud may be a sign of a plane change performed by the satellite as part of a propulsive event pre-entry. Winds from the west may have contributed as well.)
Usually, dense components of re-entering satellites can travel 800 to 1,300 Kilometers downrange from the orbital decay point. Their journey back to Earth is influenced by atmospheric properties such as crosswinds. Assuming that orbital decay occurred on the border of Colorado and New Mexico, components of the satellite potentially flew as far as the Canadian border.
All this leaves the question why the Kobalt-M satellite would make an apparent crash landing in North America instead of performing a targeted deorbit burn to return the film to Russia. A targeted September 2 landing in the Orenburg region, Russia would have had to occur around 18:25 UTC based on the latest orbital data available for Kosmos 2495.
It is nearly impossible that Russia would intentionally crash its satellite on American territory, especially in times when tensions between Russia and the west are mounting due to the ongoing unrest in the Ukraine. No comments on the incident were made from either side. Using space and ground-based assets, USSTRATCOM has most likely tracked the re-entry in real time – identifying the spacecraft and monitoring the trajectory of debris.
NASA study on surviving components of re-entering UARS Satellite & potential downrange distance from 80-Kilometer decay altitude
The most probable explanation for the unexpected re-entry of Kosmos 2495 would be a malfunction of the satellite that led to an incorrect timing of its deorbit – possibly a software error or a partial retrofire performed earlier in its last orbit leaving the satellite in a very short-lived orbit resulting in an untargeted decay.
Looking at the data, it appears very likely that the re-entry was the result of a sudden change in velocity – such as a retrograde burn. Had the satellite lowered its orbit earlier, perhaps several hours before the event, it would have been orbiting well ahead of its prediction based on the latest Elset which was not the case.
Well-respected satellite tracker Marco Langbroek brings up an interesting theory: “This reentry happened some 5 minutes after the satellite passed its [ascending] node at 4:27 UT. So I wonder whether for example an intended orbital plane change (which you normally do by firing a booster in one of the nodes) went wrong and it was sent plummeting down instead.”
Satellite Tracker Ted Molczan posts his initial analysis here, detailing the possible scenarios of what was seen in the Kazakh & American skies last week.
Igor Lissov dug up a number of videos uploaded to the Internet showing a re-entry event taking place over the Atyrau region, Kazakhstan. These videos were all uploaded on September 2nd or 3rd. Observations reported from Kazakhstan around 18:15 UTC on September 2nd are a very close match with the calculated time and ground track of a controlled re-entry of Kosmos 2495 for a landing of the film capsule in the Orenburg region, Russia.
The videos show a bright object flying in front of a larger disintegrating object – indicative of the film capsule on a ballistic entry path pulling out in front of the Service Module of the satellite that broke up in the upper atmosphere. This supports the claims of the Russian Ministry of Defence, denying that Kosmos 2495 burned up over the United States.
Re-Entering object over Kazakhstan, possibly the film capsule flying in front of the disintegrating Service Module
The apparently successful return of Kosmos 2495 obviously raises the question what type of object re-entered over the United States in the night of September 2nd, closely matching the path of the Kosmos satellite in position and timing? Which sizable object was seen tumbling in a cloud of ionized plasma from witnesses in New Mexico before being observed across Colorado, visible for thirty seconds or longer? A slow meteor or another spacecraft re-entering as a huge (but possible) coincidence, or perhaps a component that separated from Kosmos 2495?
One possible theory is that the Kosmos satellite released the re-entry vehicle in its last known orbit (Epoch 17:11) from where the cone-shaped entry vehicle independently conducted a targeted deorbit burn for a landing in Russia while the Service Module remained in orbit to be disposed via re-entry over the Pacific Ocean at the first suitable opportunity. An error in that last burn of the Service Module could have caused a later re-entry and also explain the observed timing difference of just a few minutes to predicted passes over the U.S. – But this raises the question why the lone Service Module was not tracked in orbit during more than ten hours of free flight.