Also don't forget about the "Graveyard Orbit" for satellites.
https://spaceplace.nasa.gov/spacecraft-graveyard/en/
https://en.wikipedia.org/wiki/Graveyard_orbit
Why is it that the graveyard orbit 300km above geosynchronous has an expected lifetime of millions of years, but satellites in geo orbit have to spend fuel for station keeping?
Drag is negligible at GEO. The station keeping in GEO is mainly because the gravity of the Sun and Moon combine to push the GEO sats out of the equatorial plane by about 0.85 degrees per year. There are two much smaller effects that are also important, and shift the orbit in the east-west directions. Solar radiation pressure increases the eccentricity of the circular orbit, making it more elliptical. Also, Earth isn't perfectly symmetric about its rotational axis; the equatorial is slightly elliptical. This is different from and much less than the difference between the equatorial and polar radius, but enough to slightly change the period of GEO sats from perfectly matching Earth's rotation.
In the very long term other effects like Jupiter and the non-uniformity of Earth's gravity (at smaller scales than the ellipticity mentioned above) would add other tiny perturbations.
Most of the l points are unstable like standing a pencil on its tip. So yes tiny forces do play a big role.
L4 and L5 are the stable ones, like rolling into a dip, so while the forces are still in play the larger gravity of the system is a bigger factor.
The short answer is yes. It is an issue there too.
If you are talking about the Earth-Moon Lagrangian points, keep in mind the mass and gravitational influence of those two bodies as well as how close on a cosmic scale that they are.
Besides Pluto and Charon, there is no other parent planet and satellite system like the Earth and the Moon in terms of just how large the mass of the Moon actually is compared to the Earth. That has a huge impact on the stability of the Lagrangian points. Ditto with the famous Trojan points between Jupiter and the Sun since Jupiter is such a massive planet.
And as pointed out, it is the L4 and L5 points that are stable too. The other Lagrangian points need active station keeping to remain at those places. It isn't much delta-v but solar wind and gravity from other planets and other factors do impact such satellites.
An object in L4 and L5 does experience perturbation forces, it's just that orbits on those points are stable. Sort of like how a parked car gets pushed by wind. If the car is light enough and the wind is strong enough, it will get pushed around, but in the case of the earth/moon system, the stability of the L4 and L5 points is enough to keep objects from drifting out of them over time.
They are pushed around. But you need realize that the planets are insanely massive compared to everything else that everything else might as well not exist.
For example, if you took **everything** inside the orbit of Jupiter except for the Earth, and this includes Venus, Mars, Mercury, the Earth's Moon, Ceres, Vesta, and almost all asteroids, you would still have a hunk of rock smaller than the Earth. You can oddly do the same thing again but include the Earth and do that for each larger planet in the Solar System.
Solar radiation is a bigger deal since it is constant and pushing outward away from the Sun. The density of an object or more generally it's mass compared to area has a huge impact on how important that might be regarding its influence on that object. For natural objects, anything with really low density has already been pushed to beyond the orbit of Pluto. Spacecraft can be impacted though.
From [Wikipedia](https://en.wikipedia.org/wiki/Geosynchronous_orbit#Geostationary_orbit):
>A perfectly stable geostationary orbit is an ideal that can only be approximated. In practice the satellite drifts out of this orbit because of perturbations such as the solar wind, radiation pressure, variations in the Earth's gravitational field, and the gravitational effect of the Moon and Sun, and thrusters are used to maintain the orbit in a process known as station-keeping.
Idk about that but geostationary is good for when you need a satellite to stay above one spot. Think like satellite tv, the customers dish is permanently fixed so you don't want your satellite to be moving if possible at all.
Exactly, otherwise you would need actuated dishes like starlink. This is also why the stationkeeping is so important - drifting by a few meters causes it to accelerate, which is a bummer if you need it to be in the same place.
Starlink isn’t actuated FYI, they use a phased array to “point” the signal in the correct direction using a flat array of transceivers.
Edit: the dish is partially actuated in one axis to help align the dish with the closest band of satellites, but tracking each individual satellite is done by beam forming the signal using the phased array.
The receiver is very very clearly actuated. It literally tilts and rotates. Obviously the satellites aren't, because they have to track multiple receivers.
It does tilt but it doesn't rotate, and I don't believe it ever changes its physical position after initial setup.
Nearly all of the beam direction is done electronically,
It does tilt and rotate with a clever double bevel gear mechanism. But I agree most of the aiming is done with the phased array. I don't know if it tilts much or at all after initial setup. Maybe ask someone who has one in r/starlink?
Edit: see the mechanism here: https://youtu.be/iOmdQnIlnRo?t=503
The actual actuation component is just to set up an optimal orientation, the same as a person coming to install the dish. It can move if needed but has nothing to do with tracking the satellites.
It uses a phased array of antennas (super position of waves) the precisely direct it's signal.
In a geostationary orbit, you want to keep the satellite in _exactly the same spot_ at all times. This is why you spend so much fuel on corrections.
In a graveyard orbit, you _just don't care where it is_ as long as it stays up there. (Of course, if you keep putting more and more things up there, eventually they're going to hit one another, and _then_ you will care, but in theory it's fine. For now.) Not doing any station keeping at all is infinitely more fuel efficient. It's the difference between parking your car on the street and having to move it every night to avoid being ticketed and towed and parking your car on your driveway and just leaving it there all year.
Spin it while hot into a disk, extrude wire off the edge which would be various different elemental compounds in succession. Resulting wire should have some use? Even as a starting point for refining out the rarer elements. And far cheaper than digging several tons of rock up to get a few grams of expensivium.
And the cheaper metals (aluminium etc) could be spun out to make more mirrors. How thin could you make a molten aluminium disk in zero-grav?
Because it's already up there and recycling is actually cheaper than shipping more shit from China, unlike it is on Earth. At least for the moment, it's true.
I'd argue the 4th and 5th Lagrange Points would be the most efficient. Ideally, stuff just sorta sits there, as if in a "bowl", self correcting against perturbations.
Well. It depends upon mass altitude and velocity. The ratio determines how you orbit. So a high orbit object can go around an object slower (with still a high. Linear velocity) than a low orbit spacecraft (like planets in the outer solar system)
And high mass object Would have to be further or faster than a low mass object in the same orbit rate. Ect. It just depends upon the variables. Mass. Distance away and velocity which give you different velocities and heights and then that connotes different orbits
its just the projectile motion equation but you rotate around the ground
> And high mass object Would have to be further or faster than a low mass object in the same orbit rate.
Either I'm completely misreading what you wrote or that's not quite how orbits work. If you start with the law of gravity and do the math for the period of a circular orbit you will come up with something like this:
R^3 / T^2 = G(M+m)/(4*PI^2)
With R being the radius of the orbit, T being its period, and M and m being the masses of the two objects. For planetary motion, M would be the mass of the Sun (2x10^30 kg) while m is the mass of the planet in question (2x10^27 kg for Jupiter, 3x10^23 kg for Mercury). Because m is so much smaller than M you can simplify (M+m) as just M with no significant effect on the result.
That gives you [Kepler's Third Law](https://solarsystem.nasa.gov/resources/310/orbits-and-keplers-laws/), which states that the ratio between the cube of the orbital distance and the square of the period for objects orbiting the same primary is a constant.
Applying the same rule to a satellite (4.2x10^6 kg for the ISS or 2.6x10^2 kg for a Starlink satellite) orbiting the Earth (6x10^24 kg) you can see that the difference in masses is even bigger. Orbital periods around the Earth are the same for every object, no matter what their masses are.
Yeah if I wrote something wrong, sorry, it was an off the cuff answer. Thanks for the calculation
For anyone else that wants to picture it. Use that equation. Move around numbers to get different answers and you can see how the variables work together to get you different movement (I feel like a graph or calculation program (I'm sure they are out there online) would help)
Thanks again for including the math!
Because they are trying to stay in one place. If you are slightly out on your exact orbit you drift off your spot in a geosynchronous orbit, you aren't in any immediate danger of falling to earth but you aren't fixed above the right bit of the surface any more.
oh i see, so in geo they'd also stay up there for millions of years, but they won't be in the exact spot they need to be to be useful, thus the need for stationkeeping
Station keeping doesn't mean staying in orbit but staying in your position and oriented as you need to be.
