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Here’s a link to the real-time video clip from UK004E. The cloud starts in northern Capricornus and then moves up into Aquila. You can see a number of the deployed spacecraft ahead of the cloud and a brighter object in the cloud. The brightest dot, towards the end, is the venting second stage itself. Mel’s video linked above shows the individual events in far higher resolution and I assume that the significant brightening of the second stage around 00:12:45 is the large venting event shown on Mel’s video.
https://nickdjames.com/Spacecraft/20250524_propvent/UK004E_20250624_001126_ndj.mp4
The final spacecraft deployment was the Mission Possible re-entry experiment at T+2:43:53 which is just before 00:09 UTC and the first sign of the cloud is at around 00:11:30 so only around 2.5 mins later.
Stan,
According to the Space-X video here:
https://www.spacex.com/launches/mission/?missionId=transporter14
The second stage de-orbit burn occurred over north Africa starting at T+2:40:16 and it lasted a few seconds. Launch was at 21:25:00 UTC so that means that the burn was over by 00:06 UTC, before we saw the stage come over the UK. Three minutes later it deployed a re-entry demonstrator called Mission Possible and then started the passivation with thruster firings and venting residual propellant which is what we saw.
I have video from my SE pointing camera (UK004E) showing the stage rising out of the Earth’s shadow in the SSE with with the venting starting around 00:11:46 UTC.
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Mel – That’s a brilliant video and it shows the various thruster pulses and the main burn very well. What equipment did you use?
Steve – You were in bed? So was I. I thought you had an army of Seestars permanently monitoring the sky…
Cees Bassa confirms that it was Transporter 14. Presumably the upper stage deorbit and passivation.
I don’t yet know what it was but it certainly looks like propellant venting. Prompted by your post I checked my cameras and did pick it up. The screengrab here shows it and the video at the link below shows it slowly moving downwards towards the northern horizon.
https://nickdjames.com/Spacecraft/20250524_propvent/propvent2_20250624_001530_ndj.mp4
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That is very sad news. I remember seeing Terry and one of his early cameras at an Exhibition Meeting in the early nineties. I bought an early SX and was astonished by its capabilities. Terry was always incredibly helpful.
My first light with the SX was on 1994 September 1. The image of M57 doesn’t look much now but it was a revelation then. The chip was 510×256 pixels, the pixels weren’t square and the field of view was tiny but the sensor was much more sensitive than film and there was no messing around with horrible chemicals afterwards.
Terry led the way in the UK and changed my (astronomical) life completely.
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This interesting paper has jus been posted on Archiv:
https://arxiv.org/pdf/2506.11217
The authors consider the potential effect of a lunar impact of 2024 YR4 on 2032 December 22. They conclude that it could temporarily increase the flux of mm sized meteoroids in near-Earth space by several orders of magnitude. This could be bad news for spacecraft in low-earth orbit but might give us a nice meteor shower.
The probability of a lunar impact is currently around 4% and the high end of their flux predictions require some relatively unlikely alignments to happen but it is definitely an interesting read.
The latest prediction from Marco Langbroek is that re-entry will occur around 06:30 UTC tomorrow, May 10, with an uncertainty of +/- 4.1 hr:
https://sattrackcam.blogspot.com/2025/04/kosmos-842-descent-craft-reentry.html
The latest TLE from space-trak (dated March 9.655) has perigee down to 127 km. The spacecraft has passes over the UK on May 10 as follows (times are UTC):
04:34 – Low elevation in the southeast.
06:05 – Almost overhead
07:36 – Almost overhead
09:06 – Low in the southwest.All of these are in daylight so if it does re-enter over the UK we are unlikely to see it but, if the sky is clear it might be worth looking when it comes over.
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Unfortunately we don’t have any night-time passes of this spacecraft coming up.
This page will get updated as the TLEs get updated:
https://aerospace.org/reentries/6073
The current re-entry prediction is 2025 May 10 04:42 UTC +/- 19 hours.
The conditions were slightly better low to my northwest this evening and the comet is more obvious in this stack:
https://nickdjames.com/Comets/2025/2025F2/2025f2_20250429_203939_ndj.jpg
My image of this nebula at 0.56 arcsec/pix taken this morning (April 29.06) shows quite a bit of detail in the brighter part of the nebula. Certainly an interesting object to follow.
https://britastro.org/observations/userimg/20250429_202133_f7c854744716.jpg
I got a possible detection of the remnants of this comet last night (April 28.86) from Chelmsford, low in the bright evening twilight.
https://britastro.org/observations/observation.php?id=20250429_063941_2990db2ceeed4e3a
Yes, the ion tail is straightforward since it consists of ions accelerated away from the coma entrained in the solar wind and so it extends radially along the anti-Sun vector. That is easy to calculate.
The dust tail is an orbital mechanics problem. Each dust grain leaves the nucleus at a particular velocity and then it gets accelerated, mainly by solar radiation pressure. The acceleration depends on the mass of the grain and its cross sectional area. Because of this acceleration, each grain moves in a slightly different orbit to the nucleus but the difference in velocities is relatively small and so the grains spread out from the nucleus in the comet’s orbital plane. There are some good online demonstrations of how this is modelled:
https://www.comet-toolbox.com/FP.html
https://hdr-astrophotography.com/comet-tails-simulations/One of the most spectacular dust tails of recent times was that of C/2006 P1 (McNaught):
https://britastro.org/cometobs/2006p1/thumbnails.html
A detailed description of how that was modelled is here:
https://www.sciencedirect.com/science/article/pii/S0019103518301192
Last night (April 21/22) was clear in Chelmsford and I got 102 single station Lyrids along with 45 sporadics, 5 alpha Virginids and 2 eta Aquarids. As expected activity peaked in the early morning hours with events every few minutes from 0300 UT to dawn.
Peter Carson managed to image C/2025 F2 (SWAN) from Spain on 2025 April 21.19. His image shows a diffuse, elongated, coma with no distinct photocentre and a brighter bar of material in PA 330 degrees.
https://britastro.org/observations/observation.php?id=20250421_202852_3fb2d1e648d24ca4
The ephemeris position is at the head of the bright bar so this consists of dust that has flowed tailward from the disrupted nucleus.
The comet’s orbit implies that this is a dynamically old object so it has previously survived perihelion. It wasn’t so lucky this time.
I’m not able to get onto the comet with my main telescope until it clears my house roof, by which time the sky is very bright, but here is an image from this morning (April 18.17). There is apparently no distinct photocentre any more.
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Yes, it does look very much as if this comet has expired. There are not many recent magnitudes on COBS but it seems to have stalled at around 8th magnitude and then faded. I haven’t managed to observe it for a few days due to the weather.
Grant – Are you an hour out? The sky was hardly dark at 20:00 UTC and my cameras show the aurora becoming active around 21:08 UTC.
