DirecTV Fears Explosion Risk From Satellite With Damaged Battery (spacenews.com) 163
DirecTV is racing to move its Spaceway-1 satellite out of the geostationary arc after the 15-year-old satellite suffered a crippling battery malfunction that the company fears could cause it to explode. From a report: DirecTV told the U.S. Federal Communications Commission that it does not have time to deplete the remaining fuel on Spaceway-1 before disposing of it by boosting it 300 kilometers above the geostationary arc, a region home to most of the world's large communications satellites. Spaceway-1 is a Boeing-built High Power 702 model satellite that was designed to last 12 years. Launched in 2005 on a Sea Launch Zenit 3SL rocket, the 6,080-kilogram satellite originally provided high-definition television direct broadcasting services from its orbital slot at 102.8 degrees west longitude. More recently, Spaceway-1 was being used to backup Ka-band capacity over Alaska. In December, an unexplained anomaly caused "significant and irreversible thermal damage" to Spaceway-1's batteries, DirecTV said in a filing dated Jan. 19. Boeing, the filing says, concluded that the batteries are at high risk of bursting if recharged, since the damaged cells can't be isolated.
What's a "Geostationary Arc"? (Score:3)
Never heard that term before.
I believe the correct way of characterizing it is a "Geostationary Orbit" in which the period of the orbit matches the period of the earth's rotation and it stays above the same spot over the Earth.
Saying that it's an "Arc", while it's colourful, poetic and visual, is wrong.
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Why do you think it's not still an arc?
https://en.wikipedia.org/wiki/... [wikipedia.org]
"This article has multiple issues." (Score:2)
I wouldn't call that a credible reference to "Geostationary Arc" - nor can I find any reference to the term "Orbital arc" other than that "Orphan" entry.
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Here, let me google that for you: https://www.google.com/search?... [google.com]
Wow! turns out tons of actual professional astronomers use that term. Guess you must feel a bit chagrined.
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Let me repeat my first question: Why do you think it's not still an arc?
Even if you haven't heard the term, doesn't it make sense if you take the two words separately? You know what geostationary means. Most of us (you might need to consult a dictionary) know what an arc is. What is your hangup?
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The question is whether a debris trail in geostationary arc (orbit) is more or less dangerous than debris in LEO orbits...
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I would think that if there's not enough fuel to safely collapse the orbit, that expanding the orbit as far as possible would be best, no?
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Well, looks like I'm a bit ignorant on this. Other comments indicate that more fuel would be needed to bring the sat into atmosphere than to expand it to the "graveyard orbit" that already exists just outside the geosynchronous orbit.
That's not intuitive to me. I was thinking that the "gravity well" would eat away at any orbit smaller than a geosynchronous orbit, and that nudging it towards earth would be easier to get the most movement (and eventually for it to crash).
Re:What's a "Geostationary Arc"? (Score:4, Informative)
Geostationary Orbit is roughtly 32,000 Miles above the surface. It takes a ton of fuel to bring it back down to the 500 miles that would be needed for atmospheric drag to bring it back into the planet, very few birds in Geo orbit have the fuel to deorbit because of the distance. Most dead geostationary satellites are pushed out of the equatorial arc (so the spot can be reused and they don't damage other birds) and eventually the planets gravity drags them to the Lagrange point where they are kept stable by the planets gravity. There's about 50 old birds sitting in the L1 Point IIRC.
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I guess I just didn't have a frame of reference in my head about the differences in distance involved in these two options.
When you say "bring it back down to the 500 miles" you're talking about for it to burn up in a timely, predictable manner, right? Wouldn't any orbit lower than geosynchronous eventually degrade and bring it back to Earth? Not from atmospheric drag, but from gravity? "Eventually" can be a long, long time, I understand, but even if it takes a few hundred (thousand?) years, wouldn't the
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But eventually you're going to interfere with LEO objects, and in the meantime you're addin
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planets gravity drags them to the Lagrange point
That would be a combination of the planet and the moon's gravity, or the planet and the sun's gravity. Lagrange points only exist because of the interaction of 2 gravitational fields.
