Capstone again in turmoil on the way to the Moon

Decidedly, fate is bent on the Artemis program.

Definitely, the Artemis program never stops chaining disappointments. In addition to the setbacks of the SLS which remains grounded following technical problems (see our article), it is now the small Capstone probe which has encountered new problems.

Capstone is a small machine that has inherited a central role in the Artemis program; it will serve as a scout to pave the way for the installation of the Lunar Gateway (see our article). This space station will serve as a lunar outpost, with the objective of facilitating the logistics of interplanetary missions. For this reason, the Gateway will be a very important part of the Artemis missions which must bring humans back to the Moon around 2025.

But for that, Capstone will already have to arrive at its destination. And if there is no reason yet to give in to catastrophism, we must all the same admit that the probe has not been very reassuring since its departure, on June 28th. In a statement dated September 12, the agency said the probe had malfunctioned again on September 8.

Capstone is cavorting, and that’s bad news

She was the victim of a computer glitch; he has completely messed up the sensors that allow him to orient himself in space. The latter began to produce inconsistent data, with problematic consequences on the reaction wheel.

The reaction wheel is an essential element of any space vehicle. It is made up of several wheels that each turn around a specific axis at high speed (we talk about flywheels). Its objective is to allow the machine to orient itself in space by varying the speed of rotation of the various wheels (see the principle of conservation of angular momentum).

To determine the correction that it must apply, this device is largely based on the sensors mentioned above. And since these were not working properly, the machine began to spin rapidly and out of control. A very problematic situation, as NASA explains in its press release.

The vehicle attempted to communicate for approximately 24 hours before any data was retrieved. At this point, the vehicle was not in a stable configuration, it was losing electrical charge, and the system was resetting periodically “, explains the agency.

Orientation, energy and temperature problems

A very worrying diagnosis. Because once out of control, the probe can deviate from its trajectory, which reduces the life of the mission. But there is something even more serious; it also means that Capstone cannot orient its photovoltaic panels in such a way as to collect enough solar energy.

In this situation, his energy reserves are gradually dwindling, which is particularly worrying. NASA would indeed be unable to restart Capstone if it ran out of fuel. A loss that would have very important consequences for the rest of the Artemis program.

All the teams in charge of the probe therefore worked tirelessly to resolve this situation. Luckily, they managed to fix some of these issues in time. The press release indicates that the agency has succeeded in regaining control over the software part.

NASA prepares for the most urgent

This allowed engineers to put an end to nuisance resets. They were therefore able to reconfigure the machine to limit energy loss. The probe has started producing more energy than it consumes; there is therefore no longer any imminent risk of permanently losing Capstone.

With the most dangerous symptoms now under control, NASA will have to address other less urgent but equally significant concerns. The temperature of some instruments, for example, is beginning to rise alarmingly. It is not explicitly stated in the press release, but this beginning of overheating may be linked to the fact that NASA had to deactivate certain radiators to preserve energy.

In any case, it will be imperative improve the thermal situation as soon as possible, according to NASA. Otherwise, all the oh so important measurements that the probe must perform could be subject to caution, which would again be problematic for the rest of the program.

Moreover, the machine always turns on itself in a completely anarchic way. This prevents it from recharging its batteries properly and correcting its trajectory. It will therefore be necessary to stabilize Capstone once and for all so that she can continue her mission.

NASA will then be able to move on to the diagnostic phase to precisely determine the origin of the malfunction. Suffice to say that the agency will have its work cut out over the next few days. But the game is worth the candle, knowing the importance of this tiny probe for the rest of the events.

A second major malfunction in two months

This isn’t the first time Capstone has given its designers a cold sweat. On July 4, she gave her operators a first big scare when she completely stopped responding to requests from ground crews. Fortunately, there was more fear than harm. NASA eventually determined the cause of the problem, namely an incorrectly formatted command that caused the radio to be catatonic.

A delicate situation, because if it had lasted, the agency would have had to postpone this maneuver until later. The deviation would then have been greater, which would have forced the probe to expend more fuel to correct its approach trajectory, thus reducing its life expectancy.

Fortunately, NASA managed to reestablish contact two days later, on July 6 — just in time to perform a course correction maneuver (see our article).

It only remains to hope that the Artemis program ends better than it started, between the galleys of Capstone and those of the SLS whose big departure continues to be postponed (see our article).

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