NASA Will Pluck An Asteroid Sample From Bennu's Nightingale Site

Days after it revealed its final four candidate sites for the future asteroid sample mission involving OSIRIS-REx, NASA has announced which of the four it has chosen: Nightingale. This destination will, hopefully, be the source of a physical sample collected by the OSIRIS-REx spacecraft, which has spent months circling a large space rock called Bennu. This asteroid turned out to be surprisingly rocky, making the site selection a tricky process for scientists.READ: The four best sample sites on asteroid Bennu

Bennu, it turns out, is a very rocky asteroid and this is a problem for NASA. The OSIRIS-REx spacecraft will get very close to the asteroid's surface in order to collect a sample, but this will only work if researchers pick a site that, A) contains fine enough particles for the spacecraft to collect, and B) doesn't have any nearby boulders or other rocks that the spacecraft may smack into.

OSIRIS-REx has sent many pictures of the asteroid from all angles back to NASA, where a team has studied the content to figure out the ideal sample collection sites. Four final candidate sites were revealed earlier this month, each with its own potential benefits and downsides. Of those four, NASA says Nightingale gets the honor of being the primary sample site.

According to the space agency, Nightingale has the greatest quantity of fine-grained material out of the four sites, plus the spacecraft can safely and easily access this site compared to the others. The site resides within a crater measuring 460ft across, according to NASA, which says the material in this northern crater is likely 'well-preserved.'

With that said, Nightingale isn't the perfect selection site. NASA says the actual area where the sample will be collected measures around 52ft across, whereas the mission was aiming for a sample site measuring 164ft in diameter. As well, there's one large boulder (it's the size of a building) on the crater's rim where it may be a risk to the spacecraft.

Assuming Nightingale doesn't work out in the end, NASA has chosen Osprey as the backup site.