NASA has selected four potential sites for its OSIRIS-Rex spacecraft to collect samples from the surface of the asteroid Bennu. This is NASA’s first asteroid sample return mission. The final two sites for sample collection will be decided by December 2019. According to NASA’s statement, one will be the primary site, while the second one will be the backup site for collecting samples from asteroid Bennu. The four candidate sample sites on Bennu have been named as Nightingale, Kingfisher, Osprey, and Sandpiper, all names after birds native to Egypt.
  1. The OSIRIS-REx spacecraft’s name stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx)
  2. It landed on Bennu’s surface since on December 3, 2018, where it began looking for sites from which to take samples. The sample collection is scheduled for the latter half of 2020. It will return the asteroid samples to Earth on September 24, 2023.
  3. Asteroid Bennu is the smallest body in the solar system to be orbited and surveyed by a spacecraft at close range, according to NASA. OSIRIS-REx will begin detailed analyses of the four candidate sites later in the fall.
  4. According to NASA, images taken from the OSIRIS-Rex spacecraft have shown that “Bennu has an especially rocky terrain. 
  5. This will make sample collection tougher than previously thought as the sample material has to be “fine enough – less than 1 inch (2.5 cm) diameter” in order for the “spacecraft’s sampling mechanism to ingest it.
  6. While the first phase of reconnaissance missions will take place in the fall of 2019, the second and third stages of reconnaissance will begin in early 2020. 
  7. In these phases, the spacecraft will perform passes over the final two sites. OSIRIS-REx will fly at lower altitudes and take even higher resolution observations of the surface. This will help the agency identify features such as groupings of rocks to help navigate the surface for sample collection.
  8. NASA’s mission will spend another four months studying the four candidate sites in detail. Although OSIRIS-REx was designed to collect a sample from an asteroid with a beach-like area, the extraordinary in-flight performance to date demonstrates that we will be able to meet the challenge that the rugged surface of Bennu presents.
The four sites
  1. The first is Nightingale, which is the northern-most site. It is set in a small crater encompassed by a larger crater and contains mostly fine-grain, dark material. It  has the lowest reflection and surface temperature among all the four sites.
  2. The second site is Kingfisher, which is located in a small crater near Bennu’s equator at 11 degrees north latitude. The site itself is free of large rocks and has the strongest spectral signature for hydrated minerals.
  3. The third site is Osprey, which is also located in Bennu’s equatorial region at 11 degrees north latitude. There are several possible sampling regions within the site. According to NASA, it has strongest spectral signature of carbon-rich material out of all the four sites.
  4. Sandpiper is the fourth site. This one is located in Bennu’s southern hemisphere at 47 degrees south latitude and is in a relatively flat area on the wall of a large crater. NASA says that hydrated minerals are also present on this site, indicating presence of unmodified water-rich material.

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