NASA tricks Artemis launch computer by masking data showing a leak
Plus it aborts ISS reboost. Not the greatest start to the week, was it?
NASA engineers had to work fast to avoid another leak affecting the latest Artemis dry run, just hours after an attempt to reboost the International Space Station (ISS) via the Cygnus freighter was aborted following a few short seconds.
The US space agency on Monday rolled the huge Artemis I stack back to its Florida launchpad having worked through the leaks and problems that had beset its previous attempt at fueling the beast in April for an earlier dress rehearsal of the final countdown.
As propellant was loaded into the rocket, controllers noted a hydrogen leak in the quick-disconnect that attaches an umbilical from the tail service mast on the mobile launcher to the core stage of the rocket.
Such a leak would normally trigger a hold in an actual launch. When warming the disconnect then chilling it again to align the seal did not work, the team "developed a plan to mask data associated with the leak," according to NASA. The "mask" – which prevented the data from triggering a hard stop by the ground launch computer – allowed tests to proceed.
The tanks were filled for the first time and other critical operations were ticked off, including a handover from the ground launch sequencer to the automated launch sequencer controlled by the rocket's flight software.
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The wet dress rehearsal ended at 1937 EDT.
The question now is whether NASA reckons it has enough test objectives completed to sign off the stack as ready for its uncrewed launch. If it does, there is a chance the big rocket might launch as summer draws to a close.
Issues also blighted an attempt earlier in the day to reboost the ISS with the engine of Northrup Grumman's Cygnus NG CRS-17 freighter. The test firing – scheduled for Monday at 1020 Central – had been expected to last for just over five minutes but was instead aborted after five seconds. The Cygnus Mission Director at Dulles, Virginia reported that the cause for the abort is "understood" and under review.
A second attempt could occur on June 25, which would lead to Cygnus potentially departing for the station on June 28.
The need to add additional reboost options to the ISS has become more urgent in light of Russia's invasion of Ukraine, subsequent sanctions, and saber rattling by Roscosmos over a future where the Russian agency departs the project. With the retirement of the US Space Shuttle and ESA's ATV, options for reboost are limited. Firings of Russian Progress engines are instead the norm.
Cygnus aside, the non-Russian reboost options are limited for the ISS partners. A propulsion module was proposed as a backup to the functions of the Roscosmos Zvezda Service Module and Progress freighter, but never completed or launched. Another possibility involves the use of SpaceX's Dragon spacecraft. ®