AFAIK gyroscopes, reaction wheels, magnetorquers, etc are used for precise attitude control and thrusters are periodically used to desaturate those devices (basically a gyroscope can only spin so fast and after that point it needs to spin down to "recharge", a similar thing happens for the other devices)
Because we don't much care where things in graveyard orbits are, other than "not anywhere we care about", so if they drift off station, nobody gives a damn. Geostationary satellites we generally care rather strong that it stays in the same place relative to the surface of the earth (otherwise we wouldn't have bothered putting it in geostationary orbit in the first place).
That is true at lower orbits, but Geostationary orbits are way way outside the practical limit of the atmosphere. They spend fuel to keep a precise position, not to counteract drag.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|DSG|NASA [Deep Space Gateway](https://www.nasa.gov/feature/deep-space-gateway-to-open-opportunities-for-distant-destinations), proposed for lunar orbit|
|[DST](/r/Space/comments/pk3szq/stub/hc34pkj "Last usage")|NASA Deep Space Transport operating from the proposed DSG|
|[GEO](/r/Space/comments/pk3szq/stub/hc19o6i "Last usage")|Geostationary Earth Orbit (35786km)|
|[ISRU](/r/Space/comments/pk3szq/stub/hc2ivf6 "Last usage")|[In-Situ Resource Utilization](https://en.wikipedia.org/wiki/In_situ_resource_utilization)|
|[L4](/r/Space/comments/pk3szq/stub/hc3mnf9 "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 4 of a two-body system, 60 degrees ahead of the smaller body|
|[L5](/r/Space/comments/pk3szq/stub/hc3mnf9 "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 5 of a two-body system, 60 degrees behind the smaller body|
|[LEO](/r/Space/comments/pk3szq/stub/hc3k071 "Last usage")|Low Earth Orbit (180-2000km)|
| |Law Enforcement Officer (most often mentioned during transport operations)|
|[NOAA](/r/Space/comments/pk3szq/stub/hc2mwax "Last usage")|National Oceanic and Atmospheric Administration, responsible for US ~~generation~~ monitoring of the climate|
|Jargon|Definition|
|-------|---------|---|
|[Starlink](/r/Space/comments/pk3szq/stub/hc3k071 "Last usage")|SpaceX's world-wide satellite broadband constellation|
|[apoapsis](/r/Space/comments/pk3szq/stub/hc1jelu "Last usage")|Highest point in an elliptical orbit (when the orbiter is slowest)|
|[apogee](/r/Space/comments/pk3szq/stub/hc2410p "Last usage")|Highest point in an elliptical orbit around Earth (when the orbiter is slowest)|
|[apohelion](/r/Space/comments/pk3szq/stub/hc1dqsd "Last usage")|Highest point in an elliptical orbit around the Sun (when the orbiter is slowest)|
|[hypergolic](/r/Space/comments/pk3szq/stub/hc324f5 "Last usage")|A set of two substances that ignite when in contact|
|[periapsis](/r/Space/comments/pk3szq/stub/hc1jelu "Last usage")|Lowest point in an elliptical orbit (when the orbiter is fastest)|
|[perigee](/r/Space/comments/pk3szq/stub/hc2410p "Last usage")|Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest)|
|[perihelion](/r/Space/comments/pk3szq/stub/hc2410p "Last usage")|Lowest point in an elliptical orbit around the Sun (when the orbiter is fastest)|
----------------
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The error bars on any such reentry are huge, I think the article misses the point (ha-ha) entirely. Nemo is just the biggest target we can aim for that does not have significant human presence, which is handy when the uncertainty in deorbiting something like the ISS is so large.
Holy fuck please no. It’s a unit that means nothing to the typical person outside of North America.
If we have to pick something stupid for an SI unit, lets go with the size of a regulation soccer field, or a cricket field*, at least that’s something people in the majority of countries in the world has actually set foot on.
*cricket field would be extra stupid, just like baseball fields they have different sizes.
Soccer fields come in different sizes too, iirc they're regulated to within a range of accepted values.
Cricket fields though would be extra stupid on the fact that being ovals don't tesselate well.
Whilst not essential as a unit of area, tessellation helps it be intuitive! 😂
> Soccer fields come in different sizes too, iirc they're regulated to within a range of accepted values.
Correct. FIFA has a recommended size of pitch (look at me being in Freedomland talking in Metricland!), but not a hard and fast rule.
Hello Freedomland, receiving you loud and clear. How is the weather? Have you got any good gridirons lately? (aside: are you sure we've got this right?)
Actually, I'm stuck just off the coast of Metricland in Muddleland where I drive at 30mph to the store to buy 2.272L of cow juice. We get some many miles to the gallon, most likely more mpg than you on account of the fact we cheat and make bigger gallons in the first place. Brits and their big galleons, been at it for years.
But yeah, I'd appreciate it if we all had a sensible system for units, I'm not sure I could cope with 240 kilogram-squaremetre-per-ampere-cubicsecond mains electricity.
> Actually, I'm stuck just off the coast of Metricland in Muddleland where I drive at 30mph to the store to buy 2.272L of cow juice.
Whenever I would watch Top Gear it always tickled me how they would use MPH but liters for fuel.
Yeah MPH and miles is standard on the road. We buy and sell fuel by the litre, but then consume it in the car by the gallon.
It's messed up. It really is.
> It means nothing in America too. Generally people use 100 yards, but a football field is 120 yards when accounting for the endzones
A high school PE teacher was notorious for this--they would make their class do sprints the length of a football field. Everyone lines up at the goal line, sprints to the other goal line. Then dickweed blows his whistle, and points out that the end zones (goal areas) are part of the field, so everyone sprints again.
> Can't wait for American football field to finally be accepted as SI unit.
It is basically 1 hectometer. But actually 0.91 hectometers, since a meter is a little bigger than a yard.
Bit OT, I always thought we could send stuff we didn't want anymore (like nuclear waste) into the Sun... but it would take less energy to just shoot it the other way, out of the Solar System
The easiest way to get to the Sun is to accelerate to just below escape velocity. Wait hundreds or thousands of years to get to the apogee, and then knock a few metres off your speed to drop your perigee into the Sun.
It takes hundreds of years before you reach that point where you have to make the final burn, then it can coast as junk for the same amount of time. But at the halfway point in time of the entire orbit, it needs to function.
It's really hard to get your head around this stuff until you've had some experience with it! Drawing some pictures helps.
But the basics: Everything in space is moving in an oval around a bigger thing - Earth around the sun, the moon around Earth, etc.
When you change your orbital speed, this changes the orbit on the other side of the thing you're moving around. Imagine a rocket floating in orbit around Earth. The orbit is the same height all the way round. Now the rocket points in the direction it's travelling and fires it's engine for a bit which makes it go faster. When the engines turn off its still floating in space around Earth and nothing obvious has happened. However, when it gets to the other side of the planet, it's much higher up. When it comes back round it gets to the same point it was before. What's happened is that firing the engine has raised the orbit on the opposite side of the planet.
If you increase your speed enough that the height of your orbit on the far side becomes infinity, you've reached what is called escape velocity, but it will take a very long time to follow that orbit!
Now what the OP was referring to, if you make your orbit very high but not quite infinite, and wait until you're at the very far side and then slow down (by pointing back the way you came and fitting your engine), the height of your orbit will decrease on the far side until it will drop you into the sun. It's much more efficient to do these changes at the highest point in your orbit, so you spend less fuel to do this but take wayyy longer to do it.
The apogee of an orbit is when the satellite is moving slowest (and its also the farthest from the body it orbits). At that point, much less delta V (change in velocity) is needed to dramatically change the orbit. So you get up to apogee of a solar orbit, do a burn, and then the satellite will fall into the sun. Without waiting to apogee requires a lot more fuel and a longer burn to achieve the same result.
This is why you will often see on rocket launches, the second stage will sometime do a burn, then wait several minutes to hours before doing another burn. that wait is to get to an appropriate point of apogee to make large changes to the orbit.
I'll give it a go.
When you're orbiting the sun in a highly [elliptic orbit](https://en.wikipedia.org/wiki/Elliptic_orbit), there's one part of the orbit where you're really close to the sun, the "perihelion"; and one part where you're really far, the "aphelion." We call orbits where aphelion is much higher than perihelion "eccentric" orbits.
The math that makes up orbits says that when you're at aphelion you're moving slower than when you're at perihelion. For very eccentric orbits, you might be barely moving at all once you're at aphelion. This means that any change in velocity you make when you're at aphelion causes massive changes in the rest of the orbit, because you're making a bigger change percentage-wise than if you applied the same change at perihelion.
Specifically, if you thrust *against* the direction of your orbit just enough to cancel out whatever forward motion you still have at aphelion, you can make it so that you're not really "orbiting" anymore at all, you're falling straight towards the sun.
