> 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].
"It differs from a nickel–metal hydride (NiMH) battery by the use of hydrogen in gaseous form, stored in a pressurized cell at up to 1200 psi (82.7 bar) pressure."
That's nuts. 10k PSI. My car has a a CNG tank that is at several hundred PSI and that makes me nervous when filling it up, but 10,000 PSI is way way more than this.
This is one of the reasons hydrogen cars are unlikely to achieve any widespread deployment. But the new proposal is hydrogen-carrying trucks, which is better (larger tanks and bigger scale means more and better maintenance than a typical passenger vehicle can justify) but also, it means extremely high pressure hydrogen tanks on the road with your traffic.
(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.
Fwiw, EVE's lf560k lifepo4 cell is finally out now & supposedly good for 12k cycles.
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.
Faradiac efficiency is essentially electron counting: e.g. at 100pct efficiency you need a mole of electrons to convert a mole of Li+ to Li0. At 50pct 2 moles. Moles of electrons can be converted to amp-hrs for a more conventional unit.
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.
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).
Probably the same, NASA has been making batteries out of Lithium where appropriate for 60 years, so they chose that chemistry for a reason (most likely its non-toxicity and relative safety for a crewed space station)
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.”"
OK thats a big number, but we are talking about spreading heavy elements around the atmosphere, some portion of which will end up in the soil, then in us.
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?
If de-orbiting is your concern, then I would suggest taking a step back and considering the impact on our atmosphere of increasing the number of launches.
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.
The amount on the ISS is likely extremely tiny compared to any waste produced in the manufacturing of mass consumed goods
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.
Yesterday I saw a large object burning up in the atmosphere over Thailand. Is there a website that tracks objects that have recently burned up in the earth's atmosphere where I could look it up and see if I can find what it was?
I'd give https://in-the-sky.org/satmap_worldmap.php a try, it might not contain the debree you are looking for however. Make sure to check the checkboxes below the map! At least you can go back in time and maybe spot the deorbit procedure or similar.
Looks like related events. An orange fireball at 19:00 in NE Bangkok and then a green fireball in SE Bangkok at 21:00. Fireball reporting's a cool one I had not seen before.
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.
I think that was it. Timing is right. I saw a different angle though. From my perspective I couldn't see that it had broken apart into multiple pieces. I saw it to my north, moving slowly west to east across the sky.
I got an alert about this in KATWARN yesterday. It was kinda funny and curious for a second that this wasn't about yet another WW2 bomb, but instead an alert about... objects from space? Hah.
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.
At 1719 CET yesterday, the NINA citizen warning app ( https://www.bbk.bund.de/EN/Home/home_node.html ) triggered a German wide alert. Usually, small regions are marked to indicate bad weather situations like storms, floods, I have never seen a country-scope alert before.
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).
Funny thing is, the ground track of this debris goes right over both London then Berlin after the estimated reentry point. Any late pieces just might reenter over one of those two WWII rival cities.
"Affected" is a strong term. The line along which re-entry was predicted to occur is three times the circumference of the Earth (as you can see in the OP article), and a small fraction of that line passes through the borders of Germany.
“The uncontrolled disposal of the pallet, however, was not part of the original plan. It was made necessary by a disrupted spacewalking schedule following the failed launch of a Soyuz rocket in 2018, which forced NASA astronaut Nick Hague and Roscosmos cosmonaut Alexey Ovchinin to make an emergency landing in the Kazakh steppe. This event led to a backlog in the disposal of such equipment. Normally, old batteries would be placed inside an HTV and jettisoned from the ISS to burn up on re-entry.”
The current tragedy has the batteries just minutes away from hitting London or Berlin. A controlled reentry would be much further from large population centres.
That's what I get for typing on a phone with autocorrect. The word should have been "trajectory" though I concede that I may have spelled that incorrectly enough for the autocorrect to mistake the word.
Is it not possible (yet) to return them to the surface in a controlled manner via a SpaceX capsule of some kind? (Or just not seen as worth the expense?)
The Space Shuttle was weird and unusual in that it was the only spacecraft ever capable of bringing significant payload back down to Earth. It cost a whole lot of payload up mass to get that capability (every flight had to carry the reentry protection for that huge payload bay, even if you didn't actually need it) and it was used on several occasions- things like Palapa and Westar (STS-51A), Solar Max, and all the SpaceLab missions- but on many other flights the payload bay came home ~empty and all that protection weight could have had better uses.
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.)
That's because the Space Shuttle was designed to be a spy-agency space cargo van (with parts from nearly every congressional district to guarantee it would sail through congressional approval despite being hideously expensive and impractical.)
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.)
The only such capsules available are already being used to return astronauts. There isn't enough spare capacity for returning much else -- and certainly not 2.6 metric tons of batteries.
It's basically free to let the orbit decay. It is hundreds of millions or billions of dollars to return it to earth. It doesn't make sense to spend a billion dollars on literal trash.
I would imagine that breaking them up instead of dropping as a single unit could be beneficial - higher surface to volume ratio, leading to more thorough burn up in the atmosphere.
> prohibitively expensive to just boost them into the sun or elsewhere, while in low orbit?
