NASA's asteroid-chasing spacecraft makes flyby of Earth

OSIRIS-REx to collect samples from asteroid Bennu

NASA's asteroid-chasing spacecraft OSIRIS-REx will make an Earth flyby Friday, Sept. 22, 2017.
NASA's asteroid-chasing spacecraft OSIRIS-REx will make an Earth flyby Friday, Sept. 22, 2017. (NASA)

CAPE CANAVERAL, Fla. – OSIRIS-Rex, the asteroid-chasing spacecraft that launched from the Space Coast last year marked its first milestone Friday during a seven-year journey.

The NASA spacecraft swung by Earth Friday afternoon using Earth’s gravity to help slingshot the probe toward its final destination: asteroid Bennu. OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) is scheduled to fly along side Bennu in 2018, collect surface material from the asteroid and carrying the first sample collected by the U.S. back to Earth for a 2023 arrival.

OSIRIS-REx launched on Sept. 8, 2016, atop a United Launch Alliance Atlas V rocket, and has been orbiting the sun ever since readying for its near-Earth flyby.

On Friday, the spacecraft made its closest approach to Earth, about 11,000 miles above the planet above Antarctica at 12:52 p.m. EDT. The eastern half of Australia had the best viewing opportunity, according to NASA.

“Congratulations @OSIRISREx team on a successful Earth Gravity Assist - trajectory is absolutely perfect - right up the middle!” OSIRIS-REx principal investigator Dante Lauretta said in a tweet Friday afternoon.

The slingshot by Earth allows OSIRIS-REx to save energy by using the planet’s gravity as an extra boost and putting the probe in line with its target, Bennu.

The OSIRIS-REx team encouraged Earthlings to submit their ground-based observations taken during the flyby Friday. Participants can upload their images at asteroidmission.org.

“The opportunity to capture images of the OSIRIS-REx spacecraft as it approaches Earth provides a unique challenge for observers to hone their skills during this historic flyby,” Lauretta said pre-flyby. “As the spacecraft approaches Earth for its own imaging campaign, ground-based observers will also be looking up and taking photos from the opposite perspective.”

On Friday OSIRIS-REx will follow this path to make an Earth flyby.
On Friday OSIRIS-REx will follow this path to make an Earth flyby.

The flyby acts as a dry run for the science instruments on OSIRIS-REx, including it's camera and spectrograph that will eventually map Bennu.

"It will give us a chance to produce data with several different filters and to test the whole pipeline on a real object that will be somewhat predicable, minus cloud cover," said Humberto Campins, a University of Central Florida physics and astronomy professor and a member of OSIRIS-REx's science team.

Campins is one of two UCF faculty selected for the asteroid mission's science team. Associate professor Yan Fernandez, who specializes in comets and asteroids, was also selected.

After the flyby the OSIRIS-REx team will be able to better calibrate the spacecraft's instruments using the images and data taken of the Earth and the moon. Since launch, the team has been running tests on synthetic data of Bennu and using data from the asteroid Eros taken by NASA’s Near Earth Asteroid Rendezvous Shoemaker, the first spacecraft to touch down on an asteroid.

"We are preparing for the encounter with Bennu and have a hint of new scientific data," Campins said. "We're using the new data of asteroid (Eros) to test out approach, so far that's going well."

Bennu was selected for study because it’s thought to be upwards of 4.5 billion years old, essentially a fossil of our solar system. It also has the potential to threaten Earth, but not for another 160 years.

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