Venera 8 Kosmos 482 descent craft reentry forecasts

Click diagram to enlarge

Last update: 11 May 2025 10:15 UTC 

* The last TUDAT nominal forecast is reentry on 10 May 2025, 6:39 UTC ± 1.5 hr *

* The TUDAT nominal postcast is reentry on 10 May 2025, 6:40 UTC ± 1.5 hr *

Venera 7 lander mock-up. The Kosmos 482 Descent Craft is probably similar. Photo: NASA

The risks involved are not particularly high, but not zero: with a mass of just under 500 kg and 1-meter size, risks are somewhat similar to that of a meteorite impact. A TUDAT reentry analysis to ground level suggests an impact speed (after atmospheric deceleration) of about  65-70 meter per second (~242 km/h), assuming the reentering lander did not break up or extensively ablate during reentry (see the diagram below: note the logarithmic scale of the x-axis). The kinetic energy at impact is similar to that of a 40-55 cm large (after ablation) meteorite fragment. As it will likely reach earth surface as only one single object, the risks involved are lower than for example those created by a Falcon 9 upper stage reentry, which showers multiple meter-sized objects over a large area (as we saw recently with the impact of Falcon 9 remains in Poland).

Click diagram to enlarge

The diagrams below shows the change in altitude of apogee and perigee over the past 1.5 years and the past 4 months: notably apogee has been coming down steadily, but in the past few months, perigee has started to come down too. Early May 10 around 00:35 UTC, the object was in a 166 x 120 km orbit, with apogee coming down by 70 km/day and perigee by 25 km/day (and these values increasing each day, see diagram below).

Click diagram to enlarge

Click diagrams to enlarge

The reentry is an uncontrolled reentry. Even close to reeentry, we cannot say with any degree of certainty when and where the Kosmos 482 Descent Craft exactly will reenter.

With an orbital inclination of 51.95 degrees [note: I initially erroneously stated 51.7 here], the reentry can occur  between latitude 52 N and 52 S.

TUDAT, the TU Delft Astrodynamics Toolbox is open source, multi-platform Astrodynamics software developed and maintained at the Aerospace faculty of Delft University of Technology (TU Delft) in the Netherlands (where I work). The TUDAT script we use for our analysis is here, while the TUDAT software itself is available here.

The Kosmos 482 Descent Craft is probably similar to the descent craft of Venera 8 (which was launched only a few days earlier in 1972). Literature values suggest that the object is about 1 meter in size and semi-spherical, with a mass of ~495 kg. 

Using our TUDAT model and a 1-meter diameter, and the NRLMSISE00 model atmosphere with historic space weather data, we find that the orbital evolution of  the object from mid-1972 to early 2025 is actually best matched when we use a mass of 480 kg, 15 kg less than the literature value. All our forecast predictions are therefore done using a mass of 480 kg. 

For our forecasts we employ the NRLMSISE00 model atmosphere, and historic spaceweather data plus estimated future space weather (solar flux). Orbit updates for each run are sourced from the US Military tracking network CSpOC (so as a note: our forecasts are not based on our own tracking data. They are based on our own custom reentry model developed at Delft University of Technology, with external tracking data from CSpOC as input).

Click diagram to enlarge

The diagrams in top of this post and below (which I will periodically update) give the evolution of our reentry predictions, based on orbits issued for the object since November 2024. Over the past half year, the model has consistently pointed to reentry within a few days of 9-10 May 2025. 

The latest nominal forecasts currently center on early May 10, but are still fluctuating with each orbital update. Early May, there was a short-lived tendency in the model runs of a shift towards a later time of reentry (i.e. May 11 rather than May 10), as can be seen in the below diagrams and the table near the end of this post. But lately, the new forecast runs have been returning to nominally May 10. 

Click diagram to enlarge

Click diagram to enlarge

The brief shift towards a later date in the early May model runs was due to space weather forecasts underestimating future solar activity at that time. I had started to note this (when comparing earlier forecast solar flux values to actual solar flux values for the last days of April  and the first days of May) and already expected the nominal forecasts to return to May 10, as they now indeed have done.

This highlights the influence of uncertainties in estimated future solar activity on the forecasts. Future solar activity is not well predictable. Even the best reentry models will be off in their forecast if actual solar activity in the window between the moment of forecast and the moment of reentry develops differently than the predictions. Solar flux variations are an important driving factor of short-term variations in density and extent of the upper atmosphere. The latter determine how many drag the object experiences over its orbit, and with that how quick the orbit decays. Stronger solar activity will mean an earlier reentry, lower solar activity a later reentry.

