Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror
Communications Earth Transportation

Geostationary GPS Satellite Galaxy 15 Out of Control 379

Posted by timothy
from the geo-wobby dept.
Bruce Perens writes "The Galaxy 15 commercial satellite has not responded to commands since solar flares fried its CPU in April, and it won't turn off. Intelsat controllers moved all commercial payloads to other birds except for WAAS, a system that adds accuracy to GPS for landing aircraft and finding wayward geocaches. Since the satellite runs in 'bent pipe' mode, amplifying wide bands of RF that are beamed up to it, it is likely to interfere with other satellites as it crosses their orbital slots on its way to an earth-sun Lagrange point, the natural final destination of a geostationary satellite without maneuvering power." (More below.)
Bruce continues: "The only payload that is still deliberately active on the satellite is its WAAS repeater. An attempt to overload the satellite and shut it down on May 3 caused a Notice to Airmen regarding the unavailability of WAAS for an hour. Unsaid is what will happen to WAAS, and for how long, when the satellite eventually loses its sun-pointing capability, expected later this year, and stops repeating the GPS correction signal. Other satellites can be moved into Galaxy 15's orbital slot, but it is yet unannounced whether the candidates bear the WAAS payload."
This discussion has been archived. No new comments can be posted.

Geostationary GPS Satellite Galaxy 15 Out of Control

Comments Filter:
  • by LostCluster (625375) * on Sunday May 09, 2010 @07:02PM (#32150376)

    Here's a list of what AMC-11 is used for [lyngsat.com] on Lyngsat.

    Basically, if this wayward sat gets in the way, the average cable/DBS subscriber in the USA is going to wonder where half their digital channels went.

  • by Manhigh (148034) on Sunday May 09, 2010 @07:07PM (#32150404)

    It should be mentioned that the stable libration points for geostationary satellites are earth-relative (105 deg west, 75 deg east) and are not the same as the Sun-Earth lagrange points (such as those occupied by SOHO and other observation satellites). If we could get spacecraft without maneuvering capability to perform that orbital transfer, we'd be much closer to living in a Star Trek-esque world.

  • GET READY (Score:1, Informative)

    by Anonymous Coward on Sunday May 09, 2010 @07:27PM (#32150536)

    none of the GPS satellites are 'hardened' against solar flares. This one went down for just a B flare and the next solar cycle has just begun!

  • by LostCluster (625375) * on Sunday May 09, 2010 @07:28PM (#32150540)

    Yes, but it carries a WAAS signal which your consumer "GPS" unit uses to increase the accuracy it's measurements. So, if this gets too far out of position without shutting off, your consumer GPS might get confused. Exact impact hasn't been computed yet.

  • by Anonymous Coward on Sunday May 09, 2010 @07:35PM (#32150574)

    Not just consumer GPS use WAAS. It was started by the FAA so that aircraft could safely use GPS instead of radio beacons. Therefore most commercial/industrial GPS use it too. About the only people who don't use it will be surveying GPS, which use DGPS to get even greater accuracy than the WAAS corrected signal.

  • by r6_jason (893331) on Sunday May 09, 2010 @07:36PM (#32150584) Homepage
    It isn't GPS, it's WAAS. http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System [wikipedia.org] which is an "air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area."
  • Re:Target practice? (Score:5, Informative)

    by TooMuchToDo (882796) on Sunday May 09, 2010 @07:43PM (#32150612)
    *MORBOR*: That is not how orbital mechanics works!

    You want to hit the satellite away from the direction it's orbiting in, so that it loses enough orbital velocity to descend into the top-most part of the atmosphere where drag will slow it down even further and pull it down.

  • by mpoulton (689851) on Sunday May 09, 2010 @07:44PM (#32150630)

    This is a commercial communications satellite that hasnothing to do with the Global Positioning System

    It is not a GPS satellite, in that it is not part of the constellation of satellites that provide position reference. However, as TFA and the other links say, this satellite is one of only two that operate the Wide Area Augmentation System. WAAS uses ground-based GPS receiving stations with known positions to generate a correction signal which increases the accuracy of GPS position fixes to less than 25ft within North America and surrounding areas. Without WAAS, plain GPS can have error in the hundreds of feet. Without the accuracy provided by WAAS, GPS navigation cannot be used for instrument flight approaches - one of the most critical, important, and common uses of GPS today. If this satellite fails, the WAAS system will remain operational throughout most of its original coverage area - but will almost certainly fall outside the reliability limits required for instrument flight certification. It will be a very serious problem for many commercial users of GPS, and possibly for some military applications as well.

