Nasa’s OsirisRex capsule touched down three minutes ahead of schedule at 15:52pm BST on Sunday afternoon after a seven-year four billion-mile journey to collect samples from a killer asteroid Bennu.
But when Nasa blasted off in 2016 to drill for space dust on a giant rock, experts could never have expected to need the help of a rock giant.
The mission ran into trouble after reaching Bennu in 2020 and finding the surface was strewn with boulders, leaving mission controllers scratching their heads about where to land.
Step forward Sir Brian May, the Queen guitarist, who had used Nasa’s public images of Bennu to create 3D stereoscopic pictures, giving unprecedented new detail of the tumbling space rock.
The team used his images to select the Nightingale crater, launched a space drill and collected samples which on Sunday returned to Earth at the end of a seven year mission.
Nasa wanted to sample Bennu because there is a slim chance it will hit Earth in September 2182, unleashing the force of 22 atom bombs.
Knowing its make-up will help the space agency launch a deflection mission if needed.
The asteroid is also a pristine time-capsule that has been floating in space since the formation of the solar system and could give crucial insight into how Earth formed and how life got going.
Sir Brian, who has published several books of stereoscopic images, said: “While a simple photo can tell you a lot, it doesn’t let you know if a crater is flat enough to be able to land a spacecraft on. A stereoscopic picture gives you this extra insight.
“As if by magic you get that in-depth experience and we were able to pick the actual spot where they were going to attempt the landing.
“It worked, they got their sample without mishap and in retrospect I think we realised it was much more risky than we thought at the time because of the nature of the surface of Bennu, because of it not being a solid body, it’s much more like a ball pit.”
Bennu is about the size of the Empire State Building and swings close to the Earth every six years, but it will have its closest shave 159 years from now.
Although the odds of it hitting Earth are 1 in 2,700, Nasa estimates that it could cause a six-mile wide crater and wreak devastation over a 600-mile radius.
After viewing Sir Brian’s images, Nasa was forced to redesign the spacecraft’s guidance system so that it could hit its new target.
Prof Dante Lauretta, the leader of the Osiris-Rex mission said: “Bennu turned out to have a rough and rugged surface strewn with boulders, which was really different from what we had anticipated.
“This meant that we needed to get a better idea of what was on the surface.
“With Brian’s stereo images, we very quickly came to realise that the finely grained material which our sampling mechanism could collect was concentrated in very small craters of about 10 to 20 metres in diameter.”
The spacecraft launched on Sept 8 2016 and arrived at Bennu in December 2018, and, after mapping the asteroid for almost two years, collected a sample from the surface on Oct 20 2020 before returning to Earth.
A capsule containing the 8.8 ounces, or 250 grams, of material from Bennu was jettisoned from the Osiris-Rex spacecraft on Sunday, entering the Earth’s atmosphere at nearly 28,000 mph, and reaching temperatures twice as hot as lava.
Parachutes were deployed to slow the capsule down to 11mph so it could land safely in the Utah Desert south-west of Salt Lake City at 15:52 BST, around three minutes ahead of schedule.
The capsule will be opened in a specially built clean room in the Johnson Space Center, Houston, and the dust stored under a nitrogen atmosphere, using technology developed for the curation of the Apollo lunar rocks.
Although the Japanese Hayabusa spacecraft has brought samples back from an asteroid before, it is Nasa’s first asteroid sample and the amount collected is 50 times larger than previous missions.
Samples will be sent to 35 labs across the world including the Natural History Museum and Manchester University, although 75 per cent will be held back for future generations to study with new scientific techniques.
Bennu is thought to be rich in organic molecules, which are made of chains of carbon bonded with atoms of oxygen, hydrogen, and other elements in a chemical recipe that makes all known living things. Scientists expect it to also contain water and minerals and possibly precious metals.
Prof Sara Russell, senior research lead, Natural History Museum, said: “The holy grail for us would be to find out Bennu is different to any of the meteorites in our collections here, because then it might mean that we need to rethink what the building blocks of our habitable planet are and what was available to seed life on early Earth.
“The broader Osiris-Rex science team are going to do a deep dive on the organic molecules present in the sample, to look at whether this provides clues about how life may have begun.
“Looking at the impact hazard is a key aim of the space mission. By studying its physical properties, such as its density, porosity, strength, and interaction with the sun’s radiation, we can learn how to potentially deflect hazardous asteroids in the future.”
Twenty minutes after the capsule drop-off, the Osiris-Rex spacecraft will fire its thrusters to divert past Earth to visit another asteroid Apophis in 2029 under a new mission name Osiris-Apex.
Dr Sarah Crowther, research fellow in the department of Earth and environmental sciences at the University of Manchester, said: “Meteorites get hot coming through Earth’s atmosphere and can sit on Earth for many years before they are found, so the local environment and weather can alter or even erase important information about their composition and history.
“Sample return missions like Osiris-Rex are vitally important because the returned samples are pristine, we know exactly which asteroid they come from and can be certain that they are never exposed to the atmosphere so that important information is retained.”
Asteroid Bennu is rich in carbon, meaning it could contain the chemical building blocks of life.
The 3D images which Nasa used are published in a new book Bennu 3-D: Anatomy of an Asteroid by Sir Brian May and Prof Dante Lauretta.