Author Topic: What Happened to RISAT-1?  (Read 1880 times)

Offline sanman

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What Happened to RISAT-1?
« on: 04/09/2019 07:48 pm »
India's RISAT-1 was lost a little over 2 years ago on September 30, 2016.

What are the speculations on what might have caused the loss of this satellite?

https://en.wikipedia.org/wiki/RISAT-1

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Incidents

On 30 September 2016, Joint Space Operations Center identified a debris generating event near RISAT-1.[14][15] The event created 16 pieces out of which 15 decayed and one was catalogued on 6 October 2016 under NORAD ID: 41797 and COSPAR ID: 2012-017C and decayed on 12 October 2016. Cause of this event remains unknown. A month later on 3 November 2016, RISAT-1 data was declared unavailable on ESA's Copernicus Space Component Data Access portal due satellite outage. Satellite was experiencing anomalies but ISRO denied they were related to fragmentation event.[2][16]


References:

https://twitter.com/18SPCS/status/783812350860140544

https://spacedata.copernicus.eu/web/cscda/news/archive/-/asset_publisher/MUXrdlTX10kW/content/risat-1-unavailability

https://orbitaldebris.jsc.nasa.gov/quarterly-news/pdfs/odqnv20i4.pdf#page=4

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The Indian Radar Imaging Satellite (RISAT)-1 Earth observation satellite experienced a possible fragmentation event on 30 September 2016 between 2:00 and 6:00 GMT due to an unknown cause.

What exactly is a "fragmention event"? Does it imply some sort of spontaneous disintegration - and if so, then how likely is that for a satellite of RISAT-1's construction?
« Last Edit: 04/09/2019 09:13 pm by sanman »

Offline K210

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Re: What Happened to RISAT-1?
« Reply #1 on: 04/10/2019 03:16 am »
It was struck by orbital debris some years ago

Offline sanman

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Re: What Happened to RISAT-1?
« Reply #2 on: 04/10/2019 05:08 am »
It was struck by orbital debris some years ago

I always thought that debris were tracked along with their potential future collision intercepts.

The references cited above use the word "fragmentation" rather than orbital collision specifically, while also saying it was due to "unknown cause".

As per that last citation from NASA above, the approximate time of the event was "30 September 2016 between 2:00 and 6:00 GMT"

Is there any online calculator/app available to show the position of where the satellite would have been above the Earth at that date and time range?
« Last Edit: 04/10/2019 05:54 am by sanman »

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #3 on: 04/10/2019 10:03 am »
It was struck by orbital debris some years ago

I always thought that debris were tracked along with their potential future collision intercepts.

The references cited above use the word "fragmentation" rather than orbital collision specifically, while also saying it was due to "unknown cause".

As per that last citation from NASA above, the approximate time of the event was "30 September 2016 between 2:00 and 6:00 GMT"

Is there any online calculator/app available to show the position of where the satellite would have been above the Earth at that date and time range?

RISAT-1 was operating from a 536-km orbit, so its period would be ~95 minutes. Its orbit would take it over a given longitude at 6 and 18 hours local time (LTAN).

Since the fragmentation is quoted as occurring at 4:00▒2h GMT, it could have occurred anywhere latitude-wise, in two longitude bands covering approximately half of Earth's surface, from India to Western Europe and from the Central USA to the Central Pacific Ocean.

Fragmentation refers to the fact that no collision could be identified. Still, objects below 10 cm are seldom tracked because of their small radar cross section and, if >1 cm, can still cause serious damage to spacecraft. They are also estimated to be more than half a million.

So it is entirely possible RISAT-1 was hit by such an "invisible" debris object and, while not obliterating it, the collision may have caused some pieces to break off due to the shock.

Alternatively, many satellites suffer debris-shedding malfunctions, meaning the liberated pieces have low relative speed with respect to the parent satellite. This could be a consequence of the collision not being energetic enough to boost large pieces off with high speeds, or just due to an internal event that breaks something (i.e. uncontained battery failure, leaks in the propulsion system, component overheat/overcool...). The fact that all debris shed from RISAT-1 in 2016 had a low ballistic coefficient (high area-to-mass ratio) and decayed quickly also hints at those pieces being insulation or the solar/SAR panels.
-DaviD-

Offline sanman

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Re: What Happened to RISAT-1?
« Reply #4 on: 04/10/2019 06:10 pm »
Thanks for the reply. So in the Tweet quoted in my OP, it says that 16 pieces were formed from the fragmentation event, out of which 15 decayed - but the 16th one apparently stayed in orbit and was catalogued on Oct 6, 2016. Could the initial orbit of this piece catalogued on Oct 6 help to further narrow down the location of where the fragmentation event originally occurred? (I guess we'd need to know more characteristics about the piece itself, such as its mass.)
« Last Edit: 04/10/2019 06:12 pm by sanman »

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #5 on: 04/11/2019 09:25 am »
Thanks for the reply. So in the Tweet quoted in my OP, it says that 16 pieces were formed from the fragmentation event, out of which 15 decayed - but the 16th one apparently stayed in orbit and was catalogued on Oct 6, 2016. Could the initial orbit of this piece catalogued on Oct 6 help to further narrow down the location of where the fragmentation event originally occurred? (I guess we'd need to know more characteristics about the piece itself, such as its mass.)

