OSIRIS-REx: Back to the birth of Earth
Rock guitarist Brian May plays surprising role in landing capsule on comet, retrieving evidence
OSIRIS-REx. It sounds like a monster from 70-million years ago that would have had Tyrannosaurus Rex quivering in terror.
Osiris was the ancient Egyptian god of the dead, so who or what was OSIRIS-Rex?
OSIRIS-REx was a seven-year, $1.2bn (R22.5bn) NASA mission to collect some of the original material, from which our solar system, including Earth, formed. The mission’s name is an acronym twisted to fit the name of the Egyptian god with the Latin word for king, Rex. The acronym comes from “Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer OSIRIS-REx. The mission was spectacularly successful.
Our Sun and solar system formed from a cloud of gas and dust in the Milky Way Galaxy 4.5-billion years ago. This cloud was 98% hydrogen and helium with 2% heavier elements that make planets like Earth and make you and me.
As the cloud collapsed under gravity the Sun spun faster and faster, finally spinning off a flat disk of material that became the solar system.
At first small grains formed, before coalescing into rocks which crashed into each other, building asteroids, then planets and moons. Our own Earth formed this way, but we cannot tell what the original rocks were like, since weather, erosion, volcanoes, and continental drift have changed the Earth dramatically over its lifetime.
What scientists want to study is what OSIRIS-REx was sent to get, a piece of the original material that has been orbiting in cold space from the very beginning untouched and unchanged.
OSIRIS-REx has brought home 250g of a small asteroid. Bennu is 500m in diameter and covered in a jumble of rocks, soil, and dust known as regolith.
It is one of many near Earth objects close enough to reach with a space mission. Also, close enough that there is a one in 3,000 chance it will collide with Earth in 2182. If it does, it will explode with the power of a large nuclear bomb, so we want to understand it, in case plans need to be made to deflect it.
OSIRIS-REx was launched on September 8 2016, arriving two years later at Bennu on December 3 2018.
It then orbited Bennu for another two years, studying the asteroid and trying to find a safe place to land to collect material.
That turned out to be a problem. We thought Bennu would have a smooth, dusty surface where we could land anywhere. Instead, it is a big pile of rocks.
If the lander were to hit the edge of
a large rock on the way to the surface, it would crash, and there goes the mission (and $1.2 billion!)
When you spend that much on a vehicle, you drive safely.
Because Bennu was expected to be smooth, OSIRIS-REx did not have a stereoscopic camera to map Bennu in 3D. But there is an astronomer who is expert in stereoscopic imaging.
He contacted the principal investigator of OSIRIS-REx, Dante Lauretta, and offered his services to use the single camera to make 3D images.
Their collaboration was successful and a landing site, “Nightingale”, was chosen. This astronomer had started his PhD in 1971, then was distracted by another career before finally finishing his degree in 2007 36 years later!
His name is Brian May, the guitarist in the rock band Queen.
OSIRIS-REx sent a capsule to Nightingale on October 20 2020 and
successfully collected 250g of the original, pristine solar system.
It then headed home, arriving at Earth on September 24 2023, seven years after its launch, on a collision course at 44,000km/h. A capsule was released with the sample to slam into Earth’s atmosphere, and OSIRIS-REx pulled out of its dive and is now headed for asteroid Apophis. Its new name is OSIRIS-APEX.
The capsule was heated to 3,000°C as it decelerated in the atmosphere, then it opened parachutes to land softly in the Utah desert in the US.
When it cooled, it was taken to a clean room, then transferred to NASA HQ in Houston, Texas.
The material from Bennu will now be studied by scientists all over the world. We think it will tell us what the Earth was originally made of, where the water came from, and it may even have organic material, the seeds of life itself, and possibly part of our origin.
We will begin to hear the answers very soon. Stay tuned.
Donald Kurtz is Extraordinary Professor at North-West University in Mahikeng. He has an A-1 rating from the SA National Research Foundation, its highest rating. He also holds appointments in the UK of Emeritus Professor at the University of Central Lancashire and Visiting Professor of Astrophysics at the University of Lincoln. He was previously Professor of Astronomy at the University of Cape Town, where he worked for 24 years.
Don has contributed to more than 500 professional publications and was awarded the 2022 Service Award of the Royal Astronomical Society for a lifetime of public outreach and for his service on many international committees. He and his wife, who is originally from Grahamstown (Makhanda), now live in Port Alfred.