Bill Schweber

This worldwide satellite-based communications system went from dream to reality in a decade but quickly failed in the market; its revival took persistence and luck, plus a new customer base.

Of course, there were also significant technological advances required in many areas, including designing and building longer-life electronics despite the unavoidable effects of space radiation on electronics. While the life of these electronic components in this environment is a function of the specific component and technology as well as orbit height (or space path), a typical figure can be as little as a few years or up to about ten years.

One way to deal with the effect of radiation is to use radiation-hardened (rad-hard) devices. Component vendors have developed various sophisticated process techniques to provide this performance. However, such devices are generally too expensive for the commercial world in which these global systems compete, and the availability of these devices in quantity was uneven. Also, many of the desired and needed latest generation ICs were unavailable as rad-hard components, or the qualification period for these special devices is too long for them to be competitive.

(Note that the situation is changing due to the widespread use of LEO satellites, SpaceCube satellites, military links, and more, resulting in more vendors are offering space-qualified, rad-hard qualified components, but that was not the case for Iridium’s designers.)

Designers of the Iridium satellites used a combination of techniques to overcome these problems.

• Using commercial ICs that have a few extra process steps added, which adds some rad-hard characteristics at a relatively low incremental cost.
• Using circuit design with extra guardbands and tolerancing to allow for parametric drift.
• Adding redundancy, error detection and correction, and resets to accommodate hard and soft failures.
• Selectively using tungsten/copper radiation shielding reduces the electron (but not the proton) aspect of radiation but adds a weight penalty.
• Acknowledging that radiation will limit a satellite’s operating lifetime and, therefore, putting standby spares in orbit and planning to launch new satellites regularly.

The original clusters of Iridium satellites performed remarkably well (three times past its original life expectancy), and all were finally replaced in January 2019 with a next-generation fleet – a real testament to their design integrity. Called the “Next Fleet” satellites, each weighs1875 pounds/850 kg, and France-based Thales Alenia Space built all in an Arizona facility (Figure 1) (Motorola built the original Iridium satellites, also in Arizona).

There is some irony or justice here: SpaceX launched these Iridium replacements, and it was Iridium’s concept and efforts which paved the way for adopting mass production and launching of large clusters of SpaceX/StarLink LEO satellites – which may even soon compete with Iridium, and SpaceX did not even exist during the Iridium project’s initial deployment.

Not the only player now

The Iridium system is not the only one which provides some degree of worldwide satellite-based communication for voice and data. Competitors include Globalstar Inmarsat and Thuraya (plus the possibility of a SpaceX/Starlink system):

Globalstar was created from a section of Ford Aerospace in 1991 and works closely with Qualcomm for components and technology. The system uses an LEO satellite constellation consisting of 48 active satellites, placed in orbit about 900 miles in space. Unlike Iridium, which uses the satellites as orbiting MTSOs, Globalstar uses a less complex technique called bent-pipe. Still, a satellite always needs to have both the handset and the base station in sight. Thus, there is no coverage over the Earth’s poles as the satellites do not illuminate those areas.

Thuraya is a large-footprint regional network based in the United Arab Emirates which uses two Boeing-built geosynchronous satellites to provide mobile coverage to more than 110 countries in Europe, the Middle East, North, Central, and East Africa, Asia, and Australia, but not the Western Hemisphere or the poles (Figure 2). However, the phones also incorporate standard cell-phone technology, so conventional cell coverage is worldwide as long as there is a cell system in range. The longer satellite path link means a weaker signal and thus less-consistent service, while the geosynchronous orbit incurs a much longer path-length propagation delay, which can be a problem.

Inmarsat originated from the International Maritime Satellite Organization (INMARSAT), at the request of the International Maritime Organization (IMO) – the United Nation’s maritime body –  but is now a private UK-based company. It uses thirteen geostationary telecommunications satellites which operate in subgroups to provide three levels of footprint and performance: global beam coverage from latitudes of −82⁰ to +82⁰; regional spot beam coverage which operates with significantly smaller antennas; and narrow spot beam coverage (about several hundred kilometers in diameter) via three of its satellites and which can use even smaller antenna while supporting much higher data rates.