You mean something like propagate its orbit backwards and see when it intersected the original RISAT-1 orbit?

There will be too many uncertainties, starting with the orbits themselves, and the actual dV imparted during the fragmentation, which possibly account for the ▒2 hour sigma (~1 orbit). That piece was catalogued a week after it was shed, after quite a lot of orbit decay (and possibly tumbling reduction for a randomly-ejected piece), halfway through its decay process that culminated 5 days later. The fact that they manage to trace it back to its source with just that uncertainty is already quite remarkable.
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Offline sanman

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Re: What Happened to RISAT-1?
« Reply #6 on: 04/11/2019 11:51 am »
There's something else here - relating to RISAT-1's mission.

RISAT-1 was meant to do ground observation in all light conditions, including nighttime. Because of this, it was dubbed as having military/strategic utility:

http://www.indiandefencereview.com/news/risat-1-spy-satellite-launched/



On September 29, 2016  India carried out a cross-border military surgical strike operation against its neighbor following a terrorist attack. RISAT-1 may potentially have been involved in providing image data for this operation.

It was ~24 hours later that RISAT-1 was suddenly hit by the "fragmentation" event which rendered it inoperable. The probability of such coincidental timing of such an event seems rather astronomical, for a satellite which had already been in orbit uneventfully for 4.5 years. It naturally gives rise to suspicions of foul play.

https://idrw.org/did-loss-of-a-spy-satellite-pushed-india-to-develop-its-own-anti-satellite-missile-system/


Given India's recent ASAT test happening approximately 2 years after a decision was made to undertake it, I'm then wondering if that decision was made in response to the loss of RISAT-1. I'm wondering if RISAT-1 was itself the recipient of someone else's ASAT test, 2.5 years ago. There was no major debris cloud or other telltale signs, so I'm wondering if a more subtle ASAT weapon could have been used - ie. Directed Energy Weapon.

If unexplained losses of strategically important satellites occur with suspicious timings, then will there be a need for some kind of new science of "space forensics" (CSI: Orbital) to determine what actually happened, with some useful degree of confidence?
« Last Edit: 04/11/2019 12:20 pm by sanman »

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #7 on: 04/11/2019 12:29 pm »
[...]

Obviously this was the point of the OP all along, I was wondering how long it'd take until it was admitted :)

There's an article, easily accessible online, that brings up exactly the same points - baselessly except for the temporal coincidence.

I would say that:

1) this is firmly conspiracy theory territory, especially if you are suggesting third-country foul play of an unprecedented nature (in-orbit attack of foreign asset directly resulting in fragmentation and LOM, be it through Directed Energy Weapons or otherwise);
2) because of that, we're rapidly approaching topics (and more importantly, nationalistic angles) that were the cause of locking the ASAT test thread just two days before this thread was started - I'd call that temporal correlation.

On the technicalities:

3) the spacecraft had a design life specification of 5 years, and was launched 4.5 years before the fragmentation event, as you pointed out, i.e. the failure isn't especially premature;
4) there were many other skirmishes in the area that could be classified as "surgical" (i.e. limited military interventions in foreign-controlled territory) attacks in moments not correlating with damages to Indian space assets;
5) as I demonstrated upthread, the ground path of RISAT-1 in the time period the debris is thought to have been shed just barely includes Pakistan, and excludes China.

IMO, if it wasn't hit by a <10 cm piece of space debris, a far more reasonable explanation for why the fragmentation event happened soon after to the military operations of 2016 might be because it was with all certainty being extensively used during those events, making it more likely for a component (RCS?) to fail and cause loss of control after many years of operations, in the process breaking off some of the most fragile pieces (insulation, wide panels away from the CoM).
-DaviD-

Offline sanman

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Re: What Happened to RISAT-1?
« Reply #8 on: 04/11/2019 07:15 pm »

Obviously this was the point of the OP all along, I was wondering how long it'd take until it was admitted :)

:)

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There's an article, easily accessible online, that brings up exactly the same points - baselessly except for the temporal coincidence.

I assume it's the one I linked to near the end of my previous post.

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I would say that:

1) this is firmly conspiracy theory territory, especially if you are suggesting third-country foul play of an unprecedented nature (in-orbit attack of foreign asset directly resulting in fragmentation and LOM, be it through Directed Energy Weapons or otherwise);


When Falcon 9 blew up on the launch pad, there were all kinds of allegations, including the one about ULA shooting at it from their nearby rooftop. I recall SpaceX stating that they hadn't ruled it out, even as they made an appeal to the public for useful footage. I don't recall any immediate refutation of that as a conspiracy theory, howsoever far-fetched it may have sounded. When valuable hardware is lost, there can be an exhaustive search for answers.

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2) because of that, we're rapidly approaching topics (and more importantly, nationalistic angles) that were the cause of locking the ASAT test thread just two days before this thread was started - I'd call that temporal correlation.

