Reentry of International Space Station Batteries into Earth's Atmosphere
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I wonder how they would remake the battery chemistry if they were to use all the latest advancements.
“While the energy density is only around one third as that of a lithium battery, the distinctive virtue of the nickel–hydrogen battery is its long life: the cells handle more than 20,000 charge cycles with 85% energy efficiency and 100% faradaic efficiency” [1].
[1] https://en.m.wikipedia.org/wiki/Nickel%E2%80%93hydrogen_batt...
whoah
(Of course, it may not happen. Trucking hydrogen around is pretty inefficient and stupid: hopefully it will prove cheaper to pipe electrons around and generate hydrogen on site for whatever industrial process requires it.)
I owned a number of 2001 CNG Chevy Cavaliers around 2010, purchased through govt. surplus auctions. Their tanks were 3600 PSI. The tanks were certified for 15 years with no recertification. Nothing would stop working but they would no longer be certified. The tank would get hot while filling so I imagine the fatigue from many cycles of heating up was one factor in the certification period. Internal corrosion is another factor. If the natural gas compressor farm does not dry the compress gas then moisture will get into the tank and over many years will corrode the tank. There's a video out there of a CNG tank explosion at a fueling station somewhere in South America. No doubt metal fatigue plus corrosion contributed to that failure.
So 10,000 PSI for hydrogen is a lot of pressure to be transporting around in a vehicle for multiple years of heating / cooling and possible corrosion.I haven't heard the term faradaic efficiency before but im super super super happy to hear of it! I've been so curious, I just never had the term. Apologies if I mess this up but it seems to be the efficiency of turning input charge to stored charge. So curious but never figured out what kind of figures to expect from lipo or lifepo4.
I'm not sure if there's another term for efficiency of that stored charge being released/sourced, or if that tends to be >99% in most processes or what not.
Numbers are probably reasonably high (99+%) for commercial batteries, as the only two losses are ohmic (electric conduction through the cell, which is roughly the self discharge rate) and chemical (side reactions of electrolyte - which result in the degredation of the cell.
If you want so dive further down the rabbit-hole look up the Nernst equation.
Comes up more in electrochemistry than batteries, as energy efficiency is the dominant factor in the latter (watts_out/watts_in), noting that faradiac efficiency doesn't consider voltage.
https://ntrs.nasa.gov/api/citations/20050215412/downloads/20... has some more details.
The "deadface load" (a term basically not seen anywhere except in these batteries) seems to be related to discharging them to a safe voltage (possibly at end of life before disposal, or generally before maintenance).
"From 2017 to 2021, the nickel-hydrogen batteries were replaced by lithium-ion batteries." according to https://en.wikipedia.org/wiki/Electrical_system_of_the_Inter...
https://en.wikipedia.org/wiki/Nickel–hydrogen_battery ("...chemical reduction of Ni(III) into Ni(II) in the cathode")
There's a closed industrial city in Russia so heavy with nickel pollution, you can supposedly taste it,
- "“When gases are coming out of the pipes, you feel it,” says restaurant owner Eldar Aliyev. “From copper it has a sweet taste; from nickel, a different taste. Now, though, you taste it less.”"
https://www.theguardian.com/cities/2016/sep/15/norilsk-red-r...
https://en.wikipedia.org/wiki/IARC_group_1_Carcinogens#Chemi...
"The solution to pollution is dilution."
Let's examine a reductio ad absurdum of a medium term future where we have 1000x more space vehicles all taking space dumps into the atmosphere. Would that be best practice? Is there a better norm we could establish today?
This isn't a theoretical question. There's growing awareness among researchers that there's a need to research how the gasses and particles produced by rocket launches at scale could have an impact on the atmosphere.
https://newsinteractives.cbc.ca/features/2023/rocket-polluti...
So, there's about 1/2 a ton of nickel falling into the atmosphere every day anyway, 180 tons a year, already in the ballpark of your thousand ships.
I guess it comes down to a cost / benefit analysis?
A very tiny amount burning up at great speeds over hundreds of thousands of square kilometers is much more diluted than anything feasible on an industrial scale
It's likely cheaper to dispose of it in a controlled environment than it is to properly dilute it across the globe. And it's impossible to check that the "dilution" won't just end up being dumping it all in a single spot in the ocean devastating ecosystems
The CO2 output of a single car has little local impact and spreads throughout the atmosphere causing negligible global damage. The CO2 output of global industry has a significant impact because of the sheer volume being pumped out is enough to start affecting global temperatures. Other gases emitted by vehicles and industry can be bigger problems even on a small scale because they can concentrate in the local area.
