(The green circle shows the location of the Dimorphos asteroid, which orbits the larger asteroid, Didymos, seen here as the bright line across the middle of the images. The images show the Didymos and Dimorphos binary asteroid system obtained from radar facilities at NASA Jet Propulsion Laboratory’s Goldstone planetary radar in California and the National Science Foundation’s Green Bank Observatory in West Virginia.Shown at left are Oct.4, 2022, observations from Goldstone observations; at right are combined Goldstone and Green Bank observations from Oct.9, 2022. Credits: NASA/Johns Hopkins APL/JPL/NASA JPL Goldstone Planetary Radar/National Science Foundation’s Green Bank Observations)
(The green circle shows the location of the Dimorphos asteroid, which orbits the larger asteroid, Didymos, seen here as the bright line across the middle of the images. The blue circle shows where Dimorphos would have been had its orbit not changed due to NASA’s DART mission purposefully impacting the smaller asteroid on Sept. 26, 2022. The images show the Didymos and Dimorphos binary asteroid system obtained from radar facilities at NASA Jet Propulsion Laboratory’s Goldstone planetary radar in California and the National Science Foundation’s Green Bank Observatory in West Virginia. Shown at left are Oct. 4, 2022, observations from Goldstone observations; at right are combined Goldstone and Green Bank observations from Oct. 9, 2022.Credits: NASA/Johns Hopkins APL/JPL/NASA JPL Goldstone Planetary Radar/National Science Foundation’s Green Bank Observatory)
(This chart offers insight in to data the DART team used to determine the orbit of Dimorphos after impact – specifically, small reductions in brightness due to eclipses of Didymos and Dimorphos. The new observations show the Dimorphos eclipses occur at different times (green arrows) than if the period were unchanged (gray arrows). The top timeline shows observations the DART team used to determine Dimorphos’ new orbital period, with two sets of that data (from Sept. 29, 2022, and Oct. 4, 2022) shown in detail. The observed decreases in relative brightness for each night’s dataset correspond to Dimorphos eclipses from a new orbital period of 11 hours and 23 minutes – demonstrating that the eclipse timing differs from pre-impact period of 11 hours and 55 minutes. Credit: NASA/Johns Hopkins APL/Astronomical Institute of the Academy of Sciences of the Czech Republic/Lowell Observatory/JPL/Las Cumbres Observatory/Las Campanas Observatory/European Southern Observatory Danish (1.54-m) telescope/University of Edinburgh/The Open University/Universidad Católica de la Santísima Concepción/Seoul National Observatory/Universidad de Antofagasta/Universität Hamburg/Northern Arizona University)
(This movie uses images fr om the LUKE camera on ASI’s LICIACube, captured just after the impact of NASA’s Double Asteroid Redirect Test, or DART, spacecraft with the asteroid Dimorphos on Sept. 26, 2022. The video begins with LICIACube around 500 miles away from the asteroid, passes by, and then continues to around 200 miles away. The video clearly shows the ejection of material streaming off of Dimorphos due to the impact.Credits: ASI/NASA)
과학자들이 지상 관측을 통해 DART에 충돌한 데모포스의 공전 주기가 32분이나 바뀐 것을 확인했습니다. 9월 26일에 충돌한 DART의 목표는 데모 포스의 공전 주기를 73초 이상 바꾸는 것이었습니다.
NASA JPL의 골드스톤 행성 레이더와 미국 국립과학자딘의 그린뱅크 천문대 전파망원경(Goldstone planetary radarin California and the National Science Foundation’s Green Bank Observatory)은 지구에서 1100만㎞ 떨어진 디스모스와 데모포스를 관측했습니다.
10월 4일과 9일에 얻은 레이더 이미지는 데모 포스가 예상 위치에서 상당히 벗어난 궤도를 공전하고 있음을 보여줍니다. 원래 11시간 55분 주기로 디모스를 공전하던 디모포스의 공전 주기가 11시간 23분으로 바뀌면서 예상 위치에서 상당히 벗어난 곳에서 관측된 것입니다. 측정 오차가 2분 정도인 것을 감안하면 상당히 유의미한 변화가 생긴 것입니다. 미국 이외의 나라에서 측정한 내용도 마찬가지였습니다.
생각보다 큰 변화의 이유가 무엇인지, 그리고 충돌 당시 분출된 물질의 특징은 무엇인지 알기 위해 과학자들은 계속 관측을 이어가고 있습니다. 그리고 시속 22530km의 속도로 충돌한 DART가 데모포스에 어떤 변화를 일으켰는지 알기 위해 5년 후 유럽우주국의 헤라 탐사기가 이 소행성을 방문할 예정입니다. 과연 어떤 충돌의 흔적이 남아있을지 궁금합니다.
참고
https://www.nasa.gov/feature/nasa-dart-imagery-shows-changed-orbit-of-target-asteroid
https://www.nasa.gov/press-release/nasa-confirms-dart-mission-impact-changed-asteroid-s-motion-in-space
#태양계, #디모스, #디모포스, #DART