Monday, October 9, 2017

SpaceX Launches 10 Iridium NEXT Satellites on Iridium-3 Mission

Launching before dawn, a Falcon 9 sends 10 Iridium NEXT satellites into space for the Iridium-3 mission. Photo Credit: Vandenberg Air Force Base

SpaceX flew the first Falcon 9 rocket in what could be a launch doubleheader for the NewSpace company. The Iridium-3 mission lifted off from Vandenberg Air Force Base and saw the third set of 10 Iridium NEXT satellites placed into space.

Liftoff took place at 5:37 a.m. PDT (8:37 EDT / 12:37 GMT) Oct. 9, 2017, from Space Launch Complex 4E. Supporting the launch was the 30th Space Wing based at Vandenberg Air Force Base.

“This is the fourth Falcon 9 and the third Iridium NEXT launch in 2017 from Vandenberg,” said Col. Michael Hough, 30th Space Wing commander and the launch commander for this mission. “This launch continues to highlight the extraordinary level of teamwork and precision that exists between Team Vandenberg and SpaceX. ”

As said, the Iridium-3 mission was the third such flight by SpaceX on behalf of Iridium Communications in 2017. The previous two occurred in January and June. There are five more launches planned by the middle of 2018 to orbit a total of 75 next-generation Iridium satellites to completely overhaul the company’s voice and data constellation.

Iridium NEXT satellites are built by Thales Alenia Space. Each are about 1,900 pounds (860 kilometers). They have two solar arrays that produce two kilowatts of power and support L- and Ka-band antennas. Each are expected to have an on-orbit lifetime of 15 years at an operational orbit of about 480 miles (780 kilometers) in one of six orbital planes spaced 30 degrees apart.

With 30 now in orbit, the company is well underway with the process of switching out legacy satellites – some of which have been in space since the late 1990s – with the new vehicles. Once all 66 primary satellites, as well as the on-orbit spares, are switched out, the old satellites will be placed in higher or lower orbits in preparation for eventual de-orbiting.

A few seconds before the countdown reached zero, the nine first stage Merlin 1D engines ignited and began to spool up to full power. Three seconds later, the launch restraints released the Falcon 9 rocket and it began to soar skyward. After several seconds of climbing straight up, the booster began to pitch toward the south toward its designated orbit – Plane 4 of the Iridium satellite constellation.

After about 1 minute, 10 seconds of flying, the vehicle experienced maximum dynamic pressure, the point where the stresses on the rocket by the atmosphere are at their highest.

Two minutes, 23 seconds after leaving California, the first stage finished its job and separated several seconds later. The second stage and its lone Merlin vacuum engine then took over to finish the job of delivering the Iridium-3 payload into space. Soon after, no longer needed, the payload fairing protecting the Iridium satellites separated. This occurred at about 3 minutes, 9 seconds into the flight.

The second stage continued to propel the Iridium-3 mission toward orbit for another six minutes before cutting off just after 9 minutes into the flight.

During the flight of the second stage, the first stage performed a series of burns to land on an ocean-going platform in the Pacific Ocean. That first burn – the boostback – occurred several seconds after stage separation and lasted about 30 seconds. At 5 minutes, 41 mission into the mission, the stage performed an entry burn to cushion itself back into Earth’s atmosphere.

About a minute later, the first stage performed its landing burn to softly touch down on the Autonomous Spaceport Drone Ship named Just Read The Instructions some 7 minutes, 23 seconds after leaving California. The drone ship was located about 186 miles (300 kilometers) downrange in the Pacific Ocean.

In space, the second stage continued to coast until a mission elapsed time of about 52 minutes. The vehicle’s engine then ignited for about three seconds to circularize its polar orbit at about 388 miles (625 kilometers). The first set of 10 Iridium satellites began deploying just five minutes later. Each deployment was 90 seconds apart, finishing at a mission elapsed time of 1 hour, 12 minutes.

The Oct. 9 launch was the 42nd Falcon 9 flight since the rocket design began flying in 2010 – the 14th in 2017. It was also the 6th SpaceX mission from Vandenberg Air Force Base, four of which occurring in 2017.

Should the next Falcon 9 launch on schedule, it will fly less than 60 hours later at 6:53 p.m. (22:53 GMT) Oct. 11, 2017, from Kennedy Space Center in Florida. That launch will see the SES-11 satellite orbited for Luxembourg-based SES. Additionally, it will utilized a “flight-proven” booster that first launched during the CRS-10 mission in February 2017. This will also be the first repeat customer to fly on a reused booster.

Written by: Derek Richardson
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