ULA scrubs the launch of Atlas 5 as SpaceX prepares to repair the rocket for its GPS mission. – Spaceflight Now

The United Launch Alliance Atlas 5 rocket stands above Pad 41 at Cape Canaveral Air Force Base on Tuesday, November 3. Source: United Launch Alliance

The United Lunch Alliance announced plans to launch an Atlas 5 rocket on Wednesday at Cape Canaveral to address the launch pad valve problem, and the SpaceX team, about a mile and a half south, prepared the Falcon 9 rocket for takeoff. A GPS navigation satellite for the US military on Thursday evening.

ULA’s launch team scrubbed the Atlas 5 launch attempt just before 6 PM EST (2300 GMT EST) on Wednesday after an unsuccessful attempt to fix the valve problem. First remotely, then a team of technicians was dispatched to the Atlas 5’s beach launcher.

The Atlas 5 rocket carries payloads classified into orbit by the National Reconnaissance Office, the US government’s spy satellite organization. The launch is designated NROL-101, and the NRO has not disclosed details of the payload’s mission other than to assist in its mission to collect and disseminate information for government intelligence agencies.

ULA will start counting down the Atlas 5 late Wednesday, power the rockets, and conduct guidance system testing and other checks before installing cryogenic propellants on launchers ahead of their scheduled takeoff at 5:54 PM EST (2254 GMT). Proceeded.

However, the launch team stopped the countdown clock after “unexpected system response from a ground system liquid oxygen valve received remote command,” ULA said in a statement.

ULA said, “The team will continue to analyze the system and secure the next launch attempt prior to November 6th.

The next chance to launch the Atlas 5 rocket is Friday, ULA said. The exact time of Friday’s launch attempt wasn’t announced immediately, but the launch time of the mission was about 4 minutes faster per day. Then the Friday launch time is 5:46 PM EST (2246 GMT).

The launch of the Atlas 5 was previously scheduled for Tuesday, but ULA returned the rocket to a vertical hangar near the launch pad, resulting in a 206-foot-tall (63-meter) vehicle.

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Ground crew returned the Atlas 5 to the launch pad late Tuesday to prepare for a launch attempt on Wednesday.

Before the next Atlas 5 launch opportunity, SpaceX plans to launch the Falcon 9 rocket from Pad 40, which opens for 15 minutes on Thursday at 6:24 PM GMT 2324 GMT.

The 70-meter-high Falcon 9 rocket stood on Pad 40 on Wednesday to prepare for launch Thursday evening. The Pad 40 is located about 2.5 km south of the Atlas 5 launch pad in Cape Canaveral.

The SpaceX Falcon 9 rocket stands on pad 40 at Cape Canaveral Air Force Base on November 4. Source: Stephen Clark/Spaceflight Now

The Falcon 9 rocket is ready to loft the GPS 3 SV04 navigation satellite for the U.S. space force, replenishing the location and timing stations used by billions of military and civilian users around the world.

SpaceX attempted to launch a GPS satellite on October 2nd, but an automatic shutdown occurred two seconds before takeoff due to engine problems.

Engineers investigating the October 2 disruption found that two of the nine first-stage engines on the rocket tended to ignite faster than expected. Inspections showed that the pressure rises faster than designed at start-up due to the shut-off relief valves in the gas generators of both engines, and the engine’s sensors detected the problem and stopped counting down.

SpaceX Engineer Checking the masking process It was accidentally left on two Merlin engines as the cause of the countdown, which stopped last month.

Hans Koenigsmann, Vice President of Build and Flight Stability at SpaceX, said, “Looking at the data, both engines tried to start early and an automatic shutdown prevented it.” By doing this, I was able to avoid hard starts that could damage the engine hardware.”

The Merlin engine is powered on with the help of an igniter fluid known as TEA-TEB (or triethyl aluminum-triethylborane), which flashes bright green at the start of the ignition sequence.

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“And we have liquid oxygen, we called kerosene or RP-1,” Koenigsmann said in a conference call with a reporter last week. “And you have to introduce these liquids in the right order. If we do this in the wrong order and we’re injecting liquid oxygen and RP-1 and igniter fluid, we call it a difficult start.”

A hard start will “rabble” the engine in most cases, but it can do damage, Koenigsmann said. “Generally you don’t want it. I want a good start-up.”

SpaceX shipped the Merlin engine back to a test site in central Texas, and inspections found material blocking the line from the gas generators of both engines to the pressure relief valve.

Koenigsmann said the vents, which were only 1/16 inches wide, were blocked by a hardened masking lacquer. He said that a third-party supplier that anodizes aluminum engine parts for SpaceX uses a liquid lacquer similar to a red nail polish.

Lacquers protect certain parts during the anodizing process, but vendors not verified by officials must remove the material before shipping parts to SpaceX for engine manufacturing.

The gas generator in each Merlin engine drives a turbopump that supplies kerosene and liquid oxygen propellant to the main combustion chamber.

Engineers at SpaceX’s McGregor test site showed that the engine worked normally after removing the blockage from the exhaust valve. Koenigsmann said the problem is “very subtle, but it can definitely have a negative impact on engine operation.”

“The GPS 3-4 mission will still use the same boosters as the first launch attempt,” said Walt Lauderdale, director of the GPS 3-4 mission at Space Force’s Space and Missile Systems Center. “The two engines that caused the launch disruption were replaced by engines that were verified through inspection and family tree review, and it was confirmed that there were no masking lacquers left.”

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SpaceX and Space Force officials confirmed that all nine Merlin engines on Saturday’s Falcon 9 rocket were test-launched from pad 40 on Saturday and were ready to fly.

In addition to rockets for GPS missions, engine problems also affected two vehicles for future NASA launches. So far, the issue has only affected missions that will use the new Falcon 9 booster.

The first operational flight of SpaceX’s Crew Dragon spacecraft will take off on November 14 at the Kennedy Space Center by three NASA astronauts and Japanese mission experts to begin a half-year exploration from the International Space Station.

SpaceX is replacing the two Merlin engines on the Falcon 9 rocket for the Crew Dragon mission. Engineers suffered from the same early-start tendencies that the rocket’s engine showed for GPS missions. This issue delayed the release of Crew Dragon from October 31st to November 14th.

Steve Stitch, NASA’s commercial crew program manager, said last week that the agency’s engineers wanted to analyze engine data from a GPS launch before removing the crew dragon for takeoff later this month.

An engine problem delayed the launch of the US-Europe Sentinel-6 Michael Freilich oceanography satellite at Vandenberg Air Force Base in California. The mission was originally scheduled to launch on November 10th, but is currently expected to launch on November 21st.

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