NASA spacecraft meets with asteroid today

Pablo Tucker
December 4, 2018

OSIRIS-REx, launched in September 2016, will come even closer to Bennu in the coming month and spend nearly one year scrutinising the asteroid before selecting a location that is safe and scientifically valuable to collect the sample.

Let's start with destruction; scientists estimate there is a one-in-2,700 chance of the asteroid slamming catastrophically into Earth 166 years from now. "Beginning with images of Earth and our Moon during the early stages of OSIRIS-REx's flight, then to our first images of Bennu, and up to today, the detector assemblies have been working as designed", said Jed Hancock, SDL's executive director of programs and operations and SDL program manager for OSIRIS-REx.

One of the key goals of the OSIRIS-REx mission is to study the impact of the sun's heat on the orbits of asteroids with the potential to hit Earth and cause substantial damage.

OSIRIS-REx is equipped with five instruments to characterize its target, as well as a robotic arm with a sampling device, a sample return capsule, a high-gain antenna, two 10 foot long solar panels that generate from 1,226 to 3,000 watts (depending on distance from the Sun), and 28 engines (4 main engines, 6 medium thrust engines, 16 attitude control thrusters, and 2 engines for the TAG sampling maneuver). 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. The probe will get within just 1 mile (1.6 km) of Bennu's surface on December 31, she said.

This set of 16 images shows the OSIRIS-REx spacecraft's steady approach toward the asteroid Bennu during the last half of October 2018. Asteroids are remnants of the building blocks that formed the planets and enabled life. Afterward, 75% of the returned sample will remain at NASA's Johnson Space Flight Center so it can be used for more research by scientists from around the world.

All about Bennu: Bennu is a primitive, carbon-rich asteroid believed to be made up of leftovers from the formation of the solar system 4.5 billion years ago. OSIRIS-REx will actually need to spend a good deal of time hanging out in orbit around Bennu before it makes its move, so today is just confirmation of the probe's arrival.

It was discovered in 1999, and scientists have been studying it ever since.

The asteroid Bennu is of interest to Earth for another reason. The asteroid fits a number of criteria that make it intriguing and convenient. OSIRIS-REx will spend another 18 months rigorously scouting for the best place to snag its sample.

The asteroid is also old and well-preserved, full of valuable materials that may even contain clues about how life began.

Bennu probably broke off of a larger asteroid in the asteroid belt between Mars and Jupiter a couple billion years ago. "But while the spacecraft might tell us some things about where we have been and where we are headed, it also can remind us of where we are right now", NASA officials said in a statement.

On the appointed day, OSIRIS-REx will spiral down and tap Bennu with its Touch-And-Go-Sample Acquisition Mechanism (TAGSAM), sucking up at least 2 ounces (60 grams) of material. The NASA team is aiming to determine whether the potentially hazardous asteroid is, in fact, on course to impact the Earth and how we might be able to deflect or destroy it if it is.

Scientists hope to learn more about the source of water in the solar system and the origins of organic molecules from which life first arose. "When we understand Bennu, we will understand something fundamental about our solar system".

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