OSIRIS-REx mission: A "time capsule" with 250 grams of the asteroid Bennu will land today in the Utah desert

There is a place in the middle of the Utah desert, in the US, with unusual activity this Sunday. The reason? The imminent arrival to Earth of a true scientific treasure, equivalent to a time capsule. It is expected that around 5 p.m. (Spanish peninsular time) a capsule will land with a quarter of a kilo of material from Bennu, an asteroid about 500 meters in diameter whose composition will be able to be analyzed in detail with the instruments of terrestrial laboratories to investigate at the origin of our solar system.

The samples have been collected by the robotic spacecraft OSIRIS-REx, which after a seven-year adventure, culminates today the mission with an exciting and complex landing before which NASA researchers hold their breath.

“It is the first time that the US is going to bring samples collected from an asteroid to Earth,” says Lucas Paganini, a NASA planetary scientist and one of the members of the team deployed at the US Army base Dugway, in a videoconference interview. a military testing ground near Salt Lake City.

So far only the Japanese have managed to bring material from one of these celestial bodies to Earth, through the robotic mission Hayabusa 2, which in December 2020 brought 5.4 grams of rocks and dust from the asteroid Ryugu to our planet.. The pioneer was the eventful Hayabusa 1 mission, which in 2010 became the first probe to bring particles from an asteroid to Earth for analysis.. But due to various technical problems, instead of obtaining several grams of dust, it brought less than a milligram of particles that were also contaminated by material from the ship itself.

“The requirement of the OSIRIS-REx mission was that it bring 60 grams of Bennu, we know that it has collected 250 grams and it will be the largest sample brought back from an asteroid,” says Paganini, who joined NASA in 2010 after studying Engineering. Electronics and Telecommunications at the University of Mendoza and a doctorate at the University of Freiburg.

The OSIRIS-REx spacecraft took off on September 8, 2016 towards the asteroid Bennu, which it arrived two years later, in August 2018.. He then spent another two studying it, scanning it and making a map that helped scientists locate the place where the spacecraft was to take the samples, which it captured on October 20, 2020.

In the environment of the military base, says this Argentine researcher who joined NASA in 2010, there is a lot of emotion: “We are very excited and it is a joy to be here and share this Sunday with people the arrival of the capsule with the samples from Bennu,” says this scientist, who will participate in the Spanish broadcast of the complicated landing of the capsule.

The interview with Lucas Paganini takes place on Friday. It is cold in the Utah desert, about eight degrees, and although higher temperatures are expected this Sunday, this Argentine scientist explains that regardless of the weather, the capsule will land this Sunday.

It is expected that at 12:42 p.m. (Spanish peninsular time), when the OSIRIS-REx spacecraft is about 102,000 kilometers from Earth, it will release the capsule.. About 20 minutes after landing the container with the samples on the Earth's atmosphere, the spacecraft will turn on its engines to divert its trajectory and begin a new mission, called OSIRIS-APEX (OSIRIS-Apophis Explorer) to explore the asteroid Apophis, to the which will arrive in 2029. Meanwhile, the capsule with the samples will continue on its way to Earth.

“It will descend ballistically, and once it re-enters the Earth's atmosphere, it will take between 13 and 15 minutes to land.”. Through a parachute system it will reduce its speed, as it will travel at more than 40,000 kilometers per hour,” he details.

Specifically, the capsule will enter the Earth's atmosphere at 44,500 kilometers per hour four hours after being released from the spacecraft.. NASA expects this critical phase to occur at 4:42 p.m. and is expected to land 13 minutes later.. The area of the desert in which the capsule will fall comprises an ellipse of about 60 kilometers by 15 kilometers: “There have been many previous studies and calculations, and the mission has been rehearsed a lot, so although the possibilities of error are never zero, they are very low,” he says.

The decisive moment and therefore the most complicated phase will be the release of the parachutes so that the capsule decelerates: “If they did not release, the safety of the capsule could be compromised because it would be a very strong landing that could damage it,” he warns.. The capsule, adds Paganini, “has a special heat shield that allows the samples to be maintained at a stable temperature” and not be altered during re-entry into the atmosphere.

Recreation of one of the parachutes that will be deployed during the landing of the capsule

“We know that the capsule contains pristine material and now we are going to be able to study it with the high-precision instruments that we have in laboratories on Earth but that we cannot have on spacecraft,” says the NASA researcher.

Therefore, the treatment given to the container once it lands is essential to keep the samples in perfect condition.. Around a hundred people and two helicopters are part of the deployment to recover the capsule and broadcast its arrival.. The sample rescue operation will begin with rapid action to recover them as soon as possible and reduce the chances of the container being contaminated upon contact with the earth's surface.. Military and NASA personnel will place the capsule in a metal box and wrap it in several sheets of a non-reactive plastic material first, and then in a tarp.

A harness will then be placed over the box to secure it to a cable attached to a helicopter, which will fly it to a mobile clean room at the Utah base to check that it is in good condition.. In this clean room they will open the capsule, remove the container with the sample and prepare it so that on Monday it will be transferred to NASA's Johnson Space Center in Houston, which will be where most of the samples will be kept.

NASA's plan, says Paganini, is that 25% of the material will be distributed among the 233 scientists on the mission.. On the other hand, the Canadian Space Agency will keep 4% and the Japanese agency, JAXA, will be given 0.5%.. A small portion of the sample will also be stored in White Sands, New Mexico, for safekeeping.. The rest, approximately 70%, “will be preserved for posterity, for when better instruments become available and for future scientists to study,” says Paganini.

Why is it so important to study asteroids? “They are fossils or time capsules, the remains of the formation of planets and moons that took place 4.6 billion years ago.. These challenges allow us to understand how they were formed and in addition, we have theories that maintain that asteroids or comets could have brought to Earth the essential elements for the beginning of life, such as carbon, hydrogen, oxygen or even water,” says this scientist. from NASA.

The other important aspect, he adds, is planetary defense: “The study of these components allows us to better understand their composition in the face of possible asteroids that may have a dangerous course for Earth,” he points out.