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The death of a weather satellite as seen by SDR (hackaday.com)
92 points by guiambros 61 days ago | hide | past | web | favorite | 20 comments

An aside: I’m pretty sure I saw the death of a satellite in full visual glory, three nights ago. Was watching for meteors, and a large bright blue streak came in heading due south, looking slow and shallow, and left a smoke trail visible through binoculars. Same plane as I see a lot of polar orbits on from here. I’ve searched to see if I could find anything known that was deorbiting then, but couldn’t. The fireball would have started somewhere over Spain (was looking south from France), probably ended in South Atlantic. I thought I’d mention it here, as if anybody has a clue, it’ll be you lot.

Meteors can produce smoke trails and I have seen them create them!

https://www.youtube.com/watch?v=tbpiOWs6zPU (note: not my video, just one I googled)

Three nights ago was near the peak of the Perseids meteor shower, too.

Here in Australia you can be a long way from light pollution.

On a dark (new moon) night, I've almost always been able to spot "shooting stars" aka meteors within less than 20 minutes if I lie on my back and look at the sky.

The smoke is interesting though!

Next one will be Meteor M2, it's experiencing malfunction after malfunction, breaks my heart.

The problem is believed to be the spinning mirror which scans the image sensor's viewpoint across the Earth. The motor driving the mirror has a problem, so it doesn't spin consistently any more. It is supposed to spin at 360 RPM.

Could it be possible to spin the entire satellite and get intermittent coverage and reception?

Satellites usually need to point their solar panels and high-gain antennas properly in order to stay powered to be able to communicate with ground stations, although this particular satellite seems to have been unable to use its high-gain antenna anyway and relied on an omnidirectional one anyway. Another issue would be thermal management as it is possible that not all parts of the satellite were designed to deal with direct sunlight. I would be more worried about all the sensors, though. The days of secondary electron conduction tubes [1] might be long over, but many instruments still prefer not to be pointed directly at the sun.

Speaking of those other sensors, spinning the satellite would mean pointing all of them away from where they are supposed to be looking – not necessarily a net win.

Finally, trying to spin the satellite at anything approaching 360 RPM might end up dramatically shortening the mission [2].

[1] https://en.wikipedia.org/wiki/Apollo_12#EVAs

[2] https://youtu.be/AqeJzItldSQ?t=90

EDIT: In case you do not feel like watching the video, [2] shows a Little Joe II rocket (https://en.wikipedia.org/wiki/Little_Joe_II) breaking up due to an excessive roll rate (around 56 RPM) (https://en.wikipedia.org/wiki/A-003).

>trying to spin the satellite at anything approaching 360 RPM might end up dramatically shortening the mission

A recent, quite a spectacular example of that was the Hitomi X-Ray observatory which went into uncontrolled spin due to a faulty inertial unit.


Why boost-up to a graveyard orbit rather than "booting-down" to decay and presumably burn up on re-entry?

As other commenters mentioned, it is just too far away to do that.

To give you a sense of scale, if you reduce Earth to the size of a basketball, low earth orbit (space station, starlink, etc) would be less than a quarter inch above the surface of the basketball. Geosynchronous orbit is a ring around the equator 26 inches above the surface of the basketball.

This is also why Starlink is incomparable to existing satellite internet solutions.

There's a nice visualisation of the different orbits at http://stuffin.space

Wow. Thanks for that, what a great visualisation, and updating too!

Edit: This is the satellite being talked about in the article http://stuffin.space/?intldes=1998-030A

That site is fantastic, thanks! And it also indexes debris; just enter "DEB" into the search box to get data on all known debris in orbit.

It's not in geosynchronous, though, it's in low earth.

Because it takes a lot of fuel to go from GEO to an orbit that would touch the atmosphere. It is not like a low orbit where a small perturbation will easily bring the satellite close enough to the atmosphere so that it brakes naturally.

According to this graph [1], you need about a third of the delta-v budget it took to get to GEO in order to get back into LEO.

[1] https://en.wikipedia.org/wiki/File:Delta-Vs_for_inner_Solar_...

That chart is for circular orbits AFAIK; you need less than half of that to lower one apsis to touch the atmosphere, and the air will do rest of the work. Still probably not worth it.

True, although it's not in a GEO orbit.

Apart from what others have mentioned, they "boost up" to a graveyard orbit instead of down to avoid old satellites or their potential debris clouds from eclipsing Earth for their replacements or posing a collision risk on the geostationary transfer orbit.

It's not in geostationary orbit though.

It might be too high. It takes rather a lot of energy of change orbits and it might not be possible to get it close enough to earth for drag to take over.

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