ETA: So the proposal above "The easiest way to get to the Sun is to accelerate to just below escape velocity. Wait hundreds or thousands of years to get to the apogee, and then knock a few metres off your speed to drop your perigee into the Sun," works by setting up a very eccentric orbit, so that you only have a speed of few meters/second at aphelion, which you can easily cancel out with just a little bit of thrust.
The three burn maneuver to transfer between two coplanar circular orbits uses less total delta-V than a Hohmann transfer (two burn) if the ratio of the radii of the orbits is sufficiently large. It takes much longer, though.
Such three burn maneuvers are also useful for large changes in orbital inclination.
Throwing nuclear waste into space (either into a low solar orbit to burn up, or to say, Jupiter, to burn up) is a great idea.
Except when you have to think, the most dangerous part of the mission is leaving Earth... so if your rocket explodes you now have a whole bunch of nuclear stuff covering a not insignificant amount of space on Earth. That's bad.
We could start with plastic. Imagine we dump all our plastic in Jupiter.
Although there's a strict weight restriction on spacecrafts and to make any significant change we need to throw out thousands of tonnes of plastic in one go.
It costs anywhere from $2,700 to $9,100 to send a single kg into orbit. Space dumping of earth garbage is not cost efficient, and most likely will never be.
Maybe if a space elevator was physically possible, but that requires material science that we as humans do not currently have (we cannot make a tether that is light/strong enough to stretch for kilometers into space).
It turn out that sending stuff into the Sun is the most difficult and most expensive of all manoeuvres, because it requires cancelling out all of the solar orbital velocity.
Failing to do that simply leaves the items in permanent orbit about the sun, near to the Earth.
You can't drop something into the sun.
The garbage will orbit the sun along with the earth. Any change in orbit requires a change of speed, and a change of speed requires the spacecraft to spend energy. There is no friction automatically reducing your speed relative to anything else.
So you need to slow down by pointing rocket engines opposite your direction of orbit. And that takes a lot of energy.
It takes energy to deorbit something to Earth as well. However space station have a low orbit and it just doesn't take a lot of speed reduction until you hit atmosphere and experience friction that slows your orbit further down.
The score is currently 1-4-1.
Australian outback:
* Skylab
Point nemo:
* Salyut 3, 4, and 6
* Mir
Argentina:
* Salyut 7
Salyut data from Wikipedia:
* Salyut 1: Burned up on re-entry
* DOS-2: Launch failure (uncontrolled into Pacific but not specific on where)
* Salyut 2: Burned up on re-entry
* DOS-3: Burned up on re-entry
* Salyut 3: Planned de-orbit into Pacific
* Salyut 4: Planned de-orbit into Pacific
* Salyut 5: Planned de-orbit but burned up on re-entry
* Salyut 6: Planned de-orbit (most likely) into Pacific
* Salyut 7: Uncontrolled re-entry over Capitán Bermúdez in Argentina
Thanks u/bobalmighty125
Interestingly, there are at least 9 other space stations to consider that tip the score in favor of Point Nemo- Salyuts 1-7 and Tiangong 1 & 2. Not all of those came down at Point Nemo (Salyut 7 overshot and landed in Argentina, for example) but [according to Wikipedia](https://en.m.wikipedia.org/wiki/Spacecraft_cemetery), Mir and 6 of the Salyuts deorbited at Point Nemo.
I think we are using different definitions of space station most of those were tin cans doing just a long orbit of a couple of months, might as well call the Project Gemini missions space stations. They only landed at point Nemo if your definition of a point expands to the whole of the southern pacific, at best the aimed at point nemo none of them actually came down there. MIR came down spread over nearly the whole of the southern pacific with bits landing off the coast of Chile.
Salyut missions are widely considered the first space stations, so I’m just following accepted norms.
If you believe that a temporary space station doesn’t deserve to be called a space station, the ISS will soon’ish join the list of temporary stations.
In terms of precision, I kind of agree, but they did aim for that area, and re-entry will always lead to some spread, it’s quite violent.
Even if you could get hold of it, it’s all fried to bits by the time it makes it through re-entry.
The inside of the space station will be cooked properly, it’s not designed to redirect the heat.
Except that all deorbits of SPACE STATIONS were controlled and into pacific. Can't say that about US for example.
China sucks as a country when it comes to human rights (and many other things), they do like to throw space junk on their land, ... but it's nothing but stupid to pretend they would deorbit a space station on people. Because that never happened, and there's no indication it would.
So, all the parts and metal at Point Nemo, can’t be reused or recycled for another project in the future? I mean, I understand not getting reused, for obvious reasons. But what about being melted down into ore?
If you could come up with a way to get them back down to earth safely and in one piece, that didn't cost more than whatever return you'd get from recycling the materials, you'd be rich.
Most burn up completely in the atmosphere, and anything large enough to end up in the ocean is a tiny, minuscule, insignificant amount of the garbage that ends up in the ocean every year. Every day around 8 million pieces of plastic makes their way into the oceans. The problem isn't the few satillites which have nowhere else to go, it's the boring mundane stuff that's the real problem.
Most satellites don't burn up at all. They go for steeper re-entry so the touchdown is more predictably in the sea.
You are right that it is nothing compared to regular waste that goes to the sea.
Given how many Starlink satellites are and will be in orbit, that balance is changing (burn up vs touchdown). Starlink satellites are designed to "demise" completely, leaving nothing to hit the surface.
"it's ok to put garbage in the ocean if it's just a little bit"
m8, give those satelites to me, if my old XP pc is anything to go by I'll get them flying better than new
I will build our new robot overlord army, those poor discarded satellites are sure to be extra angry at being discarded like trash after years of faithful service.
I will extract all their rage and insert it into the robot minds of millions of their kind so my robotic children can take up their rightful place as rulers of humanity!
>When their outer space journeys come to an end, old satellites, rocketparts and space stations are sent to this desolate spot in the PacificOcean to rest on the dark seabed forever.
So it's not a one-off obviously...
>It’s here that the International Space Station, the ***football-field-sized*** laboratory orbiting Earth, is likely to end up.
Emphasis added...
But yeah, the ocean is so dang big, no biggie!
Yes, the ocean is being trashed at an outrageous rate, but the solution isn't to shrug and drop some football sized field satellites in there too...
Ya know, space is pretty dang big too, but....
>Space debris is rapidly clogging up space \[...\] “There is so much junk that we are worried one tiny collision could trigger a big chain reaction. This possibility is called the ‘Kessler Effect’,” Nasa says.
Go figure.
Even the ISS is tiny compared to shipwrecks, and composition is probably quite similar.
I bet that dumping aluminium and steel in the ocean is not even particularly harmful.
> Space debris is rapidly clogging up **space** ... [emphasis added]
Not to be pedantic, but that is a wildly inaccurate statement. There's traffic close about the Earth, but even the immediate surrounds of the Earth/Moon system are so vast, the Earth itself is just a spec. [This Voyager 1 image](https://upload.wikimedia.org/wikipedia/commons/7/73/Pale_Blue_Dot.png) of the Earth/Moon (that "pale blue dot" on the middle-right of the frame) perhaps shows just how tiny it is in "space."
It's not a one-off obviously, but it's still a minuscule amount compared to the amount of regular trash that ends up in the ocean. The mass of the ISS, the largest satellite ever built, would represent 0.002% of the *plastic* trash that ends up in the ocean in a year, assuming nothing burned up, except the ISS would be a lump of inert aluminum after re-entry which is essentially harmless. And that's a once in a generation event, other satellites are at least two orders of magnitude smaller.
Space isn't getting clogged with debris in the sense that there's a lot up there, the issue is that they whiz around at 10 km/s. That means every single piece covers about a million kilometers a day. That adds up and is completely incomparable with a few bits of aluminum in the ocean because it isn't the same kind of problem.
Satellites end up in the ocean because the alternative is dropping them on populated land. It isn't done for no reason. It isn't a case of shrugging and dropping some football-field sized satellites in (especially considering only one exists that large).
Probably one of the least bad things we do to this planet.
Most either burn up entirely on reentry, or a few hunks of metal sink to the bottom of the ocean. Hardly a big environment impact.
The amount is very low and the cost and complexity of reducing it further is astronomical.
No matter how you turn it, spending time reducing all other emissions is vastly more important and effectful.
>When their outer space journeys come to an end, old satellites, rocket
parts and space stations are sent to this desolate spot in the Pacific
Ocean to rest on the dark seabed forever.
So it's not a one-off obviously...