Conclusion

Looking back at satellites’ earliest use for communication, they were envisioned only as relay points in space between large, land-based dish antennas. Low-earth orbit satellites provided only sporadic coverage and used small but fast-tracking dish antennas to follow the LEO satellite. In contrast, geostationary satellites provided a constant link and were supported by much larger but relatively fixed dish antennas.  In just a few decades, the technology has advanced to where true worldwide coverage is available for voice and data using a convenient handset and no dish antenna. No single technology advance made this possible, but the Iridium system showed what could be done when personal energy, radical innovation, commitment, personal connections, money were focused on making technical “dreams” into reality.

EE World Content

Iridium Satellite Connectivity Added to Versatile ConnectPort X5 R Rugged Gateway
DeLorme Unveils Plans for Iridium-Based Two-Way Satellite Communicator
Basics of GPS receivers
GPS, Part 2: Implementation
GPS, Part 1: Basic principles

External References

1. “Eccentric Orbits: The Iridium Story,” John Bloom, Atlantic Monthly Press, 2016.
2. “Iridium Will Host Science Payloads,” IEEE Spectrum, Nov. 30, 2009
3. “The Collision of Iridium 33 and Cosmos 2251,”Aerospace, December 10, 2015
4. “A guide to useful, useless, official and unofficial Iridium websites”
5. “The Rise and Fall and Rise of Iridium,” Air & Space Magazine, September 2004
6. “Iridium ends legacy satellite service, switches all traffic to Next fleet,” Space News, February 2019
7. “SpaceX completes Iridium Next constellation,” Space News, January 11, 2019
8. “Iridium starting to deorbit legacy satellites as Next constellation comes online,” Space News, May 1, 2017
9. “Elon Musk’s Ambitious Communication Project to Ring Earth with 40,000 Satellites,” News18, Sept 19, 2020
10. Wikipedia, “Starlink”
11. “Starlink: SpaceX’s satellite internet project,” com, January 17, 2020
12. Thales Group, “Happy Birthday Iridium Next,” January 14, 2020
13. PhoneIsMobile, “Iridium Satellite Phone”
14. Wikipedia, “Iridium satellite constellation”
15. Wikipedia, “Inmarsat”
16. Wikipedia, “Thuraya”
17. Wikipedia, “Globalstar

This worldwide satellite-based communications system went from dream to reality in a decade but quickly failed in the market; its revival took persistence and luck, plus a new customer base.

Iridium’s launch, crash, and nearly burn (literally)

The Iridium communications service was initiated on November 1, 1998, with a call by then-Vice President Al Gore. After several months of working through technical issues, the system actually worked fairly well and met most objectives. Potential users were impressed, and the initially skeptical technology community was impressed that Iridium went from an idea to a fully operational system in a little over a decade.

On the business side, though, things were dismal. Instead of tens of thousands of users willing to pay thousands of dollars for a phone and about $10/minute for a call, the system only signed up a few hundred. Among the reasons is that the anticipated market of world-wide business travelers never materialized, due to the cost and size of the handsets and calls, the fact that most such travelers were in areas that had cellular service, and an Iridium technical weakness that the caller had to be outside to “see” the satellite. In contrast, conventional cell calls could be done from inside most buildings.

Iridium Satellite LLC (the official name) went into Chapter 11 bankruptcy in less than a year. What took a little over a decade to create and implement took just nine months to crash figuratively, and it seemed the literal crash come soon thereafter. Motorola would not tolerate the $200 million/month ongoing operating costs with no prospect of eventual turnaround; simultaneously, the gateway owners demanded make-good on their expected revenue, and the system needed planning for additional satellite launches as spares.

Motorola said the solution to this never-ending financial drain was easy and clear: write off the loss, and kill the system and shut it down, which included de-orbiting the satellites by directing them into lower orbits where they would soon begin reentry and burn up. The picture was both bleak and apparently hopeless.

