SpaceX have fired up their Falcon 9 v1.1 launch vehicle during a Static Fire (Hot Fire) test on Saturday, allowing for a health check and countdown dress rehearsal ahead of their next flight of their Dragon spacecraft to the International Space Station (ISS). The CRS-3/SpX-3 Dragon is tracking a launch – her first on the upgraded Falcon 9 – on March 16 from Cape Canaveral Air Force Station (CCAFS).

CRS-3:

The latest Falcon 9 launch will be the fourth in her upgraded configuration, following three successful satellite launches – one from Vandenberg and two from SLC-40 at the Cape.

However, unlike her predecessors, this Falcon 9 is sporting four landing legs on her aft, allowing for the latest test objective towards SpaceX’s ultimate goal of a fully reusable rocket system.

Although a number of tests have already been conducted – mainly involving a restart of the First Stage post-staging, allowing it to practise a controlled re-entry – this will be the first mission where a soft splashdown on deployed legs will be attempted, as recently explained by SpaceX to NASASpaceFlight.com.

Following staging, the First Stage will bid farewell to the Second Stage and Dragon, prior to rotating its aft and engines into the direction of travel. Once in the correct orientation, three of Falcon 9’s Merlin 1D engines will conduct a supersonic retro propulsion burn.

Once the First Stage has shut down the three engines, a stable re-entry should then occur. As the Stage begins to drop back to Earth, the center engine will ignite to stabilize the Stage and reduce its velocity.

About 10 seconds into the landing burn, SpaceX will attempt the unique demonstration of deploying the four legs, as the Stage closes in on the water.

Recovery of the first stage from the water will be attempted, although SpaceX noted there is a low probability this will be successfully achieved during this test.

The primary goal of the launch relates lofting the Dragon spacecraft en route to the ISS for her fourth mission to the Station. The spacecraft will be riding uphill on the beefed up rocket for the first time.

The SpX-3 flight will carry a full launch and return complement of 1,580kg/3,476lb of payload, an increase from the previous limit of 800kg, afforded by the increased upmass capabilities of the Falcon 9 v1.1.

For launch, Dragon will carry a record of one GLACIER and two MERLIN freezers for transporting ISS experiment samples.

The external payload in Dragon’s trunk includes the Optical Payload for Lasercomm Science (OPALS) – which will demonstrate high-bandwidth space to ground laser communications, and the High Definition Earth Viewing (HDEV) package consisting of four commercial HD video cameras.

The CRS-3 mission will also involve the delivery of a replacement Extravehicular Mobility Unit (EMU), allowing for the return of a faulty suit on the same vehicle when it returns to Earth. This spacesuit relay is enabled by a specially built rack inside the Dragon.

Static Fire:

Per the primary goals of a Hot Fire test, the effort relates to ensuring that the pad’s fueling systems – and the launch vehicle – function properly in a fully operational environment, with numerous requirements to be successfully proven via such a test, such as the engine ignition and shut down commands, which have to operate as designed, and that the Merlin 1D engines perform properly during start-up.

Tasks also include a full propellant loading sequence, launch countdown operations, engine ignition operations and testing of the pad’s high volume water deluge system.

The first opportunity for the Static Fire was scheduled for Friday. However, unacceptable weather in the region delayed the rollout, pushing the test to Saturday. The window for the test was 1pm local through to 5pm local, although it is understood engineers were working issues on the vehicle for at least the first few hours of the window.

With the test providing a dress rehearsal for the actual launch, controllers would have begun the test with polling to allow for the loading of Falcon 9’s RP-1 propellant with liquid oxygen oxidizer two hours and thirty five minutes before T-0.

This would have likely been followed with fuel and Thrust Vector Control (TVC) bleeding on the second stage, performed at T-1 hour.

At T-13 minutes, a final flight readiness poll would have been conducted, which would then be followed by the final hold point at T-11 minutes.

Per the countdown procedures, the tasks would have entered the terminal count ten minutes before ignition, followed by the launch vehicle being transferred to internal power at four minutes and forty six seconds before T-0.

The Flight Termination System (FTS), used to destroy the rocket in the event of a problem during an actual launch, would have been armed three minutes and eleven seconds before launch, and seven seconds later oxidizer topping ended.

Pressurization of the propellant tanks would have followed, and while a Wet Dress Rehearsal (WDR) – which are no longer required for the Falcon 9 – would have concluded the test at around T-5 seconds, the Static Fire test continued the count through to ignition.

A short burst of the Merlin ID engines on the core stage of the F9 would have then followed, allowing for validation data to be gained on the health of the vehicle and pad systems.

SpaceX PAO confirmed to NASASpaceFlight.com that the Static Fire was classed as successful.

Detanking operations would then have followed, ahead of its lowering on to the Transporter Erector and rollback to the hanger to begin final processing ahead of launch, which normally results in the mating of the payload – in this case the Dragon spacecraft – to the top of the vehicle. However, for this mission, the Static Fire was conducted with the Dragon already integrated on the vehicle.

The Flight Readiness Reviews (FRRs) for the launch vehicle and the spacecraft were concluded last week. A Launch Readiness Review (LRR) – which will include the full results of the Static Fire – will follow in the coming days.

SpaceX remain on track for the March 16 launch of the Falcon 9 and Dragon duo, with the launch window set to open at 4:41am Local.

(Images: SpaceX, Spaceport America and L2)

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