And what is the concern around tracking them, inability to divert a spacecraft or satellite that might collide with a swarm of small objects?
Just like the movie Gravity, if there was an explosion in space and you had a lot of small objects floating around in a cloud you can't detect, that could snowball into destroying more things in orbit, making the problem even worse. Right now there's no way I know of to clean up space junk in orbit other than waiting for it to burn up, which could take years or tens of years.
It even has a name: https://en.wikipedia.org/wiki/Kessler_syndrome
Additionally, as other comments have alluded to, part of the FCC requirements that these spacecraft have to meet is a maximum deorbit time, which is (I believe) 25 years. For satellites as low as these ones were, that period will be lower.
I'm all for the FCC throwing the book at this company, but just want to make sure we don't have misconceptions as a community about what or why these things are regulated and how they work.
If you want to add some way to detect that you might hit something, it'd have to have some impressive range, as if you're in LEO going different directions with a 90 minute orbital period for each object, you have about 45 minutes to do something at best (when you just passed each other on one side of the earth, and you will collide as your orbits cross on the other side), although you can't really detect it until it's within line of sight, which brings it down to much less, maybe like 20 minutes. Radar or other detection systems also take a huge amount of mass and power to operate, which increases the cost. If your orbits go the same way, you do have some more time, and maybe multiple orbits to see that something is getting closer every pass, but then again, you can't really rely on that.
I've never been good at orbital mechanics, but I'm not sure how increasing the drag would allow you to get to a higher orbit (higher meaning altitude above earth). Reducing drag just makes you slow down slower, but I don't think will let you go to a higher orbit. The height of the orbit is related to how fast you are going (for example, a geosync orbit is 3.07 km/s, whereas LEO is 1.3–1.8 km/s). Drag will never make you go faster. I think you would get a more elliptical orbit, which would also add more atmospheric drag at your new lower perigee, also decreasing the lifetime. Even a low lifetime orbit for a cubesat could easily be 10 years, and if you lose communications with it and lose track of where it is at, it could be a hazard.
The amount you'd have to change the orbit also depends on the confidence of detection of the object you're trying to avoid (ie, how close you want to risk getting to it). If you're less sure where it is, you need to get further away from it in order to make sure you avoid it.
To sum up, you don't know when you need to do something, your ability to do something may be limited based on the craft doing the avoiding, and you may not have a lot of time to figure out you need to do something and then do it.
Why these things are regulated is because orbits around earth are basically a shared resource. How it works is very complicated. I used to work in the space industry, and I don't even pretend to be an expert.
These objects aren't just floating up there, they're travelling at tens of thousands of miles per hour. If they can't be tracked, they can't be avoided.
But here's the thing. Momentum. If you've tracked it once, you know its location for many months to come.
Not in low-earth orbit. Look at this graph of the ISS's altitude over time [1]. Atmospheric drag makes orbital dynamics too complicated for long-term predictions. Add in station-keeping [2] jitter, and one has a necessity for reliable tracking.
[1] http://images.huffingtonpost.com/2014-05-17-ISSaltitude.png
https://en.m.wikipedia.org/wiki/Space_debris
"Below 2,000 km (1,200 mi) Earth-altitude, debris are denser than meteoroids; most are dust from solid rocket motors, surface erosion debris like paint flakes, and frozen coolant from RORSAT nuclear-powered satellites."
And the journal Orbital Debris Quarterly
https://orbitaldebris.jsc.nasa.gov/quarterly-news/newsletter...
This is not accurate. Even if you ignore the big vertical jumps at each burn, the downward trend is very obviously irregular. Satellites in LEO experience a slight drag force from the Earth's outer atmosphere, and the magnitude of this force can vary unpredictably by orders of magnitude depending on space weather conditions.
Satellites in orbit are moving very quickly, so a slight change in altitude (i.e. orbital period) results in a very large change in position at any given future time. More importantly, the inaccuracies are compounded with each subsequent orbit. As a rough estimate, an uncertainty of 1m in the height of a satellite in LEO translates to a positional error of more than 100m/day. It is not possible to accurately predict the position of a satellite without ongoing observations.
