Global ADSB Tracking about to go live

[ve3id]

SpaceX began launching Iridium’s NEXT satellites, equipped with Aireon’s ADS-B receivers, from Vandenberg Air Force Base in California on January 14th, 2017. By May 2017, FlightAware will begin providing services fusing Aireon’s space-based ADS-B with FlightAware’s existing flight tracking systems. By early 2018, Iridium and spaceX will have launched all 72 satellites (66 in-service and 6 on-orbit spares) and global ADS-B coverage will be available 24/7.

[Lonewolf_50]

Who pays for it and how much does it cost?

[donotdespisethesnake]

ANSPs pay for the service, how much is negotiable. FAA have a "letter of intent" with Aireon, annual fee is in the region of $100 million.
Several ANSPs are part of the Aireon consortium, I guess they get cheap rates.

[atakacs]

Interesting, I wasn't aware of this development.

Does it require new hardware on the aircrafts? Any reference / tech information (tried to google it but did not find much)?

[DaveReidUK]

Does it require new hardware on the aircrafts?

No. That's the whole point.

This will allow for 100 percent global surveillance using the same ADS-B signal that aircraft already transmit.It's Just ADS-B (https://aireon.com/resources/its-just-ads-b/)

[peekay4]

ANSPs pay for the service, how much is negotiable. FAA have a "letter of intent" with Aireon, annual fee is in the region of $100 million.

Along with ANSPs the bulk of Aireon's customers will be airlines and airports. (There are many more of them than ANSPs).

Airlines in particular use position data to monitor routes and continuously improve operational efficiency. In the future global flight tracking may also be mandated by regulators. Airlines currently source position data from aggregators like FR24 and Flightaware which blend ADS-B sources with real-time ANSP data, or from service providers using ACARS (ADS-C) feeds.

As ve3id mentioned, Flightaware is an Aireon partner so they will have first mover advantage of this new service, with Qatar Airways set to become their launch customer.

By the way Aireon is majority owned by NAV CANADA.

[India Four Two]

I'm interested in the mechanics of how ten satellites are launched into presumably different orbits.

Can anyone point me to a link ?

[peekay4]

All of the satellites were launched to the same temporary orbit (parking orbit) via a special dispensers which released one satellite every 100 seconds.

Over the next several weeks, the satellites will undergo qualifications at the temporary orbit. Afterwards each satellite will be moved higher to various final orbits -- replacing existing Iridium satellites on a one-to-one basis. There's enough propulsion in the satellites to move them in and out of (and maintain position at) various orbital positions.

Eventually they will also place spare satellites at parking orbits.

[ion_berkley]

Space based ADS-B tracking was already demonstrated in the fall of 2015 by a small Danish company on a very modest Cubesat called GOMX-3 launched from the International Space Station. It worked pretty darned well and returned good data until it reentered about a year later. Expect global ADS-B coverage to be a commodity in very short time, and costs to be very reasonable.

As a curve ball broadly inline with the same topic, folks are also experimenting with very small floating solar powered ADS-B receivers with similar goals.

[India Four Two]

peekay4,

Thanks very much for that useful information. When the satellites are boosted out of the parking orbit, is the orbital inclination changed at the same time?

[peekay4]

No they were placed in the correct inclination (86.4 degrees for all Iridium satellites). Changing the inclination would require too much propulsion. Right now all the satellites would be close together in the same orbital plane -- one following another -- in a lower orbit than final.

The ascending node of satellites in prograde orbit drift westward. Boosting one satellite to a higher orbit also means it will drift slower, i.e., it "slows down" vs. the rest. In this way they can start evenly "spacing out" the satellites around the earth (although they still will be in the same orbital plane).

The next bunch of satellites will be on the same 86.4 degree inclination but on a different orbital plane. By repeating this process they can create a mesh of satellites spaced out in different orbital planes.

[Grumpi]

Almost, but not quite. They can also move satellites to different orbital planes.

They just launched their 10 satellites into the one orbit which is in the worst shape ("orbital plane 6"): it already has a small gap, and no spares left. In this case, eight are supposed to stay there and will be spread out by boosting them out of their current lower orbit into the higher one at appropriate times. Two will be moved to the adjacent orbital plane 5.

In the end, I think eleven satellites each (plus spares) are supposed to go into each of the six orbits (planes), so with seven launches lifting chunks of 10, that wouldn't work if they could not move between orbits.

