NASA의 Lucy 팀이 달을 발견한 소행성 Polymily

그 전에도 풀어 주다 2021년 10월,[{” 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.”

2020년 1월 9일, Lucy 미션은 공식적으로 7개가 아닌 8개의 소행성을 방문할 것이라고 발표했습니다. 밝혀진 바와 같이, Lucy의 경로를 따라 있는 소행성 중 하나인 Eurybates에는 작은 위성이 있습니다. Lucy의 팀이 위성을 발견한 직후, 그녀와 Eurybates는 태양 뒤로 이동하여 팀이 더 이상 관측하지 못하도록 했습니다. 하지만 2020년 7월 태양 뒤에서 소행성이 나타났고 그 이후로 Lucy의 팀은 허블과 여러 차례에 걸쳐 위성을 관찰할 수 있었고 팀이 위성의 궤도를 정확하게 파악하고 마침내 작은 위성이 접근할 수 있게 되었습니다. 정식 명칭 – Quetta.

Lucy의 수석 연구원은 텍사스주 샌안토니오에 위치한 Southwest Research Institute의 한 지점인 콜로라도 볼더에서 일하고 있습니다. 메릴랜드주 그린벨트에 있는 NASA의 Goddard 우주 비행 센터는 포괄적인 임무 관리, 시스템 엔지니어링, 안전 및 임무 보증을 제공합니다. 콜로라도 리틀턴의 록히드 마틴 우주 공사(Lockheed Martin Space Corporation)가 우주선을 제작했습니다. Lucy는 NASA의 디스커버리 프로그램의 13번째 임무입니다. 앨라배마주 헌츠빌에 있는 NASA의 마샬 우주 비행 센터는 워싱턴에 있는 이 기관의 과학 임무 부서를 위한 발견 프로그램을 관리합니다.