Re:What's a "Geostationary Arc"? (Score:4, Informative)
Orbital mechanics are so counterintuitive that you either have a good grasp (from studying), or your gut notions will ALWAYS be wrong. You don't push down to lower an orbit, you push BACKWARD. Ninety degrees later in the orbit, the perigee will be decreased and the orbit will now be elliptical if it was circular before. Likewise, to raise an orbit, you don't thrust directly away from Earth. You push in the direction you are already going.
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Ninety degrees later in the orbit, the perigee will be decreased
Wouldn't that be 180 degrees (assuming your "push BACKWARD" means a retrograde burn)?
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Yes, sorry. I was thinking about movement in the north-south direction, which would show up 90 and 270 degrees after the thrust, the latter being in the opposite direction.
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Re:What's a "Geostationary Arc"? (Score:4, Insightful)
Download Kerbal Space Program
Play it for a bit
Never watch spaceships heading towards a planet again without screaming
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Once beyond geostationary orbit, the earth is rotating faster than the satellite. I think that then the earth's rotation will exert a tiny force the net effect of which increases the altitude of the satellite, because the earth's gravity field is not uniform.
In the absence of outside forces, if the earth were perfectly uniform and spherical and not deformed by the gravitational field of the satellite, the gravitational field of the earth bends the path of the satellite in a lossless fashion. The averages of
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300 kilometers above the geostationary arc, a region home to most of the world's large communications satellites
Most are GEO, not above GEO. Probably just poor writing skills.
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That is what it says.
Read up on how to use commas, since 'a region home to most of the world's large communications satellites' is being used to qualify 'the geostationary arc'
It's not a comma problem (Score:2)
I'm 500 miles away from home, in Dallas.
Do I live in Dallas, or am I currently in Dallas?
The comma doesn't answer that question. The sentence is ambiguous.
GP saw an ambiguous sentence, one that could be interpreted either way, and chose to interpret it as incorrect, while the other grammatically correct interpretation is the factually correct one.
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I'd read that as "currently in Dallas" because it would be simple to construct your sentence to say "I'm 500 miles away from my home in Dallas" if you meant the other.
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Nobody said there was a problem with the use of the comma. When he said 'use commas' he meant 'understand what commas mean'. The OP was complaining that the statement was wrong, when in fact the statement is correct (if you understand what a comma is).
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Ur dee hurhhhh
I am not disagreeing about the use of the comma, just how BrainJunkie interpreted it
He though that 'a region home to most of the world's large communications satellites' was describing '300 kilometers above the geostationary arc', and not 'the geostationary arc'.
If you want to be confrontational, then just drop the AC crap and be honest about it
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https://scholarship.law.berkel... [berkeley.edu]
https://www.telesat.com/about-... [telesat.com]
https://spacenews.com/arianegr... [spacenews.com]
Seems to be used in the industry quite a bit. What are your qualifications again?
Re:What's a "Geostationary Arc"? (Score:5, Informative)
A geostationary arc is an east-to-west part of the ring where it is possible to put a satellite in geostationary orbit. In this particular case, the term geostationary annulus would be more precise but the word arc is usually used because one typically specifies an arc where a satellite in geostationary orbit can provide adequate coverage for the desired areas on the Earth.
Re:What's a "Geostationary Arc"? (Score:5, Informative)
Note that the terminology only works for geostationary orbits. With regular orbits, the satellites appear to move relative to the earth, so their "arc" or "slot" is not fixed in space even if it's fixed relative to other satellites in the same orbit.
Isn't the fuel used to move the craft? (Score:2)
I am not quite clear on why the fuel cannot be exhausted (or nearly exhausted, the remainder vented) while boosting the satellite to the graveyard orbit. The graveyard orbit for geosynchronous orbit is higher than the geosynchronous itself.
