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Home / Science / ULA removed the Atlas 5 launch missile when SpaceX was ready to repair the missile for the GPS mission – Spaceflight Now

ULA removed the Atlas 5 launch missile when SpaceX was ready to repair the missile for the GPS mission – Spaceflight Now



A United Launch Alliance Atlas 5 missile stands on base 41 at Cape Canaveral Air Force Station on Tuesday, November 3. Source: United Launch Alliance

The United Launch Alliance canceled plans to launch an Atlas 5 missile on Wednesday at Cape Canaveral to address the problem with the valves at the launch pad, while the SpaceX team a mile and a half south had prepared a rocket. Falcon 9 fire to take off Thursday evening with a GPS navigation satellite for the US military.

ULA’s launch team tested the Atlas 5 launch attempt on Wednesday just before 6 p.m. EST (2300 GMT) after unsuccessful attempts to fix the valve problem, first remotely and then with a Technician team sent to Atlas 5’s seaside launch pad.

The Atlas 5 missile will carry a classified payload into orbit for the National Reconnaissance Office, the US government’s spy satellite agency. The launch is named NROL-101, and the NRO has not revealed any specific details about the payload duties, other than that it will help the agency in the mission to collect and disseminate information to agencies. government intelligence.

ULA starts a Atlas 5 countdown late Wednesday morning, launches rockets and conducts guidance system checks and other tests before loading frozen launchers into the launch pad before scheduled takeoff at 5:54 pm EST (2254 GMT).

But the launch team stopped the countdown clock after “the system’s sudden response from the remote controlled ground system’s liquid oxygen valves,” ULA said in a statement.

“The team continues to analyze the system and will defend our next launch no earlier than November 6,” said ULA.

The next chance to launch the Atlas 5 missile will be Friday, ULA said. The exact timing for Friday’s launch attempt was not immediately announced, but the mission’s launch time moved about four minutes earlier each day. That will put a Friday launch time around 5:46 p.m. EST (2246 GMT).

The Atlas 5’s launch was previously scheduled for Tuesday, but ULA sent the missile back to the vertical hangar near the launch pad to replace a duct of the air supply environment control system. Conditioning for top-secret NRO payload on top of a 206-foot (63-meter) vehicle.

Off-ground personnel brought Atlas 5 back to its launch pad late on Tuesday in preparation for Wednesday’s launch attempt.

Ahead of the next Atlas 5 launch opportunity, SpaceX plans to launch the Falcon 9 missile from nearby platform 40 during 15 minutes of window opening at 6:24 pm EST (2324 GMT) on Thursday.

The 229-foot (70-meter) Falcon 9 rocket stood on a 40-foot platform on Wednesday in preparation for launch Thursday night. Pad 40 is located about 2.5 km south of the Atlas 5 launch pad in Cape Canaveral.

A SpaceX Falcon 9 rocket stands on pedestal 40 at Cape Canaveral Air Force Station on Nov. 4 Image Provider: Stephen Clark / Spaceflight Now

The Falcon 9 missile is ready to upgrade the SV04 GPS 3 navigation satellite for the US Space Force, adding to the fleet of navigation and timing stations used by billions of military and civilian users. around the world.

SpaceX attempted to launch a GPS satellite on October 2, but an engine failure forced itself to cancel just two seconds before takeoff.

The engineers investigating the October 2 cancellation found that two of the nine early-stage engines on the rocket tended to ignite earlier than expected in a split second. Tests showed clogged exhaust valves in the two engines’ gas generators caused pressure to rise earlier than designed at start-up, and sensors on the engine detected the malfunction and paused the countdown.

SpaceX engineers identified the mask treatment accidentally left behind in two Merlin engines as the cause of the countdown being canceled last month.

Hans Koenigsmann, vice president for fabrication and reliability at SpaceX, said: “When we looked at the data, we found that two of the engines attempted to start early and the auto-canceling stopped. block that. “And by doing that, it prevented a difficult start-up that could harm the engine hardware.”

Merlin engines work strongly with help from an ignition liquid called TEA-TEB – or triethylaluminium-triethylborane – that emits a bright green light at the top of the ignition sequence.

“And then we have liquid oxygen, and we have kerosene, or RP-1 as the name implies,” Koenigsmann said last week during a meeting with reporters. “And you need to introduce these liquids in the correct order. If you do this in the wrong order, if you happen to throw liquid oxygen and RP-1 and ignition liquid in, then what happens which we call it a tough start.

A difficult start, Koenigsmann says, will cause the engine to “buzz” in most cases, but can cause damage. “So in general, you don’t want that. You want a good start-up.

SpaceX shipped the Merlin engines back to a test site in Central Texas, where tests showed that a substance clogged the way to the pressure reducing valve in the gas generator on two engines.

Koenigsmann says the vent, which is only one-sixteenth an inch wide, has been obscured by the hard lacquer. He says liquid lacquer – similar to red nail polish – is used by a third-party supplier to anode aluminum engine components for SpaceX.

The lacquer layer protects certain parts during anodizing treatment, but the supplier – which officials did not identify – is said to remove the material before shipping the components to SpaceX for production. engine.

The gas generators on each Merlin engine drive a jet turbine unit that feeds kerosene and liquid oxygen propellant into the main combustion chamber.

Engineers at SpaceX’s McGregor test ground have proven that engines operate normally after removing the blockage from the vent valve. The problem, Koenigsmann says, is “very subtle, but clearly there could be some negative effects on engine performance.”

“The GPS 3-4 mission will still use the booster device as the first launch,” said Walt Lauderdale, GPS 3-4 mission director from the Space Force’s Space and Missile Systems Center. “The two engines that led to the discontinuation have been replaced with those that have been verified by pedigree inspection and review so that there are no masking lacquer remaining.”

SpaceX and Space Force officials have verified all nine Merlin engines on the Falcon 9 rocket ready for flight after a test shot on the 40 platform on Saturday.

Besides the rockets for the GPS mission, the engine issue also affects vehicles for some of NASA’s upcoming launches. So far, the issue has only affected missions planned to use the new Falcon 9 boosters.

SpaceX’s Crew Dragon spaceship’s first operational flight will take off on November 14 from the Kennedy Space Center along with three NASA astronauts and a Japanese mission specialist to begin the towing expedition. half a year on the International Space Station.

SpaceX is replacing the two Merlin engines on the Falcon 9 rocket for the Crew Dragon mission, which engineers have seen tend to start off like the engines on the rockets for the GPS mission. The incident delayed the Crew Dragon’s launch from October 31st to November 14.

Steve Stich, NASA’s commercial crew program manager, said last week that the agency’s engineers wanted to analyze engine data from the GPS launch before the Crew Dragon took off later this month. .

Engine malfunctions have also delayed the launch of the US-Europe Sentinel-6 Michael Freilich oceanographic satellite from Vandenberg Air Force Base in California. That mission was originally supposed to be carried out on November 10, but is now scheduled for launch on November 21.

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Follow Stephen Clark on Twitter: @ StephenClark1.




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