Part of the sample from the asteroid Bennu brought back to Earth during the Osiris-Rex mission by NASA (NASA TV / Handout)
The sample from the asteroid Bennu brought back to Earth by NASA contains water and carbon in large quantities, the American space agency announced on Wednesday. A discovery which should allow us to better understand whether asteroids actually brought to Earth the compounds that allowed the birth of life, as some scientists believe.
“Water and carbon molecules are exactly the kind of matter we wanted to find,” NASA boss Bill Nelson said at an event in Houston, Texas.
“These are crucial elements in the formation of our own planet, and they will help us determine the origin of elements that could have led to life,” he added.
The first images of the largest asteroid sample ever brought to Earth have been projected: dust and blackened pieces.
The Osiris-Rex mission took this sample in 2020 on Bennu, an asteroid 500 meters in diameter then located more than 300 million kilometers from Earth. The capsule containing the precious cargo successfully returned to Earth just over two weeks ago, landing in the American desert.
Since then, the meticulous process of opening the capsule has taken place in a white room at NASA’s Johnson Space Center in Houston.
According to initial analyses, this is the richest space sample in carbon ever reported on Earth.
“We chose the right asteroid!”, rejoiced Daniel Glavin, scientist at NASA, speaking of “a dream for astrobiologists”.
NASA’s Osiris-Rex mission capsule containing an asteroid sample after landing in the desert near Dugway, September 24, 2023 in Utah (NASA / Keegan BARBER)
“Carbon is essential for life on Earth, we are all made of carbon,” he explained. By hitting the Earth, asteroids like Bennu could have “seed” our planet.
Water is present on Bennu trapped in what we call hydrated minerals.
“We think that’s how water got to Earth,” said Dante Lauretta, the mission’s principal scientist. “The reason why Earth is a habitable world, why we have oceans, lakes, rivers, is because these hydrated minerals…landed on Earth between 4 and 4.5 billion years ago years.”
– “Bonus” material –
The laboratory where samples from the asteroid Bennu collected by the Osiris-Rex probe will be analyzed, on July 24, 2023 in Houston, Texas (AFP / Mark Felix)
Before the capsule landed, the US space agency estimated it had succeeded in picking up around 250 grams of material from Bennu — far more than two previous Japanese missions to other asteroids.
NASA, for whom such a maneuver was a first, will still have to confirm this estimate.
Perhaps within “two weeks”, when NASA teams have managed to apprehend the entire sample, Dante Lauretta told AFP.
Because the operation to open the capsule had some surprises in store.
Due to the abundance of material found outside the collection mechanism itself, the main sample has not yet been opened.
“We’re taking our time to methodically process and properly care for each piece of Bennu,” said Eileen Stansbery, chief scientist at the Johnson Space Center.
The happy surprise of this “bonus” material can be explained by an incident that occurred when the sample was taken: just after the operation, NASA realized that the valve in the collection compartment was not able to to reclose.
The cargo had managed to be secured by being transferred as planned into the capsule, but because of this leak, scientists expected to find residue outside the compartment.
Image taken by NASA’s Osiris-Rex probe on December 2, 2018, showing the asteroid Bennu (NASA/Goddard/University of Arizona / HO)
The material already recovered was entrusted to a rapid analysis team, in order to obtain a first idea of the composition of Bennu, revealed on Wednesday.
The sample was screened using a scanning electron microscope, X-ray diffraction, and infrared measurements.
– Future generations –
Over the next six months, a NASA team will establish “a catalog of samples”, explained Francis McCubbin, deputy head of this team.
Scientists from around the world will be able to “request material to study Bennu in their own laboratory,” he stressed.
The majority of the sample will be preserved to be studied by future generations, with new, more efficient instruments and to answer new scientific questions. This is what was done for the lunar rocks brought back during the Apollo program.
Bennu’s analysis could also prove very directly useful in the future. There is a small chance (1 chance in 2,700) that the asteroid will hit Earth in 2182, a collision that would be catastrophic.
Knowing its exact composition could thus help to better understand its trajectory, and perhaps even, if necessary one day, to calculate the impact necessary to deviate it.