Re:Isn't the fuel used to move the craft? (Score:4, Interesting)
My guess is that the thrusters would melt if they were burned for prolonged periods of time. That's a bit like asking "why can't a car burn through all of its fuel in 10 minutes?" Even if you red-lined the motor it would still take an hour to get through a fuel tank.
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I am not quite clear on why the fuel cannot be exhausted (or nearly exhausted, the remainder vented) while boosting the satellite to the graveyard orbit. The graveyard orbit for geosynchronous orbit is higher than the geosynchronous itself.
Wouldn't venting fuel (or anything, really) have an effect on the satellite's orbit, attitude, etc -- you know, action, reaction? Perhaps there's a specific procedure that prevents/counters this and they don't have time to execute it.
Anyone with more info care to elaborate?
Re:Isn't the fuel used to move the craft? (Score:4, Insightful)
Re:Isn't the fuel used to move the craft? (Score:4, Informative)
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Re:Isn't the fuel used to move the craft? (Score:5, Informative)
From the FCC Filing:
In December, Spaceway-1 suffered a major anomaly that resulted in significant and irreversible thermal damage to its batteries. Boeing, the spacecraft manufacturer, concluded based on all available data that the batteries' cells cannot be guaranteed to withstand the pressures needed to support safe operation of the spacecraft in eclipse operations; rather, there is a significant risk that these battery cells could burst. As payload operations have been terminated, the spacecraft has had sufficient power margin to avoid use of the batteries during sunlight operations. However, use of the batteries during eclipse is unavoidable and there is no ability to isolate damaged battery cells. The risk of a catastrophic battery failure makes it urgent that Spaceway-1 be fully de-orbited and decommissioned prior to the February 25th start of eclipse season.
TL;DR They can't vent all of the remaining fuel before the satellite moves into the earths shadow. Since it can only operate on solar power with out risking the batteries exploding, they satellite with loose power before all fuel can be vented.
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If you put it above geostationary, and it explodes, gravity will slowly bring all the debris back into geostationary orbit
Re:Isn't the fuel used to move the craft? (Score:5, Informative)
Dude. No. At the very least, play some Kerbal Space Program before trying to opine on orbital mechanics. In order to lower your orbit, you need to shed orbital velocity. Sure, some fragments might be ejected backwards along the orbit and lose velocity, but at GEO, orbital velocity is still 3KM per second! Nothing is going to fall back on its own.
300KM above GEO is the designated dumping ground for GEO satellites, and has been since we started putting stuff up there. It would take a large amount of delta v (and hence extra fuel) to deorbit from a geosynchronous orbit. Putting stuff in the dump orbit is safe and cheap.
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Re:Isn't the fuel used to move the craft? (Score:4, Informative)
To drop the satelite's perigee to low enough to be impacted by drag in a relatively short time (say months or years) would need somewhere on the order of 1500m/s of delta-v.
Boosting orbit to the graveyard orbit requires about 11m/s
Re:Isn't the fuel used to move the craft? (Score:5, Informative)
To expand on what isorox said, which is totally correct, you can think of it like this: it takes as much energy to come down out of an orbit as it takes to get into one, because orbits are about having enough horizontal speed so that even though you are still falling, you miss the thing you are orbiting. You can not just point the engines away from the Earth and fire them, and hope to hit the Earth.
I know that sounds weird, but it's how orbits work. You need to point the engines opposite the direction of your orbit, and reduce your speed. That's what lowers an orbit.
Now, a geosynchronous orbit is pretty high up, over 35,000 kilometers. The atmosphere ends at the Karman line, about 100km up. So we are talking about the difference between raising an orbit 300km, and lowering it by 34,900km. It takes more than a hundred times more energy to do the latter, 1,500m/s delta V as opposed to about 10.
For objects in low Earth orbit, it is absolutely cheaper to deorbit them than to send them into the graveyard orbit.
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Of course. But you still need enough delta v to bring the opposite side of the orbit down from 35,000 kilometers to under 100km. That's a lot more delta v than is needed to bring one side up 300km, then bring the other side up by 300km. And yes, I get that you only need enough delta v to bring one side of the orbit down below the Karman line, where atmospheric friction will eventually do the rest.