  • GEO /= GPS!!!! (Score:5, Informative)

    by dev_alac (536560) on Sunday May 09, 2010 @07:45PM (#32150642)
    There are No GPS satellites in GEO. They have their own special orbits. The title is really, really wrong... http://en.wikipedia.org/wiki/Gps#Space_segment [wikipedia.org]
  • by MasterOfMagic (151058) on Sunday May 09, 2010 @08:03PM (#32150732) Journal

    According to Wikipedia, all television signals have been transferred to other satellites [wikipedia.org]. So unless your cable company hasn't received the memo, there should be no interruption of service.

  • by Geoffrey.landis (926948) on Sunday May 09, 2010 @08:10PM (#32150764) Homepage

    Right. This has nothing to do with Lagrange points.

    This is related to the fact that the Earth is not perfectly spherical.

  • Re:GEO /= GPS!!!! (Score:3, Informative)

    by ebob (220513) * on Sunday May 09, 2010 @08:18PM (#32150812) Homepage

    There are No GPS satellites in GEO. They have their own special orbits. The title is really, really wrong... http://en.wikipedia.org/wiki/Gps#Space_segment [wikipedia.org]

    Um, well, actually there are. "The [WAAS] satellites also broadcast the same type of range information as normal GPS satellites, effectively increasing the number of satellites available for a position fix." http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System [wikipedia.org] The title seems okay to me.

  • Re:Target practice? (Score:2, Informative)

    by kcitren (72383) on Sunday May 09, 2010 @08:24PM (#32150844)

    apart from the Chinese

    Well, the US did it. See [http://en.wikipedia.org/wiki/USA-193]

  • Re:Target practice? (Score:4, Informative)

    by Wyatt Earp (1029) on Sunday May 09, 2010 @08:33PM (#32150886)

    Think before you type.

    The YAL-1 doesn't "heat up and short out guidance systems", it and the NC-135 used a laser to burn through the missile's wall and causes a structural failure.

  • Re:Light pressure (Score:5, Informative)

    by mmontour (2208) <mail@mmontour.net> on Sunday May 09, 2010 @09:06PM (#32151048)

    Really... massless particles can create pressure now?

    Yes. Photons carry momentum despite having zero rest mass.

  • Re:Light pressure (Score:3, Informative)

    by voidptr (609) on Sunday May 09, 2010 @09:11PM (#32151080) Homepage Journal

    Yes, they can: http://en.wikipedia.org/wiki/Solar_Sail [wikipedia.org]

    Massless doesn't mean they don't have momentum.

  • Re:GEO /= GPS!!!! (Score:3, Informative)

    by Vellmont (569020) on Sunday May 09, 2010 @09:17PM (#32151098) Homepage


    The [WAAS] satellites also broadcast the same type of range information as normal GPS satellites, effectively increasing the number of satellites available for a position fix.

    The WAAS satellites aren't merely another GPS satellites, it's entirely different. GPS signals have errors based on a variety of different variables (clock errors, ionosphere propagation variability, etc). The WAAS satellites broadcast a series of correction signals that account for these errors. The end effect is increased accuracy.

  • Re:Light pressure (Score:5, Informative)

    by The Hatchet (1766306) on Sunday May 09, 2010 @09:20PM (#32151112)

    Light actually does have a pressure. It is incredibly small, but in enormous quantities (like the sun or lasers) it can be quite powerful. I believe something like Intensity / c is radiation pressure formula. Not sure though. But it definitely has pressure, without radiation pressure our creation of Bose Einstein condensates would totally fail. Photons may not have rest mass, but they have some momentum because matter is just a form of energy. E.^2=M.^2.*c.^4 Its not much, but enough of it has measurable effects. A good part of the time the pressure is converted to heat (like on earth, or in our metal cutting lasers).

    Uh, YES. Reality is a fantastic thing, i would suggest learning more about it, it is an enriching experience. Or you could just go on being a dumb-ass making the world a harder place to live in because people that know things have to sit around and explain things to you like a five year old, or just accept you people attempting to influence the world around you without understanding the possible consequences of your actions.

  • Re:A funnel (Score:3, Informative)

    by Anonymous Coward on Sunday May 09, 2010 @09:27PM (#32151154)

    Generally speaking, we don't have any sort of rocket that can lift 100 tons up to 36,000km geosync orbit. I don't think that Saturn V can even do it. An Ares V might be able to do it, but of course we won't know until one is actually built. A typical geosync payload is 6 tons, or 12 tons to GTO.

    dom

  • Re:GEO /= GPS!!!! (Score:5, Informative)

    by flatulus (260854) on Sunday May 09, 2010 @09:31PM (#32151166)

    You are correct that Galaxy 15 is not a Navstar (GPS) bird. But the title is not entirely correct, because WAAS (Wide Area Augmentation Service) is a signal which is sent to terrestrial receivers (i.e. your WAAS enabled GPS receiver) with position correction information. This information helps WAAS enabled GPS receivers to cancel out known (so called "systematic") errors that would otherwise affect your GPS receiver's positioning accuracy.

