NASA probe Osiris-Rex becomes ancient asteroid's first visitor

That solar energy is believed to be nudging the asteroid ever closer toward Earth's path each time the asteroid makes its closest approach to our planet every six years.

NASA's first-ever mission created to visit an asteroid and return a sample of its dust back to Earth arrived Monday at its destination, Bennu, two years after launching from Cape Canaveral, Florida.

It launched in September 2016 and will spend two years up close and personal with Bennu. The sample will be small-only 60 grams, or 2.1 oz. -but that's enough material to meet the missions goals.

Ryugu's specks should be here by December 2020, but will be far less than Osiris-Rex's promised booty.

After today, OSIRIS-REx will spend almost a year examining Bennu and sending back highly detailed images of its surface.

In August, the craft snapped its first image of asteroid Bennu.

Finally, it will help unlock the secrets of the solar system. It's because of objects like Bennu that these resources were delivered to Earth during its formation. So close that it's considered a Potentially Hazardous Object (PHO), an object with an orbit that brings it close to Earth, and that's large enough to do serious damage if it struck. Getting their hands on pristine asteroid material might also yield clues about how to mine them for valuable materials and defend against wayward ones that might threaten Earth. Its proximity to us made it a prime target for OSIRIS-REx. Too small, around 200 meters or less in diameter, and it spins so fast you can't land on it. The asteroid, which has a width of 500 meters (1640 feet), could hit Earth between 2175 to 2196, although there is less than a 1 per cent chance of that happening, based on current data.

To capture samples on the surface, the craft will hover over a specific area and "will be sent down at a very slow and gently" 4 inches (10 cm) per second. Astronomers have studied Bennu intensely from a distance, and they know that it's a carbonaceous, or carbon-rich, asteroid.

This carbon-rich asteroid could be full of organic molecules, metals, platinum and even water - the essential ingredients for life.

There are a host of other reasons that NASA chose Bennu, and you can read about them all here.

Osiris-Rex aims to collect at least 60 grams (two ounces) of dust and gravel, the first such attempt by the USA after a smaller mission to another asteroid by Japan.

OSIRIS-REx will fly over Bennu's north pole on 4 December, at a distance of just 7 kilometers.

The spacecraft will now spend nearly a year surveying the space rock from orbit. It has a nice suite of instruments to do its work.

The mission will spend 2.5 years at the 500m-wide rock, mapping its surface and studying its composition.

Another spectrometer, OVIRS, will also be used to obtain spectral data, but from blue to near-infrared wavelengths, to measure organics and minerals. To that end, the College of Optical Sciences, which helped design some of OSIRIS-REx's cameras in conjunction with the Lunar and Planetary Laboratory and Steward Observatory, recently received a $20 million endowment.

Lots of spacecraft have cameras and spectrometers, and laser altimeters are becoming more common, but the main focus of OSIRIS-REx is sample-return.

This set of 16 images shows the OSIRIS-REx spacecraft's steady approach toward the asteroid Bennu during the last half of October 2018.

The cameras will begin recording the sampling site and its surroundings.

Some of Bennu sample will be held in reserve while the rest is subjected to two years of detailed analysis.

The dust will be captured in the sampler head.

In March 2021 OSIRIS-REx will fire its engines for a 2 year return to Earth and on September 24, 2023 at 9 am Mountain (3 pm UTC) the Sample Return Capsule is scheduled to touch down at the Utah Test and Training Range near Dugway.



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