I have an explanation for that temporal correlation:

In the previous thread, I'd speculated that the motive for India's ASAT test was due to a possible imminent global ASAT treaty. Since nobody else on the internet was saying the same, I'd looked around for other explanations and found this other one relating to RISAT-1, and thought it might be more relevant.

Howsoever far-fetched the ASAT explanation for the loss of RISAT-1 looks, its basis as a motivation for India's ASAT test may not be so far-fetched.


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On the technicalities:

3) the spacecraft had a design life specification of 5 years, and was launched 4.5 years before the fragmentation event, as you pointed out, i.e. the failure isn't especially premature;

Right down to the day after the surgical strike? That's a conspicuously precise failure timing relative to the previous 4.5 years.

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4) there were many other skirmishes in the area that could be classified as "surgical" (i.e. limited military interventions in foreign-controlled territory) attacks in moments not correlating with damages to Indian space assets;

To avoid threadlock, I don't wish to debate you in this area, other than to say you're wrong - it was a very noteworthy event of tremendous geopolitical significance.

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5) as I demonstrated upthread, the ground path of RISAT-1 in the time period the debris is thought to have been shed just barely includes Pakistan, and excludes China.

Could a space-based orbital weapon have been used? What are the possibilities?

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IMO, if it wasn't hit by a <10 cm piece of space debris, a far more reasonable explanation for why the fragmentation event happened soon after to the military operations of 2016 might be because it was with all certainty being extensively used during those events, making it more likely for a component (RCS?) to fail and cause loss of control after many years of operations, in the process breaking off some of the most fragile pieces (insulation, wide panels away from the CoM).

Yeah, I was thinking about that too. Are reaction wheels the most likely failure point? Even Kepler was salvaged after it's reaction wheel failure. Bear in mind that the fragmentation event occurred the day after after the military operation was carried out, and not before or during. The timing looks too suspicious to rule out an attack.

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #9 on: 04/11/2019 09:46 pm »
When Falcon 9 blew up on the launch pad, there were all kinds of allegations, including the one about ULA shooting at it from their nearby rooftop. I recall SpaceX stating that they hadn't ruled it out, even as they made an appeal to the public for useful footage. I don't recall any immediate refutation of that as a conspiracy theory, howsoever far-fetched it may have sounded. When valuable hardware is lost, there can be an exhaustive search for answers.

You may not recall, but I do: those baseless and often agenda-driven rumors were quickly denounced for what they were. Some of the earliest ones were allowed to remain in the interest of plurality but later ones moderated away, and its authors warned not to go down that path (I'm pretty sure some members even got suspended or banned at that time). This allowed NSF to remain free of vitriol, baseless speculations and badly-disguised agendas, in contrast to other corners of the web, full of those but devoid of reasonable analyses.

So far, the barely hidden agendas in this and the ASAT thread have been moderated just on the most shameless of cases, again in the interest of plurality - but the limits with nationalistic off-base speculation are again being skirted here.

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I have an explanation for that temporal correlation:
[...]

There is a reason the ASAT test was locked (twice, and unlocked once because of my intervention, since I find the topic extremely interesting - not the chest-thumping though, have enough of that elsewhere online and in the real world, so I'm not interceding again). The motivation is far-fetched because there is nothing to support it apart from the coincidence in time, which can point to other explanations, and tons evidence to at least cautiously reject it.

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Right down to the day after the surgical strike? That's a conspicuously precise failure timing relative to the previous 4.5 years.

That's what the last paragraph in my previous post was about.

Still, coincidences happen, and they are far more plausible than a) an unprecedented attack taking place on a sovereign nation's space assets that b) doesn't produce high-energy debris and just a few light pieces that reenter quickly, c) which India itself doesn't acknowledge, denounce or retaliate against in any way, d) motivated by a relatively quiet border skirmish.

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To avoid threadlock, I don't wish to debate you in this area, other than to say you're wrong - it was a very noteworthy event of tremendous geopolitical significance.

I agree the definition of the event and its significance are off-topic. Moreover, I do not claim to have much knowledge about the event, other than a faint recollection of hearing something in the news around that time. Not much on this side of the world, though.

For this reason, I attempted to gain a bit more insight in Wikipedia before writing though, and found https://en.wikipedia.org/wiki/India%E2%80%93Pakistan_border_skirmishes_(2016%E2%80%932018) , which lists dozens of skirmishes in the remainder of 2016, until a ceasefire proclaimed in mid-2018. Hardly few excuses for a hostile actor to continue ASATing, especially seeing the quiet reaction by Indian officials after the fragmentation of RISAT-1.

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Yeah, I was thinking about that too. Are reaction wheels the most likely failure point? Even Kepler was salvaged after it's reaction wheel failure. Bear in mind that the fragmentation event occurred the day after after the military operation was carried out, and not before or during. The timing looks too suspicious to rule out an attack.

I wasn't referring to reaction wheels, which probably couldn't break the sat's structure anyway (and why bring Kepler into this?!) - I'm talking about the hypergolic RCS. Frequently-used valves and plumbing provide an easy failure point, and leaks are not rare (see the quiet Intelsat 29e for a recent example).