Over the next few months, Motorola issued several “firm and final deadlines” saying if the system did not find a buyer by a specified, very close date, the satellites would be instructed to de-orbit with 48 hours of that deadline; each time, the deadline was put off due to pleading from a small group of tireless Iridium proponents who sought new investment partners in the $20 to $100 million range around the world, including poor African countries who wanted both the connectivity access and prestige and their portion of the ongoing gateway revenue.

Back from the near-dead

A break came for the unlikeliest of places when a New York Times article on the Iridium situation mentioned that some of the satellites might not burn up completely, and some debris might land on inhabited areas or even hit someone. Suddenly, legal liability became the dominant issue preventing issuing the de-orbit command, with concerns about who would have that liability, who would insure against it, and how that would happen. This potential debris issue – and it was a real but actually quite a minor possibility based on previous satellite burn-ups – became the delaying element which kept Motorola from issuing the formal de-orbit order and bought time for more tries at survival.

Eventually, after countless issued and withdrawn deadlines and hunts for funding, the remaining Iridium team, led by Dan Colussy, a retired CEO of Pan, heard about Motorola’s plans and decided he would buy Iridium. After considerable effort, he was able to pull together financing from private investors and the US Department of Defense (DoD), who became convinced after many meetings and PowerPoint presentations that Iridium was a valuable and irreplaceable resource for the military. Critical to this decision was the reality that the Colussy’s Iridium team – mostly aerospace industry veterans and former DoD insiders – knew the right people to talk to, or at least knew people who could help them get meetings with the key influencers and decision-makers at the Pentagon.

The DoD funding came from a “special fund,” used for special projects and did not require any formal tender or bidding but is instead reserved for projects deemed critical for national security. Potential Iridium competitors such as Globalstar protested, but these were denied under “critical to national security” rules. (Note that Globalstar’s proposed system was technically far less advanced, as it used the satellites only as relay points from earth-satellite-earth connections. This is known in the industry as a “bent pipe” arrangement and may require several “hops” between callers; in contrast, the Iridium system used the satellites as a sophisticated meshed network with far less propagation delay since call routing was done dynamically by the mesh itself.)

The assets of the bankrupt company, Iridium Satellite LLC, were purchased for $35 million (compared to a cost of billions) by the newly created owner, Iridium Communications, Inc., a publicly-traded (NASDAQ) company. All the gateways have been shut down except for a commercial one based in Tempe, Arizona, and a DoD one in Hawaii.

But the story does not end there. Like a fairy tale or the legendary Phoenix bird of many cultures (known for its ability to live for many years before dying in a burst of flames, only to be reborn from the ashes), Iridium was reconstructed, rebuilt, and restarted. As of 2019 company has 782,000 subscribers, with 72,000 of them government subscribers. They have expanded from basic voice service to broadband service for higher-speed data. They are actively working on a full set of 3rd-generation satellites for even higher-speed performance and capacity, at the cost of just under $2 billion. Among the commercial users are oil rigs, ships, desert mining sites, and even Antarctica’s year-round scientific bases.

The next part of this article looks at some of the “big picture” lessons and context of the Iridium project.

EE World Content

Iridium Satellite Connectivity Added to Versatile ConnectPort X5 R Rugged Gateway
DeLorme Unveils Plans for Iridium-Based Two-Way Satellite Communicator
Basics of GPS receivers
GPS, Part 2: Implementation
GPS, Part 1: Basic principles

