Author Topic: 3 recent Centaur debris shedding events.  (Read 10035 times)

Offline DatUser14

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3 recent Centaur debris shedding events.
« on: 04/25/2019 04:13 pm »
With the news of AEHF-4's centaur shedding debris reported today:

https://twitter.com/18SPCS/status/1121184362559496192

I am also reminded of two recent centaurs debris shedding

Nemesis 1 April 12 2019:

https://twitter.com/ElecnorDeimos/status/1116639114965782528

Nemesis 2 Aug 30th 2018:

http://iaaweb.org/iaa/Scientific%20Activity/debrisminutes09184.pdf

Three in a year of the same kind of stage is a trend. What's going on here?
« Last Edit: 04/25/2019 05:32 pm by DatUser14 »
Titan IVB was a cool rocket

Offline intelati

Re: Recent Centaur debris shedding.
« Reply #1 on: 04/25/2019 04:19 pm »
This is a little freaky. haha. I just started to do some research myself to get a lay of the land.

Followed some interesting, but unrelated trails.

I guess at a certain point, a thin walled stage (Covered by the 5m fairing) could get hit by micro-debris and explode, but really I have no experience with that. I'm at a loss as well for the "trend" of disintegrating stages
Starships are meant to fly

Offline edkyle99

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Re: Recent Centaur debris shedding.
« Reply #2 on: 04/25/2019 05:28 pm »
Centaurs have helium pressurization for both the primary propellant tanks and for the hydrazine RCS system.  The stages also have batteries.  The propellant systems are supposed to be safed (pressurant blow-down) at the end of the mission.  The hydrazine is a monopropellant.  Batteries are harder to "safe", I think, and have been responsible for a number of satellite break-ups recently.

 - Ed Kyle

Offline Jim

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Re: 3 recent Centaur debris shedding events.
« Reply #3 on: 04/25/2019 06:06 pm »
This is a little freaky. haha. I just started to do some research myself to get a lay of the land.

Followed some interesting, but unrelated trails.

I guess at a certain point, a thin walled stage (Covered by the 5m fairing) could get hit by micro-debris and explode, but really I have no experience with that. I'm at a loss as well for the "trend" of disintegrating stages

The fairing was jettisoned. the stages are exposed

Offline intelati

Re: 3 recent Centaur debris shedding events.
« Reply #4 on: 04/25/2019 06:13 pm »
I guess at a certain point, a thin walled stage (Covered by the 5m fairing) could get hit by micro-debris and explode, but really I have no experience with that. I'm at a loss as well for the "trend" of disintegrating stages

The fairing was jettisoned. the stages are exposed

Ahh. I wasn't clear (covered by the 5m fairing for launch.)
Starships are meant to fly

Offline Patchouli

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Re: 3 recent Centaur debris shedding events.
« Reply #5 on: 04/26/2019 12:12 am »
Centaurs have helium pressurization for both the primary propellant tanks and for the hydrazine RCS system.  The stages also have batteries.  The propellant systems are supposed to be safed (pressurant blow-down) at the end of the mission.  The hydrazine is a monopropellant.  Batteries are harder to "safe", I think, and have been responsible for a number of satellite break-ups recently.

 - Ed Kyle
Don't satellites typically use nickle hydrogen batteries which operate under high pressure while rocket stages typically use silver zinc or lithium ion batteries?
« Last Edit: 04/26/2019 12:14 am by Patchouli »

Offline edkyle99

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Re: 3 recent Centaur debris shedding events.
« Reply #6 on: 04/26/2019 03:12 am »
Centaurs have helium pressurization for both the primary propellant tanks and for the hydrazine RCS system.  The stages also have batteries.  The propellant systems are supposed to be safed (pressurant blow-down) at the end of the mission.  The hydrazine is a monopropellant.  Batteries are harder to "safe", I think, and have been responsible for a number of satellite break-ups recently.

 - Ed Kyle
Don't satellites typically use nickle hydrogen batteries which operate under high pressure while rocket stages typically use silver zinc or lithium ion batteries?

I'm not sure which type Centaur uses.  I do know that many battery types can rupture under certain conditions.  They are little chemistry sets, filled with acids and other stuff that can promote "plate growth" (crystal growth) and other chemically things (I'm an EE).  Their containers, which probably include pressure relief valves, are going to be degraded over time out in space, letting the fun out of the bag maybe.  (I do failure testing.  Lithium ion batteries have provided me with all sorts of fun, recently.)  If the Centaur issue is not propellant related (and it shouldn't due to the blow-downs) than the next thing to suspect should be batteries.  There could be other reasons, of course.