[peekay4]

Almost, but not quite. They can also move satellites to different orbital planes.
Yes, of course. The question was about changing the orbital inclination between the parking orbit and the final one. Both orbits will have the same inclination.

Significant changes to the inclination require a huge amount of propellant (unless we're willing to wait forever) so it's best to place the satellites in the correct inclination to start with.

Changing the orbital plane can be done by making only a tiny, temporary change to the inclination. Changing the inclination isn't the aim -- typically the change is only a fraction of a degree -- just enough to very slowly drift the satellite towards the new plane. It can take a year before the satellite arrives at an adjacent plane.

Two will be moved to the adjacent orbital plane 5.
Thanks, I hadn't read that. Looks like the next launch will go for plane 3. Do you know how many drifters will be on the next launch?

[Nemrytter]

Space based ADS-B tracking was already demonstrated in the fall of 2015 by a small Danish company on a very modest Cubesat called GOMX-3 launched from the International Space Station. It was actually demonstrated prior to that using a German Space Agency (DLR) sensor aboard PROBA-V (mid-2013).

[India Four Two]

Grumpi and peekay4,

Thanks a lot for the detailed information. I was aware of the energy implications of changing inclinations, which is why I asked the question. Where can I find more information about launches and orbits?

[peekay4]

Depending on your interests there are some great online courses (all free!) on edX:

1. MITx 16.00x Introduction to Aerospace Engineering (https://www.edx.org/course/introduction-aerospace-engineering-mitx-16-00x-0) is a great introductory course by MIT professor and NASA veteran astronaut Jeff Hoffman. The course has ended but you can still enroll and access all of the course content. Hard math parts optional; many students / enthusiasts simply skip them, and you can freely jump around to topics which interest you (e.g., Orbital Mechanics).

2. UC3M The Conquest of Space (https://www.edx.org/course/conquest-space-space-exploration-rocket-uc3mx-bia-1x-0) is another free intro course blending the history of spaceflight (from the V2, sputnik, Apollo to present day) along with more technical topics. The next class starts Feb 28.

3. EPFL Space Mission Design and Operations (https://www.edx.org/course/space-mission-design-operations-epflx-ee585x-0) is a more rigorous course taught by veteran ESA astronaut Claude Nicollier. Orbital mechanics are explored at length. If you still remember your undergrad level physics & calculus, this may be the course to take. The next running of the course starts Feb 22.

[India Four Two]

Great stuff. I'll review Number 1 and signup for Number 3. I use physics and calculus in my day job, so I think I can cope. ;)

[Ian W]

What has not yet been demonstrated is the discrimination of ADS-B transmissions when congested areas are in the hosted payload footprint. As the ADS-B mandates apply to more aircraft and GA move to 1090MHz from DUAT, frequency congestion that is a problem now even at aircraft levels will become worse. In a 3000 mile footprint there can be a lot of transmissions to discriminate.

[peekay4]

The Aireon system is really designed for remote / oceanic routes where the traffic density will always be relatively low, as compared to high density terminal areas like ORD or ATL. So I don't think discrimination will be an issue for the satellites over these routes.

A bigger issue than density is total system capacity -- I believe Aireon can track about 10,000 aircraft simultaneously. But these days (on a busy day) we already have more than 10,000 aircraft flying at one time, and it's increasing every day. So that tells me Aireon will not try to track all aircraft world-wide, but will function as a supplement to existing & future ADS-B ground receiver infrastructure.

Mind you ADS-B congestion is a big issue, just not for these satellites over remote / oceanic areas.

[mmurray]

Interesting stuff. I assume they have a way of bringing the old Iridium satellites down to burn up ?

[peekay4]

Interesting stuff. I assume they have a way of bringing the old Iridium satellites down to burn up ?

Yes, mostly. The plan was to de-orbit the old satellites by moving them into a low elliptical orbit (250 km at the perigee). The atmospheric drag at this altitude will eventually slow them enough that most will re-enter the atmosphere and burn up within several months.

The problem is that many of these old satellites are very nearly out of fuel -- because of delays and the need to quickly switch them to different orbital planes than originally intended.

So instead Iridium is proposing to place these satellites into an elliptical orbit with 600 km perigee. From this altitude it might take up to 10 years before the satellites will re-enter the atmosphere.