But let me just leave a reminder here that it takes over 9,000 meters per second of delta v to get into a LOW ea
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I think that you are ignoring the effects of the explosion on the satellite
Some parts will be accelerated towards Earth, and some parts will be accelerated backwards, resulting in lower velocity
In both cases, the parts will end up in lower orbits and potentially affect other satellites
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Parts accelerating towards or away from earth won't dramatically change it's apogee/perigee. Enough of a boom could cause it to intersect with GEO I guess, but I assume the graveyard orbit is high enough that that's a very low chance (i.e. parts wouldn't accelerate by more than 10m/s on an explosion)
If the explosion was big enough, in GEO or GTO, parts accelerating prograde could reach escape velocity (that would be enormous - 4-5km/s), parts accelerating retrograde could reach LEO or atmosphere (1.5km/s).
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Play some Kerbal Space Program. It will teach you much faster than any other method. Orbits are very counter intuitive. People simply aren't used to thinking about speeds of several kilometers per second. Don't try to use your Earth logic on orbits, you'll get it wrong.
For example, no single impulse ( like an explosion) can possibly change both the apogee and the perigee. Given a single impulse, you can change any other part of your orbit except where you are at. You will always return to that spot, whateve
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You are simply avoiding the topic by assuming that the satellite remains in one piece after the explosion
Each particle from the explosion will have its own vector and acceleration, some of them resulting in slowing (resulting in degrading orbit) and and direct insertion into lower orbits
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No, the pieces will not have a direct insertion into lower orbits, the best any piece can do is enter into a transfer orbit. First burn gets you transfer orbit, it is the second burn that is the insertion burn. You've simply failed to comprehend what I wrote. It's not about whether anything remains in one piece.
Here's the thing though. You can argue with me all you like. But ask yourself this: are you smarter than a NASA scientist? Do you know more about orbits? I will answer for you: no. You are not smarte
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People simply aren't used to thinking about speeds of several kilometers per second.
I don't think that's what gets everyone. It's thinking of space like a cone all the time that does it :)
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Please try to avoid mis-reading comments then going off half-cocked and insulting the author. Since it will use fuel to change the orbit, to either a higher or lower orbit, why is there an issue with remaining fuel after this orbit change has been accomplished?
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In short, because geostationary orbit is the outermost orbit we use, so sending it further out is the safest option. If you send the device back down toward earth, the potential debris field would very slowly cross the path of *every* other satellite in orbit. Keep in mind that it took the thrust of a very large rocket's final stage to get that sat out to the geostationary position. It would take an equivalent thrust to get it back down in any reasonable amount of time.
This image should make it clearer:
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I don't understand why it would take equivalent thrust to bring it down. Isn't gravity the reason it's hard to leave Earth? Doesn't gravity make it easier to bring things back down to Earth?
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I don't understand why it would take equivalent thrust to bring it down. Isn't gravity the reason it's hard to leave Earth? Doesn't gravity make it easier to bring things back down to Earth?
Gravity makes things move on a particular path, like a circle or an ellipse or a hyperbolic path.
If that path intersects with the Earth, then the thing hits Earth.
Generally, by slowing down relative to Earth, you make the path more elliptical until it the ellipse gets so skinny that it hits Earth.
Re: Isn't the fuel used to move the craft? (Score:2)
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But even at this height it is still a temporary solution and the moment the trust stops it will slowly start to decent.
Re:Isn't the fuel used to move the craft? (Score:4, Informative)
Well...no.
Depends on just what orbit it's in when they're done. It's not like atmospheric drag is meaningful up there in geosynchronous orbit. Nor is there any physical law that favours geosynch over any other orbit.
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No, that's not the way it works.
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OK, PLEASE identify how you calculated all of the vectors of the explosion and determined that NONE of the particles velocities will be reduced enough to cause them to enter a lower orbit...
Thought so...
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Of course some would enter a lower orbit, the amount of energy needed to get them to LEO or start getting drag from the atmosphere from GEO is about 1.5km/s.