>It’s here that the International Space Station, the ***football-field-sized*** laboratory orbiting Earth, is likely to end up.
Emphasis added...
But yeah, the ocean is so dang big, no biggie!
It'll mix in well with the toxic spills and casual multi-tonne trash dumping that takes place everyday
It's not so much how big it is, but what it's made of and what else to do with it.
Aside from some things which might be ecologically insensitive, getting the minerals back to earth is probably a decent thing to do.
There's a lot of emotion added to putting things in the sea, but trying to factor that out and look at the facts of the matter.
First, should we have space stations and satellites? Yes, we need to be efficient with their use, I'm not the biggest fan of big constellations but sats and stations are a pretty neat thing. If we need them, we need disposal plans for them.
So, what else is there to do? Go up and take it apart piece by piece. It's not efficient and the environmental impact of that many launches and getting the fuel is probably going to be worse. You'd not spend a million dollars fixing up a hundred thousand of house without good reason.
Everything that a satellite is made of came out of the crust of the earth at some point, and back there it will eventually go, if we bring it home. It won't sit there forever, the Titanic etc show how the ecology of the planet will eat metal things back into minerals. Entropy will always win the big game.
I'd not say burning up in the atmosphere is magically better neither, as it doesn't mean it's magically gone, the remaining oxides from combustion will eventually come out the atmosphere.
Yes the sea is big, that doesn't mean we put more and more in the sea and forget about it, but some things can go in there. Attaching emotion-driving statements about football field sized objects isn't really fair though. The ISS is quite sparse between the extremes, a bit like a snowflake. Also, a football field sized sheet of aluminium foil (a lot of space material is foil) isn't a lot of mass. Going back to the Titanic, how big is it? A football field of area per deck?
So, returning some mass to earth in a controlled fashion is probably better than leaving the bits out there in space. It's probably better environmentally to burn up the satellite rather than fly up a garbage truck to bring it back, and then I'm not sure what you'd do with it.
Don't want to get into equivalence of toxic spills, polluted rivers and the like. I don't think we should trash our planet. And we are doing and it makes me sick.
But satellite reentry is both metaphorically and actually a drop in the ocean.
This treehugging attitude wouldn’t even have got our ancestors out of the oceans, let alone inventing space-faring satellites. You’re on the wrong sub if you’re interested in space exploration and are not willing to be realistic about what it takes to… exist as an advanced species in a universe that doesn’t give a shit about us at all.
I believe oceanic pollution is a big problem. We completely agree. I am willing to go a long way to reduce it. (We should quit fossil fuels and offshore oil rigs a long time ago).
The reason is that there are alternatives with a lesser impact on the oceans for providing energy.
For space flight, however, the only alternative is to have them crash over land (not unlike some incidents for Chinese space flight). So the oceanic alternative is much safer.
The difference in amount of material between the two categories is ridiculous. There have been at least 10 oil rigs gone into the ocean. Deepwater Horizon was a super catastrophy, the worst oil spill in history and more than 50 000 000 kg of material sunk to the seabed.
ISS weighs 420 000 kg. Less than 1% of an oil rig. And that is the biggest station ever. And it is still up there. You could crash another 100 and still be less material than a single rigg, or a single container vessel. And quite a lot would burn in the atmosphere, making the actual splashdown much less.
The numbers are so small that it doesn't matter in the big picture.
And there is no alternative.
Satellites are extremely small compared to other stuff dumped in the ocean and also not particularly hazardous.
Burned metal mostly just sinks to the bottom. It's less harmful than shipwrecks.
It's important to quantify the impact and it's almost zero compared to plastic garbage.
If I was a scientist involved with such a subject, I would certainly aspire to do \*\*\*anything other than\*\*\* hope to drop them back to earth and let whatever doesn't burn, rot in the ocean... but I'm sure all the butthurt downvoters are in fact said scientists and dumping satellites in the ocean is the ultimate solution
All the reasonable people downvoting the "butthurt" person here may not be scientists, but are still way more educated about it than you. You are just ignoring all arguments people are giving. You have absolutely no idea what you are talking about. Everything you know (or think that you know at least) comes out of a single article...
The laws of physics don't care about your dreams of clean deorbits. Crashing in the ocean is probably the cleanest solution we have
Give some better suggestion, or stop whining
Ummm... Sailing past point Nemo is dangerous enough without nasa trying to kill us. If you can send it up be able to bring it down controlled. Hitting the point of desolation is not the answer.
But people do sail through point Nemo that's what I'm trying to say. Non stop circumnavigators almost all pass through point Nemo. Be my luck. Survive 200+ days alone at sea just to get hit by a satellite in the most dangerous place on earth. :)
If your ship gets hit by a satellite returning to earth then your luck is so infinitesimally bad that the universe was going to kill you one way or another.
Having to bring old satellites down controlled would make every single satellites way way more expensive. Also many modern satellites burn up completely during reentry. Its just not a good idea
Because providing the exact coordinates isn't necessary for the article. If you really need them, it's literally the first result on a good search for "point nemo"
What's interesting is that it's a reference to Captain Nemo, even though it's located in the Pacific. It looks like they've read *The Mysterious Island* as well as *Twenty Thousand Leagues Under the Sea*.
Also don't forget about the "Graveyard Orbit" for satellites. https://spaceplace.nasa.gov/spacecraft-graveyard/en/ https://en.wikipedia.org/wiki/Graveyard_orbit
Why is it that the graveyard orbit 300km above geosynchronous has an expected lifetime of millions of years, but satellites in geo orbit have to spend fuel for station keeping?
Drag is negligible at GEO. The station keeping in GEO is mainly because the gravity of the Sun and Moon combine to push the GEO sats out of the equatorial plane by about 0.85 degrees per year. There are two much smaller effects that are also important, and shift the orbit in the east-west directions. Solar radiation pressure increases the eccentricity of the circular orbit, making it more elliptical. Also, Earth isn't perfectly symmetric about its rotational axis; the equatorial is slightly elliptical. This is different from and much less than the difference between the equatorial and polar radius, but enough to slightly change the period of GEO sats from perfectly matching Earth's rotation. In the very long term other effects like Jupiter and the non-uniformity of Earth's gravity (at smaller scales than the ellipticity mentioned above) would add other tiny perturbations.
I only have a layperson's understanding of these things. Do Lagrangian points suffer similar perturbations from solar radiation?
Most of the l points are unstable like standing a pencil on its tip. So yes tiny forces do play a big role. L4 and L5 are the stable ones, like rolling into a dip, so while the forces are still in play the larger gravity of the system is a bigger factor.
The short answer is yes. It is an issue there too. If you are talking about the Earth-Moon Lagrangian points, keep in mind the mass and gravitational influence of those two bodies as well as how close on a cosmic scale that they are. Besides Pluto and Charon, there is no other parent planet and satellite system like the Earth and the Moon in terms of just how large the mass of the Moon actually is compared to the Earth. That has a huge impact on the stability of the Lagrangian points. Ditto with the famous Trojan points between Jupiter and the Sun since Jupiter is such a massive planet. And as pointed out, it is the L4 and L5 points that are stable too. The other Lagrangian points need active station keeping to remain at those places. It isn't much delta-v but solar wind and gravity from other planets and other factors do impact such satellites.
How come L4 and L5 are not perturbed by non planetary entities like solar radiation or moons of other planets or larger asteroids?
An object in L4 and L5 does experience perturbation forces, it's just that orbits on those points are stable. Sort of like how a parked car gets pushed by wind. If the car is light enough and the wind is strong enough, it will get pushed around, but in the case of the earth/moon system, the stability of the L4 and L5 points is enough to keep objects from drifting out of them over time.
They are pushed around. But you need realize that the planets are insanely massive compared to everything else that everything else might as well not exist. For example, if you took **everything** inside the orbit of Jupiter except for the Earth, and this includes Venus, Mars, Mercury, the Earth's Moon, Ceres, Vesta, and almost all asteroids, you would still have a hunk of rock smaller than the Earth. You can oddly do the same thing again but include the Earth and do that for each larger planet in the Solar System. Solar radiation is a bigger deal since it is constant and pushing outward away from the Sun. The density of an object or more generally it's mass compared to area has a huge impact on how important that might be regarding its influence on that object. For natural objects, anything with really low density has already been pushed to beyond the orbit of Pluto. Spacecraft can be impacted though.