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.
The Earth's orbital velocity around the Sun is ~30km/s. You need to cancel almost all of that out in order to shift to a trajectory that intersects the Sun, and that trajectory still has you impacting the Sun at quite some 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.
How does delta-v prevent you from aiming in a direction that intersects with the sun? That's all that's required for trash disposal. You aerobrake in the solar atmosphere, if your want to think of it that way
To reach the sun, you need to shed a lot of kinetic energy - and given that you’re in a vacuum on most of the way there, the only way to do that is through a lot of deceleration, which is really the same thing as retrograde acceleration, and maybe some gravitational slingshots, but these aren’t free either (you need delta-v to execute them) and therefore have limited gains.
(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?)
> To reach the sun, you need to shed a lot of kinetic energy - and given that you’re in a vacuum on most of the way there, the only way to do that is through a lot of deceleration, which is really the same thing as retrograde acceleration
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.
> aiming in a direction that intersects with the sun?
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.)
"Aiming in a direction that intersects with the sun" requires a huge momentum change when an object already has a large orbital velocity around the sun.
You don't need to just "get past Earth's orbit", you need to deorbit out of Earth's orbit around the sun if you want to reach the sun. This requires a much higher (at least double) delta-v than leaving Earth's gravity well alone.
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.)
> Slingshotting about the moon to gain velocity relative to the Sun doesn’t work. (It only works in one direction.)
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
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.
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.)
No, the direction change is relative to the Moon, not your orbit around the Sun. The Moon, when retrograde, is still moving forward around the Sun. Your orbit will become more eccentric, but the periapsis won’t even make it past Venus’ orbit.
It's not about "gain velocity", but "change angle".
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.
Yes. LEO is "halfway to anywhere" but only halfway, boosting up to a high earth orbit requires significant amounts of fuel, getting all the way out of earth's gravity well takes more, and to get to the sun would take even more than boosting all the way out of the solar system. If they put them in an orbit "next to" the ISS then atmospheric drag would eventually carry them down until they burned up (even the ISS itself needs to be regularly boosted or it would eventually fall down) but that way it's unpredictable and uncontrolled (and there's always the risk of them hitting a satellite or something), a planned re-entry burnup is generally thought to be safer.
I recently saw in person a non-flight part of a Vega satellite dispenser - rather solid looking 80+ kg aluminum ring like shape, that during a normal flight profile burns up about 100 minutes after lunch via controlled re-entry of the upper stage.
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.
> While some parts may reach the ground, the casualty risk – the likelihood of a person being hit – is very low
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.
The ISS is boosted to a higher orbit every few months using on board thrusters, otherwise atmospheric drag would have deorbited it a long time ago.
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.
I didn't mean to keep operating it, but to use it for spare parts or as a container, to shield new gear from those perky micrometeoroids.
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.
Not even remotely possible in a practical sense, for so many reasons. Summed up by it wasn't designed for it. Radiation, fuel consumption required for the delta V, supply vehicle capabilities, generation of space debris, regulatory compliance, design lifetime, etc.
If it was practical, they'd be doing it instead of Artemis.
The fuel needed to get two small capsules to the moon is expensive, since you start on earth. The fuel required for all of the ISS is way too much.
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.
A higher orbit may be possible, but maintaining any orbit comes at a fuel cost. A moon orbit would be hugely costly, and again would require ongoing fueling to maintain a 'permanent' orbit.
There are geo stationary orbits that don’t degrade. If you’re orbiting earth or moon they will always be tugging at it
Edit: as mentioned above getting it to geo stationary would be costly. It’d also be in a place hard for missions to reach. Also meant Lagrange point not geostationary
You're not stupid. Atmospheric drag drops off rapidly as you go higher. The ISS would deorbit within a few years due to atmospheric drag at it's current altitude, but if you got up to ~1000km it would take thousands of years to decay.
That could work & would be substantially less crazy like the suggestions to put it to GEO and Lagrange points.
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.
Not only was it not designed for those environments, what's the point? The parts are aging, machines that old struggle even without the increased stresses of space, and as the station ages, more and more effort has to be spent on maintenance and safety.
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.
Saw this on the news yesterday here in Germany with a headline like "ISS debris might hit Earth" and briefly feared a Gravity-like scenario - but the speakers's tone of voice didn't fit, and soon it became apparent that it was "just" a battery pack...
"The reentry will occur between -51.6 degrees South and 51.6 degrees North" -> "We have no f** idea of where or when it will come down, but at least we can assess it won't hit Santa Claus".
That's partly because the drag effect of the atmosphere depends on the solar activity. Meaning, depending solar activity an object will start aerobraking higher up or lower down in the atmosphere. That of course drastically impacts the time it takes the object to fall out of orbit and since we can't really predict solar activity we cannot precisely predict when nor where this battery pack will hit the ground.
Presumably you're comparing to the hysteria around the rocket falling back to Earth from some time ago.
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.
Curious that you phrased it as a hypothetical. And I don't remember any hysteria about pollution from China's reentries, just some about their developing space capabilities in general.
I wonder how they would remake the battery chemistry if they were to use all the latest advancements.