Sure, it would only need about 10-15m/s for some debris to get down to GEO from graveyard, but the risk is obviously less in graveyard than leaving it in GEO.
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OK, PLEASE identify how you calculated all of the vectors of the explosion and determined that NONE of the particles velocities will be reduced enough to cause them to enter a lower orbit...
It was easy- I just listened to your stream of stupid and took the opposite position. And I never said "none", but nice try at putting words in my mouth.
It's a common misconception among the uneducated that stuff will fall to Earth after it enters uncontrolled/uncorrected flight phase. Some of it may, some of it may not. Some debris may have orbital positions that will take tens of thousands of years for it to decay enough to return to Earth, especially the smaller fragments.
So yeah, in summary, that's not
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Oh WOW, going from simply pedantic to pissing on people really isn't a good look for you
Thanks for assuming that you are the only person who knows that slowing an object will bring it to a lower orbit
fuck you for assuming that an explosion (the topic on hand) wouldn't accomplish that for enough of the mass of the satellite to be a worthy topic
Might I suggest that you start taking some turmeric and fisetin to keep you mental decline in check, all the cool BOOMERS are doing it these days
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How would exhausting the fuel prevent the battery from exploding?
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It wouldn't -but the battery exploding WITH the fuel still on board would make for a potentially bigger explosion with more far more debris.
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Would the batteries explode this would cause a lot of debris in the geostationary orbit which would endanger all working satellites in this orbit.
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That wasn't the question though. I already understand why the batteries are the risk. The OP was asking about venting the fuel. I wondered what the point of venting the fuel was, since the explosion risk is from the battery. Venting the fuel wouldn't reduce the risk.
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Would the batteries also explode you get a debris field in that same orbit.
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Why do you keep ignoring the things I write and responding with non-sequiters? I GET that venting the fuel is a bad idea, which is the reason I was asking WHY the OP thought we should do it.
Question (Score:2)
Instead of boosting it to a higher location where there is still the possibility of the batteries exploding, why don't they send it through the atmosphere to burn up?
I would really like satellites to be sent to the Sun when they reach end of life, but I understand why that is not economically, and possibly technically, feasible.
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An object in motion remains in motion. An object at rest, stays at rest. In order to lower its speed enough to descend from such a high orbit you would have to expend even more fuel than speeding up a little bit and entering a graveyard orbit.
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Instead of lowering its speed, couldn't they change its orbit? Yes, they would still be pushing it "down", but in more of an elliptical arc rather than straight down.
Wouldn't, at some point, this new trajectory put it in a position for gravity to do its job?
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One specific issue in this situation is that the satellite will theoretically explode when it uses its batteries. The lower your perigee, the more likely you are to enter earth's shadow. So the result would be a satellite crossing the orbits of hundreds of other lower satellites and maybe exploding every few orbits when it has to use its batteries as it passes behind the earth. That would be bad, even if it were possible. It's relatively safe up in Geosynchronous orbit right now since the debris would
Re:Question (Score:4, Interesting)
Same same.
Changing a satellite's speed changes its orbit.
"East takes you out, out takes you west, west takes you in, port and starboard bring you back." (_The_Integral_Trees_, Larry Niven) Best qualitative explanation of orbital mechanics and maneuvering you will ever find.
By which is meant: The basic direction of the orbit is defined as "east". A posigrade burn (burn with the direction of the orbit) increases your speed, and causes you to start increasing your altitude ("out"). A radial burn outward ("out) causes you to start increasing your altitude. The required speed to maintain your position over the ground is higher at higher altitudes, so you start "losing ground" and "falling behind" ("west"). A retrograde burn (burn against the orbit) decreases your speed, causing you to start descending ("in").
If you start from a circular orbit, posigrade and retrograde burns form a new periapsis or apoapsis 180 degrees away. Radial burns create a new line of apsides, connecting periapsis and apoapsis, 90 degrees away from where you burned.