The amount of pollutants in reentering batteries is not large enough to have an impact when diluted throughout the atmosphere. We’d need a lot more satellites for it to start becoming a major cause for concern.
There are two reports from Thailand at around that date
I'll add https://www.keeptrack.space/app/ to the list of suggestions. Although it may be more intimidating than helpful.
Neat site though, has 3D globe height tracking and in the upper right you can filter with the layer menu for "rocket bodies" and "debris". Very few sites I've found that can filter for debris objects. Be careful if your GPU is low-end though, it can be a resource hog.
Also, satellite.js and https://github.com/shashwatak/satellite-js/wiki/Sites-using-... which is where I found KeepTrack
I'm too far north to see much I think, but my parents live pretty close to the ground path. Maybe they can take some cool pictures.
Since the whole of Germany was marked in orange, I read the explanation was a low-likelihood threat warning caused by ISS battery debris (rather than an invasion from the East).
I had considered paraphrasing "I aim for the moon, sometimes I hit London..."
https://www.bbk.bund.de/SharedDocs/Downloads/DE/Krisenmanage...
https://gizmodo.com/massive-iss-cargo-pallet-reentry-earth-m...
All that comes home in current spacecraft (Dragon, CST, Soyuz, Shenzhou) is the small compartment with the people in it, and each of them even leaves the "orbital module"- all the fuel etc. behind to be burned up in the atmosphere. (Progress cargo flights burn up, but Cargo Dragon is actually recovered so some amount of cargo can be returned fully to Earth, but its mostly scientific stuff that is coming back in there right now as I understand it.)
Make everyone go "ooo, lookie at the science teacher doing experiments to see how [plant/animal] acts in space, everybody!" so they pay no attention to the spy satellite in the cargo bay (or the different spy satellite, or other equipment, being brought back.)
It’s easier to exit the Solar System than it is to boost mass into the Sun from any Earth orbit [1][2]. The atmosphere providing braking for “free” is a huge propellant saver.
[1] https://en.m.wikipedia.org/wiki/File:Solar_system_delta_v_ma...
[2] https://space.stackexchange.com/questions/3612/calculating-s...
It's expensive to get close to the Sun at low speeds (e.g. if you could land on it, or if you want a close orbit).
It's trivial to slingshot around the moon and impact the Sun at high speed.
The Moon's orbital velocity around the Earth is ~1km/s. A slingshot manoeuvre around the Moon isn't going to help nearly enough here.
One of the most efficient ways to get to the Sun is to leave Earth in the same direction it is going (and yes you can use a Moon slingshot to help here if you want) which will result in your rocket going further away from the Sun than the Earth. Once you're out in the region of the outer planets, you'll be travelling a lot slower and won't need to cancel out nearly as much velocity. Neptune's orbital velocity is ~5.5km/s, and if your rocket has an apohelion around there and a perihelion around Earth then you'll be travelling slower than that. However, it still takes a huge amount of delta-v to get out to the region of Neptune and then cancel out your velocity relative to the Sun.
Compare that to the amount of delta-v required to de-orbit an object from low Earth orbit. The object's velocity around the Earth is going to be about 7.9km/s, but it only requires a delta-v of around 100m/s to put it into a nice predictable atmospheric entry. That's comparatively nothing.
It's extremely difficult to impact the sun (at any speed), or get into a trajectory which does that.
(Technically it’s cheaper by a factor of three to go to escape velocity out of the solar system and then plunge back into the sun, but at that point, why go through the trouble and come back if your concern is trash disposal?)
If you can fenagle yourself into a highly elliptical solar orbit, then a relatively small retrograde burn at apoapsis could get you into the sun.
Getting to that orbit is more expensive than leaving the system.
We are moving really fast relative to the sun. Perturb your orbit to seem to intersect with the Sun and you’ll tend to fly past it. (Loose analogy: swimming in a current and aiming for a point on shore.)
Yes, a collision-only slingshot needs precision. But we're good at precision maneuvers with modern computers.
(it is correct that getting past Earth's orbit in the first place requires a bit of delta-v though, which I suppose I glossed over.)
That precision doesn’t get around the physics. Why do you think none of our missions to the inner Solar System have tried this?
Could you share a sample pair of trajectories that demonstrates this claim?
Slingshots steal orbital momentum. When one slingshots around Jupiter, one is stealing Jupiter’s orbital momentum about the Sun. (It only works in one direction.)
Slingshotting about the moon to gain velocity relative to the Sun doesn’t work. That said, I’d love to see an orbital solution for cheap decay into a solar-impact trajectory. (Orbital mechanics are complex enough that nobody should feel comfortable entirely precluding subliminal sets of solutions.)
