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<\/p>\nSpaceX conducted the fifth launch of its contract with Iridium Communications Friday, deploying ten more satellites to bring Iridium\u2019s next-generation fleet up to a total of fifty satellites in orbit. Falcon 9 lifted off from Vandenberg Air Force Base at 07:13:51 Pacific Daylight Time (14:13 UTC). The launch also saw SpaceX make an unsuccessful attempt to recover half of Falcon 9\u2019s payload fairing.\n<\/p>\n
Friday\u2019s launch was one of eight that SpaceX is conducting for Virginia-based Iridium Communications, to deploy a total of seventy-five Iridium-NEXT satellites into low Earth orbit. SpaceX began deploying the constellation with four launches last year \u2013 the remaining launches will take place in 2018 with Saturday\u2019s the first of the year.<\/p>\n
Iridium Communications specializes in mobile satellite communications. Instead of using a small number of satellites in geostationary orbit, the company operates a large fleet in low Earth orbit \u2013 which relieves its customers of the need to carry around large antennas and results in a lower latency than geostationary communications.<\/p>\n
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Iridium NEXT-5 on the pad \u2013 photo by Jack Beyer for NSF (including lead photo)<\/p>\n
The Iridium constellation was originally developed by Iridium SSC, financed by Motorola, with first-generation satellites deploying between 1997 to 2002. The constellation\u2019s name comes from the chemical element Iridium, which has atomic number 77, as the system was originally expected to require seventy-seven satellites to provide worldwide service. The name was retained after the constellation was redesigned, reducing the minimum number of satellites to 66.<\/p>\n
A drawback of Iridium\u2019s concept was that the constellation required all of its satellites to be in orbit before commercial service could begin \u2013 resulting in high initial outlay. The setup cost of Iridium\u2019s first-generation constellation in the late 1990s was estimated at around five billion US dollars.<\/p>\n<\/p>\n
To get their satellites into orbit as quickly as possible, Iridium employed a varied, global, fleet of rockets: 55 of the satellites were deployed by twelve US Delta II rockets, carrying five satellites each. Russia launched twenty-five via three Proton-K\/DM2 rockets with seven spacecraft aboard, and two dual-satellite launches using Rokot\/Briz-KM vehicles. China\u2019s Chang Zheng 2C\/SD made six launches, deploying a total of twelve spacecraft.<\/p>\n
The cost of building and launching its fleet of satellites, combined with a slower-than-planned uptake from customers, led to Iridium SSC declaring bankruptcy in 1999. Time Magazine described the company\u2019s collapse as one of the \u201cten biggest tech failures of the [\u2026] decade\u201d. A new company, which would become the present-day Iridium Communications, was formed in 2001 and purchased Iridium SSC\u2019s assets \u2013 including the satellites \u2013 at a fraction of their value.<\/p>\n
Space Shuttle models (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n Iridium\u2019s first-generation satellites were built around Lockheed Martin\u2019s LM-700A bus, with a design life of eight years. Between 2002 and early 2017, no further satellites were launched to replenish the constellation. This changed last January when SpaceX deployed the first ten second-generation Iridium-NEXT satellites.<\/p>\n Iridium has ordered eighty-one new satellites \u2013 including ground spares \u2013 for a complete overhaul of their constellation. Thales Alenia Space is the prime contractor for the spacecraft, while US-based Orbital ATK is responsible for integration with a production line set up in Gilbert, Arizona.<\/p>\n The 10 Iridium NEXT satellites that will launch on the fifth Iridium NEXT mission. Credit: Iridium Communications<\/p>\n The satellites are built around Thales\u2019 Extended Lifetime Bus \u2013 ELiTeBus-1000 \u2013 platform. Each one has a mass of 860 kilograms (1,900 lb) and is expected to operate for at least 20 years. The satellites carry L-band transponders for mobile communications and Ka-band transponders to provide crosslinks between satellites and downlink to ground stations.<\/p>\n The Iridium constellation\u2019s crosslink capability allows each satellite to relay data directly to the four other satellites: those immediately ahead of and behind it in the same orbital plane, and those operating parallel to it in the two adjacent planes.<\/p>\n This allows calls to be routed around the network without needing to pass through ground stations, reducing latency and also cost \u2013 as fewer ground stations are required. The sixty-six operational Iridium satellites are arranged in six planes of eleven spacecraft, orbiting at an altitude of about 780 kilometers (485 miles, 421 nautical miles) and a near-polar inclination of 86.4 degrees.