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Are you seriously saying that you know all of the debris paths and speeds of both the explosive device and the satellites it destroys? Stuff flies everywhere, ad different speeds and different directions. Especially your direct hit scenario, which will be very asymmetrical, and send shrapnel all over the place.

If you consider the facts that only debris with only inclination changes isn't brought deeper into the atmosphere at some point and that most debris is small and even less aerodynamic than the original satellite, it becomes clear that around 300 km, several weeks or months does indeed seem like a reasonable estimate for a large part of the debris. Here's an analysis for a comparable US test.

"Unusable" is a standard field in the DECOM template, see https://celestrak.com/GPS/NANU...

And doing a little browsing, I see that SVN32 had an earlier notice: http://www.navcen.uscg.gov/?Do...

The earlier notice was of type FCSTUUFN -- Forecast Unusuable Until Further Notice: Scheduled outage of indefinite duration. And that notice says that the start time of that unusability period was 025/1500. And the start time of the unusability period in the DECOM notice you linked was 36 minutes after that: 025/1536. So, they said that it was going to be unusable around 15:00 and it was actually unusable at 15:36. And the notice itself was posted on Jan 20.

So I'm going to update my response from "I don't read that as a failure" to "definitely not a failure", barring an explicit statement otherwise by someone actually running the GPS constellation.

Ours was done during the cold war. China supposedly has no cold war. In addition, we picked one that was low enough (345 miles) AND SMALL so that minimal parts. In fact, the sat parts are already cleared out of there. In 2002, there were only 2 known pieces left and they came down already. And this was because USSR had spent 30 years developing their IS system (apparently starting in the 50's). They took out a number of satellites, though it is unknown exactly how many. In fact, USSR had a full blown production military system designed to take out larger number of sats and esp. the shuttle. But that was the cold war.

China's target was monstrous large and high (550 miles). It was bigger than all of the previous sats put together (well, the ones known). China's ASAT will have 60-90% of its mass in space in 100 years. As it is, USSRs multiple targets and USA's single target (excluding the malfunctioning sat that was taken out close to the edge of space) are no longer in space.

And no, their space program is NOT just 'funded' from the same pot as their defense. Their space program is 100% part of their PLA. It answers directly to their military structure, not their president or even their party. Their is no arms length between PLA and CNSA. That is the reason why CNSA is developing quick response rockets. USSR's space program was arm lengths between military and space program, but USA's was totally 100% separate systems from USAF. Like USSR's, it did some items for USAF, but that was in the cold war. China is not supposed to be in a cold war with the west. Or have they formally declared it?

BTW, I agree with your criticism of our nation as far as interfering in other nations. We should not be doing that. We had zero business getting involved in Iraq, Libya, and now iran. As it is, the only nation that we had any business getting into was afghanistan. And W should have completed that before deciding to screw up so many other places. We really are too deep into messing with other nations rather than paying attention to our own business (reminds me of the USSR before its collapse).

There are several objects listed from the launch (Object A through F), so here is Object A at least.
OBJECT A
1 37826U 11054A 11273.14391030 -.00000079 00000-0 00000+0 0 34
2 37826 049.4988 295.0663 5643789 354.0088 001.4266 04.54364902 18

(from http://celestrak.com/ )

The rate of orbital decay is highly dependent on the surface area to mass ratio of the object. Typical debris has little mass and a lot of surface area, so it decays very rapidly when compared to a satellite or other massive object. This PDF explains it well, and you can look at TLE files to get a feel for actual decay terms.

The EGRS-3 Sat launched in 1965 is still orbiting in an 894 x 927 km orbit. TIROS-1 was launched into a 693 km x 750 km orbit in 1960, and is still merrily orbiting away 51 years later at 638 x 672 km.

The oldest sat still in orbit is Vanguard-1. It was launched into a rather elliptical orbit with the perigee near 650 km, but only massed 1kg!