Most slingshot maneuvers do gain or lose momentum relative to the Sun! And they do work in both directions (gain and lose) – we've used them for quite a few probes, e.g. MESSENGER.
> Slingshotting about the moon to gain velocity relative to the Sun doesn’t work.
It does, as used by e.g. STEREO [2].
All that said, they're still not "free" in terms of delta-v by any definition. They provide an efficiency gain, but sending stuff to the sun is still prohibitively expensive for anything other than lightweight scientific probes.
Why not? And you don't actually want to gain velocity, you'd want to change direction.
I agree that shooting stuff into the sun is not worth it, if you just want to get rid of it.
If you fall towards an object and then fall away from it, there is no net force. You can’t bleed or gain delta-V simply by falling into an object and then falling away from it.
The reason planetary slingshots work is you’re “dragged” along with their orbital velocity about the Sun. You can be clever about using that to reduce the delta-V to the Sun. But it’s still more than system escape velocity.
But you can change direction.
This is analogous to trying to turn a plane by only yawing. Or travel in a current by turning your head.
This guy [1] is wrong. Delta-v comes from Tsiolkovsky’s rocket equation, which in turn derives from Newton’s second law and the conservation of linear momentum. It’s incredibly fundamental math that you can’t cheat by changing direction. (You’ll change orientation and keep going where the math says you will. Because you’re going sideways relative to the Sun at an incredible velocity, the inheritance of every atom in the Earth’s sphere of influence, including the Moon.)
A very wide variety of angles are frequently used in slingshot maneuvers, simply by controlling how close you get to the Moon or more often the planet.
Are you referring to plane change? That isn’t a cheat code for delta-v.
I’m genuinely curious for your math.
Apparently, very little of that is expected to come down, courtesy of the 8 km/s of kinetic energy it has turning into heat in a very short amount of time.
I image it will be the same for the battery pallet, aided with parts being thin skinned & pressurized.
They probably ought to put a number to this. When a person says "odds are very low," they usually mean like 1:1000. When a scientist says it, they mean like 1:100000000000000.
If yes, wouldn't it be possible to move it to a higher, safe orbit instead? Maybe even taking it to Moon's orbit?
But the hardware will not last forever, it has taken a beating from micrometeorids, radiation, extreme temperature changes etc. At some point it becomes too risky and expensive to operate.
The ISS must be ~ 2/3 (?) of escape velocity and out of the densests layers of the atmosphere, so it seems reasonable (to me, at last :) that the power needed to boost it is much less than what it took to put it where it's at.
GEO is very densely populated, maybe a repair shop in the neighborhood would attract some customers.
If it was practical, they'd be doing it instead of Artemis.
Just like it was in 1950!
https://www.space.com/nasa-darpa-nuclear-thermal-rocket-drac...
Also, if you pick a random place on earth, there are no humans there. You might find roads, mostly, it is water, and if not, the only sign of humand life is most likely roads, or nothing at all. I do not recall who used google earth to test this, and of course, a large scatter area for debris would alter this probability equation.
Still, unless actually maintained in some form, there will be a risk of the ex-ISS complex shedding stuff over time - either due to collisions or possibly material degradation, which could still be an issue for anything below or crossing the new higher orbit.
The thermal regulation system was designed for 45 minutes in day followed by 45 in night, the communications were designed around being within realtime communications range (eg astronauts remoting into PCs on the ground for personal browsing, so as to reduce risk to the station's own computers) and there are no reasonable crewed or uncrewed vehicles available to maintain the station at that distance. The station is also likely to struggle to deal with docking to either lunar lander, given their size.
We can't turn it into an orbital museum piece without maintaining it, lest it fall apart and cause a massive amount of debris.
We're still early in our spacefaring days, there are still many more historically relevant space stations ahead of us, some of which we may actually have the ability to properly preserve. For the ISS we'll have to settle for the astronaut training models used by NASA.
But yeah, it's not a Gravity scenario, either.
Prediction specified down to the minute with but the error bars are measured in days.
This is a fundamental problem with chaotic probability.
While the hysteria was a little overblown, there was a pretty important difference, these batteries were heavy and dense, making them pretty likely to pretty much entirely burn up on the way down. The rocket body was large and lightweight, so it was more likely to have debris survive all the way down to the surface.
On top of that, this was an exceptional circumstance, the planned controlled disposal ended up becoming unavailable and potentially grounded for months, while the batteries were an increasing safety hazard. On the other hand, that rocket was intentionally designed this way with no regard for attempting to perform a controlled reentry.