 - Ed Kyle   
« Last Edit: 04/26/2019 03:14 am by edkyle99 »

Offline MATTBLAK

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Re: 3 recent Centaur debris shedding events.
« Reply #7 on: 04/26/2019 05:03 am »
Can anyone tell me what type of battery sets the Dragon 2 spacecraft uses?
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Offline Steven Pietrobon

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Re: 3 recent Centaur debris shedding events.
« Reply #8 on: 04/26/2019 06:52 am »
Can anyone tell me what type of battery sets the Dragon 2 spacecraft uses?

99.99% sure its Lithium Ion.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline RotoSequence

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Re: Recent Centaur debris shedding.
« Reply #9 on: 04/26/2019 08:31 am »
Centaurs have helium pressurization for both the primary propellant tanks and for the hydrazine RCS system.  The stages also have batteries.  The propellant systems are supposed to be safed (pressurant blow-down) at the end of the mission.  The hydrazine is a monopropellant.  Batteries are harder to "safe", I think, and have been responsible for a number of satellite break-ups recently.

 - Ed Kyle

So many, with asynchronous launch dates, coming apart in close proximity with no apparent cause?

Spy thriller cliche, sure, but Ian Fleming's quote feels hard to ignore: “Once is happenstance. Twice is coincidence. Three times is enemy action.”
« Last Edit: 04/26/2019 09:06 am by RotoSequence »

Offline edkyle99

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Re: 3 recent Centaur debris shedding events.
« Reply #10 on: 04/26/2019 01:19 pm »
Centaurs have helium pressurization for both the primary propellant tanks and for the hydrazine RCS system.  The stages also have batteries.  The propellant systems are supposed to be safed (pressurant blow-down) at the end of the mission.  The hydrazine is a monopropellant.  Batteries are harder to "safe", I think, and have been responsible for a number of satellite break-ups recently.

 - Ed Kyle

So many, with asynchronous launch dates, coming apart in close proximity with no apparent cause?

Spy thriller cliche, sure, but Ian Fleming's quote feels hard to ignore: “Once is happenstance. Twice is coincidence. Three times is enemy action.”
There's no reason to destroy three derelict upper stages.  Upper stage explosions have happened since the early space age.  Dozens of them have probably exploded over the years.  Delta upper stages were the worst offenders for many years.  Something like 200 or so upper stages and satellites have exploded or "shed debris" over the years.

 - Ed Kyle


Offline eeergo

Re: 3 recent Centaur debris shedding events.
« Reply #11 on: 04/26/2019 02:17 pm »
Tory Bruno appears to point away from fragmentations being due to internal events, but of course what else would he say.

https://twitter.com/torybruno/status/1121741888204070915

Offline LouScheffer

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Re: 3 recent Centaur debris shedding events.
« Reply #12 on: 05/02/2019 06:11 pm »
Something systematic seems to be going on.  All stages were in high perigee GTO orbits:

2009-047B  6675 km x 34700 km, 23o
2014-055B  8202 km x 35180 km, 22o
2018-079B  8914 km x 35800 km, 12o

They all broke up into lots of big pieces, implying a fair amount of energy.  Tony Bruno's comments notwithstanding, it seems like there must still be some stored energy somewhere.

My personal guess would be the hydrazine system.  The big tanks have pressure relief values, I think.  It's hard for me to see how a battery exploding could make lots of large pieces.  Hydrazine, though, has lots of potential energy.  The stage starts with 150 kg of hydrazine.  If some portion was not vented but was instead trapped, it could decompose, raising pressure until something explodes. This could account for the several year time scale as well as the fairly high energy.

Maybe ULA should re-visit the safing procedures designed by that summer intern?  Just joking, but perhaps the safing procedures did not get the same level of analysis as the portions needed for mission success.

If analysis does not reveal the problem. and it still needs to be diagnosed, you could imagine a small low-rate telemetry package, run by solar cells with no battery (so it does not add to the problem).  This would only send data while the stage is in sunlight, but would likely be enough to figure out what's going on.

EDIT: fix markup for superscript degrees

« Last Edit: 05/02/2019 06:50 pm by LouScheffer »

Offline envy887

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Re: 3 recent Centaur debris shedding events.
« Reply #13 on: 05/02/2019 08:21 pm »
Isn't the USAF requiring a disposal burn for these missions now?

Online ZachS09

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Re: 3 recent Centaur debris shedding events.
« Reply #14 on: 05/02/2019 09:42 pm »
Isn't the USAF requiring a disposal burn for these missions now?

They did do deorbit burns for the recent WGS missions on Delta IV as well as SBIRS-GEO 4 on Atlas V.
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Offline LouScheffer

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Re: 3 recent Centaur debris shedding events.
« Reply #15 on: 05/05/2019 11:18 pm »
[...]  Upper stage explosions have happened since the early space age.  Dozens of them have probably exploded over the years. 

