UPDATE MAY 23 @ 8:45am EDT: New photos added and updates on spacecraft operations since launch and deployment in orbit. “We have good telemetry from all 5 Iridium NEXT satellites – and got it on the first pass,” said Iridium CEO Matt Desch on Twitter after launch. “Thank you SpaceX, thank you Thales Alenia. Complete success!”
Telemetry from both GRACE-FO satellites meanwhile indicates that both are healthy. For the next few days they will be in different orbits, one slightly lower than the other. The different orbits cause them to move apart until the lower satellite is 137 miles (220 kilometers) in front of the other, the optimal separation distance for their measurements. At that point, the lower satellite will be moved up into the same orbit as the higher satellite. After these maneuvers, the mission begins an 85-day in-orbit checkout phase. Mission managers will evaluate the instruments and satellite systems and perform calibration and alignment procedures. After that, the satellites will begin gathering and processing science data. The first science data are expected to be delivered to users in about seven months.
ORIGINAL STORY – Five Iridium NEXT global mobile communications satellites and a pair of formation-flying, gravity-measuring spacecraft rose to orbit earlier today (Monday, 22 May) aboard an Upgraded Falcon 9 booster. Liftoff of the 230-foot-tall (70-meter) rocket occurred at 12:47:58 p.m. EDT from Space Launch Complex (SLC)-4E at Vandenberg Air Force Base, Calif., marking SpaceX’s tenth commercial flight out of the mountain-ringed launch site, near Lompoc in Santa Barbara County. The launch came a day after Iridium became only the second organization to be recognized by the International Maritime Organization (IMO) Maritime Safety Committee (MSC) to provide mobile satellite services in the Global Maritime Distress Safety System (GMDSS), ending a decades-long industry monopoly and bringing “competition and truly global coverage to mariners sailing any of the world’s oceans”.
First used by SpaceX back in September 2013, SLC-4E has seen the launches of Canada’s CASSIOPE multi-role science platform, NASA’s Jason-3 ocean altimetry spacecraft, Spain’s Paz radar-imaging spacecraft, five previous batches of the Iridium NEXT constellation and Taiwan’s Formosat-5 Earth observation satellite, with up to six more Vandenberg flights planned for 2018. Today’s mission carried five more Iridium NEXT satellites—bringing to 55 the total number launched by SpaceX since January 2017—into low-Earth orbit, together with the joint U.S.-German Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) payload.
Aboard the Upgraded Falcon 9’s payload fairing were five Iridium NEXT satellites and the Gravity Recovery and Climate Experiment-Follow On (GRACE-FO) twins. Photo Credit: NASAOver the course of the last year, Iridium NEXT has become a regular feature of the SpaceX launch campaign. Contracts between the McLean, Va.-based telecommunications firm and the Hawthorne, Calif.-headquartered launch services provider were inked way back in June 2010 and, at the time, represented the largest single launch deal ever signed, worth an estimated $492 million. Over the coming months, Iridium NEXT will completely replace its aging network of first-generation satellites, whose earliest members were launched two decades ago. Iridium NEXT is overseen by prime contractor Thales Alenia Space, with its subcontractor Orbital ATK selected to build the operational satellites, together with on-orbit and ground-based spares.
Each Iridium NEXT bird is based upon the Extended LifeTime Bus (EliTeBus)-1000, which previously saw service for the low-orbiting GlobalStar communications satellites. Weighing around 1,760 pounds (800 kg), they are powered by twin solar arrays and operate at a mean altitude of 485 miles (780 km), inclined 86.4 degrees to the equator, having the capability of a decade-long lifespan. Their solar arrays, when fully unfurled, span 31 feet (9.4 meters) and generate two kilowatts of electricity, a 50-percent uplift over the power-producing potential of earlier Iridiums.
Under the original contract, SpaceX was expected to deliver 70 Iridium NEXT satellites into orbit, over seven missions, but in January 2017 it was announced that it would benefit from a “rideshare” arrangement, flying an additional five “spares” on an eighth Upgraded Falcon 9. It was noted that this additional mission would be co-manifested with the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) payload. Two more missions, tentatively scheduled for June and August 2018, will deliver another 20 Iridium NEXT birds to orbit, bringing SpaceX’s total tally to 75.
According to Iridium CEO Matt Desch, the NEXT constellation is already supporting the on-orbit testing of the new Iridium Certus broadband service, which provides safety and critical L-band communications connectivity and promises speeds as high as 1.4 Mbps. Iridium expects Certus to be active on all of its NEXT satellites by the late summer of 2018. “Iridium Certus is going to fundamentally change the status quo in satellite connectivity for aviation, maritime, land-mobile, Internet of Things (IoT) and government users,” explained Mr. Desch in an Iridium news release. “Achieving this major milestone continues our momentum for our mission to introduce world-changing broadband services and applications designed to help our partners provide critical connectivity solutions, both standalone and in support of other broadband technologies.”
