Scienza & Tecnologia

franky1 ha scritto:
August 29, 2022

Artemis

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The launch director halted today’s Artemis I launch attempt at approximately 8:34 a.m. EDT. The Space Launch System rocket and Orion spacecraft remain in a safe and stable configuration. Launch controllers were continuing to evaluate why a bleed test to get the RS-25 engines on the bottom of the core stage to the proper temperature range for liftoff was not successful, and ran out of time in the two-hour launch window. Engineers are continuing to gather additional data.
 
franky1 ha scritto:
The launch director halted today’s Artemis I launch attempt at approximately 8:34 a.m. EDT. The Space Launch System rocket and Orion spacecraft remain in a safe and stable configuration. Launch controllers were continuing to evaluate why a bleed test to get the RS-25 engines on the bottom of the core stage to the proper temperature range for liftoff was not successful, and ran out of time in the two-hour launch window. Engineers are continuing to gather additional data.
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Engineers are evaluating data gathered during the Artemis I launch attempt Monday, Aug. 29, when teams could not get the rocket’s engines to the proper temperature range required to start the engines at liftoff, and ran out of time in the two-hour launch window to continue. The mission management team will convene Tuesday afternoon to discuss the data and develop a plan forward.


The Space Launch System’s four RS-25 engines must be thermally conditioned before super cold propellant begins flowing through them for liftoff. Launch controllers condition them by increasing the pressure on the core stage liquid hydrogen tank to route, or “bleed” as it is often called, a portion of the approximately minus 423 F liquid hydrogen to the engines. Managers suspect the issue, seen on engine 3, is unlikely to be the result of a problem with the engine itself.


During the countdown, launch controllers worked through several additional issues, including storms in the area that delayed the start of propellant loading operations, a leak at the quick disconnect on the 8-inch line used to fill and drain core stage liquid hydrogen, and a hydrogen leak from a valve used to vent the propellant from the core stage intertank.


NASA will host a media teleconference Tuesday, Aug. 30, at approximately 6 p.m. EDT to provide an update on data analysis and discussions. The time is subject to change. While managers have not yet set a date for the next launch attempt, the earliest possible opportunity is Friday, Sept. 2, during a two-hour launch window that opens at 12:48 p.m.

 

Artemis

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After standing down on today’s Artemis I launch attempt when engineers could not overcome a hydrogen leak in a quick disconnect, an interface between the liquid hydrogen fuel feed line and the Space Launch System (SLS) rocket, mission managers met and decided they will forego additional launch attempts in early September.


Over the next several days, teams will establish access to the area of the leak at Launch Pad 39B, and in parallel conduct a schedule assessment to provide additional data that will inform a decision on whether to perform work to replace a seal either at the pad, where it can be tested under cryogenic conditions, or inside the Vehicle Assembly Building.


To meet the requirement by the Eastern Range for the certification on the flight termination system, currently set at 25 days, NASA will need to roll the rocket and spacecraft back to the VAB before the next launch attempt to reset the system’s batteries. The flight termination system is required on all rockets to protect public safety.


During today’s launch attempt, engineers saw a leak in a cavity between the ground side and rocket side plates surrounding an 8-inch line used to fill and drain liquid hydrogen from the SLS rocket. Three attempts at reseating the seal were unsuccessful. While in an early phase of hydrogen loading operations called chilldown, when launch controllers cool down the lines and propulsion system prior to flowing super cold liquid hydrogen into the rocket’s tank at minus 423 degrees F, an inadvertent command was sent that temporarily raised the pressure in the system. While the rocket remained safe and it is too early to tell whether the bump in pressurization contributed to the cause of the leaky seal, engineers are examining the issue.


Because of the complex orbital mechanics involved in launching to the Moon, NASA would have had to launch Artemis I by Tuesday, Sept. 6 as part of the current launch period. View a list of launch windows here.

 
September 8, 2022

Artemis

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Engineers are making progress repairing the area where a liquid hydrogen leak was detected during the Artemis I launch attempt Sept. 3, and NASA is preserving options for the next launch opportunity as early as Friday, Sept. 23.


Technicians constructed a tent-like enclosure around the work area to protect the hardware and teams from weather and other environmental conditions at Launch Pad 39B. They have disconnected the ground- and rocket-side plates on the interface, called a quick disconnect, for the liquid hydrogen fuel feed line, performed initial inspections, and began replacing two seals – one surrounding the 8-inch line used to fill and drain liquid hydrogen from the core stage, and another surrounding the 4-inch bleed line used to redirect some of the propellant during tanking operations. The SLS rocket and Orion spacecraft are in good condition while remaining at the launch pad.


Once the work is complete, engineers will reconnect the plates and perform initial tests to evaluate the new seals. Teams will check the new seals under cryogenic, or supercold, conditions no earlier than Sept. 17 in which the rocket’s core stage and interim cryogenic propulsion stage will be loaded with liquid oxygen and liquid hydrogen to validate the repair under the conditions it would experience on launch day. Engineers are in the process of developing a full plan for the checkouts.


NASA has submitted a request to the Eastern Range for an extension of the current testing requirement for the flight termination system. NASA is respecting the range’s processes for review of the request, and the agency continues to provide detailed information to support a range decision.


In the meantime, NASA is instructing the Artemis team to move forward with all preparations required for testing, followed by launch, including preparations to ensure adequate supplies of propellants and gases used in tanking operations, as well as flight operations planning for the mission. NASA has requested the following launch opportunities:


  • Sept 23: Two-hour launch window opens at 6:47 a.m. EDT; landing on Oct. 18
  • Sept. 27: 70-minute launch window opens at 11:37 a.m.; landing on Nov. 5

NASA’s teams internally are preparing to support additional dates in the event flexibility is required. The agency will evaluate and adjust launch opportunities and alternate dates based on progress at the pad and to align with other planned activities, including DART’s planned impact with an asteroid, the west coast launch of a government payload, and the launch of Crew-5 to the International Space Station.


Listen to a replay of today’s media teleconference on the status of the Artemis I mission. Artemis I is an uncrewed flight test to provide a foundation for human exploration in deep space and demonstrate our commitment and capability to extend human existence to the Moon and beyond.

 
www.media.inaf.it

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