The fact that it happened the day after the operations on the 29th doesn't mean anything - surely it was used extensively in the previous days, and as the Wiki article shows there were *lots* of daily skirmishes over the later few weeks, so there wasn't a lack of action for RISAT-1 to attempt to observe.
-DaviD-

Offline Lar

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Re: What Happened to RISAT-1?
« Reply #10 on: 04/11/2019 11:29 pm »
C'mon sanman, you know better... speculation on motives? Really?

This thread is about 1 post away from being locked.
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Offline sanman

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Re: What Happened to RISAT-1?
« Reply #11 on: 04/12/2019 01:02 am »
You may not recall, but I do: those baseless and often agenda-driven rumors were quickly denounced for what they were. Some of the earliest ones were allowed to remain in the interest of plurality but later ones moderated away, and its authors warned not to go down that path (I'm pretty sure some members even got suspended or banned at that time). This allowed NSF to remain free of vitriol, baseless speculations and badly-disguised agendas, in contrast to other corners of the web, full of those but devoid of reasonable analyses.

I wasn't talking about NSF per se - not all space-related statements happen on NSF - like I said, SpaceX themselves were quoted as not ruling out that theory initially, when asked about it.

https://www.washingtonpost.com/news/the-switch/wp/2018/02/26/after-2016-rocket-explosion-elon-musks-spacex-looked-seriously-at-sabotage/?utm_term=.817d1bdc3b04

When valuable assets are lost, all avenues of explanation may be pursued exhaustively.

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So far, the barely hidden agendas in this and the ASAT thread have been moderated just on the most shameless of cases, again in the interest of plurality - but the limits with nationalistic off-base speculation are again being skirted here.

Whether or not you feel there's a hidden agenda in myself or even some Walter Mitty - it's worth considering that whatever the reasons for the loss of RISAT-1, the follow-on consequences from that loss may have resulted in India's ASAT test.


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There is a reason the ASAT test was locked (twice, and unlocked once because of my intervention, since I find the topic extremely interesting - not the chest-thumping though, have enough of that elsewhere online and in the real world, so I'm not interceding again). The motivation is far-fetched because there is nothing to support it apart from the coincidence in time, which can point to other explanations, and tons evidence to at least cautiously reject it.

But that's the entire problem - the whole thing is shrouded in mystery - in space nobody can hear you scream. There were no direct witnesses to what happened to RISAT-1, other than the vague detection of the "fragmentation" event described in the OP. So that's why I find the forensic examination of this case to be interesting. Otherwise, "invisible sub-10cm orbital debris" can become the cheap and lazy explanation for anything and everything - the "cop-out". (Did BFR explode on its maiden re-entry? Just blame "invisible sub-10cm orbital debris"  :P)

What is this other evidence that rejects the possibility of anything other than misfortune?

My purpose in this thread was not to engage in chest-thumping - I don't see an example of it so far in this thread - it was rather because I too find it interesting to examine the mystery of what happened to RISAT-1.

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That's what the last paragraph in my previous post was about.

You stated that the satellite was approaching the end of its design life - but the issue is about the loss of the satellite on a particular day, not which year or decade it went dead. It's rather Bayesian.


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Still, coincidences happen, and they are far more plausible than a) an unprecedented attack taking place on a sovereign nation's space assets that b) doesn't produce high-energy debris and just a few light pieces that reenter quickly, c) which India itself doesn't acknowledge, denounce or retaliate against in any way, d) motivated by a relatively quiet border skirmish.

Responses to the above:
a)   https://spacenews.com/nro-confirms-chinese-laser-test-illuminated-us-spacecraft/
b)   what kind of debris should we necessarily expect from such a scenario?
c)    https://forum.nasaspaceflight.com/index.php?topic=47757.0
d)   The event was heavily covered in Indian news media, and was not some small incident, just like the raid on Bin Laden was not some small incident in US news coverage. Let's not debate the significance.


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I agree the definition of the event and its significance are off-topic. Moreover, I do not claim to have much knowledge about the event, other than a faint recollection of hearing something in the news around that time. Not much on this side of the world, though.

Then let's avoid discussing that preceding event itself and focus on what could have caused the satellite to be lost the very next day after that event.


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For this reason, I attempted to gain a bit more insight in Wikipedia before writing though, and found https://en.wikipedia.org/wiki/India%E2%80%93Pakistan_border_skirmishes_(2016%E2%80%932018) , which lists dozens of skirmishes in the remainder of 2016, until a ceasefire proclaimed in mid-2018. Hardly few excuses for a hostile actor to continue ASATing, especially seeing the quiet reaction by Indian officials after the fragmentation of RISAT-1.

Actually, in the 6th post of the thread I'd provided a much better link with more detailed information:
https://en.wikipedia.org/wiki/2016_Indian_Line_of_Control_strike

My point here is not to dwell on that event, but to look at how the satellite could have gone dead in such close time proximity to that event.

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I wasn't referring to reaction wheels, which probably couldn't break the sat's structure anyway (and why bring Kepler into this?!) - I'm talking about the hypergolic RCS. Frequently-used valves and plumbing provide an easy failure point, and leaks are not rare (see the quiet Intelsat 29e for a recent example).