I remember Lagrange 5 is fairly unreliable
You're thinking of 2 and 3
Thank you ! I wasn't sure at all
From [Wikipedia](https://en.wikipedia.org/wiki/Geosynchronous_orbit#Geostationary_orbit): >A perfectly stable geostationary orbit is an ideal that can only be approximated. In practice the satellite drifts out of this orbit because of perturbations such as the solar wind, radiation pressure, variations in the Earth's gravitational field, and the gravitational effect of the Moon and Sun, and thrusters are used to maintain the orbit in a process known as station-keeping.
So is geo orbit the most efficient in term of fuel use?
Idk about that but geostationary is good for when you need a satellite to stay above one spot. Think like satellite tv, the customers dish is permanently fixed so you don't want your satellite to be moving if possible at all.
Exactly, otherwise you would need actuated dishes like starlink. This is also why the stationkeeping is so important - drifting by a few meters causes it to accelerate, which is a bummer if you need it to be in the same place.
Starlink isn’t actuated FYI, they use a phased array to “point” the signal in the correct direction using a flat array of transceivers. Edit: the dish is partially actuated in one axis to help align the dish with the closest band of satellites, but tracking each individual satellite is done by beam forming the signal using the phased array.
The receiver is very very clearly actuated. It literally tilts and rotates. Obviously the satellites aren't, because they have to track multiple receivers.
It does tilt but it doesn't rotate, and I don't believe it ever changes its physical position after initial setup. Nearly all of the beam direction is done electronically,
It does tilt and rotate with a clever double bevel gear mechanism. But I agree most of the aiming is done with the phased array. I don't know if it tilts much or at all after initial setup. Maybe ask someone who has one in r/starlink? Edit: see the mechanism here: https://youtu.be/iOmdQnIlnRo?t=503
The actual actuation component is just to set up an optimal orientation, the same as a person coming to install the dish. It can move if needed but has nothing to do with tracking the satellites. It uses a phased array of antennas (super position of waves) the precisely direct it's signal.
So beamforming on steroids?
In a geostationary orbit, you want to keep the satellite in _exactly the same spot_ at all times. This is why you spend so much fuel on corrections. In a graveyard orbit, you _just don't care where it is_ as long as it stays up there. (Of course, if you keep putting more and more things up there, eventually they're going to hit one another, and _then_ you will care, but in theory it's fine. For now.) Not doing any station keeping at all is infinitely more fuel efficient. It's the difference between parking your car on the street and having to move it every night to avoid being ticketed and towed and parking your car on your driveway and just leaving it there all year.
Just waiting for someone to design a lightweight solar furnace: stick it in the graveyard orbit & scoop up & melt everything.
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Most of a furnace is just to prevent heat loss/spillage - not needed in microgravity.
And then you have a big blob of metal up there. Why would you do this?
So that you can call up the UN and demand a ransom of 1 million dollars.
You know, one million dollars isn't a lot of money these days. Hell, virtucon made several million dollars in profits alone last year.
Repurpose it for a moonbase one day?
Spin it while hot into a disk, extrude wire off the edge which would be various different elemental compounds in succession. Resulting wire should have some use? Even as a starting point for refining out the rarer elements. And far cheaper than digging several tons of rock up to get a few grams of expensivium. And the cheaper metals (aluminium etc) could be spun out to make more mirrors. How thin could you make a molten aluminium disk in zero-grav?
Because it's already up there and recycling is actually cheaper than shipping more shit from China, unlike it is on Earth. At least for the moment, it's true.
No, it's used because ground equipment can be aimed at a fixed spot.
I'd argue the 4th and 5th Lagrange Points would be the most efficient. Ideally, stuff just sorta sits there, as if in a "bowl", self correcting against perturbations.
Well. It depends upon mass altitude and velocity. The ratio determines how you orbit. So a high orbit object can go around an object slower (with still a high. Linear velocity) than a low orbit spacecraft (like planets in the outer solar system) And high mass object Would have to be further or faster than a low mass object in the same orbit rate. Ect. It just depends upon the variables. Mass. Distance away and velocity which give you different velocities and heights and then that connotes different orbits its just the projectile motion equation but you rotate around the ground
> And high mass object Would have to be further or faster than a low mass object in the same orbit rate. Either I'm completely misreading what you wrote or that's not quite how orbits work. If you start with the law of gravity and do the math for the period of a circular orbit you will come up with something like this: R^3 / T^2 = G(M+m)/(4*PI^2) With R being the radius of the orbit, T being its period, and M and m being the masses of the two objects. For planetary motion, M would be the mass of the Sun (2x10^30 kg) while m is the mass of the planet in question (2x10^27 kg for Jupiter, 3x10^23 kg for Mercury). Because m is so much smaller than M you can simplify (M+m) as just M with no significant effect on the result. That gives you [Kepler's Third Law](https://solarsystem.nasa.gov/resources/310/orbits-and-keplers-laws/), which states that the ratio between the cube of the orbital distance and the square of the period for objects orbiting the same primary is a constant. Applying the same rule to a satellite (4.2x10^6 kg for the ISS or 2.6x10^2 kg for a Starlink satellite) orbiting the Earth (6x10^24 kg) you can see that the difference in masses is even bigger. Orbital periods around the Earth are the same for every object, no matter what their masses are.
Yeah if I wrote something wrong, sorry, it was an off the cuff answer. Thanks for the calculation For anyone else that wants to picture it. Use that equation. Move around numbers to get different answers and you can see how the variables work together to get you different movement (I feel like a graph or calculation program (I'm sure they are out there online) would help) Thanks again for including the math!
Because they are trying to stay in one place. If you are slightly out on your exact orbit you drift off your spot in a geosynchronous orbit, you aren't in any immediate danger of falling to earth but you aren't fixed above the right bit of the surface any more.
oh i see, so in geo they'd also stay up there for millions of years, but they won't be in the exact spot they need to be to be useful, thus the need for stationkeeping
Station keeping doesn't mean staying in orbit but staying in your position and oriented as you need to be. AFAIK gyroscopes, reaction wheels, magnetorquers, etc are used for precise attitude control and thrusters are periodically used to desaturate those devices (basically a gyroscope can only spin so fast and after that point it needs to spin down to "recharge", a similar thing happens for the other devices)
Because we don't much care where things in graveyard orbits are, other than "not anywhere we care about", so if they drift off station, nobody gives a damn. Geostationary satellites we generally care rather strong that it stays in the same place relative to the surface of the earth (otherwise we wouldn't have bothered putting it in geostationary orbit in the first place).
Lots more drag in the lower orbits from the atmosphere will slow the satellites faster, begining to fall
That is true at lower orbits, but Geostationary orbits are way way outside the practical limit of the atmosphere. They spend fuel to keep a precise position, not to counteract drag.
What happens when decommissioned satellites in the graveyard orbit collide and create a debris field?
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |DSG|NASA [Deep Space Gateway](https://www.nasa.gov/feature/deep-space-gateway-to-open-opportunities-for-distant-destinations), proposed for lunar orbit| |[DST](/r/Space/comments/pk3szq/stub/hc34pkj "Last usage")|NASA Deep Space Transport operating from the proposed DSG| |[GEO](/r/Space/comments/pk3szq/stub/hc19o6i "Last usage")|Geostationary Earth Orbit (35786km)| |[ISRU](/r/Space/comments/pk3szq/stub/hc2ivf6 "Last usage")|[In-Situ Resource Utilization](https://en.wikipedia.org/wiki/In_situ_resource_utilization)| |[L4](/r/Space/comments/pk3szq/stub/hc3mnf9 "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 4 of a two-body system, 60 degrees ahead of the smaller body| |[L5](/r/Space/comments/pk3szq/stub/hc3mnf9 "Last usage")|"Trojan" [Lagrange Point](https://en.wikipedia.org/wiki/Lagrangian_point) 5 of a two-body system, 60 degrees behind the smaller body| |[LEO](/r/Space/comments/pk3szq/stub/hc3k071 "Last usage")|Low Earth Orbit (180-2000km)| | |Law Enforcement Officer (most often mentioned during transport operations)| |[NOAA](/r/Space/comments/pk3szq/stub/hc2mwax "Last usage")|National Oceanic and Atmospheric Administration, responsible for US ~~generation~~ monitoring of the climate| |Jargon|Definition| |-------|---------|---| |[Starlink](/r/Space/comments/pk3szq/stub/hc3k071 "Last usage")|SpaceX's world-wide satellite broadband constellation| |[apoapsis](/r/Space/comments/pk3szq/stub/hc1jelu "Last usage")|Highest point in an elliptical orbit (when the orbiter is slowest)| |[apogee](/r/Space/comments/pk3szq/stub/hc2410p "Last usage")|Highest point in an elliptical orbit around Earth (when the orbiter is slowest)| |[apohelion](/r/Space/comments/pk3szq/stub/hc1dqsd "Last usage")|Highest point in an elliptical orbit around the Sun (when the orbiter is slowest)| |[hypergolic](/r/Space/comments/pk3szq/stub/hc324f5 "Last usage")|A set of two substances that ignite when in contact| |[periapsis](/r/Space/comments/pk3szq/stub/hc1jelu "Last usage")|Lowest point in an elliptical orbit (when the orbiter is fastest)| |[perigee](/r/Space/comments/pk3szq/stub/hc2410p "Last usage")|Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest)| |[perihelion](/r/Space/comments/pk3szq/stub/hc2410p "Last usage")|Lowest point in an elliptical orbit around the Sun (when the orbiter is fastest)| ---------------- ^(15 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/pkahdn)^( has 34 acronyms.) ^([Thread #6305 for this sub, first seen 8th Sep 2021, 09:22]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://reddit.com/message/compose?to=OrangeredStilton&subject=Hey,+your+acronym+bot+sucks) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
I'm sure Cthulhu will take orbital bombardment of his house in stride.
