Next Sunday a capsule released by the NASA spacecraft OSIRIS-REx will descend on the Utah desert, in the United States, transporting the samples that the mission collected from the surface of the asteroid Bennu in 2020. This is the first time that the North American space agency carries out a similar mission.
On July 26, mission operators began modifying the trajectory of OSIRIS-REx, en route to Earth, to prepare for the capsule’s descent maneuver. But the most critical phase of the operation will take place on Sunday the 24th.
At 12:42 (Spanish peninsular time), and when the spacecraft is 102,000 kilometers from Earth, those responsible for the mission, depending on the state of health of OSIRIS-REx and the conditions at the landing site , they will order the separation of the capsule and it will enter the atmosphere, over the coast of California, at 16:42. A thermal shield will protect it from the intense heat caused by friction with the air and will serve to slow down the speed of fall (which at the highest moments will exceed 44,000 km/h). Later, a parachute will reduce the rate of descent to 18 km/h.
About thirteen minutes after entering the atmosphere, the capsule is expected to touch down in a pre-established area of ??the Utah desert belonging to the North American Department of Defense. There, NASA recovery teams, who have trained in the operation in recent weeks, will wait for her and transport her to a clean room specially prepared for this at a nearby military installation. The capsule will later be sent to the Johnson Space Center in Houston, where it will be guarded until its opening.
For its part, twenty minutes after the capsule separates, the OSIRIS-REx spacecraft will fire its engines again to correct its trajectory and head towards its next target, the asteroid Apophis.
It is estimated that the capsule contains around 250 grams of material, an amount much higher than the 60 grams that were set as the mission’s objective. NASA will distribute approximately a quarter of the samples to various research centers, and will hold the rest for future analysis.
OSIRIS-REx was launched into space in 2016, and two years later it was placed in orbit of Bennu, an asteroid about 500 meters in diameter and belonging to the population of objects that move relatively close to Earth.
From orbit around the asteroid, the mission’s scientists and engineers studied, for months, which would be the best place to perform the descent maneuver to the surface. The idea was to find a place relatively clear of large rocks that could be dangerous for the ship. Finally, NASA decided on a place that was named “Nightingale.”
On October 20, 2020, with an autonomous maneuver, the spacecraft gently descended towards Bennu and touched the surface of the asteroid with the end of a mechanical arm. At that precise moment, the arm fired a stream of nitrogen gas, which is inert, to cause stones and sand to rise, and at the same time the ship ascended again to avoid being damaged. At the end of the mechanical arm there was an open container with the objective of collecting part of the material ejected into space during the maneuver.
Shortly after the operation, NASA not only confirmed the success of the maneuver, but announced that the large number of fragments collected made it difficult for the container to close to protect the samples. Finally, closure was achieved and OSIRIS-REx made its way back to Earth on May 10, 2021.
In a very similar mission carried out by the Japanese space agency in December 2020, 5.4 grams of material from the Ryugu asteroid collected by the Hayabusa-2 mission arrived on Earth.
In April of last year, NASA decided to extend the OSIRIS-REx mission, and for that reason, once it has detached from the capsule with the Bennu samples, the spacecraft will head towards a next target, the asteroid Apophis, where it will arrive in 2029. The mission will be renamed OSIRIS-APEX.
Apophis is an object about 370 meters in diameter and considered potentially dangerous. After its discovery in 2004, the first trajectory calculations generated some concern, since they showed a probability of impact with the Earth of 2.7% for April 13, 2029.
This eventuality has currently been ruled out, although the large rock will pass extraordinarily close to our planet. That day, it will cross the skies at about 32,000 kilometers high, below the orbit of geostationary satellites, and will become a point of light visible in the night of Europe, Africa and Asia. It will be just after the next passage of Apophis when OSIRIS-APEX enters orbit around the asteroid and begins its study of the object, which it will carry out for 18 months.
During its visit, the orbit of Apophis will be disturbed by the Earth’s gravity, so that another approach of the asteroid that was initially worrying, that of the year 2036, will already take place about 46 million kilometers away. Although astronomers rule out any possibility of an impact on our planet at least in the next hundred years, Apophis will continue to be highlighted on the list of potentially dangerous objects that will have to be constantly monitored.
The study of asteroids is very important for science. First of all, they are considered relics formed in the first moments of life of our solar system, and their analysis can provide relevant information to better understand the processes that took place in that initial phase.
Secondly, the analysis of the composition of nearby asteroids is essential to be able to develop protection mechanisms if necessary, for example to be able to divert their trajectory if a possible future impact is calculated.
In this sense, in September 2022, NASA successfully carried out the first test in history to deflect an asteroid. The DART spacecraft did so by impacting Dimorphos, a 160-meter object that is part of the binary asteroid Didymos.
