Spaceflight Insider

NASA’s OSIRIS-REx spacecraft in good health after testing its thrusters


An artist’s rendering of the OSIRIS-REx Spacecraft at Bennu. Image Credit: James Vaughan / SpaceFlight Insider

NASA’s OSIRIS-REx spacecraft continues its, so far, flawless journey to asteroid Bennu after successfully completing its first Trajectory Correction Maneuver (TCM-1) on Oct. 7. According to the mission’s Deputy Principal Investigator, the probe is currently in good health and all of its instruments are working properly.

“The spacecraft, which is now in Outbound Cruise phase, is in good health,” Heather Enos, OSIRIS-REx’s Deputy Principal Investigator at the University of Arizona, told “All five science instruments were powered on and passed their initial checks the week of Sept. 19. We received data back from each of them as expected and captured our first images of star fields from the OSIRIS-REx Camera Suite (OCAMS).”

OSIRIS-REx's StowCam image of the spacecraft's Sample Return Capsule.

OSIRIS-REx’s StowCam image of the spacecraft’s Sample Return Capsule. Photo Credit: NASA/GSFC/University of Arizona

Launched on Sept. 8, 2016, atop an Atlas V rocket, the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) spacecraft is on track for its rendezvous with asteroid Bennu in August 2018. Besides thoroughly studying Bennu, the mission has an ambitious goal of returning a pristine sample of this small body to Earth in 2023 for detailed analysis.

In the second half of September, the mission team was busy checking the spacecraft’s instruments. The set of tests started on Sept. 19 with OCAMS when it was powered on, allowing the controllers to conduct a test sequence with no issues. Next, the OSIRIS-REx Laser Altimeter (OLA) fired its laser and all telemetry received from this instrument was obtained as expected.

On Sept. 20, data from the OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) and the OSIRIS-REx Thermal Emissions Spectrometer (OTES) acquired during the checkout showed those instruments were healthy. Next, the Regolith X-ray Imaging Spectrometer (REXIS) passed its functional test with no problems. Finally, on Sept. 22, the Touch and Go Camera System (TAGCAMS) navigational camera was powered on and operated as expected.

“On Sept. 22, OSIRIS-REx also switched on the Touch and Go Camera System (TAGCAMS) to demonstrate proper operation in space,” Enos said. “TAGCAMS is composed of two navigation cameras, called NavCams, and one color camera called StowCam. The StowCam portion of the system, which will document proper stowage of the asteroid sample once it is collected in 2020, captured a great image of the spacecraft’s Sample Return Capsule.”

With all the instruments working as expected, OSIRIS-REx was ready for its crucial first Trajectory Correction Maneuver (TCM-1) scheduled for Oct. 7. The 12-second long maneuver slightly adjusted the spacecraft’s trajectory toward Bennu. The velocity of the spacecraft increased by about 1.1 mph (50 centimeters per second). It used about 18 ounces (0.5 kilograms) of fuel.

“This maneuver was originally included in the flight plan to fine-tune the spacecraft’s trajectory, if needed, after launch. But our rocket – a ULA Atlas V 411 – performed so accurately that we really didn’t need to adjust the spacecraft’s trajectory,” Enos said. “Instead, the team used TCM-1 to test out the TCM thrusters and as practice for a much larger propulsive maneuver scheduled for December.”

The maneuver in December will be used to fire the spacecraft’s Main Engine thrusters to target the probe for its Earth Gravity Assist, scheduled for Sept. 22, 2017. This fly-by of Earth will provide OSIRIS-REx an additional boost to increase its orbital inclination and sling it into space for a rendezvous with Bennu.

“If things continue the way they have been going since launch, it should be smooth sailing to Bennu,” Enos said.



Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

Reader Comments

This is a fascinating mission. I look forward to future updates

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