At 15:31 UTC on January the 11th 2019 an already flown Falcon 9 was the first SpaceX rocket flown in 2019. Launching from Vandenberg Air Force Base in California, it launched ten more Iridium NEXT satellites. The 70 metre high rocket with its 9 merlin 1D engines is the first of 18 expected flights this year for SpaceX. A surprisingly clear day for Vandenberg, the Falcon 9 flew over the Pacific Ocean early in the morning (local time) giving a great view of the launch. The Falcon 9 first stage booster successfully landed back on Earth for a second time, landing on the autonomous drone ship “Just Read the Instructions”.
The booster used for this mission was B1049.2, which had previously flown on Telstar 18V mission, making this the second time this Block 5 first stage has flown. The 1.71 million pounds of thrust took the 9,600 kg payload towards a Polar Low Earth Orbit, like the other Iridium NEXT satellites. The rocket deployed the satellites one at a time over a roughly 15 minute period, around 30 minutes into the flight. Each of the 1,896-pound (860-kilogram) Iridium Next satellites will use their own thrusters to climb into a higher 476-mile-high (780-kilometer) to orbit, where six of the new spacecraft will rendezvous with the last of the old Block 1 satellites.
This mission of ten more upgraded spacecraft has completed the build-out of Iridium’s modernised $3 billion global communications network. They are setting up for the planned debut of new broadband and aircraft tracking services in the coming months. This completes the 75 payloads on eight Falcon 9 missions since January 2017. The idea was to upgrade the old voice and data relay networks currently still in use. Iridium ordered 81 Iridium NEXT satellites from Thales Alenia Space and Northrop Grumman Innovation Systems, which were built in Gilbert, Arizona. Two weeks after the maiden flight of the Falcon 9 in 2010 Iridium announced a nearly $500 million contract for SpaceX to deliver the satellites to orbit. The initial plan was to start launching in 2015, finishing around 2017. Delays pushed by two Falcon 9 problems in 2015 and 2016 pushed the schedule back. In the end only 75 of the planned 81 have been launched, with 6 being flight spares. They could be launched to be additional backups for the system.
The old satellites, that were built by Lockheed Martin had an initial lifespan of 7 years, and have way outlived their planned life. Engineers are currently deactivating the retiring satellites as the new stations arrive in orbit. Most of them have been maneuvered out of orbit to fall back to Earth and burn up in the atmosphere. They have usually gone through a process of “passivation” where the batteries and propellant tanks are drained to minimise chances of them exploding at some point in the future. Iridium satellites have also been a popular sight for astronomers, with “Iridium flares” becoming a commonly used term. It is where reflective parts of a satellite catch a glint from the sun and show up on the ground as a flash, sometimes 5-20 seconds long. They can be as bright as magnitude -8, which is brighter than Venus in the sky. Iridium satellites have been known to be a noticeable cause of these flares, leading to the name “Iridium flares”. The new satellites have a different antenna shape meaning they do not reflect in the same way.
As well as majorly upgraded telecommunications ability the satellites also host a radio receiver for Aireon, an affiliate of Iridium. Aireon work with traffic control authorities in Europe and Canada. The new instrumentation will track air traffic worldwide, including planes travelling outside the range of conventional ground based radar. This completion of the network has allowed the services provided by Aireon to take a big step forward towards starting operations. When airplanes fly out of radar range, pilots are typically instructed to maintain a certain course and altitude, ensuring 30-to-100 miles (about 50-150 km) of separation between aircraft for safety purposes. With real-time global monitoring, those requirements could be relaxed. According to Aireon the certification of the system should be complete by March, allowing operational trials over the North Atlantic.
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