The great close asteroid 2003 SD220 approach provided an excellent opportunity to get detailed radar images of shapes and surfaces and improve understanding of orbits.
The asteroid reached its maximum approach of 2.9 million kilometers on December 22, approaching 400 years and approaching 2070, although nothing else was in danger for our planet.
The radar image reveals a small asteroid with a length of over 1.6 kilometers and a shape similar to the exposed part of the stream.
They obtained observations from NASA's 70-meter antenna and observations at Goldstone, a 100-meter Greenbank telescope, from December 15 to 17. The National Science Foundation, and the 305-meter antenna at Arecibo Observatory in Puerto Rico.
The Greenbank telescope received a powerful microwave signal known as the "bistatic radar configuration" by planet radar Arecibo, funded by Goldstone or NASA. Using a telescope to transmit and receive another can generate more detail than a telescope, and obtaining such a slow approaching and rotating asteroid radar image is a valuable technique.
"The radar image is similar to the unprecedented level of detail and the overflight of the spacecraft," said Lance Benner of the Jet Propulsion Laboratory in Pasadena, California. Gold Stone.
"The most prominent feature of the surface is a noticeable ridge that appears to partially wrap around the asteroid near one end, which rises about 100 meters above the surrounding terrain. And the rock also shows a group of dark circles that can be craters near the right edge. "
The images confirm that the asteroids and previous Arecibo radar images have been confirmed from previous sunlight measurements reflected from the images. 2003 The rotation period of the SD220 is very slow, approximately 12 days. It also looks like a complex rotation similar to an incompletely started football. Known as a "non-main axis" rotation, this material is rare among asteroids near the Earth, and most of them rotate about the shortest axis.
The detail of this image, which had a resolution of 3.7m per pixel, was 20 times more delicate and farther than it was obtained from the asteroid approach to Earth three years ago. The new radar data will provide important constraints on the distribution of density inside the asteroid, and you will find that there are few asteroids on Earth.
Edgar Rivera-Valentin, a USRA scientist, said, "The new details we have found up to 2003 SD220's geology will allow us to reconfigure the shape and rotation of our system, just like Bennu, the goal of the OSIRIS-REx mission." LPI in. "The detailed reconstruction of the form allows us to better understand how this small body has formed and evolved."
The 2003 SD220 asteroid was discovered on September 29, 2003 by astronomers at the Lowell observatory. It is classified as a "potentially dangerous asteroid" because of its size and proximity to Earth's orbit. However, these radar measurements have confirmed that the 2003 SD220 has improved its understanding of orbits and is not a threat to future impacts on Earth.