If at first you don't succeed: Engineers power up the computers of NASA's monster SLS core stage once again

NASA has fired up the avionics of the Artemis I core stage ahead of tomorrow's planned redo of the prematurely terminated hotfire test.

The milestone came a fortnight after engineers completed the assembly of the twin solid rocket boosters atop the mobile launcher currently sat inside Kennedy Space Center's Vehicle Assembly Building. The first of the 10 booster segments was placed back in November last year, and the final nose assembly was dropped into place on 2 March.

Those boosters are, however, missing a key ingredient: the SLS core stage, which continues to languish on the B-2 test stand at NASA's Stennis Space Center near Bay St. Louis, Mississippi.

Once managers give the nod on the test day, the stage's tanks will be filled with 700,000 gallons of propellant. Six barges loaded with liquid oxygen and hydrogen will supply the test stand. Each barge represents between 18 and 20 tanker trucks' worth of propellant.

The previous run suffered a premature cut-off when "intentionally conservative" test parameters resulted in a shutdown of the four ex-Space Shuttle engines at the 67.2 second mark.

While useful data was collected, a lengthier burn was deemed essential in order to validate the system. At least four minutes of firing is required, and the full eight minutes of a simulated launch would be ideal, before the final tick can be made on the Green Run list.

NASA had hopes of launching the uncrewed Artemis I to the Moon this year, although this is looking increasingly unlikely following, firstly, the requirement to repeat the hotfire and, more recently, a delay for the repeat run caused by the need to repair a liquid oxygen valve on the stage.

Should tomorrow's test go well, NASA estimates it will take about a month to refurbish the core stage and its engines before shipping the hardware to the Kennedy Space Center in Florida, where it will finally be mated to the waiting solid rocket boosters.

Still, ongoing delays to Artemis aside, the activation of the stage's computers indicates that the test is imminent. What could possibly go wrong? ®