Yesterday, 21 May, Iridium announced that the International Maritime Organization’s (IMO) Maritime Safety Committee (MSC) had agreed to recognize that the Iridium network had met all the criteria necessary to provide mobile satellite services in the Global Maritime Distress Safety System (GMDSS) and to adopt the “Statement of Recognition” proposed by the United States as a Committee Resolution. In doing so, this ended a decades-long industry monopoly, in which only one company—the London-based International Maritime Satellite Organisation (INMARSAT)—was authorized to provide satellite GMDSS services. Iridium’s authorization is expected to “bring competition and truly global coverage to mariners sailing any of the world’s oceans,” noted Iridium.
“This is a historic moment for the maritime industry and an honor for Iridium to be the second-ever recognized provider for GMDSS services,” said Bryan Hartin, executive vice president, Iridium. “This is the dawn of a new era for mariner safety. We’ll bring a new choice and upgraded capabilities for mariners along with our truly global coverage that will for the first time extend the reach of satellite-based GMDSS to even the most remote waterways.” Iridium formally began the process to become a recognized GMDSS mobile satellite service provider in April 2013 and the organization plans to begin providing GMDSS service in early 2020. “This has been a long time coming, and we are ecstatic to gain this very important recognition from the IMO. We are equally proud to ensure mariners will have access to this critical system from anywhere in the world that they sail,” said Mr. Desch. “Iridium has established itself as a trusted maritime safety provider for over a decade, and this recognition is a testament to both that trust and the capabilities offered by our satellite network.”
Alongside the five Iridium NEXT satellites for today’s mission was GRACE-FO, which—as its name implies—represents a “follow-on” program to the highly successful 2002-2017 Gravity Recovery and Climate Experiment, conducted between NASA and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, or DLR). Launched atop a Rokot booster from Russia’s Plesetsk cosmodrome in March 2002, GRACE consisted of two low-orbiting satellites, which undertook detailed measurements of gravity-field anomalies in support of oceanography, geology and climate research. Flying 137 miles (220 km) apart, the satellites used microwave ranging, Global Positioning System (GPS) timing, star-trackers and an accelerometer to precisely measure the distance between themselves to within a fraction of the diameter of a human hair, in order to better understand our planet’s ever-changing gravitational dynamics.
Throughout their long mission, the GRACE duo returned monthly gravity anomaly maps which were a thousand times more accurate than earlier measurements. This contributed significantly to scientists’ understanding of long-range physical processes on Earth, ranging from ice-sheet thinning and mass-loss in Greenland and Antarctica to magma movement within the planet’s interior. GRACE enabled determinations of planet-wide changes in water distribution, including sea-level rises caused by glacial melting, and has provided new insights into global ocean circulation, weather and climate processes, earthquakes, geodetic modelling and even the impact of human interactions, such as from the depletion of large aquifers. All told, by the end of its life, the mission’s data was utilized in more than 4,300 research publications spanning multiple Earth sciences fields.
“GRACE has provided paradigm-shifting insights into the interactions of our planet’s ocean, atmosphere and solid Earth components,” said Principal Investigator Byron Tapley of the University of Texas at Austin. “It has advanced our understanding of the contribution of polar ice melt to global sea level rise and the amount of atmospheric heat absorbed by the ocean. Recent applications include monitoring and managing global water resources used for consumption, agriculture and industry; and assessing flood and earthquake hazards.”
However, in order to function, both satellites had to be fully functional. Last September, an age-related battery issue cropped up in the GRACE-2 satellite and by mid-October it became clear that the problem could not be rectified. This prompted a decision to wind the mission to a conclusion. GRACE-2 re-entered the atmosphere in December, followed by GRACE-1 in mid-March 2018. Originally baselined to operate for just five years, the twins had returned an unprecedented 15 years of advanced science. “GRACE was an excellent example of a research satellite mission that advanced science and also provided near-term societal benefits,” said Michael Freilich, director of the Earth Science Division at NASA Headquarters in Washington, D.C. “Using cutting-edge technology to make exquisitely precise distance measurements, GRACE improved our scientific understanding of our complex home planet, while at the same time providing information that was used in the U.S. and internationally to improve the accuracy of environmental monitoring and forecasts.”
Yet the demise of GRACE by no means marked the end of their mission. A “follow-on” program, dubbed GRACE-FO, had been in work for several years, with contracts to build another pair of spacecraft having been signed in November 2012 between NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., and Ottobrunn, Germany-headquartered EADS Astrium (now part of Airbus Defence and Space). The GRACE-FO twins would be virtually identical to their predecessors, trapezoidal in cross-section, and each measuring 10 feet (3 meters) x 6.6 feet (2 meters) x 2.6 feet (0.8 meters) and some 1,280 pounds (580 kg) in weight. Also like their predecessors, they would operate in a 310-mile-high (500 km) Sun-synchronous orbit, at a near-polar inclination of 89.9 degrees to the equator, and flying about 137 miles (220 km) apart. Built on the framework of Airbus’ flight-proven Flexbus platform, the spacecraft saw previous service not only for the original GRACE twins, but also for Germany’s 2000-launched Challenging Mini-Satellite Payload (CHAMP), an Earth resources and gravity-mapping mission.