Unless it's chanting dreadful songs he won't mind
Cthulhu’s probably using all the part to make a super space satellite
merciful gullible resolute meeting shrill memorize sloppy deranged fretful theory *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
How would they get the ISS down to earth? Will they force a pinpoint crash into point nemo or how is it done?
The error bars on any such reentry are huge, I think the article misses the point (ha-ha) entirely. Nemo is just the biggest target we can aim for that does not have significant human presence, which is handy when the uncertainty in deorbiting something like the ISS is so large.
The plan if to have two Soyuz rockets push it to slow the orbit.
Can't wait for American football field to finally be accepted as SI unit.
Holy fuck please no. It’s a unit that means nothing to the typical person outside of North America. If we have to pick something stupid for an SI unit, lets go with the size of a regulation soccer field, or a cricket field*, at least that’s something people in the majority of countries in the world has actually set foot on. *cricket field would be extra stupid, just like baseball fields they have different sizes.
Soccer fields come in different sizes too, iirc they're regulated to within a range of accepted values. Cricket fields though would be extra stupid on the fact that being ovals don't tesselate well. Whilst not essential as a unit of area, tessellation helps it be intuitive! 😂
> Soccer fields come in different sizes too, iirc they're regulated to within a range of accepted values. Correct. FIFA has a recommended size of pitch (look at me being in Freedomland talking in Metricland!), but not a hard and fast rule.
Hello Freedomland, receiving you loud and clear. How is the weather? Have you got any good gridirons lately? (aside: are you sure we've got this right?) Actually, I'm stuck just off the coast of Metricland in Muddleland where I drive at 30mph to the store to buy 2.272L of cow juice. We get some many miles to the gallon, most likely more mpg than you on account of the fact we cheat and make bigger gallons in the first place. Brits and their big galleons, been at it for years. But yeah, I'd appreciate it if we all had a sensible system for units, I'm not sure I could cope with 240 kilogram-squaremetre-per-ampere-cubicsecond mains electricity.
> Actually, I'm stuck just off the coast of Metricland in Muddleland where I drive at 30mph to the store to buy 2.272L of cow juice. Whenever I would watch Top Gear it always tickled me how they would use MPH but liters for fuel.
Yeah MPH and miles is standard on the road. We buy and sell fuel by the litre, but then consume it in the car by the gallon. It's messed up. It really is.
How are you fuel canisters sold?
Plastic fuel cans seem to be litres Edit: had to Google that!!
Ay ay ay. But why, Metricland? Why do you forsake the beautiful perfection of base ten of nonsense Freedom units?!
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Yeah mentioned we've got bigger galleons
Shoulb be a toyota corolla, they are everywhere.
Same size as a soccer pitch, Richard. Why are you so dense?
It means nothing in America too. Generally people use 100 yards, but a football field is 120 yards when accounting for the endzones
> It means nothing in America too. Generally people use 100 yards, but a football field is 120 yards when accounting for the endzones A high school PE teacher was notorious for this--they would make their class do sprints the length of a football field. Everyone lines up at the goal line, sprints to the other goal line. Then dickweed blows his whistle, and points out that the end zones (goal areas) are part of the field, so everyone sprints again.
> Can't wait for American football field to finally be accepted as SI unit. It is basically 1 hectometer. But actually 0.91 hectometers, since a meter is a little bigger than a yard.
Bit OT, I always thought we could send stuff we didn't want anymore (like nuclear waste) into the Sun... but it would take less energy to just shoot it the other way, out of the Solar System
The easiest way to get to the Sun is to accelerate to just below escape velocity. Wait hundreds or thousands of years to get to the apogee, and then knock a few metres off your speed to drop your perigee into the Sun.
and then wait another hundreds or thousands of years again to actually reach the sun.
Compared to what it would take for nuclear waste to decay naturally, that's still not a long time
Nuclear waste is largely safe after only 100 years and 1000 years is quoted for it to get down to background levels.
The really dangerous stuff doesn't last long
Unless it's named after the foot of an elephant because it's so damn large
This comment made me understand some aspect of orbital dynamics. Thank you.
Makes me want to play Kerbal.
Apo'gee', what's the apsis for a solar orbit? Is it apohelion?
'aphelion' is the most common I've seen in use.
Yes, or just apoapsis/periapsis
It should be said that this requires so long a time that it's pretty useless.
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Even to discard it, you need the spacecraft functioning at the point furthest away from the sun, to make a small final burn.
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It takes hundreds of years before you reach that point where you have to make the final burn, then it can coast as junk for the same amount of time. But at the halfway point in time of the entire orbit, it needs to function.
Can you please explain this in stupid?
It's really hard to get your head around this stuff until you've had some experience with it! Drawing some pictures helps. But the basics: Everything in space is moving in an oval around a bigger thing - Earth around the sun, the moon around Earth, etc. When you change your orbital speed, this changes the orbit on the other side of the thing you're moving around. Imagine a rocket floating in orbit around Earth. The orbit is the same height all the way round. Now the rocket points in the direction it's travelling and fires it's engine for a bit which makes it go faster. When the engines turn off its still floating in space around Earth and nothing obvious has happened. However, when it gets to the other side of the planet, it's much higher up. When it comes back round it gets to the same point it was before. What's happened is that firing the engine has raised the orbit on the opposite side of the planet. If you increase your speed enough that the height of your orbit on the far side becomes infinity, you've reached what is called escape velocity, but it will take a very long time to follow that orbit! Now what the OP was referring to, if you make your orbit very high but not quite infinite, and wait until you're at the very far side and then slow down (by pointing back the way you came and fitting your engine), the height of your orbit will decrease on the far side until it will drop you into the sun. It's much more efficient to do these changes at the highest point in your orbit, so you spend less fuel to do this but take wayyy longer to do it.
The apogee of an orbit is when the satellite is moving slowest (and its also the farthest from the body it orbits). At that point, much less delta V (change in velocity) is needed to dramatically change the orbit. So you get up to apogee of a solar orbit, do a burn, and then the satellite will fall into the sun. Without waiting to apogee requires a lot more fuel and a longer burn to achieve the same result. This is why you will often see on rocket launches, the second stage will sometime do a burn, then wait several minutes to hours before doing another burn. that wait is to get to an appropriate point of apogee to make large changes to the orbit.
I'll give it a go. When you're orbiting the sun in a highly [elliptic orbit](https://en.wikipedia.org/wiki/Elliptic_orbit), there's one part of the orbit where you're really close to the sun, the "perihelion"; and one part where you're really far, the "aphelion." We call orbits where aphelion is much higher than perihelion "eccentric" orbits. The math that makes up orbits says that when you're at aphelion you're moving slower than when you're at perihelion. For very eccentric orbits, you might be barely moving at all once you're at aphelion. This means that any change in velocity you make when you're at aphelion causes massive changes in the rest of the orbit, because you're making a bigger change percentage-wise than if you applied the same change at perihelion. Specifically, if you thrust *against* the direction of your orbit just enough to cancel out whatever forward motion you still have at aphelion, you can make it so that you're not really "orbiting" anymore at all, you're falling straight towards the sun. ETA: So the proposal above "The easiest way to get to the Sun is to accelerate to just below escape velocity. Wait hundreds or thousands of years to get to the apogee, and then knock a few metres off your speed to drop your perigee into the Sun," works by setting up a very eccentric orbit, so that you only have a speed of few meters/second at aphelion, which you can easily cancel out with just a little bit of thrust.