[Grumpi]

Changing the orbital plane can be done by making only a tiny, temporary change to the inclination. Changing the inclination isn't the aim -- typically the change is only a fraction of a degree -- just enough to very slowly drift the satellite towards the new plane. It can take a year before the satellite arrives at an adjacent plane.

True, switching only the plane I guess can be done with extremely small inclination changes if there is enough time to wait for the "drift".




Thanks, I hadn't read that. Looks like the next launch will go for plane 3. Do you know how many drifters will be on the next launch?
No, and for the last launch it was only published after the launch. I anyway suspect that they did not finalize that yet for the next launch, especially since they have a several month testing period before the second batch. I would assume that based on what they find, they will keep optimizing the overall slotting until very shortly before the launch, and then re-evaluate depending on how precise the orbit insertion by the rocket was.

There is a website about the configuration here:
Iridium Constellation Status (http://www.rod.sladen.org.uk/iridium.htm)

[Geosync]

In a former life I built GEO comm sats as a lead technician coming from the aviation AME world, but literally all of it was OJT mechanical and electrical work, and we were not taught any of the science-y stuff. I had to go seek it out on my time. This book is fantastic for non- math/engineering crowd-

How Spacecraft Fly: Spaceflight Without Formulae
Swinerd, Graham

Discusses rockets, orbital mechanics, satellites, space systems design, etc. A must-have for anyone interested in the space portion of "aerospace".

[ex-EGLL]

Global ADSB is a promising service, but it is only part of the system. The primary intent (I believe) is to provide surveillance over remote areas. Remote areas, and in particular oceans, have very little comm capability. If separation is to be reduced in these areas then reliable communications is going to be needed. Theoretically it may be possible to drop to 5nm over the ocean, but not with HF Voice. CPDLC is a possibility, but I can't see that working with minimum separation. Is there anything in the works fo communications systems to work in conjunction with these satellites?

[Roger Greendeck]

Between CPDLC, TCAS, and air to air VHF you'd think there are enough ways to communicate to allow safe 5nm spacing in oceanic airspace if the ADS-B coverage works. Crossing traffic would be more of an issue but aircraft on the same route should be fine if assigned a Mach number rather than allowing slight variations as happens now.

[compressor stall]

Peekay - do you have any historical data on the orbit of the parked satellites whilst they undergo checks? I ask as the other night I saw a satellite appear about 40° altitude and move downwards to about 25° altitude and disappear. Then another did the same thing about a minute or so later. Then another. We saw six do this, all the same and with similar spacing, and it's been bugging me what the hell they were!

[wiggy]

Sounds odd...I'm not sure you end up with "aged" satellites effectively clustered like that, even in some form of parking orbit (would there be any point?).

Isn't it more likely "new" satellites distributed from a single launcher/bus might appear grouped initially (genuine question for those in the know)

Roughly where were you, what was the azimuth, what sort of spacing are we talking about?

[ChickenHouse]

It'll be interesting to see how they deal with data protection issues.

[compressor stall]

Wiggy - Location S37.8E144.9 (Melbourne CBD, Myer Music Bowl)
First one noticed at 17 01 27 1057UTC (there may have been more prior)
Object appeared in the north, directly below Orion. Each about almost as bright as Betelgeuse and satellite like in appearance (i.e. just a moving star)

Just plotted it on iPad app.
All appeared at about 35° altitude and tracked directly down to about 18° altitude. Azimuth about 010°

None visible at the same time, the next one appeared about 30 seconds after the previous one had faded out. They were moving so slowly that it was hard to tell at first if they were moving. It probably took about one minute from appearing to disappearing.

I was in the middle of a crowd at an outdoor concert so more accurate observations were not possible. My wife saw them as well, independently of me and remarked about them, unprompted.

Yes - was thinking that they were the new ones waiting in line to be boosted up. I can't find any data on them in Heavens-above or similar.

[SATCOS WHIPPING BOY]

Have I misunderstood the capacity of the Aireon system? It says 10,000 aircraft globally; a quick check just now on flightradar has 9000+ and this excludes most of Africa, China, Russia.

[peekay4]

Hi compressor stall, it is possible that you indeed saw the Iridium Next satellites.

According to (approximate) calculations for that date from your location, Iridium 114 would have been at 36° elevation, 14° azimuth at 10:57 UTC and dropping to 22° elevation, 11° azimuth a minute later -- matching your observations. Many of the other Iridium Next satellites would have been nearby.

