NASA Drops Spacecraft Into Orbit Around Potentially Hazardous Asteroid Bennu (cnet.com)

NASA's asteroid-chasing Osiris-Rex spacecraft has been placed in an orbit around Bennu, an asteroid that drifts through the solar system's asteroid belt between Earth and Mars. "By inserting itself into orbit around Bennu, Osiris-Rex will survey the asteroid from a distance of only about 1 mile (1.75 kilometers) from its center," reports CNET. "Bennu's small size creates an incredibly tiny gravitational force, so maintaining that orbit will require lots of little adjustments, made by NASA and its collaborating organizations." From the report: "The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu's surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars, where gravity is by far the most dominant force," said Dan Wibben, maneuver and trajectory design lead. NASA also released a GIF of the various surveys Osiris-Rex carried out after arriving at Bennu in early December The series of images, captured between Nov. 30 and Dec. 31, helped the team more accurately determine Bennu's mass, which ensured that the orbital insertion would proceed smoothly.

The orbital period, lasting until mid-February, is expected to provide additional details about Bennu's gravity, orientation and spin, along with a better understanding of its mass. All those observations should lead to completing one of the chief objectives for Osiris-Rex: retrieve a sample from Bennu's surface and fly it back to Earth. In 2020, the spacecraft will extend a specially designed arm, called Tagsam, for a brief high-five with the asteroid. The arm will blow nitrogen gas onto the surface of Bennu, kicking up handfuls of dirt, which the spacecraft will fly back to Earth in 2023.

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[Zocalo]

A combination of poor and inaccurate phrasing from TFA. The densest part of belt does indeed lie between Mars and Jupiter but, depending what objects you decide qualify as being part of the asteroid belt, outlier asteroids and those with highly eliptical orbits can be found all the way inside the orbit of Mercury to beyond Saturn. There are also three significant asteroid groupings that lie on the orbit of Jupiter (known as the Greeks, Trojans, and Hildas). Bennu's orbit also happens to just cross that of Earth - it has to really, or there wouldn't be an impact risk - but the majority of it does indeed lie between Earth and Mars, although it's always much closer to Earth's orbit than that of Mars.