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Nasa ‘in final leg’ of mission to halt asteroid armageddon
Samples from an Empire State Building-sized space rock heading for Earth will finally return after a seven-year mission in deep space
On 24 September 2182, there is a chance that an asteroid named Bennu will hit Earth with the force of 22 atom bombs.
The Empire State Building-sized space rock swings close to our planet every six years but will have its closest shave 159 years from now.
Although the odds of a catastrophic strike are 1 in 2,700, Nasa was concerned enough to launch a spacecraft to Bennu seven years ago to collect samples, in case an Armageddon-style deflection mission is required.
Asteroid samples from the OSIRIS-REx mission will finally reach Earth next week, touching down in the Utah desert on Sept 24 - the same date as the future apocalypse Nasa is seeking to avert.
“We are now in the final leg of this seven-year journey, and it feels very much like the last few miles of a marathon, with a confluence of emotions like pride and joy coexisting with a determined focus to complete the race well,” said Rich Burns, project manager for OSIRIS-REx at Nasa’s Goddard Space Flight Center in Greenbelt, Maryland.
Bennu is about a third of a mile wide, so it is not big enough to cause a planet-wide extinction. For comparison, the asteroid which wiped out the dinosaurs was six miles wide.
However, Nasa estimates that it could cause a six-mile wide crater and wreak devastation over a 600-mile radius.
Overall there is a 1-in-1,750 chance that Bennu could collide with Earth between now and 2300.
The space agency is taking the threat from space rocks seriously and last year carried out its first asteroid deflection test, showing it could alter the orbit of the small moonlet Dimorphos.
The samples, which are contained in a fridge-sized capsule, will be fired to Earth from the OSIRIS-REx spacecraft once it reaches a distance of 63,000 miles from the planet.
On board are an estimated 8.8 ounces, or 250 grams, of rocky material collected from the surface of Bennu in 2020. Although the Japanese Hayabusa mission has brought samples back from an asteroid before, it is Nasa’s first asteroid sample and the largest amount ever collected in space.
The capsule will enter Earth’s atmosphere at around 3.42 pm BST on September 24, traveling at nearly 28,000 mph, and reaching temperatures twice as hot as lava.
Parachutes will then deploy to slow the capsule down to 11 mph so it can land safely at the Department of Defense’s Utah Test and Training Range southwest of Salt Lake City.
The recovery team must retrieve the capsule from the ground as quickly as possible to avoid contaminating the sample with Earth’s environment.
Once located, the capsule will be flown to a temporary clean room on the military range, where it will undergo initial processing in preparation for its journey to Nasa’s Johnson Space Center in Houston for study.
As well as helping protect the planet, samples from Bennu - named for the ancient Egyptian phoenix - could also hold secrets about the origin of life on Earth.
The spinning-top-shaped space rock is more than four and a half billion years old and is a leftover relic from the formation of the Solar System which has been perfectly preserved in the vacuum of space.
Scientists have long suspected that the ingredients for life on Earth may have been delivered to our planet by asteroids, and so are keen to find out whether there are life-forming compounds in the samples.
Professor Dante Lauretta, leader of the OSIRIS-REx mission said: “The return of samples from Bennu is the culmination of over a decade of intense effort by thousands of people around the world.
“These samples will be analyzed by hundreds of researchers to unravel the history of our Solar System, the formation of the Earth, and, possibly, the nature of the building blocks of life.”
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.
Nicola Fox, associate administrator of Nasa’s Science Mission Directorate in Washington: “Pristine material from asteroid Bennu will help shed light on the formation of our Solar System 4.5 billion years ago and perhaps even on how life on Earth began.”
Twenty minutes after the capsule drop-off, the OSIRIS-REx spacecraft will fire its thrusters to divert past Earth to visit another asteroid Apophis under a new mission name OSIRIS-APEX.
Apophis was also predicted to get dangerously close to Earth in 2068, but experts have since revised their calculators and no longer see it as a risk.