Monday, June 26, 2017

Two Launches, Two Landings, Two Days: Falcon 9 Sends Iridium-2 Satellites into Space

Archive photo of the Iridium-1 launch in January 2017. The Iridium-2 launch took place at 1:25 p.m. PDT (4:25 EDT / 20:25 GMT) on June 25, 2017. Photo Credit: SpaceX

SpaceX launched, and landed, its second Falcon 9 in as many days when it sent 10 Iridium NEXT satellites into space. The mission, designated Iridium-2, launched at 1:25 p.m. PDT (4:25 p.m. EDT / 20:25 GMT) on June 25, 2017, from Space Launch Complex 4E (east). Showing it can keep up a rapid launch cadence, just 49 hours before, SpaceX had sent a “flight-proven” booster into space from Kennedy Space Center’s Launch Complex 39A in Florida.

For the flight in California, it was only the fourth launch from SLC-4E – the second in 2017. The first stage of the rocket, core 1036, was a fresh core and featured upgraded titanium grid fins. Previous boosters have used an aluminum design that frequently caught fire during the stage’s re-entry into Earth’s atmosphere.

The 30th Space Wing had predicted a 100 percent chance of acceptable conditions and while mother nature came through, the Falcon 9 was masked in foggy conditions just before launch.

At liftoff, however, the rocket and its nine Merlin-1D engines quickly punched through the clouds into sunny, blue skies to begin its climb to low-Earth orbit.

Just over a minute into flight, the 229-foot (70-meter) tall vehicle experienced the moment of peak mechanical stress on its structure, an area referred to as max-Q. About a minute later, at 2 minutes, 24 seconds after leaving California, the first stage finished its job in sending the Iridium-2 satellites into orbit and separated.

Several seconds later, the second stage’s lone Merlin-1D vacuum engine ignited to power toward a parking orbit, which it reached some 9 minutes after launch.

While the second stage was making its climb skyward, the first stage began its arc toward the Automated Spaceport Drone Ship Just Read The Instructions downrange in the Pacific Ocean.

This launch tied the record for the heaviest Falcon 9 payload with the 10 1,896-pound (860-kilogram) Iridium NEXT satellites and the spacecraft dispenser. To make matters more challenging, before the launch, SpaceX officials warned the parameters for first stage recovery downrange in the Pacific Ocean were “marginal” with cloudy, light rain, and windy conditions.

“Droneship repositioned due to extreme weather,” SpaceX CEO Elon Musk tweeted. “Will be tight.”

Almost six minutes into the flight, the first stage performed a three-engine entry burn to ease itself into the atmosphere. Views of the first stage from SpaceX’s webcast showed the titanium grid fins did not catch fire.



Over the course of the next two minutes, core 1036 with its new grid fins took aim at the drone ship. It punched through low clouds just in time to see the “X” that marked the center of the landing target.

Despite warnings, the first stage would not be successfully recovered, the Hawthorne, California-based company made it look easy with a soft touchdown near the center of Just Read The Instructions some 7 minutes, 45 seconds after leaving the launch pad.

To date, SpaceX has successfully landed 11 Falcon 9 first stage cores 13 times. Two of the 13 landings were from a previously-flown stage. Five were on land, and eight on drone ships.

Since the first successful landing in December 2015, the company has failed to land a Falcon 9 first stage only three times.

There are now several recovered Falcon 9 first stage cores being processed for re-flight. Two of them will be used on the first flight of the Falcon Heavy later this year.

The company is quickly proving the reliability of pre-flown boosters. SES, which saw its SES-10 satellite launched on the first “flight-proven” booster in April 2017, has already said it plans to fly on more recovered stages.

Even Iridium Communications has expressed interest in using a pre-flown booster for one or more of its six remaining flights atop Falcon 9 rockets if it were to speed up the company’s wait time for launches.

“While we are currently flying first-flown launches, I’m open to previously-flown launches, particularly for the second half of our launch schedule,” Space News reported Iridium Communications CEO Matt Desch as saying during a conference call.

According to Space News, Desch said there would be three criteria Iridium would use to decide if it were to use a “flight-proven” rocket: schedule, cost, and reliability. The schedule is the most important factor for Iridium, he said.

Interestingly, the core used for the Iridium-1 mission in January 2017 was flown on the BulgariaSat-1 mission two days before the Iridium-2 flight.

Just under an hour after liftoff, the second stage performed a quick three-second burn. About five minutes later, the first of the 10 Iridium NEXT satellites for the Iridium-2 mission began deploying. One hour, 12 minutes into the mission, all 10 had deployed.

“Ten for 10, it’s a clean sweep,” said Falcon 9 product manager John Insprucker, who was hosting SpaceX’s live webcast. “We can tie a broom to the Falcon 9.”

Iridium Communications is in the midst of replacing its 66-satellite Iridium constellation. Many of the company’s first-generation satellites have been in orbit since 1997.

In total, SpaceX’s Falcon 9 will be launching 75 of 81 second-generation Iridium NEXT satellites over eight missions.

It was hoped by Iridium that the whole Iridium NEXT constellation would be in orbit by the end of 2017. However, for a variety of reasons, including, manufacturing setbacks and launch delays stemming from SpaceX’s two Falcon 9 failures, the completion date has moved into 2018.

These new Iridium NEXT satellites, over the coming year, will replace the world’s largest commercial satellite constellation. The company has described it as one of the largest “tech upgrades” in history.

The spacecraft were built by Thales Alenia Space with the help of Orbital ATK.

The new satellites will replace the legacy satellites one-by-one. A replacement process on a constellation of this size and scale has never been completed before.

The 10 that launched in January have already been integrated into the current constellation. They are designed to provide better and faster call quality and data transfer speeds to Iridium’s customer base.

As each of the legacy satellites are replaced, they will be placed into high or lower orbits in preparation for eventual de-orbiting.

The Iridium-2 mission marked the ninth Falcon 9 flight of 2017 – a new record for the NewSpace company. SpaceX still has about 11 launches manifested for 2017, including the maiden flight of the long-anticipated Falcon Heavy.

SpaceX’s next launch will be from Florida in early July with a static fire test of the Falcon 9 potentially occurring as early as June 29. That mission will see an expendable Falcon 9 send Intelsat-35e into geostationary transfer orbit.

Written by: Derek Richardson
Original source: spaceflightinsider.com

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