Artemis: NASA details its plans for a successful future launch

This Saturday, NASA aborted the second attempt to launch the Artemis 1 mission into lunar orbit after engineers failed to fix a hydrogen leak that occurred while loading fuel into the spacecraft’s tanks of the rocket’s center stage.

After a failed second launch attempt, NASA likely won’t make a third attempt in September. The US space agency explains that the hydrogen leak occurred at “the junction between the liquid hydrogen supply line and the Space Launch System (SLS) rocket.” Drawback: This SLS is the only one that can carry an Orion spacecraft, astronauts, and supplies to the Moon in a single mission.

The second launch of the unmanned Artemis 1 mission was scheduled for Saturday from the Kennedy Space Center in Florida. NASA’s Artemis mission team had already canceled a launch attempt on August 29 when engineers failed to cool the four RS-25 engines to minus 250°C, a necessary step to ensure the main stage was not damaged during the eight-minute low Earth flight. orbit. . After reaching low Earth orbit, the main stage should really separate from the upper stage and the Orion spacecraft.

Device center point

The Boeing SLS central stage is 64.6 meters high with a diameter of 8.4 meters. It stores cryogenic liquid hydrogen and liquid oxygen, as well as power systems for four R2-25 stage engines. During the second launch attempt, one of the four engines was warmer than the others, according to NASA. This test, called the “release test”, is performed before the ultra-cold liquid hydrogen enters the rocket’s main stage.

After the failed attempt to launch the Artemis 1 mission on Saturday, NASA said it had tried to make up for the leak three times. “Engineers have discovered a leak in the cavity between the ground and rocket plates surrounding the 8-inch line used to fill and vent liquid hydrogen from the SLS rocket. Three attempts to reattach the seal were unsuccessful,” NASA said on Saturday evening.

NASA is investigating whether an “unintentional command” sent early in the hydrogen fueling phase may have temporarily increased system pressure and may have contributed to the seal leaking.

Launch delayed

“During the initial phase of hydrogen loading operations, called cooldown, during which launch controllers cool the piping and propulsion system before supplying supercold liquid hydrogen to the rocket launch tank, an involuntary command was sent that temporarily increased the pressure in the system. Although the rocket remained intact and it’s too early to tell if the increased pressure contributed to the cause of the seal leak, engineers are looking into the matter.

About three hours before Saturday’s launch window opened, Artemis launch director Charlie Blackwell-Thompson decided to cancel the second attempt. NASA has reserved backup launches for Monday or Tuesday this week, but concluded it would take longer to fix a new hydrogen leak, Reuters reported. The next available window is between September 19 and 30, or another window in October, NASA Assistant Administrator Jim Free said during a press briefing.

Mike Sarafin, head of the NASA Artemis mission, will need “several weeks of work” to resolve the current technical issues. If this means returning the SLS to the assembly building, then any launch could be pushed back to mid-October.

Draconian terms

According to NASA’s Artemis mission availability web page, there are 11 launch opportunities between October 17 and 31. A rocket cannot be launched on any given day: four basic criteria must be met:

  • Launch day must take into account the Moon’s position in its lunar cycle so that the upper stage of the SLS rocket can program the translunar injection in such a way as to intercept the “launch pad” of the far retrograde lunar orbit.
  • The resulting trajectory should allow Orion not to stay in the dark for more than 90 minutes at a time, so that the solar panel wings can receive and convert sunlight into electricity.
  • The trajectory must account for the “jump” technique planned during Orion’s return to Earth, which involves diving the spacecraft into the upper Earth’s atmosphere, decelerating, and exiting.
  • The launch date should allow for a daylight landing of Orion to facilitate recovery of the spacecraft in the Pacific.

Source: .com

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