Sorry, I should have understood it as Reaction Control System thrusters, but for some reason I thought of the reaction wheels. Okay, so RCS thrusters tend to alter the orbit of the spacecraft, don't they? Was any evidence of a change in the spacecraft's orbit observed prior to the detection of the fragmentation event?

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The fact that it happened the day after the operations on the 29th doesn't mean anything - surely it was used extensively in the previous days, and as the Wiki article shows there were *lots* of daily skirmishes over the later few weeks, so there wasn't a lack of action for RISAT-1 to attempt to observe.

Again, I 'd like to avoid diverting into the topic of the relative importance of the Sep-29 raid compared to other skirmishes, since this digresses away from space-related content. It's like saying that the raid on the Bin Laden compound had no special significance compared to other skirmishes that day between the US military and the Pakistani military on the Pak-Afghan border. Since we're not here to have thorny debates on the relative significance of particular military ground operations, then let's avoid debating the importance of that event and not take issue against it. Maybe we're into Bayes territory here.

C'mon sanman, you know better... speculation on motives? Really?

This thread is about 1 post away from being locked.


The facts we do have to go on include that the fragmentation of the spacecraft generated 16 pieces, out of which 15 de-orbited and the 16th stayed in orbit. Is it at least uncontroversial to assume that all 16 of those pieces were from RISAT-1 itself?

Since ISRO tends to re-use existing hardware designs, is there any past history of those hypergolics failing in orbit?


One more thing...
Is there any hardware in use that can detect sub-10cm orbital debris?

« Last Edit: 04/12/2019 03:08 am by sanman »

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #12 on: 04/12/2019 08:45 am »
I *really* don't understand the obtuseness, and the apparent lack of background checks, on what you're suggesting or asking about, for an event that you claim to be so interested on. By the way, since it appears I have to spell it out: obviously we're talking about the attitude of NSF towards baseless rumors, not of other sites, because I'm explaining the moderation rationale here, not in spacestuffgoesboom.com. Let's focus.

As I said, this is getting into conspiracy theory territory because, in spite of mounting evidence that I've been presenting to you (all of it fairly easy to find or deduce for an interested armchair spectator by the way, I don't have specific knowledge), you keep moving the goalposts to try to prove a negative, i.e. that it was NOT hit by untrackable debris or suffered an internal failure, so the valid explanation must be the baseless idea of an unlikely ASAT.

At the end of the day, the best reason why this failure wasn't an ASAT is that the Indian officials didn't try to capitalize *at all* on what would be an unprecedented situation that would result in an easy worldwide condemnation of the attack (the "illumination" or blinding of sensitive satellites from the ground you refer to in your link about China/US has been "common" since at least the 80s, but it at most results on a temporary impairment, not on physical damage or LOM), especially during an active military operation that would drag on for 2 years and the first episode of which was perceived in India as a game-changer, according to your perspective. Not only that, but officials refused to acknowledge for months even that the satellite had an anomaly! By the way, it appears RISAT-2 is still operational, why would an attacking power stop at disabling just one radar imaging satellite?

Again: the satellite failing on the particular day just after the start of military operations, and about a week after the triggering event, makes sense from the internal failure point of view, because it would have been required to perform frequent RCS operations, perhaps more demanding than nominal, when it was already approaching the end of its design life. Of course, many other failure modes could have been possible but hard to determine from the ground without telemetry insight, without resorting to a <10 cm debris impact, which remains nevertheless a valid possibility.

Note RCS not only "tends" to change the orbit, but also the satellite's attitude (and desaturate the reaction wheels), which is required for imaging in most of RISAT-1's modes! In this case, it had 8 thrusters for attitude control and a single identical one for orbital maneuvers.

The 16 pieces were the trackable ones, probably there were dozens of others, and it appears they are pretty confident they all came from RISAT-1. The 10 cm size threshold is not a hard one, simply a function of radar reflectivity of the object, its variability (tumbling) and orbital lifetime. In fact, new generation optical telescopes in space and on the ground are aiming to reduce that threshold (mainly down to ~2-5 cm) but they still can't offer a service like NORAD's public individual TLEs, and are probably more focused on getting the population distributions right.
-DaviD-

Offline sanman

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Re: What Happened to RISAT-1?
« Reply #13 on: 04/12/2019 10:35 pm »
I *really* don't understand the obtuseness, and the apparent lack of background checks, on what you're suggesting or asking about, for an event that you claim to be so interested on. By the way, since it appears I have to spell it out: obviously we're talking about the attitude of NSF towards baseless rumors, not of other sites, because I'm explaining the moderation rationale here, not in spacestuffgoesboom.com. Let's focus.

No worries - I was being focused when I brought up the example of SpaceX not immediately ruling out sabotage for the pad explosion of Falcon9. I was simply making the point that owners of valuable assets (eg. launch vehicles, satellites) can engage in an exhaustive search for answers, even looking at controversial possibilities when no obvious clues are immediately available. That had nothing to do with any commentary on NSF's policies, I was simply pointing out the early reaction of SpaceX themselves to show that such responses aren't automatically fringe paranoia.


