Iridium NEXT

With the original constellation of satellites nearing the end of their life, Iridium announced its vision in February 2007 for the next generation of Iridium satellites.

Known as Iridium Next, the new Iridium satellite system promises not only to replace the existing constellation of satellites, but Iridium Next also incorporates many new features. Although it would be possible to provide a simple replacement programme for the existing Iridium satellites, it has been decided that Iridium Next will incorporate new technology to enable the system to move forward and keep up with the enhanced requirements expected by many users today.

Accordingly the new system will incorporate these basic functions and following features:

• Backward compatibility with existing Iridium systems
• Full global coverage as before, including the polar areas not accessible to Geostationary satellites
• Low earth orbits enabling low power phones to be used.
• End to end IP technology
• Additional bandwidth capability to allow users more flexibility
• Incorporation of Earth imaging and other secondary payloads – thereby providing additional functionality to further utilise the satellites
• Ability to provide data links to other space based payloads

It is planned to replace the existing Iridium satellites so that a seamless upgrade can be effected.

History of Iridium satellite system

The concept of the Iridium satellite phone system arose before cellular telecommunications systems had been globally deployed in the way they are today. It was therefore anticipated that a phone system offering global coverage would be of great commercial value.

To achieve the goal, Iridium SSC was set up, with Motorola providing the technology and much of the finance. The system gained its name from the fact that originally 77 satellites were planned to orbit the Earth. This had a strong similarity to a nucleus with 77 orbiting electrons – a description that fits the element Iridium.

The satellite system was completed in may 1998, but some trails and commissioning were then required. The Iridium communications service itself was launched on 1st November 1998 with a call made by the then Vice President of the USA, AL Gore.

Despite the successful technical launch of the system, the uptake was very much slower than anticipated. This was attributed to the fact that the deployment of cellular telecommunications systems, especially using GSM was much faster than had originally been anticipated. With roaming features, users could take their phones to many countries and make calls cheaper than they could over the Iridium system. Also there was a massive initial cost for building and launching all the satellites. Accordingly Iridium SSC entered Chapter 11 bankruptcy on 13 August 1999.

Initially no buyers were found for the company and it was anticipated that all the satellites would need to be de-orbited so that they would not be a danger when they re-entered the atmosphere. During the period that discussions about this were ongoing a set of private investors re-launched the company as Iridium Satellite LLC and they restarted the service in 2001.

The service was obviously more expensive than cellular systems and it was therefore used for specialist applications, especially in areas where no cellular coverage was available. For example rescue services, missions to remote areas of the globe, military, etc found the service useful.

With satellites becoming older, some have failed. These have been replaced with in-orbit spares. It takes some days for these replacement satellites to be moved into service, but with the number of satellites in orbit, service is only marginally degraded. Examples of replacements have occurred at various times, e.g. Iridium satellite 28 failed in July 2008 and was replaced by Iridium satellite 95.Another incident took place in 2009. At 16.56 UTC on 10 February 2009, an Iridium satellite (satellite 33) and Kosmos-2251, an out of service Russian satellite collided. Although a major collision creating large amounts of space debris, it was be replaced by a spare satellite already in orbit. This was completed during March 2009.

Summary

The Iridium satellite system offers many advantages and is currently used by many people. This satellite phone system offers full global coverage for voice and data (albeit at a low rate). It is also certified for airborne use and along with many other roles, the Iridium satellite phone system is able provide a useful service to many.

References

Poole, I. (n.d.). Iridium satellite technology, theory and frequency bands. Retrieved June 01, 2016, from https://www.radio- electronics.com/info/satellite/communications-systems/iridium-theory-history-technology-frequency.php