I wonder if the app gets the position from the internet or if it's using the connection to download the telemetry data and doing the calculations itself. If it's the latter, a sync before going on the trip would be fine. AFAIK, the decay is not too bad for the calculated position for at least a couple of days. I don't even remember how frequently NORAD provides updates for the telemetry data.

if it's the former (just uses the internet connection to talk to a NASA/NORAD web server to get the position) then you're hosed. Unless you implement the algorithms in the Spacetrack report and create the app yourself.

It's not all that difficult. I did it for a class about 6-8 years ago and used it to track a weather satellite. Actually downloaded the TIFF weather map. Was a fun class.

For those of you who have WXTrack or gPredict or even the rusty old DOS version QuikTrak 4. Here are the 2-Line track elements (from celestrak.com) to plug in to the above software or similar and you can plot the course and collision possibilities yourselves. (Start of Sat ID Line) GALAXY 15 (G-15) (Start of Line 1) 1 28884U 05041A 10127.51136922 .00000076 00000-0 10000-3 0 8255 (Start of Line 2) 2 28884 0.1250 77.0169 0002855 329.6075 230.3636 1.00283287 16733 If you need further help understanding these NORAD 2-Line elesets, please see this page: http://celestrak.com/columns/v04n03/#FAQ01 for the manual key in entry in your tracking software. Depending on available sunlight angle and sat size, you can also plot the times and locations in the sky of when it is visible, for like re-entry burn up. That's if you happen to be lucky/unlucky to be close enough to see it. From my "Ham radio sat days", it is best to get fresh tracking data, every week, for the best results. I did a lot of this in '94 or '96 and back then it was pretty cool to run a digital signal from a pc linked hand held radio in Kansas and bounce it off of the Soviet MIR space station or sometimes the non-military shuttle hops, just to get to Chicago, IL! Good luck and happy sat hunting!

Well, this is not entirely without precedent. Even the field of Physics employes this method of specifying things that are complex enough that warrant a "model" which is highly dependent on what the model chose to include or exclude. For example, in tracking satellites, you would think that you should be able to use Physics and the myriad of formulas alone to come up with the position of satellites. But because real world physics (think drag, friction, N-body G forces etc) is too hard to figure out and are often hand-waved away (thus the model), NASA had to devise a set of algorithms to communicate a way to track satellites. They then publish the telemetry at regular intervals which are then run through those algorithms to find out where any of the satellites are at any given time. Last I worked on it, I was looking at Fortran programs which was used as the spec for the algorithm. Now, think about it, how better to describe an algorithm than an actual working program?

see: SGP4 and this in particular.

During most of the year, geostationary satellites spend 100% of the time in sunlight. During "eclipse season" (which happens around the spring/fall equinoxes), they get eclipsed, for a few minutes up to about 70 (at the peak of the season). A discussion of this can be found here: http://celestrak.com/columns/v04n09/

During those times, you could redirect from another satellite, use an alternative power source (batteries, capacitors, fueled generators, etc), and/or have a "brownout". Power outages suck, but if you're in a place where conventional power sources are unavailable/impractical/infeasable, it's better than nothing.

There's no sense in trying to keep secret data that anyone with binoculars can track. The military satellites, those that can read your licence plates, are so big and in low orbit that many people and organizations around the world keep track of them.
You can find that data from independent sites in the internet and try to watch if you can spot them.

The NORAD tracking data on both active satellites and debris is listed here.

I guess no one is cross checking the orbits of all satellites?

Yes, of course, they certainly ARE watching all satellites!

So why, oh, why didn't somebody point a fleet of telescopes at the expected collision/spread area and get us some of the best news-as-it-happens, stuff that matters, scientifically-useful video footage ever!?!slash! In all seriousness though, getting video of these events seems a no-brainer good idea. A shame as this one sounds like it was spectacular. I suppose at this rate there's always next time. and the time after that. and...

I guess no one is cross checking the orbits of all satellites?