External References

1. “Eccentric Orbits: The Iridium Story,” John Bloom, Atlantic Monthly Press, 2016.
2. “Iridium Will Host Science Payloads,” IEEE Spectrum, Nov. 30, 2009
3. “The Collision of Iridium 33 and Cosmos 2251,”Aerospace, December 10, 2015
4. “A guide to useful, useless, official and unofficial Iridium websites”
5. “The Rise and Fall and Rise of Iridium,” Air & Space Magazine, September 2004
6. “Iridium ends legacy satellite service, switches all traffic to Next fleet,” Space News, February 2019
7. “SpaceX completes Iridium Next constellation,” Space News, January 11, 2019
8. “Iridium starting to deorbit legacy satellites as Next constellation comes online,” Space News, May 1, 2017
9. “Elon Musk’s Ambitious Communication Project to Ring Earth with 40,000 Satellites,” News18, Sept 19, 2020
10. Wikipedia, “Starlink”
11. “Starlink: SpaceX’s satellite internet project,” com, January 17, 2020
12. Thales Group, “Happy Birthday Iridium Next,” January 14, 2020
13. PhoneIsMobile, “Iridium Satellite Phone”
14. Wikipedia, “Iridium satellite constellation”
15. Wikipedia, “Inmarsat”
16. Wikipedia, “Thuraya”
17. Wikipedia, “Globalstar”

This worldwide satellite-based communications system went from dream to reality in a decade but quickly failed in the market; its revival took persistence and luck, plus a new customer base.

The first part of the article explained the inspiration and rationale for the Iridium system. Three major elements were required to make the Iridium concept and dream – and it was truly a dream – into reality:

1) A global constellation of 66 satellites (plus about half a dozen or more “spares”), but not in the usual geosynchronous orbits or even low-altitude, low- propagation-delay orbits. Instead, polar orbits would be used for 100% Earth coverage (Figure 1). The original calculations showed that 77 such satellites would be needed (plus spares), so the system was named after element 77 on the periodic table (subsequent analysis showed that just 66 satellites were needed, but the re-naming it Dysprosium for the 66^th element was rejected). The satellites were arranged in six orbital planes of 11 satellites each and inclined at 86.4°, just a few degrees off a perfect north-south axis; these orbital planes criss-cross at each pole. At the height of 485 miles (781 km), each satellite orbits every 100 minutes, with a round-trip Earth-satellite link propagation delay of 5 msec, which is very acceptable for two-way speech.

These satellites were not just simple connecting points for one-hop, Earth-based connections between users. Instead, they were orbiting MTSOs which could dynamically link and unlink via the Ka microwave band (26.5 to 40 GHz) to any of four adjacent satellites: the ones immediately before and after in the same orbital plane, as well as the closest ones in adjacent planes (Figure 2). A call in progress might go through one, two, or more satellites and be handed off as the satellites orbited; these handoffs would occur every minute for a given call connection. As a result, a call’s link delay was just the 5 msec plus the satellite-to-satellite link delay of another few milliseconds, far less than the geosynchronous link with its 240-msec hop delay.

The fabric topology and software needed to make this work were unlike anything orbited. The processing and routing demands were stringent, yet available power was limited to the solar panels. The first-generation designs measured about 4 meters by 1.8 meters, weighed 689 kilograms (1,519 lb) with innovative antennas for communicating with ground stations as well as adjacent satellites (Figure 3). Due to the low orbits, the satellites were in Earth-circling radiation belts and needed radiation-hardened components, yet still would have reduced life.

2) Satellites alone were only part of the overall plan. Earth-based stations called gateways were needed to link to the 66 satellites and to each other, to complete the system management and fabric, and also link to the terrestrial phone network. These gateways (there were roughly two dozen), would be located around the globe, in countries that had a technology base and some that had nearly none.

The software needed to link these gateways and manage them in real-time, along with the actual links between them, was another high-risk challenge. Communication between satellites and earth stations used 30 GHz for the uplink and 20 GHz for the downlink. Some gateways were owned by the hosting country, while others were owned and operated by a private licensee in that country, with the government’s official approval. Overall system management was done by a dedicated Satellite Network Operating Center (SNOC) facility—also a major undertaking.

3) Finally, handsets had to be provided so users could actually contact the satellite constellation. Motorola contracted with several handset vendors, including Kyocera and their own handset group, to design and build these. The first units were relatively large and bulky (3 pounds), and priced at several thousand dollars, and subsequent units have shrunk considerably in size, weight and cost, and are now close but not quite to the parameters of concurrent, mass-market standard cell phones (Figure 4). Iridium phones have an unusual external antenna, which is a technical necessity for linking to the satellites. Some of the phones can even connect to a small, separate, domed-shaped antenna for a better signal.

