A space capsule carrying samples from an asteroid 82 million kilometres from Earth landed in the Utah desert of the United States, marking the historic culmination of a seven-year mission and a first for NASA and just the third for humanity.
On Sunday, the OSIRIS-REx mission of the American space agency, which was launched in 2016, released the sealed capsule carrying the sample from the asteroid 101955 Bennu that it had been orbiting. The spacecraft then continued to investigate its next target, the asteroid 99942 Apophis, which it will encounter in 2029.
It is anticipated that examination of the unusual sample would provide details regarding the development of the solar system and life. Between Mars and Earth, Bennu revolves around the Sun. It is classified as a “near-Earth” asteroid and may strike the planet in a few millennia. Analysis of the materials is anticipated to reveal information about the beginnings of life because it is a carbonaceous asteroid that is abundant in organic compounds.
NASA scientists and engineers referred to it as a “amazing treasure trove for generations” at a press conference held after the sample was retrieved on Sunday afternoon. Now, they want to make sure the sample is clean and unharmed by biological agents throughout analysis.
Even though this is just a NASA mission, Japanese experts will also work with us on the study. NASA previously received two samples from two distinct asteroids from the Japanese space agency, JAXA.
Before returning to Earth in 2020, the OSIRIS-REx mission, which left for Bennu in 2016, obtained the sample. Experts in explosives recovered the Bennu sample off the asteroid, which contained at least 60 grammes of material, and took it to a clean room for examination. Although this is the first sample return for NASA, Japan’s Hayabusa 1 and 2 recovered samples from the near-Earth asteroids 25143 Itokawa and 162173 Ryugu in 2010 and 2018, respectively.
Now officially known as OSIRIS-APEX, an abbreviation for Origins, Spectral Interpretation, Resource Identification, Security, APophis EXplorer, the expanded OSIRIS-REx mission was first launched in 2015. Earlier, the “REx” in the name stood for “regolith explorer”.
The asteroid Bennu is 560 metres broad. The spacecraft reached its orbit in December 2018 and spent the next two years circling it, studying its surface and choosing a landing site.
The spacecraft lowered itself to the asteroid’s surface in October 2020 in order to collect a sample, and it then extended out a robotic arm known as the Touch And Go Sample Acquisition Mechanism (TAGSAM).
High pressure nitrogen gas was released below the surface when the arm made contact with it, blowing regolith or surface particles into the arm’s sample collection. The arm was withdrawn after five seconds, and it was then shown that a sample had been gathered in the arm.
In 2020, NASA reported that they had been able to gather between 400 gm and 1 kilogramme of material off the asteroid, which matched the mission’s stated goal of collecting at least 60 gm of material from the object.
After sealing the sample within the return capsule, the spacecraft started its return to Earth preparations. The spacecraft finished its final orbit of Bennu in April 2021, and in May it started its trip back towards Earth.
The NASA New Frontiers project, which also includes the Juno mission around Jupiter and the New Horizons mission that sailed by Pluto, contains the $800 million mission. In April 2029, OSIRIS-REx will meet the asteroid Apophis and begin an 18-month orbit around it. It won’t be required to return a sample, but it will nonetheless engage in a similar surface-disturbing action to examine the substance underneath.
Bennu, Itokawa, Ryugu, and Apophis are examples of asteroids that are categorised as near-Earth objects (NEOs) because of how closely they circle the Sun and may be tracked for future impacts.
This distance is estimated to be 1.3 astronomical units (au) from the solar, where one astronomical unit is equal to 150 million km between the earth and the sun. Mostly asteroids, but occasionally comets as well, are considered near-Earth objects. A potentially hazardous object (PHO) is one that crosses Earth’s orbit and has a diameter more than 140 m. Over 30,000 near-Earth asteroids are being actively observed. Because NEOs are relatively smaller rocks than planets, ranging in size from a few metres to several kilometres, they usually have minimal surface gravity.
Five of these near-Earth asteroids have been closely examined by spacecraft: China’s Chang’e 2 lunar mission passed by 4179 Toutatis in 2012, and NASA’s NEAR Shoemaker orbited and landed on 433 Eros in 2001–2002. The US brought back a sample from Bennu, while Japan also visited Itokawa and Ryugu.
Apophis is a silicate and stony asteroid that is OSIRIS-APEX’s new destination. Its structure and composition are very different from Bennu. It is a PHO with a 370 m diameter. In addition to analysing the rock composition for hints about the solar system’s and life’s origins, scientists have also carried out a planetary defence experiment to shield the Earth from an incoming asteroid.
Theoretically, a little impact with a large enough asteroids on a collision path with Earth may cause the asteroids to deviate from their orbit and migrate away. This was shown in the NASA DART mission last year, in which a spacecraft was despatched to the (harmless) asteroid Didymos and successfully changed its orbit by impacting its moon Dimorphos.