You can compute past or predicted positions by using an app or online calculator tool that accept "Two Line Element" (TLE) observation data published by the US Space Surveillance Network. Here's an example TLE for Iridium 114:

IRIDIUM 114 [+]
1 41923U 17003G 17030.22607686 .00000357 00000-0 39151-4 0 9996
2 41923 86.6609 79.6394 0011490 177.2547 182.8728 14.84387795 2297

This particular observation was made at Jan 30 00:25 UTC so calculations beyond a several days from this date wouldn't be too accurate.

Link: Iridium NEXT TLEs from Celestrak (https://www.celestrak.com/NORAD/elements/iridium-NEXT.txt).

[compressor stall]

Thanks peekay. Great data, and good to know my obs were pretty accurate given I was in the middle of a concert crowd!

I'd been looking for historical data, and will folllow up on the links you provided. Cheers.

[Ian W]

Between CPDLC, TCAS, and air to air VHF you'd think there are enough ways to communicate to allow safe 5nm spacing in oceanic airspace if the ADS-B coverage works. Crossing traffic would be more of an issue but aircraft on the same route should be fine if assigned a Mach number rather than allowing slight variations as happens now.

The ADS-B capability is in a hosted payload on Iridium Next satellites which are primarily a fully global communications network. So every aircraft that can be seen by Iridium hosted payload could have one or more broadband comms links including voice comms.

Welcome to the brave new world of ubiquitous communications

[Max Angle]

Unless the new satellites have the same antenna design, unlikely I suspect, it will be the end of "iridium flares". The antennas of the current units have a highly polished surface that produces a bright flash of light when the sun shines on it, this can be seen at night as a brief very bright star shining in the night sky. Seen quite a few over the years and there are various websites that offer a prediction of where and when.

[wiggy]

Thanks peekay.

Max-there are various websites that offer a prediction of where and when.

Indeed the previously mentioned "Heavens above" is a good 'un.

Heavens-Above (http://www.heavens-above.com/)

For the unitiated I'd say if you're looking for the bright iridium flashes using that software (and no doubt all the others) it's worth making the effort to put a really accurate position in, rather than a generic "nearest town" or even village. it is interesting to see how narrow the iridium flash ground tracks are and a handful of Kms of position error can make a big difference between a predicted event being a "wow" or a "what, that's it? but you told me.....".

[ve3id]

And some said it was not possible:

https://flightaware.com/news/article/Malaysia-Airlines-enlists-SITAONAIR-Aireon-and-FlightAware-for-100-global-flight-tracking/278

[wiggy]

Did they? I know there were lots of arguments about the feasibility of continuous downloading of FDR data via satellite, but this is ADS-B and whilst it offers an improvement in coverage as the report says:

No new avionics or modifications are needed for aircraft to take advantage of this service.

[ve3id]

Yes they did! It was assumed that the data would be decoded only by land stations, and therefore only over and LOS from land. I engaged in a discussion with someone who said it would be useless in Northern Canada since there would be too many ground stations needed!

Of course, satellites can pick up and process position squints quite nicely since they have a small payload.

[DaveReidUK]

That strikes me as a somewhat circular argument.

[Airbubba]

I believe several carriers are already doing satellite based ADS-B tracking using existing platforms.

For example, on Inmarsat (at the bottom of the Other Tracking Info tab):

http://sat-global.adsbexchange.com/VirtualRadar/desktop.html

[wiggy]

Yes they did! It was assumed that the data would be decoded only by land stations, and therefore only over and LOS from land. I engaged in a discussion with someone who said it would be useless in Northern Canada since there would be too many ground stations needed!

OK I see what you mean, I'm not sure who you were discussing it with but the concept of ADS-B via satellite has been around and progressing for a few years, anyone who said it wasn't possible was missinformed. This 4 year old pdf might be of interest.

https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/ato_intl/documents/cross_polar/CPWG16/CPWG16_PPT09_Satellite_Based_ADSB_December2013.pdf

I think Malaysian and their service providers are claiming this is groundbraking because they are saying they are the first airline to tap in to it to have full time, real time data, with, it seems possibly an alerting function at head office, rather than ADS-B to satellite being a radical new concept...

[Jet Jockey A4]

Our aircrafts have been tracked around the world in real time for as long as I can remember through Data link via VHF and satellite.