    So while Galaxy 15 is not a GPS satellite, it does participate in delivering high accuracy geopositioning in concert with the actual GPS birds.

  • by Low Ranked Craig (1327799) on Sunday May 09, 2010 @09:57PM (#32151308)
    I think are referring to a mascon [wikipedia.org]/
  • by LostCluster (625375) * on Sunday May 09, 2010 @10:43PM (#32151554)

    You're confusing the issue. The wayward satellite is useless, and all of it's content has been moved elsewhere. The problem is the late-May to early-June threat to AMC-11's signals... which is still functional and "evasive maneuvers" for it are planned to keep it's signals going, but the jury's out as to whether this is going to work.

  • by imroy (755) <imroykun@gmail.com> on Sunday May 09, 2010 @11:18PM (#32151736) Homepage Journal

    AFAIK, WAAS and other Satellite Based Augmentation Systems (SBAS) are basically differential-GPS done on a large scale. The position of the satellites doesn't matter, they're simply being used to distribute the correction data on a global scale. Other systems are ground-based and limited in their range.

    Also, the usefulness of WAAS/SBAS is greatly diminished since selective available (SA) has been off for over a decade. One disadvantage is that it takes longer for an SBAS-using receiver to get a fix since it has to wait for the correction data to reach it.

  • A tad late for first (Score:2, Informative)

    by elsJake (1129889) on Sunday May 09, 2010 @11:25PM (#32151774)
    Some are doing it already http://tech.slashdot.org/article.pl?sid=09/04/21/151225
  • Re:Target practice? (Score:4, Informative)

    by THE anonymus coward (92468) on Monday May 10, 2010 @12:42AM (#32152010) Homepage

    Not to mention the fact that the Shuttle doesn't have the thrust necessary to put it into Geosync... heck, it can't even make it to GTO. VERY out of reach.

  • by Anonymous Coward on Monday May 10, 2010 @12:55AM (#32152048)

    This is (part of) the official notice we were given regarding the issue (I work at a top-20 ISP) which was sent to us on April 12th.

    . Intelsat has notified us that due to an anomaly, the programming currently available via the Galaxy 15 satellite will be moved to the Galaxy 12 satellite. Intelsat assures us that this transition will be turn-key and require little (if any) involvement by our affiliates.
    The [...] video and data feed will be transmitted from Galaxy 12 via the same transponders and frequencies. Systems properly aligned to the 133.0 degree orbital location will require no adjustments or actions.
      The East and West Coast feeds will switch at the same time. The transfer should take no more than 15 minutes.
    During the April 17th transition, some networks are offering to play a 30 minute program directly from our local server in your head-end to avoid any loss of video feed.
    Again, we do not anticipate any service issues do to the Galaxy 15 technical problem or the transition to Galaxy 12. Any systems noting performance degradation during this period may need to re-peak their receive antenna to return to optimal performance

    Incidentally, the transition went fine with no major issues.
    The only remaining problem is that the old sat is still broadcasting, and since it has lost orbital controls if the antenna happens to aim in the wrong place it will still flood out signals. Also, as pointed out in the article, there is still the GPS rebroadcast service which needs a new home.

  • Lagrange point!? (Score:4, Informative)

    by Brett Buck (811747) on Monday May 10, 2010 @02:19AM (#32152484)

    Since the satellite runs in 'bent pipe' mode, amplifying wide bands of RF that are beamed up to it, it is likely to interfere with other satellites as it crosses their orbital slots on its way to an earth-sun Lagrange point, the natural final destination of a geostationary satellite without maneuvering power."

        LAGRANGE POINTS? Good God almighty? What in the holy heck are you talking about? That's just ridiculous. It's not going to go to the Lagrange points (any of them). If nothing else there's no maneuvering and so the semi-major axis is FIXED at essentially geosynchronous period. What will happen is that that it will drift at varying speeds on the order of fractions of degrees a day, speeding up as it goes towards the gravity wells, passing through at pretty high speeds, then climbing back out, slowing all the time. I haven't checked the TLEs but it will either oscillate back and forth in one of wells or pass from one to the other. Just like dozens of other "died in place" spacecraft that had exactly the same problem. Eventually as the inclination changes it might go over the side of the hill (since the wells are 3-dimensional) like Skynet II/9354. Look that one up, or DSCS II/Flight II/9432 TLEs and history, that's what it's going to do.

            Brett

           

  • Re:Bastard (Score:5, Informative)

    by MrZilla (682337) on Monday May 10, 2010 @03:10AM (#32152624) Homepage

        You really don't want to just pop one in orbit though. It'll leave one heck of a mess up there. It's not just debris, it's radioactive debris.