"Port" and "starboard" refer to plane change burns. Your orbit will (must: physics) still have one of the two foci of the ellipse at the center of mass of the system, so you will cross your original orbit at the point where you did the burn, and again 180 degrees away from it.
The math is a bit messy. Best introduction is [Bate, Mueller, White] "Fundamentals of Astrodynamics" (Dover Books), but it assumes a basic familiarity with engineering mechanics. It was originally written as an Air Force Academy textbook. The authors, all Zoomie U faculty members, knew that the Zoomie U students had to take the mechanics class before they took the astrodynamics class.
The basic concepts can be taught, effectively, in a one-day seminar, although it will be like drinking from a firehose. Been there, did that. (I *THINK* the instructor was one of the Apollo Applications astronaut candidates who never got to fly. He was GOOD.)
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I would think going into a lower orbit would give a better chance at an eventual de-orbit.
Re:Question (Score:4, Informative)
Graveyard orbit takes about 1% of the delta-v that it would take to de-orbit back to Earth, or to escape Earth gravity.
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I understand that escaping Earth's gravity to send the satellite to the sun or deep space is completely impractical. Obviously the people who study this selected the graveyard orbits as orbits not useful for active satellites, but easy to reach with minimal fuel. I would still think that using the same fuel to slow down the satellite would cause it to eventually reach the atmosphere, but I suspect there are two problems:
1) It might take a *long* time for the satellite to reach the atmosphere with the same
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No. From geostationary orbit, it is significantly easier to escape into space (well, into a sun orbit anyway) than to get back into a low earth orbit. In fact, one of the typical routes into LEO is via space and aerobraking.
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No. From geostationary orbit, it is significantly easier to escape into space
It's about 4.3km/sec at GEO isn't it, so a delta-v of about 1300m/s, not much less than 1500m/s back to earth? Or am I remembering figures wrong?
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I jsut want to point out that probability says it will most likely end up in the Pacific, guidance or not. The chance of it striking a populated area is much much smaller.
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It takes a LOT of delta v, and therefore fuel, to drop the periapsis of a geosynchronous orbit into the atmosphere. And you'd need extra fuel just to pay the extra cost in delta v to get the first extra fuel up there in the first place, thanks to the brutal math of the Tsiolkovsky rocket equation. Meaning, you'd need many times more fuel to get a thing down from GEO, as opposed to pushing it a few hundred kilometers further out.
Putting things into a graveyard orbit is safe and economical. https://en.wikipe [wikipedia.org]
Re:Question (Score:4, Informative)
Because they do not have enough propellant to do that. It takes a delta v of about 9.4km/s to get into geostationary orbit, a bit less than half as much to get it down into the atmosphere, and again half as much to just make it eccentric enough to skim the atmosphere. So it would need maybe 1 to 2 km/s. But the propellant budget only reserves the 11m/s delta v required to get into a graveyard orbit.
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Instead of boosting it to a higher location where there is still the possibility of the batteries exploding, why don't they send it through the atmosphere to burn up?
Because they have nothing like the quantity of fuel to de-orbit it. To de-orbit, you would need something like 8000 feet/second of delta-velocity. beginning of life, they may have had a few hundred feet/second to maybe 1000 feet/second/ Not to mention, they also have very limited time to do it, since the batteries c
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Just Turn On MCAS (Score:5, Funny)
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The damage from the sound wave alone would be horrific.
But why? (Score:3)
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My guess is Samsung manufactured them.
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Might be interesting, but short of sending someone up to bring the battery back no one will ever really know. What matters is they don't charge the battery and cause the satellite to turn into multiple objects.
It could be anything that caused the failure such as just being old up to and including a paint flake going multiple miles per second hitting the battery and puncturing it.
We've seen these batteries before... (Score:2)
Shouldn't have tried to save money by using the batteries from the 787... :P
Spaceway-1 was being used to backup Ka-band capaci (Score:2)
Ka-band? More like Ka-boom!
Sorry. I'll let myself out.
Explode...Boeing-built (Score:2)
It begins to get old.
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I'm waiting for it to "clap back".