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As I said, this is getting into conspiracy theory territory because, in spite of mounting evidence that I've been presenting to you (all of it fairly easy to find or deduce for an interested armchair spectator by the way, I don't have specific knowledge), you keep moving the goalposts to try to prove a negative, i.e. that it was NOT hit by untrackable debris or suffered an internal failure, so the valid explanation must be the baseless idea of an unlikely ASAT.

Mounting evidence? Of invisible, untrackable sub-10cm debris which show up at odd moments? If you and others are making the positive assertion on debris that are by definition invisible and untrackable, then shouldn't you be trying to supply proof of this specific cause of LOM? Otherwise it seems that invisible, untrackable sub-10cm debris become a convenient fallback, like the "ghost in the machine". Invisible, untrackable debris become "orbital gremlins".


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At the end of the day, the best reason why this failure wasn't an ASAT is that the Indian officials didn't try to capitalize *at all* on what would be an unprecedented situation that would result in an easy worldwide condemnation of the attack (the "illumination" or blinding of sensitive satellites from the ground you refer to in your link about China/US has been "common" since at least the 80s, but it at most results on a temporary impairment, not on physical damage or LOM), especially during an active military operation that would drag on for 2 years and the first episode of which was perceived in India as a game-changer, according to your perspective. Not only that, but officials refused to acknowledge for months even that the satellite had an anomaly! By the way, it appears RISAT-2 is still operational, why would an attacking power stop at disabling just one radar imaging satellite?

But here we're specifically talking about a "fragmentation" event, and not a mere illumination blinding. At the time of the fragmentation event, there was no active military operation going on, since the latter was a brief cross-border raid which had been carried out ~24 hours earlier. But let's not talk about that cross-border strike or whether it would have been sufficient motive to take out the satellite which would likely have been used for it. Let's instead talk about what evidence might be looked at to help draw a conclusion on what happened to the satellite afterwards.

As to why RISAT-2 wouldn't have been similarly disabled in an attack, one explanation might be that this would have been a very telltale sign that an orchestrated attack had occurred. If you wanted to attack a satellite, then wouldn't it be best to leave it untraceable so that nobody knows what you did?

In which case, Indian officials may not have immediately understood that an attack had occurred, but later concluded that there was a sufficient possibility to warrant ordering an ASAT test, which then took ~2 years to prepare. The ordering of a test demonstration of ASAT capability could be interpreted as consistent with a response to a perceived ASAT attack.

Also, since RISAT-2 was originally Israeli-manufactured TecSAR2, acquired and launched by India, I'm unsure whether it might not be under some kind of joint usage by both countries, a political complication which could potentially deter attack against it.
Just like Kuwaiti tanker vessels operating under the US flag in the Persian Gulf, is there a possibility that surveillance satellites could be time-shared and operated under multiple flags, to enjoy the perception of protection by said multiple countries?



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Again: the satellite failing on the particular day just after the start of military operations, and about a week after the triggering event, makes sense from the internal failure point of view, because it would have been required to perform frequent RCS operations, perhaps more demanding than nominal, when it was already approaching the end of its design life. Of course, many other failure modes could have been possible but hard to determine from the ground without telemetry insight, without resorting to a <10 cm debris impact, which remains nevertheless a valid possibility.

Note RCS not only "tends" to change the orbit, but also the satellite's attitude (and desaturate the reaction wheels), which is required for imaging in most of RISAT-1's modes! In this case, it had 8 thrusters for attitude control and a single identical one for orbital maneuvers.

Okay, so internal hardware failure is a more interesting possibility, since its usage could have more likely corresponded with the military raid whose timing was close to the fragmentation event. The satellite would have been used ahead of the actual military raid, and likely afterwards as well to verify and assess the effects of the military raid. Use of certain hardware on the satellite (eg. RCS) could augment the risk to it. So assuming the fragmentation event would've been more likely to happen during actual usage of the RCS, and given the orbit of the satellite (revisitation cycle time of the satellite being ~12 days), would RCS have likely been used at around the time that the fragmentation event occurred?

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The 16 pieces were the trackable ones, probably there were dozens of others, and it appears they are pretty confident they all came from RISAT-1. The 10 cm size threshold is not a hard one, simply a function of radar reflectivity of the object, its variability (tumbling) and orbital lifetime. In fact, new generation optical telescopes in space and on the ground are aiming to reduce that threshold (mainly down to ~2-5 cm) but they still can't offer a service like NORAD's public individual TLEs, and are probably more focused on getting the population distributions right.

Good to know. So at least there's a chance of more invisible gremlins being catalogued and pinned down, rather than continuing to roam around invisibly, being attributable for everything.

I think that as more expensive objects continue to be put in space, and lost too, then there's going to naturally be a growing desire to know exactly how/why something was lost. Insurance companies are going to want to know, as it all affects their bottom line.

There's going to have to be some emerging forensic science for this stuff, in order to attribute liability if/when applicable.
« Last Edit: 04/12/2019 11:03 pm by sanman »

Offline Kansan52

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Re: What Happened to RISAT-1?
« Reply #14 on: 04/12/2019 11:21 pm »
"What is this other evidence that rejects the possibility of anything other than misfortune?"

Occam's Razor.