    Not only that, but the blast itself will fry more satellites, which will have to be nuked in turn.

    http://en.wikipedia.org/wiki/Operation_starfish_prime [wikipedia.org]

  • by batistuta (1794636) on Monday May 10, 2010 @04:59AM (#32153020)
    WASS is used to provide corrections to upper atmospheric disturbances in the GPS signal. It works like this: you have a lot of beacons on ground, mostly close to the shore but pretty much everywhere in the country. These stations know *exactly* where they are, but they anyway measure their position via GPS. By looking at the difference between what GPS says and what they know, they calculate the effect of these atmospheric disturbances. These are uploaded to a central system and get in turn broadcasted via WASS. WASS signals get used mostly by air and maritime vehicles in the North America. Europe has something similar called EGNOS, that depending on the country it could be used with limited advantage on terrestrial measurements. In Germany for instance, the angle to EGNOS is about 20 degrees which makes it almost impossible to capture free-line-of-sight by anyone that is not airborne or in open waters. Now back to the issue. One WASS satellite is failing. There are two WASS satellites and we are fortunate that the one about to fail is not the most important one. This link has some nice images showing the coverage. Sorry for copy-pasting, it's my first post and don't know how to add tags yet. http://www.gpsworld.com/gnss-system/augmentation-assistance/news/failure-imminent-waas-geo-satellite-9841 [gpsworld.com] The problem is that airspace people don't like single point of failure so having one satellite only is a yellow lamp. How this will affect air traffic is still to be seen. GPS accuracy is about 16m with a good view, and when traveling 200 mph during approach, this is not crucial if you ask me. Maritime is something different. You don't wanna sail in Sweden and hit an underground island because you are 10m too far left. For final approach to runway and landing WASS has never been an enabling technology, so business as usual. The US will either replace the satellite or bring the functionality to another one. Until then, people must know that WASS could be out for a few seconds every once in a while. Nothing new really. None of us here will probably feel anything particular happening in the sky.
  • Re:Target practice? (Score:2, Informative)

    by Calinous (985536) on Monday May 10, 2010 @05:46AM (#32153224)

    Drag is an issue in the Low Earth Orbit (some hundreds of kilometers up). However, Geo Stationary Orbit is at some 36 000 km above ground (more than 20 000 miles)

  • by Skapare (16644) on Monday May 10, 2010 @06:20AM (#32153360) Homepage

    ... located at each individual airport. The airport already knows exactly where it is. It can receive the GPS signal and see how far off it is ... specifically for that airport. Then it would transmit that correction data in real time over a local UHF frequency that can serve approaching planes out to some distance (perhaps 100km). Nearby airports use different frequencies which get selected when the target airport is selected and GPS indicates they are within range.

    They could also spend more money and put up a triangulation based TPS that would allow accurate terrestrial positioning independent of GPS. That would be in addition to final approach guidance systems. That is, of course, if you feel warm and cozy about having extra redundant systems serving the airplane you are on.

  • by weedenbc (719416) on Monday May 10, 2010 @07:13AM (#32153624)
    Wow - this has to be in the Top 10 Worst Article Summaries ever on Slashdot. And why is the link pointing to a CSMonitor dupe instead of the original story at Space.com which has the best coverage? Most of the other commenters already pointed out the problems (it's not a GPS satellite, the libration points are not Earth-Moon Lagrange points, etc), so I will just point everyone to the real articles with real facts on this story: http://www.space.com/news/out-of-control-satellite-threatens-others-sn-100503.html [space.com] http://www.space.com/news/zombiesat-galaxy-15-shutdown-fails-sn-100505.html [space.com]
  • by russotto (537200) on Monday May 10, 2010 @10:13AM (#32155770) Journal

    Why not a ground based WAAS located at each individual airport.

    Because the "WA" is "Wide Area". If you have one at an airport, it's an LAAS (Local Area Augmentation System), and they do exist.

  • Re:Target practice? (Score:1, Informative)

    by Anonymous Coward on Monday May 10, 2010 @10:45AM (#32156460)

    apart from the Chinese

    Well, the US did it. See [http://en.wikipedia.org/wiki/USA-193]

    ... you realize there's a pretty big difference between blowing up a satellite in a high stable orbit, and blowing up one which is in a low unstable orbit to prevent hazardous materials from causing problems?

    You realize that the debris from the Chinese satellite is still in orbit, and will be for decades, while the American satellite debris was mostly gone within a day?

    And before you try and say you were 'correcting' the guy, read what he said:

    very hesitant to gratuitously blow stuff up in orbit, because the debris stays in orbit

    The satellite blown up by the US was suborbital at the time of its destruction. So... in short, everything you said was wrong.

We will have solar energy as soon as the utility companies solve one technical problem -- how to run a sunbeam through a meter.

Working...