In recent days, an unofficial plan had emerged that could lead to the modification of the Artemis III mission. Bill Nelson (NASA administrator) said that these were just rumors and the agency was continuing with the plan announced previously. In the second part of 2025 there could therefore be the first human crew mission of this space program which will take four astronauts around the moon and then return to Earth aboard the Orion capsule. The moon landing is currently scheduled for 2026, but it is very likely that it will be postponed by at least a year (or possibly more).
In the past few hours theOffice of the Inspector General (OIG) released a new report indicating i problems to be resolved before the launch of the Artemis II mission to ensure minimal risk to the crew. In particular the OIG focused on problems relating to Orion capsule which was employed during the first uncrewed mission to lunar orbit.
According to the report, three anomalies were found in the spacecraft “pose significant risks to the safety of the crew”. The OIG focused on the heat shield problemsto the explosive bolts positioned on the latter and to the distribution of energy. NASA has identified over one hundred areas where the ablative material for thermal protection of the heat shield (called Avcoat) has worn differently than expected. Engineers are currently investigating how to fix the problem by changing the design of the Orion’s heat shield or by modifying the reentry trajectory.
In addition, the bolts that provide separation between the spacecraft and the service module have unexpectedly melted and worn, creating a gap that would lead to increased heat in the area. To solve the problem in view of Artemis II A change has been made to the bolt design and additional thermal protection will be added in the gaps left by post-separation bolts.
Lastly, 24 anomalies were recorded in the distribution of electricity for the power system. The main reason would be related to radiation and a change to the software and other alternative solutions were thought of for the second mission. However, the OIG believes that permanent solutions are needed to reduce risks.
In detail, it ablative heat shield in Avcoat of Orion space capsule it would break in several areas with the fragments then being lost rather than being consumed by melting as per design. This may not provide adequate thermal protection leading to mission failure. Furthermore, if the fragments detached during the opening of the parachutes, the latter could be hit and therefore damaged (which however did not occur with Artemis I).
Engineers are conducting ground tests to recreate the problem. Currently it has been possible to reproduce the loss of material but not the overall response of the heat shield experienced during the flight. Furthermore, it is not possible to replicate the exact temperatures and speeds that would occur during a re-entry. As an example, Orion’s return speed from a lunar mission is 40% higher than that of a Crew Dragon returning from a mission from the ISS. Further innovations will be announced at the end of the tests scheduled for the first half of 2024.
As regards the bolts, these are four and positioned in the heat shield of the capsule. During the reentry phases the bolts are activated, separating the capsule with the crew from the service module (with the latter burning in the atmosphere). The bolts are surrounded by Avcoat and an insulating filler without affecting their function.
During Artemis I, three of the four bolts experienced void zones which led to increased heat in the innermost zone resulting in melting and erosion. This could lead to a loss of heat shield integrity by allowing very hot gases to penetrate to the lower areas and loss of the vehicle. The bolts for the Orion capsule from the Artemis II mission they were installed in September 2023 and further testing is underway. A final judgment is expected in mid-2024 and related changes will be applied in the coming months.
The report then indicates the problems related to the distribution of electricity but also the damage to the Mobile Launcher 1 (ML-1) during the take-off of NASA SLS. There would also have been losses in communication between the Deep Space Network and the capsule which will be evaluated to prevent this from recurring during manned missions. The latter are considered “minor issues” compared to those highlighted by Orion although it will still be necessary to find a solution to resolve them.
