WAS SHINGTON – NASA will not repair a defective electronics unit on the Orion spacecraft recently completed for the Artemis 1 mission after finding that the system as a whole had enough excess.
In a December 17 statement, NASA said it had decided to use “as is” from eight power and data units (PDUs) on the Orion spacecraft, providing communication between the spacecraft’s computers and other components. One of the two redundant channels in one of the two communication cards in that PDU is not working.
Nov. 30. On Nov. 30, NASA announced the problem, saying only that it was “troubleshooting the issue.” The problem was previously reported by The Verge, which said representations by chief contractor Lockheed Martin warned that replacing the PDU could take up to a year, as it is located in the adapter between the crew module and the service module which is now inaccessible. The modules are integrated with each other.
It is assumed at that time that the crew module will be dimmed from the service module, the PDU will be repaired and the two modules will be tested by reconnecting. The alternative option is to complete the repair in just four months, but to reach the PDU you will need to remove the adapter panels, something not designed for hardware.
In a statement on the decision to replace the PDU, NASA did not elaborate on the repair options, but said the risk of damaging the spacecraft during the PDU repair should be completely defective to the unit.
Engineers, the agency said, “have determined that the risk of collateral damage exceeds the risk associated with excessive one-leg loss due to the limited ibility accessibility of these particular busses, the amount of infiltration into overall spacecraft systems and other factors.”
The agency added, “NASA is confident in the overall power and health of the data system, which undergoes thousands of hours of operation and testing,” adding that the PDU in question is still “fully operational.”
Even before the statement, NASA officials were voicing the possibility of extensive repairs to the spacecraft to replace the PDU. “You will get the first report, and the first report will show all the possibilities of a bad situation,” Ken Bowrox, deputy associate administrator of NASA’s Directorate of Human Research and Mission Operations, said during a media briefing on a report on December 7. Science Artemis 3 plans for a lunar landing mission. “At best, we can find that it’s something we can live with.”
At the time of the briefing, Bowrox said NASA was still studying the problem, but was hopeful it would not have a major impact on the Artemis 1 mission. “As we watch it, we don’t really think it will really have an impact on the final schedule,” he said.
With the decision not to replace the PDU, NASA is moving forward with the final approach of the spacecraft. In mid-January, it will proceed to the Kennedy Space Center facility where it was assembled into a multi-payload processing facility there, where it will be refueled and prepared to be installed on the Space Launch system.
The critical route to the Artemis 1 launch, still scheduled for November 2021, is the SLS Core Stage, which is undergoing a series of tests called the Green Run at the Stanislaus Space Center. NASA said it resumed preparations for a fuel test called wet dress rehearsal on December 17, then called the first attempt at that test in early December because liquid oxygen was flowing in the main phase at slightly higher temperatures than desired.
