And expectations are high.

Tomorrow is the day when spacecraft OSIRIS-REx will descend to the surface of asteroid Bennu to collect some pristine material. Expectations are high. Because Bennu is probably an alien accumulation of original remnants of the formation of our solar system. And so researchers are eager to take a closer look at that material.

Sampling
The place where it is all about to happen is de Nightingale-krater. According to NASA, this is where the largest amount of fine-grained (and therefore easy to collect) material can be found. Despite the fact that OSIRIS-REx has been practicing sampling for some time, it promises to be an exciting venture tomorrow. First, the OSIRIS-REx thrusters will be started up and the probe will be gently pushed out of orbit and closer to Bennu. Once the spacecraft is on its way to its target, the team will rely on the so-called ‘hazard map’; a detailed representation of areas within the sampling site that could pose a risk due to the presence of large rocks and uneven terrain. Because of course the probe must be prevented from hitting these stones. When the coast is clear, OSIRIS-REx will descend completely to Bennu’s surface, hit it for about ten seconds, fire a charge of nitrogen to wipe the surface so that the necessary samples can then be collected. The probe does this with the so-called Touch-and-Go Sample Acquisition Mechanism (TAGSAM); a three-meter-long sampling arm. After that, the probe will take off again quickly.

The promising mission to sample Bennu – a planetoid many millions of kilometers from Earth – is anything but a cinch. “In fact, Bennu is nowhere near the sandy surface we had hoped and expected,” said researcher Thomas Zurbuchen on behalf of NASA. When the spacecraft delivered the first detailed footage of Bennu, it surprised both the mission team and the general public by revealing a rocky surface strewn with boulders the size of houses.

Images
Yet this does not stop the team. However, they will keep a close eye on the descent with the sampling camera on board the spacecraft, the SamCam. “We will then see whether we were tilted, whether gas was blown to the side and whether enough material was stirred,” says mission investigator Dante Lauretta. “In addition, we can see exactly where the probe has landed, which we can then compare with the sampling map.”

What do we know about Bennu?
In the past two years that OSIRIS-REx orbits around Bennu, he has already made some interesting discoveries. Although Bennu – a diamond-shaped boulder floating in space – doesn’t seem so special at first glance, researchers have discovered that appearances are deceptive. For example, it appears that carbonaceous organic matter is widespread on the asteroid’s surface, including in the Nightingale Crater. In addition, researchers showed that Bennu molecules can be found that contain oxygen and hydrogen atoms. In addition, researchers found that regolith, found in Nightingale Crater, has only recently been exposed to the harsh conditions of the Universe. This means that the mission will collect some of the most pristine material on the asteroid and return it to Earth. Scientists also found that Bennu is home to dark and rough, as well as bright and smooth stones. The dark stones are slightly weaker and more porous. These different rocks may have formed at different depths on Bennu. Finally, Bennu would just agree can be very old, it turns every century a little faster on its own axis and it turns out in the afternoon throw away your own material.–

During a week, the team will assess whether enough samples have been collected. Various methods will be used for this. Among other things, OSIRIS-REx will perform a maneuver, extending its sampling arm and slowly rotating it, so that researchers will be able to measure the change in mass attributable to the collected material by means of the TAGSAM compared to previous measurements. . “We are looking for a 90 percent chance that we have collected 60 grams or more of material,” says Lauretta. “If it is less, we will talk to NASA to assess the status of the spacecraft and its capability for a possible second sampling.” Since the spacecraft is equipped with three bottles of nitrogen gas, OSIRIS-REx could make a second attempt if too little material was collected during the first sampling.

The hope is of course that the sampling will go entirely according to plan tomorrow and that sufficient material can be collected. These samples will then be returned to Earth on September 24, 2023. And hopefully this will help us better understand the origins of our solar system.