Yes, of course, they certainly ARE watching all satellites! You see, these birds cost something in the order of $100 million each, don't you think someone is being paid to take care of them?

Well, of course, if it's something between a broken satellite that never reached its intended orbit, and a satellite from a bankrupt company that never had any profit, that's different. It's not as if they were true operating satellites, is it?

Actually, the sun does set in GEO. Just not for very long, and only at certain times of the year. Eclipse seasons for a geostationary satellite occur around the vernal and autumnal equinoxes. The seasons last around 40-50 days, with maximum sun-occultation duration of about 72 minutes. A discussion of the relevant orbit geometry can be found here.

The usual format is NASA 2-line format. People (including me) have been using it to track satellites for years.

The orbital models have been refined over the years. The latest version I've seen is this one.

...laura

The usual format is NASA 2-line format. People (including me) have been using it to track satellites for years.

The orbital models have been refined over the years. The latest version I've seen is this one.

...laura

http://celestrak.com/events/Xichang-ASAT4.wmv

Good model of the debris field caused by the China ASAT test. As you mention, "stuff" doesn't just fly everywhere.

Read these:
DirecWay info - http://www.fchorizon.com/direcway.html
STARBand info - http://searchwebservices.techtarget.com/sDefinitio n/0,,sid26_gci560980,00.html
Why communications birds use Geostationary orbits - http://celestrak.com/columns/v04n07/

1) I work for an aerospace company, and I recently needed some way to get NORAD TLEs from Celestrak. Never mind what TLEs are, I went to CPAN and found what I needed in a few minutes. How does Ruby compare to Perl in available libraries and utilities? If I have to get the TLE specifications and code my own functions in Ruby, sorry, but I'd rather cope with Perl's shortcomings.

2) Occasionally I have to do some web applications to access corporate databases in Oracle, Ingres, and Postgres. The data contains international characters, which may be in UTF or ISO-8859, I need support for both and an easy way to shift between them, often in the same application. For this kind of work I use PHP together with the eGroupWare suite. I have no need for very complicated code here, these are mostly simple web forms and tables, which PHP+eGroupWare handle quite well. Using the built-in etemplates utility I can code applications very quickly.

3) For really complex work I use C, or C++ with Qt if there is need for a GUI. I often create prototypes for my C code, using either Perl, Python, or Matlab to develop some of the algorithms. After I have the algorithm, I reimplement it in C using the many libraries available, such as GSL, Lapack, or FFTW, for instance.

With all that, I have yet to find a reasonable niche where Ruby would fit, with or without Rails. I can see how someone who wants to learn only one language would think Ruby is the best, but I cannot imagine being more productive in Ruby than in the languages I use for each of the jobs I described.

And the attitude one finds in Slashdot "hey stupid, Ruby is 'teh' language, you must be a troll" doesn't help either. For any other language I can find websites that give detailed descriptions of its good and bad points, but I have seen very little on comparing Ruby with other languages. From the little I have seen, it gives the impression of being somewhat remotely related to Lisp, like Python. How about creating a site that shows some examples comparing code written in Ruby with the same program in Python, Perl, C, PHP, Java, etc?

1) I work for an aerospace company, and I recently needed some way to get NORAD TLEs from Celestrak. Never mind what TLEs are, I went to CPAN and found what I needed in a few minutes. How does Ruby compare to Perl in available libraries and utilities? If I have to get the TLE specifications and code my own functions in Ruby, sorry, but I'd rather cope with Perl's shortcomings.

2) Occasionally I have to do some web applications to access corporate databases in Oracle, Ingres, and Postgres. The data contains international characters, which may be in UTF or ISO-8859, I need support for both and an easy way to shift between them, often in the same application. For this kind of work I use PHP together with the eGroupWare suite. I have no need for very complicated code here, these are mostly simple web forms and tables, which PHP+eGroupWare handle quite well. Using the built-in etemplates utility I can code applications very quickly.

