New video of Intelsat 29e satellite reveals dramatic “anomaly” | Hacker News Reader

New video of Intelsat 29e satellite reveals dramatic “anomaly”

arstechnica.com

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I’ll just leave this here: https://spacenews.com/russian-satellite-maneuvers-silence-wo...

Extremely fascinating, thank you.

Very cool video, never seen anything like it. What sort of telescope is used to capture imagery like that?

I'm impressed as well. Are there companies that constantly take video footage of satellites for monitoring?

FTFA:

"However, new data from ExoAnalytic Solutions, which has a network of 300 telescopes around the planet to track satellite movements in geostationary space, shows the situation has gotten markedly worse."

Apparently, there are.

It doesn't take an advanced telescope, and it doesn't even need to track (much) because the satellite is geostationary.

Here's what the ISS looks like from Earth in an amateur telescope. The Intelsat appears as a dot because it's smaller and much farther away.

https://www.themarysue.com/iss-shuttle-in-daylight/

Orbital debris from India's anti-satellite test?

https://www.theguardian.com/science/2019/apr/02/a-terrible-t...

No, it's extremely unlikely that debris would be propelled from low-earth orbit and hit a tiny satellite over 35000 km away.

Intelsat 29e was in the geostationary orbit at an altitude of 36000 km. The Indian ASAT test was at an altitude of 300km. For any debris to reach that altitude, the explosion has to boost its velocity by 2 to 3 km/s. This is highly unlikely.

For a debris the mass of a screw, it's not that far fetched. Moreover, orbital collision can launch it with an enough velocity to reach GEO orbit retrograde. You need "just" 10 to 15 kJ of kinetic energy. A retrograde collision will then be able to liberate few times more energy.

https://instacalc.com/42836

If that happened anywhere close to the apogee of the Indian ASAT test debris, and in same ecliptic, it's very likely it

this would be like throwing a dart at a dartboard on the moon.

That figure of 10 to 15 kJ can be very misleading about what it takes to propel something to such speeds. Put into 'TNT equivalent', it would take the entire energy of 50g of TNT to boost a 100g bolt by just 2 km/s. It's difficult to concentrate that much energy per mass in an explosion (which is leaky). To add further, most ASATs (including the Indian test) doesn't use explosives, but make a direct hit (hit to kill) from a suborbital trajectory (one that has much less energy than an orbital interceptor). The boosting comes mostly from fragmentation mechanics.

The satellite will still fragment with some fragments getting boosted up to a higher velocity. In addition, the propellants on the satellite and the kill vehicle might add velocity to the fragments too - though arguably less energy than if it was TNT. So, previous studies on US and Chinese ASAT debris cloud can be considered for a fair assessment. The Chinese test was at a higher altitude of 865km and US test was at a similar altitude. 'Gabbard plot' of these debris show the maximum altitude to be only around 3900 km for both tests. There could be untracked particles at higher orbits, but remember that the velocities of the debris is a random distribution (not sure which one) that tapers at extreme values. Odds of any debris crossing geostationary orbit is very low.

There is one additional significant point to consider. Boosted orbits mostly retain the altitude at interception (it's the diametrically opposite part of the orbit that gets affected). This is evident from the Gabbard diagram, where apogee and perigee plots intersect in cross shape with a horizontal line at the altitude corresponding to intercept altitude. This means that most debris come down to atleast 300km. Since the drag at this point is significant, the apogee (maximum altitude) of the debris would decay rapidly - thus mitigating risk to higher satellites. With that odds, a debris crossing geostationary orbit could more likely be from some previous in-orbit explosions than from any ASAT test.

Ref: https://sattrackcam.blogspot.com/2019/03/debris-from-indias-... https://sattrackcam.blogspot.com/2019/04/why-even-low-altitu... https://celestrak.com/publications/AMOS/2007/AMOS-2007.pdf

That's a proper argument. I did not think that far

Not even remotely possible. None of the sources in the India explosion are energetic enough to move debris that high. By a large margin.

TL;DR: The anomaly includes propellent out-gassing events from the spacecraft, creating a dissipating halo and several pieces of debris. The satellite is now drifting at 1 degree a day. Cause as yet unknown although an external impact (debris or micro-meteorite) is hypothesised.

Now it's a geostationary comet.

I have heard about a lot of debris in space. How much is there in general and how much is at that height?

I wonder if there are simulators that can predict the likelihood of collisions.

Also how common are meteorites and things coming from space? And what are the chances of being hit by those?

I am guessing a large object like the space station has a bigger chance of being hit by something.

My great concern is that satellite fission may cascade, enveloping the Earth in a debris cloud and taking away access to space.

AKA Kessler syndrome

https://en.wikipedia.org/wiki/Kessler_syndrome

Kessler syndrome is not a big concern for GEO, which is quite a "lazy", well organized and sparsely populated orbit where high relative velocities are rare, compared to highly crowded synchronous polar orbits, especially the lower ones.

Good point. I infer that any cascade impact from i29e will be felt in lower orbits.

The debris fields are in considerably lower orbits so its unlikely any material has reached geo-synchronous altitudes. Meteorites are a problem but the most common are very small. Yes, they can cause damage if a critical part of the satellite is hit but usually, they're mostly harmless. Larger meterorites are much rarer so the probability of an impact is quite small.

> how much is at that height?

Not a lot. Most of the debris is located at much lower orbits. The total number of satellites in GEO is mostly limited by the angular resolution of customers' antennas (= dish size). Also, it costs a lot to launch something to GEO, and it's in the middle of the outer Van Allen belt (a tough environment, radiation hardening is an absolute requirement). So it's sparsely populated with large expensive spacecraft the size of a bus, orbiting Earth at predictable intervals. Dead stuff drifts away since it's not a stable orbit.

> I wonder if there are simulators that can predict the likelihood of collisions.

Most gravitational dynamics frameworks or standalone software will do.

> how common are meteorites and things coming from space? And what are the chances of being hit by those?

Quite common, but the near-Earth space is really big, and GEO in particular is sparse enough for the strikes to be rare.

>I am guessing a large object like the space station has a bigger chance of being hit by something.

Yes, and both Mir and ISS were hit many times.

That video is just rough to watch for me as an engineer. Poor little satelite..

I think it's funny how "not possible" or "not even remotely likely" answers are just dismissing the possibility of this being debris from low earth orbit.

Sure, it's unlikely. But unlikely bugs do happen in computation, too. We _cant_ know.

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