[underfire]

The 'system' concept is not new, but implementation is. Enough sats had to be put in place to make the coverage work, and even now, I dont believe the 88 have been launched.
Inmarsat has been marketing like crazy to get this service going.
A few things, the sat coverage, but the expense is what has really kept this from much wider usage, the airlines just dont want to pay for the service.
The position data sent thru the Ku band IFE systems has become much more popular, provides much more data, and is already costed in.

If there was ADSB-IN, then the aircraft could be a relay network in themselves....I think FR 24 is working on that.

[ozon]

Attention, there are a lot of "will" in the article regarding the online tracking, with a resolution of 1 minute, of Malaysian planes. The text just says the country will be the first to implement such a revolutionary system, not that it has already tested it. The Aireon group of satellites it not yet operational. It will be in 2018.

KUALA LUMPUR and LONDON, April 18 2017 – SITAONAIR, Aireon and FlightAware today announced that Malaysia Airlines will be the first SITAONAIR airline customer to benefit from a revolutionary flight-tracking partnership. Under the agreement, all Malaysia Airlines aircraft will have access to minute-by-minute, 100% global, flight-tracking data, delivered by SITAONAIR’s AIRCOM® FlightTracker. ...
The Aireon service will be operational in 2018, shortly after the completion of the Iridium NEXT satellite constellation.
Source: https://flightaware.com/news/article/Malaysia-Airlines-enlists-SITAONAIR-Aireon-and-FlightAware-for-100-global-flight-tracking/278

We have to wait and see.
We still do not know if such a tracking facility really works.

Even if Malaysia, which has a maximum of a few dozens planes in the air at a given time, will get the online position on the map for all their aircrafts, question still remain if the Aireon can be scaled up and became of real use for all the few thousands planes flying in the world at each moment.

[ozon]

"Iridium is currently developing, and is expected to launch during 2017 and 2018, Iridium NEXT, a second-generation worldwide network of telecommunications satellites, consisting of 66 satellites"
Source: https://en.wikipedia.org/wiki/Iridium_satellite_constellation

Aireon is based on Iridium NEXT.
See: https://aireon.com/services/global-air-traffic-surveillance/

[ozon]

I am afraid there will be a lot of false alarms that will render the new tracking system impractical. I mean a few times a week the Aireon’s technology, based on the Iridium NEXT constellation of satellites, will trigger alarms for airliners that have just disappeared in the middle of the ocean when in reality nothing serious happened. Expensive rescue mission will be initiated just to be canceled after a few hours.

[DaveReidUK]

Do you have any evidence (at all) to actually back up that assertion?

If so, would you like to share it?

[ozon]

This is about an incident when a false plane was artificially created and the presence of such a phantom negatively impacted, for 30 minutes, real flights.

"FAA Cautions about Transponder and ADS-B Testing
by Gordon Gilbert
February 27, 2017, 9:43 AM

Incidents of improper ground testing of transponder and ADS-B OUT equipment have resulted in false position information, including simulated altitude, being transmitted from the test aircraft and received by aircraft in flight. As a result of these reports, the FAA has issued a Safety Alert For Operators to advise them of the problem and recommend solutions.

According to the FAA, in at least one instance, an ADS-B OUT system ground test created a false airborne target that generated a TCAS resolution advisory (RA) to an airliner on approach. “Pilot reaction to this RA required unnecessary maneuvering in congested airspace and initiated ATC re-sequencing actions that affected multiple aircraft and negatively impacted operations in the area for about 30 minutes.”

The FAA advises repair stations and maintenance personnel performing transponder and ADS-B systems testing to evaluate the adequacy of their methods and adhere to proper test procedures, including antenna shielding, to prevent propagation of test signals that could affect ATC operations or airborne aircraft. Theagency also recommends that maintenance personnel be aware of any local requirements to alert ATC of impending testing and review guidance contained in relevant advisory circulars."

FAA Cautions about Transponder and ADS-B Testing | Aerospace News: Aviation International News (http://www.ainonline.com/aviation-news/aerospace/2017-02-27/faa-cautions-about-transponder-and-ads-b-testing)

I have not found yet an example of rescue mission triggered by a plane that apparently disappeared in the middle of the ocean. I am still searching for such an incident.

Anyway, ADS-B is vulnerable to low cost jammers:
see: https://www.researchgate.net/publication/274632775_ADS-B_vulnerability_to_low_cost_jammers_Risk_assessment_and_poss ible_solutions