Making it happen

The technical challenges across all three aspects – satellites, gateways, and handsets – were enormous, obviously. The design teams had to devise new topologies for these unique mesh networks, new algorithms for call handling and handoff, new RF designs including antennas, and make it all fit into the modest-size package.

Unlike conventional communications satellites, where each one is uniquely designed, built, and launched, a large number of Iridium satellites mandated a “mass production” approach. The idea was to build identical satellites in clusters of ten or more while only incorporating any changes in subsequent batches if there was a demonstrable benefit. Thus, Iridium standardized the satellites to the extent possible, which was a radical approach.

The launches would be done from sites across the globe, including China, French Guyana, and the Soviet Union (before the breakup), using contracted services. A typical rocket would include at least six satellites, and sometimes up to a dozen, to save time and cost. While this provided many operational advantages, it also added risk, as when a rocket exploded or failed to orbit. The entire multi-satellite payload was lost (which happened several times).

While building identical units is not “mass-production” in the consumer-product world, it very much was for satellites, which, until that point, were unique, no-two-alike units. Note that the mass-production concept is now widely used, with the multiple satellite load and launch of hundreds and thousands of relatively small satellites (about 500 pounds/225 kilograms)  in the StarLink system from SpaceX.

The other side of getting Iridium “off the ground” had little to do with technology and everything to do with spectrum assignment, regulatory issues, and global reach. The Motorola-driven Iridium system had to get some specific spectrum allocations from the International Telecommunication Union (ITU – the United Nations specialized agency for information and communication technologies) at its biannual meeting of over 100 countries, and also get license agreements with the countries that would host the gateways. Both allocation and agreements became extremely time-consuming and bureaucratic battles, as countries objected for security, financial, and political reasons.

In the end, what solved both the spectrum and gateway problems was a combination of Motorola’s long-standing relationships with key people in many of the countries, as well as promises and guarantees to gateway operators and their governments (and many rumors of “shady” payments and more). As a highly respected vendor for decades, Motorola’s local agents were able to actually call on key government ministries and officials, get their attention, and work out needed agreements.

The next part describes how Iridium soon failed as a business and how it came back from the nearly dead.

EE World Content

Iridium Satellite Connectivity Added to Versatile ConnectPort X5 R Rugged Gateway
DeLorme Unveils Plans for Iridium-Based Two-Way Satellite Communicator
Basics of GPS receivers
GPS, Part 2: Implementation
GPS, Part 1: Basic principles

External References

1. “Eccentric Orbits: The Iridium Story,” John Bloom, Atlantic Monthly Press, 2016.
2. “Iridium Will Host Science Payloads,” IEEE Spectrum, Nov. 30, 2009
3. “The Collision of Iridium 33 and Cosmos 2251,”Aerospace, December 10, 2015
4. “A guide to useful, useless, official, and unofficial Iridium websites.”
5. “The Rise and Fall and Rise of Iridium,” Air & Space Magazine, September 2004
6. “Iridium ends legacy satellite service, switches all traffic to Next fleet,” Space News, February 2019
7. “SpaceX completes Iridium Next constellation,” Space News, January 11, 2019
8. “Iridium starting to deorbit legacy satellites as Next constellation comes online,” Space News, May 1, 2017
9. “Elon Musk’s Ambitious Communication Project to Ring Earth with 40,000 Satellites,” News18, Sept 19, 2020
10. Wikipedia, “Starlink”
11. “Starlink: SpaceX’s satellite internet project,” com, January 17, 2020
12. Thales Group, “Happy Birthday Iridium Next,” January 14, 2020
13. PhoneIsMobile, “Iridium Satellite Phone”
14. Wikipedia, “Iridium satellite constellation.”
15. Wikipedia, “Inmarsat”
16. Wikipedia, “Thuraya”
17. Wikipedia, “Globalstar”