NASA describes asteroid Bennu as a mountain in the shape of a giant stone drop, and Bennu is carrying a small cargo of gravel that the scientific community is eagerly awaiting. The samples are due to arrive on Earth after 10:00 a.m. (5:00 p.m. Romanian time) on Sunday at a US Army base in the Utah desert. It took almost three years to travel in space.

How much material will the probe bring back from Bennu? The average estimate is 250 grams, plus or minus 100 grams. At best, it will be 351 grams of gravel, and at worst – 149 grams. It will essentially be a cup full of gravel, and we won’t know exactly how much until we analyze the samples.

But even this “worst” case is good because Japan’s Hayabusa2 probe brought back only 5 grams of material from asteroid Ryugu in December 2020.

It should not be forgotten that NASA hoped that the probe would pick up at least 60 grams of material from Bennu, but it turned out that its surface was much less rough, so much more material ended up in the capsule.

On September 24, when the Osiris Rex probe is at a distance of 102,000 km from Earth, it will release a special capsule that will bring samples from Bennu. This capsule will enter the Earth’s atmosphere in four hours and should reach the ground in another 13 minutes.

The scientific community is anxiously awaiting the samples, especially since it involves 250 grams of dust and rock, which is a significant amount.

Asteroid Bennu was discovered in 1999, and a mission to it was announced in 2011.

The mission was launched seven years ago. More precisely, the Osiris-Rex probe was launched in September 2016, arrived at asteroid Bennu two years later and mapped it for a year, and NASA staff then picked the spot where the probe touched the surface in an attempt to take soil samples. . On October 20, 2020, samples were successfully collected.

Asteroid Bennu is almost half a kilometer in diameter and is estimated to have appeared 4.5 billion years ago, shortly after the birth of the solar system. “Asteroids are kind of time capsules floating in space, and they can give us fossil samples from the early days of the solar system,” said Lori Glaze, director of NASA’s Planetary Sciences Division.

It is necessary to overcome several stages. On September 10, the probe changed course after briefly restarting its engines.

The trajectory correction maneuver changed the probe’s speed very little, but without it the cargo collected from Bennu would have passed Earth and been lost.

Before the samples reach Earth, the capsule will have to decelerate for 13 minutes from a speed of more than 44,000 km/h to below 20 km/h so that the rock and soil samples arrive in good condition. A special parachute will also be used for deceleration, and the capsule has a super-resistant heat shield, since the temperature is very high when entering the Earth’s atmosphere.