Offline sanman

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Re: What Happened to RISAT-1?
« Reply #15 on: 04/12/2019 11:40 pm »
"What is this other evidence that rejects the possibility of anything other than misfortune?"

Occam's Razor.

I don't agree with your use of Occam's Razor here - otherwise by that logic, then every airliner crash was automatically due to wind shear.

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #16 on: 04/13/2019 10:00 am »
Mounting evidence? Of invisible, untrackable sub-10cm debris which show up at odd moments? [...]

No, mounting evidence of an ASAT being improbable because of factors (groundtrack, shedding pattern, context...) that discredit this theory so many other plausible failure modes, including but not limited to the sub-decimeter debris. Please reread upthread if you missed those, they are the main content of my posts.

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But here we're specifically talking about a "fragmentation" event, and not a mere illumination blinding. [...] In which case, Indian officials may not have immediately understood that an attack had occurred, but later concluded that there was a sufficient possibility to warrant ordering an ASAT test, which then took ~2 years to prepare.[...]

Let me get this right: you're discrediting the possibility of untrackable orbital debris being the cause for this failure as "orbital gremlins", when they're a proven, large orbital debris population with unknown precise TLEs, making up the majority of dangerous material in orbit --

but

then you argue for an unprecedented, never-seen-before major military operation physically destroying and signifying LOM for a critical sovereign nation's asset being performed by an unknown actor for unknown precise reasons, even being unbeknownst to India's top officials for a long time? That reasoning doesn't hold up very well.

BTW, we obviously don't have access to it, but surely those Indian officials have all available telemetry at their disposal and they surely know with quite a high degree of certainty what happened to RISAT-1. As I said, the fact they did not capitalize on a purported ASAT, which would invariably mean an immediate gain of support for their cause even if discovered some time later, already shows that possibility to be a non-starter as an explanation for the fragmentation.

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[...]would RCS have likely been used at around the time that the fragmentation event occurred?

As I showed upthread, the ground path around the time of fragmentation would have taken it over India/Pakistan a few hours before the central time estimate for the event.

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There's going to have to be some emerging forensic science for this stuff, in order to attribute liability if/when applicable.

Forensics are fine with evidence, otherwise it's just speculation.

The use of Occam's razor that Kansan52 proposes is not "any failure cause = the most probable cause" but instead "failure cause = the simplest cause when taking into account all available evidence", which in this case all points away from an ASAT -- even the timing, which can be attributed to simpler, more reasonable events.
-DaviD-

Offline sanman

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Re: What Happened to RISAT-1?
« Reply #17 on: 04/14/2019 04:25 am »
No, mounting evidence of an ASAT being improbable because of factors (groundtrack, shedding pattern, context...) that discredit this theory so many other plausible failure modes, including but not limited to the sub-decimeter debris. Please reread upthread if you missed those, they are the main content of my posts.

Let me get this right: you're discrediting the possibility of untrackable orbital debris being the cause for this failure as "orbital gremlins", when they're a proven, large orbital debris population with unknown precise TLEs, making up the majority of dangerous material in orbit --

Not arguing their existence, I'm saying that their attribution is a speculative fallback with all too convenient timing. Why didn't the sub-decimeter debris disable the satellite during the previous 4.5 years? Do sub-decimeter debris care about design life?
 
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but

then you argue for an unprecedented, never-seen-before major military operation physically destroying and signifying LOM for a critical sovereign nation's asset being performed by an unknown actor for unknown precise reasons, even being unbeknownst to India's top officials for a long time? That reasoning doesn't hold up very well.

Well, as I linked to before, US NRO satellites have been illuminated by lasers since over a decade earlier - the only difference here would be the degree of power or intensity. So why would the ASAT scenario amount to something major and unprecedented? Human beings are much more precise and discriminating agents of destruction than sub-decimeter orbital debris.

"Assumptions should be based on capabilities, not intentions" - old military aphorism.


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BTW, we obviously don't have access to it, but surely those Indian officials have all available telemetry at their disposal and they surely know with quite a high degree of certainty what happened to RISAT-1. As I said, the fact they did not capitalize on a purported ASAT, which would invariably mean an immediate gain of support for their cause even if discovered some time later, already shows that possibility to be a non-starter as an explanation for the fragmentation.

How would they be able to capitalize up front on an ASAT incident without any telltale evidence? If there were a debris cloud or some other evidence pointing to a kinetic kill vehicle, that would be something else. But if it were directed energy - then what means exists to discern telltale evidence of this?



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As I showed upthread, the ground path around the time of fragmentation would have taken it over India/Pakistan a few hours before the central time estimate for the event.

So that's no evidence that RCS was used, which was what I was looking for. The point being that usage of risk-augmenting hardware like RCS could then correlate to a hardware failure that disabled the satellite.

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Forensics are fine with evidence, otherwise it's just speculation.

Which is the point of forensics - to discern and examine evidence more closely. The ability to examine the pieces of a disabled/destroyed satellite could be a vitally useful capability in the future.

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The use of Occam's razor that Kansan52 proposes is not "any failure cause = the most probable cause" but instead "failure cause = the simplest cause when taking into account all available evidence", which in this case all points away from an ASAT -- even the timing, which can be attributed to simpler, more reasonable events.

