Defective sensor may have eliminated NASA’s massive SLS rocket launch

After the launch attempt of a Space Launch System rocket on Monday was called off, NASA officials said they are working toward a second attempt to fly the Artemis I mission on Saturday, September 3.

NASA Flight Controllers Stop the first launch attempt After they were unable to verify that one of the four main engines of the SLS rocket – engine number. 3 – Properly cooled to -420 degrees Fahrenheit before ignition. Engines must be cooled to extremely cold temperatures in order to handle the injection of highly liquid hydrogen and oxygen fuels.

During a briefing Tuesday evening, NASA’s SLS rocket program manager John Honeycutt said his engineering team believed the engine had already cooled from ambient temperature to nearly the required level but had not been properly measured by a faulty temperature sensor. .

“The way the sensor behaves doesn’t match the physics of the situation,” Honeycutt said.

The problem with NASA is that the sensor cannot be replaced easily and is very likely to necessitate a return to the Vehicle Assembly Building at the Kennedy Space Center in Florida, a few kilometers from the launch pad. This will delay the launch of the rocket at least until October, and the space agency has been concerned about wear and tear on a rocket now stacked for nearly a year.

Honeycutt said he was confident liquid hydrogen was flowing into the engine not. 3 during Monday’s countdown and that other sensors, including pressure measurements, indicated that the engine was in an environment that would have cooled properly. So, he said, his team is working on a “flight logic” plan that would allow the missile to launch without getting good data from the engine’s temperature sensor.

“We will look at all the other data we have and [will] Use it to make an informed decision.”

Accordingly, NASA’s current plan includes some work on the launch pad today, including checking an area where a small hydrogen leak occurred during Monday’s countdown. Then, if officials are satisfied with those inspections and the rationale for their flight to deal with the faulty temperature sensor, the agency will begin the countdown on Thursday. On this schedule, refueling operations will begin Saturday morning, just before 2:17 PM EDT (18:17 UTC) to open a two-hour launch window. To give the launch team more time to work on the engine cooling problem, a process known as “conditioning” the engines will begin much earlier in the countdown than on Monday.

It was not immediately clear from Tuesday’s press conference what the implications would be at all with a warmer-than-normal main engine. From a physical point of view, igniting extremely cold fuel in a warmer-than-expected engine would likely do serious damage to the RS-25’s turbopump, at least. Presumably, therefore, NASA would not launch the SLS rocket without high confidence in the logic of its flight.

NASA has until September 5 to launch the booster before it is taken off the platform for renovation. As the September 3 launch date approaches, the space agency will closely monitor the weather forecast as well as manage technical issues. Although thunderstorms occur frequently along the Florida coast during summer afternoons, Launch weather officer Mike Burger said the overland flow should be fairly strong this weekend. This should push the sea breeze further inland and allow for some opportunities to set in within a two-hour window. If the weather refuses to try, NASA is taking action to attempt the Sept. 5 launch.

Officials insisted during Tuesday’s press conference that they are confident of moving forward with the launch attempt. Although the space agency heavily touted Artemis I’s first launch attempt on Monday — the launch of the unmanned Orion spacecraft to the moon drew celebrity appearances, social media promotions, and Vice President Kamala Harris’ visit to the Florida Spaceport —NASA has not yet completed a refueling test.

Despite this, the space agency hopes to be able to fully refuel the rocket on Saturday and count all the way to T-0 without any further problems.