Ed, should not these count on your scorecard as launch vehicle failures?  They released the payloads into the desired orbits, and then they had the secondary mission goal of not exploding (at least the vehicles like Centaur, that take explicit steps to passivate the stage.)  So if this procedure does not work, and the rocket stage breaks up, that's a failure to achieve a pre-acknowledged mission goal to which they had explicitly agreed.  That's a failure.
« Last Edit: 05/05/2019 11:19 pm by LouScheffer »

Online gongora

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Re: 3 recent Centaur debris shedding events.
« Reply #16 on: 05/05/2019 11:29 pm »
Isn't the USAF requiring a disposal burn for these missions now?

They don't require deorbit burns if something is delivered to a high perigee orbit.

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Re: 3 recent Centaur debris shedding events.
« Reply #17 on: 05/06/2019 03:47 pm »
ODMSP document can be seen at:
https://orbitaldebris.jsc.nasa.gov/library/usg_od_standard_practices.pdf

Accepted disposal strategies for upper stages include:
- reentry within 25 years
- storage orbit between 2000km and 19700km
- storage orbit between 20700km and 35300km
- storage orbit above 36100km

Someone suggested to me that certain programs might have been launching under waivers from the ODMSP requirements but NSSL launches are supposed to get a lot better about that in the future.  It's not clear what rules other government launches intend to follow (the last GOES launch didn't comply with ODMSP).  By far the most common way in which launches don't comply with the ODMSP requirements is by leaving upper stages in orbits that cross the area in MEO between 19700 and 20700km.

I tried figuring out a quick space-track query that would show stages of interest.  This doesn't give an exact list of the non-complying stages but it got me in the ballpark: (requires space-track.org account)
Query launches from AFETR with apogree > 20700, perigee > 1000, object = "rocket body"

Just eyeballing the list, it looks to me like there are 26 upper stages launched from AFETR since 2010 that are currently in orbits that cross through the region between 19700 and 20700.  One of those also goes above 35300km.  These include the upper stages from some of the GPS launches.

Offline LouScheffer

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Re: 3 recent Centaur debris shedding events.
« Reply #18 on: 05/06/2019 06:26 pm »
Someone suggested to me that certain programs might have been launching under waivers from the ODMSP requirements but NSSL launches are supposed to get a lot better about that in the future. 
It's easy to imagine they got a waiver for their particular disposal orbit.  Anything else would be expensive in terms of delta-V.

However, I see no reason they should get a waiver for requirement 4.4-1, (required by both DOD's SPACE SAFETY AND MISHAP PREVENTION PROGRAM : AIR FORCE INSTRUCTION 91-217 and NASA's Process for Limiting Orbital Debris ) which both require a less than 0.001 chance of exploding on orbit:
Quote
Requirement 4.4-1: Limiting the risk to other space systems from accidental explosions during deployment and mission operations while in orbit about Earth or the Moon: For each spacecraft and launch vehicle orbital stage employed for a mission (i.e., every individual free-flying structural object), the program or project shall demonstrate, via failure mode and effects analyses, probabilistic risk assessments, or other appropriate analyses, that the integrated probability of explosion for all credible failure modes of each spacecraft and launch vehicle does not exceed 0.001 (excluding small particle impacts.).
With overwhelming probability, this has been violated, with 3 centaur breakups from about 60 Atlas-5 GTO missions, a 5% failure rate.  (The odds of observing 3 breakups in 60 measurements, assuming each had a 0.001 chance, is about 3x10-5.)

So I'd think they either need to get a waiver for this, or present an analysis that shows why their prior procedures did not work, and how they have remedied it.

Offline LouScheffer

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Re: 3 recent Centaur debris shedding events.
« Reply #19 on: 05/14/2019 07:08 pm »
Something systematic seems to be going on.  All stages [that broke up] were in high perigee GTO orbits:

2009-047B  6675 km x 34700 km, 23o
2014-055B  8202 km x 35180 km, 22o
2018-079B  8914 km x 35800 km, 12o
Although there are about 42 Atlas-5 Centaur stages left in earth orbit, the three that broke up were part of a small group of high-perigee GTO orbits.  The other two similar orbits I could find are

Intelsat-14   6157 km x 39094 km, 22.5o
GOES-16    8108 km x 35286 km, 10.6o

The 5 MUOS second stages have perigees about 3800 km, the three TDRS about 4700 km, and the GPS second stages are circular at about 21000 km.   Most of the rest are in traditional low (few hundred km perigee) GTO orbits but have not decayed yet, or super-GEO orbits from direct-to-GEO missions.

Given that three out of five with high perigee GTO orbits have broken up, and none of any other groups, I'm going to predict that GOES-16 or Intelsat-14 is next.

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