NASA has long planned to study Bennu in more detail, a small asteroid (just over 500 meters in diameter) that scientists believe has survived almost intact since the solar system was formed.
In September 2016, the US space agency sent the Origins probe, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) to the asteroid. The ship arrived in Bennu in early December 2018 and after a few days discovered the presence of hydroxyl groups in the asteroid’s minerals, which means that there was water on the larger object that Bennu was once a part of. On the last day of 2018, OSIRIS-REx went into orbit around the asteroid and became the first artificial satellite ever of such a small space object.
The probe took a sample from the surface of Bennu, but there is a problem
Last week, the OSIRIS-REx probe lowered its orbit and collected a rock sample from the asteroid’s surface in just 6 seconds of contact. This undoubtedly important part of the mission was successful, but now NASA has a big problem. The agency said the probe’s boom had adequately secured the sample and caused the stones from Bennu to escape into space.
The material moving away from the boom was captured in the images sent by the probe. NASA scientists combined three selected frames into a short video showing the motion of the pebble.
NASA researchers suspect that the cause of the problem was that the tank protection in the boom was not closed, which may have been blocked by larger parts of the collected material. However, the sample is so large that – despite the problem – researchers should be able to hide the rest of it in the Sample Return Capsule (SRC), a capsule that protects loose stones when the OSIRIS-REx probe returns.
The US agency has already taken some measures to minimize boom movements that lead to material emissions. For this purpose, among other things, the measurement of the mass of the collected sample planned for Saturday (scientists only assume that it is over 60 grams so far) and the launch of the probe’s control motors were abandoned.
Priority for researchers is now to secure the material in the SRC, and NASA is to soon inform about the success (or not) of this part of the mission. If all goes as planned, the OSIRIS-REx (with Bennu regolith on board) will land on Earth on September 24, 2023 – after seven years in space.