OSIRIS-Rex Plays TAG with Asteroid Bennu

On October 29, 2020, NASA published an image of OSIRIS-REx stowing its sample of Asteroid Bennu on its way back to Earth. The mission that OSIRIS-REx carried out was taking a piece of Asteroid Bennu and bringing it back to Earth. The scientist on Earth will analyze the samples and see the makeup of the asteroid and see how the solar system formed. The mission will also help determine the source of organic compounds on Earth. If the mission is successful, it will be the first time the United States returns samples from an asteroid. The mission was a collaboration between NASA, the University of Arizona, and Lockheed Martin. Scientists from the United States, Canada, France, Germany, the UK, and Italy all worked together. NASA also got a lot of help from Japan, which was the first nation to bring a sample back from an asteroid in 2010.

Render of OSIRIS-Rex on Asteroid Bennu

OSIRIS-REx is an acronym that stands for Origins, Spectral Interpretation, Resource Identification, Security, and Regolith Explorer. There are 5 main objectives of the mission:

1. Return and analyze a sample of pristine carbonaceous asteroid regolith in an amount sufficient to study the nature, history, and distribution of its constituent minerals and organic compounds.

2. Map the global properties, chemistry, and mineralogy of a primitive carbonaceous asteroid to characterize its geologic and dynamic history and provide context for the returned samples.

3. Document the texture, morphology, geochemistry, and spectral properties of the regolith at the sampling site in situ at scales down to millimeters.

4. Measure the Yarkovsky effect (a thermal force on the object) on a potentially hazardous asteroid and constrain the asteroid properties contributing to this effect.

5. Characterize a primitive carbonaceous asteroid's integrated global properties to allow for direct comparison with ground-based telescopic data of the entire asteroid population.

Many mechanisms are on the OSIRIS-REx satellite. Some of the instruments include the OCAMS, the OVRIS, the OTES, the REXIS, the OLA, and the TAGASM. The OCAMS stands for OSIRIS-REx Camera Suite and consists of the PolyCam, the MapCam, and the SamCam, which all help map the asteroid’s surface and show pictures of the samples and Bennu to NASA.

OSIRIS-Rex Insturment Deck

The OVRIS stands for the OSIRIS-REx Visible and IR Spectrometer and is a spectrometer that will help analyze the asteroid's surface and provide data to NASA where to pick up samples from. The OTES stands for the OSIRIS-REx Thermal Emission Spectrometer. This device offers thermal emission spectral maps and thermal infrared channels and wavelengths from Bennu to map organic and mineral substances. The REXIS stands for Regolith X-ray Imaging Spectrometer, which will provide an X-ray spectroscopy map of Bennu to map element abundances and was created in collaboration with MIT and Harvard University. The OLA stands for OSIRIS-REx Laser Altimeter. It is a lidar scanner that would provide a topographical map of Bennu. The final mechanism is TAGASM. The TAGASM stands for Touch-and-Go Sample Acquisition Mechanism. It is the actual mechanism that would collect the sample from Bennua and will be able to hold 60 grams of surface material from Bennu.

Bennu is an exciting asteroid. Bennu’s real name is 101955 Bennu. The asteroid was first discovered on September 11, 1999. It is listed as a potentially hazardous object on the Sentry Risk Table. This is because there is a 1-in-2700 chance that Bennu would collide with the Earth. Now don’t worry. That's a minimal chance. Bennu has a mean diameter of 490 meters and is named after an ancient Egyptian mythical bird associated with the Sun.

Asteroid Bennu

OSIRIS-REx launched on September 8, 2016, from KSC LC 41 on a United Launch Alliance Atlas V. The launch was “exactly perfect” with nothing going wrong. To meet the asteroid eventually, OSIRIS-REx had to make a few maneuvers. Its first deep-space maneuver was on December 28, 2016. This maneuver helps change its velocity, making it easier to change orbit. Additional thrusters were fired on January 18, 2017. Eventually, with the help of a gravity assist, it was able to cruise to an encounter with Bennu in December 2018. On December 3, 2018, OSIRIS-REx matched the speed of Bennu. On December 31, 2018, OSIRIS-REx started its orbit around Bennu. 

OSIRIS-REx started its sampling procedure by selecting 4 sampling sites. These sites were names Sampling Site Nightingale, Sampling Site Kingfisher, Sampling Site Osprey, and Sampling Site Sandpiper. On December 12, 2019, it was announced that the sample would be taken from Sampling Site Nightingale.

Images of All The Sample Sights

Initially, the procedure would take place in August 2020, but it was rescheduled for October 2020. The system, named Touch-and-Go (TAG), took place on October 20, 2020. In the TAG procedure, the TAGASM head would briefly touch the asteroid and store the samples in the arm.

TAGASM Head Collecting Samples

OSIRIS-REx briefly touched Bennu for a second and was able to pick up the pieces. Through TAG, OSIRIS-Rex was able to secure 60 grams of surface material. The TAGASM head was stored safely on OSIRIS-REx on October 28, 2020. The sample is scheduled to return to Earth on September 24, 2023.

This mission, if successful, will be a significant milestone for NASA. The sample expected to arrive back to the Earth will be shared with the countries that helped collaborate with NASA. With this asteroid, we will learn a lot about our solar system and our planet. The OSIRIS-REx team is now working on the next step, bringing the sample safely back to Earth, with the departure window opening in March 2021.

Rendering of Samples Being Returned Back to Earth in 2023

Sources:

“101955 Bennu.” Wikipedia, Wikimedia Foundation, 3 Dec. 2020, en.wikipedia.org/wiki/101955_Bennu. 

“OSIRIS-REx.” Wikipedia, Wikimedia Foundation, 10 Dec. 2020, en.wikipedia.org/wiki/OSIRIS-REx.