On September 10th we provided an update on the CAPSTONE mission and below are updated details on the situation.
This is a dynamic operational situation, and the below details are provided based on our best knowledge at time of release. Updates to below information will be provided as we learn more.
- During or shortly after the third trajectory correction maneuver (TCM-3) on September 8th, the spacecraft suffered an anomaly that resulted in the vehicle attitude rates growing beyond the capacity of the on-board reaction wheels to control and counter. The vehicle was attempting to communicate with the ground for approximately 24 hours before any telemetry was recovered. At the point of recovery, the spacecraft was not in a stable configuration, it was not power positive, and the system was experiencing periodic resets.
- Navigation data collected after the anomaly suggests that the maneuver was completed or nearly complete when the anomaly occurred. This means the spacecraft remains on the intended trajectory and on course to the near rectilinear halo orbit at the Moon.
- After the planned TCM-3 maneuver, the spacecraft did not return to ground communications as expected which provided the first indication that there might be an issue.
- Working with limited data, the combined operations team determined it was prudent to declare an operational emergency Thursday evening, September 8th. From this point forward, the teams at the NASA Deep Space Network, Terran Orbital, and Advanced Space have been working around the clock to work the problem, understand what is happening on the spacecraft, and identify options to recover the spacecraft to normal operations.
- Rapid response enabled by the Deep Space Network support and quick thinking by the team at Terran Orbital allowed mission operators to quickly reconfigure the operational state of the spacecraft to stabilize the situation while recovery plans could be further evaluated.
- Based on this exceptional effort and using the limited data available, the operations teams have determined that the spacecraft is in safe mode and appears to have successfully been placed in a stable state. The vehicle is in a rotating orientation that provides partial illumination of the solar panels and results in weak transmission signals from the spacecraft low gain antennas. Without the unique capabilities of the Deep Space Network, the mission team would have little or no information on the status of the spacecraft.
- Modeling of the expected orientation and state of the vehicle into the future suggests it will remain stable. The vehicle is on the orbital trajectory intended and understanding this allows for continued tracking from ground stations well into the future. The vehicle in its current configuration is power positive, meaning that it is generating more power from the solar panels than the system is utilizing.
- The mission operations team is currently focused on recovery plans. These efforts will begin by working to improve the thermal situation of several subsystems including the propulsion subsystem. While work is ongoing to diagnose the cause of the anomaly, the team is preparing the spacecraft to attempt a detumble operation to regain attitude control of the vehicle. This detumble operation was successfully demonstrated after separation from the launch vehicle in July. A successful detumble will result in the vehicle resuming control of its orientation, orienting the solar panels to the Sun to fully charge the batteries of the power used during the detumble. The spacecraft will then orient to the ground and await further instructions. These recovery operations will be further evaluated over the coming days. Recovery timing will be guided by the data and analysis available to maximize the probability of a successful spacecraft operation.
The combined mission team including the Deep Space Network, Terran Orbital, Stellar Exploration, and Advanced Space have been working in a disciplined and collaborative way to stabilize the CAPSTONE spacecraft and prepare for recovery. Many details remain unknown as to the cause of the anomaly and significant risks are continuing to be analyzed.
Everyone on the mission team is focused on recovering from this anomaly and continuing the important objectives of the CAPSTONE mission. As more details are available, they will be provided.
We appreciate the dedicated work of all mission partners involved in these activities and the supportive messages received during this stressful time.