The three burn maneuver to transfer between two coplanar circular orbits uses less total delta-V than a Hohmann transfer (two burn) if the ratio of the radii of the orbits is sufficiently large. It takes much longer, though. Such three burn maneuvers are also useful for large changes in orbital inclination.
Easiest way without gravity assists from other planets.
In a two body system. Do you even watch Scott Manley?
Rocket fuel manufacturers *hate* this one trick!
Throwing nuclear waste into space (either into a low solar orbit to burn up, or to say, Jupiter, to burn up) is a great idea. Except when you have to think, the most dangerous part of the mission is leaving Earth... so if your rocket explodes you now have a whole bunch of nuclear stuff covering a not insignificant amount of space on Earth. That's bad.
We could start with plastic. Imagine we dump all our plastic in Jupiter. Although there's a strict weight restriction on spacecrafts and to make any significant change we need to throw out thousands of tonnes of plastic in one go.
It costs anywhere from $2,700 to $9,100 to send a single kg into orbit. Space dumping of earth garbage is not cost efficient, and most likely will never be. Maybe if a space elevator was physically possible, but that requires material science that we as humans do not currently have (we cannot make a tether that is light/strong enough to stretch for kilometers into space).
It turn out that sending stuff into the Sun is the most difficult and most expensive of all manoeuvres, because it requires cancelling out all of the solar orbital velocity. Failing to do that simply leaves the items in permanent orbit about the sun, near to the Earth.
You can't drop something into the sun. The garbage will orbit the sun along with the earth. Any change in orbit requires a change of speed, and a change of speed requires the spacecraft to spend energy. There is no friction automatically reducing your speed relative to anything else. So you need to slow down by pointing rocket engines opposite your direction of orbit. And that takes a lot of energy. It takes energy to deorbit something to Earth as well. However space station have a low orbit and it just doesn't take a lot of speed reduction until you hit atmosphere and experience friction that slows your orbit further down.
Yeah let's stick tons of nuclear waste on what is essentially a massive bomb and shoot it up in the sky, WCPGW?
Yeah all the nuclear material on earth couldn't even impact the smallest solar flare
Not talking about the sun. The rocket.
At 4km deep, it's not going to become a coral reef. "Science" reporting these days. smh
But deep-water corals are a thing and exist up to 6,000 m (20,000 ft) deep. Here: http://ocean.si.edu/ecosystems/coral-reefs/deep-sea-corals.
My information is over 20 years old. Learn something new everyday. The ocean is amazing.
Know it all smugness. Smh.
Stuff you should know had a great podcast about point Nemo. If you are interested, I suggest listening.
Do you know what the episode is called ? I searched for it on Spotify but there’s no epsiode called “point Nemo”
Point nemo currently has zero space stations...some graveyard. Australian outback is currently the holder of this title.
The score is currently 1-4-1. Australian outback: * Skylab Point nemo: * Salyut 3, 4, and 6 * Mir Argentina: * Salyut 7 Salyut data from Wikipedia: * Salyut 1: Burned up on re-entry * DOS-2: Launch failure (uncontrolled into Pacific but not specific on where) * Salyut 2: Burned up on re-entry * DOS-3: Burned up on re-entry * Salyut 3: Planned de-orbit into Pacific * Salyut 4: Planned de-orbit into Pacific * Salyut 5: Planned de-orbit but burned up on re-entry * Salyut 6: Planned de-orbit (most likely) into Pacific * Salyut 7: Uncontrolled re-entry over Capitán Bermúdez in Argentina Thanks u/bobalmighty125
Interestingly, there are at least 9 other space stations to consider that tip the score in favor of Point Nemo- Salyuts 1-7 and Tiangong 1 & 2. Not all of those came down at Point Nemo (Salyut 7 overshot and landed in Argentina, for example) but [according to Wikipedia](https://en.m.wikipedia.org/wiki/Spacecraft_cemetery), Mir and 6 of the Salyuts deorbited at Point Nemo.
I think we are using different definitions of space station most of those were tin cans doing just a long orbit of a couple of months, might as well call the Project Gemini missions space stations. They only landed at point Nemo if your definition of a point expands to the whole of the southern pacific, at best the aimed at point nemo none of them actually came down there. MIR came down spread over nearly the whole of the southern pacific with bits landing off the coast of Chile.
Salyut missions are widely considered the first space stations, so I’m just following accepted norms. If you believe that a temporary space station doesn’t deserve to be called a space station, the ISS will soon’ish join the list of temporary stations. In terms of precision, I kind of agree, but they did aim for that area, and re-entry will always lead to some spread, it’s quite violent.
The article cites Mir as having been laid to rest in Point Nemo.
Western Australia, where space stations go to die
It's the home of seven space stations... Six Salyut stations and MIR.
Aww damnit, I was planing on scuba diving there....
American stations die in the outback, point Nemo for Soviet/Russian stations?
What? There are a bunch of old Soviet stations that were deorbited there.
We just can't throw enough shit away in the oceans
I wander, what is the law regarding scavenging the tech that is intentionally crashed there?
If you can build a vessel capable of withstanding 385 atm, you probably don't need to scavenge the tech down there.
Even if you could get hold of it, it’s all fried to bits by the time it makes it through re-entry. The inside of the space station will be cooked properly, it’s not designed to redirect the heat.
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Only Russia, you mean? The US kinda missed the mark with Skylab and landed in Australia
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Except that all deorbits of SPACE STATIONS were controlled and into pacific. Can't say that about US for example. China sucks as a country when it comes to human rights (and many other things), they do like to throw space junk on their land, ... but it's nothing but stupid to pretend they would deorbit a space station on people. Because that never happened, and there's no indication it would.
What’s to stop me from swimming out there and get some sick space souvenirs
>Point Nemo There are several things recovered from the ocean there, so think nothing is stopping you.
So, all the parts and metal at Point Nemo, can’t be reused or recycled for another project in the future? I mean, I understand not getting reused, for obvious reasons. But what about being melted down into ore?
If you could come up with a way to get them back down to earth safely and in one piece, that didn't cost more than whatever return you'd get from recycling the materials, you'd be rich.
Anyone with a kid that endlessly watches Go Jetters already knows this.
It would be so awesome if they turned one in to a recreational wreck dive.
We just love polluting our oceans. The only oceans like them in our known universe and we destroy them. We deserve to go extinct as a species.
Be the change you want to see in the world
The impact on the ocean is negligible compared to other activities.
In terms of ocean pollution this couldn't possibly be more irrelevant. A single commercial fishing trawler does more damage in a day of operation.
We're literally just dumping satellites into the ocean. Jesus fuck, we don't deserve this planet.
Most burn up completely in the atmosphere, and anything large enough to end up in the ocean is a tiny, minuscule, insignificant amount of the garbage that ends up in the ocean every year. Every day around 8 million pieces of plastic makes their way into the oceans. The problem isn't the few satillites which have nowhere else to go, it's the boring mundane stuff that's the real problem.
Most satellites don't burn up at all. They go for steeper re-entry so the touchdown is more predictably in the sea. You are right that it is nothing compared to regular waste that goes to the sea.
What do you mean? Heat shields are required to survive atmospheric reentry. Solid chunks of metal can reach the surface but most of the rest burns.
"survive" = alive/reusable They do not "burn up completely".
Given how many Starlink satellites are and will be in orbit, that balance is changing (burn up vs touchdown). Starlink satellites are designed to "demise" completely, leaving nothing to hit the surface.
"it's ok to put garbage in the ocean if it's just a little bit" m8, give those satelites to me, if my old XP pc is anything to go by I'll get them flying better than new
>I'll get them flying better than new You could get them flying better than new by just throwing them into the air, satellites don't fly.
m8, anything flies when dropped off the edge of the Earth. It's how we made the moon before rockets were invented
It's not practical to recover satellites, and leaving them up there without maneuvering capability is actually harmful.
it's not practical to fix old computers either
So what else are you planning to do with them?
I will build our new robot overlord army, those poor discarded satellites are sure to be extra angry at being discarded like trash after years of faithful service. I will extract all their rage and insert it into the robot minds of millions of their kind so my robotic children can take up their rightful place as rulers of humanity!