3) For really complex work I use C, or C++ with Qt if there is need for a GUI. I often create prototypes for my C code, using either Perl, Python, or Matlab to develop some of the algorithms. After I have the algorithm, I reimplement it in C using the many libraries available, such as GSL, Lapack, or FFTW, for instance.

With all that, I have yet to find a reasonable niche where Ruby would fit, with or without Rails. I can see how someone who wants to learn only one language would think Ruby is the best, but I cannot imagine being more productive in Ruby than in the languages I use for each of the jobs I described.

And the attitude one finds in Slashdot "hey stupid, Ruby is 'teh' language, you must be a troll" doesn't help either. For any other language I can find websites that give detailed descriptions of its good and bad points, but I have seen very little on comparing Ruby with other languages. From the little I have seen, it gives the impression of being somewhat remotely related to Lisp, like Python. How about creating a site that shows some examples comparing code written in Ruby with the same program in Python, Perl, C, PHP, Java, etc?

> ...would an American colony be bound by law to be in a
> geosynchronous orbit over the U.S at all times?

What a wonky idea! In any case, it is not possible for anything to be in geosynchronous orbit over the US.

AFAIK, NASA never offered anonymous FTP access. Celstrak discontinued it years ago. NASA might have offered FTP access for "superusers" which involved quite a bit more paperwork then the Space-Track user application.

My bad, I meant anonymous http. Here is the link:

http://www.celestrak.com/NORAD/elements/noaa.txt

This worked fine up 'til NASA's server shut down. Space-track.org doesn't allow redistribution which is why Celestrak is now effectively down.

The only shenanigans I can see are with the legislation that placed the additional restrictions on the data. Come on. Anyone with the technology to actually try and shoot down these things probably already has the technology to track them. This doesn't really protect anything. It just presents additional hurdles to legitimate users of the information.

plover writes "Due to Congressional legislation passed quietly in 2003, the Air Force Space Command will no longer distribute space surveillance data via NASA. There was supposedly a three year transitional period when the data was to be made available via a NASA web site, but earlier this month their transitional server went down hard. NASA has decided not to rebuild it. (It was scheduled to be shut down on 31 March 2005 anyway.) The only way to obtain satellite data now is by signing up with the official Space-Track website. Part of the agreement to necessary to obtain data from their site is not to redistribute it. Of course, amateurs are still free to redistribute their observations, including those of classified satellites."

Actually, Nasa did claim to be tracking just about everyting in orbit - there was a special on it on the discovery channel and the methods they used. The Space Control Center in Cheyenne Mountain is responsible for it. Read all about it

The problem is orbit inclination. Shuttles simply don't have the fuel on board to shift inclination from Hubble's orbit to ISS's orbit.

More specifically (from Celestrak)

Hubble: 28 degrees inclination

ISS: 51 degrees inclination

Exercise for the student: work out the required delta V (here's a useful reference). Compare with the Shuttle's on-orbit delta V. It's cheaper (and lots easier) to land and get a fresh launch.

...laura

Yes, you're right, I was thinking of a geostationary orbit because it's a requirement for a space elevator.

All geosynchronous satellites occupy positions in the same orbital path, which forms a ring in the plane of the earth's equator.

Wrong. Geosynchronous != geostationary. Geostationary implies an infinitely thin ring around the equator, geosynchronous implies only keeping pace with the Earth's rotation, and even that can be done sloppily.

Perhaps you're really the 999,999th monkey? (-:

ISS' inclination is about 51 degrees, which is pretty big (ie, it's over 45 degrees off of the equatorial line). I don't remember what Columbia was at, but that wasn't it. To get the Shuttle up to that declination from their orbit would have taken a buttload of fuel, or a lot of time, neither of which were available.

ISS is indeed at 51 degrees, while STS-107 was in a 39 degree orbit. ISS is in a slightly higher orbit, too. My usual source is Celestrak. It doesn't matter how much time you have: there is a minimum delta V to change from one orbit to another. If you don't have it, you don't go there. The Shuttle's on-orbit delta V is very small.

