NASA Lucy Mission Solar Array Anomaly

La NASA dépanne le vaisseau spatial Lucy à destination d’un astéroïde à des millions de kilomètres

Peu de temps après le lancement de Lucy, l’un de ses panneaux solaires n’a pas réussi à se déployer complètement, mettant la mission en danger. L’animation conceptuelle de cet artiste représente l’anomalie du panneau solaire de Lucy. Crédit : Laboratoire d’imagerie conceptuelle du centre de vol spatial Goddard de la NASA

Juste après le lancement réussi de[{” attribute=””>NASA’s Lucy spacecraft on October 16, 2021, a group of engineers huddled around a long conference table in Titusville, Florida. Lucy was just mere hours into its 12-year journey, but a major unexpected challenge had surfaced for the first-ever Trojan asteroids mission.

Data indicated that one of Lucy’s solar arrays — designed to unfurl like a hand fan — hadn’t fully opened and latched. Since the solar arrays power the spacecraft’s systems, the team had to figure out what to do next.

To troubleshoot the problem, teams from NASA and Lucy mission partners quickly came together. Team members from Lockheed Martin’s Mission Support Area outside of Denver, who were in communication with the spacecraft directly, were on the phone.

Although the conversation was quiet, it was intense. At one end of the room, an engineer sat with furrowed brow, folding and unfolding a paper plate in the same way that Lucy’s enormous circular solar arrays operate.

There were so many unanswered questions. What happened? Was the array open at all? Was there a way to fix it? Without a fully deployed array, would Lucy be able to safely perform the maneuvers needed to accomplish its science mission?

Because Lucy was already speeding on its way through space, the stakes were incredibly high.

La mission Lucy de la NASA se dirige vers le[{” attribute=””>Jupiter Trojans – two swarms of unexplored asteroids trapped in Jupiter’s orbit. Lucy made a picture-perfect launch on October 16, 2021, but when the spacecraft began to unfurl its solar arrays, it encountered an anomaly. One of the arrays failed to fully deploy and latch shut, putting the mission at risk. For months, Lucy’s flight operations team worked meticulously to address the issue and put Lucy back on its solar-powered journey to the Jupiter Trojans.

Within hours, NASA pulled together Lucy’s anomaly response team, which included members from science mission lead Southwest Research Institute (SwRI) in Austin, Texas; mission operations lead NASA’s Goddard Space Flight Center in Greenbelt, Maryland; spacecraft builder Lockheed Martin; and Northrop Grumman in San Diego, solar array system designer and builder.

“This is a talented team, firmly committed to the success of Lucy,” said Donya Douglas-Bradshaw, former Lucy project manager from NASA Goddard. “They have the same grit and dedication that got us to a successful launch during a once-in-a-lifetime pandemic.”

United in their pursuit to ensure Lucy would reach its fullest potential, the team began an exhaustive deep dive to determine the cause of the issue and develop the best path forward.

Given that the spacecraft was otherwise perfectly healthy, the team wasn’t rushing into anything.

“We have an incredibly talented team, but it was important to give them time to figure out what happened and how to move forward,” said Hal Levison, Lucy’s principal investigator from SwRI. “Fortunately, the spacecraft was where it was supposed to be, functioning nominally, and – most importantly – safe. We had time.”

Lucy Solar Panel Deployment Tests

At 24 feet (7.3 meters) across each, Lucy’s two solar panels underwent initial deployment tests in January 2021. In this photo, a technician at Lockheed Martin Space in Denver, Colorado, inspects one of Lucy’s arrays during its first deployment. These massive solar arrays will power the Lucy spacecraft throughout its entire 4-billion-mile, 12-year journey through space as it heads out to explore Jupiter’s elusive Trojan asteroids. Credit: Lockheed Martin

Staying focused during many long days and nights, the team worked through options. To evaluate Lucy’s solar array configuration in real-time, the team fired thrusters on the spacecraft and gathered data on how those forces made the solar array vibrate. Next, they fed the data into a detailed model of the array’s motor assembly to infer how rigid Lucy’s array was – which helped uncover the source of the issue.

At last, they closed in on the root cause: a lanyard designed to pull Lucy’s massive solar array open was likely snarled on its bobbin-like spool.

After months of further brainstorming and testing, Lucy’s team settled on two potential paths forward.

In one, they would pull harder on the lanyard by running the array’s backup deployment motor at the same time as its primary motor. The power from two motors should allow the jammed lanyard to wind in further and engage the array’s latching mechanism. While both motors were never originally intended to operate at the same time, the team used models to ensure the concept would work.

The second option: use the array as it was – nearly fully deployed and generating more than 90% of its expected power.

Peu de temps après le lancement de Lucy, l’un de ses panneaux solaires n’a pas réussi à se déployer complètement, mettant la mission en danger. L’animation conceptuelle de cet artiste représente l’anomalie du panneau solaire de Lucy.

“Chaque route comportait un élément de risque pour atteindre les objectifs scientifiques fondamentaux”, a déclaré Barry Noakes, ingénieur en chef pour l’exploration de l’espace lointain chez Lockheed Martin. “Une grande partie de nos efforts a consisté à identifier des actions proactives qui atténuent les risques dans tous les scénarios.”

L’équipe a tracé et testé les résultats possibles pour les deux options. Ils ont analysé des heures d’images de test de la baie, construit une réplique au sol de l’assemblage du moteur de la baie et testé la réplique au-delà de ses limites pour mieux comprendre les risques de nouvelles tentatives de déploiement. Ils ont également développé un logiciel spécial haute fidélité pour simuler Lucy dans l’espace et évaluer les effets d’entraînement potentiels qu’une tentative de redéploiement pourrait avoir sur le vaisseau spatial.

“La coopération et le travail d’équipe avec les partenaires de la mission ont été phénoménaux”, a déclaré Frank Bernas, vice-président des composants spatiaux et des activités stratégiques de Northrop Grumman.

Après des mois de simulations et de tests, la NASA a décidé d’aller de l’avant avec la première option : une tentative en plusieurs étapes pour redéployer complètement le panneau solaire. À sept reprises en mai et juin, l’équipe a commandé au vaisseau spatial de faire fonctionner simultanément les moteurs de déploiement de panneaux solaires principal et de secours. L’effort a réussi, tirant sur le cordon et ouvrant et resserrant davantage l’utérus.

La mission estime maintenant que le panneau solaire de Lucy est ouvert entre 353 et 357 degrés (sur un total de 360 ​​degrés pour un panneau entièrement déployé). Bien que le réseau ne soit pas complètement verrouillé, il est soumis à des contraintes beaucoup plus importantes, ce qui le rend suffisamment stable pour que le vaisseau spatial fonctionne selon les besoins des opérations de la mission.

Le vaisseau spatial est maintenant prêt et capable de franchir la prochaine grande étape de la mission : une assistance gravitationnelle terrestre en octobre 2022. Lucy devrait atteindre sa première cible d’astéroïdes en 2025.


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