In 2008, during OS7’s approach to Earth on February 2, the Deep Space Network’s planetary radar collected the first detailed images of the stadium-sized asteroid. On February 2, a large asteroid safely passed Earth at a distance of approximately 1.8 million miles (2.9 million kilometers, or 7.5 times the distance between the Earth and the Moon).

There was no risk of asteroid 2008 OS7 hitting our planet, but scientists at NASA’s Jet Propulsion Laboratory in Southern California used a powerful radio antenna to better determine the size, rotation, shape and surface details of this near-Earth object (NEO). . . Before this approach, asteroid 2008 OS7 was too far from Earth to be imaged by planetary radar systems.

Discovery and observation

The asteroid was discovered on July 30, 2008, during routine ESO search operations by the NASA-funded Catalina Sky Survey, headquartered at the University of Arizona in Tucson. After its discovery, observations of the amount of light reflected from the asteroid’s surface showed that it was approximately 650 to 1,640 feet (200 and 500 meters) wide and rotated relatively slowly, making one revolution every 29 and a half hours.

The rotation period of 2008 OS7 was determined by Petr Pravec of the Institute of Astronomy of the Czech Academy of Sciences in Ondřejov, Czech Republic, who observed the asteroid’s light curve, or how the brightness of an object changes over time. As an asteroid rotates, the change in shape changes the brightness of the reflected light that astronomers see, and these changes are recorded to understand the asteroid’s rotation period.

Radar image reveals details

During the close approach on February 2, the JPL radar team used the powerful 70-meter radar antenna at the Goldstone Solar System’s Deep Space Network facility near Barstow, California, to image the asteroid. Scientists found that its surface has a mixture of rounded and more angular areas with a slight concavity. They also found that the asteroid was smaller than previously thought (about 150 to 200 meters) and confirmed its extremely slow rotation.

Potentially dangerous but safe now

Goldstone’s radar observations also provided important measurements of the asteroid’s distance from Earth during its passage. These measurements could help scientists from NASA’s Center for Near-Earth Object Studies (CNEOS) refine calculations of the asteroid’s orbital path around the Sun. Asteroid 2008 OS7 orbits the Sun every 2.6 years and passes from the orbit of Venus to the orbit of Mars at its farthest point.

CNEOS, operated by JPL, calculates the orbit of each known NEO to assess potential collision hazard. Because of its orbit’s close proximity to Earth’s orbit and its size, 2008 OS7 is classified as a potentially hazardous asteroid, but the close approach on February 2 will be the closest approach to our planet in at least 200 years.

While NASA reports UFOs of all sizes, Congress has authorized the agency to detect and track objects 460 feet (140 meters) or larger that could cause serious damage to Earth if they collided with our planet.

The Goldstone Solar System Radar Group and CNEOS are supported by NASA’s Near-Earth Object Observation Program within the agency’s Planetary Defense Coordination Office at the agency’s Washington headquarters. The Deep Space Network receives programmatic oversight from the Space Communications and Navigation (SCaN) Program Office within the Space Operations Mission Directorate, also located at the agency’s headquarters.