Hubble, by the way, is in a higher orbit still, but a 28 degree inclination. A Shuttle can get there by launching due east from Kennedy (28 degrees latitude) with a reduced payload.

For the real dirt on all this orbit stuff, my favourite reference remains Fundamentals of Astrodynamics by Bate, Mueller and White.

...laura

Sirius' three satelites are in elliptical orbits, and two of the three are over the continental US at all times.

It is more likely they are not elliptical, rather, geosynchronous with a non-zero inclination. This results in them tracing small figure 8's centered about the equator. Each satellite probably traces the same track , each 120 degrees out of phase.

I know quite a few hams with access to this equipment. It's fairly easy to put together a satellite station, including dsp for demodulating various encoding methods. Hacking wireless data streams has been going on for the last 20 years, it just isn't as mainstream as say, hacking AOL. There is readily available code on the net for decoding all kinds of data streams, and as for LEO's moving... yeah, they move. Thats what az-el rotators are for. Again, you can buy one for under $1000, or build one out of a couple of cheap TV rotators. Hook that up to a controller, fire up your favourite tracking package and away you go. The element sets for most non-military satellites are readily available.

Simple satellites such as the NOAA apt satellites are easy to receive and demodulate, and Monitoring Times had a nice article on decoding (by hand) Russian satellite telemetry.

It isn't a matter of anything but time, and a desire to do it for the sake of doing it. My advice? Use encryption. Strong encryption.

Keplerian Elements for most satellites, links for tracking packages, and telemtry decoding packages are available at celestrak, as well as many other places:

http://www.celestrak.com

It's difficult, but not unreasonable, because we do have precise coordinates. Want to have a pretty good idea of where the ISS is right now? Here is a state vector, and this or this software will let you propagate that vector. The really difficult part in the whole process isn't tracking, it's getting escape velocity out of your nerf.

It's difficult, but not unreasonable, because we do have precise coordinates. Want to have a pretty good idea of where the ISS is right now? Here is a state vector, and this or this software will let you propagate that vector. The really difficult part in the whole process isn't tracking, it's getting escape velocity out of your nerf.

If you are not familiar with NORAD 2-line elements, look at celestrak's documentation. You can also look at celestrak's software archive.

Paper: An Operational and Performance Overview of the IRIDIUM Low Earth Orbit Satellite System -
Stephen R. Pratt, Richard A. Raines, Carl E. Fossa Jr., and Michael A. Temple Department of Electrical and Computer Engineering, Air Force Institute of Technology

If you are really interested in playing around with looking at the constellation, take a look at one of the best product's around for visualization and prediction, AGI's STK . You can download a modelling limited version of their software for free from their "Resources" tab.

If you are not familiar with NORAD 2-line elements, look at celestrak's documentation. You can also look at celestrak's software archive.

Paper: An Operational and Performance Overview of the IRIDIUM Low Earth Orbit Satellite System -
Stephen R. Pratt, Richard A. Raines, Carl E. Fossa Jr., and Michael A. Temple Department of Electrical and Computer Engineering, Air Force Institute of Technology

If you are really interested in playing around with looking at the constellation, take a look at one of the best product's around for visualization and prediction, AGI's STK . You can download a modelling limited version of their software for free from their "Resources" tab.

If you are not familiar with NORAD 2-line elements, look at celestrak's documentation. You can also look at celestrak's software archive.

Paper: An Operational and Performance Overview of the IRIDIUM Low Earth Orbit Satellite System -
Stephen R. Pratt, Richard A. Raines, Carl E. Fossa Jr., and Michael A. Temple Department of Electrical and Computer Engineering, Air Force Institute of Technology

If you are really interested in playing around with looking at the constellation, take a look at one of the best product's around for visualization and prediction, AGI's STK . You can download a modelling limited version of their software for free from their "Resources" tab.