In May 2015, Airbus announced that the structures for the two GRACE-FO satellites had been delivered and the development and design phase of the mission had been completed at its Defence and Space facility in Friedrichshafen, Germany. This allowed the start of building of the mission itself. By late 2016, the first GRACE-FO satellite was completed and despatched to the Industrieanlagen-Betriebsgesellschaft (IABG) analysis and test engineering center in Ottobrunn, near Munich, followed by its twin a few weeks later. At Ottobrunn, they underwent extensive testing—including acoustic runs in IABG’s 50,000-cubic-foot (1,400-cubic-meter) echo chamber in May 2017—and last November Airbus announced that the year-long test campaign had been successfully completed. On 11 December, the twins were loaded aboard an air freighter at Munich airport for delivery to Vandenberg. Counting the satellites and their support and test equipment, a total of more than 100,700 pounds (45,700 kg) of hardware arrived at the West Coast launch site on 12 December in support of the GRACE-FO mission.
As a “rideshare” mission with the five Iridium NEXT birds, the payload configuration for this flight was a notably bespoke one. SpaceX provided a single, five-satellite dispenser for Iridium, sitting at the “bottom” of the payload stack, whilst Airbus provided its own dispenser for the GRACE-FO twins, mounted above it. “This structure was developed in classical configuration,” Airbus explained in an August 2017 news release, “with a central carbon-fiber cylinder, with the satellites held in place by four hold-down and release mechanisms, which each have springs, connectors and necessary harnesses.”
The processing campaign at Vandenberg proceeded with characteristic quietness, as the satellites were installed into their respective dispenser and encapsulated within the payload fairing. A customary Static Fire Test of the nine Merlin 1D+ engines on the Upgraded Falcon 9’s first stage was conducted on Friday, 18 May, allowing SpaceX to declare its readiness to support an opening launch attempt on Monday, 22 May, a 24-hour slip past its original target. “We were ready for 5/21, but the base isn’t,” tweeted Iridium CEO Matt Desch. “Let’s hope for good weather and a great launch on 5/22 instead.” In the aftermath of the test, the booster was returned to a horizontal configuration and taken back to the assembly building, where the bullet-like payload fairing was installed. The stack returned to SLC-4E and was elevated to the vertical yesterday.
Loading of the booster with liquid oxygen and a highly refined form of rocket-grade kerosene, known as “RP-1”, got underway in the final hour before launch. Weather conditions proved 100-percent favorable, with crystal-clear blue skies backdropping SLC-4E and its SpaceX tenant.
Passing T-10 minutes in the countdown, the terminal autosequencer was initiated and the first-stage engines were chilled down, ahead of the ignition sequence. At T-2 minutes, the Air Force Range Safety Officer verified that all ground-side assets were “Go for Launch” and the vehicle transitioned to Internal Power and assumed primary command of all critical functions, entering “Startup” at T-1 minute. At this point, the Niagara deluge system began flooding the surface of SLC-4E with 30,000 gallons (113,500 liters) of water, per minute, to suppress the acoustic energy at liftoff.
At T-3 seconds, the nine Merlins thundered to life, ramping up to a combined thrust of 1.5 million pounds (680,000 kg). Liftoff occurred precisely on time at 12:47 p.m. PDT and the vehicle followed a perfect ascent trajectory, its first stage providing the muscle for the first 2.5 minutes, before separating. As an old-style “Block 4”, this first stage—which previously saw service to loft the top-secret Zuma mission in January—was not intended to be recovered. Although the first stage was not recovered, an attempt was made to retrieve the Upgraded Falcon 9’s payload fairing, using the Mr. Steven vessel off the California coast. A successful water landing of a fairing was achieved earlier in 2018, following February’s Paz launch, with high hopes that today’s mission would actually reach Mr. Steven and his capture net. “Fairing separation confirmed,” SpaceX tweeted at 12:51 p.m. PDT. However, although the two halves of the fairing successfully descended beneath parachutes into the Pacific Ocean, they narrowly missed the capture net.
Meanwhile, the second stage picked up the baton to deliver its payload of seven satellites to their respective orbital positions. It burned for seven minutes and 15 seconds, shutting down a little over ten minutes after leaving Vandenberg. Eighty seconds later, the GRACE-FO twins were deployed and the second stage moved into a “coasting” phase, lasting three-quarters of an hour. A second burn, lasting just a few seconds, then positioned the Iridium NEXT group for deployment, which kicked off about an hour after launch. Departing their dispenser at one every 100 seconds, all five satellites were successfully deployed over a seven-minute period.
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