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Test run with a model of the »Osiris-Rex«: Like a salad bowl – but with precious dust


The mission is entering the decisive phase: At an altitude of around 102,000 kilometres, NASA's Osiris-Rex probe is scheduled to release the sample from the asteroid Bennu over the desert of the US state of Utah on Sunday in a week's time. Throwing a capsule out of a probe is a bit like playing darts – but on a basketball court, says Nasa manager Rich Burns.

Hours later, the capsule will enter the Earth's atmosphere, protected by a heat shield, and about 13 minutes later it will touch down on an area of about 58 by 14 kilometers with the help of parachutes.

If all goes well, it would be the first successfully brought sample of an asteroid to Earth in NASA's history – and probably the largest such sample ever taken. "A piece of solar system history," as NASA scientist Nicola Fox says.

She and her colleagues estimate that there are around 250 grams of dust and debris in the capsule. It has a diameter of about 81 centimetres, weighs around 46 kilograms and looks like a salad bowl with a high lid.

In 2005, the Japanese space probe "Hayabusa" landed on an asteroid. In 2010, it brought back to Earth the first soil samples of such a celestial body ever collected. There have been other flights to asteroids, but no other probe has yet returned material to Earth.

Even the removal of the sample by "Osiris-Rex" (the abbreviation stands for: Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) in October 2020 was a complicated and spectacular maneuver lasting several hours: The probe, launched in 2016 from the Cape Canaveral spaceport, had temporarily left its place in Bennu's orbit and approached it to within a few meters. Using a robotic arm of sorts, she touched the surface of the asteroid for about five seconds, ejecting pressurized nitrogen to stir up sample material, which was then sucked up.

Bennu could hit Earth

The jet-black Bennu, named after an ancient Egyptian deity, has a diameter of around 550 meters and could come close to Earth in just over 150 years. Even though the risk of impact is very low, NASA is one of the most dangerous asteroids currently known to Bennu – and therefore wants to study it very closely.

In addition, the scientists hope that the "Osiris-Rex" mission, which will cost around one billion dollars, will provide insights into the formation of the solar system more than 4.5 billion years ago, because asteroids are remnants of it.