Of course, at this point the uncertainty in the forecast is still +/- 1.5 hours. Yet, the uncertainty window has now decreased to the point that we can rule out certain parts of the world: Africa is safe. So is Japan, East Asia, and the USA.

The map below gives the trajectory of the object over the current uncertainty window of the TUDAT reentry forecast (red dots are cities with over 1 million inhabitants, between latitude 52 N and 52 S). In our model the spacecraft could have reentered anywhere along the blue line:

Click map to enlarge

CSpOC, the US military tracking network, has started to provide TIP (Time of Impact Prediction) messages for the object since May 6. They are depicted as red circles in the diagram earlier in this post.

The last orbit update published by CSpOC has epoch 10 May 2025, 00:36 UTC, i.e. dates from about 6 hours before the time we think it actually reentered. There are later radar detections from Europe, per ESA, dating to as late as 6:04 UTC, but no orbit based on that has been published.

TUDAT forecast:              10 May   06:39 ± 91  min UTC

TUDAT postcast:              10 May   06:40 ± 91  min UTC

Aerospace Corp forecast:     10 May   06:29 ± 120 min UTC

CSpOC TIP postcast:          10 May   05:32 ± 12  min UTC *

* this cannot be correct given that a positive radar detection from Germany at 6:04 UTC was reported by ESA.

note: forecast = issued before the reentry; postcast = issued after the reentry after re-analysis.

ESA reports that they had a positive radar detection of the spacecraft, still on-orbit, at 6:04 UTC while it was passing over Germany (presumably with the TIRA radar); and a negative detection one orbital revolution later, at 7:32 UTC. This implies reentry during the window 6:04 - 7:32 UTC. Five of the forecasts fall in that window: our TUDAT forecast, and those by RosCosmos, ESA, the Aerospace Corporation, and also EU-SST when taking the error margins on the latter into account.

Roscosmos, the Russian Space Agency, on Telegram states reentry at "6:24 UTC" over the Indian Ocean. That is not too far (15 minutes) from our latest TUDAT model results. Three remarks: (1) this is not a reentry detection but likely another model result (just as the others), based on an earlier groundbased detection during a pass over presumably southern Russia. (2) It does not come with a stated uncertainty window: is that 10 minutes, 30 minutes, an hour? (3) It remains a question how serious one should take Russian State statements these days as sometimes pragmatic considerations (such as deliberate denial of responsibility or risk) are leading. 

While many news media seem to treat the RosCosmos announcement as 'authoritive' and the 'most accurate' or 'final' say on the matter, there is in reality no clear reason to do so. It is not clear at all whether the RosCosmos position is more accurate than the other model estimates, and how meaningful the stated positions and time are given the lack of error margin information.

A final accurate TIP from CSpOC has not yet appeared (and might not appear if they have no space-based detections of the reentry fireball). CSpOC sometimes, several hours to a day after a reentry, publishes a very accurate (with quoted +- 1 minute uncertainty) final TIP which Jonathan McDowell and I believe is not based on a reentry model, but on space-based (SBIRS satellite) detections of the reentry fireball, hence the accuracy. They have not issued such a TIP so far for this reentry, unfortunately. Note that their last issued TIP cannot be correct, given the reported positive radar detection of the spacecraft passing over Germany at 6:04 UTC.

This is how the nominal reentry points have been placed by various organisations, each based on their own modelling:

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It is clear that the assessments spread. Ignoring the clearly incorrect CSpOC TIP, the other models all suggest reentry over either southwest Asia or the Indian Ocean. My verdict is that the latter area is the most likely place.

Below is the evolution of the reentry forecast from our TU Delft TUDAT model in tabular form, latest forecast at the bottom. Please take note of the uncertainty values listed in the last column!

The 'postcast' value is a re-run of the model after-the-fact based on the last published orbit and the actual rather than estimated space weather of May 10.

An added note: about that parachute....

To muddy the waters further, a story is spreading that the parachute of the landing craft might already have deployed in space. This is based on telescopic imagery purportedly showing this.

I have strong doubts that the imagery in question shows any meaningful detail. The imagery has the same origin, and the same problems attached, as the imagery I discussed in 2022 in my Space Review article. I think the "detail" is the result of camera/telescope shake and atmospheric distortion.

This post has been updated with new forecasts and additional background information several times