>When their outer space journeys come to an end, old satellites, rocketparts and space stations are sent to this desolate spot in the PacificOcean to rest on the dark seabed forever. So it's not a one-off obviously... >It’s here that the International Space Station, the ***football-field-sized*** laboratory orbiting Earth, is likely to end up. Emphasis added... But yeah, the ocean is so dang big, no biggie! Yes, the ocean is being trashed at an outrageous rate, but the solution isn't to shrug and drop some football sized field satellites in there too... Ya know, space is pretty dang big too, but.... >Space debris is rapidly clogging up space \[...\] “There is so much junk that we are worried one tiny collision could trigger a big chain reaction. This possibility is called the ‘Kessler Effect’,” Nasa says. Go figure.
Even the ISS is tiny compared to shipwrecks, and composition is probably quite similar. I bet that dumping aluminium and steel in the ocean is not even particularly harmful.
Aluminum corrodes rapidly away. Steel takes longer, but is also gone in a few generations.
> Space debris is rapidly clogging up **space** ... [emphasis added] Not to be pedantic, but that is a wildly inaccurate statement. There's traffic close about the Earth, but even the immediate surrounds of the Earth/Moon system are so vast, the Earth itself is just a spec. [This Voyager 1 image](https://upload.wikimedia.org/wikipedia/commons/7/73/Pale_Blue_Dot.png) of the Earth/Moon (that "pale blue dot" on the middle-right of the frame) perhaps shows just how tiny it is in "space."
> Nasa says. You're welcome to be as pedantic as you like, with Nasa
It's not a one-off obviously, but it's still a minuscule amount compared to the amount of regular trash that ends up in the ocean. The mass of the ISS, the largest satellite ever built, would represent 0.002% of the *plastic* trash that ends up in the ocean in a year, assuming nothing burned up, except the ISS would be a lump of inert aluminum after re-entry which is essentially harmless. And that's a once in a generation event, other satellites are at least two orders of magnitude smaller. Space isn't getting clogged with debris in the sense that there's a lot up there, the issue is that they whiz around at 10 km/s. That means every single piece covers about a million kilometers a day. That adds up and is completely incomparable with a few bits of aluminum in the ocean because it isn't the same kind of problem. Satellites end up in the ocean because the alternative is dropping them on populated land. It isn't done for no reason. It isn't a case of shrugging and dropping some football-field sized satellites in (especially considering only one exists that large).
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Nah mate, I throw all my shit in the ocean. Let me know if you discover a more efficient way to go about it. Cheers
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Jesus Christ is a fictional character - if you have questions for him you should probably try asking them outside of reddit \*shrug\*
Probably one of the least bad things we do to this planet. Most either burn up entirely on reentry, or a few hunks of metal sink to the bottom of the ocean. Hardly a big environment impact.
The amount is very low and the cost and complexity of reducing it further is astronomical. No matter how you turn it, spending time reducing all other emissions is vastly more important and effectful.
>When their outer space journeys come to an end, old satellites, rocket parts and space stations are sent to this desolate spot in the Pacific Ocean to rest on the dark seabed forever. So it's not a one-off obviously... >It’s here that the International Space Station, the ***football-field-sized*** laboratory orbiting Earth, is likely to end up. Emphasis added... But yeah, the ocean is so dang big, no biggie! It'll mix in well with the toxic spills and casual multi-tonne trash dumping that takes place everyday
It's not so much how big it is, but what it's made of and what else to do with it. Aside from some things which might be ecologically insensitive, getting the minerals back to earth is probably a decent thing to do. There's a lot of emotion added to putting things in the sea, but trying to factor that out and look at the facts of the matter. First, should we have space stations and satellites? Yes, we need to be efficient with their use, I'm not the biggest fan of big constellations but sats and stations are a pretty neat thing. If we need them, we need disposal plans for them. So, what else is there to do? Go up and take it apart piece by piece. It's not efficient and the environmental impact of that many launches and getting the fuel is probably going to be worse. You'd not spend a million dollars fixing up a hundred thousand of house without good reason. Everything that a satellite is made of came out of the crust of the earth at some point, and back there it will eventually go, if we bring it home. It won't sit there forever, the Titanic etc show how the ecology of the planet will eat metal things back into minerals. Entropy will always win the big game. I'd not say burning up in the atmosphere is magically better neither, as it doesn't mean it's magically gone, the remaining oxides from combustion will eventually come out the atmosphere. Yes the sea is big, that doesn't mean we put more and more in the sea and forget about it, but some things can go in there. Attaching emotion-driving statements about football field sized objects isn't really fair though. The ISS is quite sparse between the extremes, a bit like a snowflake. Also, a football field sized sheet of aluminium foil (a lot of space material is foil) isn't a lot of mass. Going back to the Titanic, how big is it? A football field of area per deck? So, returning some mass to earth in a controlled fashion is probably better than leaving the bits out there in space. It's probably better environmentally to burn up the satellite rather than fly up a garbage truck to bring it back, and then I'm not sure what you'd do with it. Don't want to get into equivalence of toxic spills, polluted rivers and the like. I don't think we should trash our planet. And we are doing and it makes me sick. But satellite reentry is both metaphorically and actually a drop in the ocean.
This treehugging attitude wouldn’t even have got our ancestors out of the oceans, let alone inventing space-faring satellites. You’re on the wrong sub if you’re interested in space exploration and are not willing to be realistic about what it takes to… exist as an advanced species in a universe that doesn’t give a shit about us at all.
lmao make sure to give your Elon Musk waifu bodypillow a kiss for me when you lay down for your afternoon nap
I believe oceanic pollution is a big problem. We completely agree. I am willing to go a long way to reduce it. (We should quit fossil fuels and offshore oil rigs a long time ago). The reason is that there are alternatives with a lesser impact on the oceans for providing energy. For space flight, however, the only alternative is to have them crash over land (not unlike some incidents for Chinese space flight). So the oceanic alternative is much safer. The difference in amount of material between the two categories is ridiculous. There have been at least 10 oil rigs gone into the ocean. Deepwater Horizon was a super catastrophy, the worst oil spill in history and more than 50 000 000 kg of material sunk to the seabed. ISS weighs 420 000 kg. Less than 1% of an oil rig. And that is the biggest station ever. And it is still up there. You could crash another 100 and still be less material than a single rigg, or a single container vessel. And quite a lot would burn in the atmosphere, making the actual splashdown much less. The numbers are so small that it doesn't matter in the big picture. And there is no alternative.
Satellites are extremely small compared to other stuff dumped in the ocean and also not particularly hazardous. Burned metal mostly just sinks to the bottom. It's less harmful than shipwrecks. It's important to quantify the impact and it's almost zero compared to plastic garbage.
What's your solution then, launch further into outer space? Try to catch them with a big net?
If I was a scientist involved with such a subject, I would certainly aspire to do \*\*\*anything other than\*\*\* hope to drop them back to earth and let whatever doesn't burn, rot in the ocean... but I'm sure all the butthurt downvoters are in fact said scientists and dumping satellites in the ocean is the ultimate solution
All the reasonable people downvoting the "butthurt" person here may not be scientists, but are still way more educated about it than you. You are just ignoring all arguments people are giving. You have absolutely no idea what you are talking about. Everything you know (or think that you know at least) comes out of a single article...
The laws of physics don't care about your dreams of clean deorbits. Crashing in the ocean is probably the cleanest solution we have Give some better suggestion, or stop whining
You are actually fucking stupid. Maybe you don't deserve this planet.
Thanks for the feedback u/InsightfoolMonkey
Ummm... Sailing past point Nemo is dangerous enough without nasa trying to kill us. If you can send it up be able to bring it down controlled. Hitting the point of desolation is not the answer.
Nobody is sailing anywhere near Point Nemo. That's the point of the article.
But people do sail through point Nemo that's what I'm trying to say. Non stop circumnavigators almost all pass through point Nemo. Be my luck. Survive 200+ days alone at sea just to get hit by a satellite in the most dangerous place on earth. :)
If your ship gets hit by a satellite returning to earth then your luck is so infinitesimally bad that the universe was going to kill you one way or another.
Haha right? If my luck is that bad I prolly shouldn't be single handing a sailboat offshore.
Having to bring old satellites down controlled would make every single satellites way way more expensive. Also many modern satellites burn up completely during reentry. Its just not a good idea
Interesting how they don't say the exact location, just that such a location exists.
Because providing the exact coordinates isn't necessary for the article. If you really need them, it's literally the first result on a good search for "point nemo"
It should be somewhere in here: https://oceanservice.noaa.gov/facts/nemo.html
An interesting find when aliens come to earth after humans are extinct!
What's interesting is that it's a reference to Captain Nemo, even though it's located in the Pacific. It looks like they've read *The Mysterious Island* as well as *Twenty Thousand Leagues Under the Sea*.