<\/p>\n Iridium NEXT constellation \u2013 via Thales materials<\/p>\n SpaceX was initially contracted to launch seventy Iridium-NEXT satellites, via seven Falcon 9 rockets. Russia\u2019s ISC Kosmotras was also awarded several launches which were to have flown two satellites at a time aboard the Dnepr rocket.<\/p>\n Due to the political situation between Russia and Ukraine \u2013 home to the manufacturer of the R-36 missile upon which the Dnepr was based \u2013 Dnepr launches were put on hold and now appear to have stopped permanently. Iridium was forced to cancel their contract with Kosmotras and have manifested a further five satellites to fly on another Falcon 9 launch as a rideshare with GRACE Follow-On \u2013 a pair of geophysical research satellites that are being launched for NASA and the German Research Centre for Geosciences (GFZ).<\/p>\n When it deploys Iridium satellites, Falcon 9 flies from SpaceX\u2019s West Coast launch site at Vandenberg Air Force Base in California.<\/p>\n Falcon 9 on the SLC-4E pad ahead of Iridium NEXT-5 launch \u2013 Photo by Philip Sloss for NSF\/L2<\/p>\n Space Launch Complex 4E (SLC-4E) was originally built as part of the US Navy\u2019s Point Arguello launch site in the 1960s, becoming part of the US Air Force\u2019s Vandenberg AFB when the two adjacent facilities merged in 1964.<\/p>\n The first launch from the pad \u2013 then designated Point Arguello Launch Complex 2-4 (PALC-2-4) \u2013 came a few weeks after the merger: an Atlas SLV-3 Agena-D deploying a KH-7 reconnaissance satellite. Atlas-Agena rockets continued to use the pad until 1967.<\/p>\n From 1971 to 2005, SLC-4E was used by heavy-lift versions of the Titan III and later Titan IV rockets, beginning with the Titan III(23)D.<\/p>\n The final launch of any Titan rocket was made by a Titan IV(404)B which lifted off from SLC-4E in October 2005, deploying a KH-11 imaging satellite for the National Reconnaissance Office. SpaceX has used the pad since 2013, with Friday\u2019s launch the ninth Falcon mission to fly from Vandenberg.<\/p>\n SpaceX facility at Vandenberg \u2013 Photo by Philip Sloss for NSF\/L2<\/p>\n SpaceX made the first four launches of their contract with Iridium last year \u2013 with successful missions in January, June, October and December placing forty satellites into orbit. The Falcon 9 is designed to be partially reusable, and December\u2019s mission \u2013 designated Iridium-4 by SpaceX \u2013 used the same first stage that had been used for the Iridium-2 launch in June. Friday\u2019s launch also featured a \u201cflight-proven\u201d, or previously-flown first stage \u2013 which was used in last October\u2019s Iridium-3 mission.<\/p>\n The first stage, B1041, made a successful landing aboard SpaceX\u2019s West Coast Autonomous Spaceport Drone Ship (ASDS), Just Read the Instructions, following its previous launch. The stage was returned to shore and refurbished to fly again on Friday\u2019s mission. It was built to Block 4 specifications and as SpaceX does not intend to fly any version other than Block 5 more than twice, B1041 was not recovered again following its second flight. After completing its role in the Iridium-5 mission, the core still made boostback, entry and\/or landing burns, but only to gather data for future recoveries.<\/p>\n One part of the Falcon 9 that SpaceX is attempting to recover is its payload fairing \u2013 the structure that protects the rocket\u2019s payload from the atmosphere during the early stages of flight.<\/p>\n SpaceX has been experimenting with fairing recovery over the last year, equipping one half of the fairing thrusters to provide attitude control and a parachute to slow and guide its descent.<\/p>\n To protect the fairing from being damaged or contaminated by the salt water of the ocean, a recovery boat will position itself underneath the fairing as it descends, catching it in a large net suspended between four pillars rising up from the deck. SpaceX\u2019s West Coast fairing recovery ship is named Mr. Steven.<\/p>\n SpaceX Fairing Recovery boat \u2013 Mr. Steven \u2013 photo from Elon Musk\/SpaceX<\/p>\n During Falcon 9\u2019s previous West Coast launch, which carried Spain\u2019s Paz satellite to orbit late last month, Falcon 9 flew with a new payload fairing and the first attempt was made to recover the fairing via the boat. The attempt came close to success, with the fairing half landing intact in the water a few hundred meters away from Mr. Steven. The fairing was hoisted out of the ocean and brought back to California.<\/p>\n Mr. Steven put to sea on Thursday to support the Iridium-5 launch. At liftoff she will be located downrange ready to make another attempt to catch Falcon\u2019s fairing as it descends. The test wasn\u2019t successful.<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/03\/iridium.jpg\")
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