Wednesday, August 8, 2018

First Reflown Block 5 Falcon 9 Sends ‘Merah Putih’ into Orbit

SpaceX’s Falcon 9 rocket rises into the night sky to send the Merah Putih communications satellite into orbit. Photo Credit: Scott Schilke / SpaceFlight Insider

With five months still left in 2018, SpaceX is continuing its rapid-fire launch rate and is nearing an average of two launches per month. The flight of the Merah Putih satellite, using a previously-flown Block 5 Falcon 9, means the company is one step closer to redefining the notion of how frequently flights to space can be carried out.

The Aug. 7, 2018, launch of the Merah Putih (also known as Telkom 4) communications satellite not only saw the spacecraft ferried to a geostationary transfer orbit, it also saw SpaceX successfully carry out its 15th launch of the year (in just eight months’ time). There are as many as nine more flights currently on SpaceX’s launch manifest. If all are completed successfully, it would mean the company has demonstrated the ability to launch, on average, twice per month for a whole calendar year.

One of the most visible pre-launch activities, the static fire test of the Falcon 9 rocket, was conducted less than a week ago at 12:45 p.m. EDT (16:45 GMT) Aug. 2 at 12:45 p.m. EDT (16:45 GMT). 

This procedure, which involved moving the Falcon 9 the the pad, fully fueling the rocket and firing its nine first stage Merlin 1D engines for several seconds, verified all was well with the rocket.

With that complete, SpaceX rolled the vehicle back to its hangar and began the process of attaching the encapsulated Merah Putih payload to the rocket.

For the launch, the company had some two hours in which to send the satellite on its way into the black. However, it didn’t need the extra time as good weather allowed for an on-time liftoff at the very opening of the launch window at 1:18 a.m. EDT (5:18 GMT) from Cape Canaveral Air Force Station’s Space Launch Complex 40 (SLC-40) in Florida.

Around 38 minutes before the opening of the window, SpaceX’s launch director gave the go-ahead to start loading the propellant into the Falcon 9. Three minutes later RP-1 (a highly-refined form of kerosene) was loaded into the vehicle. At the same time, liquid oxygen (LOX) began flowing into the rocket’s first stage.

About 19 minutes later, some 16 minutes before the countdown reached zero, LOX began flowing into the Falcon 9’s second stage.

The nine Merlin 1D engines entered into a chill down phase just seven minutes before liftoff. That was when pace of launch events picked up.

A minute before T-0, the command flight computer went through pre-flight checks in order to ensure all was set for liftoff. Also taking place at this time was the pressurization of the propellant tanks to flight pressures. Fifteen seconds later, the launch director gave a final “go” for launch.

A mere three seconds before the launch window opened, the engine controller began the launch sequence. After that, there was little left but the roar of the first stage’s engines and a bright arc across the humid Florida skies.

One minute, 20 seconds after liftoff, the Falcon 9 and its satellite payload had entered the realm of maximum dynamic pressure (Max-Q). It was at this point that the rocket’s speed as well as the atmospheric pressure placed the stack (the combined rocket and payload fairing) under the greatest amount of stress during the flight.

About 2.5 minutes into the flight, main engine cutoff or “MECO” took place. This was followed four seconds later by “staging” when the rocket’s first and second stages separated. Shortly thereafter, the second stage’s lone Merlin vacuum engine came to life. A little more than a minute later the payload fairing separated and fell away after completing its part of the flight, exposing Merah Putih to the space environment.

Although it had completed its primary objective of sending the communications satellite on its way, the Falcon 9’s first stage still had one more thing to do—return to Earth.

Six minutes, 13 seconds after it had left SLC-40, the stage conducted an entry burn to fine-tune its trajectory and cushion itself back into Earth’s atmosphere. Almost two minutes later, the booster landed on the deck of the Autonomous Spaceport Drone Ship “Of Course I Still Love You” in the Atlantic Ocean some 394 miles (635 kilometers) from Florida.

This stage was previously used to send the Bangabandhu-1 satellite into orbit in May 2018. As such, this was the first re-flight of a Block 5 Falcon 9 variant.

While the first stage was landing, the second stage finished its climb to a low-Earth parking orbit. Engine cutoff occurred at eight minutes, six seconds mission elapsed time. It didn’t reactivate until just over 26 minutes after the mission had begun. This second burn lasted for less than a minute.

The culmination of all these steps saw the Merah Putih satellite placed into a geostationary transfer orbit. Over the coming weeks and months, the spacecraft will use onboard propellant to to circularize into a geostationary orbit.

“Merah Putih” represents the red and white of Indonesia’s flag. The spacecraft incorporates C-band transponders and is based off of the SSL 1300 platform. The satellite is expected to replace the Telkom 1 satellite at 108 degrees east orbital location in geostationary orbit. From this vantage point the satellite should provide services to customers located in Indonesia, South and Southeast Asia.

If everything goes as it is currently envisioned, Merah Putih will remain in service for approximately 15 years and will be operated by PT Telkom Indonesia.

Between the Falcon 9’s first flight in June of 2010 and through 2014, some 14 missions were carried out by the Hawthorne, California-based company. SpaceX has now exceeded this number in the first seven months of 2018 alone.

The launch site for this morning’s mission, SLC-40, is located at the northern end of Cape Canaveral Air Force Station. SLC-40 can trace its legacy back to the early days of the Space Age. It was used by the U.S. Air Force for 55 Titan III and Titan IV launches from 1965 until 2005. Besides 2011 and periods after SpaceX’s CRS-7 and Amos-6 accidents, the site has been kept busy by SpaceX’s launch tempo (since the complex was taken over by the company in May of 2008).

To support Falcon 9 launch operations, the site comes equipped with the concrete pad itself, a flame diverter system. Four lightning towers help prevent an errant strike from damaging or destroying expensive launch vehicles and spacecraft. SLC-40 also has the prerequisite fuel tanks needed to provide the propellants needed to carry out these flights.

If SpaceX’s launch schedule proceeds as planned, the next flight slated for SLC-40 is Telstar 18V. That satellite’s launch is currently expected to take place on Aug. 17, 2018.

Written by: Jason Rhian
Original source: spaceflightinsider.com

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