The simplest cause can be The Heat Death of the Universe - but if the timing of the simplest cause looks improbable then it's going to be questionable.
« Last Edit: 04/14/2019 05:11 am by sanman »

Offline eeergo

Re: What Happened to RISAT-1?
« Reply #18 on: 04/15/2019 09:19 am »
Are we going in circles here? Or just willfully tuning up a notch the obtuseness?

I put forward two hypothesis for the fragmentation, more likely than an unprecedented ASAT weapon attack that doesn't leave high-energy debris and is not directly responded upon or claimed by even the attacked satellite's owners.

1- Internal failure --which can include, but is not limited to, the RCS system, but also the batteries or any other energy storage system inside the satellite. This hypothesis is supported by:
i) General timing of the event (in the days just after, before and during military operations around 2016.10.29)
ii) Particular timing of the event (ground path appears to have gone over India/Pakistan in the -1sigma limit from the median calculated time of the fragmentation, which could mean satellite heavy use a few minutes/hours before the event).
iii) Design life of satellite (passed 90% of design life, probable high-intensity use of RCS for imaging during critical military period). As I said before, you ignored, and I'll repeat for the last time, you need RCS for imaging: if not directly, at least to desaturate the wheels after they allowed the craft to slew.
iv) Visible debris shed was a few pieces with low-energy and high area-to-mass ratio (large, flimsy components which can detach if subjected to past-design-limits forces but would be flying off with large velocities if a weapon hit them).
v) Lots of satellites fail in such a way: see Intelsat 29e recently, but also Hitomi tearing itself apart, etc.
vi) Refusal by owners to acknowledge loss of control happened, just pointing to a "recoverable anomaly" in the moths after the event. Later quietly listed as lost when position was no longer defensible.

2- Untrackable dangerous debris (sub-decimeter). This hypothesis is supported by:
i) >0.5M objects estimated to populate Earth orbits, most of them in MEO/LEO regimes.
ii) Debris won't fully penetrate most spacecraft, causing internal damage but not large-scale destruction, and not transferring a whole lot of momentum (=low energy resulting debris).
iii) Most logical reaction to such an event will be confusion and trying to minimize damage until end result is clear, as happened in 2016-17.
iv) Polar orbit would leave RISAT-1 exposed to debris from all orbits passing through its altitude range, most with a large relative velocity.

3- By contrast, the directed-energy ASAT hypothesis, while being a type of weapon that was never used as a destructive force in space before (only as a "blinding" agent, and somewhat inconclusively since it can be easily claimed a ranging high-power laser is trying to blind a spacecraft though high-power directed energy, or viceversa), is supported by:
i) Timing of the event (but not really, since the ground path during the credible interval of the event didn't take RISAT-1 over China, who appears to be the main suspect for such an attack and wouldn't risk exporting/operating such novel equipment abroad for fear of leaks, and consequently being spotlighted).
ii) Low energy debris (but not really either, since capability to fragment a satellite with a high-energy-density beam hasn't been documented or suspected before by any nation, and if it was really that powerful to break components free it would probably have made the satellite's fuel tanks blow up, creating a much larger and energetic debris field).
iii) ...baseless paranoid forensics are needed because there's such a well-disguised conspiracy against a single asset (which noewadays even several private companies possess) that an accident or an internal failure must be disregarded as na´ve?

Of course, from the list above the very sizable advantage of hypothesis 3 is missing: iv) somewhat justifying the deeply misguided and irresponsible missile-based ASAT test of 2019 as an answer to a previous attack, which most nationalist war-mongers are yearning for. And that's the only real purpose of this thread, since the dedicated one got locked by virtue of several persistent peaceful-minded and well-founded posts.
-DaviD-

Online notsorandom

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Re: What Happened to RISAT-1?
« Reply #19 on: 04/15/2019 06:23 pm »
The timing of the two events, the military operation and the loss of RISAT-1, makes me think they were unrelated. I don't think there was enough time between them for an ASAT operation to take place.

1. It took time for Pakistan and the rest of the world to confirm that a strike really did happen. If anyone wished to take action against an India for it they would need to confirm that an incident really did take place beyond just trusting what the Indian military stated.

2. To strike the satellite as a retaliation one would have to know it was involved in the military operation. Otherwise it would be a blindly aggressive and unmeasured act. One may have suspicions that RISAT-1 was being used for military purposes. However baring an extremely trustworthy source, a day is unlikely to be enough time to vet the intelligence indicating that the satellite was used in the strike.

3. A country with the military capability to take out a satellite likely has a large governmental and military bureaucracy. An action like this would require a decision at the very top levels of government. It would take time for a decision to be passed up and then back down the chain of command.

4. An ASAT weapon would need time gain good targeting information and be deployed in the right time and place.

There are certainly ways around those points but it would require both a lot of pre-planning and taking on quite a bit of risk that the satellite might not have been involved or even that there wasn't a strike in the first place. Waiting another day or two would have given more time to resolve those issues and still would have sent the same message of retaliation. Without any further knowledge I don't think there was enough time for a hostile actor to attack the satellite.

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