NASA's planetary radar took some pictures of the slowly rotating asteroid 2008 OS7 for the purpose of observation.

 

In the lead-up to its close encounter with Earth on Feb. 2, asteroid 2008 OS7 was meticulously observed through a series of images taken by the formidable 230-foot Goldstone Solar System Radar antenna near Barstow, California.

As asteroid 2008 OS7 approached Earth on Feb. 2, NASA's Deep Space Network planetary radar provided unprecedented detailed images of the stadium-sized celestial body. Despite its safe distance of about 1.8 million miles – roughly 7 ½ times the Earth-Moon distance – there was no threat of impact. Scientists at NASA's Jet Propulsion Laboratory in Southern California utilized a potent radio antenna to analyze the size, rotation, shape, and surface characteristics of this near-Earth object (NEO). Prior to this close encounter, the asteroid had been beyond the reach of planetary radar systems for imaging.

Unveiled on July 30, 2008, the asteroid came into view during routine searches for Near-Earth Objects (NEOs) conducted by the NASA-funded Catalina Sky Survey, based at the University of Arizona in Tucson. Post-discovery, meticulous observations of the reflected light from the asteroid's surface disclosed its dimensions, estimating a width ranging from 650 to 1,640 feet (200 to 500 meters). Additionally, the celestial body exhibited a relatively leisurely rotation, completing one revolution approximately every 29 ½ hours.

Petr Pravec, situated at the Astronomical Institute of the Czech Academy of Sciences in Ondřejov, Czech Republic, played a pivotal role in establishing the rotational period of 2008 OS7. This determination involved observing the asteroid's light curve, depicting variations in its brightness over time. As the asteroid rotates, alterations in its shape cause fluctuations in the reflected light observed by astronomers. These changes are meticulously recorded to unravel the precise period of the asteroid's rotation, providing valuable insights into its dynamic characteristics.

Observations of Asteroid 2008 OS7 by Goldstone Radar.

On Feb. 2, the Jet Propulsion Laboratory's radar group employed the formidable 230-foot Goldstone Solar System Radar antenna dish at the Deep Space Network's facility near Barstow, California, to capture detailed images of the approaching asteroid. Analysis revealed a diverse surface, featuring a combination of rounded and angular regions, including a small concavity. Contrary to prior estimates, the asteroid's revised size was determined to be approximately 500 to 650 feet (150 to 200 meters) wide, and its rotation was confirmed to be exceptionally sluggish.

In addition to imaging, the Goldstone radar observations played a crucial role by furnishing essential measurements of the asteroid's distance from Earth during its passage. These measurements are instrumental for scientists at NASA's Center for Near Earth Object Studies (CNEOS) to enhance precision in calculating the asteroid's orbital trajectory around the Sun. Orbiting the Sun every 2.6 years, asteroid 2008 OS7 traverses from within the orbit of Venus to its farthest point beyond the orbit of Mars.

Managed by JPL, NASA's Center for Near Earth Object Studies (CNEOS) diligently calculates the orbits of every known Near-Earth Object (NEO), offering vital assessments of potential impact hazards. Owing to its orbit's proximity to Earth and its size, asteroid 2008 OS7 is categorized as a potentially hazardous asteroid. Notably, the close approach on Feb. 2 represents the closest encounter it will have with our planet for at least the next 200 years.While NASA monitors NEOs across various sizes, Congress has mandated the agency to focus on detecting and tracking objects sized 460 feet (140 meters) and larger. This emphasis addresses the potential for significant ground damage in the event of an impact on Earth.

Backing the efforts of the Goldstone Solar System Radar Group and CNEOS, NASA's Near-Earth Object Observations Program operates under the Planetary Defense Coordination Office at the agency's headquarters in Washington. The program ensures systematic surveillance and analysis of potential impact threats. The Deep Space Network, integral to these initiatives, is subject to programmatic oversight by the Space Communications and Navigation (SCaN) program office within the Space Operations Mission Directorate, also headquartered in Washington. For further insights into planetary radar, CNEOS, and near-Earth objects, additional information can be accessed at NASA's Asteroid Watch.