Der Mond wurde vom Lucy-Team der NASA um den Asteroiden Polymily herum entdeckt

Lucy wird Jupiters trojanische Asteroiden erforschen, von denen angenommen wird, dass sie „Fossilien der Planetenentstehung“ sind. Bildnachweis: Goddard Space Flight Center der NASA

sogar davor Veröffentlichung Im Oktober 2021,[{“ attribute=““>NASA’s Lucy mission was already on course to break records by visiting more asteroids than any previous mission. Now, the mission can add one more asteroid to the list, after a surprise result from a long-running observation campaign.

Lucy’s science team discovered on March 27 that the smallest of the mission’s Trojan asteroid targets, Polymele, has a satellite of its own. On that day, Polymele was expected to pass in front of a star. This would allow the team to observe the star blink out as the asteroid briefly blocked, or occulted, it. The Lucy team planned to measure the location, size, and shape of Polymele with unprecedented precision while it was outlined by the star behind it. To do so, they spread 26 teams of professional and amateur astronomers across the path where the occultation would be visible.

A graphic showing the observed separation of asteroid Polymele from its discovered satellite. Credit: NASA’s Goddard Space Flight Center

These occultation campaigns have been enormously successful in the past, providing valuable information to the mission on its asteroid targets, but this day would hold a special bonus.

We were thrilled that 14 teams reported observing the star blink out as it passed behind the asteroid. However, as we analyzed the data, we saw that two of the observations were not like the others,” said Marc Buie, Lucy occultation science lead at the Southwest Research Institute, which is headquartered in San Antonio. “Those two observers detected an object around 200 km (about 124 miles) away from Polymele. It had to be a satellite.”

A graphic showing the observed separation of asteroid Polymele from its discovered satellite. Credit: NASA’s Goddard Space Flight Center

Using the occultation data, the scientists determined that this satellite is roughly 3 miles (5 km) in diameter, orbiting Polymele, which is itself around 17 miles (27 km) along its widest axis. The observed distance between the two bodies was approximately 125 miles (200 km).

Following planetary naming conventions, the satellite will not be issued an official name until the team can determine its orbit. As the satellite is too close to Polymele to be clearly seen by Earth-based or Earth-orbiting telescopes – without the help of a fortuitously positioned star – that determination will have to wait until Lucy approaches the asteroid in 2027, unless the team gets lucky with future occultation attempts before then.

At the time of the observation, Polymele was 480 million miles (770 million km) from Earth. Those distances are roughly equivalent to finding a quarter on a sidewalk in Los Angeles – while trying to spot it from a skyscraper thousands of miles away in Manhattan.

Using the occultation data, the team assessed that this satellite is roughly 3 miles (5 km) in diameter, orbiting Polymele, which is itself around 17 miles (27 km) along its widest axis. The observed distance between the two bodies was about 125 miles (200 km). Credit: NASA’s Goddard Space Flight Center

Asteroids hold vital clues to deciphering the history of the solar system – perhaps even the origins of life. Solving these mysteries is a high priority for NASA. The Lucy team originally planned to visit one main belt asteroid and six Trojan asteroids, a previously unexplored population of asteroids that lead and follow Jupiter in its orbit around the Sun. In January of 2021, the team used the Hubble Space Telescope to discover that one of the Trojan asteroids, Eurybates, has a small satellite. Now with this new satellite, Lucy is on track to visit nine asteroids on this remarkable 12-year voyage.

“Lucy’s tagline started out: 12 years, seven asteroids, one spacecraft,” said Lucy program scientist Tom Statler at NASA Headquarters in Washington. “We keep having to change the tagline for this mission, but that’s a good problem to have.”

Am 9. Januar 2020 gab die Lucy-Mission offiziell bekannt, dass sie nicht sieben, sondern acht Asteroiden besuchen werde. Wie sich herausstellt, hat Eurybates, einer der Asteroiden auf Lucys Weg, einen kleinen Satelliten. Kurz nachdem Lucys Team den Satelliten entdeckt hatte, bewegten sie und Eurybates sich hinter die Sonne und hinderten das Team daran, ihn weiter zu beobachten. Im Juli 2020 tauchten jedoch Asteroiden hinter der Sonne auf, und seitdem konnte Lucys Team den Satelliten mehrfach mit Hubble beobachten, wodurch das Team die Umlaufbahn des Satelliten genau bestimmen und dem kleinen Satelliten schließlich den Zugang ermöglichen konnte. Offizieller Name – Quetta.

Lucys leitender Ermittler arbeitet in Boulder, Colorado, einer Zweigstelle des Southwest Research Institute mit Sitz in San Antonio, Texas. Das Goddard Space Flight Center der NASA in Greenbelt, Maryland, bietet umfassendes Missionsmanagement, Systemtechnik, Sicherheit und Missionssicherung. Die Lockheed Martin Space Corporation aus Littleton, Colorado, baute das Raumschiff. Lucy ist die dreizehnte Mission im Discovery-Programm der NASA. Das Marshall Space Flight Center der NASA in Huntsville, Alabama, verwaltet das Entdeckungsprogramm für das Science Mission Directorate der Agentur in Washington.