Starting with the weakest reason first, but one that's also very important. Space is really big. There are some 6 figures of tiny things in space and thousands of larger things. This sounds pretty scary. But now imagine that we put 6 figures of tiny things, and some thousands of large things in random places in the US and set them on a random path. You can intuit that the odds of any collision are going to be extremely low. And now imagine the entirety of LEO. It is magnitudes larger than the USA of course.
The next is that objects tend to be going in the same direction. Rockets take advantage of Earth's rotation to get a 'head start' on their launch which means that most things end up going in the same orbital direction. Two things going the same speed with the same orbital characteristics will never collide. With different orbital characteristics, they will get two chances for collision per orbit with an extremely low chance of it occurring by chance.
And maybe the biggest point is another really cool and counter intuitive part of space. When we think of the USA we obviously just think of the ground. But of course there is a vertical axis in space. And the awesome thing here is what determines your altitude in space. It's entirely based on your velocity (well and the mass of whatever you're orbiting). In other words, objects cannot collide unless they're traveling at the same rate of speed. Pretty neat!
Another issue is that even at LEO, objects do experience some atmospheric drag. Any object in LEO that is not occasionally correcting its orbit (accelerating) will eventually come back down to Earth. This includes all of that tiny debris.
So now make the US absurdly vastly larger. And create multiple layers of the USA where any given car traveling at any given speed goes on a specific layer. And set them [almost] all in the same direction. And finally remove small stuff (or 'decommissioned' cars) over time. So sure, space debris is something to definitely keep in mind - but I think people don't really realize how relatively irrelevant this is. Another thing is that even if we did experience some catastrophic kessler syndrome level event it would mostly have no impact on things going through LEO (and not orbiting within it) simply because the massiveness of space just means the odds of an impact are so very low. So it would not kill space travel as the video states.
And lastly, necessity is the mother of all invention. There are an enormous number of viable ideas for removing debris from space. But there hasn't been that much of a push for them simply because it's not really necessary yet. If we reach a point when it becomes necessary, there are solutions.
So issue? Sure. "Massive" issue. Nah.
Not true. Satellite orbits have all kinds of inclinations, including polar and retrograde. Just because you watched the Space Shuttle on TV getting launched into a typical prograde orbit doesn't mean all orbiting objects do that.
> what determines your altitude in space. It's entirely based on your velocity (well and the mass of whatever you're orbiting).
You are greatly oversimplifying orbital mechanics. Satellite orbits are not perfectly circular, and they have more than one degree of freedom.
No, even that's not the case. If it were, the delta v of anticipated collisions would be low enough that they wouldn't pose a serious problem.
The Wikipedia article on the Kessler syndrome, linked to upthread, gives some useful references. One of them is an article on how a cupola window on the ISS was pitted by a microscopic piece of space debris. The pit is 7 mm across, about the size of what a small rock would put in a car windshield at highway speed. How fast would an object about 1000 times smaller (and therefore about a billion times less massive) have to be traveling to have the same impact energy? (Hint: it's about the same as LEO orbital speed--but that's orbital speed relative to the ground, not relative to objects on nearby orbits in the same direction.)
Geostationary orbit is approximately 22,200 miles above the surface. At that height, the usable sphere for a satellite is 8,630,000,000 square miles. Certainly a huge deal of that isn't overly usable (polar, etc.), but nonetheless.
That's my trivia for the day.
At the time of writing, SOCRATES shows seven approaches closer than 100 metres in the next few days:
https://www.celestrak.com/cgi-bin/searchSOCRATES.pl?IDENT=NA...
they will not survive reentry
Not so sure GPS would work well up in space, given that the signals are aimed down at the planet's surface.
"In GPS technology, the term "COCOM Limits" also refers to a limit placed on GPS tracking devices that disables tracking when the device calculates that it is moving faster than 1,000 knots (1,900 km/h; 1,200 mph) at an altitude higher than 18,000 m (59,000 ft).[2] This was intended to prevent the use of GPS in intercontinental ballistic missile-like applications.
Some manufacturers apply this limit only when both speed and altitude limits are reached, while other manufacturers disable tracking when either limit is reached. In the latter case, this causes some devices to refuse to operate in very high altitude balloons.[3]"
https://en.wikipedia.org/wiki/Coordinating_Committee_for_Mul...