SpaceX successfully carried out a Static Fire test on the Falcon 9 rocket for the first operating Crew Dragon flight, Crew-1. The flight would be SpaceX's second crewed flight and their first rotation mission with four astronauts on board.
The test shooting took place at around 7:49pm EDT at KSC 39A in Florida, according to Space.com. The organization has said that teams would continue to track liftoff environmental conditions and near lead up to launch along the flight route.
The static fire is one of the last crucial checks ahead of the launch, consisting of a near-complete flight countdown rehearsal (the crew would not be on board for the test) to ensure that all spacecraft systems are operating correctly.
Each stage was already checked before shipping to the Kennedy Space Center earlier this year at SpaceX's McGregor, Texas plant, where they underwent final arrangements and integration with each other and Crew Dragon before the entire stack was mounted on the Transporter-Erector (TE).
The Falcon 9 stack rolled out of the Horizontal Integration Facility (HIF) on the Cape Canaveral Air Force Station launch pad on Monday night, after which it was vertically lifted on Tuesday morning.
Later that day, on the second level, teams found a somewhat anomalous reading on a purge valve, leading to a option to replace the valve even if the problem may have been agreed as-is.
From Tuesday evening to Wednesday afternoon, the change-out involved taking the Falcon 9 back down horizontally and halting the static fire inspection.
The team at SpaceX’s rocket development facility in McGregor, Texas completed a static fire test today of the Falcon 9 first stage that will launch Crew Dragon’s first operational mission (Crew-1) with 3 @NASA astronauts and 1 @jaxa_en astronaut on board later this year pic.twitter.com/iagTmZUXDu — SpaceX (@SpaceX) April 24, 2020
Mission control, operating in the Mission Control Center next to the VAB at the Kennedy Space Center from Firing Room 4, went through the entire launch countdown for the drill, including propellant filling of all phases.
RP-1, a specially-refined type of kerosene, started to flow through the first and second phases at T-35 minutes. At the same time, liquid oxygen loading on the first stage began. At T-16 minutes, the second stage began obtaining liquid oxygen.
To minimize the amount of heating and boiloff that happens, the propellants are loaded as late as necessary. The cooler and denser they are, the better Falcon 9 efficiency they will produce.
A brief firing of the nine Merlin 1D first stage engines resulted in the evaluation. In general, this burn is either 3.5 or 7 seconds long. Provided that the Crew Dragon Demo-2 rocket fired a 7-second blast, it is possible that Crew-1 would do the same.
The propellants are depleted after the quick burn and the spacecraft is put in a stable configuration for staff to return to ready Dragon for the dry dress rehearsal with the crew on Thursday's launch day.
Why Is This Move Necessary?
Nevertheless, rather than being for a crewed mission, this particular static fire test has a little more value than normal.
The flight computers found problems with two Merlin 1D gas generators during engine ignition on the first GPS III SV04 launch attempt. Both engines encountered an early pressure buildup and the launch aborted safely at T-2 seconds.
Smaller engines that control the propellant pumps on the main engines are basically gas generators. To power its pumps, every Merlin 1D engine has one gas generator.
A detailed inquiry into the anomaly identified a small flaw with the gas generator.
The engines experiencing problems on the GPS III SV04 mission were extracted from the first stage and sent to SpaceX's test facility in McGregor, Texas. They were placed on a test stand there, where the issue happened again. A gas generator CT scan revealed a clogged vent, only 1.5 mm length.
A red lacquer was found covering the opening when the engine was disassembled. This was a residual masking material from the manufacturing process, as part of the anodized gas generator was used. Hans Koenigsmann, Vice President of Project Assurance, SpaceX, identified the lacquer as being close to nail polish.
Rather than simply being a one-off problem, it was decided to be a potential problem for a whole batch of generators.
All Merlin 1D engines on newly-built boosters, including the first Crew-1 stage, were inspected. Two engines were located on this core with a similar problem. Those engines have been removed or restored since then.
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