Interesting stuff, it appears to be their own data (I'm guessing aggregated from sources like the UN registry and observation). I was curious about the statistics on satellite missions so I put it into a table:
Operational satellites by mission:
total 2154
Communications 740
Scientific 592
Navigation 135
Technology Development 109
Earth Observation 99
Surveillance 58
Engineering 20
Weather 13
Not Recorded 8
Early Warning 3
Search and Rescue 1
Space Station Flight 1
We use Cesium at https://ayvri.com (with some of our own magic sprinkled in). It is an incredible bit of software, completely agree with your comments regarding Patrick. He's also the driving force behind glTf and wrote the book on virtual worlds in webGL. https://www.amazon.com/Patrick-Cozzi/e/B004LGLPIA/ref=dp_byl...
If you want to see how long it takes for satellite orbits to decay in LEO, check this out. Illustrates how quickly some of these satellites would reenter without station keeping.
The amount of delta-V required to orbit opposite of Earth's rotation is immense and very few projects have wasted the resources on it. I think most collision concerns come from inclinations and changing orbital altitude due to atmospheric drag. These are predictable effects, but it gets dicey quickly if your surface area increases because your vessel explodes.
It's not as rare as you might think. All sun-synchronous orbits are slightly retrograde (inclination = 98 degrees or so at 600 km) in order to take advantage of the precession caused by the earth's equatorial bulge and maintain the same local solar time in the ground track.
Also, Israel always launches in a retrograde orbit, since they have neighbors to the east who would react too well to what looks for all intents and purposes like a missile launch, or to expended rocket stages dropped on their heads. For that reason, Israel launches retrograde over the Mediterranean.
Even neglecting a retrograde orbit, though, just a slight difference in inclination is enough to totally ruin your day. Even if you're only off by one degree, if you're travelling at 7.8 km/s your closing perpendicular velocity at the node crossing is 7800*sin(1 degree) = 136 m/s. That's almost 500 km/h, plenty fast enough to ruin your day.
Yea for sure.. I would hope that there is some rule now related to making sure things can be deorbited with some scheme relatively easily? For example a mandatory unit that attaches to the side of your satellite that has a small antenna only possible to communicate with using a high gain antenna on the ground that can transmit back using a battery that is only for that unit and can only command some relays to fire thrusters to de orbit the thing and read back basic telemetry to help validate what the slow down burn direction is.. anybody know how they accomplish this?
To deorbit a satellite, you need an antenna (to receive the command), electricity (working solar panel / battery), working on board computer, fuel, correct attitude determination. So basically you need a full working satellite. As soon as one of these element fails, your satellite is dead. At 10-20 k dollars per kg, you dont want to add another satellite to your already expensive satellite.
Concerning rules, there is some progress, because nobody wants a Kessler syndrome, too much is at stake. For instance, European satellites are launched only if they naturally deorbit in less than 25 years (for LEO, of course. Above a certain height, atmospheric drag is too weak).
Actually, the newly-proposed FCC rules would require fail-safe deorbit systems when operating above 550 km and below 2000 km. Above 550 km, most stuff takes more than 25 years to deorbit, and the NGSO volume below 2000 km is considered the most useful (and thus most likely to get crowded). These fail-safe systems should be designed to cause the satellite to deorbit within 25 years of activation.
I made a similar site 20 years ago (an applet, what else) and a lot of people seem to be wondering "how does it work" or "where does the data come from?". I can only describe how I implemented it, but it's probably similar.
Data is not "real time" for each satellite in any sense. But since satellites follow orbits, it's enough to have recent state, and you can extrapolate where they are. The data comes from places like NORAD, and has a standardized format called a "Two line element set". https://en.wikipedia.org/wiki/Two-line_element_set
Here is the current state of the international space station for example as described in a TLE:
It's mostly opaque but we can see near the end of the second line that at the current orbit means it does around 15.5 orbits per day.
When I implemented my app, I just grabbed some data from a public link with up to date TLE's. Such as this one, for the 100 brightest satellites is a good start for a simple visualization app.
Once you have the TLE for a satellite which describes where it was a while ago, you need a function that gives you the current state vector for the satellite, given the time delta since the known state. Far from earth this can be done approximately with simple orbital mechanics, but close to earth you need to account for athmospheric drag and also the uneven or "bumpy" gravitational field. At some point someone devised a set of algorithms for this called the simplified perturbations models in 1988 https://en.wikipedia.org/wiki/Simplified_perturbations_model...
Luckily, these functions were released together with a Fortran implementation, so porting it to whatever language you want is fairly straight forward. Here is an example port of SGP4 to python https://github.com/brandon-rhodes/python-sgp4/blob/master/sg...
I hope we get the GPS III constellation up and running before any catastrophic LEO cascades. Having a self sustaining common clock system that can run for centuries has a very high scientific value (and really, just a huge value for any industrial, commercial, and consumer applications).
From what information are you assuming these will run for centuries? Most sats have a design life of like 10 to 25 years max. Also keep in mind that station-keeping and correction data is mandatory to keep the accuracy in check. I think I read somewhere that after 180 days of un-corrected drift the GPS would be able to get you within a few km of your target - not meters/feet.
I was told by someone who follows theses things more closely than me that block III GPS would have an inter satellite network that could share clock information independently of ground control. While looking into it the closest I could find was references to OCX, which is ground based controls. So maybe we're not there yet idk.
Are there standard libraries or agencies or something for aggregating the latest data and then based on your satellite's planned trajectory, ensuring that you aren't getting too close to another satellite?
I am guessing that space is pretty big even in low earth orbit and so probabilities are small even with thousands of objects. But even so, if you are spending millions of dollars, you would want to have some idea rather than just keeping your fingers crossed.
Is there a global database or protocol or blockchain or something where satellite positional data is aggregated? Like if you are launching a satellite then you log into a website or something and enter the planned orbit. Or something.
Or is it just a bunch of random tracking efforts with duplication and incompletion?
The data for Spacebook, like almost all public satellite position data, comes from tracking radars run by the US Air Force. They have a public website and database with API at https://space-track.org.
I've been working on my own website using the space-track.org API to show you when/where/how to see satellites in the sky with your naked eyes from your own backyard. Hopefully launching soon.
How exactly does blockchain solve this problem, other than being the buzzword of the day?
The vast majority of this data comes from the United States Strategic Command's Space Surveillance Network, which provides orbit information in SGP4 format for public use:
Most of the current debris comes from an anti-satellite missile test (China) and 1 collision caused by an out-of-control (Russian COSMOS) satellite. So, basically stop blowing shit up in orbit and it should be ok.
What's neat is you can see the actual Starlink chain and a few other defined satellite trains. I'd link to it but I don't see a way to link directly to a particular satellite.
Not really. They're launched from a base at 28 deg N. So assuming they launch due east, you can get to a 56 deg inclination and spend less delta-v than you'd need to drop the inclination to zero.
I might be wrong, but I don't think they are data captured in real-time.
Based on a cursory understanding of the AGI STK, these satellite positions are calculated from ephemeris data which are updated on a regular basis (e.g. weekly). https://en.wikipedia.org/wiki/Ephemeris
The ephemeris data is updated approximately daily and also allows you to predict the satellite's position fairly accurately several days in the future. Satellites change orbits very infrequently, so it's close enough to real time for most purposes.
